Low-temperature synthesis and growth of hexagonal boron-nitride in a lithium bromide melt

The synthesis and growth of hexagonal boron-nitride crystallites at low temperature were investigated by carrying out in a lithium bromide (LiBr) melt in 600 degrees-700 degrees C. Transmission electron microscopy study showed that the product obtained at 650 degrees C was composed of two-dimensional plates having an average thickness of about 80 nm and widths from about 400 nm to several micrometers. The molten salt was found to have a strong effect on the crystal growth. The morphology of the crystallites changed from spherical particles to two-dimensional plates when LiBr was used as a crystallization medium. Products were also characterized by X-ray powder diffractions, Fourier Transformed infrared, FESEM/energy dispersive X-ray spectroscopy, and selected area electron diffraction. Possible formation mechanism was also discussed.