SYNTHESIS OF COLUMBITE-TYPE NIOBIC ACID SALT AND SYNTHESIS OF PEROVSKITE-TYPE COMPOUND USING THE SALT

摘要

PURPOSE: To synthesize a uniform columbite-type niobic acid salt having high purity by mixing freshly prepared aqueous slurry of niobium hydroxide with a metal acetate and ammonia water, spray-drying the mixture and calcining the dried product and to obtain a niobium-containing lead-based perovskite-type compound having uniform composition, high purity and fine particle size by mixing the niobic acid salt with lead oxide and calcining the mixture at a low temperature. ;CONSTITUTION: Niobium hydroxide is dissolved in oxalic acid and ammonia water is added to the solution to form precipitate. The freshly prepared aqueous slurry of niobium hydroxide is mixed with stoichiometric amount of a metal acetate (metal is Mg, Ca, Zn, Ni, Co, Fe, Mn, Cr, Cu or In) based on the niobium hydroxide and ammonia water and the mixture is dried by spray-drying or freeze-drying to form powder, which is calcined at 500-1100°C to obtain a columbite-type niobic acid salt. The salt is mixed with a lead oxide at stoichiometric ratio and calcined at 600-700°C to obtain a niobium-containing lead-based perovskite-type compound [e.g. Pb(Mg.Nb)O₃].;COPYRIGHT: (C)1994,JPO&Japio