Diploma thesis deals with laboratory preparation of the main clinker mineral - alit. The theoretical part summarizes the existing knowledge and the practical part deals with the methodology of preparation of the alite. The main goal was to prepare and study the monoclinic phases of alite, another goal was to optimize the triclinic alite.

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 master’s thesis is focused on the effect of mixing water pH value on hydration and mechanical properties of cement composites based on portland cement. Source material was CEM I 42,5 R. Hydration process was analyzed by isoperibolic calorimetry, X-ray diffraction analysis and differential thermal analysis. Compressive and flexural strength was examined as mechanical properties. The samples microstructure was observed by scanning electron microscopy. Influence of mixing water pH value on flexural and compressive strength, retardation of hydration and ratio of individual phases was shown.

Thin films become more and more important in science and industry. The main objective of this work was the expanding of the measurement capabilities of the XRD 3000PTS to the field of thin films. The success of the changes was documented by maesurements on TiC thin films. / Dünne Schichten gewinnen in Forschung und Industrie zunehmend an Bedeutung. Ziel der Arbeit war es deshalb, den Einsatzbereich des vorhandenen Diffraktometers XRD 3000PTS auf Untersuchungen an dünnen Schichten zu erweitern. Der Erfolg der Veränderungen konnte mit Messungen an einer TiC Probenserie bestätigt werden.

Title: Preparation and characterization of substituted Y ferrites in the form of ceramics and thin films Author: Dorota Pulmannová Department: Department of Inorganic Chemistry, Faculty of Science, Charles University in Prague Supervisor: RNDr. Daniel Nižňanský, Ph.D. Consultant: Ing. Josef Buršík, CSc. Abstract: In this work we describe a preparation and characterization of a hexagonal ferrite series with composition BaSrCoZnXFe11O22 where X=Fe, Al, Ga, In and Sc. We have prepared these ferrites in the powder and ceramic form using the citrate synthesis and in the thin film form using the chemical solution deposition method. Using the powder neutron diffraction we have found that the sample containing only Fe has collinear magnetic structure that belongs to the C2/m or C2'/m' group. Magnetic structure of the samples substituted with In and Sc is similar, but the magnetic moments of the 18hVI site atoms are not aligned parallely with the other moments. Magnetic structure of Ga-substituted sample is different, it is modulated with a propagation vector k ≈ (0, 0, 3/4). Propagation vector of the Al-substituted ferrite is k ≈ (0, 0, 3/2). Substituting elements show strong preferences for the cation sites. Al and Ga prefer the 3bVI site, Zn prefers the tetrahedral 6cIV and In and Sc prefer the 6cVI site. Room...

>Magister Scientiae - MSc / Organic-inorganic lead-based perovskite has exhibited great performance in the past few years. However, the lead (Pb) embedded in those compounds is a significant drawback to further progress, due to its environmental toxicity. As an alternative, tin (Sn) based-perovskites have demonstrated promising results in terms of electrical and optical properties for photovoltaic devices, but the oxidation of tin ion- from stannous ion (Sn2+) to stannic ion (Sn4+) presents a problem in terms of performance and stability when exposed to ambient conditions. A more feasible approach may be in a Pb-Sn binary metal perovskite in pursuit of efficient, stable perovskite solar cells (PSCs) with reduced Pb-content, as compared to pure Pb- or Sn-based PSCs. Here, we report on the deposition of a Pb-Sn binary perovskite by sequential chemical vapor deposition.

This work addresses the growth of ultrathin magnetite (Fe3O4) and cobalt ferrite (CoFe2O4) films and their thorough structural, electronic, and magnetic characterization. In a first step, ultrathin Fe3O4 films are grown on SrTiO3(001) substrates by reactive molecular beam epitaxy (RMBE) and the substrate-induced anomalous strain behavior of the films is investigated by complementary high-resolution transmission electron microscopy (HRTEM) and (grazing incidence) X-ray diffraction [(GI)XRD] measurements. Next, an additional CoO film is deposited on similar Fe3O4/SrTiO3(001) heterostructures to demonstrate an alternative route for the synthesis of cobalt ferrite films through the thermally mediated interdiffusion of both oxide films. The evolution from the initial bilayer stacks to completely reacted cobalt ferrite films is extensively monitored by soft and hard X-ray photoelectron spectroscopy (soft XPS and HAXPES) and (GI)XRD. Complete intermixing and formation of single cobalt ferrite films is confirmed by angular-resolved HAXPES (AR-HAXPES) and X-ray reflectivity (XRR). The study of the cationic distribution resulting from this novel synthesis technique and its effects on the magnetic properties of the cobalt ferrite films is the subject of the subsequent part. Here, X-ray magnetic circular dichroism (XMCD) and superconducting quantum interference device (SQUID) magnetometry serve as key investigation techniques, which are further complemented by AR-HAXPES and atomic force microscopy (AFM) measurements. In a final step, highly crystalline cobalt ferrite films with different cationic stoichiometries are grown on MgO substrates using RMBE while their growth behavior is captured in real-time using operando XRD. Further structural characterization of the films is carried out by low-energy electron diffraction and XRR, whereas HAXPES and SQUID provide fundamental information on the electronic, chemical, and magnetic properties of the films.

This project was ordered by Sandvik Materials Technology and was performed by a group of students at Uppsala university. The purpose of the project was to study precipitation behavior and structure stability in six advanced heat resistant alloys. Each sample were subjected to a creep rupture test in 600 or 700°C depending on the alloy type. Two parts of each alloy where examined; one part which had been affected by creep and another part which was unaffected by creep. A literature study was performed first to gain knowledge of the scientific theory utilized in this project, namely creep, precipitation hardening, and about the different materials which were analyzed. Preliminary results for the phase composition of the materials were obtained from a Thermo-Calc (TC) simulation. The SEM-images showed nothing noteworthy for any sample due to the roughness of the sample surfaces. The EDS-analysis showed chromium depletion in the centers of the aged samples of HT9 and Sanicro® 75X. Other minority phases such as Cr23C6 in Sanicro®70, P-phase and a titanium nitride phase in sanicro® 60X, VB in Esshete 1250 and Sigma-phase in 4C54 were identified using EDSmapping. It was found that when using XRD to analyze the phase compositions of small samples it is impractical to have the samples cast in bakelite beforehand. The XRD-results obtained in this project showed that more than 90% of the XRD diffractogram for every sample was graphite, which made the identification of minority phases impossible. The quality of the LOM-images varied greatly between samples, for 4C54 grain sizes were measured in all images, for Esshete 1250 grain sizes were measured for the crept sample, and for Sanicro® 60X measurements could only be taken from one image. Most of the sample preparation was insufficient to achieve the test results necessary for complete microstructural analysis and phase analysis of the samples. The mistakes in the practical steps of the project were noted and improvements for these mistakes are presented in the conclusion.

京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第21879号 / エネ博第380号 / 新制||エネ||74(附属図書館) / 京都大学大学院エネルギー科学研究科エネルギー基礎科学専攻 / (主査)准教授 高井 茂臣, 教授 萩原 理加, 教授 佐川 尚 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DFAM

Every investigation technique has its specific advantages: this is the reason why, in modern research, it is common to combine many investigation techniques – especially the non-destructive ones - to achieve deeper structural information about a sample. X-ray diffraction (XRD) and fluorescence (XRF) techniques are useful non-destructive analytical techniques, with applications not only in industrial field and mining but also in environmental control and cultural heritage monitoring and conservation. In the present research, the advantages of a combined approach with XRF and XRD techniques are considered, due to their complementarity, and a new method of combining data is presented, executing the simultaneous computation of the refinement both for XRF and XRD. In this case, instead of the common approach with an iterative refinement, passing from XRF to XRD and vice versa, both XRF and XRD data are processed simultaneously with a combined Rietveld refinement. This innovative approach has been implemented in the program MAUD, combining original XRD algorithm with the XRF module implementation from the GimPy and JGIXA programs, creating comprehensive radiation–matter interaction model, which takes care of both elastic scattering and photoelectric absorption/fluorescence. Moreover, through a plugin-based application container, Eagle-X, specifically developed for this research project, some easy external wizards have been developed using JAVA language for preliminary XRF analysis and model set-up, which will be in the next future integrated into the MAUD current interface. This new approach has been applied to two case studies. The first study was in the cultural heritage field with the analysis of ancient Venetian coins, called sesini, which were never investigated before. These coins were widely used in the Venetian Republic over a time span ranging from the second half of the 16th until the early years of the 17th century. The rationale of the study was to establish a multilayer model that once validated could be used for fully non-destructive characterization of similar items. The approach, applied to 20 samples from different time periods, has given interesting results. First, the actual composition of the copper-based alloy used for these specific types of Venetian coin has been measured for the first time, using a three-layer model, with also direct measurements on the coin cross-section for validating the data obtained. Second, the detailed characterization of the coins provided essential background knowledge for fully non-destructive characterization of the same kind of coins. Third, the data obtained were very interesting from a historical point of view, because the silver depletion, which this research has investigated over the coin series, reflects a political and economic situation in strong evolution for the Venetian Republic in the second half of 16th century. Political and economic competitors and a continuous effort in military confrontations obliged Venice to revise its coin system and values not only for sesini but also for the other silver-based coins, with larger value, in a process called debasement. The second application of the combined approach regarded an industrial application concerning a sintered titanium alloy, Ti6AlV4, that has the widest use (about 45% of the total production), because of good machinability and excellent mechanical properties. This is an alloy which contains the two allotropic forms of Ti, the Ti-alpha, which has compact hexagonal cell, stable at room temperature, and Ti-beta phase, which has a body-centred cubic lattice, stable over 882°C. The presence of the two phases is related to the presence of atomic elements which are alpha- and beta-stabilizers. In this case study six samples, produced with Selective Laser Melting (SLM) technology, with different production parameters, has been considered, and a model based on a surface layer of compact oxide and a bulk with the alloy only has been adopted. The model has evidenced the presence of the TiO2 oxide on the surface, as attended from existing literature, and confirmed the quality of the alloy because for all the samples, the investigated areas report Al e V content inside the ranges required by ASTM and ISO specifications. The analysis has allowed also to investigate the presence of contaminants like copper due to the cutting process by Electrical Discharge Machining (EDM), and to find a correlation between the content of Ti-beta phase inside the samples and the combined presence of iron and silicon, which increases as soon as increase also the two elements. Moreover, the increase of Ti-beta phase is boosted by the contemporary increase in energy density during SLM production process. This is consistent with the fact that higher energy allows a higher localized temperature in SLM process and the equilibrium fraction of beta phase rises at high temperatures. This then leads to a higher fraction of alpha+beta phases at room temperature and, because the cooling rate was the same for all samples, this means a higher fraction of  phase at room temperature. The application of the technique to the two case studies is very productive from the informational point of view, but a critical aspect for a successful application of the technique is the sample. No preparation is virtually needed for analysis but, of course, this is immediately true for industrial components as soon as they are produced, but it is not so true for archaeological artefacts, where the condition of production, history and store conditions are unknown. Corrosion patinas can alter the read of the data, and some care must be taken for analysis, not only because the patinas may not be homogenous, but also because the depth of penetration for XRF and XRD are not the same, respect to the same substrate. The cleaning of the artefacts is not always possible or desired by the owners, so this can at first stage complicate the approach to combined analysis, regarding the model to be adopted in material simulation for data interpretation. In any case, the combined analysis remains a valid approach provided that the user is conscious of the limits in terms of depth of analysis, linked to the analysis tool (X-ray beam, detector, etc...) and to the surface conditions of the sample.