A co-precipitation and annealing route to the large-quantity synthesis of boron nitride nanotubes

A novel co-precipitation and annealing route to the large-quantity synthesis of boron nitride nanotubes (BNNTs), using amorphous boron powder, iron nitrate nonahydrate (Fe(NO3)(3)center dot 9H(2)O) and urea (CO(NH2)(2)) as the raw materials, was demonstrated. An intermediate Fe(OH)(3)center dot B was firstly prepared through a co-precipitation process and then annealed in flowing ammonia atmosphere at 1200 degrees C. It was found that the heat treatment at 800 degrees C during the annealing process could favor the growth of BNNTs. The BNNTs had an average diameter of 70 nm and possessed bamboo and quasi-cylindrical structures. The annealing temperature greatly affected the formation of BNNTs. Only BN particles could be obtained at lower temperature (e.g. 1100 degrees C), whereas thorn-like nanosheet-decorated BNNTs were fabricated at higher temperature (e.g. 1300 degrees C). A combination mechanism of solid-liquid-solid (SLS) and vapor-liquid-solid (VLS) model was suggested to be responsible for the growth of BNNTs. (C) 2013 Elsevier Masson SAS. All rights reserved.