Predicting the domain structures and properties in both bulk single crystal and thin film ferroelectrics using the phase-field approach requires the knowledge of fundamental mechanical, electrical, and electromechanical coupling properties of a single-domain state. In this work, the elastic properties and structural parameters of cubic single crystals as well as tetragonal, orthorhombic, and rhombohedral BaTiO3 single domain states are obtained using first-principles calculations under the local density approximation. The calculated lattice constants, bulk modulus, and elastic constants are in good agreement with experiments for both the cubic paraelectric phase and the low-temperature ferroelectric phases. Spontaneous polarizations for all three ferroelectric phases and the electrostrictive coefficients of cubic BaTiO3 are also computed using the Berry’s phase approach, and the results agree well with existing experimentally measured values.

Misfit strain dependence of ferroelectric and piezoelectric properties of clamped (001) epitaxial Pb(Zr0.52,Ti0.48)O3 thin films Appl. Phys. Lett. 99, 252904 (2011) Phase transitions in ferroelectric-paraelectric superlattices J. Appl. Phys. 110, 114109 (2011) Dielectric and nonlinear current-voltage characteristics of rare-earth doped CaCu3Ti4O12 ceramics J. Appl. Phys. 110, 094101 (2011) Scanning electro-optic microscopy of ferroelectric domain structure with a near-field fiber probe J. Appl. Phys. 110, 084117 (2011) Ferroelectric domains in epitaxial PbTiO3 films on LaAlO3 substrate investigated by piezoresponse force microscopy and far-infrared reflectance A modified eighth-order Landau potential was proposed for the BaTiO 3 single crystal by taking account into the quantum mechanical effects at low temperature. While all existing thermodynamic potentials for BaTiO 3 fail to accurately describe the pressure dependence of ferroelectric transition temperatures, the temperature and hydrostatic pressure phase diagram constructed using the modified potential shows excellent agreement with experimental measurements by Ishidate, Abe, Takahashi, and Mori ͓Phys. Rev. Lett. 78, 2397 ͑1997͔͒. On the basis of the new proposed Landau potential, we calculated the dielectric coefficients, spontaneous polarizations, temperature-electric field phase diagram, and piezoelectric coefficients, all in good agreement well with existing experimental data.