Morphology-tuned synthesis of single-crystalline V₅Si ₃ nanotubes and nanowires

We report the morphology-tuned synthesis of single-crystalline V ₅Si₃ nanotubes and nanowires. Free-standing hexagonal V₅Si₃ nanostructures are grown on a vanadium foil substrate placed on Si powder by a chemical vapor deposition method. By controlling the reaction time and substrate temperature, we have succeeded in morphology tuning of V₅Si₃ nanotubes and nanowires. When the downstream temperature is fixed at 950 °C, V₅Si₃ nanotubes are formed with the reaction time of 5 min and V₅Si ₃ nanowires are obtained with the reaction time of 15 min. With the downstream temperature of 950 °C and the reaction time of 15 min, when Si powder is mixed with carbon powder to the Si composition of 10-50%, both nanotubes and nanowires are simultaneously formed on the vanadium foil along the temperature gradient. Single-crystalline V₅Si₃ nanotubes thus synthesized are the first metal silicide nanotubes reported so far.