Knight shifts in binary liquid alloys of equi-valent metals

Abstract

The N.M.R. Knight shift depends upon the conduction electron density at the nucleus under observation. An interpretation of its absolute magnitude in liquid metals cannot be undertaken in terms of a pseudopotential formulation, but relative changes of shift with some parameter such as temperature, volume or alloy composition can be investigated. Knight shift changes with concentration have been measured for a series of binary liquid alloys. Since application of a pseudopotential treatment is simplest when the two constituents have the same valency, the alloys chosen have mostly been of this type, e.g. In-Ga, In-Tl, Sn-Pb, Sb-Bi. Although theory predicts the correct qualitative behaviour of the shift changes, the precise theoretical predictions are very sensitive to details of both the pseudopotentials and the liquid structure factor. In the case of In-Sn and In-Pb, where the shifts of both constituents decrease with increasing indium content for In-Sn, but increase for In-Pb, the difference between the pseudopotentials of tin and lead does not appear to be sufficient to explain the observed differences in changes of shift.