ANALYSIS OF ANHARMONIC ELASTIC PROPERTIES OF ANTI-FLUORITE STRUCTURE A(2)MX(6) SINGLE-CRYSTALS

In the present paper an analysis of vibrational anharmonic properties of a number of antifluorite structure crystals [K2SnCl6, K2ReCl6, K2PtBr6, (NH4)(2)SnCl6, (NH4)(2)PtBr6 and (NH4)(2)TeCl6] has been performed in terms of higher order elastic constants and their linear combinations, pressure and temperature derivatives of their second order elastic constants (SOEC) and Gruneisen parameters. These physical quantities have been calculated by making use of a phenomenological potential model. It has been found that the three-body interactions considered in the present potential model plays an important and significant role in explaining the characteristic behaviour of the crystals under study. Good agreement between the experimental and theoretical values has been obtained.