ELECTRONIC SPECIFIC-HEATS IN METAL-HYDROGEN SYSTEMS

The electronic specific heats of metals and metal–hydrogen systems can in many cases be evaluated from the measured specific heats at constant pressure, Cp, in the temperature range 1 to 10 K. For the simplest case, Cp = γT+βT3, where γT represents the specific heat contribution associated with the conduction electrons, and βT3, represents lattice specific heat contribution. The electronic specific heat coefficient, γ, is important because it is proportional to electron density of states at the Fermi surface. A short description of a low temperature calorimetrie cryostat employing a 3He/4He dilution refrigeration is given. Various considerations and complications encountered in the evaluation of γ from specific heat data are discussed.Finally, the experimental values of γ for the V – Cr – H system and for the Lu – H system are summarized and the variations of γ as function of alloy composition are discussed. © by Akademische Verlagsgesellschaft