Acoustical investigation of lead chalcogenides

Temperature dependence of ultrasonic attenuation due to phonon-phonon interaction and thermo-elastic loss have been studied in NaCl-type lead monochalcogenides (PbS, PbSe and PbTe) in the temperature range 100-500 K for longitudinal and shear modes of propagation along <1 0 0>, <1 1 0> and <1 1 1> directions. Second and third order elastic constants have been evaluated using electrostatic and Boern repulsive potentials and taking interactions up to next nearest neighbours. These values have been utilized to obtain attenuation coefficient for lead compounds. In the present investigation, it has been found that phonon-phonon (p-p) interaction is the dominant cause for ultrasonic attenuation. The possible implications of the results have been discussed.