Acoustical Dissipation in Mixed Crystalline KBr-NaBr System

Ultrasonic attenuation due to phonon-phonon interaction and thermoelastic loss has been studied from 50K to 600K in (KBr)_x (NaBr)_1-x mixed crystalline system. Starting from nearest-neighbour distance and repulsive parameters as input data, elastic constant data have been obtained at different temperatures. These values have been utilized to evaluate Gruneisen parameters, non-linearity coupling constants and sound attenuation due to phonon-phonon (p-p) interaction and thermoelastic loss, along <100> crystallographic direction of propagation for longitudinal and Shear waves. Dislocation damping due to screw and edge dislocations has also been studied. Temperature variation of (α/f²) has been found similar to dielectric crystals. Results have been discussed.