Abstract
We developed a novel processing method, the reactive templated grain growth (RTGG), for the fabrication of highly textured polycrystalline ceramics with a regular perovskite-type structure. Plate-like particles with a layered perovskite-type structure were used as a reactive template, of which the preferred orientation was preserved in the in-situ formed regular perovskite-type polycrystals after heat-treatment. The textured ceramics exhibited a brick-wall-like microstructure and enhanced piezoelectric properties. The mechanism of conversion from a layered perovskite-type template into a regular perovskite-type product was rather topotactic. Furthermore, the RTGG processing was also applied to the fabrication of more complex bismuth layer-structured (BLS) ceramics with a preferred {001} orientation. The textured BLS ceramics exhibited 3–4 times as high piezoelectric coefficients and electromechanical coupling factors as the conventionally sintered BLS ceramics of the same compositions. The textured BLS ceramics showed a layered-slate-like microstructure. The unique microstructures of the two types of textured ceramics ({100}-oriented regular perovskite and {001}-oriented BLS) reflected anisotropy in terms of the surface energy for the crystal structures of regular perovskite and BLS.
