Transition metal oxide thin films are commonly used in organic electronics devices to improve charge-injection between electrodes and organic semiconductors. Some oxides are good hole-injectors, while others are good electron-injectors. Transition metal oxides are materials with many diverse properties. Many transition metals have more than one stable oxidation state and can form more than one oxide. Each oxide possesses its own unique properties. For example, transition metal oxide electronic band structures can range from insulating to conducting. They can exhibit a wide range of work functions. Some oxides are inert, while others are catalytically active. Such properties are affected by numerous factors, including cation oxidation state and multiple types of defects. Currently it is not fully understood which oxide properties are the most important to their performance in organic electronics. In the present thesis, photoemission spectroscopy is used to examine how changes in certain oxide properties–such as cation oxidation states and defects—are linked to the oxide properties that are relevant to organic electronics devices—such as an oxide’s work function and electron band structure. In order to unravel correlations between these properties, we controllably change one property and measure how it changes affects another property. By performing such tests on a wide range of diverse transition metal oxides, we can discern broadly-applicable relationships. We establish a relationship between cation oxidation state, work functions and valence band structures. We determine that an oxide’s electron chemical potential relative to an organic’s donor and acceptor levels governs energy-level alignment at oxide organic interfaces. We establish how interfacial reactivity at electrode/oxide interfaces dictates an oxide’s work function and electronic structure near the interface. iii These findings demonstrate some of the very interesting fundamental relationships that exist between chemical and electronic properties at interfaces. These findings should assist in the future development and understanding of the functional interfaces of organic semiconductors and transition-metal oxides.

Iron oxyhydroxides are ubiquitous in surface environments, playing a key role in many biogeochemical processes. Their characterization is made challenging by their nanophase nature. Magnetometry serves as a sensitive non-destructive characterization technique that can elucidate intrinsic physical properties, taking advantage of the superparamagnetic behaviour that nanoparticles may exhibit. In this work, synthetic analogues of common iron oxyhydroxide minerals (ferrihydrite, goethite, lepidocrocite, schwertmannite and akaganéite) are characterized using DC and AC magnetometry (cryogenic, room temperature), along with complementary analyses from Mössbauer spectroscopy (cryogenic, room temperature), powder X-ray diffraction and scanning electron microscopy. It was found that all of the iron oxyhydroxide mineral nanoparticles, including lepidocrocite, schwertmannite and akaganéite were superparamagnetic and therefore magnetically ordered at room temperature. Previous estimates of Néel temperatures for these three minerals are relatively low and are understood as misinterpreted magnetic blocking temperatures. This has important implications in environmental geoscience due to this mineral group’s potential as magnetic remanence carriers. Analysis of the data enabled the extraction of the intrinsic physical parameters of the nanoparticles, including magnetic sizes. The study also showed the possible effect on these parameters of crystal-chemical variations, due to elemental structural incorporation, providing a nanoscale mineralogical characterization of these iron oxyhydroxides. The analysis of the intrinsic parameters showed that all of the iron oxyhydroxide mineral nanoparticles considered here have a common magnetic moment formation mechanism associated with a random spatial distribution of iv uncompensated magnetic spins, and with different degrees of structural disorder and compositional stoichiometry variability, which give rise to relatively large intrinsic magnetization values. The elucidation of the magnetic nanostructure also contributes to the study of the surface region of the nanoparticles, which affects the particles’ reactivity in the environment.

The crystallographic and magnetic properties of manganese oxides belonging to the Ruddlesden Popper (RP) series, described by the formula A_n+1B_nO_3n+1, are presented. Compounds having n = 2, 3 and ∞ are discussed in Chapters 3, 4 and 5, respectively, their properties being studied by powder X-ray and neutron diffraction, SQUID magnetometry and magnetotransport measurements. In Chapter 3 (A₃B₂O₇) it is shown that Sr_2-xNd_1+xMn₂O₇ (0 ≤ x ≤ 0.5) and Sr₂PrMn₂O₇ exhibit colossal, negative magnetoresistance (CMR) below 150K. The zero field resistivity signal is reduced by 2-3 orders of magnitude in a field of 14T, at ~4.2K. The compounds Sr₂HoMn₂O₇ and Sr₂YMn₂O₇ show no significant magnetoresistance. In contrast to the tetragonal Sr,Nd and Sr,Pr compositions, these compounds show a symmetry lowering to space group P4₂/mnm, and spin glass freezing on the Mn sublattice at ~20K. Chapter 4 (A₄B₃O₁₀) focuses on A- and B-cation substitutions in the parent compound Ca₄Mn₃O_10-δ. Substitution of Ca by Sr yields Sr₄Mn₃O_10-δ, an orthorhombic (Cmca) compound, composed of trimers of face sharing octahedra. The magnetic susceptibility of this sample is interpreted in terms of direct and indirect antiferromagnetic (AFM) Mn-Mn exchange interactions. The orthorhombic (Pbca) RP phase Ca_3.95La_0.05Mn₃O_10-δ has a magnetic transition at ~114K, suggesting that the antiferromagnetic groundstate, with associated weak ferromagnetism arising through the Dzyaloshinsky-Moriya interaction observed in Ca₄Mn₃O_10-δ, is preserved on introduction of a fraction of La³⁺ dopant cations. Ca_3.95La_0.05Mn₃O_10-δ displays CMR at 4K, with the resistivity signal reduced to 18% of the zero field value, in 14T. B-cation substitution yields Ca₄Mn₂TiO_9.93, an orthorhombic (Pbca) RP phase in which the Mn:Ti cation distribution, deduced from the combined results of anomalous dispersion X-ray experiments and neutron diffraction studies, is 59.8%(2.6):40.2%(2.6) and 70.1%(1.3):29.9%(1.3) across the 4b and 8c octahedral sites, respectively. Neutron diffraction studies at 5K show the presence of only short range magnetic interactions in this insulating material, the resistivity of which is reduced by just 10% at 75K in 14T. Chapter 5 (ABO₃ or A₂BB'O₆) describes the mixed B-cation phases, La₂GaMnO₆ and Nd₂GaMnO₆, containing Mn³⁺, 3d⁴ cations. Both are cation disordered, orthorhombic (Pnma) materials, and Nd₂GaMnO₆ exhibits a static, cooperative Jahn-Teller (JT) distortion. La₂GaMnO₆ contains a relatively higher proportion of dynamic, cooperative JT distortions, and as such exhibits isotropic ferromagnetism at 5OK and 5K (2.80(5)μ_B per Mn aligned along y at 5K), predicted by the 'quasistatic hypothesis', which describes the correlation between electron spin configurations of neighbouring JT cations. The magnetic structure of Nd₂GaMnO₆ at 5K and 1.7K is modelled as 'A_X F_Y G_Z' for the Mn sublattice, and 'F_γ' for the Nd sublattice, using Bertaut's notation, resulting in competing ferromagnetic and antiferromagnetic superexchange interactions on the Mn sublattice along the [010] direction of the unit cell. Both materials are highly insulating and neither displays CMR, with resistivity values in each being reduced to just 96% of the zero field value at 200K, in a field of 14T.

This thesis is divided into two parts. The first part concerns the synthesis and characterisation of substituted metallocene complexes of the transition and main group metals. The second part describes the preparation and characterisation of inorganic fullerene (IF)-related materials. <strong>Chapter 1</strong> reviews the chemistry of dialkyl- and diaryl-phosphino substituted cyclopentadienyl complexes of the transition metals. <strong>Chapter 2</strong> describes the synthesis and characterisation of the new ligands [M(C₅Me₄)CH₂PMe₂] (M = H, Li, Na and K) via the precursors [HC₅Me₄)CH₂PHMe₂][X] (X = Cl and PF₆). The synthesis, characterisation and chemical reactivity of the compounds [Zr{{η-C₅Me₄)CH₂PMe₂}₂Cl₂ and [Mn{η-C₅Me₄)CH₂PMe₂}₂] is reported together with supporting evidence for the synthesis of the bimetallic complex [Zr{U+03B7-C₅Me₄)CH₂PMe₂}₂Cl₂PtI₂] and the complex [Mn{η-C₅Me₄)CH₂PMe₂B(C₆F₅)₃}₂]. <strong>Chapter 3</strong> provides a brief introduction into the field of main group metallocenes and describes the synthesis and characterisation of the new main group metallocenes [M{η- C₅H₄)CMe₂PMe₂}₂] (M = Pb and Sn). The B(C₆F₅)<sub>3 adduct [Pb{η-C₅H₄)CMe₂PMe₂(B(C₆F₅)₃}₂] has also been synthesised. The main group - transition metal bimetallic complex [Pb{η-C₅H₄)CMe₂PMe₂}₂PtI<sub>2<sub> in which the substitutedplumbocene acts as a bidentate ligand, has been characterised by mass spectrometry and ³¹P{¹H}NMR spectroscopy. <strong>Chapter 4</strong> provides an introduction into the field of IF-related materials and an overview of the analytical techniques used in their characterisation. <strong>Chapter 5</strong> describes the preparation and characterisation of IF-MoS₂ and IF-(Nb,W)S₂ materials from MoC and the binary oxides Nb₈ W₉O₄₇ and Nb₄W₁₃O₄₇ respectively. A powder X-ray diffraction study of the conversion of WC to WO_3-X and the subsequent sulfidisation by H₂S to form novel IF-WS₂ morphologies is also described. <strong>Chapter 6</strong> describes the preparation of amorphous Group 5 metal (V, Nb and Ta) oxides using the metal vapour synthesis technique. These amorphous precursors have been annealed in a reducing atmosphere to form the oxide phases U+03B1-V₂O₃, NbO₂ and TT-Ta₂O₅ which have been identified by powder X-ray diffraction. Upon reaction with H₂S, the crystalline oxides afford layered sulfides of the form MS₂ (M = V, Nb and Ta), some of which exhibit behaviour typical of IF-like materials and have been characterised by HRTEM, powder X-ray diffraction and EDX analysis. Chapter 7 outlines the experimental details for the synthesis, characterisation, reactions and compounds described in the preceding chapters. <strong>Chapter 8</strong> presents the characterising data for the new compounds described in chapters 2 and 3. <strong>Appendix A</strong> contains details of the crystallographic data for the structurally characterised compound [Mn{η-C₅Me₄)CH<sub>PMe₂}₂].

Transparent conducting oxides (TCOs) usually have high conductivity and transparency in the visible range and have been widely used in daily life. Recently, TCOs have attracted great interest due to their potential applications in various new optical and electrical devices (flat-panel displays, energy efficient windows, etc.). Nanostructured TCOs can induce new size related properties, for example, when sizes of TCOs are controlled at the nanometer scale, various defects can introduce different defect-related optical emissions. These new nanostructured TCOs combining traditional and new size dependent properties may be used for construction of next generation optical devices. To investigate the optical properties of TCOs at nanoscale, in this thesis, several new kinds of colloidal nanocrystals (NCs) of TCOs have been synthesized and their optical emission and transparency have been explored. The first part of my work focuses on ITO (indium tin oxide) NCs demonstrates phase and size dependence of surface plasmon absorption in the near infrared region. The second part of the thesis describes colloidal synthesis of γ-Ga2O3 with size tunable photoluminescence, further study reveals that the photoluminescence is defect related and can be tuned by changing the defect concentration. In the last part of my study, I develop a methodology for lanthanide doped γ-phase Ga2O3 NCs and reveal tunable chromaticity of the lanthanide doped NCs.

Transparent conducting oxides (TCOs) usually have high conductivity and transparency in the visible range and have been widely used in daily life. Recently, TCOs have attracted great interest due to their potential applications in various new optical and electrical devices (flat-panel displays, energy efficient windows, etc.). Nanostructured TCOs can induce new size related properties, for example, when sizes of TCOs are controlled at the nanometer scale, various defects can introduce different defect-related optical emissions. These new nanostructured TCOs combining traditional and new size dependent properties may be used for construction of next generation optical devices. To investigate the optical properties of TCOs at nanoscale, in this thesis, several new kinds of colloidal nanocrystals (NCs) of TCOs have been synthesized and their optical emission and transparency have been explored. The first part of my work focuses on ITO (indium tin oxide) NCs demonstrates phase and size dependence of surface plasmon absorption in the near infrared region. The second part of the thesis describes colloidal synthesis of γ-Ga2O3 with size tunable photoluminescence, further study reveals that the photoluminescence is defect related and can be tuned by changing the defect concentration. In the last part of my study, I develop a methodology for lanthanide doped γ-phase Ga2O3 NCs and reveal tunable chromaticity of the lanthanide doped NCs.

Thesis (Ph. D.)--University of Hawaii at Manoa, 1995. / Includes bibliographical references. / Microfiche. / xxi, 170 leaves, bound ill. 29 cm

In order to clarify the role that water plays in the photocatalytic process, changes in the IR and Raman spectra of P25 TiO₂ thin films were observed upon exposure to liquid water. Further investigation of these spectral changes via dehydration of thin films under nitrogen and oxygen of different humidities led to the observation of spectroscopic features that have been assigned to localised surface phonon modes. When the effect of UV irradiation on these features was investigated, a broad IR absorption due to transitions of electrons in shallow traps was detected under dry nitrogen but not under dry oxygen. Further investigation of the photocatalytic properties of P25 TiO₂ showed a complete removal of a stearic acid film. The final products have been tentatively assigned to a mixture of short chain carbonyl species and adsorbed carbonates as well as carbon dioxide and water. The IR spectrum of the fuel cell membrane material Nafion is complex and literature data varies in some of the assignments. The compound perfluoro(2-ethoxyethane)sulfonic acid was used as a model compound for the Nafion side chain resulting in a clearer assignment of the Nafion IR spectrum. In light of these new assignments changes induced in the region 1100-1300 cm⁻� by variation in humidity and ion exchange have been shown to be mainly the result of changes in the sulfonate asymmetric stretching modes. By flowing a series of solutions containing tetramethylammonium ions and perchlorate ions the surface charge characteristics of a Pt black film were determined in the pH range 2-12. There proved to be a weak positive charge below pH 4 and a weak negative charge above pH 9. Between these points there appeared to be no overall charge on the surface. When perfluoro(2-ethoxyethane)sulfonic acid was adsorbed to a Pt black film changes in its IR spectrum indicated a strong binding via interactions between the sulfonate groups and the Pt surface. The nature of the adsorption of Nafion was less clear cut and, whilst adsorption is strong, it seems possible that hydrophobic interactions between the Nafion backbone and the surface are involved.

Bibliography: leaves 244-259. / xxii, 259 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Copper loaded Australian natural zeolites and ZSM-5 zeolites were investigated for the selective catalytic reduction of nitrogen oxides using CH4 and C3h6 with the specific aims of investigating natural zeolite as an alternative support to ZSM-5, determining a rate law for the selective catalytic reduction of nitrogen oxides using C3h6 over Cu-ZSM-5; and, investigating the molecular scale interactions of the reaction gases with Cu-ZSM-5. / Thesis (Ph.D.)--University of Adelaide, Dept. of Chemical Engineering, 1999

[Truncated abstract] In the past decade, the synthesis of superparamagnetic iron oxide nanoparticles (SPIONs) has received considerable attention due to their potential applications in biomedical fields. However, success in size and shape control of the SPIONs has been mostly achieved through organic routes using large quantities of toxic or/and expensive precursors in organic reaction medium at high reaction temperature. This has limited the biomedical applications of SPIONs and therefore, development of a synthetic method under aqueous condition that is reproducible, scalable, environmentally benign, and economically feasible for industrial production is of paramount importance in order to fully realise their practical applications. Spinning Disc Processing (SDP) has been used to synthesise superparamagnetic magnetite (Fe3O4) nanoparticles at room temperature via a modified chemical precipitation method under continuous flow condition and offer a potential alternative to be applied to SPIONs production. SDP has extremely rapid mixing under plug flow conditions, effective heat and mass transfer, allowing high throughput with low wastage solvent efficiency. The synthesis process involves passing ammonia gas over a thin aqueous film of Fe2+/3+ which is introduced through a jet feed close to the centre of a rapidly rotating disc (500-2500 rpm). Synthetic parameters such as precursor concentrations, temperature, flow rate, disc speed, and surface texture influence the particle sizes. ... Magnetic silica microspheres are receiving great attention for possible applications in magnetic targeting drug delivery, bioseparation and enzyme isolation. However, the current available methods for preparation suffer from the setback of low loading of Fe3O4 nanoparticles in the silica microsphere, which result in low magnetic moment, thereby limiting their practical applications. Therefore it is of considerable importance to develop new alternative synthetic methods for fabricating magnetic silica microspheres with high magnetic nanoparticles loading. Superparamagentic Fe3O4 nanoparticles (8-10 nm diameter) and curcumin have been encapsulated in mesoporous silica in a simple multiplestep self assembly approach process with high Fe3O4 nanoparticles loading (37%). The synthesis involves loading of curcumin in the Cetyltrimethylammonium bromide (CTAB) micellar rod in the presence of superparamagnetic Fe3O4 nanoparticles via a parallel synergistic approach. The synthesised magnetic mesoporous silica composite material is stable, superparamagnetic with high saturation magnetisation before and after curcumin leaching experiment. Under physiological pH in phosphate buffer, the curcumin is slowly released over several days. These magnetic mesoporous silica are expected to have great potential as targeted drug delivery systems.