Grain growth kinetics of textured 0.92Na0.5Bi0.5TiO3—0.08BaTiO3 ceramics by tape casting with Bi2.5Na3.5Nb5O18 templates

Abstract

Plate-like Bi2.5Na3.5Nb5O18 particles were used as templates to fabricate grain-oriented Na0.5Bi0.5TiO3—BaTiO3 (NBTBT) ceramics by reactive-templated grain growth. The effects of sintering conditions on the grain orientation and microstructure of the textured NBTBT ceramics were investigated, and the kinetic mechanism of grain growth is discussed. The results show that textured ceramics were successfully obtained with orientation factor more than 0.6. NBTBT specimens are composed of strip-like grains and equiaxed shaped grains. The textured ceramics have a microstructure with strip-like grains aligning in the direction parallel to the casting plane and exhibit an {h00} preferred orientation. The degree of grain orientation increases initially, then decreases with increasing sintering temperature and soaking time. The maximum texture fraction is 0.69 when sintered at 1185 °C for 6 h. The kinetic exponent n and activation energy Q of the two types of grain in textured NBTBT ceramics were calculated. The results show that the grain growth mechanism of oriented grains is controlled not only by grain lattice diffusion, but also by grain boundary diffusion. The grain growth mechanism of matrix grains is mainly controlled by the grain boundary curvature.