Pressure and temperature dependence of the elastic constants of LiBr and LiCI

Abstract

Measurements of the pressure and temperature dependence of the second-order elastic constants of LiBr and LiCl single crystals have been made by the ultrasonic interferometric technique at temperatures from 220 to 340°K, and pressures up to 3.5 kbar. The adiabatic elastic constants (in units of 1011 dyn/cm2) and the isothermal pressure derivative of the adiabatic constants (unitless) at 295°K are as follows (where C00=(1/2)[C11 + C12 + 2C44]): For LiBr, C11 = 3.959, C44 = 1.909, C00 = 4.843, dC11/dP = 10.42, dC44/dP = 1.67, dC00/dP = 8.27. For LiCl, C11 = 4.963, C44 = 2.503, C00 = 6.124, dC11/dP = 10.42, dC44/dP = 1.70, dC00dP = 8.34. The three measured quantities C11, C44, and C00 are given, respectively by ρν112, ρν442, and ρν002, where ρ is the density and the v's are the sound velocities at a specific pressure and temperature. The Deybe temperatures are calculated from the second-order elastic constants at four temperatures on the interval 220–340°K.