Theory of the Dielectric Constants of Barium Titanate

Abstract

Clamped dielectric constants of barium titanate crystal in tetragonal and cubic phases are calculated based upon a molecular model. The mechanism of anisotropy of the dielectric constants in tetragonal phase can be explained by using this model. In this article the shift of only the Ti ions is taken into account. The results of the calculation can explain the origin of the dielectric anomaly of barium titanate to some extent. A quantitative analysis of the mechanism of the transitions between cubic, tetragonal and orthorhombic phases is also attempted.