New data on such relaxation in an amorphous La ternary alloy which contained a high concentration of interstitial H were presented. At the lowest measurement temperature, of about 10K, the relaxation profiles were consistent with fluctuating local fields with correlation times of a few s. The relaxation appeared to be characteristic of muon diffusion. At temperatures above 250K, where the diffusion hopping rate of the H atoms was 107 to 108/s (as measured by using nuclear relaxation methods), the correlation time varied rapidly with temperature. The change in relaxation of the muon spin at these temperatures was attributed mainly to the motion of the H atoms. In addition, measurements of muon spin relaxation in a sample of the same alloy, without absorbed H, were performed in the hope that these measurements would clarify the diffusion mechanism. However, comparison with the H-loaded samples was made difficult by the presence of marked temperature effects upon the local field distribution and correlation time.

X.Zhang, M.Kemali, R.L.Havill, J.M.Titman: Journal of Alloys and Compounds, 1995, 231, 262-6