论文部分内容阅读
Dense nanocrystalline BaTiO3(BT) ceramics with 50 nm average grain size obtained by spark plasma sintering were investigated.The dielectric data showed a ferropara phase transition with a maximum permittivity of 1,602 at 1 20℃ and at 1 kHZ.The polarization reversal characteristics were measured,and the typical piezoelectric hysteresis loop was recorded.The asymmetry of permanent polarization and coercive field in polarization-electric field curves were obtained and attributed to the existence of an intal electric field.The present results provide experimental evidence,indicating that if a critical grain size exists for ferroelectricity,then it is less than 50 nm for polycrystalline BT ceramics.