Indexed on: 22 Feb '16Published on: 22 Feb '16Published in: Hyperfine Interactions
57Fe emission Mössbauer spectroscopy has been applied to study the lattice location and properties of Fe in gadolinium gallium garnet Gd3Ga5O12 (GGG) single crystals in the temperature interval 300 – 563 K within the extremely dilute (<10−4 at.%) regime following the implantation of57Mn (T1/2= 1.5 min.) at ISOLDE/CERN. These results are compared with earlier Mössbauer spectroscopy study of Fe-doped gadolinium gallium garnet Gd3Ga5O12(GGG), with implantation fluences between 8×1015 and 6×1016 atoms cm−2. Three Fe components are observed in the emission Mössbauer spectra: (i) high spin Fe2+ located at damage sites due to the implantation process, (ii) high spin Fe3+ at substitutional tetrahedral Ga sites, and (iii) interstitial Fe, probably due to the recoil imparted on the daughter57∗Fe nucleus in the β− decay of57Mn. In contrast to high fluence57Fe implantation studies the Fe3+ ions are found to prefer the tetrahedral Ga site over the octahedral Ga site. No annealing stages are evident in the temperature range investigated. Despite the very low concentration, high-spin Fe3+ shows fast spin relaxation, presumably due to an indirect interaction between nearby gadolinium atoms.