Theoretical Analysis of Acoustic Attenuation and Nonlinearity in Barium Monochalcogenides in B2 Phase

Temperature dependence of ultrasonic attenuation due to phonon-phonon interaction and thermoelastic loss have been studied in (CsCl-type) barium monochalcogenides (BaX, X= S, Se, Te), in the temperature range 50–500 K; for longitudinal and shear modes of propagation along 100 , 110 and 111 directions. Second and third order elastic constants have been evaluated using electrostatic and Born repulsive potentials and taking interactions up to next nearest neighbours. Gruneisen parameters, nonlinearity constants, nonlinearity constants ratios and viscous drag due to screw and edge dislocations have also been evaluated for longitudinal and shear waves at 300 K. In the present investigation, it has been found that phonon-phonon interaction is the dominant cause for ultrasonic attenuation. The possible implications of the results have been discussed.