Effect of impurity type on conduction electron scattering in lithium at 4.2°K
Abstract
The effect of eleven impurities (Cd, Al, Ag, Au, Mg, Zn, Hg, In, Tl, Ga, Pb) on the residual resistivity ρ0 of lithium has been studied. The alloys were prepared from commerical lithium of reduced residual resistivity δ0 = ρ0/ρ293 = (1 to 4)·10−3 with impurity concentrations 2·10−3 to 5 at.%. The solubility limits of In, Tl, Zn, Al, Ga, Pb, and Au impurities in solid lithium were determined for the first time. The measured values of Δρ0/c (the change in residual resistivity resulting from the solution of 1 at.% of an impurity) show a quadratic dependence on ΔZ, the difference between the valency of the V or VI period impurity and that of the host material. The Δρ/c values calculated by the phase shift method and pseudopotential theory (using the Appapillai form factors, derived from “first principles”, and the Ashcroft model potential) are in fair (the second calculation) and satisfactory (the first and third calculations) agreement with experiment. It is suggested that the sphericity of the Fermi surface is apparently a necessary though not the main condition for the applicability of all three calculations.