A New Approach to Estimate the Melting Temperature Variation with Pressure in Alkali Halides

Abstract

In the present study, the variation in melting temperature of alkali halides is studied with repect to pressure using the Lindemann –Gilvarry law for melting. The model requires the value of Grüneisen parameter along with volume compression. The Equation of state used to estimate the variation of volume with isothermal pressure is Goyal and Gupta EoS. The EoS satisfies Stacey’s criteria which confirm the validity of Goyal and Gupta EoS at high pressure values. It is found from model calculations that Grüneisen parameter decreases with increase in pressure, however, melting temperature increases with pressure non-linearly as the slope of melting curve is found to decrease continuously as pressure increases. The variation of Grüneisen parameter with pressure matches with the general trend of variation as depicted in previous studies. The present computed results for pressure dependent melting temperature are compared with the available experimental results which present a good consistency between the compared results. The approach formulated can be used to estimate the melting temperature of solids at high pressure values and is simpler than DFT computations.