Sakai Chemical Industry Co., Ltd.

Shinji Ogama

Yukihiro Kuniyoshi

Minoru Yoneda

Kazuhisa Hidaka

Yoshiaki Ikeda

Kazumi Yamanaka

Yuji Baba

Masami Kuwai

Takashi Shikida

The invention provides a method for producing barium titanate powder comprising the steps of: adding an aqueous slurry of anatase hydrous titanium oxide having a BET specific surface area in the range of 200 m/g to 400 m/g and a half width of diffraction peak of (101) plane in the range of 2.3&#xb0; to 5.0&#xb0; as measured by X-ray diffraction to an aqueous solution of barium hydroxide while maintaining the aqueous solution of barium hydroxide at a temperature in the range from 80&#xb0; C. to the boiling point thereof under normal pressure to cause a reaction of the barium hydroxide with the hydrous titanium oxide to provide an aqueous slurry of barium titanate precursor; and subjecting the barium titanate precursor thus obtained to hydrothermal treatment over a period of not less than 24 hours to provide barium titanate particles.

Method for producing barium titanate powder

The invention provides a method for producing barium titanate powder comprising the steps of: adding an aqueous slurry of anatase hydrous titanium oxide having a BET specific surface area in the range of 200 to 400 m/g and a half width of diffraction peak of (101) plane in the range of 2.3&#xb0; to 5.0&#xb0; as measured by X-ray diffraction to an aqueous solution of barium hydroxide while maintaining the aqueous solution of barium hydroxide at a temperature in the range from 80&#xb0; C. to the boiling point thereof under normal pressure to cause a reaction of the barium hydroxide with the hydrous titanium oxide to provide an aqueous slurry of barium titanate precursor; and subjecting the barium titanate precursor thus obtained to hydrothermal treatment over a period of time shorter than 24 hours to provide barium titanate particles.

The invention provides a process for production of powder of perovskite compound which comprises: The process makes it unnecessary to resort to a conventional mechanical crushing means or to make use of impact caused by milling media or airflow, but it makes possible to obtain a powder of perovskite compound which is not contaminated with impurities derived from milling media or chipping particles but has a high purity and a narrow particle size distribution.

Process for production of powder of perovskite compound

The invention provides a process for production of a composition comprising a perovskite structure compound, the process comprising: a first process to heat a hydrous oxide of at least one B group element selected from the group consisting of Ti, Zr, Hf, and Sn at a temperature within a range of 80 to 300&#xb0; C. in the presence of an aqueous medium so as to dehydrate the hydrous oxide; and a second process to heat a reaction product obtained in the first process and a hydroxide of at least one A group element selected from the group consisting of Ba, Sr, Ca, Mg and Pb at a temperature within a range of 100 to 300&#xb0; C. in the presence of an aqueous medium. The process provides a composition comprising an ABOcompound in the form of uniform and fine spherical particles which have an average particle diameter of 1 &#x3bc;m or less, preferably within a range of 0.01 to 0.5 &#x3bc;m, high crystallinity, and a controlled A/B ratio as desired, as well as few internal pores in the crystalline particles.

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Sakai, Japan

Shinji Ogama