Theoretical evaluation of the temperature dependence of third order elastic constants and ultrasonic attenuation in NaCl

Abstract

Abstract This paper presents a comprehensive calculation of ultrasonic attenuation in NaCl in the temperature range 80–300 K using the temperature dependent third order elastic constants (TOEC). A method is suggested here to evaluate the temperature dependence of the complete set of TOEC using the measured nonlinearity parameters in combination with the Varshney model for elasticity of alkali halides. Our calculations reproduce the measured combinations of TOEC reasonably well. This set is used to compute the temperature dependence of ultrasonic attenuation for longitudinal and shear waves along the [100] direction and for a longitudinal wave along the [111] direction. The orientation dependence of attenuation is also computed using this set for the [100], [110] and [111] directions. The calculation of attenuation is performed using both Mason's limited mode approach as well as by taking into account the interaction of the sound wave with a much wider spectrum of thermal phonon modes and incorporating the refinements suggested by Merkulov et al . regarding the dependence of Mason's integral on the cutoff frequency supported by the lattice. The results of our refined calculations show better agreement with the experiment than those obtained using Mason's scheme in most cases.