Anomalous electrical conductivity in rapidly crystallized Cu${}_{50-x}$Zr${}_{x}$ (x = 50 - 66.6) alloys

TL;DR

This study investigates the anomalous electrical conductivity in rapidly crystallized Cu-Zr alloys, revealing non-standard resistivity behavior at low and high temperatures, and proposing a generalized model to explain these phenomena.

Contribution

The paper introduces a generalized Bloch–Grüneisen model with variable Debye temperature to accurately describe the resistivity of Cu-Zr alloys exhibiting anomalous behavior.

Findings

Electrical resistivity shows non-monotonous temperature dependence below 20 K.

Resistivity at high temperatures cannot be explained by the standard Bloch–Grüneisen model.

Both resistivity and Hall coefficients indicate metallic conductivity with significant lattice defects.

Abstract

Cu${}_{50-x}$Zr${}_{x}$ (x = 50, 54, 60 and 66.6) polycrystalline alloys were prepared by arc-melting. The crystal structure of the ingots has been examined by X-ray diffraction. Non-equilibrium martensitic phases with monoclinic structure were detected in all the alloys except Cu${}_{33.4}$Zr${}_{66.6}$. Temperature dependencies of electrical resistivity in the temperature range of T = 4 - 300 K have been measured as well as room temperature values of Hall coefficients and thermal conductivity. Electrical resistivity demonstrates anomalous behavior. At the temperatures lower than 20 K, their temperature dependencies are non-monotonous with pronounced minima. At elevated temperatures they have sufficiently non-linear character which cannot be described within framework of the standard Bloch--Gr\"{u}neisen model. We propose generalized Bloch--Gr\"{u}neisen model with variable Debye temperature which describes experimental resistivity dependencies with high accuracy. We found that both the electrical resistivity and the Hall coefficients reveal metallic-type conductivity in the Cu-Zr alloys. The estimated values of both the charge carrier mobility and the phonon contribution to thermal and electric conductivity indicate the strong lattice defects and structure disorder.