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Studies have been made of the subsolidus phase distribution in the CaO-rich positions of the system CaO-Al2O3-SiO2-CaSO4-K2SO4. These have been made using classical methods of phase equilibrium investigations. The nature of the solid phases were determined principally by powder X-ray diffraction. The results are presented as a series of phase diagrams depicting the equilibria. Some data were also obtained on the effect of iron oxide, added as 4CaO Fe2O3Al2O3, on the equilibria. The results can be used to predict- the solid-phase assemblages which will occur at equilibrium in a Portland cement kiln operating under oxidizing conditions. It has also been shown that the phase hitherto regarded as anhydrous Ca5 Si2SO12 contains essential water. The effects of F- and Ct- in the sulphate equilibria have also been determined by studying the systems Ca10 (PO4) 6F2-Ca10 (PO4)6Cl2-Ca5(SiO4) (PO4) 2; Ca10 (SiO4)3 (SO4) F2-Ca10(SiO4)3(SO4)3Cl2-Ca5(SiO4)2SO4.Some data were also obtained on the temperature and composition of eutectic sulphate melts; these confirm that extensive liquid immiscibility occurs between sulphate and silicate melts.

This thesis probes three technologically important metal-oxide systems; Pd nanoparticles supported on the TiO2(110) surface, acetate on TiO2(110) and Fe3O4(111). The orientation of CO adsorbed to a Pd/TiO2(110) model catalyst system was probed using X-ray photoemission electron microscopy (XPEEM) and near-edge X-ray absorption fine structure (NEXAFS). The absorbed CO molecules were found to have an off-normal polar orientation, relative to the basal plane of the substrate. The result was interpreted as an average of several sets of CO molecules absorbed and oriented orthogonally to various facets of the Pd nanoparticles, some of the facets themselves orientated with an angular separation from the basal plane. The acetate saturated TiO2(110) surface was examined using photoelectron spectroscopy (PES) and NEXAFS under UHV conditions as well as under increased pressures of acetic acid. The coverage and orientation of the adsorbed acetic acid were studied. It was found that a second 0.5 ML of acetate, additional to the half-monolayer film observed in UHV, develops under 0.01 Torr of acetic acid pressure. This second layer is thought to be hydrogen bonded to hydroxyl groups that are formed during the absorption of the first layer. Additionally, the 1st half-monolayer is shown to be slightly tilted, this is believed to be the effect of hydroxyls and to influence the tilt of the second layer. Structural characterisation work was carried out on the Fe3O4(111) single-crystal surface with low energy electron diffraction. Full characterisation was not possible due to incomplete experimental data, however, a novel version of the analysis software CLEED was developed to accommodate simultaneous mutliple domain analysis.

A brief outline has been given of the present knowledge of the kinetics of the thermal decomposition of inorganic solids. The iso¬ thermal decomposition of potassium metaperiodate crystals, which were 300 u and 40 u in linear dimensions, has ueen studied, together with the effects on the subsequent decomposition, of storage and preirradiation with ultraviolet light.

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