We report $\beta$-detected nuclear magnetic resonance $\left(\beta \mathrm{NMR}\right)$ measurements of implanted ${}^8\mathrm{Li}^{+}$ in a synthetic single crystal of $\alpha \text{−}{\mathrm{SiO}}_2$ (quartz). At 6.55 Tesla, the spectrum is comprised of a large amplitude broad resonance and a quadrupolar multiplet that is only revealed by an rf comb excitation. The quadrupole splitting is surprisingly small, increases with temperature, and provides information on the implantation site. Supercell density functional theory calculations show the splitting is consistent with an in-channel interstitial site (Wyckoff $3a$). The spin-lattice relaxation is unexpectedly fast and strongly temperature dependent with a diffusive peak above 200 K and a second more prominent relaxation peak at lower temperature. Analysis of the diffusive relaxation yields an activation barrier 178(43) meV for the isolated ${\mathrm{Li}}^{+}$ in the range of other measurements and calculations. To account for many of the other features of the data, it is suggested that some of the implanted ions trap an electron forming the neutral ${\mathrm{Li}}^0$, which is stable over a narrow range of temperatures.

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• Defects
• Diffusion
• Ionic transport
• Lithium batteries
• Oxides
• Beta-detected nuclear magnetic resonance
• Nuclear magnetic resonance