Equation-of-state and melting curve of solid neon and argon up to 100 GPa

Abstract

Equation-of-state and melting curve of neon and argon solids at high pressure are investigated based on the statistical moment method taking into account the anharmonicity contributions of thermal lattice vibrations. We have derived the analytical expression of equation-of-state and proposed a procedure to calculate melting temperature of materials at high pressure. We perform numerical calculations for neon and argon solids up to 100 GPa by using the Buckingham function (exp-6) to model the interaction between atoms. Our theoretical calculations reveal the strong dependence of the lattice constant and melting temperature on pressure of rare-gas solids, in particular at below 10 GPa. The derived equation-of-states of neon and argon go along with earlier experiments up to pressure 100 GPa. The present argon melting curve is in good agreement with previous measurements up to pressure 80 GPa. Our melting line of neon can reproduce well melting data points using W absorbers with thickness 8 μm and 6–8 μm up to pressure nearly 80 GPa, and differs from the measurements using W absorbers with thickness 4–6 μm.