Specific heats of solid natural neon at five molar volumes and of the separated neon isotopes atP=0

Abstract

Direct measurements of the constant volume specific heatC v are reported for solid natural neon at several molar volumes (13.39–12.39 cm3/mole) at temperatures from 1 K to the melting line. All samples were solidified in a high-pressure bomb at the melting line (maximum conditions of 53 K and 2.5 kbar) and molar volumes for the melting line are given. The extrapolations of these data to 0 K result in a↺ 0(V) relation for which↺ 0(P=0,T=0)=75.1±0.1 K and an average Gruneisen parameter γ0=2.51±0.03. These data can be represented at all temperatures and for all volumes by a single reduced curve asC V [T/↺ 0(V)], with a maximum deviation of ±0.8% nearT/↺ 0=0.12. The deviations are systematic with volume and consistent with a temperature-dependent contribution to the Gruneisen parameter of 1±1%. The melting line parameters are used to test the Lindeman melting relation, and systematic deviations are found. Much less complete measurements ofC V for the separated neon isotopes20Ne and22Ne are consistent with the reduced curve for natural neon, and with anM −0.5dependence for↺ 0, where M is the isotopic mass.