JP5054414B2 - Niobium oxide powder - Google Patents
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- JP5054414B2 JP5054414B2 JP2007108105A JP2007108105A JP5054414B2 JP 5054414 B2 JP5054414 B2 JP 5054414B2 JP 2007108105 A JP2007108105 A JP 2007108105A JP 2007108105 A JP2007108105 A JP 2007108105A JP 5054414 B2 JP5054414 B2 JP 5054414B2
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- 239000000843 powder Substances 0.000 title claims description 71
- URLJKFSTXLNXLG-UHFFFAOYSA-N niobium(5+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Nb+5].[Nb+5] URLJKFSTXLNXLG-UHFFFAOYSA-N 0.000 title claims description 69
- 229910000484 niobium oxide Inorganic materials 0.000 title claims description 67
- 239000011521 glass Substances 0.000 claims description 28
- 230000003595 spectral effect Effects 0.000 claims description 28
- 239000013078 crystal Substances 0.000 claims description 24
- 238000010304 firing Methods 0.000 claims description 20
- 239000010955 niobium Substances 0.000 claims description 15
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 13
- 238000002441 X-ray diffraction Methods 0.000 claims description 12
- 238000004519 manufacturing process Methods 0.000 claims description 11
- 229910052742 iron Inorganic materials 0.000 claims description 7
- 229910052750 molybdenum Inorganic materials 0.000 claims description 7
- 229910052758 niobium Inorganic materials 0.000 claims description 6
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 claims description 6
- 239000000463 material Substances 0.000 claims description 5
- 239000002244 precipitate Substances 0.000 claims description 5
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims description 4
- 239000011733 molybdenum Substances 0.000 claims description 4
- 230000003287 optical effect Effects 0.000 claims description 4
- 238000000034 method Methods 0.000 description 18
- 239000000203 mixture Substances 0.000 description 17
- 239000000047 product Substances 0.000 description 12
- 238000000605 extraction Methods 0.000 description 11
- 238000005259 measurement Methods 0.000 description 11
- 239000007788 liquid Substances 0.000 description 10
- 239000000243 solution Substances 0.000 description 9
- 238000000638 solvent extraction Methods 0.000 description 9
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 8
- 238000002156 mixing Methods 0.000 description 8
- 239000002245 particle Substances 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 7
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 description 7
- 239000012535 impurity Substances 0.000 description 6
- 229910052808 lithium carbonate Inorganic materials 0.000 description 6
- 230000015572 biosynthetic process Effects 0.000 description 5
- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 description 5
- 239000002994 raw material Substances 0.000 description 5
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 4
- NTIZESTWPVYFNL-UHFFFAOYSA-N Methyl isobutyl ketone Chemical compound CC(C)CC(C)=O NTIZESTWPVYFNL-UHFFFAOYSA-N 0.000 description 4
- 238000009826 distribution Methods 0.000 description 4
- 239000003960 organic solvent Substances 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 239000002253 acid Substances 0.000 description 3
- 238000001354 calcination Methods 0.000 description 3
- 239000000919 ceramic Substances 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 238000000746 purification Methods 0.000 description 3
- 238000000790 scattering method Methods 0.000 description 3
- 238000001228 spectrum Methods 0.000 description 3
- 238000005406 washing Methods 0.000 description 3
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 238000004438 BET method Methods 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- UIHCLUNTQKBZGK-UHFFFAOYSA-N Methyl isobutyl ketone Natural products CCC(C)C(C)=O UIHCLUNTQKBZGK-UHFFFAOYSA-N 0.000 description 2
- 229910052783 alkali metal Inorganic materials 0.000 description 2
- 150000001340 alkali metals Chemical class 0.000 description 2
- 235000011114 ammonium hydroxide Nutrition 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000012776 electronic material Substances 0.000 description 2
- 239000005357 flat glass Substances 0.000 description 2
- 238000007496 glass forming Methods 0.000 description 2
- 238000007561 laser diffraction method Methods 0.000 description 2
- ZKATWMILCYLAPD-UHFFFAOYSA-N niobium pentoxide Chemical compound O=[Nb](=O)O[Nb](=O)=O ZKATWMILCYLAPD-UHFFFAOYSA-N 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 238000010298 pulverizing process Methods 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- DLYUQMMRRRQYAE-UHFFFAOYSA-N tetraphosphorus decaoxide Chemical compound O1P(O2)(=O)OP3(=O)OP1(=O)OP2(=O)O3 DLYUQMMRRRQYAE-UHFFFAOYSA-N 0.000 description 2
- 229910052684 Cerium Inorganic materials 0.000 description 1
- YZCKVEUIGOORGS-OUBTZVSYSA-N Deuterium Chemical compound [2H] YZCKVEUIGOORGS-OUBTZVSYSA-N 0.000 description 1
- 229910000592 Ferroniobium Inorganic materials 0.000 description 1
- 206010021143 Hypoxia Diseases 0.000 description 1
- 239000004677 Nylon Substances 0.000 description 1
- 239000003082 abrasive agent Substances 0.000 description 1
- 239000002156 adsorbate Substances 0.000 description 1
- 229910000288 alkali metal carbonate Inorganic materials 0.000 description 1
- 150000008041 alkali metal carbonates Chemical class 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- GHPGOEFPKIHBNM-UHFFFAOYSA-N antimony(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Sb+3].[Sb+3] GHPGOEFPKIHBNM-UHFFFAOYSA-N 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 229910052788 barium Inorganic materials 0.000 description 1
- AYJRCSIUFZENHW-UHFFFAOYSA-L barium carbonate Chemical compound [Ba+2].[O-]C([O-])=O AYJRCSIUFZENHW-UHFFFAOYSA-L 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000012159 carrier gas Substances 0.000 description 1
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000005202 decontamination Methods 0.000 description 1
- 230000003588 decontaminative effect Effects 0.000 description 1
- 229910052805 deuterium Inorganic materials 0.000 description 1
- JKWMSGQKBLHBQQ-UHFFFAOYSA-N diboron trioxide Chemical compound O=BOB=O JKWMSGQKBLHBQQ-UHFFFAOYSA-N 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 229910052736 halogen Inorganic materials 0.000 description 1
- 150000002367 halogens Chemical class 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- 238000002354 inductively-coupled plasma atomic emission spectroscopy Methods 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- ZFGFKQDDQUAJQP-UHFFFAOYSA-N iron niobium Chemical compound [Fe].[Fe].[Nb] ZFGFKQDDQUAJQP-UHFFFAOYSA-N 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 229920001778 nylon Polymers 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 238000000634 powder X-ray diffraction Methods 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 239000006228 supernatant Substances 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
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Description
本発明は、光学材料あるいは電子材料等に使用される酸化ニオブ粉に関する。 The present invention relates to niobium oxide powder used for optical materials or electronic materials.
酸化ニオブ粉は、ガラス等の光学材料や、圧電素子に用いるニオブ酸リチウムの単結晶育成等の電子材料に広く利用されている。特許文献１には、これらの用途に用いられる酸化ニオブ粉として、４５μｍのふるいを通過する割合が９９．９重量％より多く、比表面積が３．５ｍ２／ｇより大きな酸化ニオブ粉が記載されている。
しかし、特許文献１記載の酸化ニオブ粉は、流動性や他の粉末との均一混合性が充分でない場合があった。そこで、本発明者等は、特許文献２のように、ＣｕＫα１線に基づくＸ線回折分析による回折角２θ＝２０°〜３０°の範囲における最大ピークが、半値幅０．０８°〜０．８°である酸化ニオブ粉を提供している。特許文献２の酸化ニオブ粉は、流動性および均一混合性が良好なものである。
しかしながら、特許文献２に記載の酸化ニオブ粉であっても、ガラス形成や単結晶育成においては、好適なものではない場合があった。例えば、酸化ニオブ粉とガラス材料とを混合、溶解してガラスを製造する場合において、溶解が均一に進行し難いことや、脱泡しにくいこと、あるいは得られたガラスの屈折率にムラが発生しやすいことがあった。また、酸化ニオブとアルカリ金属炭酸塩とを混合して焼成し、溶融した焼成品を引き上げて単結晶を育成すると、焼成反応が均一に進行し難い場合や、焼成品の組成割合が安定したものとなりにくい場合があり、得られる単結晶における結晶の組成割合が充分安定していない場合があった。 However, even the niobium oxide powder described in Patent Document 2 may not be suitable for glass formation or single crystal growth. For example, when manufacturing glass by mixing and melting niobium oxide powder and glass material, melting is difficult to proceed uniformly, it is difficult to defoam, or unevenness occurs in the refractive index of the obtained glass It was easy to do. Also, when niobium oxide and alkali metal carbonate are mixed and baked, and the molten baked product is pulled up to grow a single crystal, the baking reaction is difficult to proceed uniformly, or the composition ratio of the baked product is stable In some cases, the composition ratio of crystals in the resulting single crystal is not sufficiently stable.
そこで本発明は、流動性および均一混合性が良好な酸化ニオブ粉であり、ガラス形成に用いた場合、屈折率にムラが発生せず、単結晶育成に用いた場合には、得られる単結晶における結晶の組成割合が充分安定した酸化ニオブ粉の提供を目的とする。 Therefore, the present invention is niobium oxide powder having good fluidity and uniform mixing property, and when used for glass formation, there is no unevenness in the refractive index, and when used for single crystal growth, the obtained single crystal An object of the present invention is to provide niobium oxide powder having a sufficiently stable crystal composition ratio.
上記課題を解決するため、本発明者等は、流動性および均一混合性が良好であり、ガラス形成用途では屈折率にムラが発生せず、単結晶育成用途では焼成品の組成割合が安定した酸化ニオブ粉について鋭意検討を行った。その結果、以下のような酸化ニオブ粉であれば、ガラス形成用途や単結晶育成に用途にも好適な酸化ニオブ粉となることを見出し、本発明に想到するに至った。 In order to solve the above-mentioned problems, the present inventors have good fluidity and uniform mixing property, no unevenness in refractive index occurs in glass forming applications, and the composition ratio of fired products is stable in single crystal growing applications. The niobium oxide powder was studied earnestly. As a result, the following niobium oxide powder was found to be a niobium oxide powder suitable for use in glass formation and single crystal growth, leading to the present invention.
すなわち本発明は、標準白色板を基準として測定した波長５００ｎｍにおける分光反射率が９５％以上であり、波長４００ｎｍにおける分光反射率が７５％以上であり、波長３２０ｎｍにおける分光反射率が１０％以下である酸化ニオブ粉に関する。 That is, in the present invention, the spectral reflectance at a wavelength of 500 nm measured with reference to a standard white plate is 95% or more, the spectral reflectance at a wavelength of 400 nm is 75% or more, and the spectral reflectance at a wavelength of 320 nm is 10% or less. It relates to a certain niobium oxide powder.
本発明の酸化ニオブ粉は、上記した各波長の分光反射率を全て満たしている場合、ガラス形成用途において、ガラスの屈折率にムラが発生せず、単結晶用途では、酸化ニオブ粉と炭酸リチウム等とが充分に混合し、組成割合の安定した焼成品とすることができる。いずれか１の波長において分光反射率の条件を満たさない場合は、ガラス用途において屈折率にムラが発生しやすい場合や、単結晶形成用途において焼成品の組成割合が安定したものとなりにくい傾向がある。波長５００ｎｍにおける分光反射率の大きさは、酸化ニオブ粉の組成割合に影響し、９５％未満では、酸化ニオブ粉が着色しやすいものとなり、酸素欠損が生じやすい。４００ｎｍにおける分光反射率は、組成の均一性に影響し、７５％未満であると、組成割合が安定したものとなりにくい。３２０ｎｍにおける分光反射率は、ガラスを形成した場合等における屈折率に影響し、１０％を超えると、屈折率が均一なものとなりにくい傾向がある。 When the niobium oxide powder of the present invention satisfies all the above-described spectral reflectances at each wavelength, the glass refractive index does not cause unevenness in the glass forming application. In the single crystal application, the niobium oxide powder and the lithium carbonate are used. Etc. can be sufficiently mixed to obtain a fired product having a stable composition ratio. If the spectral reflectance condition is not satisfied at any one of the wavelengths, unevenness in the refractive index is likely to occur in glass applications, or the composition ratio of the fired product tends to be less stable in single crystal formation applications. . The magnitude of the spectral reflectance at a wavelength of 500 nm affects the composition ratio of the niobium oxide powder, and if it is less than 95%, the niobium oxide powder is likely to be colored and oxygen deficiency is likely to occur. The spectral reflectance at 400 nm affects the uniformity of the composition, and if it is less than 75%, the composition ratio is less likely to be stable. The spectral reflectance at 320 nm affects the refractive index when glass is formed, and when it exceeds 10%, the refractive index tends not to be uniform.
分光反射率は、５００ｎｍの反射率が９７％以上、４００ｎｍの反射率が７８％以上、３２０ｎｍの反射率が９％以下であることが好ましく、５００ｎｍの反射率が９８％以上、４００ｎｍの反射率が８０％以上、３２０ｎｍの反射率が８％以下であることがより好ましい。ガラスを形成した場合の屈折率がより均一となり、単結晶育成用の焼成品についても、組成割合が安定したものとすることができるからである。 The spectral reflectance is preferably such that the reflectance at 500 nm is 97% or more, the reflectance at 400 nm is 78% or more, and the reflectance at 320 nm is 9% or less, the reflectance at 500 nm is 98% or more, and the reflectance at 400 nm. Is more preferably 80% or more and 320 nm reflectance is 8% or less. This is because the refractive index when glass is formed becomes more uniform, and the composition ratio of the fired product for growing a single crystal can be made stable.
また、本発明の酸化ニオブ粉は、ガラス原料や炭酸リチウム等と混合して溶融する際、低温において溶融することが可能であり、溶融容器由来の不純物混入を低減することができる。尚、本発明の酸化ニオブ粉は、ニオブを含有する単結晶用途に用いることができるが、Ｌｉ、Ｎａ、Ｋ等から選択される少なくとも１種のアルカリ金属のニオブ酸塩の単結晶に用いることが好ましく、ニオブ酸リチウムの単結晶に用いることが特に好ましい。また、アルカリ金属ニオブ酸塩の単結晶には、Ｍｇ、Ｃａ、Ｂａ、Ｚｎ、Ｚｒ、Ｔｉ、Ｔａ、希土類元素等のうち１種類以上を添加してもよい。 In addition, the niobium oxide powder of the present invention can be melted at a low temperature when mixed with a glass raw material, lithium carbonate, or the like and melted, thereby reducing impurities from the melting vessel. The niobium oxide powder of the present invention can be used for single crystal applications containing niobium, but it is used for at least one alkali metal niobate single crystal selected from Li, Na, K, etc. And is particularly preferably used for a single crystal of lithium niobate. One or more of Mg, Ca, Ba, Zn, Zr, Ti, Ta, rare earth elements, and the like may be added to the alkali metal niobate single crystal.
分光反射率は、分光光度計を用いて、セラミックス製等の標準白色板の反射率を基準とし、酸化ニオブ粉の試料に対し入射角を１０°として測定できる。酸化ニオブ粉の試料としては、例えば、中心にくぼみのあるガラス板に酸化ニオブ粉を入れ、平板ガラスで押し付けた後、過剰な粉体を除去したものを用いることができる。尚、測定は、３２０、４００、５００ｎｍの各波長における反射率を測定してもよく、３２０〜５００ｎｍの波長領域を含む反射スペクトルを測定してもよい。 Spectral reflectance can be measured using a spectrophotometer, with the reflectance of a standard white plate made of ceramics as a reference, and an incident angle of 10 ° with respect to a sample of niobium oxide powder. As a sample of niobium oxide powder, for example, niobium oxide powder placed in a glass plate with a depression in the center, pressed with flat glass, and then excess powder removed can be used. In addition, the measurement may measure the reflectance in each wavelength of 320, 400, 500 nm, and may measure the reflection spectrum containing the wavelength range of 320-500 nm.
本発明の酸化ニオブ粉は、ＣｕＫα線に基づくＸ線回折分析による回折角２θ＝２０°〜３０°の範囲における最大ピークが、２θ＝２２．６°±０．５°又は２θ＝２８．４°±０．５°に位置するものであることが好ましい。流動性が良好なものとなるためである。尚、２θ＝２２．６°±０．５°とは、２θ＝２２．１°〜２３．１°の範囲を、２θ＝２８．４°±０．５°とは、２θ＝２７．９°〜２８．９°の範囲をいう。 In the niobium oxide powder of the present invention, the maximum peak in the range of diffraction angle 2θ = 20 ° to 30 ° by X-ray diffraction analysis based on CuKα ray is 2θ = 22.6 ° ± 0.5 ° or 2θ = 28.4. It is preferable that it is located at ° ± 0.5 °. This is because the fluidity is good. 2θ = 22.6 ° ± 0.5 ° means a range of 2θ = 22.1 ° to 23.1 °, and 2θ = 28.4 ° ± 0.5 ° means 2θ = 27.9. The range from ° to 28.9 °.
また、回折角２θ＝２３．７°±０．５°における最大ピーク強度Ｉｙと２θ＝２２．６°±０．５°における最大ピーク強度Ｉｘとの比Ｉｘ／Ｉｙは、１０以上であることが好ましく、２０以上であることが、より好ましい。Ｉｘ／Ｉｙが１０以上であると、特に流動性や、均一混合性に優れた酸化ニオブ粉とすることができる。以下に示す酸化ニオブ粉の製造工程では、焼成工程を高温で行うと、２θ＝２３．７°±０．５°に最大ピークが出現する傾向があるが、このピーク位置における強度ＩｙがＩｘに対して一定範囲内である場合、ガラス形成や単結晶育成用途に好適な酸化ニオブ粉とすることができるからである。尚、本願において、Ｉｘ及びＩｙは、各波長におけるピーク強度の測定値から、バックグラウンドの強度を差し引いた値を採用することができ、バックグラウンドの強度が測定値の１％以下である場合は、測定値をそのまま使用してもよい。２θ＝２３．７°±０．５°とは、２θ＝２３．２°〜２４．２°の範囲をいう。 The ratio Ix / Iy between the maximum peak intensity Iy at the diffraction angle 2θ = 23.7 ° ± 0.5 ° and the maximum peak intensity Ix at 2θ = 22.6 ° ± 0.5 ° is 10 or more. Is more preferable, and 20 or more is more preferable. When Ix / Iy is 10 or more, niobium oxide powder excellent in fluidity and uniform mixing property can be obtained. In the niobium oxide powder manufacturing process shown below, when the firing process is performed at a high temperature, a maximum peak tends to appear at 2θ = 23.7 ° ± 0.5 °, but the intensity Iy at this peak position is Ix. On the other hand, when it is within a certain range, niobium oxide powder suitable for glass formation and single crystal growth applications can be obtained. In this application, for Ix and Iy, a value obtained by subtracting the background intensity from the measured value of the peak intensity at each wavelength can be adopted, and when the background intensity is 1% or less of the measured value. The measured value may be used as it is. 2θ = 23.7 ° ± 0.5 ° means a range of 2θ = 23.2 ° to 24.2 °.
また、鉄及びモリブデン含有量は、いずれも５質量ｐｐｍ以下であることが好ましく、１質量ｐｐｍ以下であることがより好ましい。鉄やモリブデンのような不純物を多く含有する酸化ニオブ粉は、ガラスを形成した場合に屈折率が均一となりにくく、単結晶育成用途においても、焼成品が均一となりにくいからである。特に、以下に示す製造工程で使用する原料によってはＦｅやＭｏを多く含むものがあるが、得られた酸化ニオブ粉のＦｅ含有量が多いと酸化ニオブ粉が着色されやすく、Ｍｏ含有量が多いと紫外線により着色されやすい。 Moreover, it is preferable that all of iron and molybdenum content are 5 mass ppm or less, and it is more preferable that it is 1 mass ppm or less. This is because niobium oxide powder containing a large amount of impurities such as iron and molybdenum has a refractive index that is difficult to be uniform when glass is formed, and a fired product is difficult to be uniform even in single crystal growth applications. In particular, some raw materials used in the manufacturing process shown below contain a large amount of Fe and Mo, but if the obtained niobium oxide powder has a large Fe content, the niobium oxide powder is likely to be colored, and the Mo content is large. And easily colored by ultraviolet rays.
さらに、本発明の酸化ニオブ粉は、ＢＥＴ法により測定した比表面積が、１〜３０ｍ２／ｇであることが好ましく、２〜２０ｍ２／ｇがより好ましく、３〜１５ｍ２／ｇがさらに好ましい。また、レーザ回折・散乱法粒度分布測定における平均粒径Ｄ５０は、０．５〜１５．０μｍが好ましく、１．０〜１０．０μｍがより好ましく、１．５〜８μｍがさらに好ましい。このような酸化ニオブ粉は、流動性が良好となるからである。 Further, niobium oxide powder of the present invention, the specific surface area measured by the BET method, is preferably from 1-30 m 2 / g, more preferably from 2 to 20 m 2 / g, more preferably 3~15m 2 / g . The average particle size D 50 in the laser diffraction scattering method particle size distribution measurement is preferably 0.5～15.0Myuemu, more preferably 1.0～10.0Myuemu, more preferably 1.5～8Myuemu. This is because such niobium oxide powder has good fluidity.
上記した酸化ニオブ粉は、以下に示す方法により製造することができる。図１に、酸化ニオブ粉の製造工程の概略を示す。具体的には、ニオブを含有する原料を、フッ化水素酸を含有する酸で溶解し、鉱酸や水等を加えた調製液とした後、溶媒抽出してニオブ精製液を得る。そして、アンモニア水等の沈殿剤を添加し、沈殿物を焼成・解砕して、酸化ニオブ粉を製造することができる。 The above-mentioned niobium oxide powder can be produced by the following method. In FIG. 1, the outline of the manufacturing process of niobium oxide powder is shown. Specifically, a niobium-containing raw material is dissolved with an acid containing hydrofluoric acid to prepare a preparation solution to which mineral acid, water, or the like is added, and then a solvent extraction is performed to obtain a niobium purified solution. And niobium oxide powder can be manufactured by adding a precipitating agent such as ammonia water and firing and crushing the precipitate.
沈殿物を生成する際の最終ｐＨは８〜１１であることが好ましい。ｐＨ８未満では、ニオブがニオブ精製液中に残留することがあるため、回収率が低下する傾向があり、ｐＨ１１を超えると、以下に示す好適な焼成条件で焼成した場合においても、得られる酸化ニオブ粉の波長４００ｎｍの反射率が低くなる場合がある。 The final pH when producing the precipitate is preferably 8-11. If the pH is less than 8, niobium may remain in the purified niobium solution, so the recovery rate tends to decrease. If the pH exceeds 11, the obtained niobium oxide can be obtained even when calcined under the suitable calcining conditions shown below. The reflectance of the powder having a wavelength of 400 nm may be lowered.
焼成工程は、７００〜１０００℃に昇温後２時間以上、同様の温度条件を維持して焼成する第１焼成工程の後、４００〜６００℃において５時間以上、同様の温度条件を維持して焼成する第２焼成工程を有することが好ましい。第１焼成工程は、７００℃未満であると、波長３２０ｎｍにおける分光反射率が高くなりやすく、１０００℃を超えると、４００ｎｍにおける分光反射率が低くなりやすいためであり、焼成温度は７５０〜９５０℃とすることがより好ましい。焼成時間は、２時間未満であると、５００ｎｍにおける分光反射率が低くなりやすく、４８時間を超えて焼成しても特に問題はないが、過剰なエネルギー使用となり好ましくない。 After the first baking step, in which the same temperature condition is maintained for 2 hours or more after the temperature is raised to 700 to 1000 ° C., the same temperature condition is maintained for 5 hours or more at 400 to 600 ° C. It is preferable to have a second firing step for firing. The first baking step is because the spectral reflectance at a wavelength of 320 nm tends to be high when the temperature is less than 700 ° C., and the spectral reflectance at 400 nm tends to be low when the temperature exceeds 1000 ° C., and the baking temperature is 750 to 950 ° C. More preferably. If the firing time is less than 2 hours, the spectral reflectance at 500 nm tends to be low, and firing for more than 48 hours is not particularly problematic, but excessive energy is used, which is not preferable.
そして、第２焼成工程を行えば、ガラスを形成した場合に屈折率を均一とし、単結晶育成に用いる焼成品を均一なものとできる酸化ニオブ粉が製造可能となる。第２焼成工程を行わず、第１焼成工程後に、酸化ニオブ粉を４００℃より低い温度に維持した場合や、第２焼成工程を４００℃未満で行うと、波長４００ｎｍにおける分光反射率が低くなりやすく、６００℃を超えると、３２０ｎｍにおける分光反射率が高くなりやすい。焼成時間は、５時間未満であると、４００ｎｍにおける分光反射率が低くなりやすく、４８時間を超えて焼成しても特に問題はないが、過剰なエネルギー使用となり好ましくない。 And if a 2nd baking process is performed, when glass is formed, a refractive index will be made uniform and it will become possible to manufacture the niobium oxide powder which can make the baked product used for single crystal growth uniform. If the niobium oxide powder is maintained at a temperature lower than 400 ° C. after the first baking step without performing the second baking step, or if the second baking step is performed at less than 400 ° C., the spectral reflectance at a wavelength of 400 nm becomes low. When it exceeds 600 ° C., the spectral reflectance at 320 nm tends to be high. If the baking time is less than 5 hours, the spectral reflectance at 400 nm tends to be low, and there is no particular problem even if baking exceeds 48 hours, but excessive energy use is not preferable.
上記したように、第１焼成工程は、第２焼成工程よりも高温で行うことが好ましい。このようにすれば、得られた酸化ニオブ粉の波長４００ｎｍにおける分光反射率を高いものとすることができるからである。一方、第２焼成工程を、第１焼成工程よりも高温とした場合には、４００ｎｍにおける分光反射率が低くなりやすい傾向がある。 As described above, the first firing step is preferably performed at a higher temperature than the second firing step. This is because the resulting niobium oxide powder can have a high spectral reflectance at a wavelength of 400 nm. On the other hand, when the second baking step is performed at a higher temperature than the first baking step, the spectral reflectance at 400 nm tends to be low.
以上で説明したように、本発明に係る酸化ニオブ粉は、ガラスを形成した場合に屈折率を均一なものとし、単結晶育成用途において、炭酸リチウム等と混合した焼成品の組成割合が安定したものとすることができる。 As described above, the niobium oxide powder according to the present invention has a uniform refractive index when glass is formed, and the composition ratio of the fired product mixed with lithium carbonate or the like is stable in single crystal growth applications. Can be.
以下、本発明における最良の実施形態について説明する。 Hereinafter, the best embodiment of the present invention will be described.
図２に示す工程により、Ｔａ抽出用調整液を得た。原料として、フェロニオブ５０００ｋｇを用いて、ジョークラシャーによる粗粉砕、湿式ボールミルによる微粉砕を行い粉砕スラリーを得た。４８％ ＮａＯＨ水溶液を８８００ｋｇ、５時間かけて添加した後、５時間撹拌してアルカリ疎解させ、ろ過して疎解ケーキを得た。次に、１ｍｏｌ／Ｌ 硫酸をｐＨ１．３になるまで添加して酸洗浄ケーキとし、８０％ＨＦ ４２００Ｌで溶解させて、ろ過し、９６％硫酸４００Ｌと水とを添加してＴａ抽出用調整液を得た。この調整液１０００Ｌの組成を調べたところ、Ｔａ ２５．９ｇ／Ｌ、Ｎｂ ２２２ｇ／Ｌ、Ｆｅ ２１ｇ／Ｌ、Ｍｏ １．１ｇ／Ｌ、硫酸 ０．７２ｍｏｌ／Ｌ、ＨＦ １．３ｍｏｌ／Ｌを含有するものであった。 According to the process shown in FIG. 2, an adjustment liquid for Ta extraction was obtained. Using 5000 kg of ferroniobium as a raw material, coarse pulverization with a jaw crusher and fine pulverization with a wet ball mill were performed to obtain a pulverized slurry. After adding 8800 kg of 48% NaOH aqueous solution over 5 hours, the mixture was stirred for 5 hours to cause alkaline decontamination and filtered to obtain a decontaminated cake. Next, 1 mol / L sulfuric acid is added until pH 1.3 to obtain an acid washed cake, dissolved in 4200 L of 80% HF, filtered, and added with 400 L of 96% sulfuric acid and water to prepare a Ta extraction adjustment solution. Got. When the composition of this adjustment liquid 1000 L was examined, Ta 25.9 g / L, Nb 222 g / L, Fe 21 g / L, Mo 1.1 g / L, sulfuric acid 0.72 mol / L, HF 1.3 mol / L were contained. It was something to do.
次に、Ｔａ抽出用調整液を用いて第１溶媒抽出工程を行い、液調整した後、第２溶媒抽出工程を行いＮｂ精製液を得た。第１溶媒抽出工程は、図３に示すように、溶媒には４−メチル−２−ペンタノン（メチルイソブチルケトン、ＭＩＢＫ）を用いて、容量７０Ｌのミキサーセトラーを７段使用した向流抽出によって、Ｔａ抽出用調整液を２．３Ｌ／分、有機溶媒を４．５Ｌ／分流量させてＴａの抽出除去を行った（図３）。そして、Ｔａを除去した調整液に、８０％ＨＦを７００Ｌ添加し、９６％硫酸を１８００Ｌ加えて液調製を行った。 Next, the first solvent extraction process was performed using the adjustment liquid for Ta extraction, and after liquid adjustment, the second solvent extraction process was performed to obtain an Nb purified liquid. As shown in FIG. 3, the first solvent extraction step uses 4-methyl-2-pentanone (methyl isobutyl ketone, MIBK) as a solvent, and countercurrent extraction using seven stages of 70 L mixer settlers. Ta was extracted and removed at a flow rate of 2.3 L / min for the Ta extraction adjustment liquid and 4.5 L / min for the organic solvent (FIG. 3). Then, 700 L of 80% HF was added to the adjustment solution from which Ta was removed, and 1800 L of 96% sulfuric acid was added to prepare a solution.
その後、図４に示すような第２溶媒抽出工程を行い、Ｎｂ精製液を得た。第二溶媒抽出工程は、溶媒としてＭＩＢＫを用い、容量７０Ｌのミキサーセトラーを用い、抽出７段、洗浄１０段、逆抽出１０段で向流抽出を行った。抽出工程でＮｂのほぼ全量と不純物の一部を有機溶媒に抽出し、洗浄工程で有機溶媒中の不純物を除去し、逆抽出工程で洗浄後の有機溶媒中のＮｂを純水に抽出させて、Ｎｂ精製液を得た。尚、第二溶媒抽出工程に用いる各溶液の流量は、表１に示す値として抽出を行った。 Then, the 2nd solvent extraction process as shown in FIG. 4 was performed, and the Nb refinement | purification liquid was obtained. In the second solvent extraction step, MIBK was used as a solvent and a 70-liter mixer settler was used, and countercurrent extraction was performed with 7 extraction stages, 10 washing stages, and 10 back extraction stages. In the extraction process, almost all of Nb and a part of the impurities are extracted into an organic solvent, the impurities in the organic solvent are removed in the washing process, and the Nb in the washed organic solvent is extracted into pure water in the back extraction process. Nb purified solution was obtained. In addition, the flow volume of each solution used for a 2nd solvent extraction process extracted as the value shown in Table 1.
そして、図５に示すように、Ｎｂ精製液により酸化ニオブ粉を得た。まず、Ｎｂ精製液に２５質量％アンモニア水をｐＨ９．０になるまで添加し、沈殿を生成させる。静置後、上澄み液を除去し、さらに純水を注入、撹拌し、沈殿させる工程を３回繰り返して洗浄を行った。洗浄後の沈殿をろ過し、１５０℃で４８時間乾燥させて、焼成後、目開き５００μｍの振動ふるいにて、ナイロンボールを使用して解砕を行い、酸化ニオブ粉を得た。焼成条件は、各実施例について表１に示す温度及び時間で行った。得られた酸化ニオブ粉について行った各種測定試験の結果を表２、表３に示す。 And as shown in FIG. 5, the niobium oxide powder was obtained with the Nb refinement | purification liquid. First, 25 mass% ammonia water is added to Nb refinement | purification liquid until it becomes pH 9.0, and precipitation is produced | generated. After standing, the supernatant was removed, and pure water was poured, stirred and precipitated, and the washing was repeated 3 times. The washed precipitate was filtered, dried at 150 ° C. for 48 hours, fired, and then crushed using a nylon ball with a vibrating screen having an opening of 500 μm to obtain niobium oxide powder. The firing conditions were the temperature and time shown in Table 1 for each example. Tables 2 and 3 show the results of various measurement tests performed on the obtained niobium oxide powder.
[不純物含有量]
酸化ニオブ粉中のＦｅ及びＭｏ含有量については、フッ化水素酸溶解 ＩＣＰ−ＡＥＳ（ＩＣＰ発光分析）法により測定を行った。
[Impurity content]
About content of Fe and Mo in niobium oxide powder, it measured by the hydrofluoric acid melt | dissolution ICP-AES (ICP emission analysis) method.
[分光反射率]
紫外可視近赤外分光光度計 Ｕ−４１００ 固体試料測定システム（日立製作所製）により、入射角を標準側・対照側とも１０°として分光反射率の測定を行った。中心に直径３０ｍｍ、深さ５ｍｍのくぼみを有する４０ｍｍ角のガラス板に、上記方法により得られた各酸化ニオブ粉を約５ｇ乗せ、平板ガラスで押しつけた後、過剰な粉体を除去したものを測定試料とした。反射率１００％の基準は、標準アルミナ焼結板としてベースラインを設定し、各試料について、波長３００〜８００ｎｍの範囲における反射スペクトルを測定した。尚、光源としては、紫外域で重水素ランプ、可視・近赤外域でハロゲンランプを用いて、検出器には光電子倍増管を用いた。スペクトル測定は、スリット幅３．０ｎｍ、スキャン速度３００ｎｍ／ｍｉｎ、光源切替波長３４０ｎｍで行った。
[Spectral reflectance]
The spectral reflectance was measured with an ultraviolet-visible near-infrared spectrophotometer U-4100 solid sample measurement system (manufactured by Hitachi, Ltd.) at an incident angle of 10 ° on both the standard side and the control side. A glass plate with a diameter of 30 mm and a depth of 5 mm is placed on a 40 mm square glass plate with about 5 g of each niobium oxide powder obtained by the above method, pressed with flat glass, and then the excess powder is removed. A measurement sample was obtained. The standard of reflectance 100% set a baseline as a standard alumina sintered plate, and the reflection spectrum in the wavelength range of 300 to 800 nm was measured for each sample. As the light source, a deuterium lamp was used in the ultraviolet region and a halogen lamp was used in the visible / near infrared region, and a photomultiplier tube was used as the detector. The spectrum measurement was performed at a slit width of 3.0 nm, a scanning speed of 300 nm / min, and a light source switching wavelength of 340 nm.
[Ｘ線回折]
Ｘ線回折装置（ＭＸＰ１８：マックサイエンス株式会社製）を用いて、回折角２θ＝２０〜３０°における最大ピーク位置、及び最大ピーク強度の比Ｉｘ／Ｉｙの測定を行った。尚、Ｉｘ又はＩｙのピーク強度とバックグラウンドの強度との差が小さく、Ｉｘ又はＩｙの明確な最大ピークを特定できなかった場合、その波長範囲におけるバックグラウンドの強度のばらつきを考慮してＩｘ又はＩｙの値の上限を定め、Ｉｘ／Ｉｙとして確実に保証できる切の良い値を決定した。具体的には、Ｉｘの最大ピークが明確に特定できなかった場合、「＜０．０５」とし、Ｉｙの最大ピークが明確に特定できなかった場合は、「＞２０」とした。測定には銅ターゲットを使用し、条件は管電圧４０ｋＶ、管電流１５０ｍＡ、測定範囲 ２θ＝１０〜８０°、スキャン速度 ４°／ｍｉｎ、サンプリング幅 ０．０２°として行った。
[X-ray diffraction]
Using an X-ray diffractometer (MXP18: manufactured by Mac Science Co., Ltd.), the maximum peak position at the diffraction angle 2θ = 20 to 30 ° and the maximum peak intensity ratio Ix / Iy were measured. When the difference between the peak intensity of Ix or Iy and the intensity of the background is small and a clear maximum peak of Ix or Iy cannot be specified, the variation of the intensity of the background in the wavelength range is taken into consideration. The upper limit of the value of Iy was determined, and a sharp value that could be reliably guaranteed as Ix / Iy was determined. Specifically, when the maximum peak of Ix could not be clearly specified, “<0.05” was set, and when the maximum peak of Iy could not be clearly specified, “> 20” was set. A copper target was used for the measurement, and the conditions were a tube voltage of 40 kV, a tube current of 150 mA, a measurement range of 2θ = 10 to 80 °, a scan speed of 4 ° / min, and a sampling width of 0.02 °.
[ＢＥＴ法比表面積]
ＪＩＳ Ｒ １６２６−１９９６（ファインセラミックス粉体の気体吸着ＢＥＴ法による比表面積の測定方法）の「６．２ 流動法の（３．５）一点法」に準拠して、セリウム系研摩材の比表面積の測定を行った。その際、キャリアガスには、ヘリウムと吸着質ガスである窒素との混合ガスを使用した。
[BET specific surface area]
In accordance with JIS R 1626-1996 (Method for measuring specific surface area of fine ceramics powder by gas adsorption BET method) “6.2 Flow method (3.5) single point method”, specific surface area of cerium-based abrasives Was measured. At that time, a mixed gas of helium and nitrogen as an adsorbate gas was used as the carrier gas.
[平均粒径Ｄ５０]
レーザ回折・散乱法粒子径分布測定装置（株式会社 堀場製作所製：ＬＡ−９２０）を使用して、各酸化ニオブ粉の粒度分布を測定することにより、平均粒径（Ｄ５０：ＪＩＳ Ｒ １６２９−1996（ファインセラミックス原料のレーザー回折・散乱法による粒子径分布測定方法）に記載されている「体積基準の積算分率における５０％径」）を求めた。
Average particle diameter D 50]
The average particle size (D50: JIS R 1629-1996) is measured by measuring the particle size distribution of each niobium oxide powder using a laser diffraction / scattering method particle size distribution measuring device (Horiba, Ltd .: LA-920). (“50% diameter in volume-based integrated fraction”) described in (Method of measuring particle size distribution by laser diffraction / scattering method of fine ceramic raw material)) was obtained.
[ガラスの屈折率]
各製造方法により得られた酸化ニオブ（Ｎｂ２Ｏ５）３９．８ｇに、炭酸バリウム（ＢａＣＯ３）３１．９ｇ、五酸化リン（Ｐ２Ｏ５）９．０ｇ、酸化硼素（Ｂ２Ｏ３）１．４ｇ、酸化アンチモン（Ｓｂ２Ｏ３）０．０８ｇを混合した。白金坩堝において１４００℃で攪拌しながら加熱、溶融させ、キャスティングして板状のガラスを作製した。ガラスを厚さ５ｍｍにスライスした後、両面を研摩した。ｄ線（５８７．５６ｎｍ）における屈折率を、Ｈｅ光源を用いて測定した。尚、測定は、５ｍｍ間隔で、５点について行い、平均値及び標準偏差を算出した。
[Refractive index of glass]
39.8 g of niobium oxide (Nb 2 O 5 ) obtained by each production method, 31.9 g of barium carbonate (BaCO 3 ), 9.0 g of phosphorus pentoxide (P 2 O 5 ), boron oxide (B 2 O 3) ) 1.4 g and antimony oxide (Sb 2 O 3 ) 0.08 g were mixed. While stirring at 1400 ° C. in a platinum crucible, the mixture was heated, melted, and cast to produce a plate-like glass. After slicing the glass to a thickness of 5 mm, both sides were polished. The refractive index at d-line (587.56 nm) was measured using a He light source. In addition, the measurement was performed for 5 points at intervals of 5 mm, and the average value and the standard deviation were calculated.
[ニオブ酸リチウム焼成粉末 Ｘ線回折ピーク強度比]
各製造方法により得られた酸化ニオブ（Ｎｂ２Ｏ５）と炭酸リチウム（Ｌｉ２ＣＯ３）とを、モル比で０．４８５：０．５１５の一致溶融組成になるよう混合した。上記のモル比で混合した後、８００℃で仮焼した粉末を採取し、銅ターゲットを用いてＸ線回折を行った。測定条件は、上記したＸ線回折と同様の方法とした。得られたＸ線回折ピークから、酸化ニオブに起因する２θ＝２８．３°±０．５°における最大ピーク強度（ＩＮｂ２Ｏ５）とニオブ酸リチウムに起因する２θ＝２３．７°±０．５°における最大ピーク強度（ＩＬＮ）との比〔（ＩＬＮ）／（ＩＮｂ２Ｏ５）〕を算出した。同様の測定を、仮焼後の粉末の５箇所について行い、平均値及び標準偏差を算出した。尚、（ＩＬＮ）／（ＩＮｂ２Ｏ５）の値が大きい場合、仮焼によりニオブ酸リチウムが形成されている割合が多く単結晶育成用途に好適であるが、値が大きい場合であっても、標準偏差が大きいと、得られる単結晶の組成割合が不安定になりやすい。
[Lithium niobate calcined powder X-ray diffraction peak intensity ratio]
Niobium oxide (Nb 2 O 5 ) and lithium carbonate (Li 2 CO 3 ) obtained by the respective production methods were mixed so as to have a congruent melt composition of 0.485: 0.515 in terms of molar ratio. After mixing at the above molar ratio, the powder calcined at 800 ° C. was collected, and X-ray diffraction was performed using a copper target. The measurement conditions were the same as those described above for X-ray diffraction. From the obtained X-ray diffraction peak, the maximum peak intensity (I Nb2O5 ) at 2θ = 28.3 ° ± 0.5 ° caused by niobium oxide and 2θ = 23.7 ° ± 0.5 caused by lithium niobate. The ratio [(I LN ) / (I Nb 2 O 5 )] to the maximum peak intensity (I LN ) at ° was calculated. The same measurement was performed on five places of the powder after calcination, and the average value and the standard deviation were calculated. In addition, when the value of (I LN ) / (I Nb 2 O 5 ) is large, the proportion of lithium niobate formed by calcining is large and suitable for single crystal growth applications, but even when the value is large, When the standard deviation is large, the composition ratio of the obtained single crystal tends to be unstable.
各実施例について検討すると、表１〜３より、実施例１〜１２の酸化ニオブ粉は、波長５００ｎｍにおける反射率が９５％以上、波長４００ｎｍにおける反射率が７５％以上、波長３２０ｎｍにおける反射率が１０％以下であり、鉄及びモリブデンの含有量は、いずれも５質量ｐｐｍ以下で、比表面積が２〜２０ｍ２／ｇ、平均粒径が０．５〜１５μｍの範囲内であった。そして、これらの酸化ニオブ粉でガラスを形成した場合、標準偏差が０．０５以内で屈折率が均一となることが分かった。また、これらの酸化ニオブ粉と炭酸リチウムとを混合した仮焼品は、Ｘ線回折のピーク強度比（ＩＬＮ）／（ＩＮｂ２Ｏ５）の標準偏差が５．０以下であり、焼結品の組成割合が安定したものとなることが示された。 Examining each example, from Tables 1 to 3, the niobium oxide powders of Examples 1 to 12 have a reflectance of 95% or more at a wavelength of 500 nm, a reflectance of 75% or more at a wavelength of 400 nm, and a reflectance at a wavelength of 320 nm. The content of iron and molybdenum was 5 mass ppm or less, the specific surface area was 2 to 20 m 2 / g, and the average particle size was in the range of 0.5 to 15 μm. And when glass was formed with these niobium oxide powder, it turned out that a refractive index becomes uniform within a standard deviation within 0.05. In addition, the calcined product obtained by mixing these niobium oxide powder and lithium carbonate has a standard deviation of the peak intensity ratio (I LN ) / (I Nb 2 O 5 ) of X-ray diffraction of 5.0 or less, It was shown that the composition ratio became stable.
このような実施例１〜１２の酸化ニオブ粉は、第１焼成工程を７００〜１０００℃において５時間、第２焼成工程を４００〜６００℃において１０時間行った場合に得ることができた。また、第１焼成工程を７５０〜９２０℃で行った実施例２〜６の酸化ニオブ粉は、５００ｎｍの反射率が９７％以上、４００ｎｍの反射率が７８％以上、３２０ｎｍの反射率が９％以下であり、ガラスの屈折率は標準偏差０．０４以内となり、炭酸リチウムとの焼成品のＸ線回折のピーク強度比（ＩＬＮ）／（ＩＮｂ２Ｏ５）は標準偏差４．０以下となった。さらに、第１焼成工程を８００〜８８０℃で行った実施例３〜５の酸化ニオブ粉は、５００ｎｍの反射率が９８％以上、４００ｎｍの反射率が８０％以上、３２０ｎｍの反射率が８％以下であり、屈折率は標準偏差０．０３５以内となり、（ＩＬＮ）／（ＩＮｂ２Ｏ５）は標準偏差３．０以下となった。 Such niobium oxide powders of Examples 1 to 12 could be obtained when the first baking step was performed at 700 to 1000 ° C. for 5 hours and the second baking step was performed at 400 to 600 ° C. for 10 hours. In addition, the niobium oxide powders of Examples 2 to 6 in which the first baking step was performed at 750 to 920 ° C. had a reflectance of 500 nm of 97% or more, a 400 nm reflectance of 78% or more, and a 320 nm reflectance of 9%. The refractive index of the glass was within a standard deviation of 0.04, and the peak intensity ratio (I LN ) / (I Nb 2 O 5 ) of the X-ray diffraction of the fired product with lithium carbonate was a standard deviation of 4.0 or less. . Furthermore, the niobium oxide powders of Examples 3 to 5 in which the first baking process was performed at 800 to 880 ° C. had a reflectance of 500 nm of 98% or more, a reflectance of 400 nm of 80% or more, and a reflectance of 320 nm of 8%. The refractive index was within a standard deviation of 0.035, and (I LN ) / (I Nb 2 O 5 ) was a standard deviation of 3.0 or less.
Ｘ線回折のピーク強度比Ｉｘ／Ｉｙが１０未満である実施例７、８は、（ＩＬＮ）／（ＩＮｂ２Ｏ５）の標準偏差が比較的大きいものとなった。これは、第１焼成工程の焼成温度が比較的高温であることにより、２θ＝２３．７°±０．５°に出現するピークの強度が大きくなったためであると考えられる。 In Examples 7 and 8 where the peak intensity ratio Ix / Iy of X-ray diffraction was less than 10, the standard deviation of (I LN ) / (I Nb 2 O 5 ) was relatively large. This is presumably because the intensity of the peak appearing at 2θ = 23.7 ° ± 0.5 ° has increased due to the relatively high firing temperature in the first firing step.
実施例４、１１、１２より、ＦｅやＭｏ等の不純物含有量は、少ないほど波長４００ｎｍ及び５００ｎｍの反射率が高いものとなり、ガラスの屈折率の標準偏差や、炭酸リチウムとの焼成品のＸ線回折のピーク強度比の標準偏差が小さなものとなることが分かった。 From Examples 4, 11, and 12, the smaller the content of impurities such as Fe and Mo, the higher the reflectance at wavelengths of 400 nm and 500 nm, and the standard deviation of the refractive index of the glass and X of the baked product with lithium carbonate. It was found that the standard deviation of the peak intensity ratio of the line diffraction becomes small.
一方、比較例について検討すると、第１焼成工程を７００℃未満で行った比較例１、２は、３２０ｎｍの分光反射率が１０％を超えるものであり、１０００℃を超える比較例３では、４００ｎｍの分光反射率が７５％未満のものとなった。また、第２焼成工程を４００℃未満で行った比較例４では、４００ｎｍの分光反射率が７５％以下となり、６００℃を超える比較例５では、３２０ｎｍの分光反射率が１０％を超えるものとなった。このような分光反射率である比較例１〜６は、ガラス屈折率の標準偏差が０．０８を超えるものであり、（ＩＬＮ）／（ＩＮｂ２Ｏ５）の標準偏差も１０を超えるものであった。 On the other hand, when a comparative example is examined, Comparative Examples 1 and 2 in which the first baking step is performed at less than 700 ° C. have a spectral reflectance of 320 nm exceeding 10%, and Comparative Example 3 exceeding 1000 ° C. is 400 nm. The spectral reflectance was less than 75%. In Comparative Example 4 in which the second baking step was performed at less than 400 ° C., the spectral reflectance at 400 nm was 75% or less, and in Comparative Example 5 exceeding 600 ° C., the spectral reflectance at 320 nm exceeded 10%. became. In Comparative Examples 1 to 6, which are such spectral reflectances, the standard deviation of the glass refractive index exceeds 0.08, and the standard deviation of (I LN ) / (I Nb 2 O 5 ) also exceeds 10. It was.
Ｘ線回折の２θ＝２０〜３０°における最大ピークが、２θ＝２２．６°±０．５°又は２θ＝２８．４°±０．５°のいずれの位置にも現れなかった比較例３は、ガラスの屈折率の標準偏差や、（ＩＬＮ）／（ＩＮｂ２Ｏ５）の標準偏差が大きいものであった。これは、第１焼成工程の焼成温度が１０５０℃と高温であり、２θ＝２３．７°±０．５°に出現するピークの強度が大きくなったためであると考えられる。 Comparative Example 3 in which the maximum peak at 2θ = 20-30 ° of X-ray diffraction did not appear at any position of 2θ = 22.6 ° ± 0.5 ° or 2θ = 28.4 ° ± 0.5 ° Has a large standard deviation of the refractive index of the glass and (I LN ) / (I Nb 2 O 5 ). This is considered to be because the firing temperature in the first firing step is as high as 1050 ° C., and the intensity of the peak appearing at 2θ = 23.7 ° ± 0.5 ° is increased.
Claims (7)
光学材料に用いる酸化ニオブ粉。Niobium oxide powder used for optical materials.
ニオブを含む沈殿物を焼成する焼成処理を備えるものであり、Comprising a firing treatment for firing a precipitate containing niobium,
該沈殿物の焼成処理は、第１焼成工程と第２焼成工程とからなり、第１焼成工程が第２焼成工程より高温で行うことを特徴とする酸化ニオブ粉の製造方法。 The method for producing niobium oxide powder is characterized in that the firing treatment of the precipitate includes a first firing step and a second firing step, and the first firing step is performed at a higher temperature than the second firing step.
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