Investigation of ferroelectric properties on nanocrystalline barium titanate ceramics

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 120°C 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 internal 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. © 2007 Higher Education Press and Springer-Verlag.