Mössbauer-effect study of ferromagneticDO3-structured iron-aluminum-silicon alloys

Mössbauer-effect spectroscopy has been used to measure the temperature dependence of the ${}_{}{}^{57}{}_{}{}^{}\mathrm{Fe}$ effective magnetic hyperfine field $H_{\mathrm{eff}}$ and isomer shift $\delta$ across the entire ${\mathrm{Fe}}_3{\mathrm{Al}}_x{\mathrm{Si}}_{1-x}$ system ($0<~x<~1$) from 77 K to the Curie temperature, the latter also being determined from these measurements. The observed dependence of $H_{\mathrm{eff}}$ and $\delta$ on Al concentration can be qualitatively understood in terms of the calculated band structure of ${\mathrm{Fe}}_3$Si. The changes in $H_{\mathrm{eff}}$ and $\delta$ at the $B$ sites with increasing Al concentration are due primarily to a decrease in the number of spin-up electrons at these sites, whereas the changes in $H_{\mathrm{eff}}$ and $\delta$ at the $A$,$C$ sites result primarily from a decrease in the number of spin-down electrons at these sites.