High frequency acoustic attenuations in dielectric crystals

High frequency acoustic attenuations have been calculated for dielectric crystals of Potassium Halides (KCl, KBr and KI) for a wide range of temperature from 100 – 500 K. Second order and Third order elastic constants of these dielectric crystals are used to obtain the temperature dependent values of longitudinal wave velocity (VL), shear wave velocity (VS), non-linearity parameter DL and DS, thermal relaxation time τ, energy density E0, and using them the attenuation coefficients are calculated. Attenuation in dielectric crystal is found to be temperature dependent. Attenuation of high frequency acoustic waves is found to have maximum value for KI crystal and minimum value for KCl crystal, while, for KBr crystal it is intermediate between the above two values. Phonon-Phonon interaction is the most prominent cause of the acoustic attenuation of the high frequency waves propagating through the crystals. Shear waves are more attenuated as compared to longitudinal waves.