銅合金液体のホール係数について

Abstract

Hall coefficients of liquid copper alloys Cu-Bi, Cu-Sb, Cu-Sn and Cu-In were measured by means of the two-alternating current method in a wide temperature range from 500 to 950°C.No temperature dependence of the Hall coefficient was observed in the liquid state of these alloys. The observed composition dependence of the Hall coefficient for the liquid Cu-Bi alloy was in good agreement with that calculated under the assumption of random mixing of Cu+1 and Bi+5 ions and of free electron approximation. In the other copper alloys, however, deviations from the free electron values R0 calculated under the above simple situation were observed. It is considered that some of the constituent atoms are randomly distributed and others are associated into clusters consisting of several atoms in the liquid states of Cu-In, Cu-Sn and Cu-Sb alloys. Such a cluster is referred to as a pseudo-molecule. A theoretical formula for the Hall coefficients of these liquid alloys was derived as a function of concentration of the pseudo-molecules nR⁄N, the number of localized electrons contributing to the bonding of the pseudo-molecule 2p and an effective volume of pseudo-molecule seen by conduction electrons αΩ0. Using the values of nR⁄N, 2p and αΩ0 obtained from the observations of other physical properties such as heat of mixing, magnetic susceptibility and electric resistivity, the calculated composition dependences of the Hall coefficients of the liquid Cu-In and Cu-Sn alloys were in good agreement with the observed ones. It was shown experimentally that the temperature dependence of the Hall coefficients estimated from the above formula was negligibly small.