Processing and characterization of single-crystalline ultrafine bismuth nanowires

By pressure injecting Bi liquid melt into the nanochannels of an anodic alumina template, we have successfully fabricated Bi nanowire arrays with ultrafine wire diameters and extremely high wire packing densities. Free-standing Bi nanowires with controlled wire diameters and large aspect ratios (length/diameter) were also obtained by subsequent etching of the alumina template. Various techniques such as SEM, TEM, AFM, EFM, HREM, and XRD have been used to investigate the physical characteristics of these nanowires. The Bi nanowires were found to be dense and continuous and had a uniform diameter throughout the length of the wires. Individual Bi nanowires were shown to be single crystals, and all the wires in an array were highly oriented. An interesting metastable phase of Bi was also observed, which can be attributed to a lattice stress-induced high-pressure phase of Bi formed inside the porous anodic alumina template.