PROCESS FOR PREPARING PRECIPITATE OF METAL OXIDE

摘要

A process for preparing a precipitate of a metal oxide, which comprises adding a fluoride ion scavenger to an aqueous or hydrofluoric acid solution of a fluorocomplex compound and/or a fluoride of a rare earth element to form a precipitate of a rare earth oxide or a solid solution composed mainly of the oxide; and a process for preparing a precipitate of a metal oxide, which comprises adding a seed crystal and a fluoride ion scavenger to an aqueous or hydrofluoric acid solution of a fluorometal complex compound and/or a metal fluoride of zirconium and/or hafnium to form a crystal of the metal oxide or a solid solution composed mainly of the metal oxide. The process is suitable for forming a precipitate of a rare earth oxide and a crystalline precipitate of zirconium oxide and/or hafnium oxide, particularly for forming a precipitate in the form of a thin film of a metal oxide or the like on the surface of a substrate having a large area or a complicate shape by using a simple device without need of the step of heating for crystallization.