Preparation And Properties Of Boron Nitride Nanosheets By CVD Method

One-and two-dimensional nanostructures defined as those having at least one dimension between1and100nm have attracted a prime attention over the past two decades due to their peculiar and fascinating properties and a wide range of interesting potential applications which, in many cases, shall be more fruitful than for the corresponding bulky material counterparts. The original findings of carbon nanotubes (CNTs) stimulated intense theoretical and experimental studies in regard to other nanostructures based on similar honeycomb-like networks. Layered boron nitride is a structural analogue of graphite in which alternating B and N atoms substitute for C atoms. Therefore, layered boron nitride has become a research hotspot. In this paper, one-and two-dimensional boron nitride materials and B-C-N nanotubes have been synthesized by chemical vapor deposition (CVD) method and solid state reaction. The composition, morphology and properties of the products were studied.Firstly, synthesis of vertically aligned boron nitride nanosheets (BNNSs) on silicon substrates at1000℃by chemical vapor deposition from a gas mixture of BCl3-NH3-H2, without the assistance of microwave plasma or electric field. The as-prepared BNNSs were less than10nm, with graphite analogs structure. The chemical composition and structure were studied by energy dispersive spectroscopy, X-ray photoelectron spectroscopy and Fourier transformation infrared spectroscopy. Cathodoluminescence spectra revealed that the products emitted strong UV light with a broad band ranging from250to400nm. Field-emission characteristic of the products shows a low turn-on field of6.5V μm-1Secondly, silicon nanowires were synthesized using superimposed silicones, and synthesis of BN structure on their surface using CVD method. The products on the surface of silicon nanowires have rough morphology composed of small pieces. FTIR and XPS confirm that the products were h-BN. The growth of the products is also discussed.Thirdly, B-C-N nanotubes were synthesized by solid state reaction using melamine, boric acid and nickel nitride. XRD result reveals that the B-C-N nanotubes were hexagonal phase, and containing Ni catalyst. SEM, TEM and HRTEM results showed that the diameters of the nanotubes were between30to90nm, and the length was micrometers, with bamboo-like structure. Raman and FTIR were also used to study the products.In summary, one-and two-dimensional boron nitride materials and B-C-N nanotubes have been investigated on the preparation, characterization and growth mechanism. Some important results have been obtained, and these will be beneficial to the future study.