Lattice locations and properties of Fe in Co/Fe co-implanted ZnO

The lattice locations and electronic configurations of Fe in 57Co/57Fe implantedZnO (to (5-6) × 1014 Fe/cm-2) have been studied by 57Fe Mössbauer emission spectroscopy. The spectra acquired upon room temperatureimplantation show ~20% of the probe atoms as Fe2+ on perturbed Zn sites and the remaining fraction as Fe2+ in damage sites of interstitial character. After annealing at 773 K, ~20% remain on crystalline sites, while the damage fraction has partly disappeared and instead a ~30% fraction occurs as high-spin Fe3+, presumably in precipitates. This suggests that precipitation of Co/Fe in ZnO likely takes place at relatively low temperatures, thus explaining some of the discrepancies in the literature regarding magnetic properties of 3d metal-doped ZnO.