Ferroelectric properties study for nanocgrain barium titanate ceramics

Dense nanocrystalline BaTiO3 ceramics with 50 nm average grain size obtained by spark plasma sintering were investigated. The dielectric data show a ferro-para phase transition with a maximum permittivity of 1602 at 120 degrees C and at 1 kHz. The polarization-reversal characteristics and the local ferroelectric switching behavior were measured; the typical piezoelectric hysteresis loops were recorded. The asymmetry of permanent polarization and coercive field in polarization-electric field curves were obtained and attributed to the existence of internal electric field. The present results provide experimental evidence, indicating that if a critical grain size exists for ferroelectricity it is less than 50 nm for polycrystalline BaTiO3 ceramics. (C) 2010 Elsevier B.V. All rights reserved.