Lattice sites of ion-implanted Li in diamond

Radioactive Li ions were implanted into natural IIa diamonds at temperatures between 100 K and 900 K. Emission channelling patterns of $\alpha$-particles emitted in the nuclear decay of $^{8}$Li(t$_{1/2}$ = 838 ms) were measured and, from a comparison with calculated emission channelling and blocking effects from Monte Carlo simulations, the lattice sites taken up by the Li ions were quantitatively determined. A fraction of 40(5)% of the implanted Li ions were found to be located on tetrahedral interstitial lattice sites, and 17(5)% on substitutional sites. The fractions of implanted Li on the two lattice sites showed no change with temperature, indicating that Li diffusion does not take place within the time window of our measurements.