Determination of the Electro-Optical Coefficients of Barium Titanate

Within the framework of the theory of thermodynamics, a method for determining the electro-optical coefficients is proposed. It is shown that for all ferroelectrics the symmetry of which admits a diagonal susceptibility, the ratio of some electro-optical coefficients is expressed in terms of the ratio of susceptibilities. For barium titanate, the dependence of the electrooptical coefficients on the electric field has been revealed and studied. It is shown that large values of the electro-optical coefficients of barium titanate are associated with a nonlinear dependence of the dielectric susceptibility on the electric field.