Studies of small Fe-Sn clusters in an argon matrix

The Mössbauer effect in ${}_{}{}^{119}{}_{}{}^{}\mathrm{Sn}$ and ${}_{}{}^{57}{}_{}{}^{}\mathrm{Fe}$ was employed to study and characterize small clusters of ${\mathrm{Fe}}_x{\mathrm{Sn}}_y$ formed and stabilized in a solid argon matrix. Various low concentrations of Fe and Sn atoms in Ar were used (0.1-0.5 at.%), resulting in formation of dimers and trimers. The constituents and geometrical structures were confirmed by self-consistent assignment of the ${}_{}{}^{57}{}_{}{}^{}\mathrm{Fe}$ isomer shift, quadrupole splitting, linewidth, and relative intensities of the ${}_{}{}^{57}{}_{}{}^{}\mathrm{Fe}$ and ${}_{}{}^{119}{}_{}{}^{}\mathrm{Sn}$ lines. Apart from the monomers and dimers of Fe and Sn, the following species were characterized: FeSn, ${\mathrm{Fe}}_2$Sn, Fe${\mathrm{Sn}}_2$, SnFeSn, and ${\mathrm{Fe}}_3$. Conclusions were drawn regarding the reactivity of Fe and Sn atoms and dimers in the matrix preceding solidification of argon. The nature of the Fe—Sn bond is discussed in terms of the ${}_{}{}^{57}{}_{}{}^{}\mathrm{Fe}$ hyperfine constants.