Muon spin relaxation measurements were performed in order to model the behaviour of H impurities. This oxide became a fast ion conductor at about 1000K, and the experiments also provided information on Li+ ion dynamics. Muon implantation at low temperatures (about 10K), created mainly neutral muonium (the analogue of the H atom) with a smaller fraction (some 20%) of positive muons at interstitial sites which were closely associated with O2- ions. At temperatures above 100K, the proportion of positive muons which formed increased, and there was an increased tendency to trapping at substitutional lattice sites. A sharp decrease in the relaxation rate was observed at temperatures above 250K. From this temperature dependence, it was deduced that Li+ ions were also mobile, and that the activation energy for motion relative to the Li+ ions was approximately 0.09eV.

Muon Sites and Diffusion in Lithium Oxide. J.S.Lord, S.P.Cottrell, W.G.Williams: Journal of Physics - Condensed Matter, 1998, 10[36], 7975-82