Temperature variations of the elastic constants ofCaF2andSrF2crystals

We have investigated the temperature variations of the second-order elastic constants of ${\mathrm{CaF}}_2$ and ${\mathrm{SrF}}_2$ crystals by means of a three-body-interaction potential model which earlier has successfully described such variations exhibited by the other members of the fluorite family [Phys. Rev. B 39, 13493 (1989)]. Our results, obtained from the three-body-interaction potential model, have shown reasonably good agreement with their experimental neutron-scattering data. On the basis of these successful descriptions, we have concluded that three-body interactions and lattice anharmonicity play an important role in revealing the anomalous behavior and temperature variations of the elastic constants of fluorites.