RESISTIVITY AND KNIGHT-SHIFT OF LIQUID LI-GA ALLOYS

Abstract

The electrical resistivity rho and the 7Li and 71Ga Knight shifts of liquid Li-Ga alloys were measured. The maximum value of rho on the isotherm at 775 K is 161.1 mu Omega cm at 32.6 at.% Ga. The temperature coefficient delta rho / delta T exhibits a negative minimum at this concentration. This value of rho for liquid Li-Ga alloys does not exceed values appropriate to the nearly free electron (NFE) model; resistivity values calculated by the Faber-Ziman formula are in fair agreement with experiment, though the peak position of the calculated isotherm of rho is shifted slightly to the Li-rich side. However, the experimental Knight shifts provide clear evidence of charge transfer from Li to Ga. The Knight shift KLi of 7Li decreases rapidly with the addition of Ga up to 30 at.% Ga where rho is maximum. Beyond this Ga concentration KLi becomes constant. On the other hand, the Knight shift of 71Ga, KGa, decreases almost linearly with the addition of Li up to 53 at.% Ga. This is attributed to increasing p character of the Ga conduction electrons if 7Li is added. For a more quantitative interpretation it will be necessary to incorporate charge transfer in the NFE model.