Solid-state reaction synthesis of boron carbonitride nanotubes

Abstract

In this study, a simple route for synthesis of ternary boron carbonitride (B–C–N) nanotubes was demonstrated, by heating ball-milled mixture powders of amorphous boron and activated charcoal with a small amount of iron oxide (Fe₂O₃) at 1000–1200°C under a mixture gas flow of nitrogen (N₂) and hydrogen (H₂). The reduction of Fe₂O₃ by H₂ at 650°C produced Fe nanoparticles, playing the role of a catalyst during the nanotube growth. The nanotubes synthesized at 1100°C exhibit two morphologies. One is a bamboo-like structure with thick compartments. The other is a quasi-cylindrical structure with thin or disappearing compartments. The average diameter of the nanotubes is about 80 nm. It is found that the reaction temperature has a great influence on the morphology, diameter and yield of the B–C–N nanotubes. Higher temperature (1200°C) is favorable for the formation of quasi-cylindrical nanotubes with larger diameters, while lower temperature (1000°C) enhances the formation of bamboo-like nanotubes with smaller diameters; the yield of nanotubes decreases with the rise of reaction temperature. The nanotubes grow via a combination mechanism of solid–liquid–solid (SLS) and vapor–liquid–solid (VLS) models.