Critical thickness for ferroelectricity of BaTiO3 by first-principles calculations -: art. no. 222901

The critical thickness for ferroelectricity of a BaTiO3 film was determined by the first-principles discrete variational-X alpha molecular orbital method and population analysis. Under the assumption that most ferroelectric perovskite oxides are predominantly ionic, a series of model clusters were developed for a BaTiO3 particle consisting of a Ba8Ti7O6 cluster constructed on the basis of the crystal structure of BaTiO3 phase and point charges surrounding the Ba8Ti7O6 cluster. The size of the model cluster was exactly defined by the size of a three-dimensional point-charge array. By comparing the dependence of the net charge of Ba, Ti, and O ions and of the overlap population between Ti 3d and O 2p orbitals on particle thickness in tetragonal and cubic BaTiO3 particles, the critical thickness for ferroelectricity was calculated to be about 12 nm for a BaTiO3 particle with a basal area of 20x20 nm. (c) 2005 American Institute of Physics.