Texture development and dielectric relaxor behavior of _0.80Na_0.5Bi_0.5TiO₃-0.20K_0.5Bi_0.5TiO₃ ceramics templated by plate-like NaNbO3 particles

Plate-like NaNbO₃ particles were used as templates to fabricate grain-oriented 0.96(0.8Na_0.5Bi_0.5TiO₃-0.2K_0.5Bi_0.5TiO₃)-0.04NaNbO₃ (NKBT) ceramics. The effects of the sintering temperature and the soaking time on the grain orientation and the microstructure of the textured NKBT ceramics were investigated, and the dielectric relaxor behavior is discussed. The results show that textured ceramics were successfully obtained with orientation factor more than 0.8. The textured ceramics have a microstructure with strip-like grains aligning in the direction parallel to the casting plane. The degree of grain orientation increases initially, then decreases with increasing sintering temperature, and increases continuously with increasing soaking time. The textured NKBT ceramics shows obvious dielectric relaxor characteristics which can be well explained by microdomain-macrodomain transition theory with calculating criterion K. The results show that formation of texture is beneficial to microdomain-macrodomain transition, which lead to weaken relaxor behavior and raise the dielectric constant at T_tr.