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1
Hinrichsen, Bernd. "Two-dimensional X-ray powder diffraction." [S.l. : s.n.], 2007. http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-33946.
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Hamman, David. "A holistic view on the impact of gold and uranium mining on the Wonderfonteinspruit / David Hamman." Thesis, North-West University, 2012. http://hdl.handle.net/10394/8155.
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Barnett, Stephanie Jayne. "X-ray powder diffraction studies of ettringite and related systems." Thesis, Staffordshire University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.244708.
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Tremayne, Maryjane. "Ab initio structure determination from X-ray powder diffraction data." Thesis, University of St Andrews, 1995. http://hdl.handle.net/10023/6503.
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Many important crystalline solids cannot be prepared in the form of single crystals of sufficient size and quality for single crystal X-ray diffraction studies, and in such cases it is essential that structural information can be extracted from powder diffraction data. In this thesis, a number of crystal structures have been determined directly from X-ray powder diffraction data recorded on a conventional laboratory instrument, and the limitations of this technique explored using both conventional and new more sophisticated methods of structure solution. This work has focussed mainly on the more complex problem of molecular systems. The Patterson method has been applied to the determination of a simple unknown inorganic structure, lithium perchlorate, whereas conventional direct methods have been used in the determination of a number of organic structures, including the previously unknown crystal structure of 1,3,4,6-tetrathiopentalene-2,5-dione and formylurea - the first previously unknown organic structure containing only light atoms to be solved by this technique. The combined maximum entropy and likelihood method has been applied to determinate two crystal structures, lithium triflate and p-toluenesulphonhydrazide. Further developments of this technique are also discussed and illustrated in the structure solution of a previously known system. A Monte Carlo algorithm for ab initio crystal structure determination from powder diffraction data has also been developed, and the success of this method demonstrated by its application to the determination of several known structures, and the previously unknown crystal structure of p-bromophenylacetic acid. The effect of data range on the quality of structure solution obtained from both direct methods and the maximum entropy and likelihood method is also discussed.
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McBride, Lorraine. "Determination of organic crystal structures by X ray powder diffraction." Thesis, University of Strathclyde, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248694.
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Rodriguez, Asiloe Jasmina Mora. "High resolution powder diffraction studies of molecular solids." Thesis, Keele University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321299.
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Genetu, Teggen Linda. "Material identification using X-ray diffraction." Thesis, Mittuniversitetet, Institutionen för elektronikkonstruktion, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-37122.
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This study reviews the theoretical and experimental aspects of the X-ray diffraction (XRD) technique and evaluates its use in identifying toxic elements or compounds in waste that has been incinerated. Many industries incinerate materials that contain large significant amounts of toxic elements, and these elements should be identified and re-moved to reduce environmental pollution. The aim of this project is to identify the elemental content of an incinerated ash sample, and to recommend a proper identification method when using XRD. Here, we test two ash samples (raw ash without any treatment and ash that has been stabilized by washing) using the software DIFFRAC.EVA that is integrated into Bruker’s diffractometer D2Phaser to match different diffraction patterns to identify the contents of the ash sample. Finally concluding the results XRF is more suitable than XRD for ash surveil-lance.
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Bell, A. M. T. "Structural studies using synchrotron X-ray powder diffraction and other techniques." Thesis, University of Cambridge, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.596545.
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Chapter 1 gives an introduction to X-ray and neutron powder diffraction and the use of these techniques for crystal structure determination and refinement. The Rietveld structure refinement method is described and examples of different methods of structure determination from powder diffraction data are given. The techniques of EXAFS and Mössbauer spectroscopy, which were used to provide additional structural information, are also introduced. Chapter 2 describes the different radiation sources and experimental techniques used in this work. Chapter 3 describes a structural study of magnetite, Fe3O4, below the Verwey phase transition (120 K). The P2/c structure of Fe3O4 at 60 K has been refined with lattice parameters of a = 5.9412(3) Å, b = 5.9290(3) Å, c = 16.789(1) Å and β = 90.196(4). A variable temperature study of the Fe3O4 lattice parameters between 2-280 K shows this transition is first-order. An EXAFS study between 8-270 K shows that there is no significant change in the average Fe-O distance in Fe3O4 around the transition. Chapter 4 describes a structural study on a material related to magnetite, Fe2OBO3. Two phase transitions have been found for this material. The first of these is due to magnetic ordering and takes place at 155 K. The second is due to charge ordering and takes place at 315 K, this is a structural (P21/c ↔ Pnma) transition. Chapter 5 describes a resonant scattering experiment done on CsI. Resonant scattering parameters have been refined from synchrotron X-ray powder diffraction data collected at room temperature and at 4 K close to the Cs and I K-edges. The refined f parameters are -6.2(2) e/atom (Cs, λ = 0.3453 Å), -9.0(I) e/atom (I, λ = 0.374105 Å) and -6.2(2) e/atom (I, 4 K, λ = 0.37367 Å). Chapter 6 describes the ab initio structure determination of 4-(2'3'4'-trifluorophenyl)-1235 dithiadiazolyl (C7S2N2F3H2; P2/n, a = 11.543(4) Å, b = 20.666(8) Å, c = 7.045(2) Å and β = 100.35(4) using synchrotron X-ray powder diffraction data. A global optimisation method was used to provide a starting model for Rietveld refinement.
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Day, Sarah Joanne. "Studies of cosmic dust analogues using synchrotron X-ray powder diffraction." Thesis, Keele University, 2014. http://eprints.keele.ac.uk/1215/.
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The structural evolution of cosmic dust analogues has been investigated using in situ synchrotron X-ray powder diffraction (SXPD) at the Diamond Light Source. Amorphous Mg/Ca silicates are produced as analogues of cosmic dust using a modified sol-gel method. They are studied under non-ambient temperature and pressure conditions using in situ powder diffraction, complemented by FTIR and Raman spectroscopy. The solid-state mineralisation of amorphous grains is observed by thermal annealing and the results of this allow the environmental conditions leading to the formation of crystalline dust grains in astrophysical environments to be constrained. The solid-gas carbonation of amorphous Ca-rich silicates is studied using in situ SXPD and analysed using full-profile fitting techniques, while the effect of ex situ carbonation on the short range ordering of amorphous grains is investigated using high energy SXPD and Pair Distribution Function (PDF) analysis. The formation of a metastable calcium carbonate phase (vaterite) is observed and the importance of this in relation to astrophysical environments is discussed. In situ Raman and SXPD data of CO2 clathrate hydrates are presented and the importance of the Raman data obtained here with relevance to future remote sensing missions to Solar System bodies is discussed. This work indicates the importance of laboratory work to the field of astrophysics and provides novel experimental approaches to aid our understanding of astrophysical processes.
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Seaton, Colin Cormack. "Novel methods of structure determination from X-ray powder diffraction data." Thesis, University of Birmingham, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396462.
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The determination of crystal structures from powder diffraction data is a field that is rapidly expanding due to a range of computational and experimental developments. A major driving force of this expansion is the continuing development of direct space methods of structure solution. This work will show the development of the program POSSUM as a suite of direct space structure determination methods and its subsequent successful application to a number of molecular organic and inorganic materials whose crystal structures were previously unknown. Direct space methods utilise global optimisation algorithms to locate the crystal structure. This work describes the successful application of the differential evolution optimisation algorithm to structure determination from powder diffraction. Differential evolution is shown to be a robust and efficient optimisation technique with the limited number of control parameters associated with the method ensuring that optimisation of the searching is easily achieved. Investigation into improving the computer performance of the method also focused on reduction of the time taken to evaluate agreement between experimental and calculated patterns through the application of the discrete wavelet transform. This effectively reduces the number of points in the powder pattern, yet retains the same level of information as the original data set and is shown to illustrate good discrimination between solutions generated in a direct space structure solution.
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Bright, Andrew G. "Mechanistic Insights into the Stabilisation of Biopharmaceuticals using Glycine Derivatives. The Effect of Glycine Derivatives on the Crystallisation, Physical Properties and Behaviour of Commonly used Excipients to Stabilise Antigens, Adjuvants and Proteins in the Solid State." Thesis, University of Bradford, 2015. http://hdl.handle.net/10454/15943.
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This dissertation has focused on studying the effect of four glycine derivatives on the solid state properties of mannitol, glycine, and sucrose when freeze dried into blended mixtures. The primary goal was to assess their value for use in the stabilisation of vaccines in the solid state, by examining key physical and chemical characteristics, which have been documented to be beneficial to the stabilisation of biopharmaceutical formulations. The novel excipients; dimethyl glycine, and trimethyl glycine, were shown to retard the crystallisation and increase the overall glass transition temperature, of mannitol, when freeze dried as evidenced by DSC and Powder X-ray diffraction. Mannitol’s glass transition temperature increased from 100C to 12.650C and 13.610C when mixed with methyl-glycine and dimethyl glycine respectively. The glycine derivatives did not show the same effect on sucrose which remained amorphous regardless of the concentration of the other excipient. The different behaviour with the sucrose system was thought to be due to relatively high glass transition temperature of sucrose. Conversely glycine remained highly crystalline due it’s relatively low glass transition temperature. The novel excipient formulations were also assessed for their effect on the aggregation of the adjuvant aluminium hydroxide when freeze dried by Dynamic Light Scattering (DLS).The formulations containing the glycine derivatives all caused a decrease in the aggregation size of the adjuvant from ~26 μm, to 185 nm in the presence of methyl glycine. The effects of lysozyme and viral antigen on the adjuvants were also examined showing that the addition of the virus did not affect the size of the aggregates formed, however lysozyme showed significant decreases in the aggregates formed. Examination of the freezing method were also made showing that faster freezing rates produced smaller aggregates of the adjuvant. When investigating the rate at which the excipients lost water during secondary drying there was evidence of the formation of hydrates of glycine, trimethyl glycine, and mannitol has shown that the glycine derivatives have attributes which would be beneficial in stabilising vaccines in the solid state when freeze dried.
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Sitepu, Husinsyah. "Characterisation of preferred orientation in crystalline materials by x-ray powder diffraction." Curtin University of Technology, School of Physical Sciences, 1991. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=10554.
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Texture, i.e. preferred orientation, can cause large systematic errors in quantitative analysis of crystalline materials using x-ray powder diffraction (XRPD) data. Various mathematical forms have been proposed for the application of preferred orientation corrections. The most promising of these appears to be the single-parameter March (1932) model proposed by Dollase (1986).Li and O'Connor (1989) applied the March model to determine the level of preferred orientation in various gibbsites using two procedures. The first involved the Rietveld (1969) least squares pattern-fitting method. Each pattern was Rietveld-analysed in two ways, initially assuming random orientation of the crystallites and subsequently with the March model. The second procedure for preferred orientation analysis, described here as the line ratio method, determines preferred orientation factors according to the intensity ratios of carefully selected line pairs.In the thesis the procedures proposed by Li and O'Connor for texture analysis have been evaluated with XRPD data sets for molybdite, calcite and kaolinite. The results indicate that while the March formula improves agreement between the' calculated and measured patterns in Rietveld analysis, other forms of systematic error in the intensity data appear to limit the effectiveness of the March formula in general. It has been found also that the line ratio method improves agreement between the data sets, but less effectively than the Rietveld method. It is proposed that extinction is likely to be the most influential source of systematic error competing with texture.
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Wilkinson, Angus P. "Some applications of synchrotron X-ray powder diffraction to solid-state chemistry." Thesis, University of Oxford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302908.
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Wang, Te-Kang. "A powder X-ray diffraction study of two aluminum-lithium based alloys." Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/43736.
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Approved for public release; distribution is unlimited.The microstructures of solution treated, quenched and aged A1-2.5 wt. %Li and A1-2.0 wt.%Li-2.76 wt.%Mg-1.03 wt.%Cu alloys were studied by powder X- ray diffraction. The as-quenched alloys showed extensive X-ray line broadening due to particle size effects and the intensity measurements indicated a significant amount ordering in the as-quenched state. These results were interpreted using a 'spinodal ordering' model which suggests that A1-Li-based alloys order during quenching and then spinodally decompose into regions of order and disorder so that the final microstructure comprises small ordered regions (size 40 nm) in a disordered matrix Studies on the aged A1-2.5 wt.%Li alloy indicated that after initial short-time aging, particle growth follows Ostwald ripening kinetics in agreement with previous work. Studies on the aged quaternary alloy indicated that T1 and S phases grow in this system so that precipitates are not a dominant strengthening mechanism in this alloy.
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Chan, Fung Choy. "Powder X-ray diffraction studies of structural and kinetic aspects of polymorphism." Thesis, King's College London (University of London), 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327050.
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Ren, Zhe. "Nanomechanics : combining mechanical testing in situ with focused X-ray diffraction on a synchroton beamline." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4387.
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Les nanostructures ont des propriétés mécaniques qui diffèrent de celles des matériaux massifs. La compréhension des propriétés mécaniques aux échelles nanométriques requièrent la mise en place d’essais mécaniques combinés à des observations structurales. Au cours de cette thèse nous avons développé un microscope à force atomique (AFM) dédié permettant de solliciter mécaniquement un nano-objet unique sur une ligne de lumière synchrotron. Les possibilités offertes par cette nouvelle approche expérimentale sont démontrées sur deux exemples de sollicitation mécanique in situ: (i) la nanoindentation in situ de cristaux d’or combinée à la diffraction cohérente des rayons X; (ii) la flexion trois points de nanofils d’or associée à la micro-diffraction de Laue. Ces expériences permettent d'accéder au comportement élastique ainsi qu’au comportement plastique du nanomatériau et permettent de déterminer la limite d'élasticité et le type de défauts induits par le chargement mécaniqueNanostructures were found to exhibit different mechanical properties compared to their bulk counterpart. For obtaining further insight into the mechanical behaviour on the nanoscale, mechanical tests are combined with observation techniques allowing for monitoring the structural evolution. Within this thesis a special atomic force microscope has been developed which is compatible with different X-ray diffraction techniques at synchrotron sources for in situ mechanical testing on single nano-objects. The great potential of the new experimental approach is demonstrated on two kinds of in situ mechanical tests: (i) in situ nano-indentation on Au crystals with coherent X-ray diffraction. (ii) In situ three point bending tests on Au nanowires with μLaue diffraction. These experiments give access to the elastic as well as the plastic behavior of the nanomaterial and allows for determining the elastic limit and the type of defects induced by the mechanical loading
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Aziz, Fauziah Haji. "Indexing and structural studies of materials by high-resolution X-ray powder diffraction." Thesis, University of Surrey, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.232903.
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Docherty, Andrea. "Crystal structure solution and refinement of pharmaceutical molecules using x-ray powder diffraction." Thesis, University of Strathclyde, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399726.
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Griffith, Kent Joseph. "Atomic and electronic structure of complex metal oxides during electrochemical reaction with lithium." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/271191.
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Lithium-ion batteries have transformed energy storage and technological applications. They stand poised to convert transportation from combustion to electric engines. The discharge/charge rate is a key parameter that determines battery power output and recharge time; typically, operation is on the timescale of hours but reducing this would improve existing applications and open up new possibilities. Conventionally, the rate at which a battery can operate has been improved by synthetic strategies to decrease the solid-state diffusion length of lithium ions by decreasing particle sizes down to the nanoscale. In this work, a different approach is taken toward next-generation high-power and fast charging lithium-ion battery electrode materials. The phenomenon of high-rate charge storage without nanostructuring is discovered in niobium oxide and the mechanism is explained in the context of the structure–property relationships of Nb2O5. Three polymorphs, T-Nb2O5, B-Nb2O5, and H-Nb2O5, take bronze-like, rutile-like, and crystallographic shear structures, respectively. The bronze and crystallographic shear compounds, with unique electrochemical properties, can be described as ordered, anion-deficient nonstoichiometric defect structures derived from ReO3. The lessons learned in niobia serve as a platform to identify other compounds with related structural motifs that apparently facilitate high-rate lithium insertion and extraction. This leads to the synthesis, characterisation, and electrochemical evaluation of the even more complicated composition–structure–property relationships in ternary TiO2–Nb2O5 and Nb2O5–WO3 phases. Advanced structural characterisation including multinuclear solid-state nuclear magnetic resonance spectroscopy, density functional theory, X-ray absorption spectroscopy, operando high-rate X-ray diffraction, and neutron diffraction is conducted throughout to understand the evolution of local and long-range atomic structure and changes in electronic states.
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Atkins, Alison J. "Solid state studies of ternary oxides and sulphides." Thesis, University of Nottingham, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320791.
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McDowell, John Christopher. "Preparation characterisation and stability of selected high critical temperature ceramic superconductors." Thesis, University of Ulster, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260854.
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Smith, Thomas. "Studies of p-type semiconductor photoelectrodes for tandem solar cells." Thesis, Loughborough University, 2014. https://dspace.lboro.ac.uk/2134/14522.
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Photoelectrodes and photovoltaic devices have been prepared via multiple thin film deposition methods. Aerosol assisted chemical vapour deposition (AACVD), electrodeposition (ED), chemical bath deposition (CBD) and doctor blade technique (DB) have been used to deposit binary and ternary metal oxide films on FTO glass substrates. The prepared thin films were characterised by a combination of SEM (Scanning Electron Microscopy), powder X-ray diffraction, mechanical strength tests and photochemical measurements. Nickel oxide (NiO) thin films prepared by AACVD were determined to have good mechanical strength . with a photocurrent of 7.6 μA cm-2 at 0 V and an onset potential of about 0.10 V. This contrasted with the dark current density of 0.3 μA cm-2 at 0 V. These NiO samples have very high porosity with crystalline columns evidenced by SEM. In comparison with the AACVD methodology, NiO films prepared using a combination of ED and DB show good mechanical strength but a higher photocurrent of 24 μA cm-2 at 0 V and an onset potential of about 0.10 V with a significantly greater dark current density of 7 μA cm-2 at 0 V. The characteristic features shown in the SEM are smaller pores compared to the AACVD method. Copper (II) oxide (CuO) and copper (I) oxide (Cu2O) films were fabricated by AACVD by varying the annealing temperature between 100-325°C in air using a fixed annealing time of 30 min. It was shown by photocurrent density (J-V) measurements that CuO produced at 325 °C was most stable and provided the highest photocurrent of 173 μA cm-2 at 0 V with an onset potential of about 0.23 V. The alignment of zinc oxide (ZnO) nano-rods and nano-tubes fabricated by CBD have been shown to be strongly affected by the seed layer on the FTO substrate. SEM images showed that AACVD provided the best seed layer for aligning the growth of the nano-rods perpendicular to the surface. Nano-rods were successfully altered into nano-tubes using a potassium chloride bath etching method. NiO prepared by both AACVD and the combined ED/DB method were sensitized to absorb more of the solar spectrum using AACVD to deposit CuO over the NiO. A large increase in the photocurrent was observed for the p-type photoelectrode. These p-type photoelectrode showed a photocurrent density of approximately 100 μA cm-2 at 0 V and an onset potential of 0.3 V. This photocathode was then used as a base to produce a solid state p-type solar cell. For the construction of the solid state solar cells several n-type semiconductors were used, these were ZnO, WO3 and BiVO4. WO3 and BiVO4 were successfully produced with BiVO4 proving to be the optimum choice. This cell was then studied more in depth and optimised by controlling the thickness of each layer and annealing temperatures. The best solid state solar cell produced had a Jsc of 0.541 μA cm-2 (541 nA) and a Voc of 0.14 V, TX146 made up of NiO 20 min, CuFe2O4 50 min, CuO 10 min, BiVO4 27 min, using AACVD and then annealed for 30 min at 600°C.
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Edwards, Clare M. "Application of high-pressure spectroscopic and powder X-ray diffraction techniques to inorganic materials." Thesis, McGill University, 1998. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=37544.
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The vibrational spectra (IR, Raman) of (eta6-C 6H5CO2CH3)Cr(CO)3, (eta 6-C6H5CO2CH3)Cr(CO) 2(CS), [Pt(NH3)4][PtCl4] (MGS), [Pt(ND 3)4] [PtCl4] (MGS-D), [Pt(NH 3)4][PtBr4] (MGS-Br), ReH7(dppe) (dppe = 1,2-bis(diphenylphosphino)ethane) and CpCo(C64H4) (Cp = cyclopentadiene) have been studied under pressures up to ∼45 kbar. The magnitude and direction of the pressure-induced shift of the Raman-active nu(CO) and nu(CS) vibrational modes of (eta6-C6H 5CO2CH3)Cr(CO)3 and (eta6 -C6H5CO2CH3)Cr(CO) 2(CS) indicate an increase in the amount of pi-backbonding to the CO and CS ligands, under pressure, the increase being greater to the CO ligand than to the CS ligand. Wavenumber vs. pressure plots revealed a phase transition in both the tricarbonyl and thiocarbonyl complexes between 10--15 kbar. For CpCo(C64H4), discontinuities in the wavenumber vs. pressure plots at 10 kbar indicate a phase transition at this pressure, most likely involving rotation of the Cp ring. Insertion of the Co atom into the cage does not occur under compression; a shift to higher wavenumbers was observed for all the Raman and IR vibrational modes of CpCo(C64H4) and the parent fulleride, C 64H4. Phenyl ring rotation is thought to occur in ReH 7(dppe) under compression. Three pressure regions, from ambient pressure to ∼16 kbar, between 16 and 29 kbar and above 29 kbar, were identified from the wavenumber vs. pressure plots. A broad, weak feature in the ER spectrum appears from 5 kbar, increasing in intensity with increasing pressure. This peak has been assigned to the nu(HH) mode of a coordinated dihydrogen ligand, Re(eta2-H2). Ring rotation may assist the pressure-induced dihydride-dihydrogen interconversion. The pressure-tuning IR study of MGS and its derivatives probed the intermolecular interactions, in particular the interactions of the NH3 groups and investigated the hypothesis that hydrogen bonding of the type N- H&cdots;Cl exists in MGS. Splitting of the IR bands at ambient pressure, and
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Edwards, Clare M. "Applications of high-pressure spectroscopic and powder x-ray diffraction techniques to inorganic materials." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0005/NQ44419.pdf.
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Taylor, Ryan. "Structural insights into pharmaceutical solids from synchrotron and laboratory x-ray powder diffraction data." Thesis, University of Strathclyde, 2012. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=25783.
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Structural insights into a wide range of pharmaceutically relevant solids, including pharmaceutical salts, co-crystals and amorphous solids have been gained through the use of X-ray powder diffraction techniques. By combining global optimisation methods with high-quality powder diffraction data collected in the laboratory or at a synchrotron radiation source, the crystal structures of pharmaceutically relevant materials were solved successfully and reproducibly. The crystal structures which were solved are moderately complex, and at the midpoint of the complexity that can be routinely tackled by the DASH structure solution package. The crystal structures of six salts of the β2-adrenoceptor agonist, salbutamol were solved directly from powder diffraction data collected in the laboratory. For five of these salts, no single crystals could be grown, however, for one salt, a single crystal was obtained, and comparison of the single crystal structure with the structure solved from powder diffraction data confirms the excellent accuracy of structures from powder diffraction data. Co-crystals of the anti-epileptic drug, carbamazepine were examined on beamline I11 at Diamond Light Source in Oxfordshire. The beamline was in the optimisation phase when the co-crystals were examined, and were the first fully organic structures to be examined on the beamline. The accuracy of the structures solved from powder data was confirmed by comparison with published single crystal structures. Additional carbamazepine co-crystal structures were solved from laboratory powder diffraction data in order to assess the increase in accuracy associated with high resolution powder diffraction collected at a synchrotron radiation source. Total scattering pair distribution function (TS-PDF) analysis was carried out on nanocrystalline powders of carbamazepine and the NSAID indomethacin, and it was found that melt-quenched “amorphous” carbamazepine is in actual fact a nanocrystalline version of form II, which is the clinically used polymorph.
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Intisar, Amir. "A portable CCD array detector for in-situ analysis of powder samples using combined X-ray diffraction/X-ray fluorescence techniques." Thesis, Brunel University, 2010. http://bura.brunel.ac.uk/handle/2438/4401.
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This work describes the design, development and testing of a portable charge-coupled device detector system to be used for the simultaneous collection of X-ray diffraction and X-ray fluorescence data from powdered samples. The detector was designed for both terrestrial and extra-terrestrial applications that require in-situ analysis of samples, where access to a laboratory instrument is restricted. The detector system incorporates 4 e2v technologies CCD30-11 devices, employing multi-phase pinned technology for low noise operation. Geometrical calculations and thermal studies concerning the design of the detector are presented, with particular emphasis on motivations for the chosen geometry. Initial characterisation and calibration of the detector was performed in a laboratory environment using a purpose built test facility. The test facility included a high brightness X-ray micro-source from Bede Scientific Instruments, coupled with an XOS polycapillary collimating optic, which was used to deliver a focused beam of low divergent X-rays to the sample. The design of the test facility is discussed and the spectra and flux produced by the X-ray micro-source are investigated. The operational performance of the detector is highlighted and the use of the instrument in different applications is described, namely the planetary sciences and pharmaceuticals sector. Finally, based on the knowledge gained from initial testing of the instrument, improvements to the detector design are outlined, which greatly enhance the combined X-ray diffraction/X-ray fluorescence performance of the instrument.
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Guo, Peng. "Structure Determination and Prediction of Zeolites : A Combined Study by Electron Diffraction, Powder X-Ray Diffraction and Database Mining." Doctoral thesis, Stockholms universitet, Institutionen för material- och miljökemi (MMK), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-127750.
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Zeolites are crystalline microporous aluminosilicates with well-defined cavities or channels of molecular dimensions. They are widely used for applications such as gas adsorption, gas storage, ion exchange and catalysis. The size of the pore opening allows zeolites to be categorized into small, medium, large and extra-large pore zeolites. A typical zeolite is the small pore silicoaluminophosphate SAPO-34, which is an important catalyst in the MTO (methanol-to-olefin) process. The properties of zeolite catalysts are determined mainly by their structures, and it is therefore important to know the structures of these materials in order to understand their properties and explore new applications. Single crystal X-ray diffraction has been the main technique used to determine the structures of unknown crystalline materials such as zeolites. This technique, however, can be used only if crystals larger than several micrometres are available. Powder X-ray diffraction (PXRD) is an alternative technique to determine the structures if only small crystals are available. However, peak overlap, poor crystallinity and the presence of impurities hinder the solution of structures from PXRD data. Electron crystallography can overcome these problems. We have developed a new method, which we have called “rotation electron diffraction” (RED), for the automated collection and processing of three-dimensional electron diffraction data. This thesis describes how the RED method has been applied to determine the structures of several zeolites and zeolite-related materials. These include two interlayer expanded silicates (COE-3 and COE-4), a new layered zeolitic fluoroaluminophosphate (EMM-9), a new borosilicate (EMM-26), and an aluminosilicate (ZSM-25). We have developed a new approach based on strong reflections, and used it to determine the structure of ZSM-25, and to predict the structures of a series of complex zeolites in the RHO family. We propose a new structural principle that describes a series of structurally related zeolites known as “embedded isoreticular zeolite structures”, which have expanding unit cells. The thesis also summarizes several common structural features of zeolites in the Database of Zeolite Structures.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 3: Manuscript.
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Strusevich, Dmitry. "Development of in-situ synchrotron X-ray powder diffraction techniques for studies of catalytic systems." Thesis, Birkbeck (University of London), 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.497909.
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Smith, Elaine D. L. "Combined molecular modelling and powder X-ray diffraction for crystal structure solution of organic materials." Thesis, Heriot-Watt University, 2004. http://hdl.handle.net/10399/249.
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Fowkes, Amelia Jane. "High resolution powder neutron diffraction in solid state inorganic chemistry." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299525.
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Soleilhavoup, Anne. "Structural studies on functional materials using solid-state NMR, powder X-ray diffraction and DFT calculations." Thesis, Durham University, 2009. http://etheses.dur.ac.uk/8/.
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Analytical and theoretical techniques were used in this work for structural studies of framework materials. One and two dimensional 31P and 17O solid state NMR experiments highlight subtle thermally induced structural changes in (MoO2)2P2O7 pyrophosphate, tungsten trioxide WO3 and negative thermal expansion ZrW2O8. DFT methods using CASTEP software to calculate 31P and 17O NMR parameters are performed on these structures and discussed in comparison to experimental results, published structures and thermal mechanisms.
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Stoner, Troy A. "Preparation of Extinction Free Gamma Ti-51at.%Al Alloy Powder and Characterization by X-ray Diffraction." Thesis, Monterey, California. Naval Postgraduate School, 1992. http://hdl.handle.net/10945/27221.
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The lattice parameters, structure factors, and Debye-Waller temperature factor of a homogenized, binary Ti-51at.%Al intermetallic alloy were determined using powder X-ray diffraction (XRD). Previous studies have been hampered by extinction at low Bragg angles, therefore improved powdering methods were implemented. The powder was produced by pulverizing lathe turnings taken from the sample ingot using a ceramic mortar and pestle. then the powder was passed through a U.S. Standard 400 sieve mesh (38 microns). After further grinding a new acoustical sieving procedure was performed where powder particles were passed through a 2000 line per inch sieve mesh (5-7 microns). Next the powder was annealed to relieve induced stress produced during grinding. An X-ray diffraction study was conducted for Bragg angles 10-140 deg. The L1 structured TiAl lattice parameters of a =4.002 and c=4.081 were determined using XRD peak positions. the resulting c/a ratio equalled 1.02. The measured integrated intensities of the fundamental reflections were used to determine a Debye-Waller temperature factor of B=0.65 using the Wilson method. these values were determined to be accurate based on comparison to previous research and theoretical approximations. The effects of extinction at low angles were not completely avoided with the refined powder particle size however, they were significantly reduced
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Hou, Weimin. "A novel method for the determination of single crystal elastic constants using powder X-ray diffraction." Thesis, University of Ottawa (Canada), 2002. http://hdl.handle.net/10393/6338.
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The elastic properties of a material have long been a subject of interest in materials science and physics. Especially, a complete determination of the single crystal compliance and stiffness tensor is of great importance, as the single crystal elastic tensor provides a complete description of the elastic properties of a material. There are numerous materials that are only available in polycrystalline form. Many of these polycrystalline materials are of great interest, such as the polycrystalline materials synthesized under high pressure conditions, for which the elastic properties under high pressure conditions are particularly important. However, traditional methods to measure the elastic constants apply only to single crystals. Recently, Singh and co-workers have developed a method, using energy dispersive X-ray diffraction to measure the single crystal elastic constants of a material at elevated pressures, which, for the first time, enabled the single crystal elastic tensors of numerous polycrystalline samples to be determined. Inspired by the energy dispersive X-ray diffraction method, we have undertaken to develop a novel method, using angle dispersive X-ray diffraction techniques combined with a two-dimensional X-ray recording area detector, to measure the single crystal elastic constants of powder samples. We have obtained important results that will enable the single crystal elastic constants of concerned material to be determined from Debye rings recorded on the X-ray recording image plate. In comparison to the energy dispersive X-ray diffraction method, the angle dispersive X-ray diffraction method offers advantages, as we will demonstrate.
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Hernandez, Antonio. "Ultrafast Soft Mode Dynamics in Ferroelectrics studied with Femtosecond X-Ray Diffraction." Doctoral thesis, Humboldt-Universität zu Berlin, 2020. http://dx.doi.org/10.18452/21041.
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Ferroelektrische Materialien sind ein Schlüsselbereich der aktuellen Forschung und weisen zahlreiche wichtige technologische Anwendungen auf. Diese Klasse kristalliner Feststoffe zeichnet sich üblicherweise durch eine Vielzahl von para- und ferroelektrischen Phasen auf. Letztere sind dadurch charakterisiert, dass sie auch in Abwesenheit eines äußeren Feldes eine spontane elektrische Polarisation aufweisen. Diese Eigenschaft hat ihren Ursprung in der besonderen elektronischen Struktur ferroelektrischer Materialien, die sich aus einer großen Vielfalt von Gittergeometrien und mikroskopischen Ladungsdichteverteilungen ergibt. Auf atomarer Ebene sind die komplexen Eigenschaften der Ferroelektrika bis jetzt jedoch nur teilweise verstanden. Insbesondere die Verbindung zwischen mikroskopischen elektronischen Ladungsverteilungen und der daraus resultierenden makroskopischen elektrischen Polarisation wirft eine entscheidende, momentan noch offene Frage auf. Die Ladungsdynamik und ihr Zusammenspiel mit Gitteranregungen, insbesondere Softmoden, sind auf atomaren Längen- und Zeitskalen ungelöst. In dieser Arbeit wird das Potenzial der Femtosekunden-Röntgenpulverbeugung aufgezeigt, diese Frage zu adressieren. Diese Methode ermöglicht im Rahmen dieser Arbeit die Bestimmung transienter elektronischer Ladungsdichtekarten für das prototypische ferroelektrische Ammoniumsulfat direkt unterhalb seiner Curie-Temperatur nach einer optischen Anregung. Die Analyse der experimentellen Daten deckte eine bislang unbekannte niederfrequente Gitteroszillation mit einer Periode von 3 ps und nukleare Verschiebungen im Sub-Picometer-Bereich auf, die Ladungsverschiebungen auf einer 100-pm-Längenskala induzieren. Dies sind klare Merkmale, die auf die Anregung einer Softmode hinweisen. Schließlich wird zum ersten Mal die Dynamik der makroskopischen Polarisationsänderung abgeleitet, die eine oszillatorische Umkehr der Polarität aufweist und für ultraschnelle Schaltanwendungen geeignet ist.Ferroelectrics are an area of current research, with important technological applications such as ferroelectric random access memories, infrared cameras or medical ultrasound equipment. This class of crystalline solids do not commonly only exhibit a ferroelectric phase, but rather go through an abundant variety of para- and ferroelectric phases that depend on the temperature. The ferroelectric phases present a spontaneous electric polarization even in the absence of an external field, in contrast to paraelectric phases and also exhibit a hysteresis loop in analogy to ferromagnets. This macroscopic feature has its origin in their peculiar electronic structure, which results from a rich diversity of lattice geometries and complex microscopic charge distributions. At the atomic level, however, the intricate characteristics of ferroelectrics are only partially understood. The link between microscopic charge distributions and macroscopic electric polarization poses a crucial question to be solved. The interplay of charge dynamics and lattice excitations are still unresolved on atomic length and time scales. In this thesis, femtosecond X-Ray powder diffraction is used to find solutions for these unanswered questions. This method allows for the experimental determination of time-resolved charge density maps from where the structural, charge and polarization dynamics are can be derived. These maps are determined for the photoexcited ferroelectric ammonium sulphate just below its Curie temperature. Data analysis has revealed a newly discovered low frequency lattice oscillation with a 3ps period and sub-picometer nuclear displacements that is related to periodic charge relocations on a 100pm length scale, which is a feature indicative of soft mode behavior. Finally, the dynamics of the variation of polarization are derived for the first time, showing an oscillatory reversal of polarity that holds potential for ultrafast switching applications.
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Saffarini, Ghassan. "X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and density study of ternary chalcogenide glasses based on Ge-Se and Ge-S." Thesis, Brunel University, 1991. http://bura.brunel.ac.uk/handle/2438/7396.
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Glasses of the systems Ge-Se-X (X = Ga, Sn, Bi, Sb), Ge-S-Y (Y = Ag, Ga, Sn, Bi) and Se-S have been examined using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), density and differential scanning calorimetry (DSC). Two of the compositions, GeSe2 and (GeSe2)92Ga8, have also been examined by extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES). The emphasis of the XPS measurements was on the changes in the binding energies with composition of the core peaks of the glasses, and on the plasmon energy losses from the L3M4,5M4,5 Auger lines of Se and Ge. It was found that there were small shifts in the binding energies of the core peaks on substitution but the plasmon energy changed markedly with composition. For the XRD measurements, the focus was on two features : (a) to ensure that the samples prepared were truely amorphous and (b) to confirm the presence of the first sharp diffraction peak (FSDP) on the interference functions. The density measurements showed that the addition of the third element (X or Y) to the binary resulted in an increase in the relative density except for one system, Ge-Se-Sn, which showed the opposite behaviour. The DSC measurements showed that the addition of the third element to the binary resulted in a decrease in the glass transition temperatures. The EXAFS and XANES measurements of GeSe2 and (GeSe2)92Ga8 glasses showed that there was very little change in the local order around the Ge atom in GeSe2 glass with increase in temperature and that the local order around the Ge atom changes on alloying GeSe2 with Ga. Correlations between parameters and measured properties of the ternary alloys have been investigated. It has been found that the parameter
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Jin, Xin. "Combining RBS/Channeling, X-ray diffraction and atomic-scale modelling to study irradiation-induced defects and microstructural changes." Thesis, Limoges, 2021. http://www.theses.fr/2021LIMO0017.
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Les particules énergétiques sont souvent impliquées dans les activités de la société moderne. Ils ont contribué à l'essor de l'industrie des semi-conducteurs et pourront à l'avenir jouer un rôle important dans la mise en forme des matériaux de manière contrôlée. Cependant, leur nature énergétique pose de grands défis. Ainsi, il est essentiel d'avoir une compréhension globale des mécanismes sous-jacents des défauts induits par l'irradiation et des changements microstructuraux associés. Expérimentalement, les effets induits par l'irradiation peuvent être suivis par des techniques de caractérisation telles que la rétrodiffusion de Rutherford en mode canalisé (RBS/C) et la diffraction des rayons X (XRD), pour ne citer que ces deux car elles sont extrêmement sensibles aux perturbations au sein des cristaux. Cependant, il n'est pas aisé d'établir un lien clair entre le résultat de la mesure et la quantité et la nature des défauts, et ce lien est généralement fait à partir de modèles phénoménologiques. Dans ce travail de thèse, afin de faire face à ce problème, nous avons couplé modélisations à l'échelle atomique et simulations de signaux de RBS/C et XRD. La première étape a consisté à améliorer un code de simulation RBS/C récemment développé qui peut générer des signaux à partir de structures atomiques. En modifiant les algorithmes décrivant les interactions ion-solide et en ajoutant de nouvelles fonctionnalités, nous avons amélioré la flexibilité du code et son applicabilité à différents types de matériaux. Par la suite, nous avons utilisé le code RBS/C amélioré avec un code pour la DRX, lui aussi utilisant les données de structures atomiques. Avec ces signaux, nous avons extraits des paramètres de désordre et de déformation élastique et nous avons déterminé les cinétiques d'évolution associées et ce, pour un matériau modèle, à savoir UO2. Les défauts d'irradiation ont été générés par dynamique moléculaire (MD) avec la technique de l'accumulation de paires de Frenkel. Les cinétiques issues des modélisations présentent un accord qualitativement étroit avec celles déterminées expérimentalement, indiquant la validité de la méthodologie utilisée. La décomposition des cinétiques modélisées a permis de décrire de façon quantitative l'évolution des différents de types de défauts. Enfin, nous avons calculé les signaux RBS/C et XRD à partir de cellules modèles de Fe produites par MD et contenant chacune un type de défauts à une concentration donnée, les deux informations étant connues. Une comparaison claire du désordre et de la déformation élastique induits par les différents types de défauts dans Fe a été faite. La relation entre le rendement RBS/C et l'énergie des ions sonde a également été étudiée et la dépendance en énergie, fonction de la nature des défauts, a été établie. L'approche globale utilisée dans ce travail doit désormais être étendue et testée dans d'autres matériauxEnergetic particles are involved in many activities of modern society. They constitute a significant aspect of the semiconductor industry and may play important role in shaping materials in a controllable way in the future. However, their energetic nature also poses grand challenges, especially in the nuclear industry. Thus, it is crucial to have a comprehensive understanding of the underlying mechanisms of irradiation-induced defects and the associated microstructural changes. Experimentally, irradiation-induced effects can be monitored by characterization techniques including, but not limited to, Rutherford backscattering spectrometry in channeling mode (RBS/C) and X-ray diffraction (XRD), because they are extremely sensitive to changes in the crystalline structure. However, it is not straightforward to establish a clear link between the characterization results and the defect quantity and nature, and this connection is usually made according to simple phenomenological models. In this thesis work, in order to cope with this problem, we performed RBS/C and XRD atomic-scale modelling. The first step was to improve a recently developed RBS/C simulation code that can generate RBS/C signals from arbitrary atomic structures. By modifying the algorithms describing ion-solid interactions and adding new features, we enhanced the flexibility of the code and its applicability to different types of materials. Subsequently, we employed the improved RBS/C code with a XRD program to compute disordering and elastic strain kinetics of a model material, namely UO2, as a function of irradiation fluence. Radiation defects in UO2 were simulated by molecular dynamics (MD) calculations. Both the strain and disordering kinetics exhibit qualitatively close agreement with those determined experimentally, indicating the validity of the used methodology. The decomposition of the kinetics was performed in order to study the effect of each defect separately, which enables a quantitative description of the disordering and strain build-up processes. Finally, we computed RBS/C and XRD signals from Fe MD cells, each of which contains one single type of defects. A clear comparison of disorder and elastic strain induced by different types of defects in Fe was made. The relation between RBS/C yield and He energy was also studied using the Fe MD cells, which shows dependency with defect types. The global approach used in this work has the hope to be extended and tested in more materials
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Vella-Zarb, Liana. "The complementary use of theoretical structure prediction and X-ray powder diffraction data in crystal structure determination." Thesis, University of Birmingham, 2009. http://etheses.bham.ac.uk//id/eprint/504/.
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The successful prediction of the crystal structure and symmetry of a material can give valuable insight into many of its properties, as well as the feasibility of thermodynamically stable poly-morphs to exist. It is not uncommon, however, for numerous theoretical structures to be found within a narrow energy range, making absolute characterisation of the crystal structure impossi-ble. The aim of this project was to investigate a number of structures from this scenario, high-lighting the key differences between three potential methods for the automated comparison of predicted and experimental crystal structures. This work was carried out by comparing the simulated powder diffraction patterns of theoretical predicted crystal structures of small organic materials with their experimental powder diffraction patterns, so that the experimentally identified structure could be automatically singled out from the many calculated. The use of traditional agreement factors (eg. Rwp) was compared with more sophisticated approaches namely PolySNAP, which uses principal-component analysis, and Compare.x, an algorithm based on weighted cross-correlation. Five structures were analysed, two of which had not been previously characterised. As the structure prediction calculations are carried out at 0K, and experimental data were collected over a range of temperatures (10K-293K), the effect of the resulting variations in lattice parameters on the automated processes is discussed. In all cases, Rwp has proven to be a poor and unreliable discriminator in the comparison of pre-dicted and experimental structures. The more contemporary methods based on PolySNAP and Compare.x both gave encouraging results when used to study the three known structures imida-zole, chlorothalonil and 5-azauracil, and they have consequently been used in the successful so-lution of the two previously unknown structures adenine and guanine. A difference in sensitivity in the matching of data collected at different temperatures between the latter approaches was noted. It was found that although there is considerable overlap between the two methods, they are not absolutely interchangeable, and this distinction may be exploited in future work where more case-specific comparisons are carried out. Automated comparison techniques cannot yet replace visual comparison completely, but they reduce it drastically. Ultimately, comparisons made computationally serve as a complement to human judgement, but they may not yet elimi-nate it.
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Tsuboi, Chiaki. "X-ray crystal structure analyses of magnetically oriented microcrystalline suspensions." Kyoto University, 2016. http://hdl.handle.net/2433/216190.
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Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第19936号
農博第2186号
新制||農||1044(附属図書館)
学位論文||H28||N5009(農学部図書室)
33022
京都大学大学院農学研究科森林科学専攻
(主査)教授 木村 恒久, 教授 西尾 嘉之, 教授 髙野 俊幸
学位規則第4条第1項該当
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Fertey, Pierre. "Adaptation de la diffraction des rayons X par des poudres à l'étude des transitions de phases structurales entre 3K et 470K : application à l'étude des corrélations entre propriétés électroniques et structurales dans le composé organique (TMTSF)2ClO4." Université Joseph Fourier (Grenoble ; 1971-2015), 1995. http://www.theses.fr/1995GRE10196.
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La premiere partie est consacree a une revue des developpements de la technique experimentale de la diffraction des rayons x par des echantillons polycristallins (methode des poudres). Il est ici demontre que cette technique est aujourd'hui une methode pertinente pour l'analyse des proprietes structurales des materiaux. Dans une seconde partie, une application originale de la methode des poudres est presentee: un diffractometre de haute resolution fonctionnant entre 3 k et 470 k, a ete concu puis realise, pour l'analyse des contributions structurales dans les mecanismes regissant les transitions de phases (resolution des structures cristalline, mesure de la dilatation thermique, mise en evidence de transitions de phases/distorsions structurales). Les caracteristiques et les performances de ce diffractometre a temperature controlee sont exposees a travers plusieurs applications (transitions de phases avec deux parametres d'ordre correles, temperature de debye). La troisieme partie illustre une etude par diffraction des rayons x a toute temperature, qui a permis l'analyse du role determinant de la mise en ordre des anions c10 (a t = 24 k) sur l'etat fondamental (supraconducteur ou isolant) du compose organique unidimensionnel (tmtsf)#2c10#4. L'influence des deformations elastiques du reseau cristallin sur les proprietes geometriques de la surface fermi sont ainsi rapportees et correlees aux proprietes electroniques observees a basse temperature
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Krogh, Andersen Anne. "Studies of Inorganic Layer and Framework Structures Using Time-, Temperature- and Pressure-Resolved Powder Diffraction Techniques." Doctoral thesis, Stockholm University, Department of Physical, Inorganic and Structural Chemistry, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-23.
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This thesis is concerned with in-situ time-, temperature- and pressure-resolved synchrotron X-ray powder diffraction investigations of a variety of inorganic compounds with twodimensional layer structures and three-dimensional framework structures. In particular, phase stability, reaction kinetics, thermal expansion and compressibility at non-ambient conditions has been studied for 1) Phosphates with composition MIV(HPO4)2·nH2O (MIV = Ti, Zr); 2) Pyrophosphates and pyrovanadates with composition MIVX2O7 (MIV = Ti, Zr and X = P, V); 3) Molybdates with composition ZrMo2O8. The results are compiled in seven published papers and two manuscripts.
Reaction kinetics for the hydrothermal synthesis of α-Ti(HPO4)2·H2O and intercalation of alkane diamines in α-Zr(HPO4)2·H2O was studied using time-resolved experiments. In the high-temperature transformation of γ-Ti(PO4)(H2PO4)·2H2O to TiP2O7 three intermediate phases, γ'-Ti(PO4)(H2PO4)·(2-x)H2O, β-Ti(PO4)(H2PO4) and Ti(PO4)(H2P2O7)0.5 were found to crystallise at 323, 373 and 748 K, respectively. A new tetragonal three-dimensional phosphate phase called τ-Zr(HPO4)2 was prepared, and subsequently its structure was determined and refined using the Rietveld method. In the high-temperature transformation from τ-Zr(HPO4)2 to cubic α-ZrP2O7 two new orthorhombic intermediate phases were found. The first intermediate phase, ρ-Zr(HPO4)2, forms at 598 K, and the second phase, β-ZrP2O7, at 688 K. Their respective structures were solved using direct methods and refined using the Rietveld method. In-situ high-pressure studies of τ-Zr(HPO4)2 revealed two new phases, tetragonal ν-Zr(HPO4)2 and orthorhombic ω-Zr(HPO4)2 that crystallise at 1.1 and 8.2 GPa. The structure of ν-Zr(HPO4)2 was solved and refined using the Rietveld method.
The high-pressure properties of the pyrophosphates ZrP2O7 and TiP2O7, and the pyrovanadate ZrV2O7 were studied up to 40 GPa. Both pyrophosphates display smooth compression up to the highest pressures, while ZrV2O7 has a phase transformation at 1.38 GPa from cubic to pseudo-tetragonal β-ZrV2O7 and becomes X-ray amorphous at pressures above 4 GPa.
In-situ high-pressure studies of trigonal α-ZrMo2O8 revealed the existence of two new phases, monoclinic δ-ZrMo2O8 and triclinic ε-ZrMo2O8 that crystallises at 1.1 and 2.5 GPa, respectively. The structure of δ-ZrMo2O8 was solved by direct methods and refined using the Rietveld method.
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Karlsson, Dennis. "Residual stress in CVD coatings : Evaluation of XRD and TEM methods for micro and macrostress determination." Thesis, Uppsala universitet, Tillämpad materialvetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-269050.
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Cutting tools are subject to extreme environment during processing, with hightemperatures and pressures. CVD coatings are used to increase lifetime andperformance of the WC/Co composite. Residual stresses in the coatings areinteresting as they may be destructive or constructive for the material duringoperation. Blasting is used to change the as-deposited tensile stress to compressive.The usefulness of X-ray diffraction (XRD) and nanobeam diffraction (NBD) forcharacterization of strains in the different coating layers has been investigated. XRDwith different anode materials has been used to determine the macrostress in thelayers and an attempt was done to calculate the average microstrain and crystallitesize. NBD was used to study the microstrain within single grains of the differentmaterials. A specimen preparation method has been developed for the studiedsamples using the FIB.The XRD analysis shows that the measurement condition is of great importanceduring stress measurements. The macrostress of the different samples show that theZrCN type coating is less stressed than the TiCN type coating after deposition. It isalso shown that the ZrCN type coating is less affected by the blasting. Determinationof microstrain and crystallite size from XRD needs further development.The NBD is a good method to evaluate microstrain within single grains, or betweengrains oriented in the same zone axis. The analyses show more strain within thegrains after blasting. The measurements indicate more strain variation in the Al2O3layer in the TiCN system compared to the ZrCN system.
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Runcevski, Tomce [Verfasser], and Robert E. [Akademischer Betreuer] Dinnebier. "Application of in situ X-ray powder diffraction in solid state processes visualization / Tomce Runcevski. Betreuer: Robert E. Dinnebier." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2015. http://d-nb.info/1067843868/34.
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OLIVEIRA, TEREZINHA FERREIRA DE. "ANALYSIS OF THE UNCERTAINTIES OF THE QUANTITATIVE PHASE ANALYSIS BY X-RAY POWDER DIFFRACTION BASED ON THE RIETVELD METHOD." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2005. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=6377@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIORUNIVERSIDADE FEDERAL DA BAHIA
A análise de sistemas de medição consiste do exame da adequação do sistema quanto ao operador, ao instrumento e a outras fontes de variação, bem como da comparação da variância do erro de medição com a variância natural do processo. Nesse aspecto, esta pesquisa teve por objetivo a análise das incertezas da quantificação de fase pelo método de Rietveld em análise de pó. Os efeitos de vários fatores na quantificação de fase foram avaliados utilizando técnicas estatísticas de planejamento experimental e de análise multivariada, com a utilização de materiais de alto nível de rastreabilidade na realização dos experimentos, no Laboratório de difração de raios X do Departamento de Ciências de Materiais e Metalurgia da PUC-Rio. Através da determinação do construto de variação do processo, constatou-se que a quantificação das fases analisadas sofre influência das condições de medição de forma diferenciada de material para material, impossibilitando a obtenção de uma fórmula geral para cálculo dos erros de quantificação, embora os erros possam ser determinados por uma análise de repetitividade e reprodutibilidade apropriadamente conduzida.
The analysis of measurement systems is done by the examination of the adequacy of the system according to the operator, the instrument and other sources of variability, as well as by the comparison of the measurement error variance with the natural process variance. This research consisted in the evaluation of the uncertainties of phase quantification in powder analysis by the Rietveld method. The evaluation of the effects of several factors on the phase quantification was performed using statistical techniques of design of experiments and of multivariate analysis, with the use of materials of high level of traceability for the conduction of the experiments, in the Laboratory of X-ray Diffraction of the Pontifícia Universidade Católica do Rio de Janeiro. Through the determination of the variational structure of the process it was verified that the analyzed phases suffer influence of the measurement conditions in a differentiated way, which prevents the obtention of a general formula for calculation of the quantification error, although the errors can be determined by a repeatability and reproducibility analysis properly conducted.
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Chen, Hong. "Open-framework Structures Built by Inorganic Clusters : Synthesis and Characterization." Doctoral thesis, Stockholms universitet, Institutionen för material- och miljökemi (MMK), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-106853.
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Novel open-framework germanates and vanadoborates, which are constructed from typical types of clusters, have been synthesized based on different strategies. The crystal structures are solved by using single crystal X-ray diffraction (SXRD) technique or by combined techniques. Additionally, the structures of two open-framework materials, PKU-3 and PKU-16, are determined from nano-sized crystals by rotation electron diffraction (RED) combined with powder X-ray diffraction (PXRD). This thesis serves as an introduction to synthesis of open-framework germanates and vanadoborates based on different design strategies. Two germanates are obtained; SU-74 is achieved by employing a novel structure directing agent (SDA), SUT-8 is achieved by assembling the novel structure building units (SBUs) of Co@Ge14 with the introduction of cobalt ions in the synthesis. Four strategies are successfully used in construction of open-framework vanadoborates: using metal-oxo polyhedra as the linkages in SUT-6; applying the scale chemistry approach in SUT-7; employing metal-organic complexes as the linkages in SUT-12, SUT-13, SUT-14; and introducing covalent bond organic linkages into SUT-10 and SUT-11. Single crystal X-ray diffraction is used to conduct the structure determination in combination with other techniques. Furthermore, the structures of two open-framework materials, an aluminoborate PKU-3 and a germanosilicate PKU-16, are solved from nano-sized crystals using RED data. The structures are further confirmed by Rietveld refinement against PXRD data. The advantages of the RED techniques are demonstrated in two aspects. In PKU-3, the presence of seriously preferred orientation and light elements in the structure makes it difficult for structure determination by PXRD, but it is easier by RED. In PKU-16, the RED technique is used to determine its structure from the as-synthesized multi-phasic sample containing nano-sized crystals. After the structure of PKU-16 has been solved, the synthesis of this interesting phase can be optimized and pure PKU-16 can be obtained. Keywords: Open-framework, germanates, vanadoborates, aluminoborates, germanosilicates, crystal structure, hydrothermal synthesis, single crystal X-ray diffraction, rotation electron diffraction, powder X-ray diffraction
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Rajiv, Paneerselvam [Verfasser], and Manfred [Akademischer Betreuer] Joswig. "Automated parametric Rietveld refinement and its application to two dimensional X-ray powder diffraction experiments / Rajiv Paneerselvam. Betreuer: Manfred Joswig." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2011. http://d-nb.info/1016874731/34.
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Beyerlein, Kenneth Roy. "Simulation and modeling of the powder diffraction pattern from nanoparticles: studying the influence of surface strain." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41211.
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Accurate statistical characterization of nanomaterials is crucial for their use in emerging technologies. This work investigates how different structural characteristics of metal nanoparticles influence the line profiles of the corresponding powder diffraction pattern. The effects of crystallite size, shape, lattice dynamics, and surface strain are all systematically studied in terms of their impact on the line profiles.
The studied patterns are simulated from atomistic models of nanoparticles via the Debye function. This approach allows for the existing theories of diffraction to be tested, and extended, in an effort to improve the characterization of small crystallites. It also begins to allow for the incorporation of atomistic simulations into the field of diffraction. Molecular dynamics simulations are shown to be effective in generating realistic structural models and dynamics of an atomic system, and are then used to study the observed features in the powder diffraction pattern.
Furthermore, the characterization of a sample of shape controlled Pt nanoparticles is carried out through the use of a developed Debye function analysis routine in an effort to determine the predominant particle shape. The results of this modeling are shown to be in good agreement with complementary characterization methods, like transmission electron microscopy and cyclic voltammetry.
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Barnes, Paris W. "Exploring structural changes and distortions in quaternary perovskites and defect pyrochlores using powder diffraction techniques." Columbus, Ohio : Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1064346592.
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Thesis (Ph. D.)--Ohio State University, 2003.Title from first page of PDF file. Document formatted into pages; contains xxvi, 255 p.; also includes graphics. Includes abstract and vita. Advisor: Patrick M. Woodward, Dept. of Chemistry. Includes bibliographical references (p. 221-228).
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Swann, Nichola Jean. "Time-resolved studies of the crystallisation and dehydration of lactose and other hydrates using synchrotron X-ray and neutron powder diffraction techniques." Thesis, Keele University, 2015. http://eprints.keele.ac.uk/4216/.
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In-situ time-resolved synchrotron X-ray and neutron powder diffraction techniques have been applied to the study of solid state structural transitions within the organic polymorphic molecular systems of lactose, trehalose and theophylline. Diffraction techniques offer an unequalled method of polymorph identification and quantification, and have repeatedly demonstrated throughout this work that they can be utilised to follow and kinetically evaluate structural transitions in real time. The study of lactose crystallisation provides further proof of the transient ( lo::1/3) mixed crystal polymorph as the initial crystallisation product, which is then followed by the typical beta lactose and alpha lactose monohydrate phases. The formation of the (lo:: l,B) mixed crystal form has been mapped and kinetically analysed; the complex multi-step crystallisation behaviour is likely to result from the high degree of polymorphism which is displayed within the lactose system. The dehydration studies of the three systems show that dehydration kinetics can vary as a function of processing conditions and environments. Evidence of a previously undocumeuted theophylline polymorph has been observed which is accessible via the seeded dehydration of theophylline monohydrate with anhydrous theophylline form II. The best production of beta lactose from the 1-biannual dehydration of alpha lactose monohydrate to date is documented and is attained from dehydration within a hydrophobic cocoa butter environment; this transition is mediated via a crystalline phase whose identity is uncertain, yet displays a unique Bragg peak at rv 12.87° 20. Neutron diffraction techniques reveal that the water content and crystalline weight fraction of trehalose dihydrate are decoupled quantities, and the dihydrate lattice can sustain substantial water loss. These observations provide supporting evidence of a transiently stable, partially hydrated state of trehalose. In addition, the applicability of the Dl9 single-crystal diffraction beamline at the Institut Laue-Langevin in the study of hydrated powder samples is reported, demonstrating the versatility of the instrument with the capability of performing dynamic studies with a time-resolution of 15 s.
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Stuart, Kevin L. "Discovery of Possible Paleotsunami Deposits in Pangandaran and Adipala, Java, Indonesia Using Grain Size, XRD, and 14C Analyses." BYU ScholarsArchive, 2018. https://scholarsarchive.byu.edu/etd/6719.
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Grain size, 14C age, and X-ray diffraction (XRD) analyses of sediments indicate possible tsunami deposits on the southern coast of Java near Pangandaran and Adipala. Previous studies that have described known recent and paleotsunami deposits were used for comparison. Fining-upward grain size trends, interbedded sand and mud, sediment composition, and trends in heavy mineral abundances are among the characteristics used for tsunami deposit identification. At Batu Kalde, an archaeological site south of Pangandaran, a layer of aragonitic sand with marine fossils was found atop a layer of archaeological fragments at an elevation of ~2-5 m. It is likely this layer was deposited by a tsunami, potentially generated by a mega-thrust earthquake. Archaeological material remains suggest that the tsunami occurred ~1300 years ago. A bivalve with an age of 5584-5456 cal YBP was buried within the deposit, perhaps long after its death. At Goa Panggung, a cave east of Batu Kalde, fining-upward grain size trends, composition of sediments, and radiocarbon ages suggest the presence of at least one tsunami deposit. A 5040-4864 cal YBP piece of charcoal overlying modern organic matter suggest that the tsunami first scoured the cave floor, reworking existing material and making interpretation difficult. At Adipala, in western Central Java, fining-upward grain size, upward decrease in heavy mineral abundances, and lateral continuity of sand layers revealed the existence of two possible tsunami deposits buried within the sediments in a swale ~1.6 km from the ocean. Age of the deposits is undetermined.
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Klvač, Ondřej. "Návrh a testování přípravku pro post-mortem XRD měření elektrod li-ion baterií v inertní atmosféře." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2020. http://www.nusl.cz/ntk/nusl-413242.
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The work describes the design and manufacturing of a test device for post-mortem measurements of electrodes of electrochemical cells using X-ray diffraction spectroscopy. The theoretical part describes the diffractometer Rigaku Miniflex 600, for which the product is intended. At the same time, an overview of solutions in various applications is processed here in the form of a recherche. The practical part documents the current development of a new cell, on which tests were performed. Here is an overview of the influence of gases and insulating materials on the resulting data, especially distortion and attenuation. Subsequently, a new design with improved hermetic insulation and sample displacement error correction is described. The principle of operation of the manufactured cell, including the control unit and software, is elaborated in the form of technical documentation. Finally, the functionality is verified by comparing the diffractograms of the powder standards and the graphite electrodes.