Direct synthesis of silicon nanowires, silica nanospheres, and wire-like nanosphere agglomerates

Elevated temperature synthesis has been used to generate virtually defect free SiO2 sheathed crystalline silicon nanowires and silica (SiO2) nanospheres which can be agglomerated to wire-like configurations impregnated with crystalline silicon. The SiO2 passivated (sheathed) crystalline silicon nanowires, generated with a modified approach using a heated Si-SiO2 mix, with their axes parallel to [111] are found to be virtually defect free. Modifications to the system allow the simultaneous formation of SiO2 nanospheres (d similar to 10-30 nm) as virtually monodisperse gram quantity powders which form large surface area catalysts for the selective conversion of ethanol to acetaldehyde. (C) 2000 American Institute of Physics. [S0003-6951(00)00717-8].