<p> The combined capabilities of alpha-particle emitting isotopic excitation sources and modern semiconductor detectors are investigated with a view to extending the light-element range of radioisotope-based X-ray emission analysis.</p> <p> The construction and performance of a windowless low-energy X-ray spectrometer designed around a lithium-drifted silicon detector and a 210Po source are discussed. It is shown that under the conditions used low-energy X-ray emission and detection are greatly favoured.</p> <p> Measurements of relative cross-sections for the production of X-rays by ~5.2 MeV alpha-particles in elements from oxygen to iron are reported. The results for elements of Z>16 are in good agreement with those predicted from the scaling of equal velocity proton values but show large positive deviations for elements of Z<16.</p> <p> Investigative applications of the spectrometer to quantitative analyses of blast-furnace slags, iron ores and silicate rocks for oxygen, silicon, sulpher, calcium and iron are described.</p> <p> The future prospects of radioisotopic alpha-particle X-ray excitation methods are surveyed.</p> / Thesis / Doctor of Philosophy (PhD)

<p> The mineral eudialyte from Seal Lake, Labrador, was analyzed by means of x-ray fluorescence analysis for the rare earths La, Ce, Pr, Nd, Sm, Gd, Y and also for the element Zr. Samples were prepared by two methods: a) whole mineral powder being compressed into pellets, and b) the dissolved mineral being put through an ionic exchange process to eliminate interfering ions before compressing into pellets for analysis. The results are compared with published data.on other eudialyte occurrences. </p> / Thesis / Bachelor of Science (BSc)

<p> The crystal structures of four compounds of the type (Zn,Cd,Mn)3(PO4)2 have been determined by X-ray diffraction methods. These structures are the high temperature (β) phase of Zn3(PO4)2, the related structures of β1-Mn3(PO4)2 and β1-Cd3(PO4)2, and the structure of a member of a solid solution of median composition Zn2Cd(PO4)2 which is similar in structure to the mineral graftonite. The orthophosphates of the small divalent metal ions have been separated into four structure classes and the stability of each of these classes is discussed in terms of cation concentration and the types of cation sites which exist in these structures. The correlation of a host crystal structure and the luminescence of Mn++ when this ion is added as an impurity is also discussed.</p> / Thesis / Doctor of Philosophy (PhD)

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Methanation of CO2, a greenhouse gas component, using bimetallic catalysts is considered. Rh, Pd and Ru were combined separately with Co on silica support to form bimetallic catalysts with 5 % metal loading and atomic ratio to Co equal to 1. Pore volume of the silica was measured using physisorption analysis. The unreduced catalyst samples were characterized using XPS, TPR and SEM-EDS. XPS results showed low Rh, Pd, Ru and Co concentrations at the surface for the three bimetallic catalysts. The oxidation states of metals detected by XPS supported the likely presence of metals in their oxide form. Detection of alloys and/or bimetallic particles on the surface of the catalysts was difficult through the XPS results, but presence of bimetallic particles was confirmed in Ru-Co and Pd-Co catalysts through the TPR results. Surface segregation of cobalt was observed. This was supported and extended to other metals through the SEM-EDS results.

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