Auswahl der wissenschaftlichen Literatur zum Thema „RTG diffraction“

Ze souboru vzorků obsahujících železo byly metodami Mössbauerovy spektroskopie a rtg difrakční analýzy získána data, na která byla aplikována faktorová analýza, díky níž bylo zjištěno, kolika faktory lze vysvětlit celkový rozptyl dat. Došlo tedy k vyčíslením faktorového skóre, k redukci počtu proměnných a vzniku faktorů, kterými byly nahrazeny původní proměnné. U Mössbauerovy spektroskopie se jedná o šest faktorů, kterým bylo přiřazeno šest původních proměnných a u rtg difrakční analýzy byly zjištěny tři faktory, kterým byly přiřazeny tři původní proměnné.

Article deals with problematic of internal residual stress after machining depends on various cutting condition. In article is presented influenced of cutting conditions to quality of internal layers by defining values of residual stresses. Method use to evaluate values of residual stress was RTG diffraction. Material used for experiment was steel C45 and type of machining was up milling for various parameters such as spindle speed, feed rate and depth of cut.

A new gas dosing rig built for the high-resolution powder diffraction beamline (ID31) at the ESRF is described. The rig is fully controlled and monitored by the beamline control software, enabling automated absorption and desorption of fixed pressures of gases up to 100 bar (107 Pa) forin situstructural studies. The rig has successfully been used on ID31 as well as other beamlines at the ESRF.

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.

This thesis deals with the behavior of cement concrete at high temperature with a focus on the impact behavior of aggregate, cement type and polypropylene fiber reinforcement. The theoretical part describes the issue of cement concrete at high temperatures, especially processes in the cement matrix, aggregates and polypropylene fibers. Furthermore, theoretical part describes the selection of a suitable type of cement and aggregates in concrete exposed to high temperatures. In the experimental part was designed the concrete composition with various kinds different types of aggregates and two types of cements. The temperature stress of test samples was performed according to ISO standard temperature curve 834. Subsequently, was made the verification of the physic-mechanical properties such as changes in bulk density and compressive strength after heat load. Moreover, the surface appearance of samples after heat load was evaluated, especially the occurrence of samples, the crack width and explosive spalling. Mineralogical composition changes of prepared samples before and after heat load were observed via X-ray diffraction analysis. Finally, we made a photogrammetry on a test plates after heat load which defined the size of the area and depth of spalling concrete surface.

Anorthite is crystalline phase in the ceramic body. Is acquired on burning a mixture of calcium ceramic raw material. This work deals with the influence on the resulting properties of anorthite ceramic body, especially flexural strength, porosity, shrinkage, thermal expansion coefficient. And the influence of different CaO sources on the properties. As a source of CaO was used calcium carbonate, calcium hydroxide and fluid fly ash.

[ES] Las zeolitas son materiales cristalinos microporosos con canales y tamaños de poro de dimensiones moleculares. La estructura y composición de las zeolitas les confiere interesantes propiedades que permiten su aplicación en una amplia gama de aplicaciones industriales como adsorción, separación o catálisis. La síntesis de zeolitas es la etapa más importante para el control de la estructura y composición de las zeolitas y, por tanto, crítica para la optimización de sus propiedades. Esta tesis se ha centrado en la síntesis de zeolitas utilizando compuestos que contienen fósforo (cationes fosfonio y aminofosfonio) como Agentes Directores de Estructura (P-ADE). El uso de compuestos fosforados influye en la cristalización y propiedades de las zeolitas obtenidas en comparación con las zeolitas obtenidas con cationes de amonio clásicos. Los compuestos fosforados se eligieron debido a su diferente química y estabilidad con respecto a los cationes de amonio clásicos comúnmente usados en la síntesis de zeolitas. Estos aspectos se estudiaron con un estudio comparativo de diferentes cationes de amonio y fosforados. Los compuestos de fósforo utilizados en este trabajo han dado lugar a nuevas estructuras cristalinas (ITQ-58 e ITQ-66) y han abierto nuevas vías de síntesis de zeolitas ya conocidas (RTH, IWV y DON), ampliando su gama de composiciones químicas. La descomposición térmica de los P-ADE confinados dentro de las zeolitas da lugar a la formación de especies de fósforo extra-red que permanecen dentro de los canales y cavidades de las zeolitas. Estas especies modulan las propiedades ácidas y de adsorción de los materiales finales dependiendo de los tratamientos post-síntesis. En este trabajo se ha estudiado una ruta para la incorporación de cantidades controladas de fósforo durante la etapa de síntesis. Esto ha permitido controlar la adsorción y las propiedades ácidas en las zeolitas de poro pequeño, lo que no se puede lograr mediante metodologías de post-síntesis.<br>[CA] Les zeolites són materials cristal·lins microporosos amb canals i mides de porus de dimensions moleculars. L'estructura i composició de les zeolites els confereix interessants propietats que permeten la seua aplicació en una àmplia gamma d'aplicacions industrials com adsorció, separació o catàlisi. La síntesi de zeolites és l'etapa més important per al control de l'estructura i composició de les zeolites i, per tant, crítica per a l'optimització de les seues propietats. Aquesta tesi s'ha centrat en la síntesi de zeolites utilitzant compostos que contenen fòsfor (cations fosfoni i aminofosfoni) com a agents directors d'estructura (P-ADE). L'ús de compostos fosforats influeix en la cristal·lització i propietats de les zeolites obtingudes en comparació amb les zeolites obtingudes amb cations d'amoni clàssics. Els compostos fosforats es van triar a causa de la seua diferent química i estabilitat pel que fa als cations d'amoni clàssics utilitzats en la síntesi de zeolites. Aquests aspectes s¿estudiaren amb un estudi comparatiu de diferents cations d'amoni i fosforats. Els compostos de fòsfor utilitzats en aquest treball han donat lloc a noves estructures cristal·lines (ITQ-58 i ITQ-66) i han obert noves vies de síntesi de zeolites ja conegudes (RTH, IWV i DO), ampliant la seua gamma de composicions químiques. La descomposició tèrmica dels P-ADE atrapats dins de les zeolites dona lloc a la for-mació d'espècies de fòsfor extra-xarxa que romanen dins dels canals i cavitats de les zeolites. Aquestes espècies modulen les propietats àcides i d'adsorció dels materials finals depenent dels tractaments post-síntesi. En aquest treball s'ha estudiat una ruta per la incorporació de quantitats controlades de fòsfor durant l'etapa de síntesi. Això ha permés controlar l'adsorció i les propietats àcides en les zeolites de porus petit, el que no es pot aconseguir mitjançant metodologies de post-síntesi.<br>[EN] Zeolites are microporous crystalline materials with channels and pore openings of molecular dimensions. The structure and composition of zeolites confers them interesting properties that allow their application in a wide range of industrial applications as adsorption, separation or catalysis. The synthesis of zeolites is the most important stage to control the structure and composition of zeolites, and thus, critical to optimize their properties. This thesis has been focused on the synthesis of zeolites using phosphorous containing compounds (phosphonium and aminophosphonium cations) as Organic Structure Directing Agents (P-OSDA). The use of these phosphorous compounds influence the crystallization and properties of the obtained zeolites compared to zeolites obtained with classical ammo-nium cations. Phosphorous compounds were chosen because of their different chemistry and stabil-ity properties respect to classical ammonium cations commonly used in the synthesis of zeo-lites. These aspects were studied in a comparative study with different ammonium and phosphorous cations. The phosphorous compounds used in this work have yielded new crystalline structures (ITQ-58 and ITQ-66) and opened new routes for the synthesis of already known zeolites (RTH, IWV and DON), widening their chemical composition range. The thermal decomposition of the P-OSDAs entrapped inside the zeolites yields to the formation of extra-framework phosphorus species that remain inside the channels and voids of the zeolites. These species modulate the adsorption and acid properties of the final materials depending on the post-synthesis treatments. In this work, a route for the incorporation of controlled amounts of phosphorus during the synthesis stage has been studied. This has allowed to control the adsorption and acid properties in small pores zeolites, which cannot be achieved by post-synthesis methodologies.<br>I wish to firstly acknowledge the Spanish Government for the necessary funding for the FPI pre-doctoral fellowship (BES-2013-062999). Also, this thesis would not have been possible without the infrastructures provided by the UPV and the CSIC staff, fused into the ITQ. Furthermore, I want to acknowledge the Microscopy Service of the UPV for their support in sample microscopy characterization<br>Simancas Coloma, J. (2021). Synthesis and Characterization of Zeolitic Materials Using Phosphorous Organic Structure Directing Agents [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/171267<br>TESIS

In this work, the crystallographic structure and its changes under thermal treatment of different systems consisting of metal oxide nanoparticles is studied. The principal method used throughout the thesis is x-ray powder diffraction enriched with grazing incidence small angle x-ray scattering when the nanoparticles form an ordered structure or with x-ray absorption spectroscopy when additional information on local crystallographic structure is required. For all the systems the preparation conditions were optimized according to the crystallographic data for further applications.

Recently, Heusler alloys are studied for their interesting magnetic and electronic properties. These properties are strongly dependent on the crystallographic struc- ture. This work deals with Heusler alloys of the A2BC type. We have powder samples and single-crystaline samples for our study as well. An object of interest was a description of crystallographic structure of the samples, site occupation numbers of each type of atoms and their possible occupation disorder. Pow- der difraction and EXAFS have been measured on the powder samples. Clasical single-crystal diffractions has been meassured on the single-crystaline samples. In the case of a modulated structure in the samples, satelite difractions have been measured too. 1

We studied epitaxial layers of Gallium Manganese Arsenide by various x-ray scattering methods. Since the positions of the Mn dopant in the a host GaAs lattice are crucial for magnetic properties of this material, we focused mainly on a development of the laboratory diffraction method capable to identify Mn in particular crystallographic positions. From the measured diffracted intensity distributed along Crystal Truncation Rods, it is possible deduce the density of Mn interstitials in two non-equivalent crystallographic positions. It is possible to decrease the interstitial Mn density by annealing. We demonstrated our method on severally annealed epitaxial layer. The depth profile of interstitial density was determined after each annealing. The annealing process was simulated by the solving of the Drift- Diffusion equations. From the comparison with the experimentally determined interstitial densities, we estimated the diffusivity of Mn interstitials in the GaAs lattice. Powered by TCPDF (www.tcpdf.org)

Title: Microstructure and properties of multiferroic complex oxide thin films prepared by pulsed laser deposition method Author: Petr Machovec Department: Department of Condensed Matter Physics Supervisor: RNDr. Milan Dopita, Ph.D., Department of Condensed Matter Physics Abstract: In the frame of this thesis, structure, microstructure, and real structure of multiferroic epitaxial layers of LuFeO3 were studied by means of X-ray reflectivity and X-ray diffraction. In theoretical part the theory of X-ray scattering on crystalline layers is described. Standard description of X-ray reflectivity on series of rough layers is presented. Moreover, a model of X-ray scattering on mosaic layer is described. For experimental part of the work three samples were prepared by pulsed laser deposition method. First sample on sapphire substrate (Al2O3), second on platinum layer deposited on sapphire substrate and third on yttrium stabilized zirconia substrate. From the X-ray reflectivity curves the parameters such as layer thickness, interface roughness, surface roughness and material density, were determined. By analysing measured reciprocal space maps, lattice parameters and mosaic model parameters, such as mean mosaic block size, mosaic block size distribution, mosaic block misorientation and residual microstrain, were...

Charles University, Faculty of Pharmacy in Hradec Králové Department of Biophysics and Physical Chemistry Author: Lucia Dulanská Supervisor: Mgr. Petra Pullmannová, Ph.D Title of thesis: Optimization of the skin barrier model with isolated ceramides of human Stratum corneum Stratum corneum (SC), the uppermost layer of the skin, regulates transcutaneous water loss and protects against outer conditions and harmful substances. It consists of cornified cells - corneocytes and extracellular lipid matrix, which is responsible for the barrier functions. Corneocytes are covered with covalently bound lipids creating the corneocyte lipid envelope (CLE). CLE is considered to interconnect the extracellular lipids with corneocytes and to have a templating effect. We aimed to optimize a skin lipid model simulating also the presence of CLE. The lipidic part of the model was prepared from an equimolar mixture of isolated human skin ceramides (hCer), cholesterol and free fatty acids (FFA, either protonated or deuterated) with 5 weight % of cholesteryl sulfate. hCer were extracted from the isolated human SC and purified by the column chromatography. The composition of hCer was determined by the high- performance thin-layer chromatography. The reverse-phase and normal phase silica gel particles served as the CLE...

The synthesis of NaxCoO2 by Pechini method (with initial sodium stoichiometry x = 1.0, 0.9, 0.8, and 0.7) was studied for the samples heat-treated in the temperature range from 550 řC to 750 řC. The structure characterization and phase composition was carried out by the powder X-ray diffraction (XRD) analysis. The elementary analysis was done using atomic absorption spectroscopy. From the thermoelectric properties, the Seebeck coefficient was measured for both α- and γ- phase. The Weiss constant was determined for α- and γ- phase by linear regression of 1/χ. The real sodium content in sodium cobaltate phase was found to be independent on initial sodium precursor weight and measurement by PXRD and Seebeck coefficient showed that the sodium content in NaxCoO2 falls in the range from x = 0.65 to 0.75. The magnetization measurements showed presence of spinel Co3O4 impurities in the samples and the analysis of magnetic susceptibility showed unusual high values of the Weiss constant for α- phase in comparison with structurally similar γ- NaxCoO2. Thin film of NaxCoO2 with initial sodium stoichiometry x = 1.0, 0.52, 0.32, and 0.175 was deposited by chemical solution deposition method using spin-coating deposition on a 00l-oriented α-Al2O3 single crystal substrate. The formation and structure characterization of...

Abstract Optimizing safety and efficiencies is vital to turbomachinery design in the aerospace industry. However, aircraft engines subject to ingestion of airborne particle mixtures of unknown size and concentration have undergone unpredictable malfunction and power losses. Premature damage could be caused by increased erosion rates from mixtures with abrasive material. Similarly, corrosion rates could also increase for mixtures with corrosive material. Further, ingestions with melting points below the combustion exit temperature do melt, adhere to turbine blades, and thereby produce clogs and power losses. Additional blockage could be caused by accumulation of material of fluctuating volumes on blades and vanes. Such malfunction can be prevented by providing these engine systems with an on-board sensor capable of defining the particle size and size distribution and determining instantaneous and cumulative ingestion rates. This study demonstrates the methods used in the design of a fiber optic sensor to size the ingested material and measure its distribution and concentration directly in an engine’s flow path. A high-velocity, high-temperature contamination rig has been designed and built for testing the sensor and evaluating its functionality under engine conditions. Durability tests will be conducted to determine sensor lifespan and assess feasibility of incorporation in current turbomachinery for aircraft protection. Contaminant particle distribution and flow patterns in pipe cross section were studied through laser diffraction and light scattering, to enhance understanding of changes in sensor upon particle impingement.

Nuclear reactor pressure vessels must be able to withstand thermal shock due to emergency cooling during a loss of coolant accident. Demonstrating structural integrity during thermal shock is difficult due to the complex interaction between thermal stress, residual stress, and stress caused by internal pressure. Finite element and analytic approaches exist to calculate the combined stress, but validation is limited. This study describes an experiment which aims to measure stress in a slice of clad reactor pressure vessel during thermal shock using time-resolved synchrotron X-ray diffraction. A test rig was designed to subject specimens to thermal shock, whilst simultaneously enabling synchrotron X-ray diffraction measurements of strain. The specimens were extracted from a block of SA508 Grade 4N reactor pressure vessel steel clad with Alloy 82 nickel-base alloy. Surface cracks were machined in the cladding. Electric heaters heat the specimens to 350°C and then the surface of the cladding is quenched in a bath of cold water, representing thermal shock. Six specimens were subjected to thermal shock on beamline I12 at Diamond Light Source, the UK’s national synchrotron X-ray facility. Time-resolved strain was measured during thermal shock at a single point close to the crack tip at a sample rate of 30 Hz. Hence, stress intensity factor vs time was calculated assuming K-controlled near-tip stress fields. This work describes the experimental method and presents some key results from a preliminary analysis of the data.

Zinc sulphide (ZnS) and zinc selenide (ZnSe) and manganese-doped and un-doped with different morphologies from 1D do 3D microflowers were successfully fabricated in only a few minutes by solvothermal reactions under microwave irradiation. In order to compare the effect of microwave heating on the properties of obtained nanocrystals, additionally the synthesis under conventional heating was conducted additionally in similar conditions. The obtained nanocrystals were systematically characterized in terms of structural and optical properties using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance UV-Vis spectroscopy (DR UV-Vis), Fourier-transform infrared spectroscopy (FT-IR), photoluminescence spectroscopy (PL), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET) surface area analysis. The photocatalytic activity of ZnSe, ZnS, ZnS:Mn and ZnSe:Mn nanocrystals with different morphologies was evaluated by the degradation of methyl orange (MO) and Rhodamine 6G (R6G), respectively. The results show that Mn doped NCs samples had higher coefficient of degradation of organic dyes under ultraviolet irradiation (UV).

Abstract A P.S.Z. coating elaborated by r.f. plasma spraying was studied and compared to industrial arc plasma-sprayed P.S.Z. coatings to evaluate the quality of the corresponding thermal barrier coating system for gas turbine applications. One commercial ZrO2 - 8% Y2O3 powder was sprayed with two industrial d.c. torches (7MB and F4) and one r.f. plasma torch (Tekna PL50). Physical properties such as density, porosity and thermal diffusivity were measured on the three types of P.S.Z. coating. The microstructure and quantitative phase analysis were respectively investigated by S.E.M. and X-Ray diffraction. The burner rig tests on the T.B.C. systems showed that the thermal shocks resistance on the r.f. coating was at least the same as the others. Induction plasma spraying gave a high deposit efficiency (around 80%) and a P.S.Z. coating with very interesting thermal properties. All these facts demonstrate that r.f plasma spraying can be a competitive process to produce high quality thermal barrier coatings.

A time domain maneuvering simulation of an IACC class yacht suitable for the analysis of unsteady upwind sailing and tacking is presented. The simulation code (RODAN) considers motions in six degrees of freedom. The hydrodynamic and aerodynamic loads are calculated primarily with unsteady potential theory supplemented by empirical models. The hydrodynamic model includes the effects of incident waves. Control of the rudder is provided by a simple feedback autopilot which is tuned to mimic human steering. The hydrodynamic models are based on the superposition of force components. The components fall into two groups, those which the yacht will experience in calm water, and those due to incident waves. The calm water loads include double body maneuvering loads hydrostatic loads, free surface radiation loads, and viscous/residual loads. Incident wave components include Froude-Krylov and diffraction loads. The double body maneuvering loads are calculated with an unsteady panel code which treats the instantaneous geometry of the yacht below the undisturbed free surface. The Groude-Krylov pressures are integrated over the surface defined by the panel code. The free surface radiation loads are calculated via convolution of impulse response functions derived from seakeeping strip theory. The diffraction loads are also derived from strip theory. The viscous are residual loads are based upon empirical estimates. The aerodynamic models are based on a database of steady state sail coefficients. Dynamic effects are modeled by using the instantaneous incident wind velocity and direction as the independent variables for the sail load contribution of each of several chordwise strips. The sail coefficient database was calculated numerically with potential methods and simple empirical viscous corrections. Additional aerodynamic load calculations are made to determine the parasitic drag of the rig and hull.

Small gas turbine engines, especially if they are used as automotive propulsion systems, are often compared to diesel engines with regard to their specific fuel consumption. Aside from high gas temperatures and the use of very efficient heat exchangers, there has to be a form of thermal insulation of the turbine casing which can be achieved by means of a thick Thermal Barrier Coating (TBC). Theoretical considerations about the necessary morphology are made on the calculated stress situation within the coating. It will be described, how the TBC morphology can be influenced as desired, by means of a specific selection of spray parameters. In addition, the correlation between spray parameters and the phase distribution, as obtained from neutron diffraction analyses, will be reported. The compatibility between theory and practice will be proven by means of a turbine case dummy with an inner TBC with a thickness of 5 mm which was tested very realistically in a specially designed flame rig. Microsections of this coating are used to confirm the theoretical considerations of the necessary morphology.

Abstract The preheating of metallic substrates before powder deposition in air plasma spraying improves the adhesion of oxide coatings, provided heating is performed with an optimal procedure to avoid a too high oxidation state of the surface. It means that the temperature level and heating time have to be monitored carefully. In these conditions a thin layer (&amp;lt;100 nm) of oxides is formed on the substrate surface, the resulting contact of the molten droplets impinging the hot substrate is excellent (Rth&amp;lt;10-7 m2.K/W) and the adhesion properties of coatings are enhanced. This paper is devoted to the study of the metallic surface. The substrate heating and thus oxidation are obtained with a d.c. Ar-H2 plasma jet flowing in air of which the stand off distance is maintained at 100 mm. The parameters investigated are macroscopic surface temperature and heating time. The characterization of the oxide layers is achieved by Mossbauer spectroscopy, near grazing X-ray diffraction, near UV-Visible-near IR spectroscopy and specular reflection infrared spectroscopy. At the end of this paper an attempt will be made to correlate these characterizations to the splats microstructure and coatings adhesion.

During demobilization of jack-up rigs, when the rig’s legs are stuck in the seabed due to resistance from the surrounding soil, the hull is lowered more than the neutrally buoyant condition to draw the legs up. This operation of pulling down the hull to provide net upward buoyancy force to extricate the legs is called ‘pull-down’ operation. The hull, being partly underwater, attracts considerable wave forces even during relatively calm weather. Due to the changing support condition at bottom of the leg, while it is being extricated, the natural period of the system changes continuously. The dynamic amplification may be high when the wave periods are close to the natural periods of the structure. This makes it imperative to consider dynamic analyses of the rig. A unique but simplified ‘pull-down’ analysis procedure is developed in this study considering the harmonic wave forces, added mass of the hull in water, boundary condition of the legs in soil, and distributed buoyancy springs under the hull. Wave excitation loads and added mass for the hull are computed using diffraction-radiation analysis of the hull in water. A number of steady state dynamic analyses of the complete jack-up rig structural model have been performed for a range of wave periods, water depths, and drafts of the hull. Three different bottom boundary condition scenarios have been considered — three legs supported, one leg free but two legs still stuck in soil, and two legs free but one leg still stuck. The static and the dynamic load cases are combined to get the maximum effects on the stresses of the leg members. Using this procedure the allowable safe wave heights are predicted for a range of wave periods for a particular water depth, and draft of the hull. Results are presented for one class of jack up rig. The results show that the leg stresses are strongly dependent on the wave periods, indicating the importance of including dynamic effects in the pull-down analysis.