Heat Capacity ofβ-CuZn below 4.2°K

The specific heat of a series of high-purity $\beta$ brasses has been measured below 4.2°K. Because of the possibility of large contributions to the specific heat from small amounts of ferromagnetic impurities, each specimen was examined spectroscopically and was found to contain less than 1 part per million of Fe, Mn, and Co. The data were fitted by the method of least squares to a curve of the form $\frac{C}{T}=\gamma +\beta T^2+\delta T^4$, the $\delta T^4$ term being included to account for the apparently large phonon dispersion. All of the coefficients showed a marked decrease with increasing electron-atom ratio. The variation of electronic density of states as a function of electron-atom ratio is compared to the theoretical relation based on the nearly free electron approximation. For the specimen of approximately 50 at.% copper and zinc, $\gamma$ was found to be 0.699 mJ ${\mathrm{mole}}^{-1\mathrm{}}$ ${\mathrm{deg}}^{-2\mathrm{}}$ and the Debye temperature 291±2°K. This compares favorably with the value of 288±3°K, obtained from low-temperature elastic-constant measurements on an alloy of similar composition.