Porous, high surface area activated carbon (AC) can be used to remove certain irritating and toxic gases from contaminated air streams. Impregnating AC with carefully selected chemicals can improve ACs adsorption capacity for certain gases and provide adsorption capacity for gases that un-impregnated AC cannot fi lter. Impregnated activated carbons (IACs) and ACs can be used as the active component in respirators. Comparative studies of di fferent commercially available AC samples and of IAC samples, prepared from a wide variety of di fferent chemicals, were performed. The gas adsorption capacity of the samples was tested using sulfur dioxide (SO2), ammonia (NH3), hydrogen cyanide (HCN) and cyclohexane (C6H12) challenge gases and compared to results obtained from a commercially available broad spectrum respirator carbon. The samples were characterized using wide angle x-ray di raction (XRD), small angle x-ray scattering (SAXS), nitrogen adsorption isotherms, thermal gravimetric analysis (TGA) and scanning electron microscopy (SEM). Highlights of this work include the discovery of a IAC sample prepared from zinc nitrate (Zn(NO3)2) and nitric acid (HNO3) that, after heating at 180 C under argon, had overall dry gas adsorption capacity that was greater than the commercially available sample. The importance of pore size on the C6H12 adsorption capacity of AC was demonstrated using SAXS and nitrogen adsorption data. A relationship between decreased humid C6H12 capacity and pre-adsorbed water was shown using SAXS, TGA and gravimetric studies.

The improvement of volumetric energy density remains a key area of research to opti-mize Li-ion batteries for applications such as extending the range of electric vehicles. There is still improvement to be made in the energy density in the positive elec-trode materials. The current thesis deals with determining the phase diagrams of the Li-Mn-Ni-O and Li-Co-Mn-O systems in order to better understand the structures and the electrochemistry of these materials. The phase diagrams were made through careful analysis of hundreds of X-ray di raction patterns taken of milligram-scale combinatorial samples. A number of bulk samples were also investigated. The Li-Mn-Ni-O system is of particular interest as avoiding cobalt lowers the cost of the material. However, this system is very complex: there are two large solid-solution regions separated by three two-phase regions as well as two three-phase regions. Comparing quenched and slow cooled samples shows that the system trans-form dramatically when cooled at rates typically used to make commercial materials. The consequences of these results are that much of the system must be avoided in order to guarantee that the materials remain single phase during cooling. This work should therefore impact signi cantly researchers working on composite electrodes. Two new structures were found. The first was Li-Ni-Mn oxide rocksalt structures with vacancies and ordering of manganese which were previously mistakenly identi ed as LixNi2xO2. The other new structure was a layered oxide with metal site vacancies allowing manganese to order on two superlattices. The electrochemistry of both these materials is presented here. Finally, the region where layered-layered composites form during cooling has been determined. These materials were long looked for along the composition line from Li2MnO3 to LiNi0.5Mn0.5O2 and the most significant consequence of the actual locations of the end-members is that one of the structures contains a high concentration of nickel on the lithium layer. Layered-layered nano-composites formed in this system are therefore not ideal positive electrode materials and it will be demonstrated that single-phase layered materials lead to better electrochemistry.

Over the last decade progress towards step-wise structural transformations in solid state chemistry has been made using metal hydride reductants. Alkali and alkali-earth metal hydrides can effectively reduce transition metal oxides resulting frequently in novel oxygen defect structures. This provides access to control over cation oxidation states and magnetic exchange pathways, and thus electronic and magnetic properties. The goal for this research was to investigate a representative system that could be used both for exploration of novel oxygen defect phases and for investigating the fundamental parameters governing successful solid state reductions. The systems chosen for investigation were Sr2-xCaxMnO4 (0<x<2) and Sr2-xBaxMnO4 (x< 0.04). Detailed analysis of metal hydride reactivity with Sr2MnO4 is presented in addition to proof of the solid state reduction mechanism. As a result a number of novel oxygen defect phases have been produced, Sr2MnO4-x (0<x<0.37). The potential for producing novel lithium doped Sr2MnO4-x phases using a reduction/insertion approach with LiH has also been identified. Lastly as a test of application for metal hydrides as reductants the ability to topotactically reduce ScVO4 has been investigated.

Cement-based materials are of importance in the construction of geothermal wells and high-temperature oil and gas wells. These materials fill the annulus between the well casing and the rock forming a protective layer, known as sealant, which is used primarily to secure and support the casing inside the well. In addition it prevents entry of unwanted fluids into the well and communication between formation fluids at different levels. These cement based sealants need to perform for many years at high temperatures and in severe chemical environments; conditions which can cause the material of the well-casing to degrade resulting in reduced strength and increased permeability. The aim of this study is to develop new materials which will have the potential properties (high strength and low permeability) for use as sealants in geothermal and deep, hot oil wells. In order to do this special cement slurries, based on the CaO−Al2O3−SiO2−H2O (CASH) hydroceramic system, have been synthesised over the temperature range 200 to 350 °C (i.e. the typical working temperature of these wells). The additives used in these cement slurries are silica flour and alumina. A detailed description of a suite of novel hydroceramic compositions over the temperature range 200 to 350 °C is given. X-ray diffraction has been used to determine the mineralogical composition and Rietveld refinement to quantify the known phases present at different temperatures. In addition the chemistry of some of the major phases present has been examined using electron probe microanalysis. Scanning electron microprobe and simulation software have been employed to study the crystal shape of these major minerals. The engineering properties of the hydroceramic materials are very important. A study of the compressive strength and permeability has been carried out over a range of temperature (200 to 350 °C). In addition permeability has been calculated using simulation software and the results compared with experimental values. Hydroceramic formulations with excellent strength and permeability measurements have been found. Some of these formulations have been tested for durability under simulated well conditions. These materials have been immersed into different brines for a certain period of time at temperatures between 200 to 300 °C. Some preliminary results regarding the changes in mineralogy in these samples are presented in this thesis. These experiments have been carried out at the Synchrotron Radiation Source (SRS) using tomographic energy-dispersive diffraction imaging (TEDII).

Closely packed myosin filaments are an example of a disordered biological array responsible for the contraction of muscle. X-ray fiber diffraction data is used to study these biomolecular assemblies but the inherent disorder in muscle makes interpretation of the diffraction data difficult. Limited knowledge of the precise nature of the myosin lattice disorder and its effects on X-ray diffraction data is currently limiting advances in studies on muscle structure and function. This thesis covers theoretical and computational efforts to incorporate the myosin lattice disorder in X-ray diffraction analysis. An automated image analysis program is developed to rapidly and accurately quantitate the disorder from electron micrographs of muscle cross-sections. The observed disorder is modelled as an antiferromagnetic Ising model and the model verified using Monte Carlo simulations. Theory and methods are developed for efficient calculation of cylindrically averaged X-ray diffraction from two-dimensional lattices that incorporate this disorder.

This thesis primarily focuses on the systematic understanding of structure – reactivity relationships in two representative systems: bixbyite and related structures as well as indium doped CeO2. Topotactic reaction routes have gained significant attention over the past two decades due to their potential to access kinetically controlled metastable materials. This has contributed substantially to the understanding of solid state reaction pathways and provided first insights into mechanisms. Contrary to the widely used ex-situ methods, in – situ techniques including powder x-ray diffraction and thermogravimetric – differential thermal analysis have been employed extensively throughout this work in order to follow the reaction pathways in real time. Detailed analysis of the AVO3 (A = In, Sc) bixbyite reactivity under oxidative conditions has been carried out and a variety of novel metastable oxygen defect phases have been identified and characterized. The novel metastable materials have oxygen deficient fluorite structures and consequently are potential ion conductors. Structural aspects of the topotactic vs. reconstructive transformations are illustrated with this model system. The structure – reactivity study of AVO3 phases was extended to AVO3 perovskite family. Based on the research methodologies and results from AVO3 bixbyite reactivity studies a generalized mechanistic oxidation pathway has been established with a non-vanadium phase, ScTiO3 bixbyite. However, there is stark contrast in terms of structural stability and features beyond this stability limit during AVO3 and ScTiO3 bixbyite reaction pathways. A series of complex reaction sequences including phase separation and phase transitions were identified during the investigation of ScTiO3 reactivity. The two-step formation pathway for the fluorite – type oxide ion conductor Ce1-xInxO2-δ (0 ≤ x ≤ 0.3) is being reported. The formation of the BaCe1-xInxO3-δ perovskites and the subsequent CO2-capture reaction with the formation of Ce1-xInxO2-δ (0 ≤ x ≤ 0.3) has been investigated in detail. The two-step formation pathway is contrasted with the unsuccessful direct method. The stability and the extent of In – doping for the CeO2 fluorite phases that can be achieved through this CO2 – capture method are reported. The necessity and strategies for the selection of appropriate intermediate precursors for the preparation of doped CeO2 are also reported.

Over the last decade progress towards step-wise structural transformations in solid state chemistry has been made using metal hydride reductants. Alkali and alkali-earth metal hydrides can effectively reduce transition metal oxides resulting frequently in novel oxygen defect structures. This provides access to control over cation oxidation states and magnetic exchange pathways, and thus electronic and magnetic properties. The goal for this research was to investigate a representative system that could be used both for exploration of novel oxygen defect phases and for investigating the fundamental parameters governing successful solid state reductions. The systems chosen for investigation were Sr2-xCaxMnO4 (0<x<2) and Sr2-xBaxMnO4 (x< 0.04). Detailed analysis of metal hydride reactivity with Sr2MnO4 is presented in addition to proof of the solid state reduction mechanism. As a result a number of novel oxygen defect phases have been produced, Sr2MnO4-x (0<x<0.37). The potential for producing novel lithium doped Sr2MnO4-x phases using a reduction/insertion approach with LiH has also been identified. Lastly as a test of application for metal hydrides as reductants the ability to topotactically reduce ScVO4 has been investigated.

The simple cubic ReO₃-type framework has all of the key features required for negative thermal expansion (NTE) arising from the transverse thermal motion of bridging atoms and rotation of rigid polyhedra. Although ReO₃ itself only displays low NTE below ambient temperature, there is a potentially large family of isostructural fluorides and oxyfluorides that could display NTE. However, the coefficients of thermal expansion (CTE) of ReO₃-type materials range from strongly positive to strongly negative. Through extensive use of in situ synchrotron diffraction, this thesis examines the thermal expansion of several ReO₃-type fluorides and oxyfluorides, demonstrating the effects on CTE and related properties of both cation and anion substitution and the disorder produced by these structural changes.

The object of this thesis is the study of nanostructured thin films using inelastic fight scattering and elastic x-ray scattering techniques. Their use in combination with other techniques is a powerful tool for the investigation of nanostructured materials. X-ray, Raman and Brillouin characterisation of cluster-assembled carbon films, promising for applications in the field of catalysis, hydrogen storage and field emission, is here presented. X-ray reflectivity (XRR) provided a measure of the density. Raman spectroscopy showed that the local bonding in these amorphous films depends on the size distribution of the clusters and that it is possible to select the cluster size in order to grow films with tailored properties. Brillouin scattering provided a characterisation at the mesoscopic scale and an estimate of the elastic constants, revealing a very soft material. XRR was employed to study density, layering and roughness of a wide range of amorphous carbon films grown with different techniques. Some films possess an internal layering due to plasma instabilities in the deposition apparatus. By comparing XRR with Electron Energy Loss Spectroscopy, a unique value for the electron "effective mass" was deduced and a general relationship between sp(^3)-content and density was found. XRR and H effusion were used to determine the hydrogen content. A study of the size-dependent melting temperature in tin nanoparticle thin films was undertaken with a combined use of X-Ray Diffraction (XRD) and light scattering. A redshift in the position of a Rayleigh peak in the temperature-dependent Brillouin measurements was shown to be related to the melting of the nanoparticles and explained by an effective medium model. XRD also provided information on the low-level of stress in the particles. Low-frequency Raman scattering was used to study the behaviour of the acoustic modes of a single particle as a function of temperature.

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