Hydrous lithium aluminosilicate (L–A–S–H) and lithium aluminate (L–A–H) gels are candidate precursors for glass-ceramics and ceramics with potential advantages over conventional processing routes. However, their structure before calcination remained largely unknown, despite the importance of precursor structure on the properties of the resulting materials. In the present study, it is demonstrated that L–A–S–H and L–A–H gels with Li/Al ≤ 1 can be produced via an organic steric entrapment route, while higher Li/Al ratios lead to crystallization of gibbsite or nordstrandite. The composition and the structure of the gels was studied by thermogravimetric analysis, X-ray diffraction, 27Al and 29Si magic-angle spinning nuclear magnetic resonance, and Raman spectroscopy. Aluminium was found to be almost exclusively in six-fold coordination in both the L–A–H and the L–A–S–H gels. Silicon in the L–A–S–H gels was mainly in Q4 sites and to a lesser extent in Q3 sites (four-fold coordination with no Si–O–Al bonds). The results thus indicate that silica-rich and aluminium-rich domains formed in these gels.

Trois systèmes ternaires (SAS, BAS et ZAS) ont été étudiés dans le cadre de la thèse. Les principaux objectifs étaient l’élaboration et la caractérisation de verres aluminosilicatés de Sr, Ba et Zn peu étudiés auparavant. Une étude systématique a été réalisée sur des aluminosilicates vitreux et dans certains cas sur des aluminosilicates fondus avec différents rapports MO/Al₂O₃ (M = Sr, Ba, Zn) et SiO₂/Al₂O₃. Les compositions étudiées couvrent une partie significative des diagrammes ternaires (des silicates aux verres peralumineux, des compositions pauvres en silice à celles riches en silice). Cela a permis d'accroître nos connaissances sur les domaines de vitrification de ces systèmes. Afin d’obtenir des informations sur la structure et les propriétés macroscopiques des verres SAS, BAS et ZAS, une approche multi-technique a été mise en place. Une telle approche permet d’avoir une vue d’ensemble sur les systèmes étudiés et de trouver des origines nano- à microscopiques aux propriétés macroscopiques. La spectroscopie de résonance magnétique nucléaire, la diffractométrie de neutrons et la spectroscopie Raman ont été utilisées au cours de la thèse afin de sonder l'échelle à courte et à moyenne distance. Les propriétés macroscopiques mesurées ont été : la densité, la viscosité et la température de transition vitreuse. Les données issues de cette thèse permettent une meilleure compréhension des changements de structures et des propriétés macroscopiques des verres aluminosilicatés produits par les variations de MO/Al₂O₃ ou SiO₂/Al₂O₃, ou par la nature des cations non-formateurs de réseau. / Three ternary systems (SAS, BAS and ZAS) have been investigated within the framework of the PhD thesis. The main goals were the elaboration and characterization of previously poorly studied Sr, Ba and Zn aluminosilicate glasses. A systematic study has been carried out on glasses and in some cases on melts with various MO/Al₂O₃ (M = Sr, Ba, Zn) and SiO₂/Al₂O₃ ratios. The compositions studied cover a significant part of the ternary diagrams (from silicates to peraluminous glasses, from silica-poor to silica-rich compositions). This allowed expanding our knowledge of the vitrification domains in these systems. In order to obtain information on the structure and macroscopic properties of SAS, BAS and ZAS glasses, a multi-technique approach has been implemented. Such approach allows having a broad view on the systems and finding nano- to microscopic origins of macroscopic properties. The techniques used during the thesis probe short- (NMR, ND) to medium-range (Raman) scale and among the properties studied were density, viscosity and glass transition temperature. The data resulting from this thesis provides a better understanding of the changes in the structure and macroscopic properties of the aluminosilicate glasses produced by variations in MO/Al₂O₃ or SiO₂/Al₂O₃, or by the nature of non-network forming cation.

The dramatic change in properties of water near its critical point (i.e. T = 374 °C and p = 22.1 MPa, note: 100 MPa = 0.1 GPa = 1 kbar ≈ 1000 atm) has been a subject of numerous studies and also lead to the development of various applications (e.g. in waste destruction, biomass processing, and the synthesis of advanced ceramic materials). However, comparatively little is known about the behavior of water at gigapascal pressures. The present study attempts to explore catalytical properties and reactivity of extreme water with respect to several oxide systems: SiO2, TiO2 and LiAlSiO4. “Extreme water” here is defined as existing at p,T conditions of 0.25–10 GPa and 200–1000 °C, thus considering both supercritical fluid and hot compressed ice. The study shows that extreme water can make high pressure mineral phases accessible at relatively mild T conditions. At the same time, high pressure aqueous environments appear efficient in stabilizing novel metastable structures and may be considered as a general route for synthesizing new materials. The hydrothermal treatment of SiO2 glass at 10 GPa and 300–550 °C yielded an unusual ultrahydrous form of stishovite with up to 3% of structural water. At the same time, the extreme water environment enhanced notably the kinetics of stishovite formation, making it accessible at unprecedentedly low temperatures. Thus, for the SiO2–H2O system water acts as both catalyst and reactant. For TiO2 a hydrothermal high pressure treatment proved to be of high importance for overcoming the kinetical hindrance of the rutile – TiO2-II transformation. 6 GPa and 650 °C were established as the mildest conditions for synthesizing pure TiO2-II phase in less than two hours. The crystallization of LiAlSiO4 glass in an extreme water environment yielded a number of different phases. In the low pressure region (0.25 – 2 GPa) mainly a zeolite (Li-ABW) and a dense anhydrous aluminosilicate (α-eucryptite) were obtained. At pressures above 5 GPa the formation of novel pyroxene-like structures with crystallographic amounts of structural water was observed. The overall conclusion of this study is that extreme water environments show a great potential for catalyzing phase transitions in oxide systems and for stabilizing novel structures via structural water incorporation. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.</p>

No description available.

Il est communément admis que les géopolymères sont des solutions potentielles comme alternative aux liants hydrauliques classiques. Les géopolymères sont produits à partir de réactifs non carbonés contrairement au ciment portland et nécessitent relativement peu d'énergie pour être élaborés. Ce sont des liants inorganiques issus de l'activation alcaline d'aluminosilicates. Afin de faire des géopolymères une alternative viable et industriellement intéressante, plusieurs verrous technologiques doivent être levés en particulier sur leur mise en œuvre et les mécanismes chimiques impliqués au très jeune âge. Les études précédentes sur les mécanismes de cette réaction de géopolymérisation montrent l'existence d'un mécanisme en trois phases (dissolution - réorganisation - polymérisation). Notre étude s'est portée sur les mécanismes impliqués dans le comportement à l'état frais et en prise de géopolymère modèle à base de métakaolin. Pour cela, nous avons développé une approche combinée entre les mesures rhéologiques et chimiques (RMN liquide) afin de répondre à la complexité de l'hétérogénéité chimique locale pendant la géopolymérisation. Dans les deux premières parties de la thèse, nous nous sommes intéressés à comprendre le développement des propriétés mécaniques du gâchage à la prise du géopolymère. Lors de mesures de suivi de module élastique au cours du temps, nous observons également trois phases, une première augmentation de module dès les premières centaines de secondes, un plateau caractéristique d'une période de latence puis une seconde augmentation de module après plusieurs heures. Dans un premier temps, nous sommes intéressés à la première augmentation de module. Il a été établi que l'origine de ce module était la formation d'un premier gel de rapport Si/Al < à 4.5 localisé au niveau des joints de grains de métakaolin. Dans un second temps, nous sommes focalisé sur la dernière augmentation de module dont l'origine est la formation d'un second gel dont la composition chimique est celle du produit final c'est-à-dire le géopolymère de rapport Si/Al ~2.Finalement, dans une troisième partie, nous avons mis évidence les principales différences qui existent entre les géopolymères et de ciment Portland d'un point de vue rhéologique. Ces matériaux se comportent comme des fluides newtoniens. Les interactions entre les particules sont dominées par les effets hydrodynamiques, qui sont principalement contrôlés par la viscosité élevée de la solution alcaline de silicate et non par la contribution des contacts directs entre les grains de métakaolin

Made available in DSpace on 2017-07-21T20:43:50Z (GMT). No. of bitstreams: 1 Luiz Cezar Lima Junior.pdf: 4959123 bytes, checksum: 8ba169401ed3c8565f7d14d0d74e19c1 (MD5) Previous issue date: 2016-08-29 / Geopolymers, or ‘inorganic polymers’, considered an alternative cementing system to the convention Portland cement, are formed due to the dissolution, under a high alkali solution, of natural raw materials containing aluminosilicate species. The product of this reaction is the obtainment of a synthetic aluminosilicate product, manufactured under low temperature or even at room temperature. A wide range of materials can be used as precursors as well as alkali activators. The present work focuses on the obtainment of inorganic polymers with innovative precursors, based on different residues of several industrial sectors, such as glass manufacturing, ceramic claddings, and also with local minerals found in abundance on the region of the Campos Gerais. The development of an alternative cementing system will be directly applied on materials to be used as external cladding of steel/wood-based modular structures for residential/commercial buildings, replacing similar materials made from ordinary Portland cement, aiming and industrial application for this product. The obtained product presented similar/superior physical-mechanical properties when compared to its opponent products, with an average flexural strength of 11,73 MPa and a water absorption of 13,50%, being the first value intermediate and the second the best in comparison with commercial products. The use of temperature during curing cycle for increasing the properties of the geopolymeric cement was successfully tested, resulting on more dense and stable structures. Samples showed an increase in flexural strength from 1,83 MPa to 10,15MPa comparing curing cycles at room temperature and at 65ºC, which indicates that temperature works as a setting accelerator for the tested recipe of geopolymers. / Geopolímeros, ou ‘polímeros inorgânicos’, considerados um sistema cimentante alternativo ao cimento Portland convencional, são materiais formados a partir da dissolução de matérias-primas naturais à base de aluminossilicatos em uma solução alcalina. O resultado desta reação é a formação de um aluminossilicato sintético, produzido a baixas temperaturas ou mesmo sob temperatura ambiente. Diferentes matérias-primas naturais e sintéticas podem ser utilizadas como precursores e fonte de álcalis. O presente trabalho tem por objetivo o desenvolvimento de polímeros inorgânicos a partir de precursores inovadores, utilizando-se de resíduos de diversos setores da indústria, tais como da fabricação de vidro, da indústria de revestimentos cerâmicos, e também de insumos locais disponíveis em abundância na região dos Campos Gerais. O sistema cimentante obtido foi utilizado para a obtenção de placas de revestimento em construções em estrutura modular de aço ou madeira, substituindo produtos similares produzidos a partir de cimento Portland convencional, e visando uma aplicação industrial deste. O produto obtido apresentou propriedades físico-mecânicas semelhantes e até superiores às dos produtos concorrentes, com uma resistência à flexão média de 11,73 MPa e uma absorção de umidade média de 13,50%, sendo o primeiro valor intermediário e o segundo o melhor dentre os produtos comerciais. O uso de temperatura para aumento das propriedades físico-mecânicas do cimento geopolimérico foi testado com sucesso, resultando em estruturas mais compactas e estáveis. Houve um aumento de resistência mecânica de 1,83 MPa para 10,15 MPa comparando-se ciclos de cura sob temperatura ambiente e a 65ºC, indicando que a temperatura funciona como um acelerador de cura dos geopolímeros testados.

Cette étude vise à déterminer le transfert et la mobilité d'éléments traces métalliques (ETM), dans des sols de la Réunion destinés à l'épandage de déchets urbains. En plus des fortes teneurs naturelles en ETM, ces sols ont la particularité d'avoir une minéralogie très spécifique avec la présence en abondance de nanoparticules naturelles, communément appelés "imogolites" (nanotubes) et "allophanes" (nanosphères, ovoïdes, amorphe ?). Ces aluminosilicates structurés à courte distance sont susceptibles de piéger les ETM pouvant ainsi limiter leur mobilité et leur biodisponibilité. <br /><br />Dans un premier temps, une étude sur des composés synthétiques analogues aux aluminosilicates a permis d'approfondir nos connaissances sur la structure et les mécanismes de formation des imogolites et allophanes. La synthèse de nanotubes de type imogolite (Si-imogolite et Ge-imogolite) a pu être optimisée ouvrant ainsi les portes à de potentielles applications industrielles. Enfin, notre étude a permis de mettre en avant le rôle important des nanoparticules naturelles sur la dynamique du Ni dans un andosol de la Réunion. Ainsi, près de 80% du Ni est lié aux aluminosilicates structurés à courte distance.

Il est communément admis que les géopolymères sont des solutions potentielles comme alternative aux liants hydrauliques classiques. Les géopolymères sont produits à partir de réactifs non carbonés contrairement au ciment portland et nécessitent relativement peu d'énergie pour être élaborés. Ce sont des liants inorganiques issus de l'activation alcaline d'aluminosilicates. Afin de faire des géopolymères une alternative viable et industriellement intéressante, plusieurs verrous technologiques doivent être levés en particulier sur leur mise en œuvre et les mécanismes chimiques impliqués au très jeune âge. Les études précédentes sur les mécanismes de cette réaction de géopolymérisation montrent l'existence d'un mécanisme en trois phases (dissolution - réorganisation - polymérisation). Notre étude s'est portée sur les mécanismes impliqués dans le comportement à l'état frais et en prise de géopolymère modèle à base de métakaolin. Pour cela, nous avons développé une approche combinée entre les mesures rhéologiques et chimiques (RMN liquide) afin de répondre à la complexité de l'hétérogénéité chimique locale pendant la géopolymérisation. Dans les deux premières parties de la thèse, nous nous sommes intéressés à comprendre le développement des propriétés mécaniques du gâchage à la prise du géopolymère. Lors de mesures de suivi de module élastique au cours du temps, nous observons également trois phases, une première augmentation de module dès les premières centaines de secondes, un plateau caractéristique d'une période de latence puis une seconde augmentation de module après plusieurs heures. Dans un premier temps, nous sommes intéressés à la première augmentation de module. Il a été établi que l'origine de ce module était la formation d'un premier gel de rapport Si/Al < à 4.5 localisé au niveau des joints de grains de métakaolin. Dans un second temps, nous sommes focalisé sur la dernière augmentation de module dont l'origine est la formation d'un second gel dont la composition chimique est celle du produit final c'est-à-dire le géopolymère de rapport Si/Al ~2.Finalement, dans une troisième partie, nous avons mis évidence les principales différences qui existent entre les géopolymères et de ciment Portland d'un point de vue rhéologique. Ces matériaux se comportent comme des fluides newtoniens. Les interactions entre les particules sont dominées par les effets hydrodynamiques, qui sont principalement contrôlés par la viscosité élevée de la solution alcaline de silicate et non par la contribution des contacts directs entre les grains de métakaolin

Conselho Nacional de Desenvolvimento Científico e Tecnológico / This work aimed the synthesis and characterization of pure and doped calcium aluminosilicates using the proteic sol-gel method and by a new route, which combines the proteic sol-gel method with the solid state synthesis. In the proteic sol-gel method, coconut water (Cocos nucifera) is used as a starting solvent. But for the aluminosilicates synthesis, one of the sources of silicon used was the SiO2, which is not soluble in coconut water. Because of that many procedures were tested to synthesize this material. Therefore it was necessary to propose a new hybrid route that would combine different methodologies to produce ceramic powders. For the usual proteic sol-gel methodology, tetraethylortosilicate (TEOS) was used as the source of Si. In order to determine the best conditions of calcination time and temperature for the different routes of calcium aluminosilicate production, thermal analysis and powder x-ray diffraction (DRX) techniques were used. According to the (DTA) analysis, an exothermic peak at 930°C indicates the formation of crystalline phase in the material produced with SiO2. For the one produced whit TEOS, this step is verified around 850°C. From the XRD patterns, it was possible to observe the production of the single crystalline phase in both methodologies, however at different calcination temperatures: 1000°C for the material produced via sol-gel, with TEOS, and 1300°C for the one produced by the hybrid methodology. The crystallite size was evaluated using the Scherrer‟s equation, and the results indicated that the calcined powders in both preparation routes are in nanometric scale. These results were confirmed using the transmission electronic microscopy. Different colorations were observed on the co-doped and calcined doped samples in different conditions. The optical properties of the material were studied and, according to the results obtained using OA, the optical band gap of the Ca2Al2SiO7 system is ~6 ev. It was also observed that the combination of the dopants Ce3+ and Mn2+ indicates an energy transfer process in which the Ce3+ emission, related to the 5d1  4f1 transition, excites resonantly the 6A1(S)  4A1g/4Eg(G) transition of the Mn2+ ion, followed by the emission associated to Mn2+ transitions. Beyond that, the energy level diagram was obtained for the Ce3+ and the transitions associated to the Mn2+ were identified using the Tanabe-Sugano diagram, as a first approximation. / Este trabalho teve como objetivo a produção e a caracterização de pós cerâmicos de aluminosilicatos de cálcio puro e dopado através dos métodos sol-gel protéico e de uma nova rota, a qual combina o método sol-gel protéico à síntese de estado sólido. O método sol-gel protéico utiliza água de coco (Cocos nucifera) como solvente de partida dos precursores solúveis do material a ser obtido. Porém, na produção de aluminosilicatos uma das fontes de silício utilizada foi SiO2, que não é solúvel em água de coco. Em função disso, vários procedimentos foram testados para a síntese desse material. Desta maneira, tornou-se necessária a proposta de uma rota híbrida de produção, a qual combinasse diferentes metodologias para a produção dos pós cerâmicos. Para a metodologia sol-gel protéico usual, utilizou-se tetraetilortosilicato (TEOS) como fonte de Si. A fim de determinar as melhores condições de tempo e temperatura de calcinação nas diferentes rotas de produção, utilizou-se as técnicas de caracterização de análise térmica e DRX. De acordo com as análises de DTA um pico exotérmico em 930°C indica a formação de fases cristalinas no material produzido com SiO2. Para aquele produzido com TEOS essa etapa é verificada em ~850°C. Através da difração de raios-X observou-se a produção da fase cristalina única através das duas metodologias, porém a temperaturas de calcinação diferentes: 1000°C para o material produzido com TEOS, e 1300°C para aquele produzido com SiO2. Fez-se o cálculo do tamanho de cristalito através da equação de Scherrer e este indicou a produção de materiais nanométricos em ambas as rotas de preparação. Esses resultados também confirmados através de MET. Observou-se ainda colorações diferenciadas paras as amostras co-dopadas e dopadas, calcinadas em diferentes condições. De acordo com os resultados das análises ópticas através da absorção óptica, o band gap óptico do sistema Ca2Al2SiO7 foi determinado e é da ordem de ~6 eV. Foram observadas ainda que a combinação dos dopantes Ce3+ e Mn2+ sugerem um processo de transferência de energia na qual a emissão do Ce3+, relacionado com a transição 5d1  4f1, excita ressonantemente a transição 6A1(S)  4A1g/4Eg(G) do íon manganês seguida da emissão associada a transições do Mn2+. O digrama de níveis de energia foi obtido para o Ce3+ e as transições associadas ao Mn2+ foram identificadas através do diagrama de Tanabe-Sugano, como primeira aproximação.

<p>U ovom radu je ispitivan uticaj Antitoksičnognutritiva(ATN), preparata na bazi prirodnih aluminosilikata,na biohemijske, fiziolo&scaron;ke, tehnolo&scaron;ke i proizvodne parametre uzgoja pilića. ATN je sme&scaron;a zeolita klinoptilolita, gline monmorilonita i male količine aktivnog uglja. Dodatak ovog preparata u hranivo za piliće u količini od 5 g/kg nije izazvao promene u normalnoj biohemijskoj i fiziolo&scaron;koj homeostazi životinja. Hematolo&scaron;ki parametri, koncentracija metabolita, elektrolita i aktivnost enzima seruma i jetre je bila u granicama referentnih vrednosti. ATN ne utiče na prirast životinja, ni na konverziju hrane, ali dovodi do povećanja relativnih masa pojedinih organa digestivnog trakta.</p><p>Uočava se da dodatkom ATN-a u hranivo dolazi do smanjenja količine masti a povećanja količine proteina u belom mesu. ATN takođe povećava i sadržaj pepela u<br />belom i crvenom mesu.</p><p>Akutni ili hronični tronedeljni oralni unos pojedinih toksikanata (mikotoksina aflatoksina B1i ohratoksina A, herbicida parakvata, jona olova ili toksina<br />cijanobakterija-mikrocistisa) dovodi do poremećaja normalne biohemijske i fiziolo&scaron;ke homeostaze pojedinih organa i tkiva pilića, &scaron;to je utvrđeno na osnovu rezultata hematolo&scaron;kih i biohemijskih analiza, određivanja enzima antioksidativne za&scaron;tite i lipidne&nbsp;<br />peroksidacije, kao i odredjivanja parametara uzgoja i težine organa. ATN, dodat u hranu u količini od 5 g/kg, mogao da bude dobar protektivni agens za delovanje aflatoksina, parakvata, jona te&scaron;kih metala i mikrocistisa, ali ne i ohratoksina.</p> / <p>This study investigated the effects of dietary supplementation with hydrated aluminosilicate (Antitoxic Nutrient-ATN), based on zeolitic ore (clinoptilolite), clay bentonite (montmorillonite),and small amounts of activated charcoal, on&nbsp; performance, hematological, serum, and liver biochemical parameters, as well as organ weights and meat quality in broiler chickens. The dietary addition of ATN has&nbsp; no adverse effects on serum and liver biochemical parameters and does not affect the normal physiological homeostasis of animals. However, the results of this study demonstrate that supplementation with 5 g/kg of ATN influenced organ weights, and chemical composition of broiler chicken meat.</p><p>This study also evaluated the effectiveness of ATN to protect broilers from adverse effects of five different toxic substances (mycotoxins aflatoxin B1, and ochratoxin A, herbicide paraquat, heavy metal ions supplied as lead-acetate, and microcystis, toxin of cyanobacteria). Toxic substances induced oxidative stress and disturb normal biochemical and physiological homeostasis of different tissues and organs in poultry. The results from this study demonstrate that the biochemical variables of serum, liver, kidney, lung and other organs were negatively affected by all five toxic substances. The additionof 5 g/kg of ATN was protective against aflatoxin B1, lead-acetate, paraquat and microcystis, but not against ochratoxin A.</p>