Investigations of nanostructures of BN,BCN and other inorganic materials

Abstract

The thesis consists of seven chapters, of which the first chapter presents a brief overview of nanomaterials. Chapter 2 deals with the transformations of elemental nanowires of metals and silicon to nanotubes of the corresponding oxides and chalcogenides through Kirkendall effect. The study includes aspects related to the mechanism and the kinetics of the nanowirenanotube transformation. Synthesis and characterization of Al2O3, MoO3 and ZnO nanorod brushes using amorphous carbon nanotubes as templates are discussed in Chapter 3. In Chapter 4, synthesis, characterization and properties of homogeneous BC4N nanotube brushes and mesoporous microspheres are discussed. Both nanotubes and microspheres of BC4N are stable up to 900 °C and exhibit selective uptake of CO2. Chapter 5 describes the synthesis, characterization and properties of graphene analogues of BCN. Graphene analogues of BCN exhibit higher electrical resistivity than graphene, but weaker magnetic features. They are microporous exhibiting large surface area and high propensity for CO2 uptake. Chapter 6 deals with the synthesis, characterization and properties of BN nanostructures. Single- and few-layer graphene analogues of BN have been prepared by reacting boric acid with different proportions of urea. The surface area of graphene-like BN increases with the decreasing number of layers. Mechanical properties of composites of polymethylmethacrylate with graphene-like BN have also been investigated. Improvement in mechanical properties is favored by smaller number of BN layers. This chapter also describes generation of nanopans and nanosheets of graphene-like BN by the vapor phase reaction of NH3 and BBr3. Chapter 7 presents the multiferroic and magnetoelectric properties of core-shell CoFe2O4@BaTiO3 nanostructures. These core-shell nanotubes exhibit 4.7% magnetocapacitance at 310 K.