EXPERIMENTAL-DETERMINATION OF THE EQUATION OF STATE OF SOLID HYDROGEN AND DEUTERIUM AT HIGH-PRESSURES

Isochores of solid hydrogen and deuterium have been measured for melting line pressures up to 2000 bar. These are corrected to correspond to para-H2 and ortho-D2. The 4.2 K isotherm of H2 has been determined and compared to the extrapolated low-pressure isochore of Anderson and Swenson (AS). Deviations have led us to reanalyze the AS data. The 4.2 K isotherm and the isochores are used, with the aid of a Mie-Grüneisen analysis, to determine P-V-T data for these solids up to 25 kbar. An analysis is presented which enables a determination of P-V-T-C1 for all values of C1, the ortho-para concentration. Results, including the Debye temperature, Grüneisen constant, and bulk modulus, are presented both in tabulated and graphical form. We also present what we feel to be the best of the 4.2 K, zero-pressure molar volumes of disordered H2 and D2 as a function of C1. Our measurements show no indication of the premelting phase transition reported in recent Russian literature and a possible explanation is presented. © 1979 Plenum Publishing Corporation.