Arc Synthesis of Boron Nitride Nanotubes

We present recent results on stable and reliable synthesis of boron nitride nanotubes (BNNTs) in volume by an anodic arc discharge at near atmospheric pressure of nitrogen. This arc was operated with the boron-rich anode and the cathode made from a refractory metal which has a melting temperature above the melting point of boron. Ex-situ characterization of synthesized BNNTs with electron microscopy and Raman spectroscopy revealed that independent of the cathode material, the tubes are primarily single and double walled. Ex situ anlysis results also show evidence of root-growth of BNNTs produced in the arc discharge. In order to understand nanostructure formation we needed to determine the plasma and gas composition conditions in the nucleation and growth region. We determined plasma parameters in the growth region using plasma diagnostics and thermodynamic modelling. Previous atomistic simulations helped to analyse crucial processes in nanomaterial synthesis. References are available at nano.pppl.gov