Boron And Nitrogen Controllable Preparation And Properties Of Nanometer Composite Material Research

Boron nitride （BN） is an important inorganic no-metallic material which have thesimilar structure. It has the promise for the device in the future with its excellentphysical and chemical properties. In this work, the h-BN-FeB₄9nanocomposites and BNsheets have been synthesized, and characterized by PL. Meanwhile, a novel BN-coatednanorod/ZnO composite nanomaterial has been synthesized with the treated BN-coatednanorod and Zn （NO3）2and measured the gas sensing to the NO_x. Thesis includes threeparts as followed:1. Novel FeB₄9nanorods homogeneously coated with protective boron nitride sheaths（h-BN-FeB₄9nanocomposites） have been synthesized through a simple chemical vapordeposition （CVD） method at1200oCby controlling the ratio of boron/iron trioxide andthe heating rate. Detailed electron microscopy studies reveal two kinds of h-BN-FeB₄9nanocomposites with different structures and morphologies: one is a sandwich-typestructure named BN-FeB-10[B: Fe2O3=10] which is constructed by filling FeB₄9nanorods along the growth axes of closed end BN nanotubes; the other is aheterogeneous structure named BN-FeB-5[B: Fe2O3=5] in which FeB₄9is coated byh-BN sheets with4-20layers uniformly, and the h-BN sheets could be exfoliated fromBN-FeB-5using chemical exfoliation with the solvent DMF. The photoluminescence（PL） spectrum shows that the as-prepared products with these special structures havestrong emissions in the visible light region. Magnetic measurements show that bothkinds of h-BN-FeB₄9nanocomposites are hard magnetic materials at room temperature.The growth mechanism and morphology of h-BN-FeB₄9nanocomposites are discussedon the basis of the nitridation process.2. The two dimension （2D） BN nanosheets have been synthesized though the chemicalvapor deposition （CVD） method. And the different structure of the BN nanosheets havebeen synthesized with the controlling the different temperature and the catalyst.Detailed electron microscopy studies the morphologies of the samples. Thephotoluminescence （PL） spectrum shows that the as-prepared products with thesespecial structures have strong emissions. In addition, the BN-coated nanorod/ZnOcomposite nanomaterial has been synthesized. And it also has the PL emissions. 3. A novel BN-coated nanorod/ZnO composite nanomaterial has been synthesized withthe treated BN-coated nanorod and Zn （NO3）2. The TEM images reveal that thediameter of the ZnO nanoparticles is about10nm and embedded on the surface of theBN-coated nanorod successfully. That will increase the surface-to-volume ratio andenhance the electrical conductivity of the sample to promote the senses of the NO_x. Thegas sensing measure exhibited that the BN-coated nanorod/ZnO composite have aperfect sensing performances compare to the bare BN-coated nanorod and ZnO.Meanwhile, the composite have the better sensitivity response to NO_xat the roomtemperature conditions. The possible gas sensing mechanism of the BN-coatednanorod/ZnO composite is explained by model in which effect of NO_xadsorption onZnO nanoparticles and electronic transport properties are discussed based on theexperimental results.