Local interactions of Fe-57 after electron capture of Co-57 implanted in alpha-Al2O3 and in alpha-Fe2O3

alpha-Al2O3 and alpha-Fe2O3 were implanted with Co-57 at room temperature, alpha-Al2O3 showed complex Mossbauer spectra indicating paramagnetic hyperf ine splitting for high-spin Fe3+ and electric quadrupole-split spectra for Fe2+ ions. In canted antiferromagnet alpha-Fe2O3, the implanted Co atoms we re 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+ star es after the electron capture of Co-57; no after-effects were observed. The results suggest that the phases are formed during fast cooling and crystal lization of the oxide from the high-temperature state of the thermal spike.