La réaction de films minces métalliques avec un substrat de silicium reste encore peu étudiée dans le domaine des très faibles épaisseurs. Afin de suivre les cinétiques de réaction et l'évolution des contraintes lors de la formation d'une phase, des mesures de diffraction du rayonnement X synchrotron, et de courbure de substrat ont été couplées. Le système Pd/Si constitue un système modèle ; un siliciure unique se forme : Pd2Si. Les résultats obtenus prouvent que le modèle de Zhang et d'Heurle permet d'expliquer l'évolution des contraintes résultant de la compétition de deux mécanismes : le développement de contraintes en compression dû à la formation d'une nouvelle phase et la relaxation des contraintes du siliciure déjà formé. Néanmoins, la microscopie électronique en transmission et les figures de pôle révèlent que la texture de cette phase change selon l'orientation du substrat. Sur Si(111), Pd2Si est en épitaxie alors que sur Si(001), la phase présente une texture qui évolue au cours du traitement thermique. Cette évolution serait activée par un mécanisme de fluage diffusionnel puis par de la déformation plastique. L'étude de films ultra-minces de Ni montre qu'il existe une épaisseur critique (<6 nm) en dessous de laquelle la séquence de phases et la texture des siliciures formés sont modifiées. Différentes techniques révèlent qu'à partir de 200 °C, la phase NiSi croît sous la forme d'une couche homogène et continue. En augmentant la température, les phases NiSi et NiSi2 coexistent avec différentes morphologies : îlots pénétrant dans le substrat ou bâtonnets.

Des carbones dérivés de carbures à porosité monodisperse et nanocentrée autour de 0,6 nm ont été préparés par fluoration de carbures via l'arrachement sélectif de l'élément métallique et le maintien de l'empreinte carbonée initiale. Les carbures précurseurs ont été choisis parmi deux des classes de carbures à savoir interstitiels pour le carbure de titane et de niobium et covalents pour le carbure de silicium. La fluoration directe procédant sous flux d'une atmosphère de fluor pur apparait comme étant la seule méthode de fluoration apte à déstabiliser les poudres cristallisées. Appliquée au carbure de titane, des matériaux à teneur variable en carbone et en trifluorure de titane ont été obtenus et caractérisés structuralement par Diffraction des Rayons X quantitative, spectroscopies IR et Raman et leur texture sondée par Microscopie Electronique à Balayage et à Transmission et isothermes d'adsorption à l'azote à 77K. Ils ont aussi été évalués comme matériau d'électrode de supercondensateurs. La fluoration du carbure de silicium pour la stabilisation d'une phase carbonée est plus difficile et seule l'abaissement de la cristallinité du carbure par l'utilisation d'une mise en forme de type couche mince combinée à une méthode de fluoration alternative par décomposition de l'agent fluorant XeF2 ont permis d'obtenir une couche mince de carbone nanostructurée valorisable comme lubrifiant solide et aux propriétés de mouillabilité modulables.

Dans les piles primaires au lithium, l'anode de lithium peut être couplée principalement à quatre matériaux de cathode (MnO2, SO2, SOCl2 et des composés fluorés CFx). Les piles Li/CFx présentent de nombreux avantages tels qu'une densité d'énergie élevée (jusqu'à 2200 Wh.kg-1), un potentiel de décharge relativement élevé (environ 2,4 V vs Li+/Li) et une longue durée de vie (plus de 10 ans à la température ambiante). Au cours de ce travail, nous avons intensément étudié les propriétés électrochimiques des carbones fluorés nanostructurés. Pour plus de performances, des précurseurs nanocarbonés de dimensionnalité différentes, et des procédés de synthèse gaz-solide variés ont été employés. Ainsi, des structures fermées comme les nanofibres de carbone (1D, tubulaire), ouvertes comme les nanodisques / nanocônes (2D en majorité, discotiques) et intermédiaires avec les noirs de carbone graphitisés. Chaque mode de synthèse a été optimisé en fonction du précurseur de départ (son facteur de forme, sa dimensionnalité, son degré de graphitisation ...). Pour remédier aux limitations des carbones fluorés commerciaux, leur mécanisme de décharge a été finement étudié afin d'améliorer notre compréhension sur la défluoration électrochimique d'une cathode CFx, et de les comparer aux CFx synthétisés au laboratoire, le but principal étant de dépasser les performances actuelles et de synthétiser des matériaux inédits pour la pile primaire au lithium. Des extracapacités par rapport aux valeurs théoriques dans les batteries Li/CFx ont été obtenues avec de nanocarbones fluorés spécifiques et le phénomène électrochimique à l'origine de cette extracapacité a été clairement expliqué.

Submitted by Emanuel Varela Cardoso (emanuel.varela@ufcg.edu.br) on 2018-06-26T19:38:51Z No. of bitstreams: 1 POLYANA TARCIANA ARAÚJO DOS SANTOS – TESE (UAEMa) 2015.pdf: 2974694 bytes, checksum: 08e52baa2c42ce5e7b0e35cbf00934bd (MD5) / Made available in DSpace on 2018-06-26T19:38:51Z (GMT). No. of bitstreams: 1 POLYANA TARCIANA ARAÚJO DOS SANTOS – TESE (UAEMa) 2015.pdf: 2974694 bytes, checksum: 08e52baa2c42ce5e7b0e35cbf00934bd (MD5) Previous issue date: 2015-01-29 / CNPq / Neste trabalho de pesquisa foi obtido um material híbrido a base de nanoferritas Ni0,5Zn0,5Fe2O4 e CoFe2O4 modificada a superfície com agente silano e funcionalizadas com quitosana visando seu uso como biossensores. Para este fim, as nanoferritas foram sintetizadas por reação de combustão e silanizadas com o 3-aminopropiltrimetoxissilano. A funcionalização foi realizada pelo método de evaporação do solvente usando o biopolímero quitosana. Todas as amostras foram caracterizadas por difração de raios X, espectrometria de infravermelho por transformada de Fourier, espectroscopia por energia dispersiva de raios X, análise termogravimétrica, microscopia eletrônica de varredura, microscopia eletrônica de transmissão, teste de sedimentação e separação magnética, medidas magnéticas e análise in vitro por citotoxidade. As amostras como sintetizadas apresentaram a formação da fase única do espinélio em estudo com característica nanométrica e após a formação do híbrido a estrutura do material foi mantida. Nos espectros de infravermelho observaram-se bandas de absorção características das nanoferritas e bandas referentes à presença do agente silano e da quitosana. Por meio das micrografias observou-se a formação de aglomerados de aspecto frágil, e após silanização e funcionalização observou-se uma morfologia com aglomerados de aspecto mais rígido constituídos de nanopartículas fortemente ligadas. A análise termogravimétrica mostrou que as nanoferritas apresentaram baixa perda de massa e que após formação do híbrido houve um aumento da perda de massa comprovando assim, a presença do agente silano e da quitosana. Quanto ao comportamento magnético, ambas as nanoferritas apresentaram elevada magnetização de saturação típica de materiais ferrimagnéticos, este comportamento foi mantido após formação do híbrido sendo adequado para aplicações biotecnológicas. A viabilidade celular das nanoferritas mostrou característica citotóxica para a ferrita Ni0,5Zn0,5Fe2O4 e não citotóxica para a ferrita CoFe2O4, a formação do híbrido favoreceu aumento da viabilidade celular em ambas as nanoferritas. Os materiais híbridos obtidos são promissores para o uso na nanobiotecnologia como biossensores e/ou em tratamento como diagnóstico clinico. / In this research was obtained a hybrid material nanoferrit es base Ni0,5Zn0,5Fe2O4 and CoFe2O4 modified the surface with silane agent and functionalized chitosan aiming their use as biosensors. To this end, nanoferritas were synthesized by combustion and silanized with 3-aminopropyltrimethoxysilane. The functionalization was carried out by the solvent evaporation method using the biopolymer chitosan. All samples were characterized by X-ray diffraction, infrared spectroscopy by Fourier transform spectroscopy energy dispersive X-ray, thermal analysis, scanning electron microscopy, transmission electron microscopy, sedimentation test and magnetic separation, magnetic measurements and Analysis by in vitro cytotoxicity. The samples showed synthesized as the formation of spinel single phase with nanometer feature under study and after the formation of the hybrid structure of the material has been maintained. In the infrared spectra there were absorption bands characteristic of nanoferritas and bands related to the presence of the silane agent and chitosan. Through micrographs showed the formation of agglomerates frail and after silanization and functionalization was observed with a morphology more rigid aspect of tightly bound agglomerates of nanoparticles. Thermogravimetric analysis showed that the nanoferritas showed low weight loss and that after hybrid formation was increased mass loss thereby proving the presence of the silane agent and chitosan. As for the magnetic behavior, both nanoferritas had high magnetization typical saturation ferrimagnetic materials, this behavior continued after the hybrid formation is suitable for biotechnological applications. Cell viability nanoferritas showed characteristic for cytotoxic and non-cytotoxic ferrite Ni0,5Zn0,5Fe2O4 to CoFe2O4 ferrite, the formation of hybrid favored increased cell viability in both nanoferritas. The obtained hybrid materials are promising for use in nanobiotechnology as biosensors and / or treatment and clinical diagnosis.

La mise au point de nouveaux matériaux pour piéger les anions phosphate présents dans les eaux usées est une des clés pour lutter contre le phénomène d’eutrophisation des eaux de surface. Au cours de cette étude, les hydroxydes doubles lamellaires contenant des ions CaII et FeIII dans les feuillets cationiques et des anions chlorure et nitrate au sein de l’espace inter-feuillets (CaFe-HDL-Cl et CaFe-HDL-NO3) ont été utilisés pour piéger les phosphates. Ces deux variantes d’HDL ont été synthétisées par trois méthodes simples de co-précipitation. La capacité de piégeage de ces matériaux a été évaluée par des expériences de sorption en « batch » à l’équilibre et des mesures de cinétique dans une gamme de pH comprise entre 4 et 12. La cinétique de piégeage du phosphate par les HDL obéit à une loi du pseudo-second ordre. Les isothermes révèlent que les HDL synthétisés avec un rapport CaII : FeIII de 2 : 1 sont les plus efficaces pour piéger les phosphates. On mesure des capacités de piégeage très élevées de l’ordre de 385 et 402 mg g-1 pour les composés CaFe-HDL-Cl et CaFe-HDL-NO3, respectivement. Les données obtenues à l’équilibre ont pu être ajustées par des isothermes de type Langmuir et/ou Freundlich. Pour des concentrations en phosphate élevées ([PO43-] ≥ 100 mg L-1), la caractérisation des solides et des liquides par diverses techniques révèlent que la HDL se dissout et libèrent des cations solubles Ca2+ qui précipitent avec les phosphates pour former l’hydroxyapatite Ca5(PO4)3OH. A ce mécanisme principal s’ajoute un mécanisme de piégeage secondaire qui est l’adsorption des phosphates par un gel ferrique dopé en ions calcium qui est lui aussi issu de la transformation minéralogique de l’HDL. A faible concentration en phosphate ([PO43-] ≥ 100 mg L-1), l’hydroxyapatite ne se forme pas et l’adsorption des phosphates par ce gel ferrique dopé en ions calcium devient le mécanisme de piégeage principal. / The development of an efficient removal material for phosphate from wastewater to prevent the eutrophication in surface waters is very important. In this study, CaIIFeIII layered double hydroxide containing chloride and nitrate as intercalated anions (CaFe-LDH-Cl and CaFe-LDH-NO3) were used as removal materials for phosphate. Both forms were designed and synthesized at different CaII: FeIII molar ratios (2:1, 3:1, and 4:1) following three simple co-precipitation methods. The materials were evaluated for the removal of phosphate by batch equilibrium sorption experiments and kinetic measurements. The efficiency of the phosphate removal from aqueous solution was investigated in the range pH 4-12. As a result, it was found that pseudo-second-order kinetic model described well the phosphate removal. The isotherms of adsorption of PO43- ions showed that CaFe-LDH-Cl and CaFe-LDH-NO3 at CaII: FeIII molar ratio of 2:1 revealed the highest rate of phosphate uptake of 385 and 402 mg g-1, respectively, comparing to other CaII: FeIII molar ratios. Equilibrium data were well fitted with Freundlich and Langmuir isotherms. In the case of high phosphate concentration ([PO43-] ≥ 100 mg L-1), the comprehensive analysis of the phosphate-uptake products with different techniques revealed that CaFe-LDH dissolve first and then released Ca2+ ions reacting with PO43- anions to form Ca5(PO4)3OH (hydroxyapatite) which is the main mechanism for phosphate removal. Also, phosphate was removed partially via a subsidiary process other than precipitation of hydroxyapatite. The excess in phosphate removal was attributed to the formation of a disordered Ca doped ferrihydrite which removed phosphate via simple surface adsorption. In the case of initial low phosphate concentration ([PO43-] < 100 mg L-1), the analysis showed that PO43- removed mainly via simple surface adsorption over disordered Ca doped ferrihydrite which was the main component in the residual solid after partial Ca2+ releasing from LDH

Submitted by Alison Vanceto (alison-vanceto@hotmail.com) on 2017-02-16T16:22:40Z No. of bitstreams: 1 DissBCDO.pdf: 4309058 bytes, checksum: 4f5cf3d0dbedd0e22b67ee37cbc653e9 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-03-13T18:12:23Z (GMT) No. of bitstreams: 1 DissBCDO.pdf: 4309058 bytes, checksum: 4f5cf3d0dbedd0e22b67ee37cbc653e9 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2017-03-13T18:12:35Z (GMT) No. of bitstreams: 1 DissBCDO.pdf: 4309058 bytes, checksum: 4f5cf3d0dbedd0e22b67ee37cbc653e9 (MD5) / Made available in DSpace on 2017-03-13T18:20:51Z (GMT). No. of bitstreams: 1 DissBCDO.pdf: 4309058 bytes, checksum: 4f5cf3d0dbedd0e22b67ee37cbc653e9 (MD5) Previous issue date: 2015-09-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Pharmaceutical cocrystals are multicomponent crystalline solids comprised of an active pharmaceutical ingredient (API) and one or more co-formers interacting through hydrogen bonding or other weak interactions like the π-stack and van der Waals interactions. Fluconazole (FLZ) is a triazole antifungal drug used in the treatment and prevention of superficial and systemic fungal infections. It is also used to prevent and treat meningitis. Cocrystallization is an alternative approach for enhancement of drug. It can be performed using neat grinding, solvent assisted grinding, solvent evaporation, cooling evaporation and slurry cocrystallization. In this work, a new cocrystal Fluconazol-Fumaric acid monohydrate was synthesized via 1:1 stoichiometric amount of FLZ and FUM at different conditions. The characterization of the synthesized cocrystals was achieved using Raman spectroscopy, differential scanning calorimetry, powder X-ray diffraction and single crystal X-ray diffraction. The results obtained for the characterization of the samples showed some obvious differences among the spectra, diffractograms and thermograms. The single crystal X-ray diffraction analysis of the new structure shows a cocrystal where the fluconazole molecules are attached to the fumaric acid and water molecules respectively through hydrogen bonds, gave unique cell dimensions for an assumed structure C17H18F2N6O6 with a space group of P21/n, a = 17.053(3) Å, b = 5.5995(10), c=21.154(3), α = 90°, β=105.418(4)°, γ= 90°, V = 1947.3(6) Å3. This work is the first to report a monohydrate cocrystal structure of fluconazole and fumaric acid. / Cocristais farmacêuticos são sólidos cristalinos multi-componentes compostos de um ingrediente ativo farmacêutico (API) e um ou mais co-formadores interagindo através de ligações de hidrogênio ou outras interações fracas como as π-stack e Van der Waals. Fluconazol (FLZ), é um fármaco anti-fúngico triazol utilizado no tratamento e prevenção de infecções fúngicas superficiais e sistémicas. É também utilizado para prevenir e tratar a meningite. Cocristalização é uma abordagem alternativa para melhorar as propriedades de fármacos. Pode ser realizada através de moagem a seco, moagem assistida por solvente, evaporação de solvente e cristalização em suspensão. Neste trabalho, um novo co-cristal Fluconazol-Ácido Fumarico monohidrato foi sintetizado utilizando uma estequimetria 1:1 em diferentes condições. A caracterização dos co-cristais sintetizados foi realizada utilizando espectroscopia Raman, calorimetria exploratória diferencial, difração de raios-X em pó é por monocristal. Os resultados obtidos para a caracterização das amostras mostrou algumas diferenças obvias entre os espectros, difratogramas e termogramas. A difração de raios-X de monocristal mostrou uma nova estrutura onde as moléculas de fluconazol estão ligadas ao ácido fumárico e a uma molécula de água através de ligações de hidrogênio, originando uma estrutura única C17H18F2N6O6 de grupo espacial P21/n e dimensões da célula unitária a = 17.053(3) Å, b = 5.5995(10), c=21.154(3), α = 90°, β=105.418(4)°, γ= 90°, V = 1947.3(6) Å3. Este trabalho é o primeiro a relatar uma estrutura de co-cristal mono-hidrato de fluconazol e acido fumárico.

No description available.

Made available in DSpace on 2014-12-17T14:58:13Z (GMT). No. of bitstreams: 1 RaquelGC_DISSERT.pdf: 1617455 bytes, checksum: fe137c67d61e0483bac922261c815e1e (MD5) Previous issue date: 2011-11-23 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / In this study we used the plasma as a source of energy in the process of carbothermic reduction of rutile ore (TiO2). The rutile and graphite powders were milled for 15 h and placed in a hollow cathode discharge produced by in order to obtain titanium carbonitride directly from the reaction, was verified the influence of processing parameters of plasma temperature and time in the synthesis of TiCN. The reaction was carried out at 600, 700 and 800&#730;C for 3 to 4 hours in an atmosphere of nitrogen and argon. During all reactions was monitored by plasma technique of optical emission spectroscopy (EEO) to check the active species present in the process of carbothermal reduction of TiO2. The powder obtained after the reactions were characterized by the techniques of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The technique of EEO were detected in all reactions the spectra CO and NO, and these gas-phase resulting from the reduction of TiO2. The results of X-ray diffraction confirmed the reduction, where for all conditions studied there was evidence of early reduction of TiO2 through the emergence of intermediate oxides. In the samples reduced at 600 and 700&#730;C, there was only the phase Ti6O11, those reduced to 800&#730;C appeared Ti5O9 phases, and Ti6O11 Ti7O13, confirming that the carbothermal reduction in plasma, a reduction of the ore rutile (TiO2) in a series of intermediate titanium oxide (TinO2n-1) where n varies between 5 and 10 / Neste trabalho foi utilizado o plasma como fonte energ?tica no processo de redu??o carbot?rmica do min?rio rutilo (TiO2). Os p?s de rutilo e grafite foram mo?dos durante 15 h e introduzidos numa descarga produzida por c?todo oco a fim de obter carbonitreto de tit?nio diretamente da rea??o, sendo verificado a influ?ncia dos par?metros de processamento de plasma, temperatura e tempo na s?ntese de TiCN. As rea??o foram efetuadas a 600, 700 e 800&#730;C por 3 e 4 horas numa atmosfera de nitrog?nio e arg?nio. Durante todas as rea??es o plasma foi monitorado pela t?cnica de espectroscopia de emiss?o ?ptica (EEO) para verificar as esp?cies ativas presente no processo de redu??o carbot?rmica de TiO2. Os p?s obtidos ap?s as rea??es foram caracterizados pelas t?cnicas de difra??o de raios X (DRX) e microscopia eletr?nica de varredura (MEV). Pela t?cnica de EEO foram detectados em todas as rea??es os espectros CO e NO, sendo essas fases gasosas resultante da redu??o do TiO2. Os resultados de difra??o de raios X confirmou essa redu??o, onde para todas as condi??es estudadas houve evid?ncia de in?cio da redu??o do TiO2 atrav?s do aparecimento de ?xidos intermedi?rios. Nas amostras reduzidas a 600 e 700&#730;C observou-se apenas a fase Ti6O11, naquelas reduzidas a 800 &#730;C apareceram as fases Ti5O9, Ti6O11 e Ti7O13, comprovando que com a redu??o carbot?rmica em plasma, houve redu??o do min?rio rutilo (TiO2) em uma s?rie de ?xido intermedi?rios de tit?nio (TinO2n-1) onde n varia entre 5 e 10

Cette thèse porte sur l’étude du processus de cristallisation de verres et l’élaboration de vitrocéramiques transparentes dans le visible. Ce travail a permis d’élaborer plusieurs vitrocéramiques complètement cristallisées et transparentes, ce qui constitue un résultat exceptionnel pour ce type de matériaux qui perd habituellement la transparence lors de la cristallisation. Ces matériaux originaux et novateurs ont fait l’objet d’un brevet sur des "Céramiques transparentes" (dépôt en France N° 1161025 et extension internationale PCT N° EP2012/074171) et de plusieurs articles (cf. page 162). Plusieurs verres dans les systèmes oxydes de terres rares-oxydes d’alcalino-terreux-Al2O3-SiO2 ont été élaborés au moyen d’un lévitateur aérodynamique couple a un chauffage par laser puis étudiés. Une recherche de la composition optimale du verre d’aluminosilicate d’yttrium parent qui permettrait d’avoir un maximum de cristaux de YAG sans formation d’impuretés lors de la cristallisation a été menée. L’étude de la cristallisation du YAG a partir des verres d’aluminosilicates d’yttrium choisis, réalisée principalement par RMN et diffraction des rayons X, a montré que les ions de silicium initialement présents dans la matrice vitreuse se trouvent incorporés dans les cristaux de YAG formes, en substitution des ions d’aluminium des sites tétraédriques. Les conséquences structurales de cette incorporation dans le YAG ont été étudiées. En particulier, la réduction de la maille cubique du YAG et des liaisons des sites tétraédriques a été mise en évidence par DRX et affinement Rietveld. Par RMN, la présence d’aluminium en coordinence IV, V et VI a été détectée dans le verre parent. Pour ce système, il est remarquable que la cristallisation du verre d’aluminate d’yttrium puisse avoir lieu au-dessous de sa température de transition vitreuse. Ce phénomène rarement rapporté pourrait être expliqué par la tendance élevée du verre à cristalliser et par la capacité de Si4+ à s’incorporer dans les cristaux de YAG comme cette étude le démontre. L’avancement de la cristallisation par recuit du verre au-dessous de Tg a été suivi ainsi que l’absorbance et la diffusion de l’irradiation IR par les vitrocéramiques en se basant sur le modèle de Rayleigh-Guns-Debye. Cette étude a révélé l’influence de la différence de l’indice de réfraction entre le verre et les cristaux sur la diffusion de la lumière. Les images MET et MEB de ces vitrocéramiques montrent des cristaux de YAG de tailles comprises entre 500 nm et 1300 nm. La cristallisation d’une autre famille de verres de terres rares a été étudiée. Il s’agit de verres d’aluminate de lanthane et de borate de lanthane. Dans les deux cas, une cristallisation démarrant à partir de la surface a été observée et étudiée. La cristallisation des phases LaAlO3 et LaBO3 dans ces verres a été suivie par DRX (Haute Température). L’ajout de SiO2 à la composition La2O3-Al2O3 a été nécessaire pour élaborer un verre avec un four classique. Une étude de cristallisation poussée a été également menée sur de nouveaux verres d’aluminates d’alcalinoterreux. Cette étude a compris une caractérisation des vitrocéramiques formées ainsi que la résolution de la structure de deux nouveaux polymorphes de BaAl4O7 formés par cristallisation des verres en se servant de la diffraction électronique, neutronique et synchrotron. Une étude par RMN de l’évolution de l’environnement de l’oxygène durant le recuit a été réalisée et a permis de mettre en évidence la présence des entités d’oxygène tri-coordinées dans les verres d’aluminate de baryum. Ce travail nous a finalement permis d’élaborer plusieurs vitrocéramiques complètement cristallisées et transparentes, ce qui constitue un résultat exceptionnel. La luminescence de ces vitrocéramiques a été caractérisée et les raisons de leur transparence sont discutées à la lumière de leurs microstructures. / This thesis concerns the crystallization and the structural study of different alumino-silicate glasses. This study has led to several completely crystallized and transparent glass-ceramics, which is an original result for this type of material that usually loses transparency during crystallization. These innovative materials were the subject of a patent entitled “Transparent ceramics” (French deposit number: N° 1161025 and international extension number : PCT N° EP2012/074171) and different articles (cf. page 162). Numerous glasses in the systems rare earth oxides, alkaline earth oxides-Al2O3-SiO2 were prepared by an aerodynamic levitator coupled to a laser heating system and studied. The study of the YAG crystallization from the yttrium alumino-silicate glasses was achieved mainly by double resonance 27Al/29Si NMR spectroscopy and by (lab and synchrotron) X-ray diffraction. This study showed that the silicon ions that are initially present in the glassy matrix are incorporated during crystallization in the formed YAG crystals on the 4-fold coordination Al site. The structural consequences of this incorporation were studied. In particular, the reduction of the YAG cubic lattice and the bonds of the tetrahedral sites have been evidenced. Upon post synthesis annealing, the glass was observed to exhibit crystallization below the glass transition temperature. This unusual behaviour was examined using XRD and infrared spectroscopy to follow crystallinity and optical absorbance as a function of annealing treatment. This rarely reported phenomenon could be explained by the high tendency of our glass to crystallize compared to glasses elaborated by classical furnaces and by the ability of Si4+ to be accommodated into the YAG crystal structure as we have demonstrated. This study also revealed the influence of the refractive index difference between the glass and the crystals on the scattering of light. TEM and SEM images show that the YAG crystals sizes range between 500 nm and 1300 nm. Furthermore, the crystallization of a family of lanthanum aluminate and lanthanum borate glasses was studied. In both cases, the crystallization started from the surface. The formation of LaAlO3 LaBO3 phases in these glasses was followed by XRD (High Temperature). The addition of SiO2 to the Al2O3-La2O3 composition was found necessary for the vitrification with a conventional oven. Finally, a crystallization study was also conducted on new alkaline-earth aluminate glasses. This study included a characterization of the parent glasses with the formed glass-ceramics and the structure resolution of two new polymorphs of BaAl4O7 formed by crystallization, using electron neutron and synchrotron diffraction. An NMR study of the environment evolution of the oxygen during annealing was performed. This allowed to evidence the presence of tri-coordinated oxygen entities in the parent glasses. This work has finally allowed us to develop fully crystallized and transparent glass-ceramics, which is an exceptional result. The luminescence of these glass-ceramics was characterized and the reasons for their transparency were discussed in light of their microstructures.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The materials characterization techniques, especially the X-ray diffratometry (XRD) and the X-ray fluorescence spectroscopy (XRF) has been well developed since the x-ray discovery at the end of XIX century, the x-ray diffraction phenomena by crystals at the beginning of XX century. Despite the two techniques derived from a common scenario, the quantitative X-ray fluorescence spectroscopy has been an advance more slowly, when compared to X-ray diffractometry. This lead the XRF to bee more knowledge by quick and fast qualitative analyses. By other side XRD technique has the quantitative principles established since the 50 decade of the last century. Around the 80 decade a increase of the interest about the quantitative procedures was did due to the possibility of the numerical treatment of the Sherman equations. This lead to a minimize the need of a individual standards in XRF. Many algorithms was described in the scientific literature about the XRF and it was the main interest in these mastering degree development, because in later times was development an first software by the group with goal the understand so well the quantification methodologies involving in chemical analysis by XRF. This work has as the main subject the validation of a new version of the software IILXRF2012, which was subject of a later mastering in the research group. / As técnicas de caracterização de materiais, em especial a difratometria de raios X (DRX) e a espectroscopia de fluorescência de raios X (FRX) tem se desenvolvido a passos largos desde a descoberta dos raios X no final do século XIX e da observação do fenômeno de difração dos raios X por cristais no início do século XX. Embora essas duas técnicas, de certa forma, sejam derivadas de um cenário comum, a interação dos raios X com a matéria, a espectroscopia de fluorescência de raios X teve um avanço, do ponto de vista quantitativo mais lento do que a difratometria de raios X. Isso levou a técnica de FRX a ser mais conhecida pela realização rápida de análises qualitativas do que quantitativas enquanto que técnica de DRX desde o final da década de 50 do último século já possuía os fundamentos do refinamento de estruturas, algo que atualmente nem é mais novidade. Todavia em meados da década de 80 do século passado houve um significativo aumento do interesse na técnica de FRX devido a possibilidade de tratamento numérico das equações de Sherman desenvolvidas em meados da década de 50 que forneciam o caminho matemático para a determinação quantitativa elemental através de uma análise teórica, praticamente eliminando a necessidade de padronização. Em razão disso diversos algoritmos foram sendo desenvolvidos ao longo das últimas décadas e no intuito de uma compreensão de como esse tipo de medida é possível, uma dissertação de mestrado foi defendida pela nossa equipe procurando explorar os conceitos envolvidos nessas análises. Em razão dos resultados serem promissores decidiu-se pela continuidade desse trabalho procurando-se uma implementação efetiva da metodologia desenvolvida para análise quantitativa de FRX via resolução numérica das equações de Sherman. Para tanto escolheu-se um conjunto de materiais para testes no intuito de validar uma nova versão do software IILXRF2012, cuja primeira versão foi objeto do desenvolvimento do trabalho de dissertação anterior.