PURPOSE: To improve the purity of a metal oxide powder to be synthesized at the time of synthesizing the powder in a reactor by washing the metallic material with high-purity water to remove the halogen elements contained in the material.
CONSTITUTION: A metal powder and a carrier gas are supplied to a reaction vessel filled with an oxidizing atmosphere to burn the metal powder in the vessel, and a metal oxide powder is synthesized. In this case, a lumpy or powdery material for the metal powder is washed with high-purity water to control the fluoride ion concn. in the extraction water to ≤2ppm and the chloride ion concn. to ≤1ppm. The metal powder is adjusted to a specified particle size, heat-treated and used as the metallic material. As a result, a high-purity metal oxide powder freed of the halogen elements such as fluorine and chlorine is obtained.
TANAKA HIDEJI
ABE SAN
SHINETSU CHEMICAL CO