Heat Capacity of Pseudo-Copper below 4.2°K

Abstract

Heat-capacity measurements have been made on two face-centered-cubic alloys of the type ${\mathrm{Cu}}_{1-2x}{\mathrm{Zn}}_x{\mathrm{Ni}}_x$ at temperatures below 4.2°K for the values $x\approx 0.03$ and $x\approx 0.08$. The heat capacity has been found to obey a law of the type $C_v=\gamma T+\left(\frac{464.5}{{{\theta }_D}^3}\right)T^3$ cal/mole (°K). The Debye characteristic temperature ${\theta }_D$ is nearly the same as that for pure copper. For an alloy having $x\approx 0.03$, ${\theta }_D$ is approximately 1% higher than ${\theta }_D$ for pure copper. However, $\gamma$ increases rapidly with increasing $x$, and is approximately 20% higher than the $\gamma$ for pure copper when $x\approx 0.03$. The results are found to be incompatible with a rigid-band model approach to alloy theory.