[pt] A decomposição de sulfatos vem ganhando notoriedade pela sua capacidade de geração limpa de H2 através dos ciclos termoquímicos. O entendimento do mecanismo de decomposição é relevante para futuros planejamentos em aplicações industriais. Além disso, a modelagem desses processos permite obter informações acerca da energia requerida para que os mesmos ocorram. Dentre os diferentes sistemas de reações de decomposição, observa-se que alguns deles são mais complexos do que outros, envolvendo a presença de fases intermediárias e múltiplas reações consecutivas ou simultâneas. Portanto, o presente trabalho se propõe a desenvolver uma metodologia para a modelagem da decomposição térmica de sistemas reacionais com diferentes níveis de complexidade: sulfato de alumínio, alúmen de potássio, mistura de sulfatos de alumínio e potássio, sulfato de zinco e sulfato de ferro (II). Os experimentos foram realizados utilizando análise termogravimétrica (TG) para ter o entendimento dos diferentes estágios de decomposição, utilizando os dados obtidos na etapa de modelagem. O modelo envolveu o uso de um conjunto de equações diferenciais para representar cada uma das reações que ocorrem na decomposição. A estimação dos parâmetros cinéticos feita pelo método de otimização por enxame de partículas. Os resultados indicaram que sistemas envolvendo a decomposição do sulfato de alumínio são catalisados na presença de sulfato de potássio. No caso do zinco, a dessulfatação do sulfato anidro ocorre em duas etapas, com a presença de um oxissulfato como uma fase intermediária. O sulfato de ferro (II) também apresenta uma decomposição complexa ao passar pela fase de sulfato de ferro (III) antes de ser completamento convertido em hematita. Todas as modelagens mostraram excelente ajuste aos dados experimentais, com R2 acima de 0.98 em todos os casos. / [en] The interest over of the decomposition of sulfates has increased due to its capacity of generating clean H2 through the thermochemical cycles. Understanding the decomposition mechanism is relevant to future industrial design and applications. Moreover, the modeling of these processes gives the information needed to know how much energy is required for the occurrence of the reactions. Among the different reaction systems, it is observed a range of complexity, with the presence of intermediate phases, and multiple consecutive or simultaneous reactions. Therefore, the present work proposed to develop a modeling methodology for the thermal decomposition of sulfates systems with different complexity levels: aluminum sulfate, potassium alum, mixture of aluminum sulfate and potassium sulfate, zinc sulfate, and iron (II) sulfate. The experiments were performed using thermogravimetric analysis (TGA) to understand the decomposition stages and use the data in the modeling step. The developed model consisted of a system of differential equations to describe every reaction taking place in the decomposition. The kinetic parameters estimation was made by using particle swarm optimization. The results indicate that potassium sulfate catalyzes the decomposition of aluminum sulfate. In the case of zinc, the desulfation of anhydrous zinc sulfate occurs in two stages, with the presence zinc oxysulfate as an intermediate phase. Iron (II) sulfate also shows a complex decomposition system, as it first decomposes into iron (III) sulfate before it is completely converted into hematite. All the modeling results displayed an excellent agreement with the experimental data, with R2 values above 0.98 for all cases.

[pt] O sulfato de magnésio está presente em diversos rejeitos industriais e de mineração. Ele e seus derivados poderiam ser reaproveitados em várias áreas industriais, deixando de ser um rejeito para se tornar parte de um processo. Seu óxido, MgO, pode ser utilizado em algumas funções, como regulador de pH, dependendo de sua reatividade. Devido a isto sua formação deve ocorrer em temperaturas abaixo das temperaturas de decomposição do MgSO4. Assim sendo este trabalho avaliou aspectos da decomposição do MgSO4 através de dois artigos. O artigo 1 (Thermodynamics Simulations and Kinetics Modeling of the Thermal Decomposition of MgSO4.7H2O: Part 1 – Reducing Agent Effect), avaliou o efeito cinético da utilização do carbono, através de quatro diferentes agentes redutores, na decomposição térmica do MgSO4.7H2O, enquanto que o artigo 2 (Thermodynamics Simulations and Kinetics Modeling of the Thermal Decomposition of MgSO4.7H2O: Part 2 – Hydration Effect) analisou as influências da taxa de aquecimento dos ensaios e do grau de hidratação do sulfato de magnésio utilizado. Os ensaios termogravimétricos realizados ao longo destes artigos, utilizaram amostras com massa de aproximadamente 10 mg de mistura (sulfato + agente redutor) e estas misturas tiveram uma relação estequiométrica de 1:1. Os experimentos realizados no artigo 1, utilizaram como agentes redutores agentes redutores, carvão vegetal, coque verde, coque breeze e grafite. No artigo 2, os sulfatos analisados foram o anidro, o monohidratado e o heptahidratado e as taxas de aquecimento utilizadas foram de 5 K.min(-1) , 10 K.min(-1) , 15 K.min(-1) e 20 K.min(-1) . Todos os dados obtidos dos ensaios termogravimétricos foram processados através de modelagem matemática para se obter os dados cinéticos. No artigo 1 a utilização dos agentes redutores se mostrou eficiente reduzindo a energia de ativação da decomposição do sulfato de magnésio de 22,731 kJ.mol(-1) (sulfato puro) para 340,391 kJ.mol(-1) (coque verde), 196,120 kJ.mol(-1) (grafite), 191,100 kJ.mol(-1) (coque breeze) e 162,302 kJ.mol(-1) (carvão vegetal). No artigo 2, a taxa de aquecimento não se mostrou como um fator determinante para a decomposição do MgSO4, já em relação a hidratação do sulfato de magnésio, os resultados indicaram que uma pequena parcela de H2O no sistema pode influenciar positivamente a decomposição, visto que os valores de Ea médio foram de 404,5 KJ.mol(-1) (mono), 407 KJ.mol(-1) (anidro) e 433,3 KJ.mol(-1) (hepta). / [en] Magnesium sulfate is present in several industrial and mining wastes. It and its derivatives could be reused in various industrial areas, ceasing to be a waste to become part of a process. Its oxide, MgO, can be used in some functions, as a pH regulator, depending on its reactivity. Due to this, its formation must occur at temperatures below the decomposition temperatures of MgSO4. Therefore, this work evaluated aspects of the decomposition of MgSO4 through two articles. Article 1 (Thermodynamics Simulations and Kinetics Modeling of the Thermal Decomposition of MgSO4.7H2O: Part 1 – Reducing Agent Effect), evaluated the kinetic effect of using carbon, through four different reducing agents, on the thermal decomposition of MgSO4.7H2O, while article 2 (Thermodynamics Simulations and Kinetics Modeling of the Thermal Decomposition of MgSO4.7H2O: Part 2 – Hydration Effect) analyzed the influences of the heating rate of the tests and the degree of hydration of the magnesium sulfate used. The thermogravimetric tests carried out throughout these articles used samples with a mass of approximately 10 mg of the mixture (sulfate + reducing agent) and these mixtures had a stoichiometric ratio of 1:1. The experiments carried out in article 1 used reducing agents, charcoal, green coke, breeze coke, and graphite as reducing agents. In article 2, the sulfates analyzed were anhydrous, monohydrate, and heptahydrate and the heating rates used were 5 K.min(-1) , 10 K.min(-1) , 15 K.min(-1) , and 20 K.min(-1). All data obtained from thermogravimetric tests were processed through mathematical modeling to obtain kinetic data. In article 1, the use of reducing agents proved efficient, reducing the activation energy of magnesium sulfate decomposition from 22.731 kJ.mol(-1) (pure sulfate) to 340.391 kJ.mol(-1) (green coke), 196.120 kJ.mol(-1) (graphite), 191,100 kJ.mol(-1) (coke breeze) and 162,302 kJ.mol(-1) (charcoal). In article 2, the heating rate was not shown to be a determining factor for the decomposition of MgSO4, in relation to the hydration of magnesium sulfate, the results indicated that a small portion of H2O in the system can positively influence the decomposition since the average Ea values were 404.5 KJ.mol(-1) (mono), 407 KJ.mol(-1) (anhydrous) and 433.3 KJ.mol(-1) (hepta).

[pt] O hidrogênio apresenta-se como um potencial combustível alternativo em substituição aos combustíveis fósseis e, por essa razão, estudos e pesquisas sobre as rotas de produção e armazenamento desse recurso estão em voga no meio científico. Os métodos para obtenção de H2 são diversos, no entanto, nem todos os métodos são provenientes de fontes renováveis. Os ciclos termoquímicos de quebra da molécula da água são alternativas promissoras para a geração de H2. Neste contexto, o ciclo do enxofre-iodo é um dos ciclos em destaque, caracterizando-se por um processo em três etapas cuja terceira etapa é a etapa desafiadora do ciclo, onde ocorre a decomposição do ácido sulfúrico que exige um gasto energético elevado. A utilização de sulfatos metálicos associados a agentes redutores e aditivos em substituição ao ácido sulfúrico no ciclo enxofre-iodo tem sido estudada. Deste modo, o presente trabalho de pesquisa avaliou a decomposição térmica do sulfato de zinco monohidratado na presença dos agentes modificadores enxofre elementar, Pd-(gama)Al2O3, CeO2 e CeO2/ZnO que estimulam a transformação do trióxido de enxofre no respectivo dióxido. Além de um estudo termodinâmico do sistema reacional e análises térmicas via TG que indicaram uma mudança no comportamento da decomposição do sulfato na presença do agente redutor e dos aditivos, o trabalho previu a caracterização dos produtos reacionais indicando a presença do óxido de zinco e um estudo cinético dos sistemas na presença dos agentes mencionados, permitindo o cálculo das energias de ativação e dos parâmetros cinéticos. A apreciação termodinâmica indicou um aspecto favorável quanto a diminuição da temperatura de decomposição do sulfato de zinco assim como no que diz respeito à transformação de SO3 em SO2. Na presença de Pd-(gama)Al2O3 a temperatura final da decomposição do sulfato ocorreu 100 graus Celsius abaixo da temperatura habitual. A perda de massa total calculada para a decomposição do sulfato puro foi de 55 por cento. Nos estudos com a presença dos agentes as perdas de massa total calculadas foram 60 por cento, 54 por cento, 62 por cento, 57 por cento correspondentes ao sulfato de zinco na presença do enxofre elementar, Pd-(gama)Al2O3, CeO2 e CeO2/ZnO, respectivamente. / [en] Hydrogen presents itself as a potential alternative fuel to replace fossil fuels and, for this reason, studies and research on the production and storage routes of this resource are in vogue in the scientific community. The methods for obtaining H2 are diverse, however, not all methods are from renewable sources. The thermochemical cycles of splitting water are promising alternatives. In this context, the sulfur-iodine cycle is one of the highlighted cycles, characterized by a three-stage process whose third stage is the challenging stage of the cycle, where the decomposition of sulfuric acid occurs, which requires a high energy expenditure for formation selection of sulfur dioxide and oxygen. The use of metal sulfates associated with reducing agents and additives in substitution for sulfuric acid in the sulfur-iodine cycle has been studied. Thus, the present research work evaluated the thermal decomposition of zinc sulfate monohydrate in the presence of elemental sulfur modifying agents, Pd- (gamma)Al2O3, CeO2 and CeO2 / ZnO that stimulate the transformation of sulfur trioxide in the respective dioxide. In addition to a thermodynamic study of the reaction system and thermal analyzes via TGA that indicated a change in the sulphate decomposition behavior in the presence of the reducing agent and additives, the work predicted the characterization of the reaction products indicating the presence of zinc oxide and a study kinetics of the systems in the presence of the mentioned agents, allowing the calculation of activation energies and kinetic parameters. The thermodynamic assessment indicated a favorable aspect regarding the decrease in the decomposition temperature of zinc sulfate as well as with regard to the transformation of SO3 into SO2. In the presence of Pd-(gamma)Al2O3, the final temperature of the sulphate decomposition occurred 100 C degrees below the usual temperature. The total mass loss calculated for the decomposition of pure sulfate was 55 percent. In studies with the presence of agents, the calculated total mass losses were 60 percent, 54 percent, 62 percent, 57 percent corresponding to zinc sulfate in the presence of elemental sulfur, Pd-(gamma)Al2O3, CeO2 and CeO2 / ZnO, respectively.

Le kérogène, fraction insoluble de la matière organique sédimentaire, est un mélange complexe et hétérogène de macromolécules organiques. Ces structures évoluent, essentiellement sous l’effet de la température, au cours des temps géologiques et génèrent les hydrocarbures présents dans les bassins sédimentaires. Comprendre et quantifier les mécanismes physicochimiques associés à ce processus est important pour l’estimation des réserves pétrolières. Au cours de cette étude, deux géopolymères ont été sélectionnés pour représenter la décomposition thermique de structures typiques des kérogènes naturels. Dans un premier temps, une étude expérimentale nous a permis (1) de proposer des structures moléculaires des géopolymères et (2) de décrire les mécanismes primaires de décomposition des géopolymères. Les échantillons ont été analysés au moyen d’expériences de pyrolyse en milieu confiné à cinq températures de référence comprises entre 200 à 300°C. Un schéma cinétique correspondant aux processus précoces de décomposition a été établi à partir des observations expérimentales pour chacun des deux géopolymères. Dans un deuxième temps, les modèles moléculaires élaborés dans l'étape précédente ont été soumis à des simulations moléculaires dynamiques utilisant un champ de forces réactif (ReaxFF). Ces simulations ReaxFF ont apporté une interprétation théorique aux processus-clés observés expérimentalement. L’ensemble des résultats de cette étude suggère que les modèles cinétiques, en une étape implémentés dans les simulateurs de bassin standard ne reproduisent pas correctement la physicochimie des processus de décomposition de la matière organique dans les roches mères naturelles / Kerogen, the insoluble fraction of sedimentary organic matter, is a complex mixing of organic macromolecules, the structure of which evolves during geological times as a function of temperature mainly. The thermal evolution of kerogen is at the origin of hydrocarbon deposits in sedimentary basins. Understanding and quantifying the physicochemical processes associated to this transformation is therefore important to improve the evaluation of petroleum systems. During this study, two geopolymers were selected in order to represent the thermal decomposition of typical structures in natural kerogen. Firstly, an experimental protocol was set up (1) to define molecular structures of the geopolymers, and (2) to describe primary mechanisms of decomposition of both geopolymers. The two samples were analysed using off-line pyrolysis experiments, at five reference temperatures comprised between 200 to 300°C. A kinetic scheme accounting for early decomposition processes was derived from these experimental observations for each geopolymer. Secondly, molecular models were submitted to molecular dynamic simulations using a reactive force field (ReaxFF). ReaxFF simulations provided theoretical supports to the key-processes derived from laboratory experiments. On the overall, results of this study suggested that kinetic models in one step (= parallels reactions implemented in standard (commercial) basin simulators do not adequately reproduce the physicochemistry of organic matter decomposition processes in natural source rocks

Iron platinum (FePt) has attracted growing interest because of its high Curie temperature, magneto-crystalline anisotropy and chemical stability. Nanoparticles (NPs) made of this alloy are promising candidates for a wide range of biomedical applications including magnetic separation, magnetic targeted drug delivery, hyperthermia for cancer therapy and also as magnetic resonance imaging (MRI) contrast agents. This thesis presents the synthesis, functionalization and characterization of FePt NPs along with a toxicity study and an investigation into their application as MRI contrast agents. Regarding their synthesis, different approaches have been explored including the co-reduction of Fe and Pt precursors in an aqueous media, the thermal decomposition in a conventional high-boiling solvent such as benzyl ether, and in low-melting organic salts (ionic liquids). The data revealed an inhomogeneous composition distribution of Fe and Pt between particles obtained in aqueous media, due to the iron salts hydrolysis, and a mismatch in the co-reduction kinetic of the two metal precursors. While the iron content in the NPs could be increased by using more hydrolytically stable iron precursors or stronger reducing agents, there are remaining limiting parameters which prevent further Fe content increase in NPs. In contrast, by excluding the water from the reaction system and using a Fe²⁻ iron precursor, homogenous 1:1 Fe to Pt ratio NPs can be obtained through a modified thermal decomposition pathway in benzyl ether. Based on the study of synthesis in this conventional chemical, the potential of ionic liquids (ILs) to be used as novel solvents for FePt NPs synthesis was further explored. It was then demonstrated that ionic liquids (ILs) can not only be used as a solvent for synthesis of FePt NPs, but also can provide an exciting alternative pathway to direct synthesis fct-FePt NPs. In the context of the bioapplication of FePt NPs, a family of FePt NPs was specifically designed to enhance their MRI contrast agents properties. In contrast with previous reports, this thesis demonstrates that FePt NPs can be made non-toxic and provides the first data on their cellular uptake mechanisms. A six times increase in the FePt based T₂ contrast properties compared to clinical iron oxide NPs is reported. The relationship between the MRI contrast properties and the NPs architecture is explored and rationalised as the basis for the design of NPs as enhanced MRI contrast agents. Finally, the first observations of cellular and in vivo MR imaging with FePt NPs is also reported. This study opens the way for several applications of FePt NPs such as regenerative medicine and stem cell therapy, thus providing a bio-platform to develop novel diagnostic and therapeutic agents.

Atualmente, a participação da energia elétrica na matriz energética mundial é um assunto em evidência. O estudo do compósito isolante da barra estatórica, um dos componentes principais da máquina hidrogeradora, permite a obtenção de informações físico-químicas relevantes ao aperfeiçoamento do sistema, e também de estudos de comportamento térmico quando este é exposto à alta temperatura, por diferentes intervalos de tempo submetidos a estresses mecânicos, elétricos e/ou químicos. O sistema em estudo é o MICALASTIC®, desenvolvido pela empresa Siemens em 1960. Neste trabalho, as propriedades térmicas do compósito isolante, formado por uma fita de mica, resina epóxi (DGEBA), endurecedor (MHHPA) e acelerador naftenato de zinco (N-Zn) foram estudadas. Utilizando-se as técnicas termoanalíticas Calorimetria Exploratória Diferencial (DSC) e Termogravimetria e Termogravimetria Derivada (TG/DTG), o comportamento térmico de cada um dos materiais foi avaliado. As curvas DSC e TG/DTG também evidenciaram as possíveis interações químicas entre os componentes. Os estudos referentes à cura do material e da degradação térmica do compósito curado foram realizados. Observou-se claramente a influência da quantidade de acelerador na polimerização do sistema. A partir das curvas DSC, observou-se dois mecanismos de cura diferentes coexistentes, um com menor quantidade de N-Zn e outro com concentração maior, resultando em eventos de cura com início em temperaturas diferentes. Esse fato ainda não havia sido estudado desde a origem do sistema. Além disso, a perda de massa referente à evaporação do endurecedor no início do processo de cura foi confirmada a partir da caracterização do compósito por espectroscopia de absorção na região do infravermelho, comparando-se os espectros antes e após o fenômeno. Na prática, dois perfis de impregnação, o Homogêneo e o Heterogêneo, de barras condutoras são utilizados, e uma diferença significativa entre eles foi observada. Os estudos desenvolvidos devem ser associados a testes elétricos específicos para o melhor entendimento da relação entre a aplicação do material e suas propriedades teóricas termoanalíticas. Além disso, foi realizado o estudo cinético da decomposição térmica do compósito curado por métodos termogravimétricos, isotérmico e dinâmico. / Currently, the electric energy participation in the world energy matrix is a significant issue. The insulating composite in stator bars, which are one of the most important components in hydrogenerator machines, allows the attainment of relevant physical and chemical information to system optimization, in addition to study thermal behavior when the material is exposed to high temperatures, for different time intervals and mechanical, chemical and/or electrical stress. The studied system is MICALASTIC®, developed by Siemens Company in 1960. In this work, thermal properties of this insulating composite, composed by mica tape, epoxy resin (DGEBA), hardener (MHHPA) and zinc naphtenate (N-Zn) as accelerator, were studied. Using thermoananalytical techniques as Differential Scanning Calorimetry (DSC) and Thermogravimetry and Derivative Thermogravimetry (TG/DTG), thermal behavior of each material was evaluated. DSC and TG/DTG curves evidenced chemical interactions between components. The study relative to material curing and cured composite thermal degradation were described. It was clearly observed the N-Zn amount influence in the cure of system, and through DSC curves, it was possible to observe two distinct polymerization coexisting mechanisms, one with lower quantity of N-Zn and another one with bigger concentration, resulting in cure events starting in different temperatures. This fact has not been studied yet since the system has been originated. Besides that, the weight loss related to hardener evaporation starting with curing process was confirmed by composite characterization by FTIR spectra, before and after phenomenon. In practice, two impregnation patterns (Homogeneous and Heterogeneous) of conductive bars are used and a significant difference between them was observed. The developed studies have to be associated to electrical tests to a best understanding about material application and theoretical thermoanalytical properties. In addition, it was performed thermal decomposition of cured composite kinetic study by isothermic and dynamic thermogravimetric methods

It is well known that nanostructures possess unique electronic, optical, magnetic, ferroelectric and piezoelectric properties that are often superior to traditional bulk materials. In particular, one dimensional (1D) nanostructured inorganic materials including nanofibres, nanotubes and nanobelts have attracted considerable attention due to their distinctive geometries, novel physical and chemical properties, combined effects and their applications to numerous areas. Metal ion doping is a promising technique which can be utilized to control the properties of materials by intentionally introducing impurities or defects into a material. γ-Alumina (Al2O3), is one of the most important oxides due to its high surface area, mesoporous properties, chemical and thermal properties and its broad applications in adsorbents, composite materials, ceramics, catalysts and catalyst supports. γ-Alumina has been studied intensively over a long period of time. Recently, considerable work has been carried out on the synthesis of 1D γ-alumina nanostructures under various hydrothermal conditions; however, research on the doping of alumina nanostructures has not been forthcoming. Boehmite (γ-AlOOH) is a crucial precursor for the preparation of γ-Alumina and the morphology and size of the resultant alumina can be manipulated by controlling the growth of AlOOH. Gallium (Ga) is in the same group in the periodic table as aluminum. β-Gallium (III) oxide (β-Ga2O3), a wide band gap semiconductor, has long been known to exhibit conduction, luminescence and catalytic properties. Numerous techniques have been employed on the synthesis of gallium oxide in the early research. However, these techniques are plagued by inevitable problems. It is of great interest to explore the synthesis of gallium oxide via a low temperature hydrothermal route, which is economically efficient and environmentally friendly. The overall objectives of this study were: 1) the investigation of the effect of dopants on the morphology, size and properties of metal ion doped 1D alumina nanostructures by introducing dopant to the AlOOH structure; 2) the investigation of impacts of hydrothermal conditions and surfactants on the crystal growth of gallium oxide nanostructures. To achieve the above objectives, trivalent metal elements such as iron, gallium and yttrium were employed as dopants in the study of doped alumina nanostructures. In addition, the effect of various parameters that may affect the growth of gallium oxide crystals including temperature, pH, and the experimental procedure as well as different types of surfactants were systematically investigated. The main contributions of this study are: 1) the systematic and in-depth investigation of the crystal growth and the morphology control of iron, gallium and yttrium doped boehmite (AlOOH) under varying hydrothermal conditions, as a result, a new soft-chemistry synthesis route for the preparation of one dimensional alumina/boehmite nanofibres and nanotubes was invented; 2) systematic investigation of the crystal growth and morphology and size changes of gallium oxide hydroxide (GaOOH) under varying hydrothermal conditions with and without surfactant at low temperature; We invented a green hydrothermal route for the preparation of α-GaOOH or β-GaOOH micro- to nano-scaled particles; invented a simple hydrothermal route for the direct preparation of γ-Ga2O3 from aqueous media at low temperature without any calcination. The study provided detailed synthesis routes as well as quantitative property data of final products which are necessary for their potential industrial applications in the future. The following are the main areas and findings presented in the study: • Fe doped boehmite nanostructures This work was undertaken at 120ºC using PEO surfactant through a hydrothermal synthesis route by adding fresh iron doped aluminium hydrate at regular intervals of 2 days. The effect of dopant iron, iron percentage and experimental procedure on the morphology and size of boehmite were systematically studied. Iron doped boehmite nanofibres were formed in all samples with iron contents no more than 10%. Nanosheets and nanotubes together with an iron rich phase were formed in 20% iron doped boehmite sample. A change in synthesis procedure resulted in the formation of hematite large crystals. The resultant nanomaterials were characterized by a combination of XRD, TEM, EDX, SAED and N2 adsorption analysis. • Growth of pure boehmite nanofibres/nanotubes The growth of pure boehmite nanofibres/nanotubes under different hydrothermal conditions at 100ºC with and without PEO surfactant was systematically studied to provide further information for the following studies of the growth of Ga and Y doped boehmite. Results showed that adding fresh aluminium hydrate precipitate in a regular interval resulted in the formation of a mixture of long and short 1D boehmite nanostructures rather than the formation of relatively longer nanofibres/nanotubes. The detailed discussion and mechanism on the growth of boehmite nanostructure were presented. The resultant boehmite samples were also characterized by N2 adsorption to provide further information on the surface properties to support the proposed mechanism. • Ga doped boehmite nanostructures Based on this study on the growth of pure boehmite nanofibre/nanotubes, gallium doped boehmite nanotubes were prepared via hydrothermal treatment at 100ºC in the presence of PEO surfactant without adding any fresh aluminium hydrate precipitate during the hydrothermal treatment. The effect of dopant gallium, gallium percentage, temperature and experimental procedure on the morphology and size of boehmite was systematically studied. Various morphologies of boehmite nanostructures were formed with the increase in the doping gallium content and the change in synthesis procedure. The resultant gallium doped boehmite nanostructures were characterized by TEM, XRD, EDX, SAED, N2 adsorption and TGA. • Y doped boehmite nanostructures Following the same synthesis route as that for gallium doped boehmite, yttrium doped boehmite nanostructures were prepared at 100ºC in the presence of PEO surfactant. From the study on iron and gallium doped boehmite nanostructures, it was noted both iron and gallium cannot grow with boehmite nanostructure if iron nitrate and gallium nitrate were not mixed with aluminium nitrate before dissolving in water, in particular, gallium and aluminium are 100% miscible. Therefore, it’s not necessary to study the mixing procedure or synthesis route on the formation of yttrium doped boehmite nanostructures in this work. The effect of dopant yttrium, yttrium percentage, temperature and surfactant on the morphology and size of boehmite were systematically studied. Nanofibres were formed in all samples with varying doped Y% treated at 100ºC; large Y(OH)3 crystals were also formed at high doping Y percentage. Treatment at elevated temperatures resulted in remarkable changes in size and morphology for samples with the same doping Y content. The resultant yttrium doped boehmite nanostructures were characterized by TEM, XRD, EDX, SAED, N2 adsorption and TGA. • The synthesis of Gallium oxide hydroxide and gallium oxide with surfactant In this study, the growth of gallium oxide hydroxide under various hydrothermal conditions in the presence of different types of surfactants was systematically studied. Nano- to micro-sized gallium oxide hydroxide was prepared. The effect of surfactant and synthesis procedure on the morphology of the resultant gallium oxide hydroxide was studied. β-gallium oxide nanorods were derived from gallium oxide hydroxide by calcination at 900ºC and the initial morphology was retained. γ-gallium oxide nanotubes up to 65 nm in length, with internal and external diameters of around 0.8 and 3.0 nm, were synthesized directly in solution with and without surfactant. The resultant nano- to micro-sized structures were characterized by XRD, TEM, SAED, EDX and N2 adsorption. • The synthesis of gallium oxide hydroxide without surfactant The aim of this study is to explore a green synthesis route for the preparation of gallium oxide hydroxide or gallium oxide via hydrothermal treatment at low temperature. Micro to nano sized GaOOH nanorods and particles were prepared under varying hydrothermal conditions without any surfactant. The resultant GaOOH nanomaterials were characterized by XRD, TEM, SAED, EDX, TG and FT-IR. The growth mechanism of GaOOH crystals was proposed.

Atualmente, a participação da energia elétrica na matriz energética mundial é um assunto em evidência. O estudo do compósito isolante da barra estatórica, um dos componentes principais da máquina hidrogeradora, permite a obtenção de informações físico-químicas relevantes ao aperfeiçoamento do sistema, e também de estudos de comportamento térmico quando este é exposto à alta temperatura, por diferentes intervalos de tempo submetidos a estresses mecânicos, elétricos e/ou químicos. O sistema em estudo é o MICALASTIC®, desenvolvido pela empresa Siemens em 1960. Neste trabalho, as propriedades térmicas do compósito isolante, formado por uma fita de mica, resina epóxi (DGEBA), endurecedor (MHHPA) e acelerador naftenato de zinco (N-Zn) foram estudadas. Utilizando-se as técnicas termoanalíticas Calorimetria Exploratória Diferencial (DSC) e Termogravimetria e Termogravimetria Derivada (TG/DTG), o comportamento térmico de cada um dos materiais foi avaliado. As curvas DSC e TG/DTG também evidenciaram as possíveis interações químicas entre os componentes. Os estudos referentes à cura do material e da degradação térmica do compósito curado foram realizados. Observou-se claramente a influência da quantidade de acelerador na polimerização do sistema. A partir das curvas DSC, observou-se dois mecanismos de cura diferentes coexistentes, um com menor quantidade de N-Zn e outro com concentração maior, resultando em eventos de cura com início em temperaturas diferentes. Esse fato ainda não havia sido estudado desde a origem do sistema. Além disso, a perda de massa referente à evaporação do endurecedor no início do processo de cura foi confirmada a partir da caracterização do compósito por espectroscopia de absorção na região do infravermelho, comparando-se os espectros antes e após o fenômeno. Na prática, dois perfis de impregnação, o Homogêneo e o Heterogêneo, de barras condutoras são utilizados, e uma diferença significativa entre eles foi observada. Os estudos desenvolvidos devem ser associados a testes elétricos específicos para o melhor entendimento da relação entre a aplicação do material e suas propriedades teóricas termoanalíticas. Além disso, foi realizado o estudo cinético da decomposição térmica do compósito curado por métodos termogravimétricos, isotérmico e dinâmico. / Currently, the electric energy participation in the world energy matrix is a significant issue. The insulating composite in stator bars, which are one of the most important components in hydrogenerator machines, allows the attainment of relevant physical and chemical information to system optimization, in addition to study thermal behavior when the material is exposed to high temperatures, for different time intervals and mechanical, chemical and/or electrical stress. The studied system is MICALASTIC®, developed by Siemens Company in 1960. In this work, thermal properties of this insulating composite, composed by mica tape, epoxy resin (DGEBA), hardener (MHHPA) and zinc naphtenate (N-Zn) as accelerator, were studied. Using thermoananalytical techniques as Differential Scanning Calorimetry (DSC) and Thermogravimetry and Derivative Thermogravimetry (TG/DTG), thermal behavior of each material was evaluated. DSC and TG/DTG curves evidenced chemical interactions between components. The study relative to material curing and cured composite thermal degradation were described. It was clearly observed the N-Zn amount influence in the cure of system, and through DSC curves, it was possible to observe two distinct polymerization coexisting mechanisms, one with lower quantity of N-Zn and another one with bigger concentration, resulting in cure events starting in different temperatures. This fact has not been studied yet since the system has been originated. Besides that, the weight loss related to hardener evaporation starting with curing process was confirmed by composite characterization by FTIR spectra, before and after phenomenon. In practice, two impregnation patterns (Homogeneous and Heterogeneous) of conductive bars are used and a significant difference between them was observed. The developed studies have to be associated to electrical tests to a best understanding about material application and theoretical thermoanalytical properties. In addition, it was performed thermal decomposition of cured composite kinetic study by isothermic and dynamic thermogravimetric methods

Les émissions des NOₓ par l'industrie métallurgique proviennent principalement de la combustion du charbon au cours du procédé d'agglomération. Parmi les méthodes de réduction des NOₓ de ce procédé, l'ajout des additifs dans le mélange de matières premières du procédé d'agglomération a été choisi grâce à ses avantages. Ces techniques sont relativement simples à mettre en oeuvre, et ne nécessitent qu'un faible coût d'investissement. Cette thèse est une partie du projet européen INTERREG IVA CleanTech et du projet industriel d'ArcelorMittal de Dunkerque, qui portent sur les études de réductions de NOₓ par méthode d'ajout des additifs. L'objectif de cette thèse consiste à étudier le mécanisme de réduction des NOₓ par ces additifs afin d'optimiser le procédé et de choisir des nouveaux additifs. De plus, les propriétés des produits d'agglomérés sont également étudiées pour déterminer l'influence des additifs sur les qualités de produit final. Une première étude expérimentale a été consacrée à l'étude de la décomposition thermique des additifs utilisés afin de comprendre le mécanisme de diminution des NOₓ. Nous avons pu déterminer des composés-réducteurs de NOₓ et des quantités formées au cours de la pyrolyse des additifs. Cela nous permet de confirmer les produits influençant sur la réduction des NOₓ. Dans une deuxième partie, les produits d'agglomérés obtenus lors des essais dans la cuve pilote, ont été mesurés par différentes méthodes (diffraction X au laboratoire, diffraction X à haute énergie et haute résolution sur synchrotron, spectroscopie Mössbauer). Nous avons d'abord déterminé les compositions des phases cristallines contenus dans les agglomérés. Nous avons ensuite comparé les différences entre les agglomérés références (sans additifs) et les agglomérés obtenus avec différents additifs afin de déterminer les phases responsables pour la résistance mécanique. / NOₓ emission in the steel industry mainly come from the combustion of coal in the agglomeration process. Among the methods of NOₓ reduction for this process, the addition of additives to the mixture of raw materials agglomeration process is chosen due to its advantages. This technique is comparatively simple to implement, and requires only a low-cost investment. This thesis is part of European project INTERREG IVA CleanTech and industrial project ArcelorMittal Dunkerque in order to study NOₓ reductions by additives. The objectives of this thesis is to have a better comprehension in the mechanism of NOₓ reduction by additives to optimize the process with more effective additives. With that purpose, the properties of agglomerated products are also studied to determine the additives' influences on the quality of the final product. In the first part, an experimental study was devoted to sutdy the thermal decomposition of the additives to understand the mechanism of NOₓ reduction. The compounds formed during the pyrolysis of additives are identified and quantified. This allows us to confirm the products' influence on the reduction of NOₓ. In the second part, agglomerated products obtained in the pilot test are measured by different methods (X-ray diffraction laboratory, high-energy and high-resolution X-ray diffraction, Mössbauer spectroscopy). To determine the compositions of crystalline phases contained in the agglomerates. We then compared the differences between the reference agglomerate (without additives) and agglomerate obtained with different additives in order to determine the phases related to the mechanical resistance.

Die vorliegende Arbeit beschäftigt sich mit der Darstellung von paramagnetischen diskreten mono-, di- und multinuklearen sowie polymeren Koordinationsverbindungen. Der Schwerpunkt dieser Arbeit bildet neben der chemischen und strukturellen Charakterisierung die magnetische Charakterisierung mittels SQUID-Magnetometrie und ESR-Spektroskopie. Für eine Reihe von Koordinationsverbindungen wurden darüber hinaus die thermischen Stabilitäten bzw. das Zersetzungsverhalten als auch die gebildeten Rückstände untersucht. Des Weiteren werden multinukleare Koordinationsverbindungen vorgestellt, die sich der Klasse der „Metallo-dendrimere“ zuordnen lassen. Im Sinne einer konvergenten Dendrimersynthese wurde an Poly(amidoamin)-Dendrimere (PAMAM) carbonsäurefunktionalisierte Bis(oxamat)-Leweis-Basen kovalent angebunden und anschließend mit CuII-Ionen komplexiert. Die so isolierten endständigen mononuklearen Einheiten konnten durch eine weitere Komplexierung mit {Cu(pmdta)}2+-Komplexfragmenten und unter Ausnutzung ihrer flexidentaten Eigenschaften in trinukleare {CuII}3-Einheiten überführt werden. Da die CuII-Ionen aller individuellen {CuII}3-Einheiten über intramolekulare magnetische Austauschwechselwirkungen verfügen, können diese Verbindungen als „Magnetodendrimere“ bezeichnet werden, wobei die magnetischen Eigenschaften sich aus der Summe der individuellen Bausteine zusammensetzen. Ein dendritischer Effekt ist in dieser Dendrimerengröße nicht erkennbar. Ein weiterer Schwerpunkt der Arbeit war die Synthese formiatbasierender NiII-, CoII und CuII- Komplexe und deren magnetischer sowie thermischer Charakterisierung. In der Regel werden mononukleare Komplexe vorgestellt, die im festen Zustand aber auch mittels Wasserstoffbrückenbindungen 1D-, 2D- oder auch 3D-Netzwerke ausbilden. Auf die potentielle Eignung dieser Komplexe als Präkursoren zur Niedertemperaturgenerierung reiner Metalle, wie z.B. in Druck- oder Fügeprozessen, wird eingegangen. Basierend auf die im Rahmen dieser Arbeit erreichten Ergebnissen zu dinukleare NiII-haltigen Formiatkomplexen, wurde ein strukturell analoger NiII- als auch CoII-haltiger Vertreter mit Ferrocenylcarboxylatdonoren synthetisiert und die magnetischen, elektrochemischen und thermischen Eigenschaften bestimmt. Als zusätzliche Weiterentwicklung der Thematik formiathaltiger Komplexverbindungen wurden die 3D-aufgebauten Übergangsmetallformiate [{MII(O2CH)2}∙2H2O] (MII = Mn, Co, Ni) unter solvothermalen Bedingungen mit dem N-Donoren Pyridin umgesetzt. Die so erhaltenen MnII- und CoII-haltigen Edukte sind 2D-aufgebaute Addukte des Typs [M(O2CH)2(py)m]n (M = Mn, m = 2; M =Co, m = 7), die via π-π-Wechselwirkungen ihrer Pyridinliganden 3D-Netzwerke ausbilden. Die Struktur dieser Komplexverbindungen sowie deren Stabilität nach Isolation ihrer Feststoffe werden diskutiert.:Bibliografische Beschreibung und Referat I Ort und Zeitraum der Durchführung III Inhaltsverzeichnis IV Selbständigkeitserklärung VI Präambel VII Abkürzungsverzeichnis VIII Kapitel A – Einleitung 1 Kapitel B – Kenntnisstand 7 1. Carboxylatoliganden als Mediatoren von magnetischen Austauschwechselwirkungen 8 2. Bis(oxamato)-Liganden als Mediatoren von magnetischen Austauschwechselwirkungen 10 3. Dendrimere und der dendritische Effekt 17 4. Der Strukturtyp [M2(O2CR)4(H2O)(LN)2] 25 5. Thermische Zersetzungsreaktionen von Formiatverbindungen und die Reduktion der Zersetzungstemperaturen derer im Allgemeinen 29 6. Motivation 34 C – Publikation: CuII bis(oxamato) end-grafted poly(amidoamine) dendrimers 36 D – Publikation: Tri- (M = CuII) and hexanuclear (M = NiII, CoII) heterometallic complexes with ferrocene monocarboxylate and chelating diamines as ligands 58 E.1 – Publikation: Nickel(II) Formate Complexes with Bi- and Tridentate Nitrogen-based Ligands: Synthesis, Solid State Structures, Thermal and Magnetic Properties 68 E.2 – Weiterführende Diskussion: Das thermische Zersetzungsverhalten von stickstoffhaltigen Metallformiat-Verbindungen 86 F.1 – Poster: Synthesis of poly- and monomeric transition metal complexes with formato and pyridine ligands. 91 F.2 – Vorbereitende Arbeiten für ein Manuskript: Darstellung und kristallografische Beschreibung von 2D-polymeren und diskreten Metall-Pyridin-Komplexen 93 Kapitel G – Zusammenfassung 106 Literaturverzeichnis 110 Danksagung 119 Lebenslauf 120