Low temperature specific heats in dilute Pd-H alloys

Abstract

Low temperature specific heats have been measured between 1.5 and 4.2K, in pure Pd and two Pd-H alpha phase alloys of H/Pd ratio 0.0051 and 0.0075, respectively. Very little change was observed on alloying in the lattice specific heat coefficient (Debye coefficient), but a measurable decrease was observed in the electronic specific heat coefficient. The decrease of the latter is similar to that indicated by the recent band calculations, with the assumption that enhancements due to electron-phonon interactions and other effects are the same as those in pure Pd. It is concluded that the hydrogen atoms contribute their electrons to the host metal conduction band and that the changes near the Fermi level in the very dilute alpha phase alloys can be described adequately by the band structure of pure Pd.