JP7474909B1 - Rare Earth Oxide Powder - Google Patents
Rare Earth Oxide Powder Download PDFInfo
- Publication number
- JP7474909B1 JP7474909B1 JP2023562626A JP2023562626A JP7474909B1 JP 7474909 B1 JP7474909 B1 JP 7474909B1 JP 2023562626 A JP2023562626 A JP 2023562626A JP 2023562626 A JP2023562626 A JP 2023562626A JP 7474909 B1 JP7474909 B1 JP 7474909B1
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- JP
- Japan
- Prior art keywords
- rare earth
- less
- particle size
- earth oxide
- oxide powder
- Prior art date
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- 239000000843 powder Substances 0.000 title claims abstract description 171
- 229910001404 rare earth metal oxide Inorganic materials 0.000 title claims abstract description 123
- 239000002245 particle Substances 0.000 claims abstract description 157
- 239000011148 porous material Substances 0.000 claims abstract description 75
- 239000011164 primary particle Substances 0.000 claims abstract description 73
- 229910052761 rare earth metal Inorganic materials 0.000 claims abstract description 46
- 238000009826 distribution Methods 0.000 claims abstract description 14
- 238000000691 measurement method Methods 0.000 claims abstract description 11
- 238000001132 ultrasonic dispersion Methods 0.000 claims abstract description 8
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 81
- 239000002002 slurry Substances 0.000 claims description 68
- 238000005259 measurement Methods 0.000 claims description 62
- 238000000034 method Methods 0.000 claims description 60
- 239000011324 bead Substances 0.000 claims description 47
- 238000004519 manufacturing process Methods 0.000 claims description 30
- 230000001186 cumulative effect Effects 0.000 claims description 20
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 claims description 16
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 15
- 229910052799 carbon Inorganic materials 0.000 claims description 15
- 238000002296 dynamic light scattering Methods 0.000 claims description 12
- 239000002904 solvent Substances 0.000 claims description 6
- 238000005070 sampling Methods 0.000 claims description 3
- 239000007788 liquid Substances 0.000 description 105
- 238000006243 chemical reaction Methods 0.000 description 43
- 239000000243 solution Substances 0.000 description 41
- 239000007864 aqueous solution Substances 0.000 description 35
- 238000010304 firing Methods 0.000 description 33
- 230000002776 aggregation Effects 0.000 description 30
- 230000000052 comparative effect Effects 0.000 description 28
- 238000000576 coating method Methods 0.000 description 26
- 239000011248 coating agent Substances 0.000 description 25
- -1 Tb4O7 Inorganic materials 0.000 description 24
- 239000002270 dispersing agent Substances 0.000 description 23
- 239000000203 mixture Substances 0.000 description 20
- ATRRKUHOCOJYRX-UHFFFAOYSA-N Ammonium bicarbonate Chemical compound [NH4+].OC([O-])=O ATRRKUHOCOJYRX-UHFFFAOYSA-N 0.000 description 19
- 239000001099 ammonium carbonate Substances 0.000 description 19
- 238000003756 stirring Methods 0.000 description 19
- 229910000013 Ammonium bicarbonate Inorganic materials 0.000 description 17
- 235000012538 ammonium bicarbonate Nutrition 0.000 description 17
- 150000003839 salts Chemical class 0.000 description 17
- 238000000926 separation method Methods 0.000 description 17
- 238000002834 transmittance Methods 0.000 description 17
- NGDQQLAVJWUYSF-UHFFFAOYSA-N 4-methyl-2-phenyl-1,3-thiazole-5-sulfonyl chloride Chemical compound S1C(S(Cl)(=O)=O)=C(C)N=C1C1=CC=CC=C1 NGDQQLAVJWUYSF-UHFFFAOYSA-N 0.000 description 16
- RUDFQVOCFDJEEF-UHFFFAOYSA-N yttrium(III) oxide Inorganic materials [O-2].[O-2].[O-2].[Y+3].[Y+3] RUDFQVOCFDJEEF-UHFFFAOYSA-N 0.000 description 16
- 238000005054 agglomeration Methods 0.000 description 15
- 238000004220 aggregation Methods 0.000 description 15
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 14
- 239000012298 atmosphere Substances 0.000 description 13
- SIWVEOZUMHYXCS-UHFFFAOYSA-N oxo(oxoyttriooxy)yttrium Chemical compound O=[Y]O[Y]=O SIWVEOZUMHYXCS-UHFFFAOYSA-N 0.000 description 13
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 12
- 238000002156 mixing Methods 0.000 description 12
- 239000006185 dispersion Substances 0.000 description 11
- 239000011734 sodium Substances 0.000 description 11
- 238000005406 washing Methods 0.000 description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 11
- 229910052727 yttrium Inorganic materials 0.000 description 11
- 238000011156 evaluation Methods 0.000 description 10
- 229910052692 Dysprosium Inorganic materials 0.000 description 9
- 229910052689 Holmium Inorganic materials 0.000 description 9
- 229910052769 Ytterbium Inorganic materials 0.000 description 9
- 229910052691 Erbium Inorganic materials 0.000 description 8
- 229910052693 Europium Inorganic materials 0.000 description 8
- 229910052688 Gadolinium Inorganic materials 0.000 description 8
- 238000009775 high-speed stirring Methods 0.000 description 8
- 239000011259 mixed solution Substances 0.000 description 8
- 230000008569 process Effects 0.000 description 8
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 7
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 7
- 239000010408 film Substances 0.000 description 7
- 229910052765 Lutetium Inorganic materials 0.000 description 6
- 229910052779 Neodymium Inorganic materials 0.000 description 6
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 6
- 229910052771 Terbium Inorganic materials 0.000 description 6
- 229910052775 Thulium Inorganic materials 0.000 description 6
- 238000001354 calcination Methods 0.000 description 6
- 229910052746 lanthanum Inorganic materials 0.000 description 6
- 239000002244 precipitate Substances 0.000 description 6
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 description 6
- 229920003171 Poly (ethylene oxide) Polymers 0.000 description 5
- 229910052777 Praseodymium Inorganic materials 0.000 description 5
- 239000000654 additive Substances 0.000 description 5
- CETPSERCERDGAM-UHFFFAOYSA-N ceric oxide Chemical compound O=[Ce]=O CETPSERCERDGAM-UHFFFAOYSA-N 0.000 description 5
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- 229910052772 Samarium Inorganic materials 0.000 description 4
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 description 4
- 230000008901 benefit Effects 0.000 description 4
- 230000008859 change Effects 0.000 description 4
- 239000007795 chemical reaction product Substances 0.000 description 4
- 239000011362 coarse particle Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- 239000012535 impurity Substances 0.000 description 4
- 150000002823 nitrates Chemical class 0.000 description 4
- 239000007800 oxidant agent Substances 0.000 description 4
- 238000005245 sintering Methods 0.000 description 4
- 239000007787 solid Substances 0.000 description 4
- 238000009210 therapy by ultrasound Methods 0.000 description 4
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 3
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 3
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- BTANRVKWQNVYAZ-UHFFFAOYSA-N butan-2-ol Chemical compound CCC(C)O BTANRVKWQNVYAZ-UHFFFAOYSA-N 0.000 description 3
- 238000004364 calculation method Methods 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- 238000011109 contamination Methods 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 235000014113 dietary fatty acids Nutrition 0.000 description 3
- 238000009792 diffusion process Methods 0.000 description 3
- 239000002612 dispersion medium Substances 0.000 description 3
- NLQFUUYNQFMIJW-UHFFFAOYSA-N dysprosium(III) oxide Inorganic materials O=[Dy]O[Dy]=O NLQFUUYNQFMIJW-UHFFFAOYSA-N 0.000 description 3
- RSEIMSPAXMNYFJ-UHFFFAOYSA-N europium(III) oxide Inorganic materials O=[Eu]O[Eu]=O RSEIMSPAXMNYFJ-UHFFFAOYSA-N 0.000 description 3
- 239000000194 fatty acid Substances 0.000 description 3
- 229930195729 fatty acid Natural products 0.000 description 3
- 238000001914 filtration Methods 0.000 description 3
- CMIHHWBVHJVIGI-UHFFFAOYSA-N gadolinium(III) oxide Inorganic materials [O-2].[O-2].[O-2].[Gd+3].[Gd+3] CMIHHWBVHJVIGI-UHFFFAOYSA-N 0.000 description 3
- 238000000227 grinding Methods 0.000 description 3
- PLDDOISOJJCEMH-UHFFFAOYSA-N neodymium oxide Inorganic materials [O-2].[O-2].[O-2].[Nd+3].[Nd+3] PLDDOISOJJCEMH-UHFFFAOYSA-N 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 230000002093 peripheral effect Effects 0.000 description 3
- 239000002243 precursor Substances 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- 238000011160 research Methods 0.000 description 3
- 238000010079 rubber tapping Methods 0.000 description 3
- 239000012266 salt solution Substances 0.000 description 3
- 229910052708 sodium Inorganic materials 0.000 description 3
- 229910000029 sodium carbonate Inorganic materials 0.000 description 3
- 235000017550 sodium carbonate Nutrition 0.000 description 3
- 239000012798 spherical particle Substances 0.000 description 3
- 239000000725 suspension Substances 0.000 description 3
- 239000010409 thin film Substances 0.000 description 3
- FIXNOXLJNSSSLJ-UHFFFAOYSA-N ytterbium(III) oxide Inorganic materials O=[Yb]O[Yb]=O FIXNOXLJNSSSLJ-UHFFFAOYSA-N 0.000 description 3
- QVOIJBIQBYRBCF-UHFFFAOYSA-H yttrium(3+);tricarbonate Chemical compound [Y+3].[Y+3].[O-]C([O-])=O.[O-]C([O-])=O.[O-]C([O-])=O QVOIJBIQBYRBCF-UHFFFAOYSA-H 0.000 description 3
- KBPLFHHGFOOTCA-UHFFFAOYSA-N 1-Octanol Chemical compound CCCCCCCCO KBPLFHHGFOOTCA-UHFFFAOYSA-N 0.000 description 2
- QXPQVUQBEBHHQP-UHFFFAOYSA-N 5,6,7,8-tetrahydro-[1]benzothiolo[2,3-d]pyrimidin-4-amine Chemical compound C1CCCC2=C1SC1=C2C(N)=NC=N1 QXPQVUQBEBHHQP-UHFFFAOYSA-N 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-M Bicarbonate Chemical compound OC([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-M 0.000 description 2
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 2
- TWRXJAOTZQYOKJ-UHFFFAOYSA-L Magnesium chloride Chemical compound [Mg+2].[Cl-].[Cl-] TWRXJAOTZQYOKJ-UHFFFAOYSA-L 0.000 description 2
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 2
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 description 2
- 229910002637 Pr6O11 Inorganic materials 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 150000001242 acetic acid derivatives Chemical class 0.000 description 2
- 150000008043 acidic salts Chemical class 0.000 description 2
- 150000005215 alkyl ethers Chemical class 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 235000012501 ammonium carbonate Nutrition 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 2
- 239000003990 capacitor Substances 0.000 description 2
- 239000004202 carbamide Substances 0.000 description 2
- 239000004359 castor oil Substances 0.000 description 2
- 235000019438 castor oil Nutrition 0.000 description 2
- 239000003054 catalyst Substances 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 2
- UNJPQTDTZAKTFK-UHFFFAOYSA-K cerium(iii) hydroxide Chemical compound [OH-].[OH-].[OH-].[Ce+3] UNJPQTDTZAKTFK-UHFFFAOYSA-K 0.000 description 2
- 150000001805 chlorine compounds Chemical class 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 239000003989 dielectric material Substances 0.000 description 2
- 238000010790 dilution Methods 0.000 description 2
- 239000012895 dilution Substances 0.000 description 2
- 229910001882 dioxygen Inorganic materials 0.000 description 2
- 239000000839 emulsion Substances 0.000 description 2
- VQCBHWLJZDBHOS-UHFFFAOYSA-N erbium(III) oxide Inorganic materials O=[Er]O[Er]=O VQCBHWLJZDBHOS-UHFFFAOYSA-N 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 239000000706 filtrate Substances 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- ZEMPKEQAKRGZGQ-XOQCFJPHSA-N glycerol triricinoleate Natural products CCCCCC[C@@H](O)CC=CCCCCCCCC(=O)OC[C@@H](COC(=O)CCCCCCCC=CC[C@@H](O)CCCCCC)OC(=O)CCCCCCCC=CC[C@H](O)CCCCCC ZEMPKEQAKRGZGQ-XOQCFJPHSA-N 0.000 description 2
- JYTUFVYWTIKZGR-UHFFFAOYSA-N holmium oxide Inorganic materials [O][Ho]O[Ho][O] JYTUFVYWTIKZGR-UHFFFAOYSA-N 0.000 description 2
- 230000005764 inhibitory process Effects 0.000 description 2
- MRELNEQAGSRDBK-UHFFFAOYSA-N lanthanum oxide Inorganic materials [O-2].[O-2].[O-2].[La+3].[La+3] MRELNEQAGSRDBK-UHFFFAOYSA-N 0.000 description 2
- 229910003443 lutetium oxide Inorganic materials 0.000 description 2
- 239000002609 medium Substances 0.000 description 2
- 229910017604 nitric acid Inorganic materials 0.000 description 2
- 239000002736 nonionic surfactant Substances 0.000 description 2
- 239000005304 optical glass Substances 0.000 description 2
- KTUFCUMIWABKDW-UHFFFAOYSA-N oxo(oxolanthaniooxy)lanthanum Chemical compound O=[La]O[La]=O KTUFCUMIWABKDW-UHFFFAOYSA-N 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 239000011819 refractory material Substances 0.000 description 2
- FKTOIHSPIPYAPE-UHFFFAOYSA-N samarium(III) oxide Inorganic materials [O-2].[O-2].[O-2].[Sm+3].[Sm+3] FKTOIHSPIPYAPE-UHFFFAOYSA-N 0.000 description 2
- 229910052706 scandium Inorganic materials 0.000 description 2
- HYXGAEYDKFCVMU-UHFFFAOYSA-N scandium(III) oxide Inorganic materials O=[Sc]O[Sc]=O HYXGAEYDKFCVMU-UHFFFAOYSA-N 0.000 description 2
- 238000007790 scraping Methods 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 235000017557 sodium bicarbonate Nutrition 0.000 description 2
- 229910000030 sodium bicarbonate Inorganic materials 0.000 description 2
- GCLGEJMYGQKIIW-UHFFFAOYSA-H sodium hexametaphosphate Chemical compound [Na]OP1(=O)OP(=O)(O[Na])OP(=O)(O[Na])OP(=O)(O[Na])OP(=O)(O[Na])OP(=O)(O[Na])O1 GCLGEJMYGQKIIW-UHFFFAOYSA-H 0.000 description 2
- 235000019982 sodium hexametaphosphate Nutrition 0.000 description 2
- 229910001415 sodium ion Inorganic materials 0.000 description 2
- 229910052717 sulfur Inorganic materials 0.000 description 2
- 239000011593 sulfur Substances 0.000 description 2
- 239000001577 tetrasodium phosphonato phosphate Substances 0.000 description 2
- ZIKATJAYWZUJPY-UHFFFAOYSA-N thulium (III) oxide Inorganic materials [O-2].[O-2].[O-2].[Tm+3].[Tm+3] ZIKATJAYWZUJPY-UHFFFAOYSA-N 0.000 description 2
- 238000000411 transmission spectrum Methods 0.000 description 2
- 238000002604 ultrasonography Methods 0.000 description 2
- 238000001238 wet grinding Methods 0.000 description 2
- KUBYTSCYMRPPAG-UHFFFAOYSA-N ytterbium(3+);trinitrate Chemical compound [Yb+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O KUBYTSCYMRPPAG-UHFFFAOYSA-N 0.000 description 2
- ZORQXIQZAOLNGE-UHFFFAOYSA-N 1,1-difluorocyclohexane Chemical compound FC1(F)CCCCC1 ZORQXIQZAOLNGE-UHFFFAOYSA-N 0.000 description 1
- AZUYLZMQTIKGSC-UHFFFAOYSA-N 1-[6-[4-(5-chloro-6-methyl-1H-indazol-4-yl)-5-methyl-3-(1-methylindazol-5-yl)pyrazol-1-yl]-2-azaspiro[3.3]heptan-2-yl]prop-2-en-1-one Chemical compound ClC=1C(=C2C=NNC2=CC=1C)C=1C(=NN(C=1C)C1CC2(CN(C2)C(C=C)=O)C1)C=1C=C2C=NN(C2=CC=1)C AZUYLZMQTIKGSC-UHFFFAOYSA-N 0.000 description 1
- OBOSXEWFRARQPU-UHFFFAOYSA-N 2-n,2-n-dimethylpyridine-2,5-diamine Chemical compound CN(C)C1=CC=C(N)C=N1 OBOSXEWFRARQPU-UHFFFAOYSA-N 0.000 description 1
- NECRQCBKTGZNMH-UHFFFAOYSA-N 3,5-dimethylhex-1-yn-3-ol Chemical compound CC(C)CC(C)(O)C#C NECRQCBKTGZNMH-UHFFFAOYSA-N 0.000 description 1
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 1
- 238000012935 Averaging Methods 0.000 description 1
- 229920002799 BoPET Polymers 0.000 description 1
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 1
- 206010008428 Chemical poisoning Diseases 0.000 description 1
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 description 1
- 229910002651 NO3 Inorganic materials 0.000 description 1
- 229920001214 Polysorbate 60 Polymers 0.000 description 1
- 229910052581 Si3N4 Inorganic materials 0.000 description 1
- BCKXLBQYZLBQEK-KVVVOXFISA-M Sodium oleate Chemical compound [Na+].CCCCCCCC\C=C/CCCCCCCC([O-])=O BCKXLBQYZLBQEK-KVVVOXFISA-M 0.000 description 1
- NWGKJDSIEKMTRX-AAZCQSIUSA-N Sorbitan monooleate Chemical compound CCCCCCCC\C=C/CCCCCCCC(=O)OC[C@@H](O)[C@H]1OC[C@H](O)[C@H]1O NWGKJDSIEKMTRX-AAZCQSIUSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 238000003917 TEM image Methods 0.000 description 1
- PPWHTZKZQNXVAE-UHFFFAOYSA-N Tetracaine hydrochloride Chemical compound Cl.CCCCNC1=CC=C(C(=O)OCCN(C)C)C=C1 PPWHTZKZQNXVAE-UHFFFAOYSA-N 0.000 description 1
- UDWPONKAYSRBTJ-UHFFFAOYSA-N [He].[N] Chemical compound [He].[N] UDWPONKAYSRBTJ-UHFFFAOYSA-N 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
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- 239000005456 alcohol based solvent Substances 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 125000005907 alkyl ester group Chemical group 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
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- HSFWRNGVRCDJHI-UHFFFAOYSA-N alpha-acetylene Natural products C#C HSFWRNGVRCDJHI-UHFFFAOYSA-N 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 235000011114 ammonium hydroxide Nutrition 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 238000001479 atomic absorption spectroscopy Methods 0.000 description 1
- 238000005311 autocorrelation function Methods 0.000 description 1
- 238000013320 baculovirus expression vector system Methods 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 229920001400 block copolymer Polymers 0.000 description 1
- 239000001110 calcium chloride Substances 0.000 description 1
- 229910001628 calcium chloride Inorganic materials 0.000 description 1
- 239000011538 cleaning material Substances 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000001739 density measurement Methods 0.000 description 1
- 229940105990 diglycerin Drugs 0.000 description 1
- GPLRAVKSCUXZTP-UHFFFAOYSA-N diglycerol Chemical compound OCC(O)COCC(O)CO GPLRAVKSCUXZTP-UHFFFAOYSA-N 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- POULHZVOKOAJMA-UHFFFAOYSA-M dodecanoate Chemical compound CCCCCCCCCCCC([O-])=O POULHZVOKOAJMA-UHFFFAOYSA-M 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000010894 electron beam technology Methods 0.000 description 1
- 239000012776 electronic material Substances 0.000 description 1
- 238000004993 emission spectroscopy Methods 0.000 description 1
- 125000002534 ethynyl group Chemical group [H]C#C* 0.000 description 1
- GAGGCOKRLXYWIV-UHFFFAOYSA-N europium(3+);trinitrate Chemical compound [Eu+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O GAGGCOKRLXYWIV-UHFFFAOYSA-N 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- MWFSXYMZCVAQCC-UHFFFAOYSA-N gadolinium(iii) nitrate Chemical compound [Gd+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O MWFSXYMZCVAQCC-UHFFFAOYSA-N 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 150000004679 hydroxides Chemical class 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 239000002563 ionic surfactant Substances 0.000 description 1
- 230000001678 irradiating effect Effects 0.000 description 1
- 229940070765 laurate Drugs 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 229910001629 magnesium chloride Inorganic materials 0.000 description 1
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000011858 nanopowder Substances 0.000 description 1
- CFYGEIAZMVFFDE-UHFFFAOYSA-N neodymium(3+);trinitrate Chemical compound [Nd+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O CFYGEIAZMVFFDE-UHFFFAOYSA-N 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 238000003921 particle size analysis Methods 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 229920002503 polyoxyethylene-polyoxypropylene Polymers 0.000 description 1
- 229920001451 polypropylene glycol Polymers 0.000 description 1
- 239000001103 potassium chloride Substances 0.000 description 1
- 235000011164 potassium chloride Nutrition 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 150000003138 primary alcohols Chemical class 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000000790 scattering method Methods 0.000 description 1
- 150000003333 secondary alcohols Chemical class 0.000 description 1
- 229910010271 silicon carbide Inorganic materials 0.000 description 1
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 1
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 239000001593 sorbitan monooleate Substances 0.000 description 1
- 235000011069 sorbitan monooleate Nutrition 0.000 description 1
- 229940035049 sorbitan monooleate Drugs 0.000 description 1
- 229910002076 stabilized zirconia Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- UONOETXJSWQNOL-UHFFFAOYSA-N tungsten carbide Chemical compound [W+]#[C-] UONOETXJSWQNOL-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F17/00—Compounds of rare earth metals
- C01F17/20—Compounds containing only rare earth metals as the metal element
- C01F17/206—Compounds containing only rare earth metals as the metal element oxide or hydroxide being the only anion
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F17/00—Compounds of rare earth metals
- C01F17/20—Compounds containing only rare earth metals as the metal element
- C01F17/206—Compounds containing only rare earth metals as the metal element oxide or hydroxide being the only anion
- C01F17/218—Yttrium oxides or hydroxides
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F17/00—Compounds of rare earth metals
- C01F17/20—Compounds containing only rare earth metals as the metal element
- C01F17/206—Compounds containing only rare earth metals as the metal element oxide or hydroxide being the only anion
- C01F17/224—Oxides or hydroxides of lanthanides
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
- C23C4/04—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the coating material
- C23C4/10—Oxides, borides, carbides, nitrides or silicides; Mixtures thereof
- C23C4/11—Oxides
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Inorganic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Plasma & Fusion (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
Abstract
Ce以外の少なくとも1種の希土類元素の酸化物の粉末であって、(a)又は(b)を満たす粉末。(a)一次粒子径が10~60nmで、(I)又は(II)を満たす。(I)超音波分散処理して測定した、レーザー回折・散乱式粒度分布測定法によるD100が1~10μm。(II)希土類酸化物の真密度をρ(g/cm3)としたとき、初期嵩密度ADから算出される空隙率PAD(%)と、タップ嵩密度TDから算出される空隙率PTD(%)の差(PAD-PTD)が2.0~5.0%。PAD=(1-AD/ρ) ×100 (%)PTD=(1-TD/ρ) ×100 (%)(b)一次粒子径が10nm以上100nm未満で、(III)及び(IV)を満たす。(III)細孔直径0.005~100μmの細孔容積(cm3/g)に真密度(g/cm3)を掛けてなる数値が3~14。(IV)細孔直径5~50nmの細孔容積(cm3/g)に真密度(g/cm3)を掛けてなる数値が0~2.0。A powder of an oxide of at least one rare earth element other than Ce, which satisfies (a) or (b). (a) The primary particle size is 10 to 60 nm, and satisfies (I) or (II). (I) D100 is 1 to 10 μm, as measured by a laser diffraction/scattering particle size distribution measurement method after ultrasonic dispersion treatment. (II) When the true density of the rare earth oxide is ρ (g/cm3), the difference (PAD-PTD) between the porosity PAD (%) calculated from the initial bulk density AD and the porosity PTD (%) calculated from the tapped bulk density TD is 2.0 to 5.0%. PAD = (1-AD/ρ) x 100 (%) PTD = (1-TD/ρ) x 100 (%) (b) The primary particle size is 10 nm or more and less than 100 nm, and satisfies (III) and (IV). (III) The value obtained by multiplying the volume (cm3/g) of pores having a diameter of 0.005 to 100 μm by the true density (g/cm3) is 3 to 14. (IV) The value obtained by multiplying the volume (cm3/g) of pores having a diameter of 5 to 50 nm by the true density (g/cm3) is 0 to 2.0.
Description
本発明は、希土類酸化物粉末に関する。 The present invention relates to rare earth oxide powder.
希土類酸化物はコンデンサー用誘電体あるいは内部電極、蛍光体、光学ガラス用屈折率調整剤、酸素センサー、セラミックスの焼結助剤、触媒、耐火物等で用いられている。その使用形態は様々であり、コーティング(塗膜)、微量添加、成型体(焼結体を含む)等がある。 Rare earth oxides are used in dielectrics or internal electrodes for capacitors, phosphors, refractive index adjusters for optical glass, oxygen sensors, sintering aids for ceramics, catalysts, refractories, etc. They are used in a variety of forms, including coatings (paint films), trace additives, and molded bodies (including sintered bodies).
希土類酸化物粉末を含むスラリーを塗膜する場合であって、塗膜後に焼成工程がある場合、希土類酸化物粉末の比表面積を高くしたり、一次粒子を小さくしたりすることで、熱拡散性を高めることができる。また希土類酸化物を添加材として使って、焼成するような場合、一次粒子が小さいと熱拡散し易くなることがある。これらの観点から、種々の希土類酸化物の微粉末が知られている。特許文献1においては、一次粒子が平均80Åの超微粒子イットリウム酸化物が得られたと記載されている(特許文献1の実施例1)。特許文献2では、「走査型電子顕微鏡(SEM)で観察したところ、(中略)粒径がおよそ100nmの凝集のない粒径の揃った球状の粒子群」の酸化イットリウム微粉末が得られたと記載されている(特許文献2の実施例1)。非特許文献1にも、TEMの電子ビームへの長時間曝露の結果として結晶化したDy2O3微粉末のTEM画像が示されている(非特許文献1のFig.1a b) In the case of coating a slurry containing rare earth oxide powder and a firing process is performed after coating, the thermal diffusivity can be improved by increasing the specific surface area of the rare earth oxide powder or reducing the primary particle size. In addition, when using rare earth oxide as an additive and firing, small primary particles may facilitate thermal diffusion. From these viewpoints, various rare earth oxide fine powders are known. Patent Document 1 describes that ultrafine yttrium oxide particles with an average primary particle size of 80 Å were obtained (Example 1 of Patent Document 1). Patent Document 2 describes that yttrium oxide fine powder was obtained in the form of "scanning electron microscope (SEM) observation (omitted) a group of spherical particles with a uniform particle size of about 100 nm without aggregation" (Example 1 of Patent Document 2). Non-Patent Document 1 also shows TEM images of Dy 2 O 3 fine powder crystallized as a result of long-term exposure to the electron beam of the TEM (Fig. 1a b of Non-Patent Document 1).
一方、一次粒子径が小さな、例えば数十nmレベルの粉末の場合、容易に凝集体を形成し、その凝集粒子は、平均粒径が小さな細かいナノ粉末の場合、固い凝集体となる(例えば特許第6119528号公報の段落〔0014〕参照)。そのため、一次粒子が小さな粒子を塗膜するためには、メディア等を使用して高いエネルギーで解砕する必要がある。On the other hand, powders with small primary particle sizes, such as those on the order of several tens of nanometers, easily form agglomerates, and the agglomerated particles become hard agglomerates in the case of fine nanopowder with a small average particle size (see, for example, paragraph [0014] of Japanese Patent No. 6119528). Therefore, in order to coat particles with small primary particles, it is necessary to disintegrate them with high energy using media, etc.
特許文献3には酸化イットリウム粉末を、分散剤を用いてスラリー中に分散させて測定した中央粒径D50が5.3nmであったことが記載されている(特許文献3の実施例1)。Patent document 3 describes that yttrium oxide powder was dispersed in a slurry using a dispersant and the median particle size D50 was measured to be 5.3 nm (Example 1 of Patent Document 3).
微粒の希土類酸化物粉末のスラリーは、適切な分散剤を使用して分散させると高分散化できる(例えば特開2007-126349号公報の段落〔0020〕〔0029〕等を参照)。しかし、配合成分によっては分散剤が作用しない場合もありうるし、また、用途によっては分散剤が不純物となることもある。A slurry of fine rare earth oxide powder can be highly dispersed by using an appropriate dispersant (see, for example, paragraphs [0020] and [0029] of JP 2007-126349 A). However, depending on the ingredients, the dispersant may not work, and depending on the application, the dispersant may become an impurity.
出願人は、特許文献1~2、非特許文献1に記載の方法で製造した希土類酸化物粉末は、走査型電子顕微鏡(SEM)で観察した場合には、一見凝集していないように見えるが、巨視的な測定方法(レーザー散乱法)で凝集径を測定すると大きな粗大粒子が測定されることを知見した。凝集径が大きいと、コーティング液の場合は薄膜の塗工が難しくなる。また凝集径を小さくしようと解砕しても、一次粒子が小さいことに起因して凝集力が強くなるため、強度の分散が必要となり粉砕メディアに由来した汚染が増えるほか、湿式解砕した後に乾燥させた場合には、乾燥時に凝集して粒径が大きくなる。特に、CeO2以外の希土類酸化物の微粉末は凝集抑制が難しかった。 The applicant has found that the rare earth oxide powder produced by the method described in Patent Documents 1-2 and Non-Patent Document 1 does not appear to be aggregated when observed with a scanning electron microscope (SEM), but when the aggregate diameter is measured by a macroscopic measurement method (laser scattering method), large coarse particles are measured. If the aggregate diameter is large, it becomes difficult to apply a thin film in the case of a coating liquid. Even if the aggregate diameter is reduced by crushing, the aggregation force becomes strong due to the small size of the primary particles, so that strong dispersion is required, and contamination originating from the grinding media increases. In addition, when the powder is dried after wet crushing, the powder aggregates during drying and the particle size becomes large. In particular, it is difficult to suppress aggregation of fine powders of rare earth oxides other than CeO2 .
従って第1発明の課題は、強度の解砕処理がなくても容易に分散でき、薄膜の塗膜の形成が可能な希土類酸化物微粉末を提供することにある。 Therefore, the object of the first invention is to provide a rare earth oxide fine powder that can be easily dispersed without intensive crushing treatment and that can form a thin coating film.
本発明者は鋭意検討したところ、特定の一次粒子径(SSA換算径)を有し、且つ所定の超音波処理を供した場合の凝集径を特定の範囲とすることで、或いは、特定の一次粒子径(SSA換算径)を有し、初期嵩密度ADとタップ嵩密度TDとから算出される空隙率差を所定範囲とすることで、驚くべきことに、上記課題を解決できることを見出した。After extensive research, the inventors have surprisingly found that the above problems can be solved by having a specific primary particle diameter (SSA equivalent diameter) and setting the agglomeration diameter within a specific range when subjected to a specified ultrasonic treatment, or by having a specific primary particle diameter (SSA equivalent diameter) and setting the porosity difference calculated from the initial bulk density AD and the tapped bulk density TD within a specified range.
第1発明は、前記知見に基づくものであり、以下の〔a1〕~〔a9〕を提供するものである。
〔a1〕Ce以外の少なくとも1種の希土類元素の酸化物の粉末であって、
一次粒子径10nm以上60nm以下であり、以下の(I)又は(II)を満たす、希土類酸化物粉末。
(I)40W、5分間の超音波分散処理して測定した、レーザー回折・散乱式粒度分布測定法による累積体積100容量%における体積累積粒径D100が1μm以上10μm以下である。
(II)前記希土類酸化物の真密度をρ(g/cm3)としたとき、初期嵩密度ADより下記式1にて算出される空隙率PAD(%)と、タップ嵩密度TDから下記式2で算出される空隙率PTD(%)の差(PAD-PTD)が2.0%以上5.0%以下である。
式1:PAD=(1-AD/ρ) ×100 (%)
式2:PTD=(1-TD/ρ) ×100 (%)
〔a2〕上記(I)に該当する、請求項1に記載の希土類酸化物粉末。
〔a3〕前記希土類酸化物の真密度をρ(g/cm3)としたとき、初期嵩密度ADより下記式1にて算出される空隙率PAD(%)が90.0%以上99.0%以下である、〔a1〕又は〔a2〕に記載の希土類酸化物粉末。
式1:PAD=(1-AD/ρ) ×100 (%)
〔a4〕一次粒子径が35nm以下である、〔a1〕~〔a3〕の何れか1項に記載の希土類酸化物粉末。
〔a5〕Zr含有量が100質量ppm以下である、〔a1〕~〔a4〕の何れか1項に記載の希土類酸化物粉末。
〔a6〕炭素含有量が2質量%以下である、〔a1〕~〔a5〕の何れか1項に記載の希土類酸化物粉末。
〔a7〕上記(II)に該当する、〔a1〕に記載の希土類酸化物粉末。
〔a8〕上記空隙率PAD(%)が90.0%以上99.0%以下である、〔a7〕に記載の希土類酸化物粉末。
〔a9〕40W、5分間の超音波分散処理して測定した、レーザー回折散乱式粒度分布測定法による累積体積100容量%における体積累積粒径D100が1μm以上10μm以下であって、該D100と超音波分散処理して測定し、上記測定法による累積体積50容量%における体積累積粒径D50との比であるD100/D50が、3.0以上11.0以下である〔a7〕又は〔a8〕に記載の希土類酸化物粉末。
The first invention is based on the above findings and provides the following [a1] to [a9].
[a1] A powder of an oxide of at least one rare earth element other than Ce,
A rare earth oxide powder having a primary particle diameter of 10 nm or more and 60 nm or less and satisfying the following (I) or (II):
(I) The volume cumulative particle size D 100 at 100% cumulative volume measured by a laser diffraction/scattering particle size distribution measurement method after ultrasonic dispersion treatment at 40 W for 5 minutes is 1 μm or more and 10 μm or less.
(II) When the true density of the rare earth oxide is ρ (g/ cm3 ), the difference (P AD - P TD ) between the porosity P AD (%) calculated from the initial bulk density AD using the following formula 1 and the porosity P TD (%) calculated from the tapped bulk density TD using the following formula 2 is 2.0% or more and 5.0% or less.
Formula 1: P AD = (1 - AD / ρ) × 100 (%)
Formula 2: P TD = (1 - TD / ρ) × 100 (%)
[a2] The rare earth oxide powder according to claim 1, which corresponds to (I) above.
[a3] The rare earth oxide powder according to [a1] or [a2], wherein when the true density of the rare earth oxide is ρ (g/cm 3 ), the porosity P AD (%) calculated from the initial bulk density AD by the following formula 1 is 90.0% or more and 99.0% or less.
Formula 1: P AD = (1 - AD / ρ) × 100 (%)
[a4] The rare earth oxide powder according to any one of [a1] to [a3], having a primary particle diameter of 35 nm or less.
[a5] The rare earth oxide powder according to any one of [a1] to [a4], wherein the Zr content is 100 ppm by mass or less.
[a6] The rare earth oxide powder according to any one of [a1] to [a5], having a carbon content of 2 mass% or less.
[a7] The rare earth oxide powder according to [a1], which corresponds to the above (II).
[a8] The rare earth oxide powder according to [a7], wherein the porosity P AD (%) is 90.0% or more and 99.0% or less.
[a9] The rare earth oxide powder according to [a7] or [a8], wherein the volume cumulative particle size D100 at 100% cumulative volume, as measured after ultrasonic dispersion treatment at 40 W for 5 minutes, is 1 μm or more and 10 μm or less, as determined by a laser diffraction/scattering particle size distribution measurement method, and the ratio D100 to the volume cumulative particle size D50 at 50 % cumulative volume, as measured after ultrasonic dispersion treatment, as determined by the above measurement method, is 3.0 or more and 11.0 or less.
特許文献1~3、非特許文献1等に示されたような、走査型電子顕微鏡(SEM)による観察において見た目では凝集が少ないように見える希土類酸化物微粉末であっても、一次粒子が数十nmまで小さくなると凝集力が強く、スラリー中で分散させるためには分散剤を使用して湿式解砕する必要がある。
また、上記の事情から、分散剤を用いなくても希土類酸化物微粉末のスラリーを高分散状態にできることが好ましい。
しかしながら、従来、分散剤を用いないでスラリー中の希土類酸化物微粉末を高分散状態にすることは難しく、加えて分散状態を安定的に維持することはさらに難しかった。
特に、Ce以外の希土類元素の酸化物の微粉末は、分散剤を用いずに高分散スラリーとすることは難しかった。
Even in rare earth oxide fine powders that appear to have little aggregation when observed with a scanning electron microscope (SEM) as shown in Patent Documents 1 to 3, Non-Patent Document 1, etc., when the primary particles are as small as several tens of nm, the cohesive force is strong and wet dispersing using a dispersant is required to disperse the particles in a slurry.
In view of the above circumstances, it is preferable that the slurry of the rare earth oxide fine powder can be made to be in a highly dispersed state without using a dispersant.
However, it has been difficult to achieve a high dispersion state of the rare earth oxide fine powder in the slurry without using a dispersant, and it has been even more difficult to stably maintain the dispersion state.
In particular, it has been difficult to prepare a highly dispersed slurry of fine powders of oxides of rare earth elements other than Ce without using a dispersant.
従って第2発明の課題は、分散剤を用いずに高分散スラリーにすることができ、そのスラリーの透明度を安定して保つことができる微粒のCe以外の希土類元素の酸化物粉末を提供することにある。 Therefore, the object of the second invention is to provide a fine oxide powder of a rare earth element other than Ce that can be made into a highly dispersed slurry without using a dispersant and that can stably maintain the transparency of the slurry.
本発明者は鋭意検討したところ、特定の一次粒子径を有し、且つ細孔容量/細孔容積と真密度の掛け合わせた値を特定の範囲とすることで、驚くべきことに、上記課題を解決できることを見出した。After extensive research, the inventors have surprisingly found that the above problems can be solved by having a specific primary particle diameter and by setting the product of the pore volume/pore volume and true density within a specific range.
第2発明は、前記知見に基づくものであり、以下の〔b1〕~〔b7〕を提供するものである。The second invention is based on the above findings and provides the following [b1] to [b7].
〔b1〕Ce以外の少なくとも1種の希土類元素の酸化物の粉末であって、
一次粒子径が10nm以上100nm未満であり、下記(III)及び(IV)を満たす。
(III)細孔直径0.005μm以上100μm以下の細孔容積(cm3/g)に真密度(g/cm3)を掛けて得られる数値が3以上14以下である。
(IV)細孔直径5nm以上50nm以下の細孔容積(cm3/g)に真密度(g/cm3)を掛けて得られる数値が0以上2.0以下である。
〔b2〕Na含有量が10質量ppm以下である、〔b1〕に記載の希土類酸化物粉末。
〔b3〕結晶子径が6nm以上25nm以下である、〔b1〕又は〔b2〕に記載の希土類酸化物粉末。
〔b4〕希土類酸化物粉末をエタノールと混合して希土類酸化物粉末を10質量%含有するエタノールスラリーとした後、以下(A)の操作を、平均粒子径が前回測定値より大きくなるまで繰り返し行ったときに、最小となる平均粒子径が10nm以上150nm以下となる、〔b1〕から〔b3〕のいずれか1項に記載の希土類酸化物粉末。
(A):直径0.1mmのジルコニア製ビーズを用いて、スラリーを10分間のビーズミル処理を行い、その後、平均粒子径を測定する。
(ただし、平均粒子径が前回測定値より大きくなった場合にその時点でビーズミル処理を終了し、20回(A)を繰り返して2回目から20回目までの各回において前回測定値より平均粒子径が大きくならない場合も、20回(A)を繰り返した時点で終了する。ここで最小となる平均粒子径とは、前記(A)の処理毎にサンプリングして測定した動的光散乱法による平均粒子径の最小値の意味である。)。
〔b5〕下記式の計算値が-15%以上25%以下である、〔b4〕に記載の希土類酸化物粉末。
〔b6〕前記ビーズミル処理を行い最小となる平均粒子径が50nm以上90nm以下である〔b4〕又は〔b5〕に記載の希土類酸化物粉末。
〔b7〕〔b1〕~〔b6〕の何れか1項に記載の希土類酸化物粉末を、溶媒を用いて湿式解砕するスラリーの製造方法。
[b1] A powder of an oxide of at least one rare earth element other than Ce,
The primary particle size is 10 nm or more and less than 100 nm, and the following (III) and (IV) are satisfied.
(III) The value obtained by multiplying the pore volume (cm 3 /g) of pores having diameters of 0.005 μm or more and 100 μm or less by the true density (g/cm 3 ) is 3 or more and 14 or less.
(IV) The value obtained by multiplying the volume (cm 3 /g) of pores having a diameter of 5 nm or more and 50 nm or less by the true density (g/cm 3 ) is 0 or more and 2.0 or less.
[b2] The rare earth oxide powder according to [b1], having a Na content of 10 ppm by mass or less.
[b3] The rare earth oxide powder according to [b1] or [b2], having a crystallite size of 6 nm or more and 25 nm or less.
[b4] The rare earth oxide powder according to any one of [b1] to [b3], in which when the rare earth oxide powder is mixed with ethanol to prepare an ethanol slurry containing 10 mass% of the rare earth oxide powder, and the following operation (A) is repeatedly performed until the average particle diameter becomes larger than the previous measurement value, the smallest average particle diameter is 10 nm or more and 150 nm or less.
(A): The slurry is subjected to a bead mill treatment for 10 minutes using zirconia beads having a diameter of 0.1 mm, and then the average particle size is measured.
(However, if the average particle diameter becomes larger than the previous measurement, the bead mill treatment is terminated at that point, and even if the average particle diameter does not become larger than the previous measurement in each of the second to twentieth repetitions of (A) 20 times, the treatment is terminated when (A) has been repeated 20 times. The minimum average particle diameter here means the minimum value of the average particle diameter measured by dynamic light scattering method by sampling after each treatment of (A).)
[b5] The rare earth oxide powder according to [b4], wherein the calculated value of the following formula is −15% or more and 25% or less.
[b6] The rare earth oxide powder according to [b4] or [b5], wherein the minimum average particle size obtained by the bead mill treatment is 50 nm or more and 90 nm or less.
[b7] A method for producing a slurry, comprising wet-grinding the rare earth oxide powder according to any one of [b1] to [b6] using a solvent.
以下、本明細書では、「希土類元素の酸化物」を「希土類酸化物」と記載することがある。
以下、第1発明をその好ましい実施形態に基づき詳細に説明する。
第1発明は、Ce以外の希土類元素の酸化物の粉末に係るものである。
Ceの酸化物であるCeO2は、水中の水酸化セリウムに酸化剤(H2O2)を添加することにより未焼成で得られ、またCeが酸化しやすいために前駆体を低温で焼成しても容易に得られる。このことから、CeO2は製造時の焼成に起因した凝集の影響が少なく、一次粒子が数十nmの粉末であっても容易に解砕することができる。
一方、Ce以外の希土類元素は水酸化物に酸化剤を添加しても未焼成ではCeのような酸化物にはならない。また、通常、製造には前駆体を比較的高温で焼成することが必須であり、高温焼成はネッキングの一因となる。それゆえに従来Ce以外の希土類元素粉末では、一次粒子が数十nmである場合、粉末の凝集抑制が非常に困難であった。
Hereinafter, in this specification, the "oxide of a rare earth element" may be referred to as the "rare earth oxide".
The first aspect of the invention will now be described in detail based on its preferred embodiments.
The first invention relates to a powder of an oxide of a rare earth element other than Ce.
CeO2 , an oxide of Ce, can be obtained unsintered by adding an oxidizing agent ( H2O2 ) to cerium hydroxide in water, and can also be easily obtained by sintering the precursor at a low temperature because Ce is easily oxidized. For this reason, CeO2 is less susceptible to agglomeration caused by sintering during production, and can be easily disintegrated even if it is a powder with primary particles of several tens of nanometers.
On the other hand, rare earth elements other than Ce do not become oxides like Ce when not fired even if an oxidizing agent is added to the hydroxide. In addition, the precursor usually needs to be fired at a relatively high temperature for production, and high-temperature firing is one of the causes of necking. Therefore, in the conventional rare earth element powders other than Ce, it was very difficult to suppress the aggregation of the powder when the primary particles were several tens of nm.
第1発明において希土類元素の酸化物としては、Sc、Y、La、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb及びLuから選ばれる少なくとも一種の酸化物が挙げられる。具体的には、Ce以外の希土類元素の酸化物としては、Sc2O3、Y2O3、La2O3、Pr6O11、Nd2O3、Sm2O3、Eu2O3、Gd2O3、Tb4O7、Dy2O3、Ho2O3、Er2O3、Tm2O3、Yb2O3及びLu2O3が挙げられる。従来の凝集抑制の困難さによる第1発明の効果の意義に優れる点から、希土類元素の酸化物としては、好ましくは、Y、La、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb及びLuから選ばれる少なくとも一種の酸化物であり、より好ましくはY、Nd、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb及びLuから選ばれる少なくとも一種の酸化物であり、更に好ましくはY、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb及びLuから選ばれる少なくとも一種の酸化物であり、特に好ましくはY、Dy、Ho、Er及びYbから選ばれる少なくとも一種の酸化物である。 In the first invention, the oxide of a rare earth element may be at least one oxide selected from Sc, Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. Specifically, the oxide of a rare earth element other than Ce may be Sc2O3 , Y2O3 , La2O3 , Pr6O11 , Nd2O3 , Sm2O3 , Eu2O3 , Gd2O3 , Tb4O7 , Dy2O3 , Ho2O3 , Er2O3 , Tm2O3 , Yb2O3 , and Lu2O3 . In view of the excellent significance of the effect of the first invention due to the conventional difficulty in suppressing aggregation, the oxide of a rare earth element is preferably at least one oxide selected from Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, more preferably at least one oxide selected from Y, Nd, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, even more preferably at least one oxide selected from Y, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, and particularly preferably at least one oxide selected from Y, Dy, Ho, Er and Yb.
希土類酸化物粉末の一次粒子径は所定範囲が好ましい。希土類元素の酸化物粉末では一次粒子径は小さい方が熱拡散は良くなるが、小さすぎると凝集が強くなり、容易に解砕できなくなる。一方、一次粒子径が大きすぎてもネッキングが発生して凝集径が大きくなるほか、希土類酸化物粉末をビーズミル等で解砕する際に粒子が粉砕され活性面が増えて不安定なスラリーをもたらす。これらの点から、第1発明では、希土類酸化物粉末の一次粒子径は10nm以上60nm以下が好ましく、15nm以上60nm以下がより好ましく、更に好ましくは15nm以上35nm以下である。希土類酸化物粉末の一次粒子径が35nm以下であることは、コーティング液としたときの塗膜性の向上や希土類酸化物粉末の熱拡散が大きい点で特に好ましい。The primary particle diameter of the rare earth oxide powder is preferably within a certain range. In rare earth oxide powder, the smaller the primary particle diameter, the better the thermal diffusion, but if it is too small, the stronger the aggregation and the more difficult it is to disintegrate. On the other hand, if the primary particle diameter is too large, necking occurs and the aggregate diameter becomes large, and when the rare earth oxide powder is disintegrated with a bead mill or the like, the particles are crushed, increasing the active surface and resulting in an unstable slurry. From these points, in the first invention, the primary particle diameter of the rare earth oxide powder is preferably 10 nm or more and 60 nm or less, more preferably 15 nm or more and 60 nm or less, and even more preferably 15 nm or more and 35 nm or less. A primary particle diameter of 35 nm or less of the rare earth oxide powder is particularly preferable in terms of improving the coating properties when used as a coating liquid and the large thermal diffusion of the rare earth oxide powder.
第1発明において、希土類元素の酸化物粉末の一次粒子径は、比表面積換算の一次粒子径であり、具体的には、BET1点法より測定された比表面積s(m2/g)から求めた粒径である。例えば、一次粒子径d(nm)はd=6000/(ρs)である。(ρは真密度(g/cm3))。 In the first invention, the primary particle diameter of the rare earth oxide powder is the primary particle diameter calculated based on the specific surface area, specifically, the particle diameter calculated from the specific surface area s ( m2 /g) measured by the BET single point method. For example, the primary particle diameter d (nm) is d = 6000/(ρs) (ρ is the true density (g/ cm3 )).
第1発明の希土類元素の酸化物粉末の比表面積は、例えば、10m2/g以上160m2/g以下が好ましく、15m2/g以上110m2/g以下が更に好ましく、20m2/g以上80m2/g以下が特に好ましい。 The specific surface area of the rare earth oxide powder of the first invention is, for example, preferably from 10 to 160 m 2 /g, more preferably from 15 to 110 m 2 /g, and particularly preferably from 20 to 80 m 2 / g.
第1発明では、超音波照射後に、レーザー回折散乱式粒度分布測定法で測定した体積基準のD100(累積体積100容量%における体積累積粒径)が特定範囲であることが薄膜を塗膜可能とする点から好ましい。例えば塗膜性の観点から超音波照射後のD100は10μm以下が特に好ましく、9μm以下がより好ましく、7μm以下が更に一層好ましい。薄膜を作製するためには、大きな粗大粒子があると塗膜できない。また、スラリーの分散性が良すぎると、スラリーの安定性が悪く、凝集することがある。そうすると、粘度等の物性も変化し、塗膜条件も変わる。安定性の観点から、上記のD100は1μm以上であることが好ましく、2μm以上がより好ましい。 In the first invention, it is preferable that the volume-based D 100 (volume cumulative particle size at 100% cumulative volume) measured by a laser diffraction scattering type particle size distribution measurement method after ultrasonic irradiation is within a specific range in order to enable a thin film to be coated. For example, from the viewpoint of coating properties, D 100 after ultrasonic irradiation is particularly preferably 10 μm or less, more preferably 9 μm or less, and even more preferably 7 μm or less. In order to produce a thin film, coating is not possible if there are large coarse particles. In addition, if the dispersibility of the slurry is too good, the stability of the slurry is poor and it may aggregate. This will change the physical properties such as viscosity, and the coating conditions will also change. From the viewpoint of stability, the above D 100 is preferably 1 μm or more, and more preferably 2 μm or more.
上記の超音波照射とは、より具体的には、40Wの超音波、周波数40kHzにて5分間分散させる処理である。照射装置としては、レーザー回折散乱式粒子径測定装置に付属のものが挙げられ、例えば0.2質量%ヘキサメタリン酸ナトリウム水溶液に希土類酸化物粉末を添加した試料に照射されるものである。超音波照射時の分散液中の希土類酸化物粉末の濃度は、粒子径測定装置が粒径測定の適正濃度と判断した濃度が好ましく挙げられ、通常0.002~0.2質量%の範囲内である。超音波照射は具体的には実施例に記載の方法にて行われるが、同等の照射装置であれば、測定に用いるレーザー回折散乱式粒子径測定装置に付属のもの以外の装置で照射を行ってもよい。ただし、測定に用いるレーザー回折散乱式粒子径測定装置に付属のもの以外の装置を用いて照射を行う場合は、約100mlの0.2質量%のヘキサメタリン酸ナトリウム水溶液に、0.2gの試料を入れ、超音波照射後、超音波照射後のスラリーを試料循環装置に粒子径測定装置が粒径測定の適正濃度と判断するまで添加した後、測定を実施する。More specifically, the ultrasonic irradiation is a process of dispersing the sample with 40 W ultrasonic waves at a frequency of 40 kHz for 5 minutes. The irradiation device may be an attachment to a laser diffraction scattering type particle size measuring device, and may be irradiated to a sample in which rare earth oxide powder has been added to a 0.2% by mass aqueous solution of sodium hexametaphosphate. The concentration of the rare earth oxide powder in the dispersion liquid during ultrasonic irradiation is preferably a concentration that the particle size measuring device judges to be an appropriate concentration for particle size measurement, and is usually in the range of 0.002 to 0.2% by mass. The ultrasonic irradiation is specifically performed according to the method described in the examples, but irradiation may be performed using a device other than that attached to the laser diffraction scattering type particle size measuring device used for measurement, as long as it is an equivalent irradiation device. However, when irradiation is performed using a device other than that attached to the laser diffraction scattering type particle size measuring device used for measurement, 0.2 g of the sample is placed in about 100 ml of a 0.2% by mass aqueous solution of sodium hexametaphosphate, and after ultrasonic irradiation, the slurry after ultrasonic irradiation is added to the sample circulation device until the particle size measuring device judges it to be an appropriate concentration for particle size measurement, and then the measurement is performed.
更に一層塗膜性を高める点、及び塗工の容易性の点から、第1発明の粒子は、上記の超音波照射後のレーザー回折散乱式粒度分布測定法で測定した体積基準のD90(累積体積90容量%における体積累積粒径)が0.1μm以上2.5μm以下であることが好ましく、0.3μm以上2.3μm以下であることが更に一層好ましく、0.5μm以上2.0μm以下であることが特に好ましい。 From the standpoint of further improving the coatability and ease of coating, the particles of the first invention preferably have a volume-based D90 (volume cumulative particle size at 90 volume % cumulative volume) measured by a laser diffraction scattering particle size distribution measurement method after the above-mentioned ultrasonic irradiation of 0.1 μm or more and 2.5 μm or less, even more preferably 0.3 μm or more and 2.3 μm or less, and particularly preferably 0.5 μm or more and 2.0 μm or less.
また更に一層塗膜性を高める点、及び塗工の容易性の点から、第1発明の粒子は、上記の超音波照射後のレーザー回折散乱式粒度分布測定法で測定した体積基準のD50(累積体積50容量%における体積累積粒径)が0.3μm以上1.2μm以下であることが好ましく、0.5μm以上1.0μm以下であることが更に好ましく、0.5μm以上0.7μm以下であることがより好ましい。 From the viewpoint of further improving the coatability and ease of coating, the particles of the first invention preferably have a volume-based D50 (volume cumulative particle size at 50 volume % cumulative volume) measured by the laser diffraction scattering particle size distribution measurement method after the above-mentioned ultrasonic irradiation of 0.3 μm or more and 1.2 μm or less, more preferably 0.5 μm or more and 1.0 μm or less, and even more preferably 0.5 μm or more and 0.7 μm or less.
塗膜性の観点からD100/D50が特定の範囲である粒度分布であることが特に好ましい。具体的にはD100/D50が3.0以上11.0以下が好ましく、3.0以上8.5以下がより好ましい。 From the viewpoint of film-forming properties , it is particularly preferable that the particle size distribution has a specific range of D100/D50.Specifically, D100 /D50 is preferably 3.0 or more and 11.0 or less, and more preferably 3.0 or more and 8.5 or less.
希土類酸化物粉末の不純物量は少ない方が好ましい。特にビーズミルのビーズなどの粉砕メディアを使用すれば、D100を1~20μm、より好適には10μmまで容易に解砕することができるが、メディアが不純物となりコンタミする。第1発明では、上記メディアを使用せずに希土類酸化物粉末を製造できるため、粉砕メディアの構成元素として一般に使用されるZr元素を100質量ppm以下にすることが可能である。さらに10質量ppm以下にすることも容易であり、2質量ppm以下とすることもできる。このような希土類酸化物粉末は、コンタミネーションのリスク低減の点で好ましく、電子部品や半導体製造装置用耐食材料等の用途にも好適である。Zr元素の含有量はICP発光分析法により測定でき、後述する実施例に記載の方法にて測定することができる。測定サンプルは常法にて調製でき、例えば希土類酸化物粉末を硝酸又は硫酸で溶解することで調製できる。 The rare earth oxide powder preferably has a small amount of impurities. In particular, by using a grinding media such as beads of a bead mill, D 100 can be easily crushed to 1 to 20 μm, more preferably 10 μm, but the media become impurities and cause contamination. In the first invention, since the rare earth oxide powder can be produced without using the above-mentioned media, it is possible to reduce the Zr element, which is generally used as a constituent element of the grinding media, to 100 mass ppm or less. It is also easy to reduce it to 10 mass ppm or less, and it can also be reduced to 2 mass ppm or less. Such rare earth oxide powder is preferable in terms of reducing the risk of contamination, and is also suitable for applications such as corrosion-resistant materials for electronic components and semiconductor manufacturing equipment. The content of the Zr element can be measured by ICP emission spectrometry, and can be measured by the method described in the examples below. The measurement sample can be prepared by a conventional method, for example, by dissolving the rare earth oxide powder in nitric acid or sulfuric acid.
希土類酸化物粉末の炭素含有量は少ない方が好ましい。希土類元素やその化合物は固溶を目的として添加材としても頻繁に使用される。炭素成分があると、焼成時に質量減少(体積変化)が生じて膜のひび割れなどが発生する。そのため、炭素含有量は2質量%以下が好ましい。より好ましくは1質量%以下であり、特に好ましくは0.7質量%以下である。炭素含有量は後述する実施例に記載の方法にて測定することができる。
なお希土類酸化物粉末は純度が通常99質量%以上のものであることが好ましい。例えば、Zr及び炭素含有量の合計が1質量%以下であることが好ましい。
The carbon content of the rare earth oxide powder is preferably low. Rare earth elements and their compounds are frequently used as additives for the purpose of solid solution. If carbon components are present, mass reduction (volume change) occurs during firing, causing film cracks, etc. Therefore, the carbon content is preferably 2 mass% or less, more preferably 1 mass% or less, and particularly preferably 0.7 mass% or less. The carbon content can be measured by the method described in the examples below.
The rare earth oxide powder preferably has a purity of 99% by mass or more. For example, the total content of Zr and carbon is preferably 1% by mass or less.
本発明者はSSA換算の一次粒子径が所定範囲内である希土類酸化物粉末の分散容易性にとって、初期嵩密度(AD)から式1で得られる空隙率PAD(%)と、タップ嵩密度(TD)から式2で得られる空隙率PTD(%)との差(PAD-PTD)(%)が所定範囲であることが特に好ましいことを見出した。ρは真密度である。
式1:PAD=(1-AD/ρ) ×100 (%)
式2:PTD=(1-TD/ρ) ×100 (%)
The present inventors have found that for the ease of dispersion of a rare earth oxide powder having a primary particle size in terms of SSA within a predetermined range, it is particularly preferable that the difference (P AD - P TD ) (%) between the porosity P AD (%) obtained from the initial bulk density (AD) using Equation 1 and the porosity P TD (%) obtained from the tapped bulk density ( TD ) using Equation 2 be within a predetermined range, where ρ is the true density.
Formula 1: P AD = (1 - AD / ρ) × 100 (%)
Formula 2: P TD = (1 - TD / ρ) × 100 (%)
(PAD-PTD)(%)の値が大きいことは、タップ嵩密度測定によるタップにより、空隙が詰まりやすいことを意味する。(PAD-PTD)(%)の値が大きすぎる粒子、つまり、圧縮でき過ぎる粉末は凝集が強い粉末となる。一方、(PAD-PTD)(%)の値が小さすぎる粉末は粒子間の空気が多い状態であり、その状態で容易に圧縮され難い比較的フワフワした粉末であることを意味する。そのような粉末は粒子間に空気を抱き込んで凝集径が大きくなる傾向にある。これらのことから圧縮の程度のバランスが希土類酸化物微粉末の凝集しやすさを左右するとの推測に基づき本発明者は検討した結果、当該パラメータが希土類酸化物粉末の分散しやすさに影響することを見出した。
具体的には、(PAD-PTD)(%)の差は、2.0%以上5.0%以下であることが好ましい。(PAD-PTD)(%)が2.0%以上5.0%以下であることで、圧縮しやすさが適度となり、当該範囲外の粉末に比して分散容易性に優れ、コーティング液としたときの塗膜性に優れる。この観点から、(PAD-PTD)(%)が3.0%以上5.0%以下であることがより好適であり、3.0%以上4.5%以下であることが更に好適である。
A large value of (P AD - P TD ) (%) means that the voids are easily clogged by tapping in tap bulk density measurement. Particles with too large a value of (P AD - P TD ) (%), that is, powders that can be compressed too easily, are powders with strong agglomeration. On the other hand, powders with too small a value of (P AD - P TD ) (%) mean that there is a lot of air between the particles, and that the powder is relatively fluffy and difficult to compress in that state. Such powders tend to trap air between the particles, resulting in large agglomeration diameters. Based on these facts, the inventors conducted research based on the assumption that the balance of the degree of compression affects the ease of agglomeration of rare earth oxide fine powders, and as a result, they found that this parameter affects the ease of dispersion of rare earth oxide powders.
Specifically, the difference between (P AD - P TD ) (%) is preferably 2.0% or more and 5.0% or less. By having (P AD - P TD ) (%) of 2.0% or more and 5.0% or less, the powder has a suitable degree of compressibility, is excellent in dispersibility compared to powders outside this range, and has excellent coatability when made into a coating liquid. From this viewpoint, it is more preferable that (P AD - P TD ) (%) is 3.0% or more and 5.0% or less, and even more preferable that it is 3.0% or more and 4.5% or less.
更に、凝集抑制と取扱い性のバランスを鑑みて初期嵩密度から計算される空隙率PAD(%)は、90.0%以上99.0%以下が好ましく、92.0%以上98.0%以下がより好ましい。上記の(PAD-PTD)(%)を有し、且つPAD(%)が92.0%以上98.0%以下であることは、凝集性が特に適度であるために分散しやすい点で好ましい。
また、同様の観点から、タップ嵩密度から計算されるPTDは88.0%以上95.5%以下が好ましく、88.5%以上92.0%以下がより好ましい。
Furthermore, in consideration of the balance between inhibition of aggregation and ease of handling, the porosity P AD (%) calculated from the initial bulk density is preferably 90.0% or more and 99.0% or less, and more preferably 92.0% or more and 98.0% or less. Having the above (P AD -P TD ) (%) and having P AD (%) of 92.0% or more and 98.0% or less is preferable in that the aggregation property is particularly moderate and therefore dispersion is easy.
From the same viewpoint, P TD calculated from the tapped bulk density is preferably 88.0% or more and 95.5% or less, and more preferably 88.5% or more and 92.0% or less.
上述した比表面積(m2/g)、一次粒子径(nm)、粒度分布、初期嵩密度(AD)及びタップ嵩密度(TD)、Zr含有量、炭素含有量、PAD、PTD及びPAD-PTDを得るためには、後述する好適な希土類酸化物粉末の製造方法を採用し、混合、洗浄又は焼成の条件を調整すればよい。 In order to obtain the above-mentioned specific surface area ( m2 /g), primary particle diameter (nm), particle size distribution, initial bulk density (AD), tapped bulk density (TD), Zr content, carbon content, P AD , P TD and P AD -P TD , a suitable method for producing rare earth oxide powder described below may be adopted and the mixing, washing or firing conditions may be adjusted.
次いで第1発明の希土類酸化物粉末の好適な製造方法について説明する。
本製造方法は、炭酸塩水溶液(以下「A液」ともいう。)と希土類元素の水溶性塩水溶液(以下「B液」ともいう。)とを反応槽を同時に投入して、混合液のpHが6.5~7.0、好ましくは6.5~6.9となるように高速撹拌下に混合して炭酸塩と希土類元素の水溶性塩とを反応させ、A液とB液の混合開始から5分以内に固液分離を開始する反応・固液分離工程と、反応・固液分離工程で得られた残渣をアルコールで洗浄する洗浄工程と、洗浄した残渣を、焼成する焼成工程とを含むものである。
第1発明の希土類酸化物粉末を首尾よく得る点から、好適には、B液である希土類元素の水溶性塩水溶液における酸化物換算の水溶性塩濃度が酸化物換算で10~400g/Lであり、50~350g/Lであることがより好ましく、特に好適には80~300g/Lであり、最も好ましくは100g/L超300g/L以下である。
Next, a preferred method for producing the rare earth oxide powder of the first invention will be described.
This production method includes a reaction/solid-liquid separation step in which an aqueous carbonate solution (hereinafter also referred to as "liquid A") and an aqueous water-soluble salt solution of a rare earth element (hereinafter also referred to as "liquid B") are simultaneously charged into a reaction tank and mixed with high speed stirring so that the pH of the mixed solution becomes 6.5 to 7.0, preferably 6.5 to 6.9, to react the carbonate with the water-soluble salt of the rare earth element, and solid-liquid separation begins within 5 minutes from the start of mixing of liquids A and B; a washing step in which the residue obtained in the reaction/solid-liquid separation step is washed with alcohol; and a calcination step in which the washed residue is calcined.
In order to successfully obtain the rare earth oxide powder of the first invention, the water-soluble salt concentration, calculated as the oxide, in the water-soluble salt aqueous solution of the rare earth element, which is Liquid B, is preferably 10 to 400 g/L, more preferably 50 to 350 g/L, particularly preferably 80 to 300 g/L, and most preferably more than 100 g/L but not more than 300 g/L.
(反応・固液分離工程)
炭酸塩水溶液であるA液において、炭酸塩は、炭酸水素アンモニウム、炭酸アンモニウム、炭酸ナトリウム、炭酸水素ナトリウム等が挙げられる。本明細書でいう炭酸塩とは正塩だけでなく酸性塩である炭酸水素塩を含む。混合液のpHの調整が容易な点やナトリウム含量を低減する点から、炭酸水素アンモニウムが好ましい。
希土類元素の水溶性塩水溶液であるB液において、希土類元素の水溶性塩としては、硝酸塩、酢酸塩、アンミン錯体、塩化物が挙げられ、混合液のpHの調整が容易な点や生産性の観点から硝酸塩が好ましい。
(Reaction and solid-liquid separation process)
In the solution A which is an aqueous carbonate solution, examples of the carbonate include ammonium hydrogen carbonate, ammonium carbonate, sodium carbonate, sodium hydrogen carbonate, etc. In this specification, carbonate includes not only normal salts but also hydrogen carbonate which is an acidic salt. Ammonium hydrogen carbonate is preferred from the viewpoints of easy adjustment of the pH of the mixed solution and reduction of the sodium content.
In the solution B, which is an aqueous solution of a water-soluble salt of a rare earth element, examples of the water-soluble salt of the rare earth element include nitrates, acetates, ammine complexes, and chlorides. Nitrates are preferred from the viewpoints of ease of adjusting the pH of the mixed solution and productivity.
本製造方法において、炭酸塩水溶液であるA液と希土類元素の水溶性塩水溶液であるB液とは両者の混合液のpHが6.5~7.0、好ましくは6.5~6.9となるように反応槽に同時に投入される。ここでいうpHは両者の混合液の温度でのpHである。混合液のpHが7.0超となると、一次粒子が大きなものとなってしまう。またpHを6.5以上とすることはA液中の希土類イオンがほぼ全て沈殿する利点がある。A液及びB液はいずれも投入時点で加温しないことが好ましい。A液及びB液は、反応槽への投入時点で5~50℃であることが好適であり、混合液の温度は5~40℃であることが好適である。一次粒子径を好適な範囲内とするために、反応を極短時間で行い、すぐに濾過することが好ましい。このために、混合液のpHは、A液及びB液の反応槽の投入開始時点(A液とB液との混合開始時点)から反応生成物が生じる時点(より具体的には固液分離開始時点)まで6.5~7.0の範囲内であるように両液の投入のタイミング及び投入速度を調整して、pHを上記範囲に一定に維持することが好適である。pHが上記範囲となることで反応進行がスムーズに起こる。In this manufacturing method, liquid A, which is an aqueous carbonate solution, and liquid B, which is an aqueous solution of a water-soluble salt of a rare earth element, are simultaneously introduced into a reaction vessel so that the pH of the mixture of the two is 6.5 to 7.0, preferably 6.5 to 6.9. The pH here is the pH at the temperature of the mixture of the two. If the pH of the mixture exceeds 7.0, the primary particles will become large. In addition, setting the pH at 6.5 or higher has the advantage that almost all of the rare earth ions in liquid A will precipitate. It is preferable that neither liquid A nor liquid B is heated at the time of introduction. It is preferable that liquid A and liquid B are 5 to 50°C at the time of introduction into the reaction vessel, and the temperature of the mixture is 5 to 40°C. In order to keep the primary particle size within a suitable range, it is preferable to carry out the reaction in an extremely short time and filter it immediately. For this reason, it is preferable to adjust the timing and rate of introduction of both liquids so that the pH of the mixed liquid is within the range of 6.5 to 7.0 from the time when the introduction of liquid A and liquid B into the reaction vessel starts (the time when mixing of liquid A and liquid B starts) to the time when the reaction product is generated (more specifically, the time when solid-liquid separation starts), thereby maintaining the pH constant within the above range. The reaction proceeds smoothly when the pH is within the above range.
A液とB液とが同時に添加されるとは、反応槽においてA液が投入される時点と、B液が投入される時点とが一部でも同時となることを意味する。上述した通り、混合液のpHが、A液及びB液の反応槽の投入開始時点(A液とB液との混合開始時点)から反応生成物が生じる時点(より具体的には固液分離開始時点)まで6.5~7.0の範囲内であるためには、それぞれの投入開始をほぼ同時とし、投入速度を一定とすることが好ましい。またA液とB液の投入速度は、A液とB液の混合開始から5分以内、より好適には3分以内に固液分離を開始できるように調整する。The simultaneous addition of liquid A and liquid B means that the time when liquid A is added to the reaction vessel and the time when liquid B is added are at least partially simultaneous. As described above, in order for the pH of the mixed liquid to be within the range of 6.5 to 7.0 from the time when liquid A and liquid B start to be added to the reaction vessel (the time when liquid A and liquid B start to be mixed) to the time when the reaction product is generated (more specifically, the time when solid-liquid separation starts), it is preferable that the start of each addition is almost simultaneous and the addition speed is constant. In addition, the addition speed of liquid A and liquid B is adjusted so that solid-liquid separation can start within 5 minutes, more preferably within 3 minutes, from the start of mixing liquid A and liquid B.
本製造方法では、反応槽においてA液とB液の混合液は上記のように同時に投入されて所定pH条件下で高速撹拌される。このような態様により、上記一次粒子径、超音波照射後の凝集径D100、空隙率差が上記所定範囲である粉末が好適に得やすいものとなる。高速撹拌としては回転数が10,000~25,000rpmの撹拌が挙げられ、18,000~21,000rpmがより好ましい。これらの撹拌は混合液の反応槽における攪拌子が上記回転を行う場合に、反応槽の容量としては50ml~1Lであることが好適であり、100ml~500mlであることがより好適である。
本発明者は反応槽に予め入れておいたA液にB液を添加したり、反応槽に予め入れておいたB液にA液を投入するのではなく、A液とB液を同時投入し、且つ所定pHを維持した条件で高速撹拌することで、短時間で反応を済ませることができ、これを所定の後処理に供すると、一次粒子径が小さく低強度の解砕で簡単に分散可能な第1発明の希土類酸化物粉末を得ることができることを見出した。
In this manufacturing method, the mixed solution of solution A and solution B is simultaneously introduced into the reaction tank as described above and stirred at high speed under a predetermined pH condition. This embodiment makes it easy to obtain a powder having the above-mentioned primary particle size, agglomeration size D 100 after ultrasonic irradiation, and porosity difference within the above-mentioned predetermined range. High-speed stirring can be performed at a rotation speed of 10,000 to 25,000 rpm, and more preferably 18,000 to 21,000 rpm. When the stirrer in the reaction tank of the mixed solution rotates as described above, the capacity of the reaction tank is preferably 50 ml to 1 L, and more preferably 100 ml to 500 ml.
The present inventors have found that, rather than adding liquid B to liquid A that has already been placed in a reaction tank, or pouring liquid A into liquid B that has already been placed in a reaction tank, by simultaneously pouring liquid A and liquid B into the reaction tank and stirring at high speed while maintaining a predetermined pH, the reaction can be completed in a short period of time, and that by subjecting this to a predetermined post-treatment, it is possible to obtain the rare earth oxide powder of the first invention, which has a small primary particle size and can be easily dispersed by low-intensity crushing.
上記一次粒子径、超音波照射後の凝集径D100、空隙率差をより得やすい点から、A液における炭酸塩の濃度は5~25質量%であることが好ましく、10~15質量%であることがより好ましい。またB液における希土類元素の水溶性塩の濃度は上述した通りである。 From the viewpoint of making it easier to obtain the above-mentioned primary particle size, agglomeration size D after ultrasonic irradiation, and porosity difference, the concentration of the carbonate in solution A is preferably 5 to 25 mass %, more preferably 10 to 15 mass %, and the concentration of the water-soluble salt of the rare earth element in solution B is as described above.
(洗浄工程)
上記の固液分離工程で得られた残渣(「固形状物」ともいう。)は、アルコールで洗浄する。本製造方法で用いるアルコールとしては例えばアルコール純度99.5vol%以上である高純度のものが好適に用いられる。アルコールとしては、メタノール、エタノール、イソプロパノール等が挙げられるが、エタノールであることが、使用性の点から好ましい。洗浄に用いるアルコールの量は、使用する希土類酸化物1gに対して、0.1L~50Lであることが好ましく、0.5L~20Lであることがより好ましく、1L~10Lであることが更に好ましい。ここでいう量は、アルコールを数回残渣に通液して洗浄する場合にはその総量である。
(Washing process)
The residue (also referred to as "solid matter") obtained in the solid-liquid separation step is washed with alcohol. The alcohol used in this production method is preferably one having a high purity, for example, an alcohol purity of 99.5 vol% or more. Examples of the alcohol include methanol, ethanol, and isopropanol, and ethanol is preferred from the viewpoint of usability. The amount of alcohol used for washing is preferably 0.1 L to 50 L, more preferably 0.5 L to 20 L, and even more preferably 1 L to 10 L, per 1 g of rare earth oxide used. The amount referred to here is the total amount when the alcohol is passed through the residue several times to wash it.
(焼成工程)
焼成温度は、1000℃以下であることが、凝集抑制の点、及び結晶成長の抑制の点で好ましく、800℃以下であることがより好ましい。焼成温度は、500℃以上であることが、炭素含有量低減の点で好ましい。この観点から、焼成温度は500℃以上1000℃以下であることがより好適であり、500℃以上800℃以下が更に好適である。焼成は、大気雰囲気などの酸素ガス含有雰囲気下、及びアルゴンや窒素などの不活性雰囲気下で行うことができるが、酸素ガス含有雰囲気下、特に大気雰囲気下で行うことが炭素含有量低減及びコストの点で好ましい。
(Firing process)
The firing temperature is preferably 1000° C. or less in terms of suppressing aggregation and suppressing crystal growth, and more preferably 800° C. or less. The firing temperature is preferably 500° C. or more in terms of reducing the carbon content. From this viewpoint, the firing temperature is more preferably 500° C. or more and 1000° C. or less, and even more preferably 500° C. or more and 800° C. or less. The firing can be performed under an oxygen gas-containing atmosphere such as air atmosphere, and an inert atmosphere such as argon or nitrogen, but it is preferable to perform the firing under an oxygen gas-containing atmosphere, particularly air atmosphere, in terms of reducing the carbon content and costs.
(解砕工程)
焼成して得られた希土類酸化物粉末は粗粒を解砕することが好ましい。解砕には、乾式粉砕機を用いることができ、例えば、粉砕機(商品名:フォースミル、大阪ケミカル製)を用いることができる。
(Crushing process)
It is preferable to crush the coarse particles of the rare earth oxide powder obtained by firing. For crushing, a dry crusher can be used, for example, a crusher (product name: Force Mill, manufactured by Osaka Chemical Co., Ltd.).
次いで、上記のようにして得られた希土類酸化物粉末はその分散容易性を生かし、各種用途に用いることができる。例えば、コンデンサー用誘電体あるいは内部電極、蛍光体、光学ガラス用屈折率調整剤、酸素センサー、セラミックスの焼結助剤、合金への添加材、触媒、耐火物、レーザー結晶原料、半導体製造装置用耐食材料等が挙げられる。その際の使用方法は様々であり、コーティング(塗膜形成)、微量添加、成型体(焼結体含む)等の各種形態に適用することができる。特に第1発明の希土類酸化物粉末はその塗膜性が良好であることから、そのコーティング用途(塗膜形成用途を含む)に好適に用いることができる。The rare earth oxide powder obtained as described above can then be used in a variety of applications, taking advantage of its ease of dispersion. Examples include dielectrics or internal electrodes for capacitors, phosphors, refractive index adjusters for optical glass, oxygen sensors, sintering aids for ceramics, additives to alloys, catalysts, refractories, laser crystal raw materials, and corrosion-resistant materials for semiconductor manufacturing equipment. There are various ways to use the powder, and it can be applied to various forms such as coating (film formation), trace addition, and molded bodies (including sintered bodies). In particular, the rare earth oxide powder of the first invention has good film-forming properties and can be suitably used for coating applications (including film formation).
以下、第2発明をその好ましい実施形態に基づき詳細に説明する。
第2発明は、Ce以外の希土類元素の酸化物の粉末に係るものである。
Ceの酸化物であるCeO2は、水中の水酸化セリウムに酸化剤(H2O2)を添加することで焼成工程を経ずに得られ、またCeが酸化しやすいために前駆体を低温で焼成しても容易に得られる。このことから、CeO2は製造時の焼成に起因した凝集の影響が少なく、一次粒子が数十nmの粉末であっても容易に解砕することができる。
一方、Ce以外の希土類元素は水酸化物に酸化剤を添加しても酸化物は得られないことなどから、通常、製造に比較的高温での焼成が必須であり、高温焼成はネッキングの一因となる。それゆえに従来Ce以外の希土類元素粉末では、一次粒子が数十nmである場合、粉末の凝集抑制が非常に困難であった。
The second invention will now be described in detail based on preferred embodiments thereof.
The second invention relates to a powder of an oxide of a rare earth element other than Ce.
CeO2 , an oxide of Ce, can be obtained without a calcination process by adding an oxidizing agent ( H2O2 ) to cerium hydroxide in water, and since Ce is easily oxidized, it can be easily obtained by calcining the precursor at a low temperature. For this reason, CeO2 is less susceptible to agglomeration caused by calcination during production, and can be easily disintegrated even if it is a powder with primary particles of several tens of nanometers.
On the other hand, since rare earth elements other than Ce cannot obtain oxides even if an oxidizing agent is added to their hydroxides, they usually require firing at relatively high temperatures for production, and high-temperature firing is one of the causes of necking. Therefore, in conventional rare earth element powders other than Ce, it has been very difficult to suppress the aggregation of the powder when the primary particles are several tens of nm in size.
第2発明においてCe以外の希土類元素の酸化物としては、Sc、Y、La、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb及びLuから選ばれる少なくとも一種の酸化物が挙げられる。具体的には、Ce以外の希土類元素の酸化物としては、Sc2O3、Y2O3、La2O3、Pr6O11、Nd2O3、Sm2O3、Eu2O3、Gd2O3、Tb4O7、Dy2O3、Ho2O3、Er2O3、Tm2O3、Yb2O3及びLu2O3が挙げられる。従来の凝集抑制の困難さによる第2発明の効果の意義に優れる点から、上記希土類元素の酸化物としては、好ましくは、Y、La、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb及びLuから選ばれる少なくとも一種の酸化物であり、更に好ましくはY、La、Pr、Nd、Eu、Gd、Dy、Ho、Er、Ybから選ばれる少なくとも一種の酸化物であり、特に好ましくはY、La、Eu、Gd、Dy、Ho、Ybから選ばれる少なくとも一種の酸化物である。 In the second invention, the oxide of a rare earth element other than Ce may be at least one oxide selected from Sc, Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. Specifically, the oxide of a rare earth element other than Ce may be Sc2O3 , Y2O3 , La2O3 , Pr6O11 , Nd2O3 , Sm2O3 , Eu2O3 , Gd2O3 , Tb4O7 , Dy2O3 , Ho2O3 , Er2O3 , Tm2O3 , Yb2O3 , and Lu2O3 . In view of the excellent significance of the effect of the second invention due to the difficulty of conventional agglomeration inhibition, the oxide of the rare earth element is preferably at least one oxide selected from Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, more preferably at least one oxide selected from Y, La, Pr, Nd, Eu, Gd, Dy, Ho, Er and Yb, and particularly preferably at least one oxide selected from Y, La, Eu, Gd, Dy, Ho and Yb.
希土類元素の酸化物粉末では一次粒子が小さいほど粉砕され難くなり、活性面が減る。分散剤がない場合、活性面が少ないほど安定したスラリーとなる。しかし、一次粒子が小さすぎると凝集が強くなり、解砕できなくなる。解砕できたとしても強く凝集していた部分が解れた際に、その部分の活性が増え、安定しないスラリーとなる。この観点から一次粒子径は所定範囲である必要がある。具体的には、一次粒子は10nm以上100nm未満であり、12nm以上60nm以下が好ましく、15nm以上50nm以下が更に好ましく、特に好ましくは15nm以上35nm以下である。
第2発明において、希土類元素の酸化物粉末の一次粒子径は比表面積換算の一次粒子径であり、具体的には、BET1点法より測定された比表面積s(m2/g)から求めた粒径である。例えば、一次粒子径d(nm)はd=6000/(ρs)である。(ρは真密度(g/cm3))。
In rare earth oxide powder, the smaller the primary particles, the more difficult they are to pulverize, and the less active surface there is. In the absence of a dispersant, the less active surface there is, the more stable the slurry becomes. However, if the primary particles are too small, the particles will become strongly aggregated and will not be able to be disintegrated. Even if the particles can be disintegrated, when the strongly aggregated parts are disintegrated, the activity of those parts increases, resulting in an unstable slurry. From this perspective, the primary particle size must be within a certain range. Specifically, the primary particles are 10 nm or more and less than 100 nm, preferably 12 nm or more and 60 nm or less, more preferably 15 nm or more and 50 nm or less, and particularly preferably 15 nm or more and 35 nm or less.
In the second invention, the primary particle diameter of the rare earth oxide powder is the primary particle diameter calculated based on the specific surface area, specifically, the particle diameter calculated from the specific surface area s ( m2 /g) measured by the BET single point method. For example, the primary particle diameter d (nm) is d = 6000/(ρs) (ρ is the true density (g/ cm3 )).
更に、第2発明では、細孔直径0.005μm以上100μm以下の細孔容積(cm3/g)に真密度(g/cm3)を掛けて得られる数値が特定値である。
ここで、第2発明において、細孔容積ではなく、細孔容積に真密度を掛け合わせた値を規定する理由を以下説明する。
細孔容積(cm3/g)は測定するサンプルの重量当たり体積に依存する。従って体積当たりの細孔容積(cm3)が同じであっても、重量当たりの細孔容積(cm3/g)とすると、真密度が大きい化合物の値は小さくなる。
このため第2発明では、化合物種に依存しない細孔容積の値として、1gあたりの細孔容積(cm3/g)に真密度を掛け合わせた値を規定することとする。水銀ポロシメーターから求められる細孔容積(cm3/g)に真密度(1cm3あたりの質量)を掛けると、単位体積当たりの細孔容量になる。
Furthermore, in the second invention, the specific value is a numerical value obtained by multiplying the pore volume (cm 3 /g) of pores having a diameter of 0.005 μm or more and 100 μm or less by the true density (g/cm 3 ).
Here, the reason why the value obtained by multiplying the pore volume by the true density, rather than the pore volume, is specified in the second invention will be explained below.
The pore volume ( cm3 /g) depends on the volume per weight of the sample being measured. Therefore, even if the pore volume per volume ( cm3 ) is the same, the pore volume per weight ( cm3 /g) of a compound with a large true density will have a smaller value.
For this reason, in the second invention, the value of the pore volume independent of the compound type is defined as the value obtained by multiplying the pore volume per gram ( cm3 /g) by the true density. The pore volume ( cm3 /g) determined by a mercury porosimeter multiplied by the true density (mass per cm3 ) gives the pore volume per unit volume.
細孔直径0.005μm以上100μm以下の細孔容積に真密度を掛けた値(以下、「第一細孔容量」ともいう。)は、一次粒子間の空隙や凝集粒子間の間隙に由来する細孔容積全体を示しており、凝集の程度を示すパラメータである。単位当たりの細孔容積である第一細孔容量が少ないと凝集が強いことを示し、第一細孔容量が大きいと空隙が大きい又は多いことで凝集径が大きいことを示すため、第一細孔容量が適度であることは解砕しやすさにつながる。The value obtained by multiplying the pore volume of pores with diameters of 0.005 μm or more and 100 μm or less by the true density (hereinafter also referred to as the "first pore volume") indicates the total pore volume resulting from the gaps between primary particles and the gaps between aggregated particles, and is a parameter indicating the degree of aggregation. A small first pore volume, which is the pore volume per unit, indicates strong aggregation, while a large first pore volume indicates large or many voids, resulting in a large aggregate diameter, so an appropriate first pore volume leads to ease of disintegration.
具体的には、細孔直径0.005μm以上100μm以下の細孔容積に真密度を掛けた値である第一細孔容量は、3以上14以下である。第一細孔容量の値が低いと粒子間に空隙がない状態で凝集が強い。また、14超になると空隙が多くなり、初期の凝集径が大きくなる。また、空隙が多いことで衝撃を吸収し易くなることが予想され、ビーズミルでの解砕が難しくなる。これらの観点から、4以上12以下がより好ましく、5.5以上12以下が特に好ましい。Specifically, the first pore volume, which is the value obtained by multiplying the pore volume of pores with a diameter of 0.005 μm or more and 100 μm or less by the true density, is 3 or more and 14 or less. If the value of the first pore volume is low, there will be no gaps between the particles and the particles will be strongly aggregated. Furthermore, if the value exceeds 14, there will be many gaps and the initial aggregate diameter will be large. Furthermore, it is expected that the particles will be more likely to absorb impacts due to the large number of gaps, making it difficult to disintegrate them using a bead mill. From these viewpoints, 4 or more and 12 or less is more preferable, and 5.5 or more and 12 or less is particularly preferable.
また第2発明では、細孔直径5nm以上50nm以下の細孔容積(cm3/g)に真密度(g/cm3)を掛けて得られる数値(以下、「第二細孔容量」ともいう。)も特定値であることを特徴の一つとする。
細孔径において、粒子径の1/3~1/4程度の大きさの細孔径が粒子間に形成されることが知られている(特開平7―237982号公報参照)。細孔直径5nm以上50nm以下の細孔は約15nm以上200nm以下の凝集径の集合体の細孔に相当することになる。解砕による到達凝集径はビーズ径に依存するが、ビーズ径は後述する通り、解砕エネルギーとの兼ね合いで小さくしすぎることはできない。15nm以上200nm以下程度の凝集径の粒子が多く存在すると、ビーズ解砕の到達粒径と重複しやすい。ビーズ解砕の到達粒径に比較的近い凝集径の粒子は、ビーズ解砕の到達粒径より大きくても解砕しがたく、到達粒径よりも小さくてもそれらの凝集体が集合する力が強くなり、凝集体の凝集(3次凝集体)を形成しやすい。これらのことから、細孔直径5nm以上50nm以下の細孔容積が大きな粉末は、分散質の粒径が大きなスラリーとなりやすい。このことから第2発明では、細孔直径5nm以上50nm以下の細孔容積に真密度を掛け合わせた値である第二細孔容量は2.0以下であり、1.5以下が更に好ましく、1.2以下であることが特に好ましく、1.0以下であることが更に好ましく、0.8以下が更に一層好ましく、0.7以下であることが特に好ましい。また、第二細孔容量の下限値は0以上であれば特に限定されるものではないが、製造容易性の観点からは0.01以上が好ましく、0.02以上がより好ましく、0.05以上がさらに好ましい。
In addition, the second invention is characterized in that the numerical value (hereinafter also referred to as the "second pore volume") obtained by multiplying the pore volume ( cm3 /g) of pores with a pore diameter of 5 nm or more and 50 nm or less by the true density (g/ cm3 ) is also a specific value.
It is known that pores with a diameter of about 1/3 to 1/4 of the particle diameter are formed between particles (see JP-A-7-237982). Pores with a diameter of 5 nm to 50 nm correspond to pores of aggregates with an aggregate diameter of about 15 nm to 200 nm. The aggregate diameter achieved by crushing depends on the bead diameter, but the bead diameter cannot be made too small due to the balance with the crushing energy, as described later. If there are many particles with an aggregate diameter of about 15 nm to 200 nm, they tend to overlap with the particle diameter achieved by bead crushing. Particles with an aggregate diameter relatively close to the particle diameter achieved by bead crushing are difficult to crush even if they are larger than the particle diameter achieved by bead crushing, and even if they are smaller than the particle diameter achieved, the force of aggregation of the aggregates becomes strong, and they tend to form aggregates (tertiary aggregates). For these reasons, powders with a large pore volume with a pore diameter of 5 nm to 50 nm tend to become slurries with large particle diameters of dispersoids. For this reason, in the second invention, the second pore volume, which is the value obtained by multiplying the pore volume of pores with a diameter of 5 nm to 50 nm by the true density, is 2.0 or less, more preferably 1.5 or less, particularly preferably 1.2 or less, even more preferably 1.0 or less, even more preferably 0.8 or less, and particularly preferably 0.7 or less. The lower limit of the second pore volume is not particularly limited as long as it is 0 or more, but from the viewpoint of ease of production, it is preferably 0.01 or more, more preferably 0.02 or more, and even more preferably 0.05 or more.
また、第2発明の希土類元素の酸化物粉末の比表面積は、例えば、10m2/g以上160m2/g以下であることが上記一次粒子径を与えやすい点で好ましく、15m2/g以上110m2/g以下であることがより好ましく、20m2/g以上80m2/g以下が更に好ましい。 In addition, the specific surface area of the rare earth element oxide powder of the second invention is preferably, for example, 10 m2/g or more and 160 m2 /g or less in order to easily impart the above-mentioned primary particle diameter, more preferably 15 m2/g or more and 110 m2 /g or less, and even more preferably 20 m2/g or more and 80 m2 /g or less.
更に、希土類酸化物粉末の不純物量は少ない方がよい。合成時にNaイオン等が存在すれば、粒子成長を抑えられるが、Naは分解され難い。Naを好まない電子材料等があるため、Naイオンは少ない方がよい。この観点から、希土類酸化物粉末のNa含有量は100質量ppm以下が好ましく、特に好ましくは10質量ppm以下である。Na含有量は後述する実施例に記載の方法にて測定できる。 Furthermore, it is preferable that the amount of impurities in the rare earth oxide powder is small. If Na ions, etc. are present during synthesis, particle growth can be suppressed, but Na is difficult to decompose. Since there are electronic materials that do not like Na, it is preferable that there are few Na ions. From this perspective, the Na content of the rare earth oxide powder is preferably 100 mass ppm or less, and particularly preferably 10 mass ppm or less. The Na content can be measured by the method described in the examples below.
希土類酸化物粉末は結晶子径が所定範囲であることが好ましい。具体的には希土類酸化物粉末の結晶子径が、6nm以上25nm以下であることが好ましい。希土類酸化物粉末の結晶子径が所定以上であることで一次粒子径を一定以上としやすく、一次粒子の凝集力を低下できる。また、結晶子径が所定以下とすることで一次粒子径を所定以下としやすく、且つ粒子同士のネッキングを防止できる。これらの点を考慮し、希土類酸化物粉末の結晶子径は、8nm以上20nm以下がより好ましい。
結晶子径は後述する実施例に記載の方法にて測定できる。
The rare earth oxide powder preferably has a crystallite diameter in a predetermined range. Specifically, the rare earth oxide powder preferably has a crystallite diameter of 6 nm or more and 25 nm or less. By making the crystallite diameter of the rare earth oxide powder greater than a predetermined value, the primary particle diameter is easily made greater than a certain value, and the cohesive force of the primary particles can be reduced. Furthermore, by making the crystallite diameter less than a predetermined value, the primary particle diameter is easily made less than a predetermined value, and necking between particles can be prevented. In consideration of these points, the crystallite diameter of the rare earth oxide powder is more preferably 8 nm or more and 20 nm or less.
The crystallite size can be measured by the method described in the Examples below.
第2発明の希土類酸化物粉末は、これを湿式解砕することでスラリーとすることができる。
第2発明の希土類酸化物粉末は特定の解砕処理における凝集粒径が特定範囲であることが好ましい。具体的には、第2発明の希土類酸化物粉末は、エタノールと混合して希土類酸化物粉末を10質量%含有するエタノールスラリーとした後、(A)の操作を、平均粒子径が前回測定値より大きくなるまで繰り返し行ったときに、最小となる平均粒子径(Dm)が10nm以上150nm以下となることが好ましい。希土類酸化物粉末を10質量%含有するエタノールスラリーとする方法としては、40.5gの純度99質量%以上のエタノールと4.5gの希土類酸化物粉末とを混ぜてスラリーとする方法が挙げられる。凝集粒径を測定するスラリーに分散剤は用いない。分散剤としては、後述する各種の分散剤の例が挙げられる。
(A):直径0.1mmのジルコニア製ビーズを用いて、スラリーに10分間のビーズミル処理を行い、その後、動的光散乱法により平均粒子径を測定する。
(A)の操作は、具体的には下記(a)とする。
(a):直径0.1mmのジルコニア製ビーズで、スラリー:ビーズの質量比を45:240とし、ベッセルの有効容積80ccのビーズミルにおいて、周速4m/s以上6m/s以下の条件で10分間のビーズミル処理を行い、その後、動的光散乱法により平均粒子径を測定する。
(ただし、平均粒子径が前回測定値より大きくなった場合にその時点でビーズミル処理を終了し、20回(A)を繰り返して2回目から20回目までの各回において前回測定値より平均粒子径が大きくならない場合も、20回(A)を繰り返した時点で終了する)。
ただし、ここで最小となる平均粒子径(Dm)とは、前記ビーズミル処理時10分間の処理毎にサンプリングして測定した動的光散乱法による平均粒子径の最小値の意味である。なお、平均粒子径はnm単位で表示して小数点以下の数値がある場合には小数点第1位を四捨五入して整数表示したときの値にて大小を判断する。
The rare earth oxide powder of the second invention can be made into a slurry by wet crushing it.
The rare earth oxide powder of the second invention preferably has a specific range of aggregate particle size in a specific crushing treatment. Specifically, the rare earth oxide powder of the second invention is preferably mixed with ethanol to prepare an ethanol slurry containing 10% by mass of rare earth oxide powder, and then the operation (A) is repeated until the average particle size becomes larger than the previous measurement value, and the minimum average particle size (Dm) is preferably 10 nm or more and 150 nm or less. As a method for preparing an ethanol slurry containing 10% by mass of rare earth oxide powder, a method of mixing 40.5 g of ethanol having a purity of 99% by mass or more with 4.5 g of rare earth oxide powder to prepare a slurry can be mentioned. No dispersant is used in the slurry for measuring the aggregate particle size. Examples of dispersants include various dispersants described later.
(A): The slurry is subjected to a bead mill treatment for 10 minutes using zirconia beads having a diameter of 0.1 mm, and then the average particle size is measured by a dynamic light scattering method.
The operation (A) is specifically the following (a).
(a): Using zirconia beads having a diameter of 0.1 mm, the slurry:beads mass ratio was set to 45:240, and a bead mill treatment was carried out for 10 minutes in a bead mill having an effective volume of a vessel of 80 cc at a peripheral speed of 4 m/s to 6 m/s, and then the average particle diameter was measured by a dynamic light scattering method.
(However, if the average particle size becomes larger than the previous measurement value, the bead mill treatment is terminated at that point, and even if the average particle size does not become larger than the previous measurement value in each of the second to twentieth repetitions of (A) 20 times, the treatment is terminated when (A) has been repeated 20 times.)
Here, the minimum average particle size (Dm) means the minimum value of the average particle size measured by dynamic light scattering method by sampling every 10 minutes during the bead mill treatment. Note that the average particle size is expressed in nm units, and when there is a decimal value, the value is rounded off to the first decimal place to an integer, and the magnitude is judged based on the value.
上記のような測定により得られる最小の平均粒子径(Dm)とは、酸化物微粉末のスラリーに係る技術分野で一般的な解砕処理であるビーズ解砕処理による最小の凝集径を示している。最小の平均粒子径(Dm)は、150nm以下が好ましく、140nm以下がより好ましく、更に好ましくは105nm以下であり、特に好ましくは90nm以下である。当該最小の平均粒子径(Dm)を所定以下とすることで透明性を向上させることができるためである。更に最小の平均粒子径(Dm)は、10nm以上が好ましく、15nm以上がより好ましく、20nm以上が更に好ましく、50nm以上が最も好ましい。この下限を所定値以上とすることでスラリーの分散安定性を高めることができるためである。The minimum average particle diameter (Dm) obtained by the above measurement indicates the minimum agglomeration diameter by bead crushing treatment, which is a common crushing treatment in the technical field related to oxide fine powder slurries. The minimum average particle diameter (Dm) is preferably 150 nm or less, more preferably 140 nm or less, even more preferably 105 nm or less, and particularly preferably 90 nm or less. This is because the transparency can be improved by setting the minimum average particle diameter (Dm) to a predetermined value or less. Furthermore, the minimum average particle diameter (Dm) is preferably 10 nm or more, more preferably 15 nm or more, even more preferably 20 nm or more, and most preferably 50 nm or more. This is because the dispersion stability of the slurry can be improved by setting this lower limit to a predetermined value or more.
また、最小の平均粒子径(Dm)の測定時における多分散指数(PI)は、0.3以下であることが粒度分布がシャープであり、よりスラリーとしたときの高分散性、可視光透過性が維持されやすい点で好ましく、0.25以下であることがより好ましい。なお、多分散指数(PI)は、粒子径分布の広がりを示す無次元指標である。 In addition, the polydispersity index (PI) at the time of measuring the minimum average particle size (Dm) is preferably 0.3 or less, since this results in a sharp particle size distribution and makes it easier to maintain high dispersibility and visible light transmittance when made into a slurry, and is more preferably 0.25 or less. The polydispersity index (PI) is a dimensionless index that indicates the spread of the particle size distribution.
ベッセルの有効容積とは、ビーズ及びスラリーが収容される容器(ベッセル)の内容積を指す。また、ビーズミルの周速は周速4m/s以上6m/s以下のいずれの周速を採用してもよいが、より好ましくは周速4m/s以上5m/s以下であり、更に好ましくは周速4m/sである。The effective volume of the vessel refers to the internal volume of the container (vessel) in which the beads and slurry are contained. The peripheral speed of the bead mill may be any speed between 4 m/s and 6 m/s, but is more preferably between 4 m/s and 5 m/s, and even more preferably 4 m/s.
動的光散乱法(光子相関法)による平均粒子径及び多分散指数(PI)の測定には、動的光散乱光度計に測定試料を充填して行う。測定試料は、上記のスラリーの一部を取り出し、分散媒として湿式解砕時に用いた溶媒を用いて、超音波処理を施さない試料とする。測定試料の濃度は、1000~10000容量倍の範囲において、動的光散乱光度計が適正濃度と判定する希釈倍率とする。動的光散乱光度計としては、光子相関法で求めた自己相関関数よりキュムラント法解析で平均粒子径及び多分散指数(PI)を求める方法を採用する装置を採用でき、例えば、大塚電子製ELSZ-2000ZSを用いることができる。
なお、キュムラント法については、JIS Z 8828:2019「粒子径解析―動的光散乱法」の「9.2.1 キュムラント法」及び同JISの附属書Aの「A.1.2キュムラント法」に記載されている。
The measurement of the average particle size and polydispersity index (PI) by dynamic light scattering (photon correlation method) is performed by filling a measurement sample into a dynamic light scattering photometer. The measurement sample is a sample that is not subjected to ultrasonic treatment, with a part of the above-mentioned slurry taken out and the solvent used in wet disintegration as a dispersion medium. The concentration of the measurement sample is a dilution ratio in the range of 1000 to 10000 times by volume that the dynamic light scattering photometer judges to be an appropriate concentration. As the dynamic light scattering photometer, a device that employs a method of determining the average particle size and polydispersity index (PI) by cumulant analysis from the autocorrelation function obtained by the photon correlation method can be used, and for example, the ELSZ-2000ZS manufactured by Otsuka Electronics can be used.
The cumulant method is described in "9.2.1 Cumulant method" of JIS Z 8828:2019 "Particle size analysis - Dynamic light scattering method" and "A.1.2 Cumulant method" of Appendix A of the same JIS.
第2発明の希土類酸化物粉末を上記のように解砕して最小の平均粒子径(Dm)を求めて得られた解砕後のスラリーは、これを常温(15~25℃)で静置させたときに、下記式の計算値が所定範囲であることが好ましい。下記式は、7日間静置したときの粒径変動を示す。下記式の値は25%以下であることが好ましく、20%以下がより好ましく、15%以下であることがさらに好ましい。この上限以下であれば、超音波等をかけて容易に解砕直後と同等又はそれに近い粒径に戻すことができる。スラリーの平均粒子径は、微粒子の測定であるため、測定のバラつきも考える必要がある。実質粒径の変化がない場合、粒径が小さくなっているように測定されることもあるため、当該計算値は-15%以上であることが好ましく、-10%以上であることが更に好ましい。
下記式中、「解砕直後の平均粒子径(D0)」とは、上記の(A)の操作を、平均粒子径が前回測定値より大きくなるまで繰り返し行ったときに、20回目まで平均粒子径が前回測定値に比べて大きくならなかった場合、最小の平均粒子径(Dm)と同じ値となる。一方、20回目までの繰り返し中に、平均粒子径が前回測定値に比べて大きくなってビーズミル処理が終了した場合、その最後の測定値が「解砕直後の平均粒子径(D0)」となる。また下記式中、「解砕後7日後の平均粒子径(D7)」は、ビーズミル処理終了後のスラリーを上記条件にて7日間静置させたときに、再度上記の方法で測定した動的光散乱法(光子相関法)による平均粒子径をいう。式:(解砕後7日後の平均粒子径(D7)-解砕直後の平均粒子径(D0))/解砕直後(D0)の平均粒子径×100(%)
The rare earth oxide powder of the second invention is crushed as described above to obtain the minimum average particle size (Dm), and the resulting slurry is allowed to stand at room temperature (15 to 25°C), and the calculated value of the following formula is preferably within a predetermined range. The formula below indicates the particle size variation when allowed to stand for 7 days. The value of the formula below is preferably 25% or less, more preferably 20% or less, and even more preferably 15% or less. If it is below this upper limit, it is possible to easily restore the particle size to the same or close to that immediately after crushing by applying ultrasound or the like. Since the average particle size of the slurry is a measurement of fine particles, it is necessary to consider the variation in the measurement. If there is no substantial change in particle size, the particle size may be measured as if it is smaller, so the calculated value is preferably -15% or more, and even more preferably -10% or more.
In the following formula, "average particle size immediately after disintegration (D0)" is the same value as the minimum average particle size (Dm) when the above operation (A) is repeated until the average particle size becomes larger than the previous measurement value, and the average particle size does not become larger than the previous measurement value up to the 20th time. On the other hand, when the average particle size becomes larger than the previous measurement value during the 20th repetition and the bead mill treatment is terminated, the last measurement value becomes "average particle size immediately after disintegration (D0)". In addition, in the following formula, "average particle size 7 days after disintegration (D7)" refers to the average particle size measured again by the above method when the slurry after the bead mill treatment is left to stand for 7 days under the above conditions. Formula: (average particle size 7 days after disintegration (D7) - average particle size immediately after disintegration (D0)) / average particle size immediately after disintegration (D0) x 100 (%)
第2発明の希土類酸化物粉末は、解砕直後の平均粒子径(D0)は、210nm以下であることが好ましく、150nm以下であることが更に好ましく、120nm以下であることが特に好ましい。静置後の透過率を高めることができるためである。また、解砕直後の平均粒子径(D0)は、25nm以上であることが好ましく、50nm以上であることが更に好ましい。スラリーの分散性を高めることができるためである。The rare earth oxide powder of the second invention preferably has an average particle size (D0) immediately after crushing of 210 nm or less, more preferably 150 nm or less, and particularly preferably 120 nm or less. This is because the transmittance after standing can be increased. In addition, the average particle size (D0) immediately after crushing is preferably 25 nm or more, and more preferably 50 nm or more. This is because the dispersibility of the slurry can be increased.
第2発明の希土類酸化物粉末は、解砕7日後の平均粒子径(D7)が150nm以下であることが好ましく、120nm以下であることが更に好ましく、100nm以下であることが特に好ましい。静置後の透過率を高めることができるためである。また、解砕7日後の平均粒子径(D7)は、25nm以上であることが好ましく、50nm以上であることが更に好ましい。スラリーの分散性を高めることができるためである。The rare earth oxide powder of the second invention preferably has an average particle size (D7) of 150 nm or less after 7 days of crushing, more preferably 120 nm or less, and particularly preferably 100 nm or less. This is because the transmittance after standing can be increased. In addition, the average particle size (D7) of 25 nm or more after 7 days of crushing is preferably 25 nm or more, and more preferably 50 nm or more. This is because the dispersibility of the slurry can be increased.
第2発明の希土類酸化物粉末は、解砕7日後にスラリー20mlに対して、40Wの超音波(周波数40kHz)を5分照射した平均粒子径(D7S)が、150nm以下であることが好ましく、120nm以下であることが更に好ましく、100nm以下であることが特に好ましい。静置後の透過率を高めることができるためである。また、当該平均粒子径(D7S)は、25nm以上であることが好ましく、50nm以上であることが更に好ましい。スラリーの分散性を高めることができるためである。 The rare earth oxide powder of the second invention has an average particle size (D7S) of preferably 150 nm or less, more preferably 120 nm or less, and particularly preferably 100 nm or less, when 20 ml of the slurry is irradiated with 40 W ultrasound (frequency 40 kHz) for 5 minutes 7 days after crushing. This is because the transmittance after standing can be increased. Moreover, the average particle size (D7S) is preferably 25 nm or more, and more preferably 50 nm or more, because this is because the dispersibility of the slurry can be increased.
上述した比表面積(m2/g)、一次粒子径(nm)、第一細孔容量、第二細孔容量、Na含有量、Dm(nm)、D0(nm)、D7(nm)、(D7-D0/D0)(%)、D7S(nm)を得るためには、後述する好適な希土類酸化物粉末の製造方法を採用し、混合、洗浄又は焼成の条件を調整すればよい。 In order to obtain the above-mentioned specific surface area ( m2 /g), primary particle diameter (nm), first pore volume, second pore volume, Na content, Dm (nm), D0 (nm), D7 (nm), (D7-D0/D0) (%) and D7S (nm), it is sufficient to adopt a suitable manufacturing method for rare earth oxide powder described below and adjust the mixing, washing or firing conditions.
次いで第2発明の希土類酸化物粉末の好適な製造方法について説明する。
本製造方法は、炭酸塩水溶液(以下「A液」ともいう。)と希土類元素の水溶性塩水溶液(以下「B液」ともいう。)とを反応槽を同時に投入して、混合液のpHが6.5~7.0、好ましくは6.5~6.9となるように混合して炭酸塩と希土類元素の水溶性塩とを反応させ、A液とB液の混合開始から5分以内に固液分離を開始する反応・固液分離工程と、
反応・固液分離工程で得られた残渣をアルコール又は含水アルコールで洗浄する洗浄工程と、
洗浄した残渣を、焼成する焼成工程とを含むものである。
第2発明の希土類酸化物粉末を首尾よく得る点から、好適には、B液である希土類元素の水溶性塩水溶液における酸化物換算の水溶性塩濃度が10~400g/Lであり、より好適には20~300g/Lであり、特に好適には20~200g/Lであり、最も好ましくは20g/L以上100g/L未満である。
本製造方法は、第1発明の希土類酸化物粉末の製造方法と、A液とB液の混合液を必ずしも高速撹拌しなくてよい点、反応・固液分離工程で得られた残渣をアルコールだけでなく、含水アルコールでも洗浄してよい点、及び、B液における希土類元素の水溶性塩水溶液の好ましい濃度範囲が異なる。
Next, a preferred method for producing the rare earth oxide powder of the second invention will be described.
The present production method includes a reaction/solid-liquid separation step in which an aqueous carbonate solution (hereinafter also referred to as "liquid A") and an aqueous water-soluble salt solution of a rare earth element (hereinafter also referred to as "liquid B") are simultaneously charged into a reaction vessel, and mixed so that the pH of the mixed solution becomes 6.5 to 7.0, preferably 6.5 to 6.9, to react the carbonate with the water-soluble salt of the rare earth element, and solid-liquid separation is initiated within 5 minutes from the start of mixing of liquids A and B;
a washing step of washing the residue obtained in the reaction and solid-liquid separation step with alcohol or aqueous alcohol;
and a calcination step of calcining the washed residue.
In order to successfully obtain the rare earth oxide powder of the second invention, the water-soluble salt concentration in the water-soluble salt aqueous solution of the rare earth element, which is Liquid B, is preferably 10 to 400 g/L, more preferably 20 to 300 g/L, particularly preferably 20 to 200 g/L, and most preferably 20 g/L or more and less than 100 g/L.
This production method differs from the method for producing rare earth oxide powder of the first invention in that the mixed liquid of liquid A and liquid B does not necessarily need to be stirred at high speed, the residue obtained in the reaction and solid-liquid separation step may be washed not only with alcohol but also with hydrous alcohol, and the preferred concentration range of the water-soluble salt solution of the rare earth element in liquid B is different.
(反応・固液分離工程)
炭酸塩水溶液であるA液において、炭酸塩は、炭酸水素アンモニウム、炭酸アンモニウム、炭酸ナトリウム、炭酸水素ナトリウム等が挙げられる。本明細書でいう炭酸塩とは正塩だけでなく酸性塩である炭酸水素塩を含む。混合液のpHの調製が容易な点やナトリウム含量を低減する点から、炭酸水素アンモニウムが好ましい。
希土類元素の水溶性塩水溶液であるB液において、希土類元素の水溶性塩としては、硝酸塩、酢酸塩、アンミン錯体、塩化物が挙げられ、混合液のpHの調製が容易な点や生産性の観点から硝酸塩が好ましい。
(Reaction and solid-liquid separation process)
In the solution A which is an aqueous carbonate solution, examples of the carbonate include ammonium hydrogen carbonate, ammonium carbonate, sodium carbonate, sodium hydrogen carbonate, etc. In this specification, carbonate includes not only normal salts but also hydrogen carbonate which is an acidic salt. Ammonium hydrogen carbonate is preferred from the viewpoints of easy adjustment of the pH of the mixed solution and reduction of the sodium content.
In the solution B, which is an aqueous solution of a water-soluble salt of a rare earth element, examples of the water-soluble salt of the rare earth element include nitrates, acetates, ammine complexes, and chlorides. From the viewpoints of ease of adjusting the pH of the mixed solution and productivity, nitrates are preferred.
本製造方法を採用するに際して、A液及びB液の濃度は、所定範囲内であることも、一次粒子径、第一細孔容量、第二細孔容量を首尾よく所定範囲とする点から好ましい。具体的にはA液における炭酸塩の濃度は5~25質量%であることが好ましく、10~15質量%であることがより好ましい。B液における希土類元素の水溶性塩の濃度については、上記の通りである。When employing this manufacturing method, it is also preferable that the concentrations of Liquid A and Liquid B are within a predetermined range in order to successfully set the primary particle size, the first pore volume, and the second pore volume within the predetermined range. Specifically, the concentration of carbonate in Liquid A is preferably 5 to 25 mass%, and more preferably 10 to 15 mass%. The concentration of the water-soluble salt of the rare earth element in Liquid B is as described above.
本製造方法において、炭酸塩水溶液であるA液と希土類元素の水溶性塩水溶液であるB液とは両者の混合液のpHが6.5~7.0、好ましくは6.5~6.9となるように反応槽に同時に投入される。ここでいうpHは両者の混合液の温度でのpHである。混合液のpHが7.0超となると、一次粒子が大きなものとなってしまう。またpHを6.5以上とすることはA液中の希土類イオンがほぼ全て沈殿する利点がある。A液及びB液はいずれも投入時点で加温しないことが好ましい。A液及びB液は、反応槽への投入時点で5~50℃であることが好適であり、混合液の温度は5~40℃であることが好適である。一次粒子径を好適な範囲内とするために、反応を極短時間で行い、すぐに濾過することが好ましい。このために、混合液のpHが、A液及びB液の反応槽の投入開始時点(A液とB液との混合開始時点)から反応生成物が生じる時点(より具体的には固液分離開始時点)まで6.5~7.0、好ましくは6.5~6.9の範囲内であるように両液の投入のタイミング及び投入速度を調整して、pHを上記範囲に一定に維持することが好適である。pHが上記範囲となることで反応進行がスムーズに起こる。In this manufacturing method, liquid A, which is an aqueous carbonate solution, and liquid B, which is an aqueous solution of a water-soluble salt of a rare earth element, are simultaneously introduced into a reaction vessel so that the pH of the mixture of the two is 6.5 to 7.0, preferably 6.5 to 6.9. The pH here is the pH at the temperature of the mixture of the two. If the pH of the mixture exceeds 7.0, the primary particles will become large. In addition, setting the pH at 6.5 or higher has the advantage that almost all of the rare earth ions in liquid A will precipitate. It is preferable that neither liquid A nor liquid B is heated at the time of introduction. It is preferable that liquid A and liquid B are 5 to 50°C at the time of introduction into the reaction vessel, and the temperature of the mixture is 5 to 40°C. In order to keep the primary particle size within a suitable range, it is preferable to carry out the reaction in an extremely short time and filter it immediately. For this reason, it is preferable to adjust the timing and rate of introduction of both liquids so that the pH of the mixed liquid is within a range of 6.5 to 7.0, preferably 6.5 to 6.9, from the time when the introduction of liquid A and liquid B into the reaction vessel starts (the time when mixing of liquid A and liquid B starts) to the time when the reaction product is generated (more specifically, the time when solid-liquid separation starts), thereby maintaining the pH constant within the above range. The reaction proceeds smoothly when the pH is within the above range.
A液とB液とが同時に添加されるとは、反応槽においてA液が投入される時点と、B液が投入される時点とが少なくとも一部で同時となることを意味する。上述した通り、混合液のpHが、A液及びB液の反応槽の投入開始時点(A液とB液との混合開始時点)から反応生成物が生じる時点(より具体的には固液分離開始時点)まで混合液のpHが継続して6.5~7.0、好ましくは6.5~6.9の範囲内であるためには、上記の濃度のA液とB液とについて、それぞれの投入開始をほぼ同時とし、投入速度を一定とすることが好ましい。またA液とB液の投入速度は、A液とB液の混合開始から5分以内、より好適には3分以内に固液分離を開始できるように調整する。
本発明者は反応槽に予め入れておいたA液にB液を添加したり、反応槽に予め入れておいたB液にA液を投入するのではなく、所定濃度のA液とB液を同時投入し、且つ所定pHを維持した条件で混合することで、短時間で反応を済ませることができ、これを所定の後処理に供すると、一次粒子径が小さく分散性が良く透明性に優れたスラリーが得られる第2発明の希土類酸化物粉末を得ることができることを見出した。
The simultaneous addition of liquid A and liquid B means that the time when liquid A is added to the reaction vessel and the time when liquid B is added are at least partially simultaneous. As described above, in order for the pH of the mixed liquid to remain within the range of 6.5 to 7.0, preferably 6.5 to 6.9, from the time when liquid A and liquid B are added to the reaction vessel (the time when mixing of liquid A and liquid B is started) to the time when the reaction product is generated (more specifically, the time when solid-liquid separation is started), it is preferable that the introduction of liquid A and liquid B having the above concentrations is started almost simultaneously and the introduction speed is constant. The introduction speed of liquid A and liquid B is adjusted so that solid-liquid separation can be started within 5 minutes, more preferably within 3 minutes, from the start of mixing of liquid A and liquid B.
The present inventors have found that, rather than adding liquid B to liquid A that has already been placed in a reaction tank, or pouring liquid A into liquid B that has already been placed in a reaction tank, by simultaneously pouring liquid A and liquid B of predetermined concentrations and mixing them under conditions that maintain a predetermined pH, it is possible to complete the reaction in a short period of time, and by subjecting this to a predetermined post-treatment, it is possible to obtain the rare earth oxide powder of the second invention, which has a small primary particle size, good dispersibility, and provides a slurry with excellent transparency.
反応槽においてA液とB液の混合液は撹拌されることが、首尾よく第2発明の希土類酸化物粉末が得られる点で好ましく、高速撹拌であっても低速攪拌であっても中速攪拌であってもよい。
撹拌速度は100rpm以上25000rpm以下が好ましく、200rpm以上21000rpm以下がより好ましい。
低速攪拌としては100rpm以上1000rpm未満の撹拌が挙げられ、200rpm以上がより好ましい。
中速攪拌としては1000rpm以上10000rpm未満の撹拌が挙げられる。
高速撹拌としては10000rpm以上25000rpm以下の撹拌が挙げられる。高速撹拌の場合、18000rpm以上21000rpmが特に好ましい。
一次粒子径を特に好ましく小さくできる点から高速撹拌が好ましい。
反応槽としては、所定の回転数の撹拌が可能な撹拌装置(反応槽と一体型のものを含む)を備えるものであれば反応槽の容量は生産量等に応じて適宜定めればよい。ただし、高速撹拌装置を備える反応槽の容量は、高速撹拌装置の大きさの制限もあり、50mL~5Lが好適であり、100mL~2Lであることがより好適であり、100mL~1Lであることが更に好適である。
It is preferable to stir the mixture of liquids A and B in the reaction vessel in order to successfully obtain the rare earth oxide powder of the second invention. Stirring may be at high, low or medium speed.
The stirring speed is preferably from 100 rpm to 25,000 rpm, and more preferably from 200 rpm to 21,000 rpm.
Low speed stirring includes stirring at 100 rpm or more and less than 1000 rpm, and stirring at 200 rpm or more is more preferable.
Medium speed stirring includes stirring at 1,000 rpm or more and less than 10,000 rpm.
The high speed stirring may be from 10,000 rpm to 25,000 rpm. In the case of high speed stirring, stirring at 18,000 rpm to 21,000 rpm is particularly preferred.
High speed stirring is preferred since it is possible to preferably reduce the primary particle size.
The capacity of the reaction tank may be appropriately determined according to the production amount, etc., so long as the reaction tank is equipped with a stirring device (including one integrated with the reaction tank) capable of stirring at a predetermined rotation speed. However, the capacity of the reaction tank equipped with a high-speed stirring device is limited by the size of the high-speed stirring device, and is preferably 50 mL to 5 L, more preferably 100 mL to 2 L, and even more preferably 100 mL to 1 L.
(洗浄工程)
上記の固液分離工程で得られた残渣(「固形状物」ともいう。)は、アルコール又は含水アルコールで洗浄することも重要である。アルコールとしては、メタノール、エタノール、イソプロパノール等が挙げられるが、エタノールであることが、使用性の点から好ましい。含水アルコールを用いる場合、含水アルコールにおけるアルコール濃度は、10体積%以上が好ましく、50体積%以上がより好ましい。洗浄に用いるアルコールの量は、洗浄対象である固形状物の酸化物換算量1gに対して、0.1L~50Lであることが好ましく、0.5L~20Lであることがより好ましく、1L~10Lであることがさらに好ましい。ここでいう量は、アルコールを数回残渣に通液して洗浄する場合にはその総量である。
(Washing process)
It is also important to wash the residue (also referred to as "solid matter") obtained in the solid-liquid separation step with alcohol or hydrous alcohol. Examples of alcohol include methanol, ethanol, isopropanol, etc., but ethanol is preferred from the viewpoint of usability. When hydrous alcohol is used, the alcohol concentration in the hydrous alcohol is preferably 10% by volume or more, more preferably 50% by volume or more. The amount of alcohol used for washing is preferably 0.1 L to 50 L, more preferably 0.5 L to 20 L, and even more preferably 1 L to 10 L per 1 g of oxide equivalent of the solid matter to be washed. The amount referred to here is the total amount when the alcohol is passed through the residue several times to wash it.
(焼成工程)
焼成温度は、1000℃以下であることが、凝集抑制の点、及び結晶成長の抑制の点で好ましく、800℃以下であることがより好ましい。焼成温度は、500℃以上であることが、炭素含有量低減の点で好ましい。この観点から、焼成温度は500℃以上1000℃以下であることがより好適であり、500℃以上800℃以下が更に好適である。焼成は、大気雰囲気などの活性ガス雰囲気下、及びアルゴンや窒素などの不活性雰囲気下で行うことができるが、活性ガス雰囲気下、特に大気雰囲気下で行うことが好ましい。
(Firing process)
The firing temperature is preferably 1000° C. or less in terms of suppressing aggregation and suppressing crystal growth, and more preferably 800° C. or less. The firing temperature is preferably 500° C. or more in terms of reducing the carbon content. From this viewpoint, the firing temperature is more preferably 500° C. or more and 1000° C. or less, and even more preferably 500° C. or more and 800° C. or less. The firing can be performed under an active gas atmosphere such as air atmosphere, and an inert atmosphere such as argon or nitrogen, but is preferably performed under an active gas atmosphere, particularly air atmosphere.
(解砕工程)
焼成して得られた希土類酸化物粉末は粗粒を解砕することが好ましい。解砕には、乾式粉砕機を用いることができ、例えば、粉砕機(商品名:フォースミル、大阪ケミカル製)を用いることができる。
(Crushing process)
It is preferable to crush the coarse particles of the rare earth oxide powder obtained by firing. For crushing, a dry crusher can be used, for example, a crusher (product name: Force Mill, manufactured by Osaka Chemical Co., Ltd.).
次いで、上記のようにして得られた希土類酸化物粉末を湿式解砕してスラリーとするスラリーの製造方法について説明する。Next, we will explain the method for producing a slurry by wet-grinding the rare earth oxide powder obtained as described above.
湿式解砕は、ビーズミルにより行うことが、高分散が可能という面で好適である。ビーズミルのビーズは通常球状である。ビーズの材質は、ジルコニア、アルミナ、窒化ケイ素、炭化ケイ素、炭化タングステン、耐摩耗鋼やステンレス等を挙げることができ、ジルコニアが好適である。ここでいうジルコニアにはYSZやPSZ等の安定化ジルコニアを含む。Wet disintegration is preferably performed using a bead mill, as this allows for high dispersion. The beads in a bead mill are usually spherical. Bead materials include zirconia, alumina, silicon nitride, silicon carbide, tungsten carbide, wear-resistant steel, stainless steel, etc., with zirconia being preferred. Zirconia here includes stabilized zirconia such as YSZ and PSZ.
解砕時のビーズ径は0.01~0.3mmが好ましい。解砕による到達粒径はビーズ径に基づき、例えばビーズ径の1/1000程度となるため、ビーズ径は小さい方がよいが、小さすぎると解砕エネルギーが小さくなるため、凝集が解れないことがあり得る。この観点から、解砕時のビーズ径0.05~0.15mmがより好ましい。The bead diameter during crushing is preferably 0.01 to 0.3 mm. The particle size achieved by crushing is based on the bead diameter, for example, about 1/1000 of the bead diameter, so a smaller bead diameter is better, but if the bead diameter is too small, the crushing energy will be small and agglomerations may not break down. From this perspective, a bead diameter of 0.05 to 0.15 mm during crushing is more preferable.
希土類酸化物粉末を分散させる溶媒は、水よりも分散性が良好な点で、一価アルコールが好ましく、特に第一級アルコールが好ましく、とりわけエタノールが好ましい。一価アルコール溶媒としては、メタノール、エタノール、1-プロパノール、2-プロパノール、1-ブタノール、2-ブタノールが挙げられる。一価アルコールは実験室の洗浄材等で頻繁に使用されており、入手し易い。また、エタノール、1-プロパノールは有機溶剤中毒予防規則の対象外であるため、取り扱いやすい。なお、一価アルコールは純度が99容量%以上であることが好適である。 As a solvent for dispersing rare earth oxide powder, monohydric alcohol is preferable because it has better dispersibility than water, and primary alcohol is especially preferable, and ethanol is especially preferable. Examples of monohydric alcohol solvents include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, and 2-butanol. Monohydric alcohols are frequently used as cleaning materials in laboratories and are easy to obtain. In addition, ethanol and 1-propanol are not subject to the Organic Solvent Poisoning Prevention Regulations, so they are easy to handle. It is preferable that the purity of the monohydric alcohol is 99% by volume or more.
また、第2発明の製造方法で得られるスラリーにおける希土類酸化物粉末の割合は、1~50質量%であることが、所望の可視光透過率を得る点から好適であり、5~20質量%であることがより好ましい。In addition, the proportion of rare earth oxide powder in the slurry obtained by the manufacturing method of the second invention is preferably 1 to 50 mass% in order to obtain the desired visible light transmittance, and more preferably 5 to 20 mass%.
第2発明のスラリーの製造方法は、得られるスラリーの平均粒子径が、200nm以下まで解砕することが好ましく、10nm以上150nm以下となるまで解砕するものであることがより好ましく、15nm以上140nm以下が更に好ましく、特に好ましくは20nm以上105nm以下である。上記上限以下、特に上記範囲であることで、透過性や安定性に優れる。In the method for producing a slurry according to the second invention, the average particle size of the resulting slurry is preferably crushed to 200 nm or less, more preferably 10 nm to 150 nm, even more preferably 15 nm to 140 nm, and particularly preferably 20 nm to 105 nm. By being below the upper limit, particularly within the above range, the permeability and stability are excellent.
第2発明のスラリーの製造方法は、得られるスラリーの多分散指数(PI)が、0.3以下となることが好ましく、0.25以下となることが好ましい。多分散指数(PI)は低ければ低いほど好ましいが、製造容易性の点からは0.1以上であることが好ましい。In the method for producing a slurry according to the second invention, the polydispersity index (PI) of the resulting slurry is preferably 0.3 or less, and more preferably 0.25 or less. The lower the polydispersity index (PI), the better, but from the viewpoint of ease of production, it is preferable that the PI is 0.1 or more.
第2発明のスラリーの製造方法は、解砕後7日後に静置したスラリーの可視光透過率が40~95%となる方法であることが好ましく、50~80%となる方法であることがより好ましい。可視光透過率は後述する実施例に記載の方法にて測定できる。The method for producing the slurry of the second invention is preferably a method in which the visible light transmittance of the slurry left to stand for 7 days after disintegration is 40 to 95%, and more preferably 50 to 80%. The visible light transmittance can be measured by the method described in the examples below.
第2発明のスラリーの製造方法は、分散剤を用いないことが好ましい。分散剤としては、イオン系界面活性剤、非イオン系界面活性剤、pH調整剤、溶解性塩類が挙げられ、例えば、ポリオキシエチレンアルキルエーテル、 ポリオキシエチレン2級アルコールエーテル、ポリオキシエチレンアルキルフェニルエー テル、ポリオキシエチレン、ポリオキシプロピレンブロックコポリマー、ポリオキシエチ レンポリオキシプロピレンアルキルエーテルなどのエーテル型や、ポリオキシエチレング リセリン脂肪酸エステル、ポリオキシエチレンヒマシ油および硬化ヒマシ油、ポリオキシエチレンソルビタン脂肪酸エステルなどのエステルエーテル型などが挙げられる。またジグリセリンラウレート等のポリグリセリン脂肪酸エステルも挙げられる。更に、硝酸、塩酸、酢酸、塩化ナトリウム、塩化カリウム、塩化マグネシウム、塩化カルシウムも挙げられる。また特開2007-126349号公報に記載のβ-ジケトンも挙げることができる。それ以外でも、添加材を入れることで分散性が向上するものも分散材とする。分散剤を用いないとは、分散剤の量がスラリー中10000質量ppm以下であることを意味することが好ましく、1000質量ppm以下であることを意味することがより好ましく、100質量ppm以下であることを意味することが更に好ましく、10質量ppm以下を意味することが更に一層好ましく、用いないことが特に好ましい。 The method for producing a slurry of the second invention preferably does not use a dispersant. Examples of dispersants include ionic surfactants, nonionic surfactants, pH adjusters, and soluble salts. For example, ether-type dispersants such as polyoxyethylene alkyl ether, polyoxyethylene secondary alcohol ether, polyoxyethylene alkylphenyl ether, polyoxyethylene, polyoxypropylene block copolymer, and polyoxyethylene polyoxypropylene alkyl ether, and ester-ether-type dispersants such as polyoxyethylene glycerin fatty acid ester, polyoxyethylene castor oil and hardened castor oil, and polyoxyethylene sorbitan fatty acid ester are also included. Polyglycerin fatty acid esters such as diglycerin laurate are also included. In addition, nitric acid, hydrochloric acid, acetic acid, sodium chloride, potassium chloride, magnesium chloride, and calcium chloride are also included. β-diketones described in JP 2007-126349 A can also be mentioned. In addition, dispersants that improve dispersibility by adding additives are also included. By "no dispersant is used," it is preferable to mean that the amount of dispersant in the slurry is 10,000 ppm by mass or less, more preferably 1,000 ppm by mass or less, even more preferably 100 ppm by mass or less, even more preferably 10 ppm by mass or less, and it is particularly preferable that no dispersant is used.
<第1発明を説明する実施例及び比較例>
以下、実施例により第1発明を更に詳細に説明する。しかしながら本発明の範囲は、かかる実施例に制限されない。
<Examples and Comparative Examples Explaining the First Invention>
The first invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited to such examples.
(実施例a1)
炭酸水素アンモニウムが13.0質量%溶解している炭酸水素アンモニウム水溶液(25℃)10kgと酸化物換算で300g/Lの濃度である硝酸イットリウム水溶液(25℃)40Lを準備した。前記炭酸水素アンモニウム水溶液は後述する実施例a2~9にも使用し、前記硝酸イットリウム水溶液は後述する実施例a2~4にも使用した。硝酸イットリウム水溶液を100mL/minにて、炭酸水素アンモニウム水溶液を両液の混合液のpHが6.8になるような流量にて同一の反応層に同時に投入して混合した。投入時に容器内の混合液を20,000rpmで撹拌させた。容器からあふれ出た懸濁液を逐次的に20秒間濾過した後、両液の投入及び撹拌を止め、濾物である残渣を10Lのエタノールで通水洗浄した。この通水洗浄作業は5回繰り返した。2液の混合開始から濾過開始までに係る時間は60秒~120秒であった。洗浄後の残渣を大気雰囲気下600℃で焼成することで約10gのY2O3を得た。また、反応槽の内容積は100mlであった。得られたY2O3の収率は20秒間濾過したことから換算して約99%であった。
上記の作業を10回繰り返して、10回の作業で得られたY2O3サンプルを混合した。得られたY2O3を、フォースミル(大阪ケミカル社製)にて30秒間解砕し、微粉末を得た。
得られたY2O3微粉末について、下記方法にて比表面積(m2/g)、一次粒子径(nm)、凝集径、初期嵩密度(AD)及びタップ嵩密度(TD)、Zr含有量、炭素含有量を測定し、初期嵩密度(AD)及びタップ嵩密度(TD)からPAD、PTD及びPAD-PTDの値を算出したほか、塗膜性を評価した。結果を表1に示す。
(Example a1)
10 kg of an aqueous ammonium hydrogen carbonate solution (25°C) in which 13.0% by mass of ammonium hydrogen carbonate was dissolved, and 40 L of an aqueous yttrium nitrate solution (25°C) with a concentration of 300 g/L in terms of oxide were prepared. The aqueous ammonium hydrogen carbonate solution was also used in Examples a2 to a9 described later, and the aqueous yttrium nitrate solution was also used in Examples a2 to a4 described later. The aqueous yttrium nitrate solution was simultaneously charged into the same reaction layer at 100 mL/min and the aqueous ammonium hydrogen carbonate solution was simultaneously charged into the same reaction layer at a flow rate such that the pH of the mixture of the two solutions was 6.8, and mixed. When the two solutions were charged, the mixture in the container was stirred at 20,000 rpm. The suspension overflowing from the container was filtered for 20 seconds in sequence, and then the charging and stirring of the two solutions was stopped, and the residue, which was the filtrate, was washed with 10 L of ethanol. This washing operation was repeated five times. The time from the start of mixing the two solutions to the start of filtration was 60 to 120 seconds. The washed residue was calcined at 600° C. in an air atmosphere to obtain about 10 g of Y 2 O 3. The inner volume of the reaction vessel was 100 ml. The yield of the obtained Y 2 O 3 was about 99% based on the 20-second filtration.
The above procedure was repeated 10 times, and the Y2O3 samples obtained in the 10 procedures were mixed. The obtained Y2O3 was crushed for 30 seconds in a force mill (manufactured by Osaka Chemical Co., Ltd.) to obtain a fine powder .
For the obtained Y2O3 fine powder, the specific surface area ( m2 /g), primary particle size (nm), agglomeration size, initial bulk density (AD), tapped bulk density (TD), Zr content, and carbon content were measured by the following methods, and the values of PAD , PTD, and PAD - PTD were calculated from the initial bulk density (AD) and tapped bulk density (TD), and the coating properties were also evaluated. The results are shown in Table 1.
(比表面積の測定方法)
マウンテック社製全自動比表面積計Macsorb model―1201を用いてBET1点法にて測定した。使用ガスは、窒素ヘリウム混合ガス(窒素30vol%)とした。測定の前処理としてガラスセルに粉末を入れ装置にセットし、セットしたガラスセルに窒素ガスを流通させて300℃で60分間脱気させた。
(Method of measuring specific surface area)
The measurement was performed by the BET one-point method using a Mountec fully automatic specific surface area meter Macsorb model-1201. The gas used was a nitrogen-helium mixed gas (nitrogen 30 vol%). As a pretreatment for the measurement, the powder was placed in a glass cell and set in the device, and nitrogen gas was passed through the set glass cell to degas it at 300°C for 60 minutes.
(一次粒子径の算出方法)
BET1点法より測定された比表面積s(m2/g)から求めた粒径を次式にて求めた。一次粒子径d(nm)はd=6000/(ρs)(ρは真密度(g/cm3))。真密度については、Y2O3が5.03(g/cm3)、Nd2O3が7.33(g/cm3)、Gd2O3が7.62(g/cm3)、Eu2O3が7.4(g/cm3)、Dy2O3が7.81(g/cm3)、Yb2O3が9.22(g/cm3)、とした。
(Calculation method of primary particle size)
The particle size was calculated from the specific surface area s ( m2 /g) measured by the BET single point method using the following formula: Primary particle diameter d (nm) was d = 6000/(ρs) (ρ is true density (g/ cm3 )). The true densities were 5.03 (g/ cm3 ) for Y2O3 , 7.33 (g/ cm3 ) for Nd2O3 , 7.62 (g/ cm3 ) for Gd2O3 , 7.4 (g/ cm3 ) for Eu2O3 , 7.81 (g/ cm3 ) for Dy2O3 , and 9.22 (g/ cm3 ) for Yb2O3 .
(凝集径(D100、D50、D90))
日機装株式会社製マイクロトラックMT3300EXIIにて測定した。測定の際には、ヘキサタリン酸ナトリウム0.2質量%溶解させた水溶液を充填している試料循環器のチャンバーに粉末の状態の試料を添加して、装置に備え付けの超音波照射装置にて40Wの超音波、周波数40kHzにて5分間分散させ、適正濃度であると装置が判定してからD100、D50、D90を測定した。
(Agglomeration diameter ( D100 , D50 , D90 ))
Measurements were performed using a Microtrac MT3300EXII manufactured by Nikkiso Co., Ltd. During the measurements, a powdered sample was added to a chamber of a sample circulator filled with an aqueous solution containing 0.2% by mass of sodium hexataphosphate dissolved therein, and dispersed for 5 minutes using an ultrasonic irradiation device equipped in the device at 40 W and a frequency of 40 kHz. After the device determined that the concentration was appropriate, D100 , D50 , and D90 were measured.
(初期嵩密度及びタップ嵩密度の測定方法)
1.試料の前処理:希土類酸化物粉末(実施例a1ではY2O3微粉末)は測定する直前に大阪ケミカル株式会社フォースミルで30秒間解砕を実施した。
2.測定
(1)内径10mm、外径12mm、高さ51mm、内面高さ50mm(内容積3.93cm3)のSUS304製の測定容器の質量(WC(g))を測定した。
(2)測定容器に目開き2mmのふるいを通して前処理後の試料をあふれるまで入れた。
(3)測定容器の上端面から盛り上がった粉末を、すり切り板を使ってすり切った。
(4)測定容器ごと質量(W0(g))を測定し、測定容器の質量(Wc(g))を差し引いて試料の質量(WA(g))を計算した。
(5)試料の入った測定容器の上に補助円筒(内径 下部12mm、上部10mm、外径14mm、高さ50mm(下部10mm、上部40mm)のSUS304製)を継ぎ足し、目開き2mmのふるいを通してさらに試料を充てんした。
(6)補助円筒を付けたまま試料の入った測定容器をタップ高さ10mm程度にて手振りにて容器をゴム板を敷いた机に打ち付けて600回タップを行った。その間、試料の高さが測定容器の上端面から常に20~30mm高くなるように試料を追加した。
(7)補助円筒を外して、測定容器の上にあふれている試料をすり切り板ですり切った。
(8)試料をすり切り後、測定容器ごと質量(W1(g))を測定し、測定容器の質量(Wc(g))を差し引いて試料の質量(WT1(g))を求めた。
(9)再度測定容器に補助円筒を取り付け、さらに目開き2mmのふるいを通して更に試料を充てんし、タップ高さ10mm程度にて手振りにて100回タップを行った。
(10)補助円筒を外して、測定容器の上にあふれている試料をすり切り板ですり切った。
(11)試料をすり切り後、測定容器ごと質量(W2(g))を測定し、測定容器の質量(Wc(g))を差し引いて試料の質量(WT2(g))を計算した。この値(WT2(g))と先の値(WT1(g))との差がWT1に対して0.3%以内であることを確かめた。0.3%を超えた場合は、前回との差が0.3%以内になるまで、(9)以降の操作を繰り返した。
(12)初期嵩密度及びタップ嵩密度を下記の式により計算した。
初期嵩密度(g/cm3)=WA(g)/3.93(cm3)
タップ嵩密度(g/cm3)=WT2(g)/3.93(cm3)
(13)以上の測定を3回行った。初期嵩密度及びタップ嵩密度は3回の平均値を採用した。
(Method of measuring initial bulk density and tapped bulk density)
1. Pretreatment of the sample: The rare earth oxide powder (Y 2 O 3 fine powder in Example a1) was crushed for 30 seconds in a force mill manufactured by Osaka Chemical Co., Ltd. immediately before the measurement.
2. Measurement (1) The mass (W c (g)) of a measurement vessel made of SUS304 having an inner diameter of 10 mm, an outer diameter of 12 mm, a height of 51 mm and an inner surface height of 50 mm (internal volume 3.93 cm 3 ) was measured.
(2) The pretreated sample was passed through a sieve with 2 mm openings and poured into a measurement container until it overflowed.
(3) The powder piled up on the top surface of the measuring container was leveled off using a leveling plate.
(4) The mass (W 0 (g)) of the measurement container was measured, and the mass (W c (g)) of the measurement container was subtracted from this to calculate the mass (W A (g)) of the sample.
(5) An auxiliary cylinder (made of SUS304, inner diameter: lower 12 mm, upper 10 mm, outer diameter 14 mm, height 50 mm (lower 10 mm, upper 40 mm)) was added on top of the measurement container containing the sample, and the sample was further filled in through a sieve with 2 mm openings.
(6) With the auxiliary cylinder still attached, the measurement container containing the sample was tapped 600 times by manually hitting the container against a rubber-covered desk at a tapping height of about 10 mm. During this time, sample was added so that the sample height was always 20 to 30 mm higher than the top surface of the measurement container.
(7) The auxiliary cylinder was removed, and the sample overflowing from the top of the measurement container was scraped off with a scraping plate.
(8) After the sample was leveled off, the mass (W 1 (g)) of the measurement container was measured, and the mass (W c (g)) of the measurement container was subtracted to determine the mass of the sample (W T1 (g)).
(9) The auxiliary cylinder was attached to the measurement container again, and the sample was further filled in through a sieve with 2 mm openings, and tapped 100 times by hand at a tapping height of about 10 mm.
(10) The auxiliary cylinder was removed, and the sample overflowing from the top of the measurement container was scraped off with a scraping plate.
(11) After the sample had been leveled off, the mass ( W2 (g)) of the measurement container was measured, and the mass ( Wc (g)) of the measurement container was subtracted to calculate the mass of the sample ( WT2 (g)). It was confirmed that the difference between this value ( WT2 (g)) and the previous value ( WT1 (g)) was within 0.3% of WT1 . If it exceeded 0.3%, the steps from (9) onwards were repeated until the difference from the previous value was within 0.3%.
(12) The initial bulk density and tapped bulk density were calculated according to the following formula.
Initial bulk density (g/cm 3 )=W A (g)/3.93 (cm 3 )
Tapped bulk density (g/cm 3 )=W T2 (g)/3.93 (cm 3 )
(13) The above measurements were carried out three times. The initial bulk density and the tapped bulk density were calculated by averaging the three measurements.
(空隙率)
測定された初期嵩密度及びタップ嵩密度をρ0とすると空隙率P(%)はP=(1-ρ0/ρ)×100から求めた。(ρは真密度(g/cm3))。
(Porosity)
When the measured initial bulk density and tapped bulk density were taken as ρ 0 , the porosity P (%) was calculated from P = (1 - ρ 0 /ρ) x 100 (ρ is the true density (g/cm 3 )).
(炭素含有量)
株式会社堀場製作所製炭素硫黄分析装置EMIA-320Vを用いて酸素気流中燃焼赤外線吸収法にて測定した。
(Carbon Content)
The measurement was performed by an infrared absorption method using a carbon/sulfur analyzer EMIA-320V manufactured by Horiba Ltd., in which the carbon and sulfur content was measured in an oxygen stream.
(Zr含有量)
株式会社日立ハイテクサイエンス社製ICP発光分光分析装置SPS-3520V-DDを用いて測定した。
(Zr content)
The measurement was carried out using an ICP optical emission spectrometer SPS-3520V-DD manufactured by Hitachi High-Tech Science Corporation.
(塗膜性の評価)
得られたY2O3微粉末3gとエタノールとを用いて、Y2O3濃度が30質量%のエタノールスラリーを調製し、40Wの超音波(周波数40kHz)で5分間分散した後、ギャップが10μmのアプリケーター(BEVS Industrial社製)を用いてPETフィルム上に塗膜した。塗膜性は以下の評価基準にて評価した。
A:塗工可能。
B:塗工できていない部分が発生する。
C:ギャップから分散質が出てこないため塗工不可。
(Evaluation of coating properties)
Using 3 g of the obtained Y2O3 fine powder and ethanol, an ethanol slurry with a Y2O3 concentration of 30 mass% was prepared, which was dispersed for 5 minutes with 40 W ultrasonic waves (frequency 40 kHz), and then coated on a PET film using an applicator with a gap of 10 μm (manufactured by BEVS Industrial Co., Ltd.). The coating properties were evaluated according to the following criteria.
A: Coating is possible.
B: There are areas where the coating is not completed.
C: Coating is not possible because no dispersed material comes out of the gap.
(実施例a2)
800℃で焼成した以外は実施例a1に記載の内容と同じとした。
(Example a2)
The same procedure was followed as in Example a1, except that the firing temperature was 800°C.
(実施例a3)
900℃で焼成した以外は実施例a1に記載の内容と同じとした。
(Example a3)
The procedure was the same as in Example a1, except that the firing temperature was 900°C.
(実施例a4)
500℃で焼成した以外は実施例a1に記載の内容と同じとした。
(Example a4)
The procedure was the same as in Example a1, except that the firing temperature was 500°C.
(実施例a5)
実施例1に記載の内容で、硝酸イットリウム水溶液ではなく、酸化物換算濃度が400g/Lである硝酸ネオジム水溶液を用いた。また焼成温度は900℃とした。これらの点以外は実施例a1と同じとした。
(Example a5)
The contents were the same as those of Example a1, except that an aqueous neodymium nitrate solution with an oxide equivalent concentration of 400 g/L was used instead of an aqueous yttrium nitrate solution. The firing temperature was 900° C. Other than these points, the composition was the same as Example a1.
(実施例a6)
実施例1に記載の内容で、硝酸イットリウム水溶液ではなく、酸化物換算濃度が250g/Lである硝酸ガドリニウム水溶液を用いた。また焼成温度は650℃とした。これらの点以外は実施例a1と同じとした。
(Example a6)
The contents were the same as those of Example a1, except that an aqueous gadolinium nitrate solution with an oxide equivalent concentration of 250 g/L was used instead of an aqueous yttrium nitrate solution. The firing temperature was 650° C. Other than these points, the same procedure was followed as in Example a1.
(実施例a7)
実施例1に記載の内容で、硝酸イットリウム水溶液ではなく、酸化物換算濃度が300g/Lである硝酸ユウロピウム水溶液を用いた。また焼成温度は650℃とした。これらの点以外は実施例a1と同じとした。
(Example a7)
The contents were the same as in Example 1, except that an aqueous europium nitrate solution with an oxide equivalent concentration of 300 g/L was used instead of an aqueous yttrium nitrate solution, and the firing temperature was 650° C. Other than these points, the same procedure was followed as in Example a1.
(実施例a8)
実施例1に記載の内容で、硝酸イットリウム水溶液ではなく、酸化物換算濃度が300g/Lである硝酸ジスプロシウム水溶液を用いた。また焼成温度は600℃とした。これらの点以外は実施例a1と同じとした。
(Example a8)
The contents were the same as those of Example a1, except that an aqueous solution of dysprosium nitrate having an oxide equivalent concentration of 300 g/L was used instead of an aqueous solution of yttrium nitrate. The firing temperature was set to 600° C. Other than these points, the composition was the same as that of Example a1.
(実施例a9)
実施例a1に記載の内容で、硝酸イットリウム水溶液ではなく、酸化物換算濃度が300g/Lである硝酸イッテルビウム水溶液を用いた。また焼成温度は600℃とした。これらの点以外は実施例a1と同じとした。
(Example a9)
The content of Example a1 was the same as that of Example a1, except that an aqueous ytterbium nitrate solution with an oxide equivalent concentration of 300 g/L was used instead of an aqueous yttrium nitrate solution. The firing temperature was set to 600° C. Other than these points, the composition was the same as that of Example a1.
(比較例a1)
本比較例は、特開2014-218384号公報の実施例1に相当する例である。
1.0mol/Lの硝酸イットリウム水溶液100mLにオレイン酸ナトリウム5gを添加し、2時間攪拌した。次いで、該水溶液にシクロヘキサン1000mLと非イオン系界面活性剤Span80(ソルビタンモノオレエート、関東化学(株)製)1.0gを加えて激しく(10,000rpmで)攪拌すると、微小な液滴からなるW/O型エマルション溶液が得られた。次に、炭酸水素アンモニウム13gを純水50mLに溶かして水溶液とし、エマルション溶液を激しく攪拌しながらこの炭酸水素アンモニウム水溶液を滴下した。炭酸水素アンモニウム水溶液の滴下に伴い白色の沈殿が生じた。滴下完了後、攪拌を続けながら室温(25℃)で1時間の熟成を行なった。その後、生じた沈殿をブフナー漏斗で水溶液からろ別し、得られた沈殿を75℃のオーブンで12時間乾燥させた後、アルミナ坩堝に入れ800℃大気雰囲気下で焼成した。こうして、8gの酸化イットリウム微粉末が得られた。その後、実施例a1に記載の方法で塗膜した。
この粉末を走査型電子顕微鏡(SEM)で観察したところ、粒径がおよそ100nmの凝集のない粒径の揃った球状の粒子群であった。比表面積から求める一次粒子径も100nm以上であった。
(Comparative Example a1)
This comparative example corresponds to Example 1 of JP 2014-218384 A.
5 g of sodium oleate was added to 100 mL of a 1.0 mol/L aqueous solution of yttrium nitrate, and the mixture was stirred for 2 hours. Next, 1000 mL of cyclohexane and 1.0 g of a nonionic surfactant Span 80 (sorbitan monooleate, manufactured by Kanto Chemical Co., Ltd.) were added to the aqueous solution, and the mixture was stirred vigorously (at 10,000 rpm), resulting in a W/O type emulsion solution consisting of minute droplets. Next, 13 g of ammonium hydrogen carbonate was dissolved in 50 mL of pure water to prepare an aqueous solution, and the aqueous solution of ammonium hydrogen carbonate was dropped into the emulsion solution while vigorously stirring it. A white precipitate was generated as the aqueous solution of ammonium hydrogen carbonate was dropped. After the dropwise addition was completed, the mixture was aged for 1 hour at room temperature (25°C) while continuing to stir. The precipitate was then filtered out of the aqueous solution using a Buchner funnel, and the resulting precipitate was dried in an oven at 75°C for 12 hours, then placed in an alumina crucible and fired in an air atmosphere at 800°C. Thus, 8 g of yttrium oxide fine powder was obtained. Thereafter, coating was performed as described in Example a1.
Observation of this powder with a scanning electron microscope (SEM) revealed that it was a group of spherical particles with a uniform particle size of about 100 nm without agglomeration. The primary particle size calculated from the specific surface area was also 100 nm or more.
(比較例a2)
本比較例は、特開2014-218384号公報の実施例1の焼成温度を変更したものに相当する例である。
焼成温度を600℃にした以外は比較例1と同じで作製した。この粉末を走査型電子顕微鏡(SEM)で観察したところ、SEM径がおよそ100nmと10nmの粒子が混在しており、低温焼成ではSEM径が均一な粒子を得られなかった。比表面積から求める一次粒子径も100nm以上であった。
(Comparative Example a2)
This comparative example corresponds to Example 1 of JP 2014-218384 A, except that the firing temperature was changed.
The powder was prepared in the same manner as in Comparative Example 1, except that the firing temperature was set to 600° C. When the powder was observed with a scanning electron microscope (SEM), particles with SEM diameters of approximately 100 nm and 10 nm were mixed, and particles with uniform SEM diameters could not be obtained by low-temperature firing. The primary particle diameter calculated from the specific surface area was also 100 nm or more.
(比較例a3)
本比較例は、J Nanopart Res (2013) 15:1438に相当する例である。
イットリウム元素として50mmol/L塩化イットリウム水溶液(pH=5.0)2Lを50mmol/LのNa2CO3水溶液2Lに瞬時に入れた。得られた懸濁液を直ぐに濾過して濾物をエタノール10Lで洗浄した後、600℃で焼成することで5gのY2O3を得た。その後、実施例1aに記載の方法で塗膜した。
(Comparative Example a3)
This comparative example corresponds to J Nanopart Res (2013) 15:1438.
2 L of 50 mmol/L yttrium chloride aqueous solution (pH = 5.0) was instantly added to 2 L of 50 mmol/L Na2CO3 aqueous solution. The resulting suspension was immediately filtered , and the residue was washed with 10 L of ethanol and then calcined at 600°C to obtain 5 g of Y2O3 . Then, a coating was performed by the method described in Example 1a.
(比較例a4)
本比較例は、特開平4-310516号公報に相当する例である。
18.0gのY2O3を900mLの希釈塩酸に溶解し、この溶液を40℃、9Lの希釈アンモニア水(アンモニア0.2モル含有)中に滴下した。30分かけて滴下し、滴下終了後、30分間熟成させた後、炭酸水素アンモニウム144gを900mLの水に溶かした水溶液を加えてイットリウム炭酸塩を析出させた。2時間熟成後濾過、水洗したのち得られたイットリウム炭酸塩にオクタノール900mLを加えて100℃で3時間攪拌しながら水分を蒸発させた。その後、濾過してイットリウム炭酸塩を取り出し、13.3Pa(0.1トル)160℃で減圧乾燥した。その後650℃で2時間焼成することで10gのY2O3が得られた。このY2O3の結晶子径は80Åであった。
(Comparative Example a4)
This comparative example corresponds to the example disclosed in Japanese Patent Application Laid-Open No. 4-310516.
18.0g of Y2O3 was dissolved in 900mL of diluted hydrochloric acid, and this solution was dropped into 9L of diluted ammonia water (containing 0.2 moles of ammonia) at 40°C. The solution was dropped over 30 minutes, and after the drop was completed, it was aged for 30 minutes, and then an aqueous solution of 144g of ammonium hydrogen carbonate dissolved in 900mL of water was added to precipitate yttrium carbonate. After aging for 2 hours, it was filtered and washed with water, and 900mL of octanol was added to the obtained yttrium carbonate, and the water was evaporated while stirring at 100°C for 3 hours. Then, the yttrium carbonate was taken out by filtration, and dried under reduced pressure at 13.3 Pa (0.1 torr) and 160°C. Then, it was calcined at 650°C for 2 hours to obtain 10g of Y2O3 . The crystallite diameter of this Y2O3 was 80 Å.
上記表1の通り、Ce以外の少なくとも1種の希土類元素の酸化物の粉末であって、所定の一次粒子径10nm以上60nm以下を有し、40Wの超音波分散処理して測定したD100が1μm以上10μm以下である、ないし、空隙率の差(PAD-PTD)が2.0%以上5.0%以下である各実施例の粉末は、塗膜性が良好であった。
一方、一次粒子径が10nm以上60nm以下の範囲外であるか、或いは、(PAD-PTD)が2.0%以上5.0%以下の範囲外である比較例a1~a4では40Wの超音波処理後の凝集径はいずれも大きくなり、塗膜性が得られないことが示された。
以上より、本発明の構成により、Ce以外の希土類酸化物において、一次粒子径(SSA換算径)数十nmでも容易に解砕でき、塗膜の形成が可能な希土類酸化物粉末を提供できることが判る。
As shown in Table 1 above, the powders of each example, which are oxides of at least one rare earth element other than Ce, have a predetermined primary particle size of 10 nm or more and 60 nm or less, have a D100 measured after ultrasonic dispersion treatment at 40 W of 1 μm or more and 10 μm or less, and have a porosity difference (P AD - P TD ) of 2.0% or more and 5.0% or less, had good film-forming properties.
On the other hand, in Comparative Examples a1 to a4 in which the primary particle size was outside the range of 10 nm or more and 60 nm or (P AD - P TD ) was outside the range of 2.0% or more and 5.0% or less, the aggregate size after ultrasonic treatment at 40 W was large, indicating that no coating properties were obtained.
From the above, it is clear that the configuration of the present invention can easily disintegrate rare earth oxides other than Ce even if the primary particle diameter (SSA equivalent diameter) is several tens of nm, and can provide rare earth oxide powder that can be used to form a coating film.
以下、実施例により第2発明を更に詳細に説明する。しかしながら本発明の範囲は、かかる実施例に制限されない。なお、下記実施例において、反応槽の内容積は低速攪拌では2L、高速攪拌では100mLであった。The second invention will be described in more detail below with reference to examples. However, the scope of the present invention is not limited to such examples. In the following examples, the internal volume of the reaction vessel was 2 L with low-speed stirring and 100 mL with high-speed stirring.
(実施例b1)
炭酸水素アンモニウムが13.0質量%溶解している炭酸水素アンモニウム水溶液(25℃)10kgと酸化物換算で50g/Lである硝酸イットリウム水溶液(25℃)40Lを準備した。前記炭酸水素アンモニウム水溶液は後述する実施例b2~6にも使用し、前記硝酸イットリウム水溶液は後述する実施例b2~b4及びb6にも使用した。硝酸イットリウム水溶液を600mL/minにて、炭酸水素アンモニウム水溶液を両液の混合液のpHが6.8(混合液の温度:20~30℃)になるような流量にて同一の容器に同時に投入して混合した。投入時に容器内の混合液を20,000rpmで高速攪拌させた。容器からあふれ出た懸濁液を逐次的に20秒間濾過した後、両液の投入及び撹拌を止め、濾物である残渣を10Lのエタノールで洗浄した。この洗浄作業は5回繰り返した。洗浄した濾過粉末を、大気雰囲気下700℃で焼成して10gのY2O3を得た。得られたY2O3を、フォースミル(大阪ケミカル社製社製)にて30秒間解砕し、微粉末を得た。得られたY2O3微粉末について、下記方法にて比表面積(m2/g)、一次粒子径(nm)、細孔直径0.005μm以上100μm以下の細孔容量*真密度、5nm以上50nm以下の細孔容積*真密度、Na含有量(質量ppm)、結晶子径(nm)を測定したほか、下記の解砕評価を行った。結果を表2に示す。
(Example b1)
10 kg of an aqueous solution of ammonium hydrogen carbonate (25°C) in which 13.0% by mass of ammonium hydrogen carbonate was dissolved, and 40 L of an aqueous solution of yttrium nitrate (25°C) in which the oxide equivalent was 50 g/L were prepared. The aqueous solution of ammonium hydrogen carbonate was also used in Examples b2 to b6 described later, and the aqueous solution of yttrium nitrate was also used in Examples b2 to b4 and b6 described later. The aqueous solution of yttrium nitrate was simultaneously charged into the same container at 600 mL/min and the aqueous solution of ammonium hydrogen carbonate was simultaneously charged into the same container at a flow rate such that the pH of the mixture of both solutions was 6.8 (temperature of the mixture: 20 to 30°C) and mixed. When the two solutions were charged, the mixture in the container was stirred at high speed at 20,000 rpm. The suspension overflowing from the container was filtered for 20 seconds in sequence, and then the charging and stirring of both solutions was stopped, and the residue, which was the filtrate, was washed with 10 L of ethanol. This washing operation was repeated five times. The washed filtered powder was calcined at 700°C in an air atmosphere to obtain 10 g of Y 2 O 3 . The obtained Y2O3 was crushed for 30 seconds in a force mill (manufactured by Osaka Chemical Co. , Ltd.) to obtain a fine powder. The obtained Y2O3 fine powder was measured for specific surface area ( m2 /g), primary particle size (nm), pore volume*true density of pore diameter 0.005μm to 100μm, pore volume*true density of pore diameter 5nm to 50nm, Na content (mass ppm), and crystallite size (nm) by the following method, and also the following crushing evaluation was performed. The results are shown in Table 2.
(比表面積(m2/g))
上記第1発明の実施例と同様の方法で測定した。
(Specific surface area ( m2 /g))
The measurement was carried out in the same manner as in the first embodiment of the present invention.
(一次粒子径の算出方法)
上記第1発明の実施例と同様の方法で算出した。
(Calculation method of primary particle size)
The calculation was carried out in the same manner as in the first embodiment of the present invention.
(細孔直径0.005μm~100μmの細孔容積*真密度及び5nm~50nmの細孔容積*真密度)
マイクロメリティクス社製オートポアIVを用いて細孔容積を測定した。
細孔直径が0.005μm以上100μm以下である範囲の累積容積を細孔直径0.005μm以上100μm以上の細孔容積とした。また細孔直径が5nm以上50nm以下である範囲の累積容積を細孔直径5nm以上50nm以下での細孔容積とした。求めた細孔容積に希土類酸化物の真密度を掛けることで、細孔容積*真密度の値を求めた。使用する真密度の値は一次粒子径の算出に用いたものと同じものを用いた。
(Pore volume*true density for pore diameters of 0.005 μm to 100 μm and pore volume*true density for pore diameters of 5 nm to 50 nm)
The pore volume was measured using an Autopore IV manufactured by Micromeritics.
The cumulative volume in the range of pore diameters of 0.005 μm to 100 μm was defined as the pore volume with a pore diameter of 0.005 μm to 100 μm. The cumulative volume in the range of pore diameters of 5 nm to 50 nm was defined as the pore volume with a pore diameter of 5 nm to 50 nm. The value of pore volume * true density was calculated by multiplying the calculated pore volume by the true density of the rare earth oxide. The value of true density used was the same as that used to calculate the primary particle diameter.
(Na含有量(質量ppm))
サーモフィッシャーサイエンティフィック社製 CE3300FLを用いて原子吸光分析を行った。
(Na content (ppm by mass))
Atomic absorption spectrometry was performed using a Thermo Fisher Scientific CE3300FL.
(結晶子径(nm))
以下のX線回折条件から得られたプロファイルからHalder-Wagner法を用いて結晶子径を求めた。
(X線回折測定条件)
・装置:UltimaIV(株式会社リガク製)
・線源:CuKα線
・管電圧:40kV
・管電流:40mA
・スキャン速度:2度/min・ステップ:0.02度
・スキャン範囲:2θ=20°~90°
(Crystallite size (nm))
The crystallite size was determined by the Halder-Wagner method from a profile obtained under the following X-ray diffraction conditions.
(X-ray diffraction measurement conditions)
・Apparatus: Ultima IV (manufactured by Rigaku Corporation)
Radiation source: CuKα radiation Tube voltage: 40 kV
Tube current: 40mA
Scan speed: 2 degrees/min. Step: 0.02 degrees. Scan range: 2θ = 20° to 90°.
(解砕評価:平均粒子径の測定)
上記で得られたY2O3微粉末を用いて、10質量%のスラリー(分散媒:99.5vol%エタノール)45gを調製し、直径0.1mmのジルコニア製ビーズ240g、周速4m/s、ビーズミル(広島メタル&マシナリー社製 アペックスLABO/A-LABO、有効容量80cc)で解砕した。10分間隔で解砕を止めて下記方法にて平均粒子径を測定した。ただし、平均粒子径が前回測定値より大きくなった場合にその時点でビーズミル処理を終了し、20回(A)を繰り返して2回目から20回目までの各回において前回測定値より平均粒子径が大きくならない場合も、20回(A)を繰り返した時点で終了する。最大20回の繰り返しで最小となる粒径を最小の平均粒子径(Dm)とした。また、解砕直後のデータはビーズミル処理を終了したときの粒径とした(表2の「D0」)。
(Disintegration evaluation: measurement of average particle size)
Using the Y2O3 fine powder obtained above, 45 g of 10 mass% slurry (dispersion medium: 99.5 vol% ethanol) was prepared, and crushed in a bead mill (Apex LABO/A-LABO, manufactured by Hiroshima Metal & Machinery Co., Ltd., effective volume 80 cc) with 240 g of zirconia beads with a diameter of 0.1 mm and a peripheral speed of 4 m/s. Crushing was stopped at 10-minute intervals, and the average particle size was measured by the following method. However, if the average particle size becomes larger than the previous measurement value, the bead mill treatment was terminated at that time, and even if the average particle size does not become larger than the previous measurement value in each of the 20 times (A) of repeating 20 times, the treatment was terminated at the time of repeating 20 times (A). The particle size that is the smallest in the maximum 20 times of repetition was taken as the minimum average particle size (Dm). In addition, the data immediately after crushing was taken as the particle size when the bead mill treatment was terminated ("D0" in Table 2).
(平均粒子径及び多分散指数の測定方法)
大塚電子製ELSZ-2000ZSを用いて適正濃度であると装置が判定してから平均粒子径を測定した。スラリーは溶媒として99.5vol%エタノールを用い上記希釈倍率で希釈した。JIS Z 8828:2019に準拠して測定した、動的光散乱法(光子相関法)によって得られた平均粒子径及び多分散指数を採用した。測定は同一サンプルを3回測定して、3回の平均値を平均粒子径とした。ただし、各回の測定値と3回の平均値との差の絶対値が3回の平均値に対して、1つでも2%を超えていた場合はその測定結果は採用せず、新たに3回の再測定を実施した。測定は25℃にて行った。なお表2に示す多分散指数は解砕評価における最小の平均粒子径(Dm)測定時のものである。
(Method of measuring average particle size and polydispersity index)
The average particle size was measured using Otsuka Electronics' ELSZ-2000ZS after the device determined that the concentration was appropriate. The slurry was diluted at the above dilution ratio using 99.5 vol% ethanol as a solvent. The average particle size and polydispersity index obtained by dynamic light scattering (photon correlation method) measured in accordance with JIS Z 8828:2019 were adopted. The same sample was measured three times, and the average value of the three measurements was taken as the average particle size. However, if the absolute value of the difference between the measured value of each measurement and the average value of the three measurements exceeded 2% for even one of the three average measurements, the measurement result was not adopted, and three new measurements were performed. The measurement was performed at 25°C. The polydispersity index shown in Table 2 is the value when the minimum average particle size (Dm) was measured in the disintegration evaluation.
(解砕7日後の評価)
上記のように解砕評価を行ったスラリーを、常温(20℃)にて7日間静置した。7日静置後の平均粒子径(D7)を上記方法にて測定し、「式:(解砕後7日後の平均粒子径(D7)-解砕直後の平均粒子径(D0))/解砕直後の平均粒子径(D0)×100(%)」の値を計算した。その結果を表2に「(D7-D0)/D0×100(%)」として記載している。また、1週間後のスラリー20mlに対して、40Wの超音波(周波数40kHz)を5分照射した後の平均粒子径も測定した(表2の「D7S」)。
(Evaluation after 7 days of crushing)
The slurry that had been subjected to the disintegration evaluation as described above was allowed to stand for 7 days at room temperature (20°C). The average particle size (D7) after standing for 7 days was measured by the above method, and the value was calculated by the formula: (average particle size 7 days after disintegration (D7) - average particle size immediately after disintegration (D0)) / average particle size immediately after disintegration (D0) x 100 (%). The results are shown in Table 2 as "(D7 - D0) / D0 x 100 (%)". In addition, the average particle size after irradiating 20 ml of the slurry after 1 week with 40 W ultrasonic waves (frequency 40 kHz) for 5 minutes was also measured ("D7S" in Table 2).
また7日静置後の沈降性を下記基準で評価した。
有:容器下部に粒子の塊が目視で確認できる。
無:容器下部に粒子の塊が目視で確認できない。
After standing for 7 days, the settling property was evaluated according to the following criteria.
Yes: Particle clumps can be seen with the naked eye at the bottom of the container.
None: No clumps of particles are visible at the bottom of the container.
更に、7日静置後の可視光透過率(%)を、下記方法にて測定した。
(透過率)
可視吸光光度計(株式会社日立製作所製のU-3100)を用いて350nm~800nmの透過スペクトルを測定した。透過率は350nm~800nmの透過スペクトルの間の最小値を示す。サンプルは解砕時に用いた溶媒30mlに、解砕して得られたスラリー(解砕後1週間後のもの)を0.2ml滴下して調製した。
Furthermore, the visible light transmittance (%) after standing for 7 days was measured by the following method.
(Transmittance)
The transmission spectrum from 350 nm to 800 nm was measured using a visible absorption spectrophotometer (U-3100 manufactured by Hitachi, Ltd.). The transmittance indicates the minimum value between the transmission spectrum from 350 nm to 800 nm. The sample was prepared by dropping 0.2 ml of the slurry obtained by crushing (one week after crushing) into 30 ml of the solvent used during crushing.
(実施例b2)
炭酸水素アンモニウム水溶液と硝酸イットリウム水溶液の混合時の攪拌を、回転数400rpmの低速攪拌とした。また10Lのエタノールではなく、10Lの90vоl%エタノール(10vоl%純水)で残渣を洗浄した。それらの点以外は実施例b1と同様にした。
(Example b2)
The ammonium bicarbonate aqueous solution and the yttrium nitrate aqueous solution were mixed at a low speed of 400 rpm. In addition, the residue was washed with 10 L of 90 vol% ethanol (10 vol% pure water) instead of 10 L of ethanol. Other than these points, the same procedure as in Example b1 was followed.
(実施例b3)
10Lの90vоl%エタノールではなく、10Lの80vоl%エタノール(20vоl%純水)で残渣を洗浄した。その点以外は実施例b2と同様にした。
(Example b3)
The residue was washed with 10 L of 80 vol % ethanol (20 vol % pure water) instead of 10 L of 90 vol % ethanol. Other than that, the same procedure as in Example b2 was followed.
(実施例b4)
10Lの90vоl%エタノールではなく、10Lの50vоl%エタノール(50vоl%純水)で残渣を洗浄した。その点以外は実施例b2と同様にした。
(Example b4)
The residue was washed with 10 L of 50 vol % ethanol (50 vol % pure water) instead of 10 L of 90 vol % ethanol. Other than that, the same procedure as in Example b2 was followed.
(実施例b5)
酸化物換算で50g/L濃度である硝酸イットリウム水溶液(25℃)の代わりに、酸化物換算で50g/L濃度である硝酸イッテルビウム水溶液(25℃)を用いた。その点以外は実施例b1と同様にした。
(Example b5)
Instead of the yttrium nitrate aqueous solution (25° C.) having a concentration of 50 g/L calculated as oxide, an ytterbium nitrate aqueous solution (25° C.) having a concentration of 50 g/L calculated as oxide was used. The rest of the experiment was the same as in Example b1.
(実施例b6)
〔解砕評価〕のビーズミル解砕に供するスラリーの濃度を、10質量%から、4質量%に変更し、分散媒をエタノールからメタノールに変更した。それらの点以外は、実施例b1と同様にした。
(Example b6)
In the [Crushing Evaluation], the concentration of the slurry to be subjected to the bead mill crushing was changed from 10% by mass to 4% by mass, and the dispersion medium was changed from ethanol to methanol. Other than these points, the same procedure was followed as in Example b1.
(実施例b7)
酸化物換算で50g/L濃度である硝酸イットリウム水溶液(25℃)の代わりに、酸化物換算で50g/L濃度である硝酸ジスプロシウム水溶液(25℃)を用いた。その点以外は実施例b1と同様にした。
(Example b7)
Instead of the yttrium nitrate aqueous solution (25° C.) having a concentration of 50 g/L calculated as oxide, a dysprosium nitrate aqueous solution (25° C.) having a concentration of 50 g/L calculated as oxide was used. The rest of the experiment was the same as in Example b1.
(比較例b1)
比較例a1で得た酸化イットリウム微粉末を、比較例b1の酸化イットリウム微粉末とした。
上記の通り、この粉末を走査型電子顕微鏡(SEM)で観察したところ、粒径がおよそ100nmの凝集のない粒径の揃った球状の粒子群であった。比表面積から求める一次粒子径も100nm以上であったため、上記のうち一部の評価は行わなかった。
(Comparative Example b1)
The yttrium oxide fine powder obtained in Comparative Example a1 was used as the yttrium oxide fine powder of Comparative Example b1.
As described above, when this powder was observed with a scanning electron microscope (SEM), it was found to be a group of spherical particles with a uniform particle size of about 100 nm without any agglomeration. Since the primary particle size calculated from the specific surface area was also 100 nm or more, some of the above evaluations were not performed.
(比較例b2)
比較例a2で作製した酸化イットリウム微粉末を、比較例b2の酸化イットリウム微粉末とした。上記の通り、この粉末を走査型電子顕微鏡(SEM)で観察したところ、SEM径がおよそ100nmと10nmの粒子が混在しており、低温焼成ではSEM径が均一な粒子を得られなかった。比表面積から求める一次粒子径も100nm以上であったため、上記のうち一部の評価は行わなかった。
(Comparative Example b2)
The yttrium oxide fine powder prepared in Comparative Example a2 was used as the yttrium oxide fine powder of Comparative Example b2. As described above, when this powder was observed with a scanning electron microscope (SEM), particles with SEM diameters of approximately 100 nm and 10 nm were mixed, and particles with uniform SEM diameters could not be obtained by low-temperature firing. Since the primary particle diameter calculated from the specific surface area was also 100 nm or more, some of the above evaluations were not performed.
(比較例b3)
比較例a3で作製したY2O3を比較例b3の酸化イットリウム微粉末とした。この粉末について、実施例b1に記載の方法で各種測定を行ったほか、解砕評価した。解砕後1週間後のスラリーは凝集して沈降していたため、1週間後の凝集径(「7D」)及び透過率は測定できなかった。また1週間後の超音波照射後の凝集径「7DS」の測定は行っていない。
(Comparative Example b3)
The Y2O3 produced in Comparative Example a3 was used as the yttrium oxide fine powder of Comparative Example b3. This powder was subjected to various measurements by the method described in Example b1, and was also evaluated for disintegration. Since the slurry was aggregated and settled one week after disintegration, the aggregate diameter ("7D") and transmittance after one week could not be measured. Furthermore, the aggregate diameter "7DS" after one week of ultrasonic irradiation was not measured.
(比較例b4)
比較例a4で作製した酸化イットリウム微粉末を、比較例b4の酸化イットリウム微粉末とした。
(Comparative Example b4)
The yttrium oxide fine powder produced in Comparative Example a4 was used as the yttrium oxide fine powder of Comparative Example b4.
(比較例b5)
本比較例はUS2020/0071180Aに相当する例である。
イットリウムイオンの濃度が0.05モル/Lになるように20Lの硝酸イットリウム水溶液を準備した。その水溶液にアセチレングリコール-エチレンオキシド付加物(日信化学工業製サーフィノール485)を21.1g添加した。そしてイットリウムイオンに対して、モル比で15倍の量の尿素を添加した。加水分解反応を進行させるために、95℃に加熱して90分間保持し、その後、室温まで冷却した。加熱中は、攪拌翼により、水溶液をゆっくり攪拌し、容器内で水溶液の温度分布が均一になるようにした。
次に、反応後の液から、遠心分離機を用いて沈殿物を固液分離した。更に、未分解の尿素や残留する硝酸イオンなどを除去するために、回収した固形分を水洗した。次に、得られた希土類化合物粒子を55℃で5日間乾燥後、乾式でビーズミル解砕した。解砕した希土類化合物粒子を600℃で4時間焼成して、酸化イットリウム粒子を得た。得られた酸化イットリウムは一次粒子径が100nm以上であったため、上記のうち一部の評価は行わなかった。
(Comparative Example b5)
This comparative example corresponds to US 2020/0071180A.
20 L of an aqueous yttrium nitrate solution was prepared so that the concentration of yttrium ions was 0.05 mol/L. 21.1 g of an acetylene glycol-ethylene oxide adduct (Surfynol 485 manufactured by Nissin Chemical Industry Co., Ltd.) was added to the aqueous solution. Then, urea was added in an amount 15 times the molar ratio of the yttrium ions. In order to advance the hydrolysis reaction, the solution was heated to 95°C and held for 90 minutes, and then cooled to room temperature. During heating, the aqueous solution was slowly stirred with a stirring blade so that the temperature distribution of the aqueous solution in the container was uniform.
Next, the precipitate was separated from the liquid after the reaction using a centrifuge. Furthermore, the collected solid content was washed with water to remove undecomposed urea and residual nitrate ions. Next, the obtained rare earth compound particles were dried at 55°C for 5 days and then crushed in a dry bead mill. The crushed rare earth compound particles were fired at 600°C for 4 hours to obtain yttrium oxide particles. Since the obtained yttrium oxide had a primary particle diameter of 100 nm or more, some of the above evaluations were not performed.
上記表2の通り、Ce以外の少なくとも1種の希土類元素の酸化物の粉末であって、
一次粒子径が10nm以上100nm未満であり、細孔直径0.005μm以上100μm以下の細孔容積(cm3/g)に真密度(g/cm3)を掛けて得られる数値が3以上14であり、
細孔直径5nm以上50nm以下の細孔容積(cm3/g)に真密度(g/cm3)を掛けて得られる数値が0以上2.0以下である、各実施例の希土類酸化物粉末は、解砕後の粒径が小さく、7日静置後の透過率が高かった。
これに対し、一次粒子径が10nm以上100nm未満の範囲外である比較例b1、b2、b5では解砕後の平均粒子径が大きくなり、7日後の可視光透過率が低かった。また細孔直径0.005μm以上100μm以下の細孔容量(cm3/g)に真密度(g/cm3)を掛けて得られる数値が14超であった比較例b4も、解砕後の平均粒子径が大きくなり、7日後の透過率が低かった。更に、細孔直径5nm以上50nm以下の細孔容積(cm3/g)に真密度(g/cm3)を掛けて得られる数値が2.0超である比較例3は経時で分散質が沈降し、可視光透過率を測定できなかった。
以上より、本発明の希土類酸化物粉末により、分散剤を用いずに高分散スラリーにすることができ、そのスラリーの透明度を安定して保つことができる微粒のCe以外の希土類元素の酸化物粉末を提供できることが判る。
As shown in Table 2 above, a powder of an oxide of at least one rare earth element other than Ce,
the primary particle size is 10 nm or more and less than 100 nm, the value obtained by multiplying the pore volume (cm 3 /g) having a pore diameter of 0.005 μm or more and 100 μm or less by the true density (g/cm 3 ) is 3 or more and 14,
The rare earth oxide powders of each example, in which the value obtained by multiplying the pore volume ( cm3 /g) with a pore diameter of 5 nm or more and 50 nm or less by the true density (g/ cm3 ) was 0 or more and 2.0 or less, had a small particle size after crushing and a high transmittance after being left standing for 7 days.
In contrast, in Comparative Examples b1, b2, and b5, in which the primary particle diameter was outside the range of 10 nm or more and less than 100 nm, the average particle diameter after crushing was large, and the visible light transmittance after 7 days was low. In Comparative Example b4, in which the value obtained by multiplying the pore volume (cm 3 /g) of a pore diameter of 0.005 μm or more and 100 μm or less by the true density (g/cm 3 ) was more than 14, the average particle diameter after crushing was large, and the transmittance after 7 days was low. Furthermore, in Comparative Example 3, in which the value obtained by multiplying the pore volume (cm 3 /g) of a pore diameter of 5 nm or more and 50 nm or less by the true density (g/cm 3 ) was more than 2.0, the dispersoid settled over time, and the visible light transmittance could not be measured.
From the above, it can be seen that the rare earth oxide powder of the present invention can provide a fine oxide powder of a rare earth element other than Ce that can be made into a highly dispersed slurry without using a dispersant and can stably maintain the transparency of the slurry.
第1発明によればCe以外の希土類酸化物において、超音波処理等の簡便な分散処理により、容易に分散でき、薄膜の塗膜の形成が可能な希土類酸化物粉末が提供される。According to the first invention, for rare earth oxides other than Ce, a rare earth oxide powder is provided which can be easily dispersed by a simple dispersion process such as ultrasonic treatment and can form a thin coating film.
第2発明によれば分散剤を使用しないでも高分散スラリーにすることができ、分散状態を維持できるCe以外の希土類元素の酸化物の微粉末が提供される。このような希土類酸化物微粉末は、これを解砕することで、高分散スラリーが得られ、当該スラリーはその分散性に基づいて可視光の透過性を高めたものとすることができる。可視光の透過性を高めることで、希土類酸化物添加の効果を活かしつつ透明性が必要な材料への展開が可能となる。また、希土類イオン特有の狭い波長域のみを吸収するスラリーの提供も可能となる。加えて本発明の希土類酸化物粉末によれば、スラリー中の分散状態を維持できるので、スラリーの透明度を安定して維持できる。According to the second invention, a fine powder of oxides of rare earth elements other than Ce is provided, which can be made into a highly dispersed slurry without using a dispersant and can maintain a dispersed state. By crushing such rare earth oxide fine powder, a highly dispersed slurry can be obtained, and the slurry can have an increased visible light transmittance based on its dispersibility. By increasing the visible light transmittance, it is possible to develop materials that require transparency while taking advantage of the effect of adding rare earth oxides. It is also possible to provide a slurry that absorbs only a narrow wavelength range specific to rare earth ions. In addition, according to the rare earth oxide powder of the present invention, the dispersed state in the slurry can be maintained, so the transparency of the slurry can be stably maintained.
Claims (19)
(a)一次粒子径が10nm以上60nm以下であり、以下の(I)又は(II)を満たすか、又は
(b)一次粒子径が10nm以上100nm未満であり、以下の(III)及び(IV)を満たす、
希土類酸化物粉末。
(I)40W、5分間の超音波分散処理して測定した、レーザー回折・散乱式粒度分布測定法による累積体積100容量%における体積累積粒径D100が1μm以上10μm以下である。
(II)前記希土類元素の酸化物の真密度をρ(g/cm3)としたとき、初期嵩密度ADより下記式1にて算出される空隙率PAD(%)と、タップ嵩密度TDから下記式2で算出される空隙率PTD(%)の差(PAD-PTD)が2.0%以上5.0%以下である。
式1:PAD=(1-AD/ρ) ×100 (%)
式2:PTD=(1-TD/ρ) ×100 (%)
(III)細孔直径0.005μm以上100μm以下の細孔容積(cm3/g)に真密度(g/cm3)を掛けて得られる数値が3以上14以下である。
(IV)細孔直径5nm以上50nm以下の細孔容積(cm3/g)に真密度(g/cm3)を掛けて得られる数値が0以上2.0以下である。 A powder of an oxide of at least one rare earth element other than Ce,
(a) the primary particle size is 10 nm or more and 60 nm or less, and satisfies the following (I) or (II); or (b) the primary particle size is 10 nm or more and less than 100 nm, and satisfies the following (III) and (IV);
Rare earth oxide powder.
(I) The volume cumulative particle size D 100 at 100% cumulative volume measured by a laser diffraction/scattering particle size distribution measurement method after ultrasonic dispersion treatment at 40 W for 5 minutes is 1 μm or more and 10 μm or less.
(II) When the true density of the oxide of the rare earth element is ρ (g/ cm3 ), the difference (P AD - P TD ) between the porosity P AD (%) calculated from the initial bulk density AD using the following formula 1 and the porosity P TD (%) calculated from the tapped bulk density TD using the following formula 2 is 2.0% or more and 5.0% or less.
Formula 1: P AD = (1 - AD / ρ) × 100 (%)
Formula 2: P TD = (1 - TD / ρ) × 100 (%)
(III) The value obtained by multiplying the pore volume (cm 3 /g) of pores having diameters of 0.005 μm or more and 100 μm or less by the true density (g/cm 3 ) is 3 or more and 14 or less.
(IV) The value obtained by multiplying the volume (cm 3 /g) of pores having a diameter of 5 nm or more and 50 nm or less by the true density (g/cm 3 ) is 0 or more and 2.0 or less.
式1:PAD=(1-AD/ρ) ×100 (%) 4. The rare earth oxide powder according to claim 3, wherein the true density of the rare earth oxide is ρ (g/ cm3 ), and the porosity P AD (%) calculated from the initial bulk density AD by the following formula 1 is 90.0% or more and 99.0% or less.
Formula 1: P AD = (1 - AD / ρ) × 100 (%)
(A):直径0.1mmのジルコニア製ビーズを用いて、スラリーに10分間のビーズミル処理を行い、その後、動的光散乱法により平均粒子径を測定する。
(ただし、平均粒子径が前回測定値より大きくなった時点で次の(A)の操作を行わずにビーズミル処理を終了し、20回(A)を繰り返して2回目から20回目までの各回において前回測定値より平均粒子径が大きくならない場合は、20回(A)を繰り返した時点で終了する。
ここで最小となる平均粒子径とは、前記(A)の処理毎にサンプリングして測定した動的光散乱法による平均粒子径の最小値の意味である。) 15. The rare earth oxide powder according to claim 11, wherein when a rare earth oxide powder is mixed with ethanol to prepare an ethanol slurry containing 10% by mass of the rare earth oxide powder, and the following operation (A) is repeatedly performed until the average particle diameter becomes larger than the previous measurement value, the smallest average particle diameter is 10 nm or more and 150 nm or less.
(A): The slurry is subjected to a bead mill treatment for 10 minutes using zirconia beads having a diameter of 0.1 mm, and then the average particle size is measured by a dynamic light scattering method.
(However, when the average particle size becomes larger than the previous measurement value, the bead mill treatment is terminated without performing the next operation (A) , and if the average particle size does not become larger than the previous measurement value in each of the second to twentieth operations of repeating (A) 20 times, the treatment is terminated when (A) has been repeated 20 times.
The minimum average particle size here means the minimum value of the average particle size measured by a dynamic light scattering method by sampling after each treatment of (A).
式:(解砕後7日後の平均粒子径-解砕直後の平均粒子径)/解砕直後の平均粒子径×100(%) The rare earth oxide powder according to claim 15, wherein the calculated value of the following formula is -15% or more and 25% or less.
Formula: (average particle size 7 days after crushing−average particle size immediately after crushing)/average particle size immediately after crushing×100(%)
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