The Adiabatic Elastic Constants of Rock Salt

The velocities of propagation of 10-Mc/sec longitudinal and transverse sound waves in single crystals of rock salt have been measured over the temperature range from 60^∘{}K to 300^∘{}K by means of the ultrasonic pulse method. From these velocities the adiabatic elastic constants have been calculated, with the results that c₁₁=4.828±0.015, c₄₄=1.273±0.005, and c₁₂=1.276±0.025 at 300^∘{}K in units of dyne/cm²×{}10¹¹. The values of these elastic constants extrapolated to absolute zero temperature are in these units, 5.750, 1.327, and 0.986, respectively. The adiabatic compressibility has been calculated from c₁₁ and c₁₂ and is 4.07×{}10^-12 cm²/dyne at 300^∘{}K. The Debye characteristic temperature is computed to be 292.6±{}0.5^∘{}K at $T=0$^∘{}K.