Diffusion in binary and pseudo-binary L12 indides, stannides, gallides and aluminides of rare-earth elements as studied using perturbed angular correlation of 111In/Cd

TL;DR

This study uses perturbed angular correlation to measure atomic jump frequencies in ordered intermetallic compounds with L12 structure, revealing how composition and atomic substitution affect diffusion mechanisms in rare-earth indides, stannides, gallides, and aluminides.

Contribution

It provides new experimental data on atomic jump frequencies in pseudo-binary L12 compounds and analyzes how substitution influences diffusion behavior in these ordered intermetallics.

Findings

Jump frequencies scale with composition in rare-earth systems.

Sn substitution significantly decreases jump frequency in In3La.

Diffusion mechanisms depend on atomic disorder and valence differences.

Abstract

Diffusional jumps can produce fluctuating electric field gradients at nuclei of jumping atoms. Using perturbed angular correlation of gamma rays (PAC), jumps of probe atoms cause nuclear quadrupole relaxation that can be fitted to obtain the mean jump frequency. An overview is given of the application of this approach to highly ordered intermetallic compounds having the L12 (Cu3Au) crystal structure. New results are then presented for jump frequencies of 111In/Cd probe atoms in pseudo-binary L12 compounds of the forms In3(La1-xPrx) and (In1-xSnx)3La. For the mixed rare-earth system, jump frequencies are found to scale with composition between jump frequencies of the end-member phases In3La and In3Pr. However, for the mixed sp-element system, a large decrease in jump frequency is observed as Sn atoms substitute for In-atoms. This difference in behavior appears to depend on whether atomic disorder is on the diffusion sublattice (In-Sn substitution), as opposed to a neighboring sublattice (La-Pr substitution), whether or not there is a difference in diffusion mechanism between end-member phases, and/or whether or not there is a valence difference between the mixing atoms. All three conditions apply for only (In1-xSnx)3La.