Structure and Ferroelectric Properties of Dense Nanocrystalline BaTiO3 Ceramics Prepared by High Pressure Sintering Method

Dense nanocrystalline BaTiO3 ceramics with a grain size of 50 nm were prepared under 6 GPa at 1 000 ℃ using a high pressure sintering method. The sintered bulk is uniform and the relative density is above 97%. We annealed the ceramic samples in oxygen to eliminate the oxygen vacancies caused by high pressure. After anneal, several broadened peaks were observed through dielectric measurements. However, these peaks are very different from those of coarser-grained ceramics. The observation of polarization hysteresis loop provides the solid evidence of ferroelectricity in these nano-sized BaTiO3 ceramics. It is believed that the absence of 90 domains and the existence of depolarization field caused by nonferroelectric grain boundaries contribute to the slim loop.