Diffusion of 111Cd probes in Ga7Pt3 studied via nuclear quadrupole relaxation

Diffusion of 111In/Cd impurity atoms was studied in Ga7Pt3 at the atomic level using the method of perturbed angular correlation of gamma rays (PAC). As in previous measurements on Ga7Pd3, probes were observed to occupy two inequivalent Ga-sublattices. Quadrupole interaction perturbation functions for each site exhibited damping at elevated temperatures that is attributed to nuclear relaxation caused by stochastic jumps of the probe atoms accompanied by reorientation of axes of the electric field gradient tensor. Fitted relaxation frequencies, proportional to mean jump frequencies of the probe, were thermally activated. Arrhenius plots revealed jump-frequency activation enthalpies of 0.94 (8) and 0.67 (4) eV for the two sites and frequency prefactors close to 1 THz. Results were similar to those found previously for Ga7Pd3, although jump frequencies are about 100 times lower in Ga7Pt3.