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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°–700°C. Transmission electron microscopy study showed that the product obtained at 650°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. [ABSTRACT FROM AUTHOR]

A novel boron nitride nanotube‐supported nano‐sheets one‐dimensional hierarchical structures (BNNT‐BNNS) were efficiently prepared via a ball milling assisting chemical vapor deposition method. X‐ray powder diffraction (XRD), fourier transform infrared spectrometer (FTIR), Raman, field scanning electron microscopy (FSEM), energy dispersive spectroscopy (EDX), transmission electron microscopy (TEM) and high‐resolution transmission electron microscopy (HRTEM) were used to characterize the as‐synthesized samples. The samples presented a length of more than 20 μm and wide diameter ranges from 20 nm to 600 nm. Abundant nano‐sheets grew in random directions and intertwined closely on the surface of the one‐dimensional structures. Every nano‐sheet was transparent and demonstrated a thickness of less than 10 nm with irregular size and shape. Ultraviolet‐visible (UV‐vis) and photoluminescence (PL) results indicated that the band gap was 5.71 eV and the maximum fluorescence emission peak was located at 368 nm. In addition, it was worth noting that the BNNT‐BNNS hierarchical structures also presented excellent adsorption property for methylene blue (MB). When the adsorption time was 5 min, MB could be removed by 75.2% from water solution. The adsorption rate could increase to 97.3% when the adsorption time was 115 min. Finally, the possible chemical reactions and the corresponding catalytic cracking growth mechanism of the special hierarchical structures also were investigated carefully. One‐dimensional boron nitride nanotube‐supported nano‐sheets hierarchical structures (BNNT‐BNNS) were prepared by a ball milling assisting chemical vapor deposition method. The band gap was 5.71 eV and the maximum fluorescence emission peak was located at 368 nm. MB could be removed by 75.2% when the adsorption time was 5 min. Possible chemical reactions and catalytic cracking growth mechanism of the samples were also proposed. [ABSTRACT FROM AUTHOR]

α-silicon nitride nanorods have been synthesized through solid-state reduction–nitridation of silica using NaNH2 as both a reductant and a nitriding reagent. X-ray powder diffraction patterns show that the products have a hexagonal phase with lattice parameters a=7.767 Å and c=5.630 Å. Transmission electron microscopy reveals that the as-synthesized products are pure nanorods with an average size about 30 nm in diameter and 400 nm in length. X-ray photoelectron spectra indicate that the molar ratio of Si/N is 2.988:4. Fourier-transform infrared spectrum yields a strong Si–N absorption at 926 cm−1 that may be a red shift due to size effect. [ABSTRACT FROM AUTHOR]