No description available.

No description available.

Two systems of glasses have been studied: soda-lime-silica and alkali borate glasses. Vitreous boron oxide was included as a standard for comparison with alkali borates. Silica and irradiated vitreous silica were included for low Q diffraction studies as comparison with previous results.

This thesis begins with a molecular dynamics simulation of magnesium silicate glasses. Although an extensive literature addresses various techniques in studying the structure of x(MgO).(100-x)(Si02) glasses, this study has discussed in detail the environment of Mg atom and the presence of non-network oxygen atoms in these glasses. The average coordination number of magnesium by oxygen was increased from 4.5 ± 0.3 to 5.0 ± 0.3 by increasing x from 50 to 67. There are - 5% non-network oxygen for x=50 and the proportion increases up to 16% for x=67. Moreover, this study reported slight changes in Si-O and Mg-O environments; however, the changes in 0-0 correlations were noticeable in magnesium silicate glasses at pressures up to 9GPa. Most of this thesis presents studies of the structure of a range of important iron phosphate glasses. The ,effect of the, different oxidation states of Fe in xFeO.(100-x)P20s glasses and xFe203~(100-X) P20S glasses has been investigated by building several models using molecular dynamics simulation. The short range order in these glass models is realistic, with a well-defined phosphate network, and both Fe2+ and Fe3+ ions were found to have a typical c~ordination of - 4.5 in 40FeO and 40F~03 glasses. This thesis also includes modelling of multi-component phosphate glasses such as (P20S)sO(CaO)3o(Na20ho glass and sodium borophosphate glasses containing niobium. Both Ca and Na play the role of modifier in the (P20S)SO(CaO)3o(Na20)20 glass model with estimated .;.' coordination numbers of 5 and 6 respectively. Sodium borophosphate glasses containing niobium models confirmed that Nb06 octahedra prefer to be isolated at low Nb content, and connected to other Nb06 at higher Nb content. A series of techniques was used to investigate the structure of sodium iron phosphate glasses prepared by melt quenching: X-ray and neutron diffraction, X- ray absorption spectroscopy, Fourier transform infrared spectroscopy and Mossbauer spectroscopy. The environment of both Fe and Na and their effect on IV • the chemical durability in phosphate glasses have been investigated. This study proposed that Fe-O coordination number in these glasses is in the range of 4.8- 5.7 with a trend of decreasing the coordination number with increasing iron content. Whereas the Na coordination number of approx. 5 remains the same through different compositions. In depth structural studies have been carried out on amorphous FeP04 prepared by two different methods, and on amorphous LiFeP04" prepared by electrochemical insertion of Li. The local environment of Fe in these samples was investigated using Mossbauer spectroscopy and X-ray absorption spectroscopy. X-ray and neutron diffraction "and transmission electron microscopy have been applied to elucidate the first complete structural study of these materials. The Fe environment in amorphous FeP04 was found to be similar to that in quartz FeP04 where every Fe is surrounded by four oxygen' atoms. However, the Fe environment in amorphous LiFeP04 is affected by the appearance of Fe metal in this sample as a consequence of Li insertion. Small- angle scattering measurements confirmed the presence of nm-scale internal structure in the amorphous FeP04 prepared by thermal decomposition and in amorphous LiFeP04.

No description available.

Float glass is widely used in architecture and in the automotive industry. During the float process tin diffuses into and reacts with the glass melt. The presence of tin in the glass surface region causes mismatch in thermoelastic properties between the bulk and the surface. This, in turn, can lead to wrinkling of the surface after the glass is subject to a toughening heat treatment. This project involves trying to understand the diffusion and reaction mechanisms that contribute to this phenomenon. A set of partial differential equations describing the important reaction-diffusion mechanisms has been proposed. This mathematical model is based on 3 redox reactions in the glass melt. 6 diffusing and reacting species have been considered, which comprise 3 redox couples, namely stannous and stannic tin, ferrous and ferric iron, and hydrogen atoms and ions. Using guessed parameters, the computer simulation shows the most striking feature of the tin depth profile - the tin hump, which is observed experimentally by Secondary Ion Mass Spectrometry (SIMS) and Electron Probe Micro-Analysis (EPMA). It can be observed from the simulations that stannous tin diffusing into the glass is oxidised to stannic tin by ferric iron. The tin hump is due to the immobile stannic tin. The shape and location of the hump can be influenced by the float bath atmosphere and the oxidising species in the glass. These features are in agreement with experimental findings. The simulation also reveals that the tin hump forming process is a dynamic process. The Sn(IV) forms and converts back to Sn(II) simultaneously as the hump moves in the glass melt. However, an inverse method has not been found to recover the parameters of the mathematical model from SIMS data. This is due to SIMS's data being only qualitative, as well as the complexity of the model.

De nos jours, les dosimètres existants sont insuffisants pour la surveillance et le contrôle des rayonnements ionisants dans toutes les configurations et surtout en environnement sévère. En dosimétrie optique, les systèmes fibrés permettent de répondre en temps réel à des débits de dose relativement faibles, de réaliser des mesures dans des endroits difficiles d’accès, avec une résolution spatiale intéressante. Ce travail a consisté en l’étude de verres de silice élaborés par voie sol-gel et dopés par du cuivre ou du cérium ionique, en vue de les utiliser dans un dispositif dosimétrique. Ces verres ont été caractérisés par différentes techniques spectroscopiques avant et après irradiations. Dans le cas des verres dopés Cu, après irradiation X ou γ (1 MGy), les défauts HC1, HC2 et E’ ont été identifiés. Quant aux verres dopés Ce, ils sont plus résistants et restent incolores, même après une dose de 8,8 MGy sous X. Des mesures de la réponse optique des échantillons sous rayons X ont été réalisées grâce à un dispositif fibré. Concernant les verres dopés Cu, la sensibilité en radioluminescence (RL) couvre la gamme de débits de doses allant de 0,25 à au moins 800 mGy/s et la linéarité de la luminescence optiquement stimulée (OSL) a été démontrée entre 40 mGy et 200 Gy. Les verres dopés Ce sont plus performants en termes de linéarité. En effet, les signaux de RL et d’OSL sont linéaires jusqu’à 1,2 Gy/s et 500 Gy respectivement pour ce dopant. Un fading de l’OSL à court-terme a été mis en évidence avant stabilisation du signal. Les résultats obtenus montrent que ces verres dopés présentent un grand intérêt pour la dosimétrie fibrée de radiations ionisantes. / Nowadays, existing dosimeters are insufficient for monitoring and control of ionizing radiation in all configurations and especially in severe environments. In optical dosimetry, fiber systems allow to provide a real-time response to relatively low dose rates, making possible some measurements in hard-to-reach places with interesting spatial resolution. This work consisted in the study of sol-gel silica glasses doped with ionic copper or cerium, with the aim of using them in a dosimetry device. These glasses have been characterized by different spectroscopic techniques before and after irradiations. In the case of Cu-doped glasses, after X or γ irradiation (1 MGy), the defects HC1, HC2 and E' have been identified. As for Ce-doped glasses, they are more resistant and remain colorless, even after a dose of 8.8 MGy under X. Measurements of the optical response from the samples under X-rays were carried out using a fibered device. For Cu-doped glasses, radioluminescence (RL) sensitivity covers dose rates ranging from 0.25 to at least 800 mGy/s and the linearity of optically stimulated luminescence (OSL) has been demonstrated in the range 40 mGy-200 Gy. Ce-doped glasses are more efficient in terms of linearity. Indeed, for this dopant, RL and OSL signals are linear up to 1.2 Gy/s and 500 Gy, respectively. Short-term OSL fading was observed before stabilization of the signal. The obtained results show that these doped glasses are of great interest for fibered dosimetry of ionizing radiations.

Les verres de silice dopés par le Bismuth sont très prometteurs en raison de leurs applications potentielles en termes de lasers à fibres et d’amplificateurs optiques large bande destinés aux télécommunications optiques. Toutefois, la nature des centres optiquement actifs dans de tels verres demeure un sujet d’intenses débats. Les méthodes spectroscopiques magnéto-optiques sont des outils puissants pour l’étude des centres paramagnétiques au sein de la matière condensée. Dans ce travail de thèse, les techniques de dichroïsme circulaire magnétique, de polarisation circulaire magnétique de l'émission et de résonance magnétique détectée optiquement ont été mises en œuvre pour étudier les verres dopés par le Bismuth. En association avec les méthodes spectroscopiques conventionnelles, nous avons montré la coexistence d’au moins deux types de centres optiquement actifs dans des verres de silice dopés par le Bismuth sans autres co-dopants et de trois types dans un verre aluminosilicate dopé par la Bismuth. L’analyse des données expérimentales a révélé que tous les centres proviennent de systèmes ayant un nombre pair d’électrons (ou de trous). Deux centres ont été identifiés aux ions Bi+ et aux défauts du réseau vitreux qui interagissent via des processus de transfert d’énergie. Le troisième centre est attribué aux clusters d’ions Bismuth et a été observé seulement dans des verres aluminosilicates fortement dopés. Pour la première fois, nous avons montré expérimentalement que l’effet laser dans le proche infrarouge est due à une transition interdite à partir du premier état excité d’un défaut du réseau vitreux. / Bismuth-doped silica glasses are interesting due to the promising applications in fiber lasers and amplifiers for the communication purposes. Unfortunately, the nature of the optical active centre(s) in such glasses is still a subject of intense debuts.Magneto-optical methods of spectroscopy are very powerful tools for the investigation of paramagnetic centres in condensed matters. In this thesis, the magnetic circular dichroism, magnetic circular polarization of luminescence and optically detected magnetic resonance techniques were implemented to investigate Bi-doped silica glasses. Together with the methods of the conventional optical spectroscopy, we demonstrate the coexistence of at least two types of optical centres in a Bi-doped silica glass without other co-dopants and three types in a Bi-doped aluminosilicate glass. The analysis of experimental data revealed that all centres originate from systems with an even number of electrons (or holes). Two centres were identified as Bi+ ion and some defect in the glass network that interact via the energy transfer processes. The third centre is assigned to the clusters of Bi ions and it was observed only in the highly doped aluminosilicate sample. For the first time, we showed experimentally that the lasing related near-infrared luminescence is caused by a forbidden transition from the first excited state of the defect centre.

L'objectif de cette thèse est de développer et étudier des dépôts d’oxydes métalliques minces à base de Silicium et d’Etain par un plasma froid à pression atmosphérique, afin de conférer des propriétés spécifiques à des substrats en verre et afin de trouver des alternatives écologiques à certains procédés actuellement utilisés par les verriers. Cette recherche se divise en trois parties: la première partie consiste à déposer à partir d’Hexaméthyldisilane et d’Hexaméthyldisiloxane des couches minces de SiO2/SiOxCy sur du verre sodocalcique afin d’améliorer sa résistance à la rupture. La seconde partie consiste à déposer une couche mince de SnO2 sur du verre fluorosilicate à partir de Tetrabutylétain et d’Oxyde de Tributylétain pour trouver une alternative écologique au dépôt à chaud actuellement utilisé. Enfin, ces dépôts à base de silicium et d’étain seront utilisés dans la troisième partie afin de lutter contre le phénomène de sudation de surface des verres fluorosilicates. En parallèle, les propriétés physicochimiques de ces couches minces seront caractérisées avec des technologies avancées afin de les optimiser. / The objective of this thesis is to develop and characterize the deposition of thin metal oxides based on silicon and tin by an atmospheric pressure cold plasma to improve properties of glass materials and find an ecological alternative to existing processes. This research is divided into three main parts: the first part consists in depositing from Hexamethyldisilan and Hexamethyldisiloxan thin films of SiO2/SiOxCy on soda-lime glass to improve its mechanical strength. The second part consists in depositing a thin layer of SnO2 on fluorosilicate glass from Tetrabutyltin and Tributyltin Oxide to develop an environmental friendly alternative to the current chemical vapor deposition process used in glass industry. Finally, the silicium and tin based deposits obtained are used in the third part to stop corrosion surface of fluorosilicate glasses. In parallel, the physicochemical properties of these thin films will be characterized with advanced technologies in order to optimize the deposits.

Ce travail a pour objectif principal d'adapter l'opalisation des verres sodocalciques destinés au flaconnage, à la technologie existante de coloration en feeder. Les résultats obtenus amènent à proposer des alternatives aux particules opacifiantes usuelles résultant de l'introduction de cristaux de fluorures, dangereux pour leur environnement. L'opalisation dans un verre sodocalcique induite par l'apport de phosphore, résulte de la précipitation du phosphate mixte NaCaPO4. Cependant, la formation de cette phase nécessite des traitements thermiques difficilement adaptables à la technologie de coloration en feeder. La voie finalement envisagée est celle des oxydes à faible solubilité SnO2, ZrO2 et ZrSiO4. L'oxyde d'étain a fait l'objet d'approfondissements spécifiques dans la mesure où sa limite de solubilité est la plus faible. L'influence de la composition des verres sodocalciques est abordée et les conséquences du caractère multivalent de l'élément Sn sont évaluées avec l'appui de mesures in-situ par des méthodes électrochimiques. Des produits opacifiants contenant SnO2 sont finalement proposés, répondant au cahier des charges et n'introduisant pas de fluorures. Les compositions de ces produits, sous formes de frittes vitreuses, ainsi que les paramètres semi-industriels principaux sont optimisés suite à deux plans d'expériences. / The main goal of the present work is to achieve hollow-ware soda-lime glass opalization, through the forehearth color (FHC) technology. The results are suggesting two solutions to get rid of the usual opacifying particles: fluorides crystals. These are known to be dangerous and highly corrosive. Soda-lime glass opalization, induced by phosphorus addition, consists in NaCaPO4 precipitation. However, this phase appears only after specific heat treatments, which are found to be hardly compatible with the FHC technology. Low solubility oxides SnO2, ZrO2 and ZrSiO4, are finally chosen as a second option for opalization. Tin oxide is more precisely studied, as it has the lowest solubility limit. The influence of glass composition on the oxides solubilization is investigated. Tin multivalent property is also characterized using in situ electrochemical methods. Opacifying compounds (glass frits) containing SnO2 are finally developed, in agreement with all industrial requirements and avoiding the use of fluorides. Compositions of these compounds and semi-industrial process parameters are optimized with two distinct designs of experiments.