Synthesis and formation mechanism of cubic boron nitride nanorods in lithium bromide molten salt

Cubic boron nitride nanorods (cBNNRs) were synthesized through a simple reaction between boron tribromide and sodium amide in lithium bromide molten salt medium at 600 degrees C in a sealed autoclave system. The cBNNRs observed by transmission electron microscopy have various diameters ranging from 8 to 25 nm with aspect ratios of about 10-20. X-ray diffraction and selected area electron diffraction pattern revealed the cubic phase of cBNNRs with a lattice constant a=3.625 angstrom. The B:N ratio obtained by energy dispersive X-ray spectroscopy was 1:1.12, and Fourier transform infrared spectrum showed a characteristic absorption at 1106 cm(-1). The possible formation mechanism of cBNNRs in molten salt medium is also discussed. (C) 2012 Elsevier B.V. All rights reserved.