| 摘要 |
A process for the preparation of crystalline perovskite powders consisting essentially of primary particles uniform in nanometer or micrometer size and uniform and near spherical shape and of narrow size distribution, of the general formula Ax(BO3)y, wherein cation A is at least one metal selected from the group comprising Li<+>, Na<+>, K<+>, Mg<2><+>, Ca<2><+>, Sr<2><+>, Ba<2><+> and La<3><+> and B in the anion (BO3) is at least one metal selected from the group consisting of Ti<4><+>, Zr<4><+>, Sn<4><+>, Hf<4><+>, Nb<5><+> and Ta<5><+>, x is equal to the valence of the anion (BO3) and y is equal to the valence of cation (A), comprising contacting, under stirring, an aqueous solution (I) containing inorganic or organic salts or organometallic compounds of at least one metal A and of at least one metal B, the ratio (A)/(B) being around the stoichiometric value corresponding to the above general formula, with an aqueous basic solution (II) containing an inorganic or organic base in an amount at least above the stoichiometric amount corresponding to the above general formula, preheated to 70 DEG -100 DEG C, and performing the process at temperatures of from 70 DEG to 100 DEG C while maintaining the reaction mixture at constant OH<-> concentration. |
