Structures and purification of boron nitride nanotubes synthesized from boron-based powders with iron particles

Boron nitride (BN) nanotubes, nanohorns and nanocoils were synthesized by annealing Fe₄N/B, FeB and Fe/B powders at 1000 °C for 1–24 h in nitrogen gas atmosphere, and large amounts of BN nanotubes were obtained by annealing Fe₄N/B. The growth mechanism and atomic structures were investigated on cup-stacked BN nanotubes synthesized from Fe₄N/B by X-ray diffraction, high-resolution electron microscopy, electron diffraction and energy dispersive X-ray spectroscopy. As-produced BN soot was purified by removing non-BN nanomaterials such as metal catalyst particles and unreacted boron, and high purity BN nanotubes were obtained.