Theoretical Model for Explaining the Ferroelectric Effect in Barium Titanate

In order to explain the properties of a barium titanate single domain crystal, a previous theory of the ferroelectric effect in rochelle salt has been extended to the three-dimensional structure of barium titanate. This involves six equilibrium positions and results in significant differences from the single bond type of structure of rochelle salt. The theoretical features considered are a calculation of the spontaneous polarization as a function of temperature, the dielectric constants along the a=y and c=z axes as a function of temperature, the relaxation of the dielectric constant at high frequencies, and the hysteresis loops. All of these features are explained by the three-dimensional model considered here.