PURPOSE: To obtain a transparent yttria sol having a small average grain diameter and a high grain concn. and excellent in economical stability by allowing yttrium acetate to react with an alkaline substance, cleaning the produced yttria sol with an ultrafilter membrane and then concentrating the sol.
CONSTITUTION: An aq. soln. of yttrium acetate is heated and agitated, and an alkaline substance is gradually added to allow the yttrium acetate to react with the alkaline substance. The produced yttria sol is cleaned by an ultrafilter membrane and then concentrated to obtain the desired transparent yttria sol contg. the grains having 10-80 average diameter. Although the concn. of the yttrium acetate in the soln. to be used is relatively low since the solubility of the yttrium acetate in pure water is low, the concn. can be increased to 0.4mol/l by heating the soln.
HATA KAZUO
TAKAHASHI TSUKASA
