Investigation of mean-square displacement and elastic moduli of solid argon up to 85 GPa

Abstract The pressure effects on lattice parameter, atomic mean-square displacement and elastic moduli (Young’s modulus, shear modulus and bulk modulus) of solid argon have been studied based on the so-called statistical moment method in statistical mechanics. The analytical expressions of these thermodynamic and elastic quantities have been derived. Numerical calculations up to pressure 85 GPa have been performed for argon by using the Buckingham potential to describe interaction between atoms. Present calculations reveal the strong pressure dependence of the atomic mean-square displacement and elastic moduli of argon crystal, especially at pressure below 10 GPa. However, elastic moduli are almost insensitive to temperature. Our theoretical model validity is demonstrated by the reasonable consistent with previous experimental measurements. This approach proposes an effective method for studying of mechanical and thermodynamic properties of materials at high pressure.