Ion irradiation damage in ilmenite under cryogenic conditions

摘要

A natural single crystal of ilmenite was irradiated at 100 K with 200 keV Ar(sup 2+). Rutherford backscattering spectroscopy and ion channeling with 2 MeV He(sup +) ions were used to monitor damage accumulation in the surface region of the implanted crystal. At an irradiation fluence of 1 (times) 10(sup 15) Ar(sup 2+) cm(sup (minus)2), considerable near-surface He(sup +) ion dechanneling was observed, to the extent that ion yield from a portion of the aligned crystal spectrum reached the yield level of a random spectrum. This observation suggests that the near-surface region of the crystal was amorphized by the implantation. Cross-sectional transmission electron microscopy and electron diffraction on this sample confirmed the presence of a 150 mm thick amorphous layer. These results are compared to similar investigations on geikielite (MgTiO(sub 3)) and spinel (MgAl(sub 2)O(sub 4)) to explore factors that may influence radiation damage response in oxides.