Journal of physics-condensed matter vol:12 issue:10 pages:2291-2296
alpha-Al2O3 and alpha-Fe2O3 were implanted with Co-57 at room temperature, alpha-Al2O3 showed complex Mossbauer spectra indicating paramagnetic hyperfine splitting for high-spin Fe3+ and electric quadrupole-split spectra for Fe2+ ions. In canted antiferromagnet alpha-Fe2O3, the implanted Co atoms were positioned substitutionally in Fe2O3 and at higher doses in Fe3O4 and in Fe1-xO. In the different phases, the ions were in Fe2+ and/or in Fe3+ stares after the electron capture of Co-57; no after-effects were observed. The results suggest that the phases are formed during fast cooling and crystallization of the oxide from the high-temperature state of the thermal spike.