Measurement of ∂P/∂T)v in solid hydrogen

Abstract

Abstract Measurements of ∂P/∂T)v in solid hydrogen below 4.2K are presented for orthohydrogen concentrations 0.55 ≥ X ≥ 0.20. The samples were measured in the temperature-concentration region associated with the formation of the quadrupolar glass. At slow cooling and warming rates no pressure anomaly or remanence was observed in the glass phase. Calculations made from extrapolations to T=0 indicate that the glass phase involves approximately 10% of the molecular rotational entropy.