Effect of Grain Size on Phase Transitions and Dielectric Properties of Nano-crystalline Barium Titanate Ceramics

摘要

Barium titanate (BaTiO_3) ceramics with grain size varied from 1000 to 8 nm were prepared by two step sintering method (TSS) and spark plasma sintering (SPS), respectively. Mixture structures of BaTiO_3 ceramics were proved by in-situ temperature high resolution x-ray diffraction. Multiple ferroelectric domains present in nano-crystalline BaTiO_3 ceramics were observed by transmission electron microscope. The evolution of phase transitions supported the existence of intrinsic mechanism. Dielectric loss of fine grain size BaTiO_3 was higher than coarse grain size during Curie phase transition due to diffuse phase transition and grain boundary effects.