8Li in GaAs studied with β-NMR

β-NMR has been used to study isolated spin polarized Li+8 in bulk crystalline GaAs. At low temperatures a large fraction (at least 70%) of the Li end up in locations with cubic symmetry (e.g. a tetrahedral interstitial site). The linewidth of the β-NMR Li+8 resonance increases dramatically above 150 K, and reaches a maximum at about 290 K. These results are consistent with a site change from an interstitial to a substitutional beginning at ≈150K. The field dependence of the linewidth at 100 K is also discussed.