Ion-beam mixing at the Fe/Al₂O₃ interface as revealed by conversion-electron Mossbauer spectroscopy

Abstract

The effects of ion-beam-induced atomic mixing and subsequent thermal treatments on the single-interface Fe/Al₂O₃ structure are investigated by use of the techniques of conversion-electron Mossbauer spectroscopy, small-angle x-ray diffraction, and resistivity measurements. On the basis of the average values of hyperfine-interaction parameters and also their distributions it is concluded that the as-mixed state of the interface consists of the FeAl₂O₄ phase along with nonstoichiometric FeO. Upon annealing at 600deC the mixed state leads to precipitation of α-Fe with a reduced contribution of FeAl₂O₄, via gradual transformations at lower annealing temperatures of 300deC and 450deC. These features are distinctly different as compared with the case of the thermally induced transformations in the as-deposited sandwich structure, which do not show formation of the FeAl₂O₄ phase. The dependence of the mixing reaction on the ion dose has also been investigated. Preliminary Mossbauer data on the influence of a pulsed ruby laser beam (694.3 nm) on the Fe/Al₂O₃ interface are also presented and compared with the data on ion-beam mixing.