Longitudinal nuclear spin relaxation in liquid alloys of indium

Abstract

The longitudinal relaxation rate of the ¹¹⁵In nuclear spin in liquid In-Bi, Pb and Tl alloys is measured. The relaxation rate depends on both temperature and composition, and varies from 5200 s^-1 for pure liquid In to 6300 s^-1 for a 50 at% In-Bi alloy at 430K. The observations of Warren and Clark (1969) on In metal are used as a starting point from which deductions concerning the various contributions to the relaxation are made. It is found that the dependence on temperature may be accounted for by the presence of a contribution from the interaction of the nuclear quadrupole moments with the local electric field gradients which are themselves random functions of time due to the ionic motion. This contribution is found to be smaller than current theories predict, but the experimental observations are shown to support the proposal of the authors that there is a strong cancellation between the two and three atom contributions to the motion dependent quadrupolar relaxation rate in liquid metals.