Optimization of preparation conditions of highly textured piezoelectric (Bi_0.5K_0.5)TiO₃ ceramics

Layered titanate H_1.08Ti_1.73O₄·nH₂O (HTO) particles with plate-like morphology were used as a template for the fabrication of grain-oriented bismuth potassium titanate [(Bi_0.5K_0.5)TiO₃, or BKT] ceramics by a reactive-templated grain growth method. Single perovskite-phase textured BKT ceramics were successfully fabricated with optimizing the preparation conditions such as mixing procedure of matrix and template particles with a binder solution, temperature programs for binder removal and sintering, and sintering conditions. Microstructure evaluation suggested that the sintering with or without weight-pressing and a temperature program used could significantly affect the degree of texture development. The debinding and sintering with weight-pressing helped on the proper alignment of oriented particles and/or grains along with promoting the growth of the oriented plate-like BKT particles, formed by an in situ topotactic transformation reaction of plate-like HTO templates, resulting in a high degree of orientation. Using optimum preparation conditions, single perovskite-phase BKT ceramics with grain-orientation over 85% were successfully fabricated for the first time via a conventional sintering method.