Defects induced melting in alkali halides

► We have studied the pressure dependence of melting in alkali halides on the basis of the vacancy model. ► We have taken into account the pressure dependence of volume of Schottky defects. ► The pressure derivatives of melting temperature are calculated for the alkali halide solids. ► The results have been found to compare well with the corresponding experimental data. ► This work will be useful in the analysis of thermal equation of state for solids.