Texture Formation in Barium Titanate-base Ceramics by Reactive-Templated

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Crystallographically textured BaTiO_3 with <111>-and <100>-orientation was prepared by reactive-tempated grain growth (RTGG) method, using platelike Ba_6Ti_<17>O_<40> (B6T17) and Bi_4Ti_3O_<12> (BiT) particles as reactive-templates for <111>-and <100>-orientation, respectively. These particles were mixed with BaCO_3 powder, and tape-cast to prepare green compacts with the aligned platelike particles. Calcination of these compacts in air and vacuum for <111>-and <100>-orientation, respectively, formed oriented BaTiO_3 particles. Textured ceramics were obtained by sintering the calcined compacts between 1300゜ and 1400℃, but the sintered densities were between 8O and 90% of theoretical. Large voids formed between platelike particles in the green compacts grew to large elongated pores during sintering, and these pores could not be eliminated. To fill the large voids, BaTiO_3 powders with the average particle size between 0.1 and 0.5 μm were added as filler, and the sintered density increased up to 95 and 99%. The efficiency of increasing density was dependent on the particle size. The filler had no deteriorated effect on the texture formation. Thus, dense, highly-textured BaTiO_3 ceramics were prepared, and the effects of processing parameters on the density and orientation were examined.