Contributions to the chemistry of metal nitrides and inorganic nanomaterials

Abstract

This thesis consists of three parts. In Part 1 of the thesis, a simple and novel method for the synthesis of metal nitrides and oxynitrides in which urea is used as the nitrogen source is described. The various binary nitrides prepared by the reaction of urea with metal halides and metal oxides are BN, TiN, NbN, γ-Mo2N and δ-MoN. The ternary nitrides prepared by heating metal molybdates with urea are Fe3Mo3N, Co3Mo3N and Ni2Mo3N. The oxynitrides prepared by the heat treatment of alkaline earth carbonates and metal oxides with urea are CaTaO2N, SrTaO2N, BaTaO2N, SrNbO2N, BaNbO2N, LaTaON2, LaTiO2N and SrMoO3-xNx. All these materials have been characterized appropriately. The urea route has been used to coat carbon fibers and other one-dimensional inorganic nanostructures with ceramic BN. Part 2 of the thesis deals with the functionalization and solubilization of inorganic nanomaterials such as nanoparticles of CeO2, Fe3O4 TiO2, ZnO, Fe2O3, BN and GaN, nanowires of TiO2, ZnO and Al2O3 and carbon nanotubes. The strategies employed for the functionalization includes use of the surfactants and interaction with organosilane or organotin reagents. The functionalized-materials were suitably characterized. Using polyoctasilsesquioxane (POSS)-functionalized inorganic nanoparticles, composites of polymers have been prepared and characterized. Part 3 describes the investigation of two-dimensional graphene-like WS2. The methods used to synthesize inorganic graphene analogues of WS2 are to intercalate bulk WS2 with lithium followed by exfoliation in water and by heating tungstic acid with thiourea in a nitrogen atmosphere. Few-layer WS2 was characterized by using atomic force microscopy, Raman spectroscopy and other techniques.