Temperature and diffusion effects in preferential sputtering of CrSi2

We found a marked variation with temperature of the composition of CrSi2 under irradiation with 100 keV Xe+ ions. At the same time the composition of material sputtered did not change significantly with temperature. Sputtered material was collected from some of the samples on carbon sheets. Both, carbon collectors and irradiated samples, were analyzed by backscattering spectrometry. Samples irradiated at room temperature and 1000C showed an enrichment of Cr through the implanted region, while samples irradiated at 2800C had a composition near that of unirradiated samples. The Si to Cr ratio in the sputtered material was slightly above that of the bulk composition at all temperatures measured. The results at lower temperatures can be explained by preferential sputtering of Si and enhanced diffusion in the irradiated region. To explain high temperature results, we assume that some process at the surface, probably formation of an equilibrium phase, limits atomic transport. (orig.)