Electronic properties and superconductivity of Zr-Pd glasses

Electrical-resistivity measurements between 1.4 and 300 K and room-temperature magnetic-susceptibility measurements were performed on the metallic glasses ${\mathrm{Zr}}_x{\mathrm{Pd}}_{1-x}$, for $x=0.59, 0.63, 0.67, \mathrm{and} 0.70$. The samples, prepared by a modified hammer-anvil technique, exhibit negative temperature coefficients of the resistivity at temperatures from about 10 to 300 K. These data can be understood in terms of the extended Ziman theory if it is assumed that Zr and Pd contribute about 2 and 1 conduction electrons, respectively. Assuming that the magnetic susceptibility is a qualitative measure of the electronic density of states at the Fermi level, $N\left(E_F\right)$, it is shown that $N\left(E_F\right)$ does not seem to decrease with composition as the eutectic composition is approached. Thus, for this system, there is no obvious correlation between the thermodynamic stability of the liquid phase and the electronic density of states. The superconducting transition temperature ($T_c$) scales linearly with $x$ and the valence-electron-per-atom ratio ($\mathfrak{z}$). However, as in the case for other intertransition-metal glasses composed of distant neighbors in the Periodic Table, $T_c\left(\mathfrak{z}\right)$ falls below the Collver-Hammond $T_c\left(\mathfrak{z}\right)$ curve for amorphous metals and alloys of neighboring metals of the $4d$ and $5d$ transition series.