Fabrication of Textured Bismuth Sodium Titanate Using Excess Bismuth Oxide

Bi0.5Na0.5TiO3 (BNT) bulk ceramics with a preferred orientation (texture) were prepared by the reactive-templated grain growth method using platelike Bi4Ti3O12 (BiT) particles as templates for BNT. The texture did not develop extensively in stoichiometric BNT, but the addition of excess Bi2O3 to BNT enhanced the texture development. The role of excess Bi2O3 was examined. The calcined compacts were composed of matrix grains with random orientation and -oriented grains transformed from aligned BiT particles, and texture developed by the preferential growth of oriented grains at the expense of matrix grains. In stoichiometric BNT, the growth rate of matrix grains was high and the conditions for the preferential growth of the oriented grains were disrupted. Excess Bi2O3 reduced grain growth rate, and the conditions for preferential growth were maintained, resulting in the development of highly textured BNT. The resultant textured BNT ceramic exhibited 70% higher piezoelectric d 31 and electromechanical k p coefficients than nontextured BNT.