Structure and Properties of (Ba,Ca) TiO 3 Ceramics Prepared Using (Ba,Ca)TiO 3 Ceramics I, Crystallographic and Microstructural Studies

Ba 1–x Ca x TiO 3 powders have been prepared using a novel route involving solid‐state reaction in a mixture of Ba 1–x Ca x CO 3 and TiO 2 . The Ba 1–x Ca x CO 3 precursors used in this method were prepared by a chemical coprecipitation route to ensure a uniform supply of Ba and Ca ions during thermochemical reaction with TiO 2 . The compositional homogeneity of Ba 1–x Ca x TiO 3 powder prepared by such a semiwet route is compared with those prepared by the conventional dry route, involving thermochemical reaction in a mixture of BaCO 3 , CaCO 3 , and TiO 2 , using principles of X‐ray line broadening. It is shown that the powders obtained by the semiwet route possess better compositional homogeneity, over a length scale of 1800 Å corresponding to the coherently scattering domain size, than those prepared by the conventional dry route. Microstructural studies have revealed grain sizes of the order of 1 μm and several micrometers, respectively, for ceramics prepared by the semiwet and conventional dry routes. The solid solubility limit of Ca in Ba 1–x Ca x TiO 3 ceramics fired at 1300°C is 16 mol% for samples prepared by the semiwet route while conventionally processed ceramics had a Ca solid Solubility limit of 12 mol% at the same temperature.