Mössbauer study of sapphire irradiated with high energy heavy ions

Single crystals of Al2O3 samples were irradiated at GANIL with 4.32 MeV/amu 208Pb ions to fluences of 4 × 1011 and 8 × 1011 ions cm−2 and with 2.78 MeV/amu 238U ions to fluences of 1.2 × 1012 and 2.1 × 1012 ions cm−2 at a temperature of 77 K. Before irradiation the samples were implanted with 101657Fe ions cm−2 at 110 keV and annealed at 1673 K for 1 hour in order to introduce a local probe in very low concentration in the substitutional alumina sites. A conversion electron Mossbauer spectroscopy study (CEMS) was carried out so as to measure the effects of the high electronic energy losses. These results are discussed in comparison with those obtained by Rutherford backscattering spectrometry in channeling position. It should be pointed out that two specific iron sites appear after irradiation.