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1
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.
2
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)<br>0048<br>新制・課程博士<br>博士(農学)<br>甲第19936号<br>農博第2186号<br>新制||農||1044(附属図書館)<br>学位論文||H28||N5009(農学部図書室)<br>33022<br>京都大学大学院農学研究科森林科学専攻<br>(主査)教授 木村 恒久, 教授 西尾 嘉之, 教授 髙野 俊幸<br>学位規則第4条第1項該当
3
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.
4
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 SUPERIOR<br>UNIVERSIDADE FEDERAL DA BAHIA<br>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.<br>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.
5
Santarelli, Xenja. "Development of capabilities for "in situ" analysis of nanoparticles at the MCX powder diffraction beamline." Doctoral thesis, Università degli studi di Trieste, 2011. http://hdl.handle.net/10077/4479.
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2009/2010<br>Riassunto
Presso la linea di diffrazione MCX (Material Characterization by X-ray diffraction) del Sincrotrone di Trieste e' stata messa a punto una stazione sperimentale che consente di eseguire analisi "in situ" di nanostrutture. Il sistema e' indipendente dal diffrattometro e consente di ottenere in tempi ridotti (grazie all’uso di un Imaging Plate come detector) pattern di diffrazione da polveri o film sottili. La stazione sperimentale e’ dotata di un forno che puo’ riscaldare i campioni fino a 1000ºC. Inoltre e' stato implementato un sistema che consente il flusso di gas attraverso i campioni (contenuti in capillari di vetro o quarzo). L'interfacciamento e' stato realizzato attraverso il software Labview. La struttura e’ stata collocata su un tavolo mobile per agevolarne lo spostamento nell'hutch solo quando necessario. Nel 2009 e' stata accolta l’utenza che ha portato a termine le prime misure. Sono previste le necessarie modifiche che daranno la possibilita' di usare la stazione anche per misure SAXS e di reazioni catalitiche.
Abstract
An Experimental Station has been set up at the MCX (Material Characterization by X-ray diffraction) beamline at the Italian National Synchrotron Radiation facility ELETTRA (Trieste, Italy). The main goal of the system is the possibility to perform “in situ” analysis of nanostructures. This new capability is independent of the diffractometer (an Imaging Plate has been chosen as a detector) and allows to reduce the required times to obtain diffraction patterns from powder samples and thin films. The Experimental Station is equipped with a furnace that heats the samples till 1000ºC, while the implementation of a gas line allows to flow gases through the samples (placed in glass or quartz capillaries). A Labview program has been developed to control the system. The system is located on a wheeled table, so it can be easily moved inside and outside the hutch only when necessary. In 2009, the first users performed their experiments by using this experimental station. Some developments are planned to allow both Small Angle X-ray Scattering (SAXS) experiments and to follow sample behaviour during catalytic reactions.<br>XXIII Ciclo<br>1975
6
Beyerlein, Kenneth Roy. "Simulation and Modeling of the Powder Diffraction Pattern from Nanoparticles: Studying the Effects of Faulting in Small Crystallites." Doctoral thesis, Università degli studi di Trento, 2011. https://hdl.handle.net/11572/368693.
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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 faulting 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.
7
Fawad, Salman Kohar. "Quantitative analysis of multi-phase systems -steels with mixture of ferrite and austenite." Thesis, Linköping University, The Department of Physics, Chemistry and Biology, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-2681.
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<p>The goal of this work has been to evaluate the different experimental techniques used for quantitative analysis of multi-phase materials systems. </p><p>Powder based specimens containing two-phases, austenite and ferrite , were fabricated and quantified. The volume fraction of ferrite varied from 2 Vol% to 50 Vol%. </p><p>X ray powder diffraction (XRD) measurements were based on two peak analysis. Computer based software Topas was used for quantitative analysis, which is believed to be the most advanced in this field. XRD results were found within the absolute limit of +/- 4% of given ferrite volume fraction. Volume fraction as low as 2 Vol% was successfully detected and quantified using XRD. However, high statistical error was observed in case of low volume fraction, such as 2 Vol% and 5 Vol% ferrite volume fraction. </p><p>Magnetic balance (MB) measurements were performed to determine the volume fraction of magnetic phase, ferrite. MB results were found in good agreement with given volume fractions. As low as 2 Vol% volume fraction was detected and quantified with MB. MB results were within the absolute limit of +/- 4% of given ferrite volume fraction. </p><p>Image analysis (IA) was performed after proper sample preparation as required by electron backscatter diffraction (EBSD) mode of Scanning electron microscopy (SEM). IM results were found within the absolute limit of +/- 2 % of given ferrite volume fraction. However, high statistical error was observed in case of 2 Vol% volume fraction.</p>
8
Muroyama, Norihiro. "Studies of inorganic crystal structures and gas adsorption process in mesoporous crystals : new approach through analysis of electron charge distribution by synchrotron powder X-ray diffraction /." Stockholm : Department of Physical, Inorganic and Structural Chemistry, Stockholm university, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-7367.
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Fullagar, Wilfred Kelsham, and w_fullagar@hotmail com. "Molecular Fullerides." The Australian National University. Research School of Chemistry, 1997. http://thesis.anu.edu.au./public/adt-ANU20010831.150750.
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The closed shell structures of certain all-carbon fragments originally observed in mass spectroscopy experiments leads to the enhanced stability of these species, known as fullerenes, which have excited sufficient interest amongst chemists and physicists over the last decade to warrant the award of the 1996 Nobel Prize for Chemistry to their discoverers.
¶
Studies of the stability, symmetry, and consequent remarkable properties of fullerenes began in earnest in 1991 with the development of a technique enabling the production and purification of macroscopic quantities of material. The best known and most widely studied fullerene is the truncated icosahedral C[subscript 60] molecule, which forms the basis of the present work.
¶
One important property of C[subscript 60] is that it forms salts with sufficiently electropositive species, such as the alkali metals. The resulting salts contain C[subscript 60] anions and are known as fullerides. Certain of these salts display metallic behaviour, and some superconduct at temperatures as high as 33 K.
¶
Three aspects of fulleride research are addressed in this work. These are: i) the preparation, crystal structure determination and superconductivity characterization of several new fullerides, particularly those including ammonia as an additional intercalant; ii) the electronic structure of the C[superscript n-, subscript 60] (n = 1 - 6) anions, as probed by solution-phase near infrared absorption spectroscopy; and iii) the molecular dynamics of a number of fullerides, superconducting and non-superconducting, by inelastic neutron scattering.
¶
This work has grown out of an Honours project also concerning C[subscript 60], the combined duration of the two studies covering essentially the entire history of this widely and competitively studied field.
10
Kifune, Koichi, Miho Fujita, Mitsuru Sano, Motoharu Saitoh, and Koh Takahashi. "Electrochemical and Structural Properties of a 4.7 V-Class LiNi0.5Mn1.5 O 4 Positive Electrode Material Prepared with a Self-Reaction Method." The Electrochemical Society, 2004. http://hdl.handle.net/2237/18424.
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Arrué-Muñoz, Ramón. "Magnétisme coopératif dans des composés de coordination à base de Cu(II), Ni(II) et Co(II) et ligands imidazole carboxyliques." Thesis, Rennes 1, 2014. http://www.theses.fr/2014REN1S113/document.
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La présente thèse traite de la synthèse à température ambiante et pression atmosphérique de différents composés de coordination hybrides organique-inorganiques. La partie inorganique de ces composés est constituée d’éléments de transition de la première période 3dn divalents: cobalt, nickel et cuivre. Les ligands utilisés constituent la partie organique de ces composés. Les ligands employés sont l’acide-1H-imidazol-4-carboxilique (H2IMC) et l’acide-1H-imidazol-4,5-dicarboxílique (H3IMDC). La composante inorganique Mx+ est introduite dans le composé terminal en utilisant le précurseur métallique moléculaire M(hfac)2 (M = Cu2+, Co2+, Ni2+; hfac = 1,1,1,5,5,5- hexafluoro-2,4-pentanodione), précurseur utilisé afin d'obtenir un centre métallique acide facile à coordonner aux ligands imidazol carboxíliques dans des positions axiales. L’ensemble des composés a été caractérisé par l’étude des propriétés magnétiques, études thermogravimétriques et caractérisation structurale (résolution et affinement) sur échantillons pulvérulents. Dans la totalité des structures obtenues, le ligand imidazol carboxylique se lie à l’espèce métallique en positions équatoriales via l’élément azote du cycle et un élément oxygène du groupement carboxylique. Les mesures magnétiques montrent des déviations à la loi de Curie à basse température qui indiquent des phénomènes de coopération magnétique entre les centres métalliques. Ces centres métalliques ont été traités et modélisés en considérant, pour les composés contenant les éléments cuivre et nickel, un modèle de chaîne régulière qui a permis d’estimer la constante d’interéchange J. Pour les composés contenant l’élément cobalt, seule l’importante contribution orbitale (L≠ 0) à la propriété magnétique (état fontamental 4T1g en symétrie octaédrique) sans interaction inter espèces magnétiques a été prise en considération pour traiter les données<br>This thesis work presents the synthesis at ambient temperature and pressure of different hybrids organic - inorganic coordination compounds. The inorganic portion is composed by transition elements from the first period 3dn divalent cobalt, nickel and copper. The selected ligands are the organic portion of these compounds, and there are the 1H-imidazol-4-carboxylic acid (H2IMC) and 1H-imidazole-4,5-dicarboxylic acid (H3IMDC)2. The inorganic component Mx+ is introduced into the terminal compound by using the molecular metallic precursor M(hfac)2 (M=Cu2+, Co2+, Ni2+; hfac=1,1,1,5,5,5-hexafluoro-2,4-pentanodione) used to obtain an acidic metal center that coordinates easily to imidazol carboxylic ligands in axial positions. All compounds were characterized by studying their magnetic properties, thermogravimetric analysis and structural characterization (resolution and refinement) on powdered samples. In all these compounds, the imidazole carboxylic ligand is linked to the central metal ion in equatorial position, by the nitrogen atom from the imidazole ring, and an oxygen atom from the carboxylic group. The magnetic measurements have revealed deviations at low temperatures to the Curie law, suggesting magnetic cooperation phenomena between the metallic centers. For the copper and nickel based compounds, the magnetic data was analyzed considering a regular chain model that has led to obtain the value of the exchange coupling constant J. For the cobalt based compounds the treatment has been different. Only the important orbital contribution (L≠ 0) to the magnetic propierties (fundamental state 4T1g for octahedral symmetry) without interaction between the metallic centers was taken into account for the data treatment<br>La presente tesis trata de la síntesis a temperatura ambiente y presión atmosférica de diferentes compuestos de coordinación híbridos órgano-inorgánicos. La parte inorgánica de estos compuestos está constituida por los elementos de transición divalentes del primer período 3dn: cobalto, níquel y cobre. Los ligandos utilizados constituyen la parte orgánica de estos compuestos. Los ligandos empleados son el ácido-1H-imidazol-4-carboxílico (H2IMC) y el ácido-1H-imidazol-4,5-dicarboxílico (H3IMDC). La componente inorgánica Mx+ ha sido introducida en los compuestos terminales utilizando el precursor metálico molecular M(hfac)2 (M = Cu2+, Co2+, Ni2+; hfac = 1,1,1,5,5,5-hexafluoro-2,4-pentanodiona), precursor utilizado con el fin de obtener un centro metálico ácido fácil de ser coordinado por los ligandos imidazol carboxílicos en las posiciones axiales. El conjunto de los compuestos obtenidos ha sido caracterizado mediante el estudio de sus propiedades magnéticas, análisis termogravimétrico y caracterización estructural (resolución y afinamiento) sobre muestras pulverizadas. En la totalidad de la estructuras obtenidas, el ligando imidazol carboxílico se une al metal en posiciones ecuatoriales a través del átomo de nitrógeno del anillo imidazol y un átomo de oxígeno del grupo carboxílico. Las medidas magnéticas muestran desviaciones de la ley de Curie a baja temperatura que indican fenómenos de cooperación magnética entre los centros metálicos. Estos centros metálicos han sido tratados y modelados considerando para los compuestos de cobre y níquel, un modelo de cadena regular que ha permitido estimar el valor de la constante de intercambio J. Para los compuestos de cobalto, se ha considerado la importante contribución orbital (L≠ 0) a la propiedad magnética (estado fundamental 4T1g en simetría octaédrica) sin interacción entre las especies magnéticas para el tratamiento de los datos
12
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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Weston, Laura. "Computational characterisation of organic molecules for electronic applications and an experimental study of cocrystals for electronic devices." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/computational-characterisation-of-organic-molecules-for-electronic-applications-and-an-experimental-study-of-cocrystals-for-electronic-devices(0d1a24ea-3241-40cf-bafa-6be179ba4c26).html.
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A range of small molecules of interest for use in organic semiconductor devices were studied computationally. Trends in geometry, absorption spectra, molecular orbitals, electrostatic potentials, reorganisation energies were studied. Results suggest that, as with acenes, the performance of non-linear cata-condensed polyaromatic hydrocarbons improves as number of fused benzene rings increases. The torsion in these molecules did not appear to have a large impact on the conjugation across the core and little effect on the absorption spectra, although it did affect the reorganisation energies on which charge mobilities depend. Computational studies of mobilities of anthradithiophene molecules were broadly able to reproduce trends seen experimentally and emphasised the importance of crystal morphology. Experimental work was also carried out to search for cocrystals between anthradithiophene derivatives. Many examples were found with some mixtures forming different cocrystals at different mixture ratios. These results were rationalised by a computational study that showed molecules which had a similar binding energy were more likely to be able to form cocrystals. Cocrystal devices were fabricated and 3 out of 7 showed a larger mobility than devices made out of its constituent materials alone. The best of these had a mobility 65% higher than a device made out of the constituent material with the largest mobility. An energy decomposition analysis was carried out on a novel thallophilic system, a complex of thallium with a neutral β-triketimine ligand which was found to form dimers with close Tl-Tl interactions. Calculations show the electrostatic interaction to be repulsive for the dimer with no counter ions, but attractive when 3,5-bistrifluoromethylphenyl borate counter ions are included. This suggests the metallophilic interaction is counter ion-mediated, requiring the anions to provide favourable electrostatics, even in the case of spatially diffuse and distant counter ions such used here. To enable the studies described here software was written for simulating absorption spectra. An implementation into the Gaussian Suite of programs of an energy decomposition scheme and its extension to include an empirical dispersion correction was also carried out.
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FALCAO, RAILSON B. "Síntese por reação do TiFe nanoestruturado para o armazenamento de hidrogênio, a partir da moagem de alta energia de misturas de pós de TiH2 e Fe." reponame:Repositório Institucional do IPEN, 2016. http://repositorio.ipen.br:8080/xmlui/handle/123456789/27135.
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Submitted by Mery Piedad Zamudio Igami (mery@ipen.br) on 2017-03-10T16:23:34Z
No. of bitstreams: 0<br>Made available in DSpace on 2017-03-10T16:23:34Z (GMT). No. of bitstreams: 0<br>Neste trabalho investigou-se a obtenção do composto TiFe a partir da moagem de alta energia de misturas de pós de TiH2 e Fe, seguida de aquecimento sob vácuo para a reação de síntese. No lugar do Ti, o TiH2 foi escolhido como precursor em razão de sua fragilidade, benéfica para a diminuição da aderência dos pós ao ferramental de moagem. Foram preparados dois lotes de misturas obedecendo-se a relação Ti:Fe de 50:50 e 56:44. Ambos foram processados em um moinho do tipo planetário por tempos que variaram de 5 até 40 horas, sob atmosfera de argônio de elevada pureza. Em todos os experimentos foram mantidos constantes a velocidade de rotação do prato do moinho, a quantidade de amostra, o diâmetro e o número de bolas. As amostras moídas foram caracterizadas por calorimetria exploratória diferencial (DSC), termogravimetria (TG), microscopia eletrônica de varredura (MEV), difração de raios X (DRX) e fluorescência de raios X por dispersão de energia (EDXRF). Apenas TiH2 e Fe foram observados nas amostras moídas, com um grau crescente de mistura em função do tempo de moagem. O composto TiFe nanoestruturado (12,5 a 21,4nm) foi obtido de forma majoritária em todas as amostras após a reação de síntese promovida pelo tratamento térmico a 600ºC (873K). As amostras reagidas foram caracterizadas por microscopia eletrônica de transmissão (MET) e DRX. Um equipamento do tipo Sievert, operando sob um fluxo constante (modo dinâmico), foi utilizado para levantar as curvas termodinâmicas de absorção e dessorção de hidrogênio. Todas as amostras absorveram hidrogênio à temperatura ambiente (~298K) sem a necessidade de ciclos térmicos de ativação. Os melhores resultados foram obtidos com as amostras moídas por 25 e 40 horas, de composição não estequiométrica 56:44. Tais amostras absorveram e dessorveram hidrogênio à temperatura ambiente, sob os platôs de aproximadamente 6,4 e 2,2bar (~0,6 e 0,2MPa), respectivamente. A capacidade máxima de armazenamento foi de 1,06% em massa de hidrogênio (H:M~0,546), sob pressão de até 11bar (1,1MPa), com reversão de até 1,085% em massa de hidrogênio (H:M~0,559), sob pressão de até 1bar (0,1MPa). Estas amostras também apresentaram maior cinética de absorção e dessorção de hidrogênio com fluxos de 1,23 (25h) e 2,86cm3/g.min. (40h). Tais resultados são atribuídos à variação composicional da fase TiFe e à maior quantidade de TiH2 livre.<br>Tese (Doutorado em Tecnologia Nuclear )<br>IPEN/D<br>Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
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Ortatatlı, Şeyma [Verfasser], Cuenya Beatriz [Gutachter] Roldán, and Claudia [Gutachter] Weidenthaler. "Monitoring the structures of inorganic materials by \(\textit ex situ/in situ}\) X-Ray powder diffraction and pair distribution function analysis / Şeyma Ortatatlı ; Gutachter: Beatriz Roldán Cuenya, Claudia Weidenthaler ; Fakultät für Physik und Astronomie." Bochum : Ruhr-Universität Bochum, 2018. http://d-nb.info/1160442223/34.
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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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Theiss, Frederick L. "Synthesis and characterisation of layered double hydroxides and their application for water purification." Thesis, Queensland University of Technology, 2012. https://eprints.qut.edu.au/54620/1/Frederick_Thesis.pdf.
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Layered doubly hydroxides (LDHs) also known as hydrotalcites or anionic clays are a group of clay minerals that have shown promise for the removal of toxic anions from water through both anion exchange and a process known as the reformation effect. This project has involved the preparation and characterisation of LDH materials as well as the investigation of their ability to remove selected anions from aqueous solutions by the reformation effect.
The LDH materials were successfully prepared from magnesium, aluminium, zinc and chromium chloride salts using the co-precipitation method. Samples were characterised using powder X-ray diffraction (XRD) and thermogravimetry (TG) to confirm the presence of LDHs. Powder XRD revealed a characteristic LDH structure for all LDH samples. Thermal Analysis showed decomposition usual occurred through a three or four step process as expected for LDHs. Preliminary investigations of the removal of sulfate, nitrate and fluoride by an Mg/Al LDH were carried out, and the products were characterised using XRD and TG which showed that an LDH material similar to the original hydrotalcite was formed after reformation.
A Zn/Al LDH was investigated as a potential sorbent material for the removal of iodine and iodide from water. It was found that the LDH was a suitable adsorbent which is able to remove almost all of the iodine present in the test solutions. Again, the products were characterised by XRD, TG and evolved gas mass spectrometry (EGMS) in an attempt to better understand the iodine removal process. Powder XRD showed successful reformation of the LDH structure and TG/EGMS showed that only a small amount of iodine species were lost during thermal decomposition. Finally, the mineral stichtite a Mg/Cr LDH was successfully synthesised and investigated using XRD, TG and EGMS. Unfortunately, due to lack of time it was not possible to identify any new uses for the mineral stichtite in the current project.
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Ibiapino, Amanda Laura. "Caracterização físico-química dos derivados sulfonilidrazônicos - LASSBio-1773 e LASSBio-1774 - empregados no tratamento do diabetes mellitus tipo 2." reponame:Repositório Institucional da UFABC, 2016.
Find full textAbstract:
Orientador: Prof. Dr. Fabio Furlan Ferreira<br>Tese (doutorado) - Universidade Federal do ABC, Programa de Pós-Graduação em Nanociências e Materiais Avançados, 2016.<br>Diabetes mellitus é um problema de saúde pública com elevado ônus social e econômico. O diabetes mellitus tipo 2 (DM2) é o subtipo mais comum e está presente em 90% a 95% dos casos. Atualmente, pessoas portadoras de DM2 têm apresentado um risco elevado no desenvolvimento de alguns tipos de cânceres, o que gera uma maior preocupação sobre a saúde a nível mundial. Diante do aumento da incidência de portadores da doença a cada ano e do impacto mundial que o diabetes vem atingindo, o propósito principal desta tese consistiu em realizar a caracterização físico-química dos candidatos a fármacos - LASSBio-1773 e LASSBio-1774, ambos os compostos apresentam atividade hipoglicemiante e são efetivos na neuropatia diabética periférica. Além da atividade hipoglicemiante, o LASSBio-1774 apresenta também atividade anti-inflamatória, o que faz do composto extremamente promissor para o tratamento do DM2. A caracterização físico-química dos compostos foi realizada pela difração de raios X por policristais (DRXP), termogravimetria (TG), calorimetria exploratória diferencial (DSC), espectroscopia no infravermelho por transformada de Fourier (FTIR), microscopia eletrônica de varredura (MEV), dissolução intrínseca (DI) e estudos da predição da morfologia dos cristais pelo método GM (growth morphology method). Pelas análises dos padrões de difração foi verificado que os candidatos a fármacos são de moléculas cristalinas e de baixa simetria. No processo de indexação com os dados de DRXP foi observado que os compostos cristalizaram em sistemas ortorrômbicos, porém em diferentes grupos espaciais. O LASSBio-1773 cristalizou no grupo espacial P212121 e o LASSBio-1774 no grupo espacial Pbca. Pela análise dos dados de TG/DTG foi determinada a estabilidade térmica dos compostos. Por meio dos dados de DSC foram determinados a fusão e a pureza dos compostos. Com os dados de DSC, TG e FTIR pôde-se caracterizar o LASSBio-1773 como uma molécula anidra e o LASSBio-1774 como uma molécula monohidratada. Nas fotomicrografias de MEV e nos estudos da predição da morfologia dos cristais foram evidenciados diferentes formas de cristais para os compostos. Pelos ensaios de DI pôde-se classificar o LASSBio-1773 e o LASSBio-1774 monohidratado como compostos de baixa solubilidade.<br>Diabetes mellitus is a public health problem with high social and economic burden. The type 2 diabetes mellitus is the most common type and is present in 90% to 95% of cases. Currently, people with type 2 diabetes mellitus have shown a high risk of developing some types of cancer, which generate a great concern about health on a global level. Given the increasing incidence of individuals with the disease each year and due to the worldwide impact that diabetes has reached, the main purpose of this thesis was to conduct the physicochemical characterization of two parent compounds - LASSBio-1773 and LASSBio-1774, both compounds exhibit hypoglycemic activity and display an anti-neuropathy effect. In addition to the hypoglycemic activity, the LASSBio-1774 also exhibits anti-inflammatory activity, making this compound extremely promising for the treatment of type 2 diabetes mellitus. The physicochemical characterization of the compounds was performed by X-ray powder diffraction (XRPD), thermogravimetry (TG), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), intrinsic dissolution (ID) and studies of morphology prediction by growth morphology method (GM method). The analysis of the diffraction patterns evidenced that the pharmaceutical candidates are crystalline molecules of low symmetry. Both compounds crystallized in orthorhombic space groups ¿ LASSBio-1773 crystallized in the P212121 and LASSBio-1774 in the Pbca space groups. By means of the TG/DTG data we determined the thermal stability of the compounds. By DSC we observed the fusion and purity of the compounds. With the results from DSC, TG and FTIR it was possible to characterize the LASSBio-1773 as an anhydrous molecule and LASSBio-1774 as a monohydrate one. By inspection of the SEM photomicrographs and the studies of crystal morphology prediction we observed different crystal forms for the compounds. By intrinsic dissolution tests we could classify both LASSBio-1773 and 1774-LASSBio monohydrate as low solubility compounds.
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Gonzalez-Santiago, Berenice. "Synthesis and properties of scandium carboxylate metal-organic frameworks." Thesis, University of St Andrews, 2015. http://hdl.handle.net/10023/6904.
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This work investigated the synthesis, characterisation and properties of known and novel scandium carboxylate Metal-organic Frameworks (MOFs). The first part reports the performance of these Sc-MOFs as Lewis acid catalysts. The porous MOF scandium trimesate MIL-100(Sc) and the scandium terephthalates such as MIL-101(Sc), MIL-88B(Sc) and MIL-68(Sc) (prepared as the Sc-analogue for the first time), and scandium biphenyldicarboxylate MIL-88D(Sc) were prepared and tested as Lewis acid catalysts. Chromium MIL-101 and MIL-100 and scandium-exchanged zeolites were prepared for comparison. Moreover, successful encapsulation of the phosphotungstate polyoxometalates (POMs) in the cavities of MIL-101(Sc) enhanced the stability of this material. These scandium and chromium MOFs, POM-MOF composites and scandium-exchanged zeolite were tested as heterogeneous catalysts in the carbonyl ene reaction between α-methyl styrene and ethyl trifluoropyruvate. This showed that MIL-100(Sc) was the best catalyst for this reaction, achieving a conversion of 99% to the desired product. The stabilized MIL-101(Sc) was also very active, but less selective for this reaction. Acetalisation of acetaldehyde was also studied, and in this reaction the isoreticular MOFs MIL-88(B) and MIL-88D(Sc) were the most active and selective catalysts. For this reaction, the activity of MIL-100(Sc) was low, which was attributed to reduce pore size and blockage. Functionalisation of the range of scandium terephthalates such as MIL-101(Sc), MIL-88B(Sc), MIL-68(Sc), Sc₂BDC₃,and MIL-53(Sc) particularly with –NH₂ groups, made up the second main part of this research. Solvothermal synthesis were performed at lower temperatures and using mixed solvents to synthesize these amino-terephthalate MOFs, often for the first time, and their adsorption properties were studied, particularly for the adsorption of CO₂. The synthesis of pure Sc₂(NH₂-BDC)₃ and Sc₂(Br-BDC)₃ was achieved for first time by a solvothermal route, lower temperatures, and mixed solvents. This approach yielded large crystals suitable for single crystal diffraction and microcrystal IR spectroscopy. Post-synthetic modification (PSM) of Sc₂(NH₂-BDC)₃ was explored by incorporation of NO₂-groups into the framework by solvent-assisted ligand exchange. The adsorption properties of functionalised and post-modified materials were compared with those of Sc₂BDC₃ and Sc₂(NO₂-BDC)₃ for methanol and hydrocarbons This study demonstrated that Sc₂BDC₃ and Sc₂(NH₂-BDC)₃ give the higher uptakes while the –Br and –NO₂ forms display shape selectivity for n-alkanes over iso-alkanes. Amino-functionalised MIL-53(Sc) was prepared for the first time using a mixed ligand approach, so that 10-20% of a second functionalised terephthalate ligand (NO₂, Br, -(OH)₂) was required for successful single phase synthesis in addition to amino-terephthalic acid. The materials were characterised using PXRD, TGA and gas adsorption, which confirms the samples show a range of behaviour for CO₂ adsorption. Notably, the `breathing´ behaviour is strongly dependent on the type of functionalisation. Finally, the exploratory synthesis of novel scandium MOFs, using isophthalic acid (IA) and its amino and nitro- derivatives, 2,5-furandicarboxylate (FDA) and the porphyrin tetra(carboxyphenyl)porphyrin (TCPP) as linkers was carried out and six novel materials were synthesized, three of which gave crystals large enough for their structure to be determined by single crystal diffraction. Further characterisation was carried out by PXRD, TGA and solid-state NMR. Some of these materials have been shown to be porous to CO₂ and N₂.
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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, Fe<SUB>3</SUB>O<SUB>4</SUB>, below the Verwey phase transition (120 K). The P2/c structure of Fe<SUB>3</SUB>O<SUB>4</SUB> 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 Fe<SUB>3</SUB>O<SUB>4</SUB> 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 Fe<SUB>3</SUB>O<SUB>4</SUB> around the transition. Chapter 4 describes a structural study on a material related to magnetite, Fe<SUB>2</SUB>OBO<SUB>3</SUB>. 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 (P2<SUB>1</SUB>/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 <I>ab initio </I>structure determination of 4-(2'3'4'-trifluorophenyl)-1235 dithiadiazolyl (C<SUB>7</SUB>S<SUB>2</SUB>N<SUB>2</SUB>F<SUB>3</SUB>H<SUB>2</SUB>; P<SUB>2</SUB>/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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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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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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Leonardi, Alberto. "Molecular Dynamics and X-ray Powder Diffraction Simulations: Investigation of nano-polycrystalline microstructure at the atomic scale coupling local structure configurations and X-ray powder Diffraction techniques." Doctoral thesis, Università degli studi di Trento, 2012. https://hdl.handle.net/11572/368091.
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Atomistic simulations based on Molecular Dynamics (MD) were used to model the lattice distortions in metallic nano-polycrystalline microstructures, with the purpose of supporting the analysis of the X-ray powder diffraction patterns with a better, atomic level understanding of the studied system.
Complex microstructures were generated with a new modified Voronoi tessellation method which provides a direct relation between generation parameters and statistical properties of the resulting model. MD was used to equilibrate the system: the corresponding strain field was described both in the core and in surface regions of the different crystalline domains. New methods were developed to calculate the strain tensor at the atomic scale.
Line Profile Analysis (LPA) was employed to retrieve the microstructure information (size and strain effects) from the powder diffraction patterns: a general algorithm with an atomic level resolution was developed to consider the size effects of crystalline domains of any arbitrary shape. The study provided a new point of view on the role of the grain boundary regions in nano-polycrystalline aggregates, exploring the interference effects between different domains and between grain boundary and crystalline regions. Usual concepts of solid mechanics were brought in the atomistic models to describe the strain effects on the powder diffraction pattern. To this purpose the new concept of Directional - Pair Distribution Function (D-PDF) was developed. D-PDFs calculated from equilibrated atomistic simulations provide a representation of the strain field which is directly comparable with the results of traditional LPA (e.g. Williamson-Hall plot and Warren-Averbach method).
The D-PDF opens a new chapter in powder diffraction as new insights and a more sound interpretation of the results are made possible with this new approach to diffraction LPA.
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Leonardi, Alberto. "Molecular Dynamics and X-ray Powder Diffraction Simulations: Investigation of nano-polycrystalline microstructure at the atomic scale coupling local structure configurations and X-ray powder Diffraction techniques." Doctoral thesis, University of Trento, 2012. http://eprints-phd.biblio.unitn.it/843/1/PhDThesis_ALeonardi.pdf.
Full textAbstract:
Atomistic simulations based on Molecular Dynamics (MD) were used to model the lattice distortions in metallic nano-polycrystalline microstructures, with the purpose of supporting the analysis of the X-ray powder diffraction patterns with a better, atomic level understanding of the studied system.
Complex microstructures were generated with a new modified Voronoi tessellation method which provides a direct relation between generation parameters and statistical properties of the resulting model. MD was used to equilibrate the system: the corresponding strain field was described both in the core and in surface regions of the different crystalline domains. New methods were developed to calculate the strain tensor at the atomic scale.
Line Profile Analysis (LPA) was employed to retrieve the microstructure information (size and strain effects) from the powder diffraction patterns: a general algorithm with an atomic level resolution was developed to consider the size effects of crystalline domains of any arbitrary shape. The study provided a new point of view on the role of the grain boundary regions in nano-polycrystalline aggregates, exploring the interference effects between different domains and between grain boundary and crystalline regions. Usual concepts of solid mechanics were brought in the atomistic models to describe the strain effects on the powder diffraction pattern. To this purpose the new concept of Directional - Pair Distribution Function (D-PDF) was developed. D-PDFs calculated from equilibrated atomistic simulations provide a representation of the strain field which is directly comparable with the results of traditional LPA (e.g. Williamson-Hall plot and Warren-Averbach method).
The D-PDF opens a new chapter in powder diffraction as new insights and a more sound interpretation of the results are made possible with this new approach to diffraction LPA.
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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.<br>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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Sitepu, Husinsyah. "Characterisation of preferred orientation in crystalline materials by x-ray powder diffraction." Thesis, Curtin University, 1991. http://hdl.handle.net/20.500.11937/1897.
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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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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.
Full textAbstract:
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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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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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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Mohamed, Zakiah. "Relationships Among Structure, Magnetism and State of Charge in Positive Electrode Materials for Metal-Ion Batteries." Thesis, The University of Sydney, 2015. http://hdl.handle.net/2123/14438.
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Polyanionic framework materials containing 3d transition metals such as iron, cobalt and manganese are attractive candidates as electrodes in lithium and sodium ion batteries due to their thermal stability, long cycle life and environmental friendliness. LiFePO4 is already used in some commercial lithium ion batteries as a positive electrode material where these are key attributes, but it still has lower energy density and higher costs compared to the more commonly used LiCoO2. This thesis describes a combined physical properties and magnetic structures some of these materials, aimed at improving our understanding of their solid-state chemistry, and ultimately their performance as battery materials by relating those physical and magnetic properties to the state of charge of the battery. A variety of polyanionic materials including phosphates, pyrophosphates and silicates were prepared using solid-state synthesis. All compounds were intensively characterized using specific heat capacity and magnetic measurements, X-ray, neutron and synchrotron X-ray diffraction techniques. Low-temperature neutron diffraction was used to solved and refined the magnetic structures. During the lithium extraction process, the magnetic properties can vary significantly because it involve redox reaction of transition metals. Measuring the magnetic properties of working electrode materials can therefore potentially provide information about local structural changes including the introduction of defects, decomposition and phase segregation. The magnetic properties of chemically delithiated samples were also studied so that they could be used as reference materials. In the first part of the thesis, the phosphates family AM1-xM′xPO4 (A = Li, Na; M = Mn, Fe; M′ = Zn, Mn, Fe) are intensively studied. These phosphates are modified in two ways: by doping with magnetic and non-magnetic transition metals. It was found that all compounds exhibit antiferromagnetic ordering at low temperatures, but the nature and ordering temperatures depend on doping. In the course of this work, the magnetic structures of two types of sodium phosphate were determined for the first time,triphylite and maricite NaFePO4. The triphylite type showed similar crystal and magnetic properties as LiFePO4, while the maricite type demonstrated a transition from commensurate (T < 12 K) to incommensurate (12 < T < 13 K) magnetic phases. A spin-flop transition in the commensurate phase was also observed. These results are discussed in the context of spin frustration on the Fe2+ sites. The second type of cathode material studied was the pyrophosphate A2M1-xM′xP2O7 (A = Li, Na; M = Fe; M′ = Co, Mn). Varying the compositions of these materials led to significant changes in crystallographic and electronic structure with remarkable effects on the magnetic properties and structures.The magnetic structures of Li2(Fe1-xCox)P2O7 and Na2(Fe1-xMnx)P2O7 solid solutions were explored in the course of this work. The crystal and magnetic structures of the silicates γ-Li2MnSiO4 and β-Li2CoSiO4 were investigated and their magnetic structures solved for the first time, including for chemically delithiated versions of Li2CoSiO4. Magnetic property measurements confirmed that Co had oxidised from Co2+ to Co3+, confirming that delithiation was successful while also serving to demonstrate the sensitivity of magnetic measurements to lithium content. In addition, the structural evolution of Li2CoSiO4 was tracked by in situ S-XRD and revealed no phase transformation during cycling. In summary, the outcome of this study is an extension of the state of knowledge of the low-temperature magnetic properties and structures of polyanion-based transition metal oxides, and a demonstration of the sensitivity of those properties and structures to electrochemical state. Further refinement of this approach could lead to a new tool for developing improved positive electrode materials for rechargeable batteries. The work also yielded crucial missing information concerning the electronic ground state of these materials, required for future high-level computational studies aimed at predicting properties including ionic conductivity.
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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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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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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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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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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.<br><p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 3: Manuscript.</p>
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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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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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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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Dall'Olio, Laura <1991>. "Survey of methodologies of pharmaceutical interest for quantification of crystal form via X-Ray Powder Diffraction." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amsdottorato.unibo.it/9769/1/Dall%27Olio_Laura_Tesi.pdf.
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The interest on polymorphism of arises from their different properties. A strategy to improve the properties of compound, is the formation of cocrystal. In this PhD project, cocrystal statistical analysis and experimental screening of allantoin and some coformers were performed. No cocrystal was obtained, experimental results disagree with the statistical analysis.
Quantitative method of crystalline forms via X-Ray Powder Diffraction are extremely interesting for pharmaceutical companies. In the thesis real cases with different approaches of quantitative analysis are reported.
I presented the quantification of paracetamol form II impurity in Tachifludec containing paracetamol form I using univariate method in which the main issue is the identification of a specific peak. The presence of several peaks in the formulation was overcome by applying the standard addition method spiking the formulation with form II. Univariate and multivariate method NAS were compared, and the best results were obtained with the application of the multivariate method. These approaches were also evaluated in the case of mixture amorphous-crystalline. Furthermore, it was studied the potential use of stable amorphous surrogate instead to the unstable real amorphous. Even in these cases, multivariate method achieved the best results.
The novel quantification method Direct derivation (DD) based on intensity–composition equation was applied to determine crystallinity of mixture amorphous-crystalline. The quantification method was evaluated in three scenarios: method a) with unit cell parameters, method b) structural information is unknown, and method c) only the mixtures’ patterns are available. Method a and b achieved more accurate results because of better description of the crystalline phase. Method b was evaluated in sample covered by containment system as the Kapton® film to evaluate the analysis of highly potent compounds. The DD method has been revealed the best method to estimate the crystallinity degree of formulation containing highly potent compound deposited on catheter balloon.
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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.<br>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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Lopresti, Mattia. "Non-destructive X-ray based characterization of materials assisted by multivariate methods of data analysis: from theory to application." Doctoral thesis, Università del Piemonte Orientale, 2022. http://hdl.handle.net/11579/143020.
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X-ray based non-destructive techniques are an increasingly important tool in many fields, ranging from industry to fine arts, from medicine to basic research. Over the last century, the study of the physical phenomena underlying the interaction between X-rays and matter has led to the development of many different techniques suitable for morphological, textural, elementary, and compositional analysis. Furthermore, with the development of the hardware technology and its automation thanks to IT advancements, enormous progress has been made also from the point of view of data collection and nowadays it is possible to carry out measurement campaigns by collecting many GigaBytes of data in a few hours. Already huge data sets are further enlarged when samples are analyzed with a multi-technique approach and/or at in situ conditions with time, space, temperature, and concentration becoming additional variables. In the present work, new data collection and analysis methods are presented along with applicative studies in which innovative materials have been developed and characterized. These materials are currently of high application interest and involve composites for radiation protection, ultralight magnesium alloys and eutectic mixtures. The new approaches have been grown up from an instrumental viewpoint and with regard to the analysis of the data obtained, for which the use and development of multivariate methods was central. In this context, extensive use has been made of principal component analysis and experimental design methods. One prominent topic of the study involved the development of in situ analysis methods of evolving samples as a response to different types of gradients. In fact, while in large structures such as synchrotrons carrying out analyzes under variable conditions is now consolidated practice, on a laboratory scale this type of experiments is still relatively young and the methods of data analysis of data sets evolving systems have large perspectives for development especially, if integrated by multivariate methods.