Using perturbed angular correlation spectroscopy (PAC), jump frequencies of Cd tracer atoms were measured for 12 indides In₃B (B= rare earth) in paired samples having compositions at each of the opposing phase boundaries.   Jump frequencies in heavy lanthanide indides were observed to be smaller for In-richer compositions than for In-poorer compositions, but greater in the light lanthanide indides.  These findings signal an unmistakable change in diffusion mechanism from the simple In-sublattice vacancy mechanism for heavy lanthanides to a B-vacancy mechanism for light lanthanides.

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.

Jump frequencies of tracer atoms in the intermetallic compound Ga₇Pd₃ were determined through observation of fluctuating nuclear quadrupole interactions caused by the jumps.  Measurements were made for 111Cd tracer atoms following decay of 111In using the method of perturbed angular correlation of gamma rays (PAC).  Tracers were found to occupy two inequivalent Ga-sublattices, with distinct quadrupole perturbation functions.  The two sublattices interpenetrate and long-range three-dimensional diffusion is possible on either sublattice via near-neighbor jumps.  Measurements at elevated temperature exhibited damping of static quadrupole perturbation functions G_2static (t) that was fitted for each signal using the approximation G₂ (t)= exp(-wt) G_2static (t), in which w is the jump frequency of the tracer.  Arrhenius plots of w for the two sites exhibited thermal activation with activation enthalpies of 0.49(2) and 0.44(4) eV and jump frequency prefactors close to 2 × 10¹¹ Hz.  Possible scenarios to interpret the results in terms of underlying inter- and intra-sublattice jumps are discussed.