PURPOSE: To obtain the title structure with density close to the theoretical value by calcining a mixed raw material composition which is prepared by adding to a suspension of oxide ceramic raw material powder an organic compound containing the constituent elements for said raw material to effect coating the surface of the raw material powder with highly active fine particles.

CONSTITUTION: Firstly, oxide ceramic powder is suspended in an organic solvent into a suspension. Thence, a liquid organic compound or a solution of this compound containing an element same as or different from the constituent element for said oxide is admixed with the above suspension followed by distillation. Thus, fine particles of said organic compound are deposited on the surface of the ceramic powder. The mixed raw material composition thus obtained is then formed and calcined.