In this paper, we describe initial studies of the structure and dynamics associated with Li-8(+) in bulk crystalline GaAs and Ge. At low temperatures in GaAs, the amplitude of the Li-8(+) resonance signal at approximate to 3 T indicates that a large fraction (at least 70%) of the Li end up in locations with cubic symmetry (i.e. the tetrahedral interstitial and substitutional sites). The linewidth of the beta-NMR Li-8(+) resonance increases dramatically above 150 K, reaches a maximum at about 290 K, and decreases again. This suggests that the Li starts to change its location, probably from an interstitial to a substitutional site, at approximate to 150 K. Experiments in Ge are also described. In this sample, a narrow resonance is seen at low temperatures that is likely due to Li located at an interstitial site. Near room temperature, it appears that Li is converting to another site. (c) 2005 Elsevier B.V. All rights reserved.
