Specific Heat and Residual Resistivity of Binary and Ternary Noble-Metal Alloys

Electronic specific-heat and residual-resistivity measurements have been made on the Ag_αAu_1-α binary and the Ag_α(60 at.% Au-40 at.% Cu)_1-α ternary disordered alloy systems as well as the two individual samples of Ag0.5{(72{{0ex}{0ex}}at.%{{0ex}{0ex}}Au{-}28{{0ex}{0ex}}at.%{{0ex}{0ex}}Cu)}0.5$ and ${Ag}0.5$${(84{{0ex}{0ex}}at.%{{0ex}{0ex}}Au{-}16{{0ex}{0ex}}at.%{{0ex}{0ex}}Cu)}0.5$. The residual resistances of the binary and ternary systems are found to obey Nordheim's rule only as a first approximation. Specific-heat measurements on the binary system confirm previously published results. Two theories explain the latter either in terms of electron-phonon interactions or electron-impurity interactions. These theories have been extended to a ternary mixture of noble metals, where each predicts a different concentration dependence for the electronic specific heat. The measured results on the ternary alloys are compared with the analytical predictions to distinguish between the two processes involved.