Material Properties of Barium Titanate Single Crystal from Modified Time-Dependent Devonshire-Ginzburg-Landau Model

We simulated and compared the material properties of barium titanate for five states, namely, (1) the orthorhombic state, (2) the orthorhombic state near the orthorhombic-tetragonal phase boundary, (3) the tetragonal state near the orthorhombic-tetragonal phase boundary, (4) the tetragonal state, and (5) the tetragonal state near the tetragonal-cubic phase boundary by using a modified time-dependent Devonshire-Ginzburg-Landau model. We reproduced reasonable variations in piezoelectric coefficients, dielectric susceptibilities, and elastic compliance constants for the above-mentioned five states, especially for the phase boundary states. Moreover, we simulated the hysteresis curves of the dependence of electric polarization and strain on electric field and the dependence of the hysteresis curves on compressive stress. The obtained simulation results are well explained by the polarization rotation or extension, which is made easy by the free energy flattening induced by temperature or electric field. (C) 2012 The Japan Society of Applied Physics