| 摘要 |
1,157,383. Alkaline earth metal zirconates and titanates. NATIONAL LEAD CO. 7 Sept., 1967 [14 Nov., 1966], No. 41037/67. Heading C1A An alkaline earth metal zirconate or titanate is prepared by precipitating an alkaline earth metal carbonate in the presence of an aqueous suspension of ZrO 2 or TiO 2 , separating the mixture of carbonate and oxide, and calcining the mixture. The carbonate may be precipitated at 15-40‹ C. by reation of an alkaline earth metal chloride, acetate, or nitrate with (NH 4 ) 2 CO 3 , Na 2 CO 3 , or K 2 CO 3 . The mixture may be washed, dried at 160‹ C. or below, pulverized, calcined at 800-1200‹ C., and pulverized. The particle size of the starting oxide may be less than 1 Á, and of the product, 0À6-5 Á. In examples, BaTiO 3 , BaZrO 3 , CaTiO 3 , and SrZrO 3 were prepared, but the proportions may be varied, e.g. to give Ba titanate with an excess or deficit of TiO 2 . Mixtures containing ZrO 2 and TiO 2 , and a plurality of alkaline earth metals, may be prepared, e.g. BaCa titanate. The product may be shaped with polyvinyl alcohol and fired at 1200‹ C. to give dielectric bodies. |
