JP6394324B2 - Barium titanate powder and method for producing the same - Google Patents
Barium titanate powder and method for producing the same Download PDFInfo
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- JP6394324B2 JP6394324B2 JP2014238008A JP2014238008A JP6394324B2 JP 6394324 B2 JP6394324 B2 JP 6394324B2 JP 2014238008 A JP2014238008 A JP 2014238008A JP 2014238008 A JP2014238008 A JP 2014238008A JP 6394324 B2 JP6394324 B2 JP 6394324B2
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- JRPBQTZRNDNNOP-UHFFFAOYSA-N barium titanate Chemical compound [Ba+2].[Ba+2].[O-][Ti]([O-])([O-])[O-] JRPBQTZRNDNNOP-UHFFFAOYSA-N 0.000 title claims description 143
- 229910002113 barium titanate Inorganic materials 0.000 title claims description 143
- 239000000843 powder Substances 0.000 title claims description 68
- 238000004519 manufacturing process Methods 0.000 title claims description 32
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 106
- RQPZNWPYLFFXCP-UHFFFAOYSA-L barium dihydroxide Chemical compound [OH-].[OH-].[Ba+2] RQPZNWPYLFFXCP-UHFFFAOYSA-L 0.000 claims description 83
- 229910001863 barium hydroxide Inorganic materials 0.000 claims description 83
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 claims description 82
- 238000006243 chemical reaction Methods 0.000 claims description 50
- 239000007864 aqueous solution Substances 0.000 claims description 39
- 239000002002 slurry Substances 0.000 claims description 38
- 238000000634 powder X-ray diffraction Methods 0.000 claims description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 29
- 239000002245 particle Substances 0.000 description 27
- 239000000243 solution Substances 0.000 description 23
- 239000010936 titanium Substances 0.000 description 22
- 238000000034 method Methods 0.000 description 20
- ZUDYPQRUOYEARG-UHFFFAOYSA-L barium(2+);dihydroxide;octahydrate Chemical compound O.O.O.O.O.O.O.O.[OH-].[OH-].[Ba+2] ZUDYPQRUOYEARG-UHFFFAOYSA-L 0.000 description 18
- 230000015572 biosynthetic process Effects 0.000 description 15
- 238000003786 synthesis reaction Methods 0.000 description 15
- 229910010413 TiO 2 Inorganic materials 0.000 description 14
- 230000000052 comparative effect Effects 0.000 description 14
- 229910052719 titanium Inorganic materials 0.000 description 14
- XJDNKRIXUMDJCW-UHFFFAOYSA-J titanium tetrachloride Chemical compound Cl[Ti](Cl)(Cl)Cl XJDNKRIXUMDJCW-UHFFFAOYSA-J 0.000 description 14
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 12
- 239000002244 precipitate Substances 0.000 description 8
- LLZRNZOLAXHGLL-UHFFFAOYSA-J titanic acid Chemical compound O[Ti](O)(O)O LLZRNZOLAXHGLL-UHFFFAOYSA-J 0.000 description 8
- 239000013078 crystal Substances 0.000 description 7
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 6
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 6
- 239000010419 fine particle Substances 0.000 description 6
- 239000000126 substance Substances 0.000 description 6
- 229910052788 barium Inorganic materials 0.000 description 5
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 5
- 239000000084 colloidal system Substances 0.000 description 5
- 238000010438 heat treatment Methods 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 238000002844 melting Methods 0.000 description 5
- 230000008018 melting Effects 0.000 description 5
- 239000002994 raw material Substances 0.000 description 5
- AYJRCSIUFZENHW-UHFFFAOYSA-L barium carbonate Chemical compound [Ba+2].[O-]C([O-])=O AYJRCSIUFZENHW-UHFFFAOYSA-L 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 239000002105 nanoparticle Substances 0.000 description 4
- 150000003609 titanium compounds Chemical class 0.000 description 4
- USFZMSVCRYTOJT-UHFFFAOYSA-N Ammonium acetate Chemical compound N.CC(O)=O USFZMSVCRYTOJT-UHFFFAOYSA-N 0.000 description 3
- 239000005695 Ammonium acetate Substances 0.000 description 3
- 238000003917 TEM image Methods 0.000 description 3
- 239000002253 acid Substances 0.000 description 3
- 239000000654 additive Substances 0.000 description 3
- 230000000996 additive effect Effects 0.000 description 3
- -1 alkyl cellosolve Chemical compound 0.000 description 3
- 229940043376 ammonium acetate Drugs 0.000 description 3
- 235000019257 ammonium acetate Nutrition 0.000 description 3
- 239000000706 filtrate Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 239000011164 primary particle Substances 0.000 description 3
- 230000009257 reactivity Effects 0.000 description 3
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 150000004703 alkoxides Chemical class 0.000 description 2
- 230000007062 hydrolysis Effects 0.000 description 2
- 238000006460 hydrolysis reaction Methods 0.000 description 2
- 238000001027 hydrothermal synthesis Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 235000006408 oxalic acid Nutrition 0.000 description 2
- 239000012071 phase Substances 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- 238000003980 solgel method Methods 0.000 description 2
- 238000010532 solid phase synthesis reaction Methods 0.000 description 2
- KPZGRMZPZLOPBS-UHFFFAOYSA-N 1,3-dichloro-2,2-bis(chloromethyl)propane Chemical compound ClCC(CCl)(CCl)CCl KPZGRMZPZLOPBS-UHFFFAOYSA-N 0.000 description 1
- 238000004438 BET method Methods 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 229910001860 alkaline earth metal hydroxide Inorganic materials 0.000 description 1
- 150000001553 barium compounds Chemical class 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 239000003985 ceramic capacitor Substances 0.000 description 1
- 238000002447 crystallographic data Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 230000003472 neutralizing effect Effects 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 239000011541 reaction mixture Substances 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 238000002076 thermal analysis method Methods 0.000 description 1
- 238000009283 thermal hydrolysis Methods 0.000 description 1
- 238000002411 thermogravimetry Methods 0.000 description 1
- 230000004580 weight loss Effects 0.000 description 1
Landscapes
- Inorganic Compounds Of Heavy Metals (AREA)
Description
本発明はチタン酸バリウム粉体とその製造方法に関し、詳しくは、合成度が高く、ＢＥＴ比表面積が大きく、微細であって、好ましい態様によれば、所謂シングルナノサイズのチタン酸バリウム粉体とその製造方法に関する。 The present invention relates to a barium titanate powder and a method for producing the same. Specifically, the synthesis degree is high, the BET specific surface area is large and fine, and according to a preferred embodiment, a so-called single nano-sized barium titanate powder and It relates to the manufacturing method.
近年、種々の電子機器の小型化、高性能化及び軽量化に伴い、これらを構成する素子や、また、それらを製造するための出発原料について、特性の改善が強く求められている。 In recent years, along with the reduction in size, performance and weight of various electronic devices, there is a strong demand for improvement in characteristics of elements constituting them and starting materials for producing them.
例えば、積層セラミックコンデンサ（ＭＬＣＣ）は薄層化が益々強く求められるに至っている一方で、誘電体層や電極層の薄層化技術は飽和してきている。従って、薄層化技術を打開するためには、材料として用いられるチタン酸バリウムの粒子径をより一層微細化することが強く求められている。 For example, while multilayer ceramic capacitors (MLCC) are increasingly required to be thin, dielectric layer and electrode layer thinning techniques are saturated. Therefore, in order to overcome the thinning technology, it is strongly demanded to further reduce the particle diameter of barium titanate used as a material.
チタン酸バリウムの製造方法としては、従来、固相法やシュウ酸法、ゾル−ゲル法等が知られている。しかし、最近のＭＬＣＣの薄層化の求めに応えるために、微粒子、特に、粒径が１００ｎｍ程度以下である微粒子のチタン酸バリウムを製造するには、湿式法である水熱法が有利である。固相法やシュウ酸法は、仮焼工程を含むので、１００ｎｍ以下の微粒子を得難い。ゾル−ゲル法は、高価なアルコキシドを原料として使用するため、製造費用の点において問題がある。 Conventionally known methods for producing barium titanate include a solid phase method, an oxalic acid method, a sol-gel method, and the like. However, in order to meet the recent demand for MLCC thinning, the hydrothermal method, which is a wet method, is advantageous for producing fine particles, particularly fine particles of barium titanate having a particle size of about 100 nm or less. . Since the solid phase method and the oxalic acid method include a calcination step, it is difficult to obtain fine particles of 100 nm or less. Since the sol-gel method uses an expensive alkoxide as a raw material, there is a problem in terms of manufacturing cost.
水熱法によるチタン酸バリウムの製造方法は、従来、既に種々のものが知られている。微粒子のチタン酸バリウムの製造方法の一例として、溶液状態のバリウム化合物に溶液状態又はスラリー状態のチタン化合物を１００〜１２０℃で仕込み、Ｂａ／Ｔｉモル比を３．０〜５０とし、水酸化バリウム初期濃度を１．５〜３．５モル／ｋｇ水として反応させることによって平均粒子径０．０１μｍのチタン酸バリウム粒子を得る方法が知られている（特許文献１参照）。 Various methods for producing barium titanate by the hydrothermal method have already been known. As an example of a method for producing fine-particle barium titanate, a solution-state or slurry-state titanium compound is charged to a solution-state barium compound at 100 to 120 ° C., and a Ba / Ti molar ratio is set to 3.0 to 50. A method is known in which barium titanate particles having an average particle size of 0.01 μm are obtained by reacting at an initial concentration of 1.5 to 3.5 mol / kg water (see Patent Document 1).
この方法によれば、電子顕微鏡観察による平均粒子径が０．０１μｍのチタン酸バリウム粒子が得られるとされているが、電子顕微鏡観察が粒子の一部に限られているので、上記平均粒子径が真に粒子全体の平均粒子径を示しているとはいい難い。更に、客観的な指標であるＢＥＴ比表面積等の記載がなく、合成度についても明らかではない。 According to this method, it is said that barium titanate particles having an average particle diameter of 0.01 μm by electron microscope observation are obtained, but since the electron microscope observation is limited to a part of the particles, the average particle diameter is It is difficult to say that is truly the average particle size of the whole particle. Furthermore, there is no description of the BET specific surface area, which is an objective index, and the degree of synthesis is not clear.
別の一例として、水酸化バリウム水溶液に水酸化チタンコロイドを７０℃で加えて反応させることによって、ＢＥＴ比表面積が１０５ｍ2／ｇ、平均粒子径が１０ｎｍサイズであるチタン酸バリウム粒子を得る方法が提案されている（特許文献２参照）。 As another example, there is a method of obtaining barium titanate particles having a BET specific surface area of 105 m 2 / g and an average particle size of 10 nm by adding a titanium hydroxide colloid to a barium hydroxide aqueous solution at 70 ° C. and causing the reaction. It has been proposed (see Patent Document 2).
しかし、この方法で得られたチタン酸バリウム粒子については、未反応物の残存に関する合成度は不明である。 However, regarding the barium titanate particles obtained by this method, the degree of synthesis regarding the remaining unreacted substance is unknown.
更に、別の一例として、アルカリ土類金属水酸化物のアルキルセロソルブ溶液とチタンアルコキシドを混合し、５０〜１２０℃で熟成することによって、比較的微粒子であるチタン酸バリウム粒子を得る方法も提案されている（特許文献３参照）。しかし、この方法においては、原料として高価なアルコキシドを用いることや有機溶媒を用いること等、経済性や工業生産性に問題がある。 Furthermore, as another example, a method of obtaining barium titanate particles that are relatively fine particles by mixing an alkyl cellosolve solution of an alkaline earth metal hydroxide and titanium alkoxide and aging at 50 to 120 ° C. has been proposed. (See Patent Document 3). However, this method has problems in economic efficiency and industrial productivity such as using an expensive alkoxide as a raw material or using an organic solvent.
本発明は、チタン酸バリウム粉体の製造における上述した問題を解決するためになされたものであって、合成度が高く、ＢＥＴ比表面積が大きく、微細であって、好ましい場合には、ＢＥＴ換算径を平均粒子径とみれば、平均粒子径が所謂シングルナノサイズを有するチタン酸バリウム粉体と、そのようなチタン酸バリウム粉体の製造方法を提供することを目的とする。 The present invention has been made to solve the above-described problems in the production of barium titanate powder, and has a high degree of synthesis, a large BET specific surface area, is fine, and is preferable when converted to BET. When the diameter is regarded as an average particle diameter, an object is to provide a barium titanate powder having a so-called single nanosize average particle diameter and a method for producing such a barium titanate powder.
本発明によれば、水酸化バリウム濃度を３．６〜６．５モル／Ｌの範囲に調整した水酸化バリウム水溶液を８０〜１３０℃の範囲の温度に保ちながら、これにＢＥＴ比表面積が２５０〜５００ｍ2／ｇの範囲にある含水酸化チタンの水スラリーを加え、上記水酸化バリウムと上記含水酸化チタンを０．７〜１．１モル／Ｌの範囲のチタン酸バリウム反応濃度で反応させて、チタン酸バリウムを得ることを特徴とするチタン酸バリウム粉体の製造方法が提供される。 According to the present invention, an aqueous barium hydroxide solution in which the barium hydroxide concentration is adjusted to a range of 3.6 to 6.5 mol / L is maintained at a temperature in the range of 80 to 130 ° C., and the BET specific surface area is 250%. An aqueous slurry of hydrous titanium oxide in the range of ~ 500 m 2 / g is added, and the barium hydroxide and the hydrous titanium oxide are reacted at a barium titanate reaction concentration in the range of 0.7 to 1.1 mol / L. There is provided a method for producing barium titanate powder characterized by obtaining barium titanate.
好ましい態様によれば、上記含水酸化チタンは４００〜５００ｍ2／ｇの範囲のＢＥＴ比表面積を有するものである。 According to a preferred embodiment, the hydrous titanium oxide has a BET specific surface area in the range of 400 to 500 m 2 / g.
また、本発明によれば、ＢＥＴ比表面積が７０〜１５０ｍ2／ｇの範囲にあり、粉末Ｘ線回折によって測定される（１１１）面の結晶子径ｃのＢＥＴ換算径Ｄに対する比率ｃ／Ｄが０．８０〜１．５０の範囲にあることを特徴とするチタン酸バリウム粉体が提供される。 According to the present invention, the BET specific surface area is in the range of 70 to 150 m 2 / g, and the ratio c / D of the crystallite diameter c on the (111) plane measured by powder X-ray diffraction to the BET equivalent diameter D is measured. Is in the range of 0.80 to 1.50. A barium titanate powder is provided.
好ましい態様によれば、ＢＥＴ比表面積が１００〜１５０ｍ2／ｇの範囲にあり、上記比率ｃ／Ｄが１．００〜１．４０の範囲にあるチタン酸バリウム粉体が提供される。 According to a preferred embodiment, a barium titanate powder having a BET specific surface area in the range of 100 to 150 m 2 / g and the ratio c / D in the range of 1.00 to 1.40 is provided.
本発明の方法によれば、合成度が高いと共に、ＢＥＴ比表面積が大きく、微細であって、好ましい態様によれば、ＢＥＴ比表面積が１００ｍ2／ｇ以上であり、従って、ＢＥＴ換算径が所謂シングルナノサイズを有するチタン酸バリウム粉体を得ることができる。 According to the method of the present invention, the degree of synthesis is high, the BET specific surface area is large and fine, and according to a preferred embodiment, the BET specific surface area is 100 m 2 / g or more, and therefore the BET equivalent diameter is so-called. A barium titanate powder having a single nanosize can be obtained.
即ち、本発明によるチタン酸バリウム粉体は、ＢＥＴ比表面積が７０〜１５０ｍ2／ｇの範囲にあり、粉末Ｘ線回折によって測定される（１１１）面の結晶子径ｃのＢＥＴ換算径Ｄに対する比率ｃ／Ｄが０．８０〜１．５０の範囲にあり、好ましい態様によれば、ＢＥＴ比表面積が１００〜１５０ｍ2／ｇの範囲にあり、上記比率ｃ／Ｄが１．００〜１．４０の範囲にある。 That is, the barium titanate powder according to the present invention has a BET specific surface area in the range of 70 to 150 m 2 / g, and the (111) -plane crystallite diameter c measured by powder X-ray diffraction with respect to the BET equivalent diameter D The ratio c / D is in the range of 0.80 to 1.50. According to a preferred embodiment, the BET specific surface area is in the range of 100 to 150 m 2 / g, and the ratio c / D is 1.00 to 1. It is in the range of 40.
本発明によるチタン酸バリウム粉体の製造方法は、水酸化バリウム濃度を３．６〜６．５モル／Ｌの範囲に調整した水酸化バリウム水溶液を８０〜１３０℃の範囲の温度に保ちながら、これにＢＥＴ比表面積が２５０〜５００ｍ2／ｇの範囲にある含水酸化チタンの水スラリーを加え、上記水酸化バリウムと上記含水酸化チタンを０．７〜１．１モル／Ｌの範囲のチタン酸バリウム反応濃度で反応させて、チタン酸バリウムを得るものである。 In the method for producing barium titanate powder according to the present invention, an aqueous barium hydroxide solution having a barium hydroxide concentration adjusted to a range of 3.6 to 6.5 mol / L is maintained at a temperature in the range of 80 to 130 ° C. To this, a water slurry of hydrous titanium oxide having a BET specific surface area in the range of 250 to 500 m 2 / g is added, and the barium hydroxide and the hydrous titanium oxide are added to the titanic acid in the range of 0.7 to 1.1 mol / L. By reacting at a barium reaction concentration, barium titanate is obtained.
本発明において、上記含水酸化チタンは、一般式（Ｉ）
ＴｉＯx・yＨ２Ｏ
（式中、ｘ及びｙは次の式、０＜ｘ≦２、０＜ｙを満たす数である。）
で表されるチタン化合物である。
In the present invention, the hydrous titanium oxide has the general formula (I)
TiO x · yH 2 O
(Wherein x and y are numbers satisfying the following formula, 0 <x ≦ 2, 0 <y)
It is a titanium compound represented by these.
本発明において、水酸化バリウム水溶液の水酸化バリウム濃度を３．６〜６．５モル／Ｌの範囲に調整するには、特に限定されるものではないが、好ましくは、例えば、水酸化バリウム八水塩を融解させて水溶液とし、水酸化バリウム濃度を３．６〜６．５モル／Ｌの範囲に調整する方法によることができる。 In the present invention, the barium hydroxide concentration of the barium hydroxide aqueous solution is not particularly limited in order to adjust the concentration within the range of 3.6 to 6.5 mol / L. This can be done by melting the hydrate to form an aqueous solution and adjusting the barium hydroxide concentration to a range of 3.6 to 6.5 mol / L.
水酸化バリウム八水塩を融解させるには、通常、融点以上、好ましくは、８０℃以上の温度で加熱すればよく、限定されるものではないが、例えば、１００℃に加熱すればよい。 In order to melt the barium hydroxide octahydrate, heating is usually performed at a temperature equal to or higher than the melting point, and preferably equal to or higher than 80 ° C. Although not limited, for example, it may be heated to 100 ° C.
水酸化バリウム水溶液の水酸化バリウム濃度を３．６〜６．５モル／Ｌの範囲に調整するには、例えば、第１の方法として、水酸化バリウム八水塩を融解させて水溶液を得た後、この水溶液に所定量の水を加えて、所定の濃度を有する水酸化バリウム水溶液としてもよいし、また、第２の方法として、水酸化バリウム八水塩に所定量の水を加えた後、加熱し、水酸化バリウム八水塩を融解させて、所定の濃度を有する水酸化バリウム水溶液としてもよい。 In order to adjust the barium hydroxide concentration of the aqueous barium hydroxide solution to a range of 3.6 to 6.5 mol / L, for example, as a first method, an aqueous solution was obtained by melting barium hydroxide octahydrate. Thereafter, a predetermined amount of water may be added to the aqueous solution to form a barium hydroxide aqueous solution having a predetermined concentration. As a second method, after adding a predetermined amount of water to the barium hydroxide octahydrate, The barium hydroxide octahydrate may be melted by heating to obtain an aqueous barium hydroxide solution having a predetermined concentration.
本発明において、水酸化バリウム濃度を３．６〜６．５モル／Ｌの範囲に調整した水酸化バリウム水溶液における上記水酸化バリウム濃度を水酸化バリウム初期濃度といい、また、チタン酸バリウム反応濃度とは、水酸化バリウム水溶液に上述した含水酸化チタンの水スラリーを加えて得られるスラリーにおいて、上記水酸化バリウムと上記含水酸化チタンとの反応によって生成する理論量のチタン酸バリウムの濃度をいう。 In the present invention, the barium hydroxide concentration in an aqueous barium hydroxide solution in which the barium hydroxide concentration is adjusted to a range of 3.6 to 6.5 mol / L is referred to as barium hydroxide initial concentration, and the barium titanate reaction concentration. Means the concentration of a theoretical amount of barium titanate produced by the reaction of the barium hydroxide and the hydrous titanium oxide in a slurry obtained by adding the above-mentioned aqueous slurry of hydrous titanium oxide to an aqueous barium hydroxide solution.
本発明において用いる上記含水酸化チタンは、ＢＥＴ比表面積が２５０〜５００ｍ2／ｇの範囲にあることが必要である。含水酸化チタンのＢＥＴ比表面積が２５０ｍ2／ｇよりも小さいときは、得られるチタン酸バリウムはＢＥＴ比表面積が７０ｍ2／ｇよりも小さくなるか、又は後述する合成度が低くなるので、用いるに適しない。ＢＥＴ比表面積５００ｍ2／ｇを超える含水酸化チタンは製造が困難である。 The hydrous titanium oxide used in the present invention needs to have a BET specific surface area in the range of 250 to 500 m 2 / g. When the hydrous titanium oxide has a BET specific surface area of less than 250 m 2 / g, the resulting barium titanate has a BET specific surface area of less than 70 m 2 / g, or the degree of synthesis described later is low. Not suitable. It is difficult to produce hydrous titanium oxide having a BET specific surface area of more than 500 m 2 / g.
特に、本発明によれば、ＢＥＴ比表面積が４００〜５００ｍ2／ｇの範囲にある含水酸化チタンを用いることによって、ＢＥＴ比表面積が１００ｍ2／ｇ以上、即ち、ＢＥＴ換算径が１０ｎｍ未満のシングルナノサイズのチタン酸バリウム粉体を得ることができる。 In particular, according to the present invention, by using hydrous titanium oxide having a BET specific surface area in the range of 400 to 500 m 2 / g, a BET specific surface area of 100 m 2 / g or more, that is, a BET equivalent diameter of less than 10 nm Nano-sized barium titanate powder can be obtained.
本発明において用いる含水酸化チタンは、結晶質であっても、非晶質であってもよく、結晶質であるとき、アナターゼ型、ルチル型、ブルカイト型のいずれであってもよいし、また、これらの２種以上の混合物であってもよい。チタンアルコキシド、四塩化チタン水溶液、水溶性チタン等は液状であって、チタン酸バリウムの工業的な製造において、このような液状の原料を用いることは、経済的に不利であり、本発明において用いるに適さない。 The hydrous titanium oxide used in the present invention may be crystalline or amorphous, and when it is crystalline, it may be any of anatase type, rutile type, brookite type, A mixture of two or more of these may be used. Titanium alkoxide, titanium tetrachloride aqueous solution, water-soluble titanium and the like are in a liquid state, and it is economically disadvantageous to use such a liquid raw material in the industrial production of barium titanate, and is used in the present invention. Not suitable for.
上述したようにＢＥＴ比表面積が２５０〜５００ｍ2／ｇの範囲にある含水酸化チタンは四塩化チタンの熱加水分解や四塩化チタンとアルカリ水溶液との中和反応によって沈殿物として得ることができる。 As described above, hydrous titanium oxide having a BET specific surface area in the range of 250 to 500 m 2 / g can be obtained as a precipitate by thermal hydrolysis of titanium tetrachloride or neutralization reaction between titanium tetrachloride and an aqueous alkali solution.
詳しくは、アナターゼ型含水酸化チタンとルチル型含水酸化チタンは、四塩化チタン水溶液を約６０℃からその沸点程度に加熱して加水分解することによって、沈殿物として得ることができる。加水分解時に酢酸アンモニウムのような添加剤を共存させることによって、アナターゼ型とルチル型含水酸化チタンの一方を選択的に生成させることができる。非晶質含水酸化チタンは、例えば、予め、四塩化チタン水溶液とアルカリ水溶液を常温で同時に水中に加え、同時中和することによって、沈殿物として得ることができる。また、製法や反応条件によっては、アナターゼ型及び／又はルチル型及び／又はブルカイト型含水酸化チタンと非晶質含水酸化チタンとの混合物を沈殿物として得ることができる。 Specifically, the anatase-type hydrous titanium oxide and the rutile-type hydrous titanium oxide can be obtained as precipitates by heating an aqueous titanium tetrachloride solution from about 60 ° C. to the boiling point thereof for hydrolysis. By making an additive such as ammonium acetate coexist at the time of hydrolysis, either anatase type or rutile type hydrous titanium oxide can be selectively produced. The amorphous hydrous titanium oxide can be obtained as a precipitate, for example, by previously adding a titanium tetrachloride aqueous solution and an alkali aqueous solution into water at room temperature at the same time and simultaneously neutralizing them. Depending on the production method and reaction conditions, a mixture of anatase-type and / or rutile-type and / or brookite-type hydrous titanium oxide and amorphous hydrous titanium oxide can be obtained as a precipitate.
このようにして得られた含水酸化チタンの沈殿物は、これを純水に分散させてスラリーとして、本発明によるチタン酸バリウムの製造における原料として用いる。尚、得られたスラリーは、必要に応じて、酸等を用いて解膠して用いてもよい。 The hydrous titanium oxide precipitate thus obtained is dispersed in pure water as a slurry and used as a raw material in the production of barium titanate according to the present invention. In addition, you may use the obtained slurry by peptizing using an acid etc. as needed.
本発明によれば、水酸化バリウム濃度を３．６〜６．５モル／Ｌの範囲に調整した水酸化バリウム水溶液と、これに前記含水酸化チタンの水スラリーを加えて得られるスラリーについても、これを水酸化バリウムと含水酸化チタンとの反応が終了するまで、８０℃から１３０℃までの温度に保つ。 According to the present invention, a barium hydroxide aqueous solution having a barium hydroxide concentration adjusted to a range of 3.6 to 6.5 mol / L, and a slurry obtained by adding an aqueous slurry of the hydrous titanium oxide to this, This is maintained at a temperature of 80 ° C. to 130 ° C. until the reaction between barium hydroxide and hydrous titanium oxide is completed.
即ち、本発明によれば、前記初期濃度を有する水酸化バリウム水溶液を調製し、８０〜１３０℃の範囲の温度に保ちつつ、これに上述したＢＥＴ比表面積が２５０〜５００ｍ2／ｇの範囲にある含水酸化チタンの水スラリーを加え、チタン酸バリウム反応濃度を０．７〜１．１モル／Ｌの範囲として水酸化バリウムと含水酸化チタンを反応させてチタン酸バリウムを得る。 That is, according to the present invention, an aqueous barium hydroxide solution having the initial concentration is prepared and maintained at a temperature in the range of 80 to 130 ° C., while the BET specific surface area is in the range of 250 to 500 m 2 / g. An aqueous slurry of hydrous titanium oxide is added, and barium titanate is reacted at a barium titanate reaction concentration in the range of 0.7 to 1.1 mol / L to obtain barium titanate.
本発明において、水酸化バリウム水溶液と含水酸化チタンの水スラリーを混合して、水酸化バリウムと含水酸化チタンを反応させる際の反応温度は重要である。反応温度が８０℃よりも低いときは、水酸化バリウムと含水酸化チタンの反応性が低くなり、得られるチタン酸バリウムは合成度が低い。一方、混合温度が１３０℃を超えるときは、反応は進行するものの、得られるチタン酸バリウムは粒子径が大きくなり、ＢＥＴ比表面積が７０ｍ2／ｇ以上の微細なチタン酸バリウム粉体を得ることが困難である。水酸化バリウム水溶液と含水酸化チタンの水スラリーを混合して、水酸化バリウムと含水酸化チタンを反応させる際の反応温度は、好ましくは、８０〜１２０℃の範囲である。 In the present invention, the reaction temperature when the barium hydroxide aqueous solution and the aqueous slurry of hydrous titanium oxide are mixed to react the barium hydroxide with the hydrous titanium oxide is important. When the reaction temperature is lower than 80 ° C., the reactivity between barium hydroxide and titanium hydroxide is low, and the resulting barium titanate has a low degree of synthesis. On the other hand, when the mixing temperature exceeds 130 ° C., the reaction proceeds, but the obtained barium titanate has a large particle diameter, and a fine barium titanate powder having a BET specific surface area of 70 m 2 / g or more is obtained. Is difficult. The reaction temperature when the barium hydroxide aqueous solution and the hydrous titanium oxide aqueous slurry are mixed to react the barium hydroxide with the hydrous titanium oxide is preferably in the range of 80 to 120 ° C.
また、本発明においては、上記水酸化バリウムと前記含水酸化チタンとの反応によってチタン酸バリウムを得るに際して、水酸化バリウムと含水酸化チタンは、水酸化バリウム水溶液に含水酸化チタンのスラリーを加え終わった時点で、Ｂａ／Ｔｉモル比が１．１〜３．０の範囲であるように用いることが好ましい。上記水酸化バリウムと含水酸化チタンの反応において、Ｂａ／Ｔｉモル比が１．１よりも小さいときは、アルカリ度が低いため、水酸化バリウムと含水酸化チタンの反応性が悪い。一方、Ｂａ／Ｔｉモル比が３．０よりも大きいときは、水酸化バリウムと含水酸化チタンの反応性には問題はないが、反応に寄与しない水酸化バリウムを過剰に用いるので、製造費用が徒に高くなる問題がある。 In the present invention, when barium titanate is obtained by the reaction of the barium hydroxide with the hydrous titanium oxide, the barium hydroxide and the hydrous titanium oxide have finished adding the slurry of hydrous titanium oxide to the barium hydroxide aqueous solution. At this point, it is preferable to use the Ba / Ti molar ratio in the range of 1.1 to 3.0. In the reaction of barium hydroxide and hydrous titanium oxide, when the Ba / Ti molar ratio is smaller than 1.1, the alkalinity is low, and the reactivity between barium hydroxide and hydrous titanium oxide is poor. On the other hand, when the Ba / Ti molar ratio is larger than 3.0, there is no problem in the reactivity of barium hydroxide and hydrous titanium oxide, but since barium hydroxide that does not contribute to the reaction is used excessively, the production cost is low. There is a problem that gets higher.
本発明の方法においては、水酸化バリウム水溶液における水酸化バリウム初期濃度とチタン酸バリウム反応濃度も重要である。ＢＥＴ比表面積が２５０〜５００ｍ2／ｇの範囲にある含水酸化チタンを用いても、水酸化バリウム初期濃度とチタン酸バリウム反応濃度が共に本発明において規定する濃度よりも小さいときは、ＢＥＴ比表面積が７０ｍ2／ｇ以上の微細なチタン酸バリウム粉体を得ることができないか、又は得られるチタン酸バリウムが後述する合成度において低い。 In the method of the present invention, the initial barium hydroxide concentration and the barium titanate reaction concentration in the barium hydroxide aqueous solution are also important. Even when a hydrous titanium oxide having a BET specific surface area in the range of 250 to 500 m 2 / g is used, when both the initial barium hydroxide concentration and the barium titanate reaction concentration are smaller than the concentration specified in the present invention, the BET specific surface area Cannot obtain a fine barium titanate powder of 70 m 2 / g or more, or the obtained barium titanate is low in the degree of synthesis described later.
一方、水酸化バリウムの初期濃度が高いほど、また、チタン酸バリウム反応濃度が高いほど、得られるチタン酸バリウムの粒子径は小さくなるが、従来の技術では、水酸化バリウムは溶解度が低く、更に、水酸化バリウムが完全に溶解していない水酸化バリウム水溶液を用いて、含水酸化チタンと反応させた場合、反応が不均一に進行するので、得られるチタン酸バリウムは粒子の大きさが不揃いであり、しかも、大粒子が生成する。 On the other hand, the higher the initial concentration of barium hydroxide and the higher the barium titanate reaction concentration, the smaller the particle size of the barium titanate obtained, but in the prior art, barium hydroxide has lower solubility, In the case of reacting with hydrous titanium oxide using a barium hydroxide aqueous solution in which barium hydroxide is not completely dissolved, the reaction proceeds non-uniformly, so that the obtained barium titanate has irregular particle sizes. In addition, large particles are produced.
しかし、本発明によれば、前述したように、例えば、水酸化バリウム八水和物を融点以上の温度に加熱し、融解させ、必要に応じて、水酸化バリウム八水塩を融解させる前後に水を用いて、前記初期濃度を有する水酸化バリウム水溶液を調製し、これに前述した高ＢＥＴ比表面積を有する含水酸化チタンの水スラリーを加えて、水酸化バリウムと含水酸化チタンを反応させることによって、ＢＥＴ比表面積が７０ｍ2／ｇ以上、好ましい態様によれば、１００ｍ2／ｇ以上の微細なチタン酸バリウム粉体を得ることができる。 However, according to the present invention, as described above, for example, the barium hydroxide octahydrate is heated to a temperature equal to or higher than the melting point and melted, and before and after the barium hydroxide octahydrate is melted as necessary. By preparing an aqueous barium hydroxide solution having the above initial concentration using water, adding the aqueous slurry of hydrous titanium oxide having a high BET specific surface area described above, and reacting barium hydroxide with the hydrous titanium oxide. According to a preferred embodiment, a fine barium titanate powder having a BET specific surface area of 70 m 2 / g or more and 100 m 2 / g or more can be obtained.
しかし、水酸化バリウムと含水酸化チタンとの反応において、チタン酸バリウム反応濃度が余りに高いときは、反応混合物が高粘度となり、反応が不均一に進行して、目的とする微細なチタン酸バリウム粉体を得ることができない。本発明においては、チタン酸バリウムの反応濃度を１．１モル／Ｌ以下として、水酸化バリウムと含水酸化チタンを反応させるのが好ましい。一方、チタン酸バリウム反応濃度が０．７モル／Ｌより低いときは、微細なチタン酸バリウム粉体を得ることができず、しかも、得られるチタン酸バリウム粉体は合成度が低い。 However, in the reaction of barium hydroxide and hydrous titanium oxide, if the reaction concentration of barium titanate is too high, the reaction mixture becomes highly viscous and the reaction proceeds non-uniformly, resulting in the desired fine barium titanate powder. I can't get a body. In the present invention, it is preferable that the reaction concentration of barium titanate is 1.1 mol / L or less to react barium hydroxide with hydrous titanium oxide. On the other hand, when the barium titanate reaction concentration is lower than 0.7 mol / L, a fine barium titanate powder cannot be obtained, and the obtained barium titanate powder has a low degree of synthesis.
本発明の方法によれば、このようにして得られるチタン酸バリウムスラリーを濾過し、水洗した後、乾燥することによって、目的とするチタン酸バリウム粉体を得ることができる。 According to the method of the present invention, the barium titanate slurry thus obtained can be filtered, washed with water, and then dried to obtain the target barium titanate powder.
即ち、本発明によれば、ＢＥＴ比表面積が７０〜１５０ｍ2／ｇの範囲にあり、好ましい態様によれば、１００〜１４０ｍ2／ｇの範囲にあり、最も好ましくは、１１０〜１３０ｍ2／ｇの範囲にあり、更に、Ｘ線回折によって測定される（１１１）面の結晶子径ｃのＢＥＴ換算径Ｄに対する比率ｃ／Ｄが０．８０〜１．５０の範囲にあり、好ましくは、１．００〜１．４０の範囲にあって、合成度が高く、未反応物の残存が少ない微細なチタン酸バリウム粉体を得ることができる。 That is, according to the present invention, BET specific surface area is in the range of 70~150m 2 / g, according to a preferred embodiment, in the range of 100~140m 2 / g, and most preferably, 110~130m 2 / g Further, the ratio c / D of the crystallite diameter c of the (111) plane to the BET equivalent diameter D measured by X-ray diffraction is in the range of 0.80 to 1.50, preferably 1 A fine barium titanate powder having a high degree of synthesis and a small amount of unreacted substances in the range of 0.001 to 1.40 can be obtained.
ここで、本発明において、合成度の指標として用いているＸ線回折によって測定される（１１１）面の結晶子径ｃのＢＥＴ換算径Ｄに対する比率ｃ／Ｄについて説明する。先ず、上記結晶子径ｃはチタン酸バリウムが単結晶とみなせる場合、１次粒子径と結晶子径は等しく、チタン酸バリウムが単結晶でない場合には、結晶子径は１次粒子径よりも小さくなることが知られている。本発明においては、後述するように、得られるチタン酸バリウムは単結晶とみなすことができ、従って、結晶子径をチタン酸バリウムの１次粒子径とみることができる。 Here, the ratio c / D of the crystallite diameter c of the (111) plane to the BET equivalent diameter D measured by X-ray diffraction used as an index of the degree of synthesis in the present invention will be described. First, when the barium titanate can be regarded as a single crystal, the crystallite diameter c is equal to the primary particle diameter and the crystallite diameter. When the barium titanate is not a single crystal, the crystallite diameter is larger than the primary particle diameter. It is known to become smaller. In the present invention, as will be described later, the obtained barium titanate can be regarded as a single crystal, and therefore the crystallite diameter can be regarded as the primary particle diameter of barium titanate.
次に、上記ＢＥＴ換算径は、ＢＥＴ法によって求められる比表面積（即ち、ＢＥＴ比表面積）と同一の表面積を有する球の直径に相当する。ＢＥＴ換算径Ｄは、次式の換算式によって求めることができる。 Next, the BET equivalent diameter corresponds to the diameter of a sphere having the same surface area as that obtained by the BET method (that is, the BET specific surface area). The BET equivalent diameter D can be obtained by the following equation.
Ｄ＝［６／（Ｓｇ×ρ）］×１０００
ここに、ＤはＢＥＴ換算径（ｎｍ）、Ｓｇは粒子のＢＥＴ比表面積（ｍ2／ｇ）、ρは粒子の密度（ｇ／ｃｍ3）である。チタン酸バリウムの密度の値は６．０とした。
D = [6 / (Sg × ρ)] × 1000
Here, D is the BET equivalent diameter (nm), Sg is the BET specific surface area (m 2 / g) of the particle, and ρ is the particle density (g / cm 3 ). The density value of barium titanate was 6.0.
得られたチタン酸バリウムに、例えば、原料含水酸化チタンや塩化物イオンのような未反応物が残存しているときは、上記式においてＢＥＴ比表面積は高くなり、その結果、ＢＥＴ換算径は小さくなる。即ち、未反応物が残存することによって、見かけ上のＢＥＴ比表面積が高くなり、ＢＥＴ換算径が小さくなる。 In the obtained barium titanate, for example, when an unreacted material such as raw material hydrous titanium oxide or chloride ions remains, the BET specific surface area is high in the above formula, and as a result, the BET equivalent diameter is small. Become. That is, the remaining unreacted material increases the apparent BET specific surface area and decreases the BET equivalent diameter.
従って、上記比率ｃ／Ｄが１に近いほど、合成度が高く、結晶性が高いチタン酸バリウムであるということができる。上記比率ｃ／Ｄが１より大きい場合、未反応物が残存することによって、見かけ上のＢＥＴ比表面積が高くなり、ＢＥＴ換算径が小さくなっている状態であるということができる。上記比率ｃ／Ｄが１よりも小さい場合、（１１１）面の結晶子径が小さいということであるから、結晶性が低いということができる。本発明の方法によれば、上記比率が０．８０〜１．５０の範囲にあり、好ましい態様によれば、１．００〜１．４０の範囲にあって、合成度の高いチタン酸バリウムを得ることができる。 Therefore, it can be said that the closer the ratio c / D is to 1, the higher the degree of synthesis and the higher the crystallinity of the barium titanate. When the ratio c / D is larger than 1, it can be said that the unreacted substance remains, whereby the apparent BET specific surface area is increased and the BET equivalent diameter is reduced. When the ratio c / D is smaller than 1, it means that the crystallite diameter of the (111) plane is small, and it can be said that the crystallinity is low. According to the method of the present invention, the ratio is in the range of 0.80 to 1.50. According to a preferred embodiment, barium titanate having a high degree of synthesis is in the range of 1.00 to 1.40. Can be obtained.
このように、本発明によって得られるチタン酸バリウム粉体は、ＢＥＴ比表面積が７０ｍ2／ｇ以上の微細な粒子からなり、合成度が高いもの、即ち、未反応物が少ない高純度微細なチタン酸バリウム粒子からなる。特に、本発明によれば、ＢＥＴ比表面積が４００〜５００ｍ2／ｇの範囲にある前記含水酸化チタンを用いることによって、ＢＥＴ比表面積が１００ｍ2／ｇ以上、即ち、ＢＥＴ換算径が１０ｎｍ未満のシングルナノサイズのチタン酸バリウム粉体を得ることができる。 Thus, the barium titanate powder obtained by the present invention is composed of fine particles having a BET specific surface area of 70 m 2 / g or more, and has a high degree of synthesis, that is, high-purity fine titanium with little unreacted material. It consists of barium acid particles. In particular, according to the present invention, by using the hydrous titanium oxide having a BET specific surface area in the range of 400 to 500 m 2 / g, the BET specific surface area is 100 m 2 / g or more, that is, the BET equivalent diameter is less than 10 nm. Single nano-sized barium titanate powder can be obtained.
このようなチタン酸バリウム粉体は、加熱減量が少なく、ＭＬＣＣ用ペーストの添加剤等に用いる場合、焼結時のクラック等を防止することができる。それ故に、本発明によるチタン酸バリウム粉体は薄層化に対応したＭＬＣＣの製造に好適に用いることができる。 Such a barium titanate powder has little loss on heating, and when used as an additive or the like of an MLCC paste, cracks during sintering can be prevented. Therefore, the barium titanate powder according to the present invention can be suitably used for the production of MLCC corresponding to thinning.
以下に実施例を挙げて本発明を説明するが、本発明はこれら実施例により何ら限定されるものではない。
実施例１
（アナターゼ型含水酸化チタンの製造）
四塩化チタン水溶液（（株）大阪チタニウムテクノロジーズ製、ＴｉＯ2 換算で３．８モル／Ｌ）８０ｍＬに酢酸アンモニウム２３．８ｇを加えて水溶液を調製し、これを７０℃に加熱して、四塩化チタンを熱加水分解した。得られた沈殿物を濾過し、これを濾液の電導度が５ｍＳ／ｍ以下になるまで純水で洗浄した。このようにして得られたアナターゼ型含水酸化チタンはＢＥＴ比表面積が４１６ｍ2／ｇであった。このアナターゼ型含水酸化チタンを水に分散させて、ＴｉＯ2換算で１．４モル／Ｌ濃度のスラリーとした。
EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.
Example 1
(Manufacture of anatase type hydrous titanium oxide)
An aqueous solution was prepared by adding 23.8 g of ammonium acetate to 80 mL of an aqueous titanium tetrachloride solution (manufactured by Osaka Titanium Technologies Co., Ltd., 3.8 mol / L in terms of TiO 2 ). Titanium was thermally hydrolyzed. The obtained precipitate was filtered, and washed with pure water until the conductivity of the filtrate was 5 mS / m or less. The anatase-type hydrous titanium oxide thus obtained had a BET specific surface area of 416 m 2 / g. This anatase type hydrous titanium oxide was dispersed in water to obtain a slurry having a concentration of 1.4 mol / L in terms of TiO 2 .
（チタン酸バリウムの製造）
１Ｌ容量の反応容器に水酸化バリウム八水和物（堺化学工業（株）製、純度９６％、以下、同じ。）２２０ｇを入れ、１００℃に加熱して、水酸化バリウム八水和物を融解させ、水酸化バリウム濃度６．１モル／Ｌの水酸化バリウム水溶液を得た。
(Manufacture of barium titanate)
Into a reaction vessel of 1 L capacity, 220 g of barium hydroxide octahydrate (manufactured by Sakai Chemical Industry Co., Ltd., purity 96%, the same applies hereinafter) was heated to 100 ° C., and barium hydroxide octahydrate was added. By melting, an aqueous barium hydroxide solution having a barium hydroxide concentration of 6.1 mol / L was obtained.
上記水酸化バリウム水溶液を温度１００℃に保ちながら、これに上記アナターゼ型含水酸化チタンスラリーを３０分で加え、チタン酸バリウム反応濃度０．９１モル／Ｌにて温度１００℃で３０分間反応させて、チタン酸バリウムのスラリーを得た。上記水酸化バリウム水溶液に上記アナターゼ型含水酸化チタンのスラリーを加え終わった時点のＢａ／Ｔｉモル比は２．２であった。反応後、得られたチタン酸バリウムのスラリーを濾過し、水洗した後、１３０℃で乾燥して、チタン酸バリウム粉体を得た。 While maintaining the barium hydroxide aqueous solution at a temperature of 100 ° C., the anatase-type hydrous titanium oxide slurry was added to this in 30 minutes and reacted at a barium titanate reaction concentration of 0.91 mol / L at a temperature of 100 ° C. for 30 minutes. A slurry of barium titanate was obtained. The Ba / Ti molar ratio when the addition of the anatase-type hydrous titanium oxide slurry to the barium hydroxide aqueous solution was 2.2 was 2.2. After the reaction, the obtained barium titanate slurry was filtered, washed with water, and dried at 130 ° C. to obtain a barium titanate powder.
図１に上記チタン酸バリウム粉体の粉末Ｘ線回折パターンを示し、図２に上記チタン酸バリウム粉体の加熱減量のグラフを示し、図３に熱収縮挙動を示し、図４に上記チタン酸バリウム粒子の透過型電子顕微鏡写真を示す。 FIG. 1 shows a powder X-ray diffraction pattern of the barium titanate powder, FIG. 2 shows a graph of the heat loss of the barium titanate powder, FIG. 3 shows the heat shrinkage behavior, and FIG. 4 shows the titanate. A transmission electron micrograph of barium particles is shown.
実施例２
１Ｌ容量の反応容器に水酸化バリウム八水和物を入れ、１００℃に加熱し、水酸化バリウム八水和物を融解させて、水酸化バリウム水溶液を得た。この水酸化バリウム水溶液を１００℃に保ちながら、これに水５６ｍＬを加え、４．０モル／Ｌ濃度の水酸化バリウム水溶液を得た。
Example 2
Barium hydroxide octahydrate was put into a 1 L reaction vessel and heated to 100 ° C. to melt the barium hydroxide octahydrate to obtain an aqueous barium hydroxide solution. While maintaining this barium hydroxide aqueous solution at 100 ° C., 56 mL of water was added thereto to obtain a 4.0 mol / L concentration barium hydroxide aqueous solution.
以下、チタン酸バリウム反応濃度を０．７７モル／Ｌとして、水酸化バリウムと含水酸化チタンを反応させた以外は、実施例１と同様にして、チタン酸バリウム粉体を得た。 Thereafter, barium titanate powder was obtained in the same manner as in Example 1 except that the reaction concentration of barium titanate was 0.77 mol / L, and barium hydroxide and titanium hydroxide were reacted.
実施例３
（非晶質含水酸化チタンの製造）
四塩化チタン水溶液（（株）大阪チタニウムテクノロジーズ製、ＴｉＯ2 換算で２．０モル／Ｌ）１５０ｍＬと水酸化ナトリウム水溶液（５．０モル／Ｌ）をｐＨ９で同時中和して、非晶質含水酸化チタンを得た。この非晶質含水酸化チタンのＢＥＴ比表面積は４２７ｍ2／ｇであった。この非晶質含水酸化チタンを水に分散させて、ＴｉＯ2 換算で１．４モル／Ｌ濃度のスラリーを得た。
Example 3
(Production of amorphous hydrous titanium oxide)
Titanium tetrachloride aqueous solution (produced by Osaka Titanium Technologies Co., Ltd., 2.0 mol / L in terms of TiO 2 ) and sodium hydroxide aqueous solution (5.0 mol / L) were simultaneously neutralized at pH 9 to be amorphous. Hydrous titanium oxide was obtained. The amorphous hydrous titanium oxide had a BET specific surface area of 427 m 2 / g. This amorphous hydrous titanium oxide was dispersed in water to obtain a slurry having a concentration of 1.4 mol / L in terms of TiO 2 .
（チタン酸バリウムの製造）
以下、チタン酸バリウム反応濃度を０．９１モル／Ｌとして、水酸化バリウムと非晶質含水酸化チタンを反応させた以外は、実施例１と同様にして、チタン酸バリウム粉体を得た。
(Manufacture of barium titanate)
Thereafter, barium titanate powder was obtained in the same manner as in Example 1 except that barium titanate reaction concentration was 0.91 mol / L and barium hydroxide and amorphous hydrous titanium oxide were reacted.
実施例４
（アナターゼ型含水酸化チタンの製造）
四塩化チタン水溶液（（株）大阪チタニウムテクノロジーズ製、ＴｉＯ2 換算で２．０モル／Ｌ）１５０ｍＬを温度６０℃で水酸化ナトリウム水溶液（５．０モル／Ｌ）にてｐＨ２．５で中和して、アナターゼ型含水酸化チタンを得た。このアナターゼ型含水酸化チタンのＢＥＴ比表面積は２５５ｍ2／ｇであった。このアナターゼ型含水酸化チタンを水に分散させて、ＴｉＯ2 換算で１．４モル／Ｌ濃度のスラリーを得た。
Example 4
(Manufacture of anatase type hydrous titanium oxide)
150 mL of titanium tetrachloride aqueous solution (manufactured by Osaka Titanium Technologies Co., Ltd., 2.0 mol / L in terms of TiO 2 ) was neutralized at a temperature of 60 ° C. with an aqueous sodium hydroxide solution (5.0 mol / L) at pH 2.5. Thus, anatase type hydrous titanium oxide was obtained. The anatase type hydrous titanium oxide had a BET specific surface area of 255 m 2 / g. This anatase type hydrous titanium oxide was dispersed in water to obtain a slurry having a concentration of 1.4 mol / L in terms of TiO 2 .
（チタン酸バリウムの製造）
上記アナターゼ型含水酸化チタンの水スラリーを用いると共に、水酸化バリウム初期濃度６．１モル／Ｌの水酸化バリウム水溶液を用い、チタン酸バリウム反応濃度を０．９１モル／Ｌとした以外は、実施例１と同様にして、チタン酸バリウム粉体を得た。
(Manufacture of barium titanate)
This was carried out except that the water slurry of the anatase-type hydrous titanium oxide was used, an aqueous barium hydroxide solution having an initial barium hydroxide concentration of 6.1 mol / L was used, and the barium titanate reaction concentration was 0.91 mol / L. In the same manner as in Example 1, barium titanate powder was obtained.
実施例５
実施例４において、水酸化バリウム初期濃度４．０モル／Ｌの水酸化バリウム水溶液を用い、チタン酸バリウム反応濃度を０．７７モル／Ｌとした以外は、実施例１と同様にして、チタン酸バリウム粉体を得た。
Example 5
In Example 4, the same procedure as in Example 1 was used except that an aqueous barium hydroxide solution having an initial barium hydroxide concentration of 4.0 mol / L was used and the barium titanate reaction concentration was 0.77 mol / L. Barium acid powder was obtained.
実施例６
（アナターゼ型含水酸化チタンの製造）
四塩化チタン水溶液（（株）大阪チタニウムテクノロジーズ製、ＴｉＯ2 換算で３．８モル／Ｌ）１６０ｍＬに酢酸アンモニウム４７．７ｇを加えて水溶液を調製し、これを７０℃に加熱して、四塩化チタンを熱加水分解した。得られた沈殿物を濾過し、これを濾液の電導度が５ｍＳ／ｍ以下になるまで純水で洗浄した。このようにして得られたアナターゼ型含水酸化チタンはＢＥＴ比表面積が３９６ｍ2／ｇであった。このアナターゼ型含水酸化チタンを水に分散させて、ＴｉＯ2 換算で１．５モル／Ｌ濃度のスラリーとした。
Example 6
(Manufacture of anatase type hydrous titanium oxide)
An aqueous solution was prepared by adding 47.7 g of ammonium acetate to 160 mL of titanium tetrachloride aqueous solution (manufactured by Osaka Titanium Technologies, 3.8 mol / L in terms of TiO 2 ), and heated to 70 ° C. to obtain tetrachloride. Titanium was thermally hydrolyzed. The obtained precipitate was filtered, and washed with pure water until the conductivity of the filtrate was 5 mS / m or less. The thus obtained anatase type hydrous titanium oxide had a BET specific surface area of 396 m 2 / g. This anatase type hydrous titanium oxide was dispersed in water to obtain a slurry having a concentration of 1.5 mol / L in terms of TiO 2 .
（チタン酸バリウムの製造）
１Ｌ容量の反応容器に水酸化バリウム八水和物４４０ｇを入れ、８５℃に加熱して、水酸化バリウム八水和物を融解させ、水酸化バリウム濃度６．１モル／Ｌの水酸化バリウム水溶液を得た。
(Manufacture of barium titanate)
440 g of barium hydroxide octahydrate is placed in a 1 L reaction vessel, heated to 85 ° C. to melt the barium hydroxide octahydrate, and an aqueous barium hydroxide solution having a barium hydroxide concentration of 6.1 mol / L. Got.
上記水酸化バリウム水溶液を温度８５℃に保ちながら、これに上記アナターゼ型含水
酸化チタンスラリーを３０分で加え、チタン酸バリウム反応濃度０．９１モル／Ｌにて温
度８５℃で３０分間反応させた以外は、実施例１と同様にして、チタン酸バリウム粉体を得た。
While maintaining the barium hydroxide aqueous solution at a temperature of 85 ° C., the anatase-type hydrous titanium oxide slurry was added thereto in 30 minutes, and reacted at a barium titanate reaction concentration of 0.91 mol / L at a temperature of 85 ° C. for 30 minutes. Except for this, barium titanate powder was obtained in the same manner as in Example 1.
実施例７
（チタン酸バリウムの製造）
１Ｌ容量の反応容器に水酸化バリウム八水和物４４０ｇを入れ、１１５℃に加熱して、水酸化バリウム八水和物を融解させ、水酸化バリウム濃度６．１モル／Ｌの水酸化バリウム水溶液を得た。
Example 7
(Manufacture of barium titanate)
440 g of barium hydroxide octahydrate is placed in a 1 L reaction vessel, heated to 115 ° C. to melt the barium hydroxide octahydrate, and an aqueous barium hydroxide solution having a barium hydroxide concentration of 6.1 mol / L. Got.
上記水酸化バリウム水溶液を温度１１５℃に保ちながら、これに実施例６と同様にして得られたアナターゼ型含水酸化チタンスラリーを３０分で加え、チタン酸バリウム反応濃度０．９１モル／Ｌにて温度１１５℃で５分間反応させた以外は、実施例１と同様にして、チタン酸バリウム粉体を得た。 While maintaining the above barium hydroxide aqueous solution at a temperature of 115 ° C., the anatase-type hydrous titanium oxide slurry obtained in the same manner as in Example 6 was added in 30 minutes to a barium titanate reaction concentration of 0.91 mol / L. A barium titanate powder was obtained in the same manner as in Example 1 except that the reaction was performed at 115 ° C. for 5 minutes.
実施例８
（アナターゼ型とルチル型の混合含水酸化チタンの製造）
四塩化チタン水溶液（（株）大阪チタニウムテクノロジーズ製、ＴｉＯ2 換算で３．８モル／Ｌ）１６０ｍＬを７０℃に加熱して、四塩化チタンを熱加水分解した。得られた沈殿物を濾過し、これを濾液の電導度が５ｍＳ／ｍ以下になるまで純水で洗浄した。このようにして得られた含水酸化チタンはＢＥＴ比表面積が２８２ｍ2／ｇであり、アナターゼ型は３１％、ルチル型は６９％であった。このアナターゼ型とルチル型の混合含水酸化チタンを水に分散させて、ＴｉＯ2 換算で１．５モル／Ｌ濃度のスラリーとした。
Example 8
(Production of mixed hydrous titanium oxide of anatase type and rutile type)
160 mL of an aqueous titanium tetrachloride solution (manufactured by Osaka Titanium Technologies, Ltd., 3.8 mol / L in terms of TiO 2 ) was heated to 70 ° C. to thermally hydrolyze the titanium tetrachloride. The obtained precipitate was filtered, and washed with pure water until the conductivity of the filtrate was 5 mS / m or less. The hydrous titanium oxide thus obtained had a BET specific surface area of 282 m 2 / g, anatase type was 31%, and rutile type was 69%. This mixed hydrous titanium oxide of anatase type and rutile type was dispersed in water to obtain a slurry having a concentration of 1.5 mol / L in terms of TiO 2 .
（チタン酸バリウムの製造）
上記アナターゼ型とルチル型の混合含水酸化チタンの水スラリーを用いて、この含水酸化チタンと水酸化バリウムを２０分間、反応させた以外は、実施例１と同様にして、チタン酸バリウム粉体を得た。
(Manufacture of barium titanate)
A barium titanate powder was prepared in the same manner as in Example 1 except that the hydrous titanium oxide and barium hydroxide were reacted for 20 minutes by using the water slurry of the mixed hydrous titanium oxide of the anatase type and the rutile type. Obtained.
比較例１
（アナターゼ型含水酸化チタンの製造）
実施例１と同様にして、ＴｉＯ2 換算で１．４モル／Ｌ濃度のアナターゼ型含水酸化チタンのスラリーを得た。
Comparative Example 1
(Manufacture of anatase type hydrous titanium oxide)
In the same manner as in Example 1, a slurry of anatase type hydrous titanium oxide having a concentration of 1.4 mol / L in terms of TiO 2 was obtained.
（チタン酸バリウムの製造）
１Ｌ容量の反応容器に水酸化バリウム八水和物２２０ｇを入れ、常温でこれに純水２２０ｍＬを加えて溶解させ、１００℃に加熱して、水酸化バリウム濃度２．０モル／Ｌの水酸化バリウム水溶液を得た。
(Manufacture of barium titanate)
In a 1 L reaction vessel, 220 g of barium hydroxide octahydrate is added, dissolved at room temperature with 220 mL of pure water, heated to 100 ° C., and oxidized with a barium hydroxide concentration of 2.0 mol / L. An aqueous barium solution was obtained.
上記水酸化バリウム水溶液を温度１００℃に保ちながら、これに上記アナターゼ型含水酸化チタンのスラリーを３０分で加えた後、ＢａＴｉＯ3 換算で０．５１モル／Ｌのチタン酸バリウム反応濃度で温度１００℃で３０分間反応させて、チタン酸バリウムのスラリーを得た。水酸化バリウム水溶液に含水酸化チタンのスラリーを加え終わった時点のＢａ／Ｔｉモル比は２．２であった。反応後、得られたチタン酸バリウムのスラリーを濾過し、水洗した後、１３０℃で乾燥して、チタン酸バリウム粉体を得た。 While maintaining the barium hydroxide aqueous solution at a temperature of 100 ° C., the anatase-type hydrous titanium oxide slurry was added to this in 30 minutes, and then at a barium titanate reaction concentration of 0.51 mol / L in terms of BaTiO 3 , the temperature was 100. The mixture was reacted at 30 ° C. for 30 minutes to obtain a barium titanate slurry. The Ba / Ti molar ratio when the addition of the hydrous titanium oxide slurry to the barium hydroxide aqueous solution was 2.2 was 2.2. After the reaction, the obtained barium titanate slurry was filtered, washed with water, and dried at 130 ° C. to obtain a barium titanate powder.
比較例２
ＢＥＴ比表面積９９ｍ2／ｇのアナターゼ型酸化チタン（昭和タイタニウム(株)製）を水に分散させて、ＴｉＯ2 換算で１．４モル／Ｌ濃度の水スラリーを得た。このスラリーを用いた以外は、比較例１と同様にして、チタン酸バリウム粉体を得た。
Comparative Example 2
An anatase type titanium oxide (manufactured by Showa Titanium Co., Ltd.) having a BET specific surface area of 99 m 2 / g was dispersed in water to obtain a water slurry having a concentration of 1.4 mol / L in terms of TiO 2 . A barium titanate powder was obtained in the same manner as in Comparative Example 1 except that this slurry was used.
比較例３
実施例１と同様にして、温度１００℃、濃度６．１モル／Ｌの水酸化バリウム水溶液を調製した。比較例２において、上記水酸化バリウム水溶液を用い、チタン酸バリウム反応濃度を０．９１モル／Ｌとした以外は、比較例１と同様にして、チタン酸バリウム粉体を得た。
Comparative Example 3
In the same manner as in Example 1, an aqueous barium hydroxide solution having a temperature of 100 ° C. and a concentration of 6.1 mol / L was prepared. In Comparative Example 2, a barium titanate powder was obtained in the same manner as in Comparative Example 1 except that the above barium hydroxide aqueous solution was used and the barium titanate reaction concentration was 0.91 mol / L.
比較例４
（水酸化チタンコロイド（ＴｉＣｌ2.85 ＯＨ1.15）の製造）
特許文献２（特開２００７−１３７７５９号公報）の実施例１に準じて、水酸化バリウム八水和物（堺化学工業（株）製）５０ｇを純水１２０ｍＬに８０℃で溶解させ、これを四塩化チタン水溶液（（株）大阪チタニウムテクノロジーズ製、ＴｉＯ2換算で３．８モル／Ｌ）４０ｍＬに加えて、水酸化チタンコロイド（ＴｉＣｌ2.85 ＯＨ1.15）を得た。
Comparative Example 4
(Production of titanium hydroxide colloid (TiCl 2.85 OH 1.15 ))
In accordance with Example 1 of Patent Document 2 (Japanese Patent Laid-Open No. 2007-137759), 50 g of barium hydroxide octahydrate (manufactured by Sakai Chemical Industry Co., Ltd.) was dissolved in 120 mL of pure water at 80 ° C. Titanium hydroxide colloid (TiCl 2.85 OH 1.15 ) was obtained in addition to 40 mL of titanium tetrachloride aqueous solution (manufactured by Osaka Titanium Technologies, Ltd., 3.8 mol / L in terms of TiO 2 ).
（チタン酸バリウムの製造）
次に、水酸化バリウム八水和物１４０ｇを純水１４０ｍＬに入れ、７０℃に加熱し、溶解させて水溶液を得、これを温度７０℃、ｐＨ１２．７で窒素雰囲気下の反応容器中に保持した。上記水酸化バリウム水溶液に上記水酸化チタンコロイドを２０秒で加えて、７０℃で２時間反応させた。上記水酸化バリウム水溶液に上記水酸化チタンコロイドを加えた後のＢａ／Ｔｉモル比は３．０であった。かくして得られたチタン酸バリウムのスラリーを濾過し、水洗した後、１３０℃で乾燥して、チタン酸バリウム粉体を得た。
(Manufacture of barium titanate)
Next, 140 g of barium hydroxide octahydrate is put into 140 mL of pure water, heated to 70 ° C. and dissolved to obtain an aqueous solution, which is kept in a reaction vessel in a nitrogen atmosphere at a temperature of 70 ° C. and pH 12.7. did. The titanium hydroxide colloid was added to the barium hydroxide aqueous solution in 20 seconds and reacted at 70 ° C. for 2 hours. The Ba / Ti molar ratio after adding the titanium hydroxide colloid to the barium hydroxide aqueous solution was 3.0. The barium titanate slurry thus obtained was filtered, washed with water, and then dried at 130 ° C. to obtain a barium titanate powder.
図２にこのチタン酸バリウム粉体の加熱減量のグラフを示し、図３に熱収縮挙動を示す。 FIG. 2 shows a graph of the heat loss of the barium titanate powder, and FIG. 3 shows the heat shrinkage behavior.
比較例５
１Ｌ容量の反応容器に水酸化バリウム八水和物６９３ｇを入れ、これに純水６９３ｍＬを加えて溶解させ、１００℃に加熱して、水酸化バリウム濃度２．１モル／Ｌの水酸化バリウム水溶液を得た。
Comparative Example 5
Into a 1 L reaction vessel, 693 g of barium hydroxide octahydrate is added, 693 mL of pure water is added and dissolved therein, heated to 100 ° C., and an aqueous barium hydroxide solution having a barium hydroxide concentration of 2.1 mol / L. Got.
上記水酸化バリウム水溶液を温度９０℃に保ちながら、これに四塩化チタン水溶液（（株）大阪チタニウムテクノロジーズ製、ＴｉＯ2 換算で１．０モル／Ｌ）３０ｍＬを３０分で加えた後、ＢａＴｉＯ3 換算で０．２８モル／Ｌのチタン酸バリウム反応濃度で温度９０℃で３０分間反応させて、チタン酸バリウムのスラリーを得た。上記水酸化バリウム水溶液に上記四塩化チタン水溶液を加え終わった時点のＢａ／Ｔｉモル比は７０であった。 While maintaining the barium hydroxide aqueous solution at a temperature of 90 ° C., 30 mL of titanium tetrachloride aqueous solution (manufactured by Osaka Titanium Technologies Co., Ltd., 1.0 mol / L in terms of TiO 2 ) was added in 30 minutes, and then BaTiO 3 Reaction was performed at a barium titanate reaction concentration of 0.28 mol / L in terms of temperature at 90 ° C. for 30 minutes to obtain a barium titanate slurry. The Ba / Ti molar ratio when the addition of the titanium tetrachloride aqueous solution to the barium hydroxide aqueous solution was 70 was 70.
反応後、チタン酸バリウムのスラリーを濾過し、水洗した後、１３０℃で乾燥して、チタン酸バリウム粉体を得た。 After the reaction, the barium titanate slurry was filtered, washed with water, and dried at 130 ° C. to obtain a barium titanate powder.
図１に上記チタン酸バリウム粉体の粉末Ｘ線回折パターンを示す。得られたチタン酸バリウムは炭酸バリウムを含むことが示されている。 FIG. 1 shows a powder X-ray diffraction pattern of the barium titanate powder. The resulting barium titanate has been shown to contain barium carbonate.
上記実施例１〜８及び比較例１〜５におけるチタン酸バリウムの製造条件、即ち、水酸化バリウム初期濃度、用いたチタン化合物の種類と結晶形とＢＥＴ比表面積、水酸化バリウムとチタン化合物との反応におけるＢａ／Ｔｉ仕込みモル比と反応条件を表１に示す。また、上記実施例１〜８及び比較例１〜５において得られたチタン酸バリウム粉体の物性を表２に示す。 Production conditions of barium titanate in Examples 1 to 8 and Comparative Examples 1 to 5, that is, the initial concentration of barium hydroxide, the type and crystal form of the titanium compound used, the BET specific surface area, the barium hydroxide and the titanium compound Table 1 shows the Ba / Ti charge molar ratio and reaction conditions in the reaction. Table 2 shows the physical properties of the barium titanate powders obtained in Examples 1 to 8 and Comparative Examples 1 to 5.
（含水酸化チタンの結晶構造）
含水酸化チタン粉体の粉末Ｘ線回折装置（（株）リガク製ＲＩＮＴ−ＴＴＲIII、線源ＣｕＫα）による回折データからその結晶構造を確認した。
（含水酸化チタン粉末とチタン酸バリウム粉末のＢＥＴ比表面積）
含水酸化チタン粉末とチタン酸バリウム粉末のＢＥＴ比表面積は全自動比表面積測定装置（（株）マウンテック製ＨＭ１２２０）を用いて測定した。含水酸化チタンは１２０℃、チタン酸バリウムは２０５℃で３０分脱気した後、ＢＥＴ１点法で測定した。
（チタン酸バリウム粉体のＢＥＴ換算径）
チタン酸バリウム粉体のＢＥＴ換算径は、チタン酸バリウムの密度を６．０ｇ／ｃｍ3として、上記チタン酸バリウムのＢＥＴ比表面積を用いて前述した換算式によって算出した。
（チタン酸バリウムの結晶子径）
チタン酸バリウム粉体の粉末Ｘ線回折装置（（株）リガク製ＲＩＮＴ−ＴＴＲIII、線
源ＣｕＫα）による粉末Ｘ線回折測定を行い、（１１１）面のピークから結晶子径を算出した。
（チタン酸バリウムの熱分析）
チタン酸バリウム粉体について、熱分析装置（エスアイアイ・ナノ テクノロジー（株）製ＴＧ／ＤＴＡ６３００）を用いて、３０〜１３００℃の測定範囲において大気雰囲気中、１０℃／分で昇温させて、重量減少を測定した。
(Crystal structure of hydrous titanium oxide)
The crystal structure was confirmed from diffraction data obtained by a powder X-ray diffractometer of hydrous titanium oxide powder (RINT-TTRIII, manufactured by Rigaku Corporation, radiation source CuKα).
(BET specific surface area of hydrous titanium oxide powder and barium titanate powder)
The BET specific surface areas of the hydrous titanium oxide powder and the barium titanate powder were measured using a fully automatic specific surface area measuring device (HM1220 manufactured by Mountec Co., Ltd.). Hydrous titanium oxide was degassed at 120 ° C. and barium titanate at 205 ° C. for 30 minutes, and then measured by the BET one-point method.
(BET equivalent diameter of barium titanate powder)
The BET equivalent diameter of the barium titanate powder was calculated according to the conversion formula described above using the BET specific surface area of the barium titanate with the density of barium titanate being 6.0 g / cm 3 .
(Crystallite diameter of barium titanate)
Powder X-ray diffraction measurement was performed using a barium titanate powder X-ray diffractometer (RINT-TTRIII manufactured by Rigaku Corporation, radiation source CuKα), and the crystallite diameter was calculated from the peak on the (111) plane.
(Thermal analysis of barium titanate)
About barium titanate powder, using a thermal analyzer (TG / DTA6300 manufactured by SII Nano Technology Co., Ltd.), in a measurement range of 30 to 1300 ° C, the temperature was raised at 10 ° C / min, Weight loss was measured.
表２に示すように、本発明によって得られたチタン酸バリウム粉体は、ＢＥＴ比表面積が７０〜１５０ｍ2／ｇの範囲にあると共に、（１１１）面の結晶子径ｃのＢＥＴ換算径Ｄに対する比率ｃ／Ｄで表される合成度が０．８０〜１．５０の範囲にあり、特に、ＢＥＴ比表面積が４００〜５００ｍ2／ｇの範囲にある前記含水酸化チタンを用いることによって、ＢＥＴ比表面積が１００ｍ2／ｇ以上、即ち、ＢＥＴ換算径が１０ｎｍ未満のシングルナノサイズのチタン酸バリウム粉体を得ることができる。かくして、本発明によれば、未反応物の少ない高純度で微細なチタン酸バリウム粉体を得ることができる。 As shown in Table 2, the barium titanate powder obtained by the present invention has a BET specific surface area in the range of 70 to 150 m 2 / g and a BET equivalent diameter D of the crystallite diameter c on the (111) plane. By using the hydrous titanium oxide having a degree of synthesis represented by a ratio c / D to 0.80 to 1.50, in particular, a BET specific surface area in the range of 400 to 500 m 2 / g, A single nano-sized barium titanate powder having a specific surface area of 100 m 2 / g or more, that is, a BET equivalent diameter of less than 10 nm can be obtained. Thus, according to the present invention, a high-purity and fine barium titanate powder with little unreacted material can be obtained.
更に、本発明によるチタン酸バリウム粉体は、その粉末Ｘ線回折パターンを図１に示すように、チタン酸バリウム単相であり、比較例５のように炭酸バリウム由来の異相ピークはみられない。図２に示す熱重量分析の結果においても、本発明によるチタン酸バリウムは強熱減量が小さいことから、未反応物が少なく、高純度であることが示される。また、図３に熱収縮挙動の結果を示すように、高温度における収縮率が小さい。 Further, the barium titanate powder according to the present invention is a single phase of barium titanate as shown in FIG. 1 in the powder X-ray diffraction pattern, and no different phase peak derived from barium carbonate as in Comparative Example 5 is observed. . The results of thermogravimetric analysis shown in FIG. 2 also show that barium titanate according to the present invention has a low ignition loss, so that there are few unreacted substances and high purity. Further, as shown in FIG. 3 showing the result of the heat shrinkage behavior, the shrinkage rate at a high temperature is small.
図４に示す透過型電子顕微鏡写真にみられるように、本発明によるチタン酸バリウム粒子は、格子縞が一定の方向に揃っているので、単結晶粒子であることが示される。 As can be seen in the transmission electron micrograph shown in FIG. 4, the barium titanate particles according to the present invention are single crystal particles because the lattice fringes are aligned in a certain direction.
従って、本発明によるチタン酸バリウム粉体は、ＭＬＣＣ用ペーストの添加剤等に用いるときに焼結時のクラック等を防止することができ、薄層化に対応したＭＬＣＣの製造に好適に用いることができる。
Therefore, the barium titanate powder according to the present invention can prevent cracks during sintering when used as an additive or the like for MLCC paste, and is preferably used for the production of MLCCs corresponding to thinning. Can do.
Claims (4)
ある請求項１に記載のチタン酸バリウム粉体の製造方法。 The method for producing a barium titanate powder according to claim 1, wherein the hydrous titanium oxide has a BET specific surface area in the range of 400 to 500 m 2 / g.
The barium titanate powder according to claim 3, wherein the BET specific surface area is in the range of 100 to 150 m 2 / g, and the ratio c / D is in the range of 1.00 to 1.40.
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