Formation and low-temperature electronic properties of liquid-quenched Ag-Cu-X (X=Mg, Si, Sn and Sb) metallic glasses

Abstract

The glass-forming region in liquid-quenched Ag-Cu-X (X=Mg, Al, In, Si, Sn and Sb) alloy systems was investigated by utilising the melt-spinning technique. The electrical resistivities were measured in the range 2-700K and the low-temperature specific heats in the range 1.5-6K for these Hume-Rothery-type simple metallic glasses. A distinct difference is found to exist in the low-temperature electronic properties between the low-resistivity Ag-Cu-Mg and Ag-Cu-Sn alloys and high-resistivity Ag-Cu-metalloid alloys. The temperature dependence of the electrical resistivity can be discussed within the framework of the extended Ziman theory. The sign of the TCR can be well correlated with Ziman's parameter 2kF/Kp only for the low-resistivity alloys. The saturation effect develops in the high-resistivity alloys. This can be easily identified from the unique temperature dependence of the resistivity at low temperatures below about 100K. The electronic specific heat coefficient data for the low-resistivity Ag-Cu-Mg alloys can be well understood in terms of the free-electron model. Furthermore, it turns out that the 2kF=Kp condition does not noticeably affect the density of states at the Fermi level. However, some depression of the density of states at the Fermi level is apparently present in the case of Ag-Cu-metalloid metallic glasses.