Organometallic Routes into the Nanorealms of Binary Fe-Si Phases

Abstract

The Fe-Si binary system provides several iron silicides that have varied and exceptional material properties with applications in the electronic industry. The well known Fe-Si binary silicides are Fe₃Si, Fe₅Si₃, FeSi, a-FeSi₂ and b-FeSi₂. While the iron-rich silicides Fe₃Si and Fe₅Si₃ are known to be room temperature ferromagnets, the stoichiometric FeSi is the only known transition metal Kondo insulator. Furthermore, Fe₅Si₃ has also been demonstrated to exhibit giant magnetoresistance (GMR). The silicon-rich b-FeSi₂ is a direct band gap material usable in light emitting diode (LED) applications. Typically, these silicides are synthesized by traditional solid-state reactions or by ion beam-induced mixing (IBM) of alternating metal and silicon layers. Alternatively, the utilization of organometallic compounds with reactive transition metal (Fe)-carbon bonds has opened various routes for the preparation of these silicides and the silicon-stabilized bcc- and fcc-Fe phases contained in the Fe-Si binary phase diagram. The unique interfacial interactions of carbon with the Fe and Si components have resulted in the preferential formation of nanoscale versions of these materials. This review will discuss such reactions.