Synthesis, Characterization And Growth Mechanism Of Boron Nitride And Boron Carbonitride Nanotubes

In this paper, we have reviewed about the research progress on structure, properties and preparation methods of BN nanotubes and BCN nanotubes in recently. A novel and simple method including co-precipitation and high temperature reaction is developed to synthesize BN nanotubes, and a sol-gel method in different catalyst contents and varieties is firstly demonstrated to synthesize BCN nanotubes. The obtained products were characterized by Furrier transform infrared (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and X-ray energy dispersive spectrometer (EDX). And the growth mechanisms of BN and BCN nanotubes were also investigated.In this study, a large quantity synthesis of BN nanotubes via two processes of co-precipitation and annealing reaction was demonstrated, by using amorphous boron powders, iron nitrate nonahydrate and urea as raw materials. The analysis results show that the synthesized nanotubes with an average diameter of about70nm exhibit two types, including bamboo structure with the thickness of the compartment layer is similar to the wall and quasi-cylindrical structure which the compartment layer is thinner than the wall. Meanwhile, the influencing factors which effect on the morphology, partical size and yield of the nanotubes including temperature, catalyst contents, gas flow rate and so on were also discussion. It is found that the diameter of the nanotubes increased with the temperature lifted. When the temperature became too high, thorn-like nanosheet-decorated BN nanotubes with thick diameter were produced. There were little nanotubes obtained when the catalyst content was lower. While the catalyst content was too higher, rough nanotubes with large diameter were synthesized. The nanotubes grow via a combination mechanism of vapor-liquid-solid (VLS) and solid-liquid-solid (SLS) models.The synthesis of BCN nanotubes via Sol-Gel method in different catalyst condition was firstly discussed by using vinyl alcohol (PVA-124), boric acid (H3BO3), urea (CO(NH2)2), iron nitrate nonahydrate (Fe(NO3)3·9H2O) and sodium hydroxide (NaOH) as starting materials. It was found that the yield of nanotubes increased with the catalyst content elevated. Moreover, there was no nanotubes obtained when no catalyst and equimolar iron chloride hexahydrate (FeCl3·6H2O) were instead of iron nitrate nonahydrate. Meanwhile, the effect of ball milled time of the precursor on the preparation of BCN nanotubes was also discussed. The analysis results indicated that the growth mechanism of BCN nanotubes was vapor-liquid-solid (VLS) model.