Synthesis and characterization of boron nitride nanotubes using a simple chemical method

A simple two-step process is used for the growth of high purity multiwalled boron nitride (BN) nanotubes. In the first step, disordered nanostructured BN powder (aBN) is prepared chemically by heating a powdered mixture of KBH₄ and NH₄Cl (1:1) at 850ºC in N₂ followed by quenching the reaction product. In the second step, BN nanotubes are grown from the as-prepared aBN powder by annealing it at about 1200-1300ºC for 5-10 h in N₂. No catalyst material (Fe, Ni, Co, etc.) is intentionally added to aBN powder. This method of synthesis resulted in high purity multiwalled BN nanotubes of almost uniform diameter (10-30 nm) and length up to 5 µm, and, thus has a high aspect ratio with inherent characteristics of BN nanotubes, which may be useful for different applications. The BN nanotubes have been characterized using various techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. The results obtained by this process are also compared with the similar type of BN nanotubes produced employing ball-milling and annealing technique