Structure and Properties of (Ba,Ca) TiO3 Ceramics Prepared Using (Ba,Ca)TiO3 Ceramics I, Crystallographic and Microstructural Studies |
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Authors: | Vidya S. Tiwari Neelam Singh Dhananjai Pandey |
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Affiliation: | School of Materials Science and Technology, Banaras Hindu University, Varanasi, 221 005, India |
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Abstract: | Ba1–xCaxTiO3 powders have been prepared using a novel route involving solid-state reaction in a mixture of Ba1–xCaxCO3 and TiO2. The Ba1–xCaxCO3 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 TiO2. The compositional homogeneity of Ba1–xCaxTiO3 powder prepared by such a semiwet route is compared with those prepared by the conventional dry route, involving thermochemical reaction in a mixture of BaCO3, CaCO3, and TiO2, 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 Ba1–xCaxTiO3 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. |
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