Formation of Homo-Template Grains in Bi0.5Na0.5TiO3 Prepared by the Reactive-Templated Grain Growth Process

The effects of chemical composition on texture development have been examined for Bi0.5Na0.5TiO3 prepared by the reactive-templated grain growth method, using stoichiometric, Na-excess, and Na-deficient specimens. The highly textured material is obtained by heating the stoichiometric specimen at about 1100 degrees C. Texture development is enhanced in the Na-excess specimen, and the highly textured specimen is hardly obtained for the Na-deficient specimen. The chemical composition affects the formation and growth stages of homo-template grains. Large homo-template grains form in the Na-excess specimen and grow at the expense of small matrix grains. These conditions of the preferential growth of homo-template grains are lost in the Na-deficient specimen because of the small size of homo-template grains and a high growth rate of matrix grains. The dependence of microstructure development on chemical composition is discussed based on the structure of the grain surface on an atomic scale.