Atom Movement inIn3LaStudied via Nuclear Quadrupole Relaxation

Abstract

Jump frequencies of Cd tracer atoms in In3La were measured via nuclear quadrupole relaxation caused by stochastic reorientation of the electric field gradient using the method of perturbed angular correlation of gamma rays. Activation enthalpies of 0.53(1) and 0.81(1) eV were found at the two phase boundaries, which differ in composition by only about 0.1 at. %. The jump frequency was found to be higher at the more In-rich phase boundary, ruling out a simple In-vacancy diffusion mechanism. Possible diffusion mechanisms and general applicability of the method are discussed.

Electric field gradients in the rare earth–aluminium compoundsRAl2andRAl3studied byForker1, Presa2 2007Phys. Rev. B

“…The jump frequencies in RIn 3 were found to depend sensitively on small deviations from the stoichiometric composition. [26][27][28] Slight composition differences are possibly responsible for the difference of the jump frequencies in RAl 3 , R = Tm, Lu and R = Yb.…”

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

“…2 shows that relaxation frequencies for the two samples are indistinguishable within the precision of measurement. This is a surprise since large differences have been observed for other "line compounds" such as for In 3 R phases having the L1 2 structure (R = rare earth) [4,5]. 3.…”

“…Both Ga 7 Pd 3 and Ga 7 Pt 3 phases appear as line compounds in binary phase diagrams. However, jump frequencies in other line compounds have been observed to differ appreciably for measurements made on samples prepared to have opposing boundary compositions [4]. Accordingly, measurements were made on samples having compositions of 27 and 31 at.% Pt, slightly greater and smaller than the stoichiometric composition.…”

“…Furthermore, when only the orientation of the EFG changes in a jump, as for Ga(3)-Ga(3) or for Ga(4)-Ga(4) jumps, the relaxation frequency λ is equal to the mean jump frequency, w (or inverse of the mean residence time). For a further description of relaxation due to diffusion of PAC probe atoms, see [4].…”

Simulation of PAC spectra for spin 5/2 probes diffusing via a simple vacancy mechanism in Cu 3 Au-structured intermetallic compounds

“…( * ) Diagonal elements are such that elements of columns sum to zero do not produce distinct signals disturb analysis of atomic jump rates. The present simulations of PAC perturbation functions were performed to address these issues for the special case of non-impurity PAC probes diffusing via a simple vacancy (SV) mechanism on the Cu-sublattice in Cu 3 Au-structured compounds, which is closely related to an earlier experimental study of Cd diffusion in In 3 La [1].…”