Anharmonic elastic behaviour and Gruneisen parameters of hexahalometallate crystals

The third-order elastic constants (TOEC), pressure derivatives of second-order elastic constants (SOEC) and Griineisen parameters of A,BX,-type single crystals such as K,SnCI,, K,ReCI,, (NH,),SnCI, and (NH,),SnBr, have been calculated on a microscopic scale, in order to analyse the anharmonicity in these hexahalometallate crystals. The input data used for determining the model parameters are considered at room temperature. The calculated values of TOEC combinations are found to be negative while positive values are found for pressure derivatives Of SOEC in all the four crystals under study. The experimental values of these properties have also been shown for the sake of comparison. A fairly good agreement between theoretical and experimental results is obtained.