| abstract |
An aqueous solution of a metal salt to an alkaline aqueous solution to forma hydroxide or a hydrate of a metal, and the hydroxide or hydrate of the metal is heated at a temperature of 110 to 300° C. in the presence of water. Then, the hydroxide or hydrate of the metal is filtered and dried and then further heated at a temperature of 300 to 1200° C. in an air to form oxide particles such as the particles of cerium oxide, zirconium oxide, aluminum oxide silicon oxide, iron oxide, etc. Thereby the particles of cerium oxide, zirconium oxide, aluminum oxide silicon oxide, iron oxide, etc. having a plate-form shape and a particle size of from 10 nm to 100 nm in the plate direction of the particle are obtained. The non-magnetic particles, in particular, plate-form oxide particles of the present invention have a uniform particle size distribution, are less sintered or agglomerated, and have good crystallinity. |