Early 8 Li + β NMR investigations in GaAs and Ge
ABSTRACT 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 ≈3T 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 β-NMR Li+8 resonance increases dramatically above 150K, reaches a maximum at about 290K, and decreases again. This suggests that the Li starts to change its location, probably from an interstitial to a substitutional site, at ≈150K. 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.