Sakai Chemical Industry Co., Ltd.

National Institute for Research in Inorganic Materials

Hajime Uno

Kazunobu Abe

Shinichi Shirasaki

Yasuhiko Terada

Seiji Matsumoto

Yasuo Araki

Shigeharu Higuchi

A process for producing a powder material for niobium-containing lead perovskite ceramics represented by the general formula:

Process for producing powder material for lead perovskite ceramic

A process for producing a peroxoniobic acid sol which comprises: adding a strong acid, hydrogen peroxide and water to at least one niobium compound selected from the group consisting of niobium hydroxide, niobium oxide and niobium pentachloride to provide an aqueous solution of peroxoniobic acid; and then maintaining the aqueous solution at a temperature of 5.degree.-50.degree. C.

Process for producing peroxoniobic acid sol

A method of producing cobalt-modified magnetic particles is provided. The method comprises heating an aqueous suspension of ferric hydroxide at temperatures of 100.degree.-250.degree. C. at an alkaline pH in the presence of a water soluble organic or inorganic compound capable of forming complexes with iron as a growth regulating agent, and preferably also in the presence of .alpha.-ferric oxide seed crystals of minor axes not larger than 0.4 microns in average in amounts of 0.1-25 mole % in terms of the Fe content thereof in relation to the ferric hydroxide, converting the obtained .alpha.-ferric oxide into .gamma.-ferric oxide by reduction thereof followed by oxidation, maintaining an aqueous suspension of the .gamma.-ferric oxide at temperatures of 30.degree.-50.degree. C. at an alkaline pH in the presence of ferrous hydroxide and cobaltous hydroxide in amounts of 0.5-50 mole %, respectively, in relation to the Fe content of the .gamma.-ferric oxide in the suspension for a length of time sufficient to modify the .gamma.-ferric oxide particles.

Method of producing cobalt-modified magnetic particles

Growing community of inventors

Sakai, Japan

Hajime Uno