Temperature Dependence of the Elastic Constants of Calcite between 160° and 300°K

Variation in the elastic constants of calcite in the range of 160° to 300°K has been investigated by the ultrasonic phase-comparison method. The values of the elastic constants and the elastic compliances of calcite vary linearly over the temperature range, and thus are in disagreement with the nonlinear behavior of the elastic compliances of calcite between 90° and 273°K reported by Ramamurthy and Reddy (R and R). It is suggested that this discrepancy in the two results is likely to be due to the inconsistent vibrational data of R and R and the impossible behavior of the compressibility of calcite with temperature as obtained from their estimates of the elastic compliance values of calcite. The present investigation also indicates that the variation in the volume compressibility of calcite is primarily due to the variation in linear compressibility of calcite perpendicular to its optic axis, and the temperature dependence of all the elastic constants except for C44 are explicitly due to the temperature change.