Fe-57 Emission Mossbauer Study on Gd3Ga5O12 implanted with dilute Mn-57

Fe-57 emission Mossbauer 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 of Mn-57 (T-1/2 = 1.5 min.) at ISOLDE/CERN. These results are compared with earlier Mossbauer spectroscopy study of Fe-doped gadolinium garnet Gd3Ga5O12(GGG), with implantation fluences between 8x10(15) and 6x10(16) atoms cm(-2). Three Fe components are observed in the emission M " ossbauer 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 daughter (57)*Fe nucleus in the beta(-) decay of Mn-57. In contrast to high fluence Fe-57 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.