Temperature dependent acoustical characterization of alkaline earth monochalcogenides in B1 and B2 phase

The Born model of ionic solids has been applied to study the temperature dependence of acoustical dissipation due to phonon-phonon interaction, thermo-elastic mechanism and dislocation damping due to screw and edge dislocations in alkaline earth chalcogenides viz. calcium and barium chalcogenides [CaX and BaX; X=S, Se and Te] in FCC as well as BCC phases, in the wide temperature range (50-500 K); for longitudinal and shear modes of propagation along 〈1 0 0〉, 〈1 1 0〉 and 〈1 1 1〉 directions and for shear modes with different polarizations. Electrostatic and short-range repulsive potentials have been used for evaluating second and third order elastic constants at required temperature, which in turn have been used to obtain acoustical dissipation and related parameters at different temperatures. Hardness parameter, lattice constants and experimental values of second order elastic constants have been used as input parameters. Results have been discussed and temperature variation of acoustical dissipation has been found to exhibit exponential behaviour.