Electronic Specific Heat ofα-Phase Alloys Based on Copper and Silver

Electronic-specific-heat measurements have been made, in the liquid-helium temperature range, in the $\alpha$-phase fcc solid solutions of the following systems based on Cu or Ag: Cu-Ni, Cu-Zn, Cu-Ga, Cu-Ge, Ag-Ga, Ag-Ge, and Ag-In. An initial increase in the electronic-specific-heat coefficient $\gamma$ has been observed in all systems on alloying, and the initial electron-concentration derivatives of the density of states at the Fermi level, as indicated by the value of the coefficient ${\left[\frac{\partial \ln N{\mathrm{}\left(E\right)\mathrm{}}_F}{\partial \mathfrak{z}}\right]}_V$ are about 0.25 for all systems. The influence of atomic volume, as indicated by the coefficient ${\left[\frac{\partial \ln N\left(E_F\right)}{\partial \ln V}\right]}_{\mathfrak{z}}$, appears to be negligible. At higher solute concentrations, the trend of $\gamma$ and the limiting Debye temperature ${\Theta }_D$ do not superimpose when scaled to the same electron concentration. The above results are discussed in terms of the electronic band structure and the theories that take into account electron-impurity interactions, electron-phonon interactions, and volume effects.