The lattice theory of the elastic dielectric developed in the preceding paper is applied to the fluorite lattice. Expressions are derived for the third-order elastic constants of the fluorite lattice in Axe's shell model. The values of the third-order elastic constants and the pressure derivatives of the second-order elastic constants are calculated for calcium, strontium, and barium fluorides on the rigid-ion and shell models. In calcium fluoride, the calculated values of the pressure derivatives of the second-order elastic constants are in fair agreement with Wong and Schuele's experimental values. The static dielectric constant and its strain dependence are also calculated for the three fluorides in the shell model.

• Received 27 March 1967

DOI:https://doi.org/10.1103/PhysRev.165.1054