(583g) Phase Transformation As a Strategy for the Synthesis and Assembly Via Welding of Single-Crystalline Metal Silicide Nanowires

A simple and versatile strategy for not only the synthesis, but also the large-scale assembly via welding of single-crystalline metal silicide nanowires was developed. The strategy relies on the solid-state phase transformation of pre-synthesized silicon nanowires that have sharp tips. Experiments performed using Mg₂Si materials system as an illustrative example indicated that both the formation and welding of Mg₂Si nanowires is possible using solid-state phase transformation. The use of sharp tipped nanowires, in conjunction with solid-sate phase transformation, circumvented the formation of multiple Mg₂Si nuclei within the nanowire during phase transformation, and hence the formation of polycrystalline Mg₂Si nanowires. Furthermore, simultaneous synthesis and the large-scale assembly of the nanowires via welding were accomplished by the phase transformation of silica nanoparticle decorated silicon nanowires. Phase transformation of silica nanoparticle decorated silicon nanowires with magnesium foils results in the formation of single-crystalline Mg₂Si nanowires that are bridged together via Mg₂Si bridges. This strategy allows for the large-scale assembly of nanowires in an interface-engineered manner, unlike traditional nanowire assembly strategies that result in the formation of oxides hat have electrically-insulating MgO at the interfaces. Such welding of nanowires is expected to offer the ability to independently tune thermal and electrical transport, and the fabrication of highly efficient thermoelectrics.