Process for producing columbite-type niobate and process for producing perovskite-type compound therefrom

摘要

A process for producing a columbite-type niobate and a process for producing a niobium-containing lead-type perovskite compound using the columbite-type niobate. A precursor slurry of a columbite compound composed of a fresh niobium hydroxide, a metal acetate and ammonium aqueous solution is spray-dried, and is calcined at 500 DEG C. or higher to obtain a crystalline columbite-type compound having grain sizes of 1 mu m or smaller to which was then mixed a lead component. The mixture is calcined, pulverized and is sintered at a temperature of 800 DEG to 1100 DEG C. to synthesize a highly dielectric material of a niobium-containing lead-type composite perovskite. The precursor of columbite is calcined at 500 DEG to 1100 DEG C. to obtain fine columbite-type niobate crystals of grain sizes of 1 mu m or smaller. A lead-type perovskite compound using the above crystals can be sintered at a temperature of as low as 950 DEG C. or lower, and the sintered product thereof has a homogeneous and fine texture and excellent dielectric properties that could not be obtained by the conventional solid-phase process.