Direct measurements of the constant-volume heat capacity of solid parahydrogen from 22.79 to 16.19/mole and the resulting equation of state
- 15 March 1980
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review B
- Vol. 21 (6), 2533-2548
- https://doi.org/10.1103/physrevb.21.2533
Abstract
The constant-volume heat capacity of solid parahydrogen () has been measured directly from below 4 K to the melting line for six molar volumes (22.787 to 16.19 /mole). These data have been analyzed using the Mie-Grüneisen equation of state (EOS) to give the volume and temperature dependence of the Grüneisen parameter and the EOS for , as well as the volume dependence of the quadrupole-quadrupole interaction parameter for orthohydrogen impurities. Good agreement is found with earlier 4-K high-pressure compression data, and reasonable agreement with direct strain-gauge measurements of . The thermodynamic properties for solid at are obtained by extrapolation to larger molar volumes, with the , equilibrium volume given as 23.234 (±0.05) /mole and the triple-point volume of the solid as 23.48 (±0.05) /mole. The rather large temperature dependence of the Grüneisen parameter which results from a comparison with high-pressure melting-line data is discussed in terms of an explicit temperature dependence of the lattice vibration spectrum. No indications were found for phase transitions in solid , nor for premelting anomalies.
Keywords
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