Submitted by Rafael Santana (rafael.silvasantana@ufpe.br) on 2017-07-10T19:30:23Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Dissertacao - Pedro Negrão.pdf: 2417925 bytes, checksum: 563fc37dbb3bf794487bc4e3c8fc102a (MD5) / Made available in DSpace on 2017-07-10T19:30:23Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Dissertacao - Pedro Negrão.pdf: 2417925 bytes, checksum: 563fc37dbb3bf794487bc4e3c8fc102a (MD5) Previous issue date: 2016-03-29 / CAPES / As argilas compõem um grupo de matérias-primas muito importante devido a suas múltiplas funções industriais. Em especial o caulim, possui propriedades físicas e químicas que possibilitam a sua utilização no processo industrial de uma grande gama de produtos, desde matéria-prima para a indústria cerâmica, de carga e cobertura de papel, entre outras. Esta pesquisa objetivou descrever, através da caracterização mineralógica, análise química, análise granulométrica, ensaios tecnológicos e de plasticidade, as características do material arenocaulinítico sondado no município de Igarassu – PE, ocorrência localizada próxima ao bairro de Nova Cruz 2. O material foi coletado através de sondagem a trado, tendo as amostras passado por análise mineralógica por difração de raios X, análise química por fluorescência de raios X, análise granulométrica, ensaios de plasticidade e foram confeccionados corpos de prova para a realização de ensaios tecnológicos. Os resultados obtidos foram comparados com as características de caulins de outros jazimentos descritos na literatura e com as especificações dos caulins aproveitados industrialmente. / Clays form a group of so important raw materials due to its multiple industrial functions. In particular, the kaolin has physical and chemical properties which allow its use at the industrial process a wide range of products from a raw material for ceramic industry, filler and paper coating, among others. This research aimed to describe through mineralogical characterization, chemical analysis, particle size analysis, technological tests and plasticity characteristics of sandy-kaolinitic materials collected in the city of Igarassu - PE, occurrence located near the Nova Cruz 2. The material was got by auger boring, the samples submitted to a mineralogical analysis through X ray diffraction, chemical analysis through X ray fluorescence, particle size analysis, plasticity tests and was prepared specimens to be performed for the technological tests. The results obtained were compared with the characteristics of kaolin of other deposits described in the literature and with the specifications of kaolin exploited industrially.

abstract: The mineralogy of the deep mantle is one of the key factors for the chemical evolution of the Earth. The constituent minerals of the mantle rock control the physical properties of the mantle, which have significant impacts on the large-scale processes occurring in the Earth's interior. In my PhD research, I adopted experimental approaches to investigate the mineralogy and the physical properties of the Earth's materials in the deep mantle by using the diamond anvil cells (DACs) combined with in-situ X-ray diffraction techniques. First, I found that Ca-bearing bridgmanite can be stable in the deeper part of the Earth's lower mantle where temperature is sufficiently high. The dissolution of calcium into bridgmanite can change the physical properties of the mantle, such as compressibility and viscosity. This study suggests a new mineralogical model for the lower mantle, which is composed of the two layers depending on whether calcium dissolves in bridgmanite or forms CaSiO3 perovskite as a separate phase. Second, I investigated the mineralogy and density of the subducting materials in the Archean at the P-T conditions near 670 km-depth. The experiments suggest that the major phases of Archean volcanic crust is majoritic garnet and ringwoodite in the P-T conditions of the deep transition zone, which become bridgmanite with increasing pressure. The density model showed that Archean volcanic crust would have been denser than the surrounding mantle, promoting sinking into the lower mantle regardless of the style of the transportation in the Archean. Lastly, I further investigated the mineralogies and densities of the ancient volcanic crusts for the Archean and Proterozoic at the P-T conditions of the lower mantle. The experiments suggest that the mineralogy of the ancient volcanic crusts is composed mostly of bridgmanite, which is systemically denser than the surrounding lower mantle. This implies that the ancient volcanic crusts would have accumulated at the base of the mantle because of their large density and thickness. Therefore, the distinctive chemistry of the ancient volcanic crusts from the surrounding mantle would have given a rise to the chemical heterogeneities in the region for billions of years. / Dissertation/Thesis / Doctoral Dissertation Geological Sciences 2020

Este trabalho consiste em uma introdução teórica dos fundamentos básicos da difração de raios-X por cristais, de uma descrição sucinta do difratômetro automático CAD-4 da Enraf-Nonius, e do método de Patterson e dos métodos diretos usados na determinação de estruturas. Foram resolvidas as estruturas cristalinas e moleculares de um complexo de níquel (II) e de cinco triterpenos. Os cinco triterpenos são produtos naturais extraídos da casca de madeira Austroplenckia populnea (Celastraceae). Monocristais desses produtos foram analisados por difração de raios X usando um difratômetro automático CAD-4 e com radiação de M&#959K&#945 (&#955= 0,71073&#197) monocromatizada por cristal de grafita. Os principais dados cristalográficos estão resumidos na tabela abaixo:   triterpenos T1 T2 T3 T4 T5 Fórmula Química C31H48O4 C30H48O3 C31H48O3 C31H50O3 C30H48O4 Mr 484,73 456,71 468,73 470,74 472,71 Grupo Espacial P21 P1 C2 P212121 P21 a(Å) 6,697(2) 7,271(2) 12,109(2) 6,815(2) 14,695(2) b(Å) 14,714(7) 12,389(8) 7,346(2) 16,127(2) 13,699(2) c(Å) 13,866(3) 15,632(2) 30,570(6) 24,695(4) 6,622(3) α(°) 90 74,95(2) 90 90 90 β(°) 103,53(2) 87,55(2) 99,83(2) 90 104,45(2) γ(°) 90 86,76(4) 90 90 90 Z 2 2 4 4 2 V(Å3) 1328(1) 1357(1) 2679(2) 2714(2) 1288(1) dc(g⋅cm-3) 1,211 1,118 1,162 1,152 1,219 μ(cm-1) 0,726 0,651 0,675 0,668 0,733 F(000) 532 504 1032 1040 520 R 0,0485 0,0996 0,0574 0,0545 0,0420 Nº refl.: I>3σ(I) 1395 1972 751 1438 838 O complexo de níquel, [NiII(DPEH)2](NO3)2 2H2O, foi sintetizado [70] a partir de uma solução alcoólica de 2 moles do ligante DPEH (Diacetilmonooxima - &#946 - Piridil-(2)-Etilimina) para cada mol de [Ni(OH2)6](NO3)2. Um monocristal desse composto foi analisado por difração de raios X, usando um difratômetro automático CAD-4 e radiação de M&#959K&#945 (&#955 = 0,71073&#197) monocromatizada por cristal de grafita. Dados cristalográficos principais: sistema monoclínico Cc, Mr = 629,27, a = 8,502(2), b = 18.702(2), c = 18.653(4)&#197, &#946 = 103,22(2)&#176, V = 2887(2)&#1973, Z = 4, dc = 1,448gcm-3, &#956 = 7,36cm-1, F(000) = 1312, R =0,0594 e 1656 refleções com I &#62 2&#959(I). O átomo de Ni está coordenado por seis átomos de N com uma configuração octaédrica distorcida. / This work consist of a theoretical introduction of the basic principles of x-ray diffraction by crystals, a brief descruption of the automatic diffractometer CAD-4 Enraf-Nonius and the Patterson and direct methods used in structure determination. The crystals structures of one Ni(II) complex and Five triterpenes were solved. The five triterpenes are natural products extracted from the bark of Austroplenckia populnea (Celastraceae). Single crystals of the products were analyzed by X-ray diffraction, using the CAD-4 automatic diffractometer M&#959K&#945 (&#955= 0,71073&#197) monochromatizated by a graphite crystal. The relevant crystallographic data are summarized in the table below:   triterpenos T1 T2 T3 T4 T5 Fórmula Química C31H48O4 C30H48O3 C31H48O3 C31H50O3 C30H48O4 Mr 484,73 456,71 468,73 470,74 472,71 Grupo Espacial P21 P1 C2 P212121 P21 a(Å) 6,697(2) 7,271(2) 12,109(2) 6,815(2) 14,695(2) b(Å) 14,714(7) 12,389(8) 7,346(2) 16,127(2) 13,699(2) c(Å) 13,866(3) 15,632(2) 30,570(6) 24,695(4) 6,622(3) α(°) 90 74,95(2) 90 90 90 β(°) 103,53(2) 87,55(2) 99,83(2) 90 104,45(2) γ(°) 90 86,76(4) 90 90 90 Z 2 2 4 4 2 V(Å3) 1328(1) 1357(1) 2679(2) 2714(2) 1288(1) dc(g⋅cm-3) 1,211 1,118 1,162 1,152 1,219 μ(cm-1) 0,726 0,651 0,675 0,668 0,733 F(000) 532 504 1032 1040 520 R 0,0485 0,0996 0,0574 0,0545 0,0420 Nº refl.: I>3σ(I) 1395 1972 751 1438 838 The Ni complex, [NiII(DPEH)2](NO3)2 2H2O, was synthesized from a 2M alcoholic solution of the ligand DPEH (Diacethylmonoxima - &#946 - Pyridil-(2)-Ethylimina) for each mol of [Ni(OH2)6](NO3)2. A single crystal of this compound was analyzed by X-ray diffraction, using the CAD-4 automatic diffractometer M&#959K&#945 (&#955 = 0,71073&#197) monochromatizated by a graphite crystal. Principal crystallographic data are: monoclinic Cc, Mr = 629,27, a = 8,502(2), b = 18.702(2), c = 18.653(4)&#197, &#946 = 103,22(2)&#176, V = 2887(2)&#1973, Z = 4, dc = 1,448gcm-3, &#956 = 7,36cm-1, F(000) = 1312, R =0,0594 and 1656 reflections with I &#62 2&#959(I). The Ni atom is coordinated to six N atoms in a distorted octahedrical configuration.

Les puits quantiques InGaN/GaN montrent la plus grande efficacité connue dans le bleu-UV et le défi actuel dans ce type de matériau est de pousser leur émission vers les grandes longueurs d’ondes. Ceci serait possible en augmentant la composition en indium, mais il faut alors gérer les contraintes résultantes. Ce travail a mis en œuvre la microscopie électronique en transmission et la diffraction des rayons X pour déterminer la composition chimique à l’intérieur des couches InGaN, le taux de relaxation et le type de défauts présents. Les résultats montrent qu’il n’y a pas de fluctuations de composition en indium dans les couches d’InGaN étudiées avec des taux d’indium de l’ordre de 20%. Ainsi, la différence d’émission des échantillons pourrait s’expliquer par la variation d’épaisseur des puits quantiques InGaN et laprésence de défauts. En effet, plusieurs types de défauts ont été observés et caractérisés tels que les pinholes ou des domaines de défauts plans selon leur origine. Dans les multicouches InGaN/GaN avec couches AlGaN compensatrices de contrainte,la diffraction des rayons X a montré que lorsque l’épaisseur des couches d’AlGaN augmente en gardant constante l’épaisseur entre les couches actives d’InGaN (avec une valeur d’environ 16-17 nm), les puits quantiques sont totalement contraints dans le plan de croissance et en dehors. Par microscopie électronique, nous montrons queleur relaxation se fait par formation aussi bien de défauts en domaines plans que de dislocation de type a. Ces dislocations se propagent des pits quantiques vers la surface, et la densité des défauts augmente avec l’épaisseur des couches d’AlGaN. / InGaN/GaN quantum wells show the highest known emission efficiency in UV-blue and the current challenge is to push to longer wavelengths. This would be possible by increasing the indium composition but the challenge becomes how to handle the resulting strains. This work has combined transmission electron microscopy and Xray diffraction in order to determine the relaxation rates, the local chemical composition and defects formation in these systems. The results show that there are no composition fluctuations in these InGaN layers where the indium content was around 20%. Therefore, the differences in emission may be explained by the changes in quantum wells thicknesses and/or the presence of defects. Indeed, several types of defects have been observed and characterized, such as pinholes or planar defect domains. For InGaN/GaN quantum wells with strain compensating AlGaN layers, Xray diffraction showed that, when the AlGaN layer thickness increases, keeping constant the spacing between InGaN layers (around 16-17 nm), the quantum wellsare totally strained in and out the growth plan. Using transmission electron microscopy, it is shown that the relaxation occurs through the formation of domains as well as a type dislocations. The dislocations propagate from the quantum well tothe surface and the density of the defects increases with the thickness of the AlGaN layers.

In der vorliegenden Arbeit wurden Röntgentechniken benutzt um die Struktur von dünnen (etwa 40 nm) CrSi2-Schichten, die unter UHV-Bedingungen mittels reaktive Koabscheidung und template-Verfahren auf Si(001) hergestellt wurden, zu charakterisieren. Die Ergebnisse wurden mit TEM-, SEM- und RBS-Untersuchungen korreliert und ergänzt. Die XRD-Analysen zeigen, dass die beiden Abscheideverfahren immer zur Bildung der CrSi2-Phase führen, wobei die Kristallite mit einer bevorzugten Orientierungsbeziehung CrSi2(001)[100] || Si(001)[110] wachsen. Im ersten Teil der Arbeit wurde die Cr-Si-Koabscheidung benutzt um die Prozessparameter zu bestimmen, die zum Wachstum epitaktischer Schichten führen können. Die Strukturuntersuchungen zeigen, dass nur bei einer Substrattemperatur von 700°C nahezu geschlossene Schichten mit Kristalliten, welche lateral eine Größe bis zu 300 nm haben und neben der bevorzugten noch andere Orientierungen zum Substrat aufweisen, entstehen. Als zweite Herstellungsmethode wurde das template-Verfahren verwendet, wo die Cr-Si-Koabscheidung auf ein vorher in-situ präpariertes ultradünnes CrSi2-template erfolgt. Die Morphologie und die Stärke der bevorzugten Orientierung der CrSi2-Schichten sind stark von der template-Dicke abhängig. Die Abscheidung auf CrSi2-templates, welche aus einer Cr-Schicht mit nominaler Dicker von 0,35 nm bis 0,52 nm entstehen, führt zum Wachstum weitgehend geschlossener, homogener und epitaktischer CrSi2-Schichten. Ein Modell, das den Einfluss der template-Dicke auf die Qualität der CrSi2-Schichten erklären kann, wird vorgeschlagen.

Title: Study of new type of Ti-NT nanotubes that can be used as a filler in polymer matrix Author: Tereza Brunátová Department: Department of Condensed Matter Physics Supervisor: doc. RNDr. Radomír Kužel, CSc. Abstract: The subject of presented work has been devoted to a structure of titanate nanotubes which were prepared by hydrothermal treatment of TiO2 powder in NaOH solution. Structure determination was done mainly with two complementary methods - X-ray diffraction and transmision elec- tron microscopy. A influence of structure by changing particle size and crystal structure of the initial powder TiO2 was studied as well. Three different mod- els of nanotube structure were build. These models were used for a calculation of powder X-ray diffraction pattern and they were compared to experiment pattern. Keywords: titanates nanotubes, computer simulations of powder X-ray diffrac- tion patterns, X-ray diffracion, electron microscopy

Masters of Science / Rare-earth (RE) compounds have been an attractive subject, based on the unique electronic structures of the rare-earth elements. In particular, the RETX (RE = rare-earth, T = 3d/4d/5d, transition metals, and X = p – block elements) series is a large family of intermetallic compounds which crystallizes in different crystal structure depending on the constituents. Most of these compounds crystalize in the hexagonal, orthorhombic, and tetragonal crystal structure. On the other hand, the family of compounds RET2X2 adopted the tetragonal crystal structure of the ThCr2Si2 or the CaBe2Be2 with different space groups. Owing to the different crystal structure, these compounds show versatile magnetic and electrical properties such as Kondo effect, complex magnetic behaviour, valence fluctuation, unconventional and conventional superconductivity, heavy fermion behaviour, Fermi and non – Fermi liquid behaviour, metamagnetism, spin – glass, memory effect, crystal electric field (CEF), magnetoresistance and magnetocaloric effect. The history of magnetism reveals that it is closely related to practical applications and magnetic materials from the most vital components in many applications. These are memory devices, permanent magnets, transformer cores, magneto-mechanical devices and magneto-electronic devices. Recent additions to this list include magnetic refrigeration through the studies of magnetocaloric effect as well as spintronics. Magnetic refrigeration (MR) is an emerging technology and shows real potential to enter conventional markets and the principles of MR obeys the magnetocaloric effect (MCE), which is based on the effect caused by a magnetic field on the materials that accept the property of varying the magnetic entropy, as well as its temperature when varying the magnetic field. In this thesis, we report giant magnetocaloric effect and magnetic properties of NdPd2Al2 and RECuGa (RE = Nd, Dy, and Ho) compounds. These investigations were done through measurements of X – ray diffraction (XRD), magnetic susceptibility, ((T)), magnetization, (M(H)), isothermal magnetization, (M(H, T)), heat capacity, (Cp(T)) and electrical resistivity, ((T)). MCE has been studied from the isothermal magnetization and heat capacity measurements.The first chapter of the thesis describes the theoretical background from which the experimental results have been analyzed and interpreted. This is followed by the chapter which presents experimental details and methodology carried out in this thesis. Chapter three presents the results and discussion of the transport, magnetic and magnetocaloric properties of NdPd2Al2 compounds. XRD studies confirm the tetragonal CaBe2Ge2 – type structure with space group P4/nmm (No. 129). The results of (T), (T) and Cp(T) indicate a putative antiferromagnetic (AFM) phase transition at low temperature at, TN = 3 K. On the other hand, (T) data at high temperatures follow the Curie – Weiss relationship giving an effective magnetic moment close to that expected for the trivalent Nd3+ ion. The magnetization results indicate metamagnetic – like transition at a low field that bears a first-order character which corroborates with the Below – Arrott plots. Giant MCE was obtained for the NdPd2Al2 compound similar to those reported for potential magnetic refrigerant materials. Chapter four discusses the magnetic and thermodynamic properties of the series of compounds RECuGa where RE = Nd, Dy, and Ho. XRD studies indicate the orthorhombic CeCu2 – type crystal structure with space group Imma (No. 74) for all three compounds. Magnetic measurements indicate a putative AFM phase transition below 𝑇𝑁 = 7.1, 8.5, and 3.7 K for Nd, Dy, and Ho compounds, respectively. The high-temperature (T) data for all three compounds follow the Curie – Weiss relationship giving an effective magnetic moment close to that expected for the trivalent rare-earth ion. Again, large MCE were obtained for all three compounds similar to those reported for materials that can be used as magnetic refrigerant materials.

Bi-annual report on the activities at the ROssendorf BeamLine (ROBL) at the ESRF in Grenoble. The report contains selected contributions on actual research topics, a list of all scheduled experiments, and short experimental reports.

The paper describes the Rossendorf Beamline (ROBL) built by the Forschungszentrum Rossendorf at the ESRF. ROBL comprises two different and independently operating experimental stations: a radiochemistry laboratory for X-ray absorption spectroscopy of non-sealed radioactive samples and a general purpose materials research station for X-ray diffraction and reflectometry mainly of thin films and interfaces modified by ion beam techniques. The radiochemistry set-up is worldwide an unique installation at a modern synchrotron radiation source.

A dimensionality controlled metal insulator transition in epitaxial [LaNiO3 (d nm)/LaAlO3(2nm)]10 (100) superlattices (thereafter [d/2]10 SLs) is demonstrated for decreasing LaNiO3 single layer thickness from 4nm down to 1.2 nm. The [4/2]10 SL shows metallic behavior with positive resistivity temperature coefficient, while the [2/2]10 SL shows a metal-insulator transition with crossover from 3D to two-dimensional single-layer dimensionality. Strong localization appears for the [1.2/2]10 SL with the resistivity being dominated by two-dimensional variable range hopping with a localization length of about 0.035 nm.