Microstructural differences between sendust(FeSiAl) films sputtered in pure Ar atmosphere and FeSiA1N films sputtered in Ar+4%N2 mixture atmosphere were measured using Mössbauer effect. These films were prepared by a conventional RF sputtering method. As a source for the Mössbauer measurement, 57Co was used.
Before annealing, there are no differences between both films in Mössbauer spectra. The both patterns are observed as simple six-line spectra from Fe atoms in a disordered structure. After annealing, both patterns are not simple six-line spectra, which indicate there are more than two types Fe site in the crystal. A tremendous difference between both films appears in the spectra. 95% Fe atoms of FeSiAl film are at the two different sites of D03 structure. However, in FeSiAlN film, only 54& Fe atoms are at the D03 sites and about 30% Fe atoms are at different sites whose hyperfine field is about-250kOe. This value of hyperfine field is expected at a D03-like site with 5 Fe nearest neighbors. This D03-like site is explained as a site that one Fe atom is substituted for one D-site Si or Al atom in a D03 unit cell.
No Fe-nitrides were observed in FeSiAlN films.