The effect of iron oxide on the formation of boron nitride nanotubes

Abstract

Boron nitride (BN) nanotubes with different yield and structure were synthesized on stainless-steel substrates, by heating mixture powders of amorphous boron and iron oxide (Fe 2O 3) at 1300 °C in flowing ammonia atmosphere. It was found that Fe 2O 3 could affect the yield and structure of BN nanotubes dramatically through its adding amount in the starting materials. When the Fe 2O 3/B molar ratio was small, pure but low-yield BN nanotubes were obtained. Nearly no particle was observed in the product. Meanwhile, the nanotubes were generally hollow with very few B–O–Si–Mn species filled within the tube cavity or enwrapped in the walls. The yield of nanotubes obviously rose with the increase of Fe 2O 3/B ratio. However, the amounts of B–N–O–Si–Mn particles in the product (from which nanotubes grew in a radial pattern) and B–O–Si–Mn species within the cavity or the walls of the nanotubes also increased. The growth mechanism of the BN nanotubes was believed to be in the framework of vapor–liquid–solid (VLS) model.