Phase diagram and ferroelectric behaviors of BaTiO3 nanowires

A modified Landau-Ginzburg-Devonshire theory is developed to investigate the "diameter-temperature" phase diagram and the ferroelectric behaviors of BaTiO3 nanowires. Four phases, such as the Cubic phase, the Tetragonallike phase, the Orthorhombic phase, and the Monoclinic phase, are obtained. The ferroelectric phase transition temperatures are all depressed as the diameter decreases. A temperature-dependent critical diameter below which the polarization disappears is 0.8 nm at 0 K. Moreover, the magnitude and the direction of the polarization are strongly dependent on the diameter as well as the dielectric behaviors. Therefore, it can generate a specific direction of the polarization by controlling the diameter of the nanowires which may optimize the physical properties. (C) 2011 American Institute of Physics. [doi:10.1063/1.3559810]