Elastic constants of cubic lead fluoride from 300 to 850 K

Measurements of ultrasonic velocity in single-crystal cubic PbF₂ have been made over a temperature range from 300 to 850 K. Values of the three independent, adiabatic elastic constants over this temperature range are obtained from C₁₁, (C₁₁+C₁₂+2C₄₄)2, (C₁₁-C₁₂)2, and C₄₄. The results are anomalous at the Faraday temperature of 711 K for PbF₂, which is well below its melting temperature of 1158 K. A large decrease in the elastic constant C₁₁ and much smaller decrease in C₁₂ and C₄₄ are observed near 711 K in addition to the nearly linear decrease in the elastic constants with temperature.