Samples of sapphire were implanted with Hf, at room temperature, to a dose of 5 x 1014/cm2. The lattice location of the Hf was studied by means of Rutherford back-scattering spectrometry and channelling, and the recovery of isolated point defects was studied by monitoring hyperfine interactions. It was shown that, after implantation, Hf substituted for Al. Lattice recovery of the point defects which were created by implantation was achieved by furnace annealing at 350 to 550C.

J.G.Marques, A.A.Melo, J.C.Soares, E.Alves, M.F.Da Silva, K.Freitag: Nuclear Instruments and Methods in Physics Research B, 1995, 106[1-4], 602-5