Microstructure development and texture formation in lead-free piezoelectric ceramics prepared by templated grain growth process

Abstract

Templated and reactivelated grain growth is a convenient preparation method for textured ceramics. In this method, green compacts composed of aligned template grains and randomly oriented matrix grains are sintered. The matrix grains must be eliminated to obtain highly textured materials and an understanding of the growth behavior for both template and matrix grains is essential to the design of the conditions for effective elimination of matrix grains. This review paper addresses the microstructure development in BaBi4Ti4O15 and Bi4Ti3O12 prepared by the templated grain growth method and in Bi0.5(Na11-xKx)0.5- TiO3 and K0.5Na0.5NbO3 textured by the reactivelated grain growth method. The grains of these materials are faceted, and critical driving force is required for the growth of faceted grains. It is illustrated that the relative magnitude of the driving force of the template grains and the critical driving force determines the mode of grain growth behavior and the microstructure of the final products. A discussion on the grain growth behavior is presented to give the criteria for designing the preparation conditions.