Messung der spezifischen W�rme an Zr-Rh-Legierungen zwischen 0,9 und 12 �K

Abstract

The specific heats of Zr-Rh alloys have been measured between 0.9 and 12 °K, and at atomic percent Rh concentrations between 0 and 8. The transition temperatures (Tc), the electronic specific heats (γT), the electronic specific heats of superconducting state and the lattice specific heats [α(T/Θ)3] are calculated from the specific heat curves. The specimens with concentrations up to 3 At-% Rh are inhomogeneous. No sharp superconducting transitions are observed. The structure of the specimens between 3 and 7 At-% Rh is body centered cubic. In this phase Rh is dissolved nearly homogeneously. In this case the values ofTc,γ, andΘ are all rapidly varying and nearly linear functions of the atomic fractional Rh concentration. With the assumption that the measuredγ-values are connected with the density of electronic states according to the relation of the free electron gas one gets a surprising strong dependence of the interaction parameter responsible for superconductivity as a function of the Rh concentration. This change of the interaction parameter is essentially smaller, if additional terms of the specific heat linear inT do not allow to determine the density of electronic states directly fromγ. The superconducting state electronic specific heats obey the exponential law of the BCS theory.