This work has two interlocking themes. It is primarily concerned with the development of precise, broad band, Fourier transform spectrometric techniques for the determination of the optical constants of solids at millimetre and submillimetre wavelengths. One such technique cannot easily accomodate the wide range of optical constants found in solids, leading to specimens which range from the virtually transparent to the virtually opaque, and it was therefore necessary to develop transmission and reflection techniques. The intercomparison of these techniques, their particular experimental difficulties and susceptibilities to random and systematic error, was performed by using each method to determin'the optical constants of soda lime silica glass over as wide a spectral range as possible. Previous to this work there had been no systematic study of this important material at these wavelengths and,thus, this investigation gave the second theme of this work, the quantitative determination of the optical constants of soda lime silica glass at millimetre and submillimetre wavelengths. The results of this study are presented in four chapters. First, in chapter 5, power transmission Fourier transform spectrometry has been used to investigate the spectral variation of the optical constants of the glass between 3 and 50cm, using an analysis of channel spectra to give the refractive index. This chapter also contains the results of measurements made with a grating instrument between 1000 and k000cm. Secondly, in chapter 6, the results of the first direct determinations of the optical constants by dispersive transmission Fourier transform spectrometry are presented and shown to indicate the presence of a hitherto unknown loss process below 20er that is tentatively associated with a similar process previously observed in fused silica. Thirdly, in chapter 7, dispersive reflection Fourier transform spectrometry has been used to determin the optical constants up to 360em, well into the midinfrared region of opacity of this glass. The results of chapters 6 and 7 provide the first quantitative description of the optical constants of this glass betweem 3 and 360em Finally, in chapter 8, the dispersive reflection measurements are extended to simple binary and ternary silicate glasses, and these results used to identify the contributions to the mid-infrared absorption of the metal ions associated with the various metal oxide additives of the glass. From this it was possible to account for all of the absorption in soda lime silica glass as a superposition of contributions from the near-infrared bands of the SiO1 network of the glass and the four main metal ions.

Phénomène brutal et encore mal connu, la reprise d'altération se traduit par une subite accélération de la vitesse d'altération du verre, due à la déstabilisation de la couche amorphe et passivante préalablement formée à sa surface. En comprendre l'origine, et en mesurer les conséquences, sont des enjeux majeurs pour la prédiction du comportement à long terme des verres nucléaires.Cette étude lie quantitativement le degré d'altération d'un verre de référence à six oxydes et les mécanismes de formation des zéolithes et C-S-H qui contrôlent la chimie de la solution. Le rôle d'indicateur de reprise joué par la décroissance de la concentration en aluminium est mis en évidence. Il apparaît qu'occurrence et vitesse de reprise sont corrélées au couple (T, pH) ; même dans les situations les plus défavorables, la vitesse de reprise reste inférieure d'un ordre de grandeur environ à la vitesse initiale d'altération, qui reste le régime cinétique le plus rapide. Jusqu'alors limitée aux pH alcalins, une nouvelle approche est mise en œuvre pour étendre la caractérisation des reprises d'altération dans des conditions plus représentatives de celles d'un stockage géologique. Elle a nécessité le développement d'un outil : l'ensemencement qui réduit, voire supprime, la période de latence précédant la reprise. Les résultats obtenus en font un puissant outil pour la compréhension du rôle joué par les zéolithes sur la déstabilisation de la pellicule amorphe et pour la modélisation des reprises d'altération. Une démarche de modélisation géochimique du phénomène de reprise est proposée en s'appuyant sur le formalisme du modèle GRAAL. Elle repose sur le calcul des constantes thermodynamiques des zéolithes, sur l'implémentation de leurs lois cinétiques de nucléation et de croissance et sur des hypothèses relatives à la solubilité de la couche amorphe. Lorsque la précipitation des zéolithes consomme des alcalins, l'altération du verre — dont elle est le moteur — en libère. Le modèle éclaire l'importance de tels couplages chimiques et montre que, dans la stœchiométrie des verres nucléaires, leurs effets cumulés sont à l'origine d'une diminution du pH limitant à son tour la précipitation des zéolithes. / A sudden and still poorly understood phenomenon, the resumption of alteration results in a sudden acceleration of the glass alteration rate due to the destabilization of the amorphous passivating layer formed on the glass surface. Understanding the origin and the consequences of this phenomenon is a major issue for the prediction of nuclear glass long-term behavior.This study quantitatively links the alteration degree of a six-oxide reference glass and the formation mechanisms of zeolites and C-S-H that control the solution chemistry. The role played by the decrease in aluminum concentration as an indicator of resumption is highlighted. It appears that the resumption occurrence and rate are correlated to the couple (T, pH), but even in the most adverse situations the resumption rate is lower than the initial alteration rate, which remains the fastest kinetic regime. Previously limited to alkaline pH, the characterization of alteration resumptions was extended to conditions more representative of those found in a geological repository. This approach required the development of a new tool: seeding, that reduces or eliminates the latency period preceding a resumption. The results obtained demonstrate its usefulness in understanding the role of zeolites in amorphous layer destabilization and for modeling alteration resumptions.A geochemical modeling approach to alteration resumption is proposed, based on the formalism of the GRAAL glass alteration model. It is based on the calculation of zeolite thermodynamic constants, on the implementation of their nucleation and growth kinetics, and on assumptions related to the solubility of the amorphous layer. When zeolite precipitation consumes alkali, glass alteration—driven by zeolite precipitation—releases alkali. The model highlights the importance of such chemical couplings and shows that, in the stoichiometry of French nuclear reference glass, their cumulative effects are the cause of a pH decrease which limits zeolite precipitation.

Made available in DSpace on 2017-07-21T19:25:46Z (GMT). No. of bitstreams: 1 Iolanda Cristina Dechandt.pdf: 4265751 bytes, checksum: 63e41222d90f6a9011f71a3cac7991d8 (MD5) Previous issue date: 2015-03-06 / Fundação Araucária de Apoio ao Desenvolvimento Científico e Tecnológico do Paraná / Progress in medicine has led to an increase in life expectancy of the world population. On the other hand, the properties of certain tissues and organs that compose the human body continues to follow the aging process. Faced with this challenge, biomaterial are developed with new technologies for bone substitutes. In this study we investigated the bioactivity of the glasses system 2Na2O.1CaO.3SiO2 with 0, 3 and 6% P2O5 in weight. The bioactivity was studied by immersion in simulated body fluid solution. Heat treatments were also performed in order to study the bioactivity of these glass-ceramics. Differential scanning calorimetry was performed to determine the glass transition temperatures for the glasses. Through Fourier transform infrared spectroscopy analysis was used to verify the bioactivity. The hardness and elastic modulus of the glasses were determined by the instrumented nanoindentation. X-ray diffraction confirmed the crystalline phases present in the glass ceramic samples. It was observed the formation of a hydroxycarbonate apatite layer after 21 days in samples of glass 2Na2O.1CaO.3SiO2 with 0, 3 and 6% P2O5 in weight. The best condition for the growth of hydroxycarbonate apatite layer in the glass-ceramics was the 2Na2O.1CaO.3SiO2 + 3% P2O5 that received heat treatment of 15 hours at 560° C. We observed the growth of the hydroxycabonate apatite layer after 7 days, and the glass-ceramic 2Na2O.1CaO.3SiO2+6% P2O5 who received heat treatment of 15 hours at 560° C the hydroxycabonate apatite layer was observed after 14 days in vitro novel. It was observed that cristalyzation is reduced with increase P concentration. At glass-ceramics with 6%wt of P2O5 the crystals are richer in Ca than in the stoichiometric glass matrix. In opposition, for 1Na2O2NaO3SiO2 glass-ceramics, the crystals are richer in Na.x / Os avanços na medicina vêm levando a um aumento na expectativa de vida da população mundial, por outro lado o desgaste de certas propriedades de tecidos e órgãos que compõe o corpo humano continua acompanhando o processo de envelhecimento. Frente a esse desafio os biomateriais são desenvolvidos com novas tecnologias para substituir ossos. Nesta pesquisa investigamos a bioatividade dos vidros no sistema 2Na2O.1CaO.3SiO2-P2O5 com 0, 3 e 6% em peso de P2O5. A bioatividade foi investigada pela imersão das amostras em solução de fluido corpóreo simulado. Realizados tratamentos térmicos a fim de verificar a bioatividade em vitrocerâmicas. Por meio da calorimetria exploratória diferencial determinamos os valores de temperatura de transição vítrea dos vidros. Através das análises de Infravermelho por transformada de Fourier pudemos verificar a bioatividade dos vidros. Analises de indentação instrumentada determinaram a dureza e o módulo de elasticidade dos vidros. A difração de raios X nos forneceu as fases cristalinas presentes nas amostras vitrocerâmicas. Foi verificado a formação de uma camada de hidroxicarbonato de apatita após 21 dias nas amostras de vidro 2Na2O.1CaO.3SiO2 com 0, 3 e 6% em peso de P2O5. A melhor condição para o crescimento da camada de hidroxicarbonato de apatita nos vitrocerâmicos foi 2Na2O.1CaO.3SiO2 + 3% P2O5 que recebeu tratamento térmico por 15 horas a 560°C. Nos observamos a camada de hidroxiapatita após 7 dias, e o vitrocerâmico 2Na2O.1CaO.3SiO2+6% P2O5 que recebeu tratamento por 15 horas a camada hidroxiapatita foi observada após 14 dias de ensaio in vitro. Foi observado que a cristalização é reduzida com o aumento da concentração de P. No vitrocerâmico com 6% em peso de P2O5 os cristais são mais ricos em Ca do que na matriz vítrea estequiométrica. Por outro lado, o vitrocerâmico com a fase 1Na2O2NaO3SiO2 os cristais são ricos em Na.

Neste trabalho foram estudados novos eletrólitos poliméricos e vidros fosfatos utilizando a técnica de Ressonância Magnética Nuclear. Os eletrólitos estudados foram o poliéster (etileno glicol / ácido cítrico - EG/AC) e os filmes de hidroxietilcelulose (HEC) entrecruzados com diisocianatos de poli (óxido de etileno) e poli (óxido de propileno), ambos dopados com sais de lítio No estudo dos eletrólitos poliméricos, foram realizadas medidas da forma de linha e da taxa de relaxação spin-rede do 1H e do 7Li em função da temperatura e da viscosidade, com objetivo de estudar a mobilidade da cadeia polimérica e dos íons lítio. Os valores para o tempo de correlação, obtidos dos dados de relaxação, mostram que a mobilidade da cadeia polimérica e dos íons lítio são comparáveis aos encontrados em outros eletrólitos poliméricos similares Os sistemas vítreos estudados foram o vidro fosfato In(PO3)3 e o sistema binário (1-x)In(PO3)3 - xBaF2, com o objetivo de determinar o grau de polimerização da cadeia de fosfatos. Os estudos do 31P MAS RMN para diferentes tempos de fusão dos vidros fosfatos, permitiram verificar que presença da água reduz o comprimento da cadeia pela hidrólise das ligações P-O-P produzindo duas cadeias com grupos terminais -P-OH. A adição do BaF2 no vidro fosfato, reduz o comprimento da cadeia de fosfatos formando oxigênio não ponteante. Altas concentrações do BaF2 causa a depolimerização da cadeia de fosfatos formando grupos pirofosfatos (Q1) e grupos ortofosfatos (Q0). / In this work we report the study of new polymer electrolytes and phosphate glasses using Nuclear Magnetic Resonance (NMR) technique. The polymer electrolytes studied were polyester (glycol ethylene / citric acid) and films formed by hydroxyethylcelluloses (HEC), poly(ethy1ene oxide) and poly(propy1ene oxide) diisocyanates, both with lithium salt. To study the mobility of polymer chains and lithium ions in the polymer electrolytes, measurements of the temperature and viscosity dependence of 1H e do 7Li lineshape and spin-lattice relaxation rate were realized. The correlation times obtained from relaxation data, show that the mobility of polymer chains and lithium ions are comparable to those found in other similar polymer electrolytes. The degree of polymerization of the phosphate chain was studied in phosphate glass In(PO3)3 and in the binary system(1-x)In(PO3)3 - xBaF2. The 31P MAS NMR for different melting times, indicate that the water reduces the chain length by hydrolyzing P-O-P bonds to produce two separated chains, terminated by -P-OH groups. The addition of BaF2 in the phosphate glass, reduces the phosphate chain length by forming non-bridging oxygen ions. High concentration of BaF2 causes depolymerization of the phosphate chain to create pyrophosphate groups (Q1) and orthophosphate groups (Q0).

Este trabalho apresenta um estudo sobre a influência de nanopartículas de prata nas propriedades ópticas de vidros de telureto dopados com íons de terras raras para aplicações em fotônica. Foram estudados três sistemas vítreos diferentes, TeO2-ZnO (B1), TeO2-PbO-GeO2 (T1) e TeO2-GeO2-BaO-Nb2O5 (Q3), todos preparados com óxidos de Itérbio (Yb2O3), Praseodímio (Pr2O3) e Érbio (Er2O3), além do reagente Nitrato de Prata (AgNO3), precursor das nanopartículas. Estes vidros possuem uma larga região de transmissão (350-6500 nm), boa estabilidade química, resistências mecânica e térmica, baixa energia de fônon (em torno de 700 cm-1) e alto índice de refração (~ 2,0). Através de medidas de absorção óptica foi observada a incorporação dos íons de terras-raras na forma trivalente, responsável pelo fenômeno de luminescência nos vidros. Para comprovar a presença das nanopartículas foram realizadas análises de Microscopia Eletrônica de Transmissão. As análises de microscopia eletrônica de transmissão permitiram observar o tamanho e o formato das nanopartículas formadas. A composição das nanopartículas foi obtida através da técnica de difração de elétrons realizada durante os ensaios de microscopia eletrônica de transmissão. As nanopartículas obtidas nos sistemas vítreos estudados apresentaram-se na forma metálica e cristalina, com tamanho médio variando entre 3 nm e 12 nm. Para o sistema B1 preparado com Yb2O3 foram feitas as medidas da luminescência cooperativa das amostras vítreas e de fibras nanoestruturadas, e estudada a interferência das nanopartículas. Para os sistemas preparados com Pr2O3 e AgNO3 e com Er2O3 e AgNO3 foram estudadas as interferências das nanopartículas nas emissões. Os resultados mais relevantes foram obtidos para o sistema T1, preparado com Pr2O3, para o qual foi observado aumento significativo da intensidade de emissão, de aproximadamente 100 %, na presença das nanopartículas quando comparadas as amostras tratadas por 1 h e 17 h. A diminuição da luminescência, observada em algumas amostras, é atribuída ao fato de as nanopartículas estarem situadas, em relação aos íons de terras-raras, a distâncias inferiores a 5 nm. Os resultados obtidos demonstram que as emissões de íons de terras-raras mais afetadas são as que se encontram mais próximas da banda de absorção do plasmon das nanopartículas. / This work presents a study about the influence of silver nanoparticles in the optical properties of tellurite glasses doped with rare-earths ions for photonic applications. Three different glassy systems were study, TeO2-ZnO (B1), TeO2-PbOGeO2 (T1) and TeO2-GeO2-BaO-Nb2O5 (Q3), all of them prepared with Ytterbium (Yb2O3), Praseodymium (Pr2O3) and Erbium (Er2O3) oxides, and the Silver Nitrate reagent (AgNO3), the nanoparticles precursor. These glasses have a large transmission window (350-6500 nm), chemical stability, mechanical and thermal resistance, low phonon energy (around 700 cm-1) and high refractive index (~2,0). The optical absorption measurement showed the incorporation of rareearths ions in the trivalent form, responsible for the luminescence phenomenon in the glasses. In order to prove the presence of nanoparticles, analyses of Transmission Electron Microscopy (TEM) were performed. These analyses allowed the observation of the size and of the shape of the formed nanoparticles. The composition of the nanoparticles was obtained by the electron diffraction technique performed during the transmission electron microscopy analyses. The nanoparticles obtained in the studied glassy systems presented themselves in metallic and crystalline form, with average size varying between 3 nm and 12 nm. For the B1 system doped with Yb2O3, the cooperative luminescence analyses from the glassy samples and the nanostructured fiber glasses were performed, and the interference of the nanoparticles was studied. For the systems doped with Pr2O3 and AgNO3 and with Er2O3 and AgNO3, it was studied the interference of the nanoparticles on the emissions. The most relevant results were obtained for the T1 system, prepared with Pr2O3, which presented significant enhancement of luminescence, nearly 100 %, in the presence of nanoparticles when compared to the samples heat treated for 1 h and 17 h. The decrease of the luminescence, observed for some samples, is attributed to the fact that the distance between the nanoparticles and the rare-earth ions is smaller than 5 nm. The results obtained show that the rare-earth emissions, that are more influenced, are those whose wavelengths are nearer of the plasmon resonance band of the nanoparticles.

"Apr 2002." / The numerals in title is subscript. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

Investigamos analiticamente as propriedades estatísticas dos mínimos locais (estados metaestáveis) de vidros de spin de Ising com interações de p-spins na presença de um campo magnético h. O número médio de mínimos, assim como a sobreposição típica entre pares de mínimos idênticos são calculados para qualquer valor de p. Para p &#62 2 e h pequeno mostramos que a sobreposição típica qt é uma função descontínua da energia. O tamanho na descontinuidade em qt cresce com p e decresce com h, indo a zero para valores finitos do campo magnético [1]. Investigamos as correções ao alcance infinito para o caso em que h = 0 e encontramos que o número de estados metaestáveis aumenta quando o efeito de conectividade finita é considerado e esse aumento torna-se mais pronunciado à medida que p aumenta [2]. Ainda, estudamos a termodinâmica deste modelo utilizando o método das réplicas. Demos ênfase à análise da transição entre os regimes de simetria de réplicas e o primeiro passo de quebra de simetria de réplicas. Em particular, derivamos condições analíticas para o início da transição contínua, assim como para a localização do ponto tricrítico onde a transição entre os dois regimes torna-se descontínua [3]. Como aplicação de interações de ordem alta em sistemas de spins contínuos, estudamos analiticamente as propriedades estatísticas de um ecossistema composto de N espécies interagindo através de interações Gaussianas aleatórias de ordem p &#8805 2 e auto-interações determinísticas u &#8805 0. Para o caso u &#8800 0, o aumento na ordem das interações faz com que o sistema se torne mais cooperativo. Para p &#62 2 há um limite inferior para a concentração de espécies sobreviventes, prevenindo a existência de espécies raras e, conseqüentemente, aumentando a robustez do ecossistema contra perturbações externas [4]. / The statistical properties of the local optima (metastable states) of the infinite range Ising spin glass with p-spin interactions in the presence of an external magnetic field h are investigated analytically. The average number of optima as well as the typical overlap between pairs of identical optima are calculated for general p. For p &#62 2 and small h we show that the typical overlap qt is a discontinuous function of the energy. The size of the jump in qt increases with p and decreases with h, vanishing at finite values of the magnetic field [1]. We study the corrections to the infinite range model for h = 0 and find that the number of local optima increases as the effect of the finite connectivity is considered, and that this increase becomes more pronounced for large p [2]. Furthermore, we study analytically the thermodynamics of this model using the replica method, giving emphasis to the analysis of the transition between the replica symmetric and the one-step of replica symmetry breaking regimes. In particular, we derive analytical conditions for the onset of the continuous transition, as well as for the location of the tricritical point at which the transition between those two regimes becomes discontinuous [3]. As an application of high-order interactions in systems of continuous spins, we study the statistical properties of an ecosystem composed of N species interacting via random Gaussian interactions of order p &#8805 2, and deterministic self-interactions u &#8805 0. For nonzero u the increase of the order of the interactions makes the system more cooperative. We find that for p &#62 2 there is a threshold value which gives a lower bound to the concentration of the surviving species, preventing then the existence of rare species and, consequently, increasing the robustness of the ecosystem to external perturbations [4].

Orientador: Keizo Yukimitu / Banca: Antonio Medina Neto / Banca: Elso Drigo Filho / Resumo: Neste trabalho foram estudadas as propriedades ópticas de vidros teluretos do sistema (20-x)Li2O-80TeO2-xTiO2 com x = 0, 5, 10 e 15 mol%. Foram preparadas amostras para cada uma das composições através do convencional método de "meltquenting". Medimos, para cada amostra, o espectro de infravermelho e o espectro na faixa do ultravioleta-visível. Também obtemos os valores de índice de refração de cada amostra para diversos comprimentos de onda na faixa do visível. Para tanto, utilizamos um interferômetro de Michelson-Morley modificado. Medidas de densidade foram feitas utilizando-se o convencional método de Arquimedes. Por fim, foram feitas medidas do coeficiente térmico do caminho óptico através da interferometria. A análise estrutural foi feita através do espectro de infravermelho. Pode-se observar a tendência à formação de pirâmides trigonais em substituição às bipirâmides (encontradas no TeO2 cristalino) quando aumentamos a porcentagem de óxido de lítio. Uma análise qualitativa da absorção na faixa de interesse em comunicações ópticas (~1500 nm) foi feita através do espectro de infravermelho próximo, mostrando que nesta faixa temos a predominância do espalhamento Rayleigh, com o coeficiente de absorção proporcional a λ-4. Usando os dados da espectroscopia na faixa ultravioleta-visível foi possível observar a mudança das freqüências de corte para cada composição e ainda calcular a energia de gap e a energia de cauda de Urbach. Através do modelo clássico de osciladores harmônicos forçados de Wemple, os resultados de índice de refração foram interpretados. Buscou-se ainda relacionar as mudanças observadas para os valores medidos para cada composição com possíveis mudanças estruturais. Concluímos, usando as considerações de Wemple, que o aumento... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In this work had been studied tellurite glasses's the optic properties of the system (20-x) Li2O-80TeO2-xTiO2 with x = 0, 5, 10 and 15 mol%. Samples for each one of the compositions through the conventional method of melt-quenting had been prepared. We measure, for each sample, the infra-red ray specter and the specter in the band of the ultraviolet-visible one. Also we get the values of refractive index of each sample for diverse wave lengths in the visible band. For in such a way, we use a modified interferometer of Michelson-Morley. Measures of density had been made using the conventional method of Archimedes. Finally, they had been made measured of the thermal coefficient of the optic way through the interferometry. The structural analysis was made through the infra-red ray specter. The trend to the formation of trigonais pyramids in substitution to the bipyramids can be observed (found in the crystalline TeO2) when increases the lithium oxide percentage. A qualitative analysis of the absorption in the band of interest in optic communications (~1500 nm) was made through the infra-red ray specter, showing that in this band we have the predominance of the Rayleigh scattering, with the coefficient of absorption proportional to λ-4. Using the data of the spectroscopy in the ultraviolet-visible band to each composition was possible to observe the change of the cut-off frequencies and still to calculate the energy of gap and the energy of Urbach. Through the classic model of forced harmonic oscillators of Wemple, the results of refractive index had been interpreted. We still searched to relate the changes observed for the values measured for each composition with possible structural changes. We conclude, using the considerations of Wemple, that the increase for the values of... (Complete abstract click electronic access below) / Mestre

Dans cette thèse, on a étudié les effets provoqués par des changements de composition et de température sur la structure et les propriétés des verres des systèmes TiO₂-SiO₂ et Na₂O-TiO₂-SiO₂. On a également examiné la réponse des verres du système Na₂O-TiO₂-SiO₂ à la déformation plastique. On a fabriqué des verres (x)TiO₂-(1-x)SiO₂ par le procédé sol-gel avec des compositions de 0 ≤ x ≤ 10 mol%, puis on les a comparés avec des verres commerciaux fabriqués par la déposition provoquée par l'hydrolyse à la flamme x = 0 ; 5,4 ; et 8,3 mol%. On a fabriqué des verres (x) Na₂O - (y) TiO₂ - (1-x-y) SiO₂ avec x = 10, 15, 20, et 25 mol% et y = 4, 7, and 10 mol% par trempage depuis l'état fondu. On a mesuré la densité des verres en utilisant le principe d'Archimède et on a mesuré l'indice de réfraction des verres par prisme coupleur. On a évalué la température de transition vitreuse des verres Na₂O-TiO₂-SiO₂ par analyse thermique différentielle. On a étudié la structure et les modules d'élasticité par spectroscopie Raman et par diffusion Brillouin, respectivement, à température ambiante et in situ jusqu'à 1 200 °C pour les verres TiO₂-SiO₂ et jusqu'à 800 °C pour les verres Na₂O-TiO₂-SiO₂. On a constaté que le module de Young des verres TiO₂-SiO₂ a diminué de 72GPa à 66 GPa avec l'addition de 8,3 mol% TiO₂, et que le module de Young des verres 10 Na₂O - (0-10) TiO₂-SiO₂ a augmenté de 65 GPa à 73 GPa avec l'addition de 10 mol% TiO₂. On a vu que l'addition de TiO₂ aux verres TiO₂-SiO₂ a décalé les sommets du spectre Raman de 460, 490, et 600 cm-1 aux fréquences plus basses, ce qui suggère un réseau structural plus ouverte et flexible ; et que l'addition de TiO₂ aux verres Na₂O-TiO₂-SiO₂ a décalé les sommets du spectre Raman 720, 800, et 840 cm-1 aux fréquences plus élevées, ce qui suggère une réduction de volume libre et un réseau structural plus rigide. L'addition de TiO₂ n'a que peu d'effet sur la réponse thermique des modules élastiques des deux systèmes, mais elle diminue l'expansion thermique et augmente les décalages de fréquences des sommets Raman de 950 and 1100 cm-1 du système TiO₂-SiO₂, alors que l'expansion thermique du système Na₂O-TiO₂-SiO₂ augmente avec les premières additions de TiO₂ et puis reste constante. Les changements de structure et de propriétés liés à la composition sont examinés, et des modèles structuraux sont proposés. La réduction d'expansion thermique et des modules d'élasticité des verres TiO₂-SiO₂ se produit par la promotion des rotations coopératives inter-tétraèdres facilitées par les liaisons Ti-O plus longues et plus faibles. L'augmentation des modules d'élasticité des verres Na₂O-TiO₂-SiO₂ est due à la formation de petits groupes avec des concentrations élevées de Na et Ti, produit par l'adoption de Ti d'une coordination quintuple d'une géométrie de pyramide à base carrée. Ces petites « globules » protègent le réseau silice des oxygènes non-pontants tout en augmentant la densité des liaisons du verre. On a étudié la réponse des verres Na₂O-TiO₂-SiO₂ au dommage mécanique et la déformation plastique par des essais d'indentation Vickers de charges de 10 mN to 49 N. La dureté de fracture a été mesurée sur éprouvette préfissurée sur une seule face (méthode SEPB). On a examiné les volumes de déformation permanente auprès des indentations Vickers par microscopie à force atomique. Les indentations Vickers ont changé d'un mélange de radial/médian et des fissures coniques à un mélange de radial/médian et des fissures latérales, suivant l'augmentation du coefficient de Poisson. Avec la croissance du coefficient de Poisson, la dureté de verre diminue de 5,5 GPa à 4,5 GPa ; la longueur moyenne de fissure radial/médian double, à peu près ; et la dureté de fracture reste constante. Le volume de verre déformé par l'écoulement de cisaillement augmente petit à petit avec l'augmentation du coefficient de Poisson et devient plus grand que le volume densifié à ν =0,237. / The responses of structure and properties to composition and temperature have been investigated for glasses in TiO₂-SiO₂ and Na₂O-TiO₂-SiO₂ systems. Additionally, the response of Na₂O-TiO₂-SiO₂ glasses to plastic deformation has been studied. (x)TiO₂-(1-x)SiO₂ glasses were prepared through the sol-gel process with compositions 0 ≤ x ≤ 10 mol% and compared to commercial glasses prepared through flame hydrolysis deposition with x = 0, 5.4, and 8.3 mol%. (x) Na₂O - (y) TiO₂ - (1-x-y) SiO₂ glasses were prepared with x = 10, 15, 20, and 25 mol% and y = 4, 7, and 10 mol% through a melt-quench process. Density and index of refraction of glasses was measured through the Archimedes's method and using a prism coupler, respectively. The glass transition temperature of Na₂O-TiO₂-SiO₂ glasses was measured through differential thermal analysis. The structure and elastic moduli have been studied through Raman spectroscopy and Brillouin light scattering, respectively, at room temperature and in-situ up to 1200 °C for TiO₂-SiO₂ glasses and up to 800 °C for Na₂O-TiO₂-SiO₂ glasses. Young's modulus was observed to decrease from 72 GPa to 66 GPa with the addition of 8.3 mol% TiO₂ in TiO₂-SiO₂ glasses and to increase from 65 GPa to 73 GPa with the addition of 10 mol% TiO₂ in 10 Na₂O - (0-10) TiO₂-SiO₂ glasses. The addition of TiO₂ was observed to shift the 460, 490, and 600 cm-1 Raman peaks to lower frequencies in TiO₂-SiO₂ glasses, suggesting a more open and flexible network, and the 720, 800, and 840 cm-1 Raman peaks to higher frequencies in Na₂O-TiO₂-SiO₂ glasses, suggesting a lower free volume and stiffer network. The addition of TiO₂ has little effect on the temperature response of the elastic moduli in either system, but decreases the thermal expansion and increases the frequency shifts in the 950 and 1100 cm-1 Raman peaks in the TiO₂-SiO₂ system while the thermal expansion increases with initial additions of TiO₂ and then remains constant in the Na₂O-TiO₂-SiO₂ system. Changes in structure and property with composition have been discussed, and structural models were proposed. The reduction of thermal expansion and elastic moduli in TiO₂-SiO₂ glasses occurs through the promotion of cooperative, inter-tetrahedral rotations facilitated by the longer and weaker Ti-O bonds. The increase in elastic moduli in the Na₂O-TiO₂-SiO₂ glasses occurs through the formation of small clusters with local, relatively high Ti and Na concentrations, promoted by Ti adopting a five-fold coordination in a square-pyramidal geometry. These clusters work to shield the silica network from non-bridging oxygens from the presence of Na while simultaneously increasing the volume bond density of the glass. For Na₂O-TiO₂-SiO₂ glasses, the response to mechanical damage and plastic deformation has been examined through Vickers indentation experiments at loads from 10 mN to 49 N. Fracture toughness was measured through the single-edge precracked beam method. The permanent deformation volumes around Vickers indents were investigated through atomic force microscopy. Critical loads for crack initiation and cracking patterns were systematically investigated and correlated with the elastic properties of glass. Vickers indents were observed to change from a mixture of radial/median and cone cracks to radial/median and lateral cracks as Poisson's ratio increases. As Poisson's ratio increases hardness decreases from 5.5 GPa to 4.5 GPa, the average radial/median crack length roughly doubles, and fracture toughness remains constant. A minimum in the critical crack initiation load was observed at ν = 0.21-0.22. The volume of glass deformed through shear flow increases gradually with increasing Poisson's ratio, becomes larger than the densified volume at ν =0.237.

Vidros condutores à base de boratos, silicatos e sílico-sulfatos de íons de metais alcalinos foram preparados a partir da mistura apropriada de pós de óxidos, carbonatos e sulfatos, Eles foram produzidos a partir da fusão e resfriamento rápido em um forno de carbeto de silício de ate 1400ºC. Estes materiais foram analisados pelas técnicas de condutividade em corrente contínua (CC) e por Espectroscopia de Impedância (EI) nas caracterizações elétricas, por Difração de Raios X (DRX) para análise estrutural, Absorção Ótica (AO) par verificar a transmitância e pelas técnicas de Espectroscopia de Emissão de Chama (EEC) e Retroespalhamento de Rutherford (RBS) para identificar as composições. Os difratogramas de Raios X mostraram que se tratam de sólidos amorfos. Os espectros de AO mostraram forte absorção na região do ultravioleta e completa transparência para a luz visível. As técnicas de EEC e RBS indicaram perdas pequenas de óxidos de sódio e lítio porem grandes de sulfatos. Os principais resultados mostraram: a maior condutividade entre os materiais estudados, de 2,3×10-4S/cm para o vidro 53,4Na2O·6,6Na2SO4·40,0SiO2 mol%, caracterizando-o como um condutor iônico rápido (FIC-Fast Ion Conductor); concordância nos valores de condutividade em CC e CA, e uma melhor caracterização das propriedades dielétricas, como capacitância C, freqüência de relaxação f0 e ângulo de descentralização Fi. Alem do comportamento do tipo Arrhenius em todas as amostras foi identificada também uma não-homogeneidade estrutural através de um segundo semicírculo por EI. Por fim, aplicando tensões de até 1kV foram verificados o implante de prata em dois vidros através da técnica de RBS. / Conducting glasses based on borates, silicates and silica-sulfates of alkali metals have been prepared from an appropriate mixture of powder of oxides, carbonates and sulfates. They were produced by fusion in a silicon carbide furnace up to 1400ºC and then by fast cooling. These materials have been analyzed with techniques of DC conductivity and Impedance Spectroscopy (IS) for electrical characterizations, by X Ray Diffraction (XRD) for structural analysis, Optical Absorption (OA) to verify the transmittance characteristics and by techniques of Flame Emission Spectroscopy (FES) and Rutherford Backscattering (RBS) to identify their compositions. The X Rays difractrograms have shown that they are amorphous solids. The AO spectra showed strong absorption in UV region and a full transparency for visible light. The FES and RBS techniques indicated little loss of sodium and lithium oxides, however greater loss of sulfates. The main results shown that: among all the samples the largest conductivity, of 2.3×10-4S/cm at 150ºC was found for the glass 53.4Na2O·6.6Na2SO4·40.0SiO2 mol%, characteristic of a FIC (FIC-Fast Ion Conductor) system; also a concordance of DC and AC conductivity values, and a better characterization of dielectrical properties, such as capacitance C, relaxation frequency f0 and depression angle Fi. Besides the Arrhenius in all the samples a structural non-homogeneity was found in a second semicircle by IS. Lastly a successful Ag implant on two glasses was certified by the RBS technique, by application of voltages up to 1kV.