After the discovery of carbon nanotubes, one-dimensional nanostructure materials have been attracting increased because of their unique chemical and physical properties and potential application in areas such as electronic and optical devices. Among many one-dimensional nanostructure materials, boron nanowires arouse great interest from both scientific and technological areas of research. Boron has a high melting point over 2300°C, low density, moderate oxidation resistance, hardness that is similar to that of the diamond. The theoretical calculation shows that the boron nanotubes have higher electrical conductivity than carbon nanotubes. The experiment proved that single crystalline boron nanowires are semi-conducting and exhibit electrical properties consistent with those of elemental boron. The application of boron includes high temperature devices, nuclear engineering, high-engineering fuel, and light-weight protective.
Here, we report that large scale single-crystal boron nanowires grown on silicon substrates were successfully synthesized by thermal carbon reduction of B2O3 powders. The morphology, structure and the composition of the crystalline boron nanowires were investigate in detail by means of scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) and electron energy loss spectroscopy (EELS). The boron nanowires are single crystals with tetragonal structure, and they have uniform lengths of several micrometers and diameters of 10~50 nm. The possible growth mechanism of the crystalline boron nanowires is discussed.
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