Hybrid organic-inorganic layered electronic materials : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Physics at Massey University, Manawatu campus, New Zealand

Abstract

Hybrid organic-inorganic materials combine distinct features of organic and inorganic components into single molecular frameworks that exhibit tunable electronic, optical and magnetic properties. An extending layered network is formed by covalently bound layers of inorganic materials that are electronically coupled by organic components. A control on the stacking orientation of these layers can help tailor the structural, physical and chemical properties of resulting compounds. This thesis presents an investigation of the synthesis, characterization and effects of doping, primarily by ion-implantation, on structural, chemical and physical properties of transition-metal oxide based organic-inorganic hybrid materials. These materials were synthesized and characterized by a variety of experimental techniques. The crystal structures of these compounds were probed by powder and single-crystal X-ray diffraction while various other techniques such as Raman spectroscopy, X-ray photoelectron spectroscopy, magnetic and resistivity measurements were applied to examine the chemical and physical properties of these materials. The crystal structure of these materials consists of infinite layers of transition metal oxides interlinked by organic ligands. The organic-ligands are aligned so as to define small cages within these structures, potentially, to accommodate metal ions. Intercalation of alkali-metal atoms within these cages brings about important altercations in the structural, chemical and physical properties of these materials. The presence of intercalated species was confirmed by single-crystal X-ray diffraction and X-ray photoelectron spectroscopy while spectral changes observed from Raman measurements and a significant reduction in electrical resistance of implanted materials refer to charge carrierinjection into the conduction band. Significant changes in structure and physical properties of these materials were observed by increasing the number of atoms in ligand tethers while introduction of additional metal atoms, by in-situ doping, in the inorganic oxide layers, leads to strong antiferromagnetic interactions in otherwise diamagnetic materials. These results demonstrate the possibilities of exploiting the self-assembly of organic and inorganic precursors to realize the potential applications these materials have to offer.