Dans cette thèse, des vitrocéramiques et composites à matrice verres ont été élaborés avec pour objectif principal d’étudier les interactions entre la fissure et les différentes inclusions. Dans un premier temps, la nucléation et la cristallisation volumique de sphérulites dans un verre du système BaO-Al2O3-SiO2 ont été étudiées. Puis, l’influence de la cristallisation sur l’élasticité, la dureté et la ténacité a été mesurée. Il est apparu une augmentation de ces propriétés suite à la cristallisation. Après dopage avec des oxydes de terres rares, le verre a été fonctionnalisé par l’apparition de cristaux phosphorescents à la surface du matériau. Dans un second temps, l’influence d’un différentiel de coefficient de Poisson (entre la matrice et les inclusions) sur la propagation d’une fissure a été étudiée. Pour cela des composites à particules et matrices vitreuses ont été élaborés par Spark Plasma Sintering (SPS) et étudiés par Double Cleavage Drilled Compression (DCDC). Il a été mis en lumière une déviation de la fissure quand cette dernière arrive à proximité des inclusions vitreuses dans le cas où le coefficient de Poisson de l’inclusion est inférieur à celui de la matrice. Une déviation de moindre importance a été observée dans le cas inverse. Enfin, des nanocomposites fonctionnalisés par des particules de magnétite (Fe3O4) et d’or ont été obtenus suite à un frittage SPS. Les propriétés apportées par ces particules ont permis le chauffage du matériau, respectivement, par induction et par irradiation laser. Dans le deuxième cas, après un traitement laser de 10 min, une cicatrisation partielle de fissures d’indentation a pu être observée. / In this thesis, glass-ceramics and glass matrix composites have been developed in order to study the interactions between the crack and the various inclusions. Firstly, the nucleation and volume crystallization of spherulites in a glass of the BaO-Al2O3-SiO2 system were studied. Then, the influence of crystallization on elasticity, hardness and toughness was measured. An increase of these properties due to crystallization was observed. After doping with rare earths oxides, the glass was functionalized by surface crystallization of phosphorescent crystals. Secondly, the influence of a Poisson’s ratio differential (between the matrix and inclusions) on the crack propagation was studied. For this purpose, glassy particulate glass matrix composites have been elaborated by Spark Plasma Sintering (SPS) and studied by Double Cleavage Drilled Compression (DCDC). A deviation of the crack in the vicinity of the glass inclusions has been identified in the case where the Poisson’s ratio of the inclusion is lower than the one of the matrix. In the opposite case, less important deviations were noticed. Finally, nanocomposites functionalized with magnetite (Fe3O4) and gold particles were obtained after a SPS treatment. The properties provided by these particles allowed the material to be heated, respectively, by induction and by laser irradiation. In the second case, after a 10 min laser treatment, a partial healing of indentation cracks could be observed.

O presente trabalho avaliou a formacao de tecido osseo ao redor de implantes osseointegraveis de titanio, apos realizacao de defeitos osseos, utilizando diferentes tipos de substitutos osseos. Foram utilizados 5 caes de raca indeterminada, os pre molares e molares mandibulares foram extraidos, passados 12 semanas, os caes foram submetidos a um novo procedimento cirurgico aonde foram realizadas as perfurações preconizados pelo fabricante dos implantes, o osso vestibular da mandibula foi desgastado ate que parte da perfuracao fosse exposta, os implantes entao foram colocados nas respectivas perfuracoes, ficando com 4 espiras expostas. Esses defeitos foram preenchidos aleatoriamente com Bioglass® 45S5, Biosilicato® , Osso autogeno, e sem nenhum material de preenchimento. 18 semanas depois da colocacao dos implantes os caes foram mortos e suas hemi-mandibulas contendo os implantes removidas e submetidas aos analises histologiaos e histomorfometricas, os dados obtidos foram submetidos ao teste de Kruskal-Wallis. A histologia dos 4 grupos estudados revelaram a presenca de tecido osseo maduro em contato com os implantes, porem sem ralacao direta com os vidros bioativos e osso autogeno. A porcentagem de contato osso implante, matriz ossea mineralizada ao redor da espira, e area de espelho, nao mostraram diferencas estatisticas significantes entre os 4 materiais testados. Os resultados indicam que a presenca de substitutos osseos nao interfere com a formacao ossea ao redor dos implantes nesse modelo experimental. E existe resposta tecidual muito semelhante entre o osso autogeno, Bioglass® 45S5 e Biosilicato. / The aim of the present study was to investigate the amount of bone formation on Ti implants in sites with intra-bony defects filled with different bone substitutes. Mandibular premolars and first molars were extracted from 5 dogs, and after 12 weeks 3 implants were bilaterally placed in sites with intra-bony defects and each implantation site randomly received the following treatment: Biosilicate®, Bioglass® 45S5, aoutologous bone or no treatment. At 18 weeks after implantation, the hemi-mandibles containing the implants were removed and processed for morphological and histomorphometric analysis. Data were submitted to Kruskal-Wallis and Fishers test. The histological sections of the 4 experimental groups exhibited mature bone tissue in contact with implants, but not related with bioactive glasses or autologous bone used. The percentage of bone-implant contact, mineralized bone matrix between implant threads, and mineralized bone matrix within mirror area in the treated or non-treated sites were not statistically different among the 4 experimental groups. These results indicates that the presence of the bone substitutes evaluated here did not interfere with bone formation on Ti implants in sites with intra-bony defects. In addition, tissue response to Biosilicate® was similar to that of Bioglass® 45S5 and autologous bone.

Research on the glass ceiling shows that women may encounter obstacles in their pursuit of high-level management positions. The purpose of this quantitative study was to test the explanatory style theoretical framework by examining relationships between women's glass ceiling beliefs, career advancement satisfaction, and quit intention and to determine whether satisfaction with career advancement opportunities mediated the relationship between glass ceilings beliefs and quit intention. Data were collected from 179 working women in the public or private sector and women who exited the public or private sector job market within the past 5 years via Web-based surveys. Glass ceiling beliefs were assessed using the Career Pathways Survey (CPS), career advancement satisfaction was assessed using the Career Satisfaction Measure, and quit intention was assessed using the Intention to Quit Scale and data were analyzed using multiple regression and correlational statistical techniques. Findings indicated significant relationships between the principal variables. Results also showed that career advancement satisfaction had a significant mediating effect on denial, resilience, and acceptance glass ceiling beliefs and quit intention. Findings may be used to help women understand how their glass ceiling beliefs and career satisfaction drivers influence their reaction to workplace events and may be used by employers to implement proactive retention strategies.

This PhD thesis presents structural investigations of amorphous inorganic materials: oxide and oxynitride glasses and mesoporous bioactive glasses (MBGs), by solid-state Nuclear Magnetic Resonance (NMR). Lanthanum oxide and oxynitride [La-Si-(Al)-O-(N)] glasses have a large number of potential applications due to their physical properties. In our work we have studied, compared to previous investigations, significantly expanded ranges of glass compositions (for oxynitride glasses, including samples of very high nitrogen content, up to 53 % out of the anions). We have estimated local environments of 29Si and 27Al structural units (their coordination, polymerization degree and number of N incorporated into tetrahedral units) in the materials. We have suggested a random Al/Si distribution along with almost uniform non-bridging oxygen atoms distribution in aluminosilicate glasses. Silicon nitride was used as precursor in the oxynitride glass synthesis. We studied both α- and β-modifications of silicon nitride, 15N-enriched, as well as fully (29Si, 15N)-enriched samples. We have shown that the linewidths of 15N NMR spectra are dominated by J(29Si-15N) coupling in 29Si315N4 sample. Mesoporous bioactive glasses in the CaO-SiO2-P2O5 system show superior bioactivity (the ability to form a hydroxycarbonate apatite layer on the glass surface when exposed to body fluids) compared to conventional bioactive glasses due to their large surface area and uniform pore-size distribution. Previous studies suggested a homogeneous cation distribution over the MBG samples on a 10−20 nm length-scale. From our results, on the other hand, we may conclude that Si and P is not intimately mixed. We propose a structural model, in which the pore walls of MBGs are composed of a silica network, and a phosphate phase is present as nanometer-sized clusters that are dispersed on the pore wall.

<p>Fluorochlorozirconate (FCZ) glasses are a member of heavy metal fluoride glasses, and are derived from a well known ZBLAN glass. In this work, halogen salts of europium (Eu²⁺) and samarium (Sm³⁺) are used as dopants in FCZ glasses. FCZ glasses doped with Eu²⁺ and Sm³⁺ can be used in high resolution x-ray imaging for tissue scanning, and have been shown to behave as storage phosphors and/or x-ray scintillators.</p> <p>Glass transition (T_g), heat capacity (C_p) and glass crystallization (T_c) properties of Eu²⁺ and Sm³⁺ doped and undoped FCZ glasses with different amounts of relative Cl concentration, that is, with respect to the total Cl and F concentration have been investigated by conventional differential scanning calorimetry (DSC) and modulated differential scanning calorimetry (MDSC) techniques. MDSC experiments were performed at different heating rates to analyze the complex transitions and to get a better resolution of any overlapping transitions. The crystallization kinetics have also been studied by applying the Kissinger technique to multiple DSC scans in order to determine the thermal stability of FCZ glass samples used in this work. The apparent activation energy for the crystallization process was obtained by the crystallization peak temperature shift method in the conventional DSC mode. The specific heat capacity (C_p) has been measured as a function of composition, and the glass transition temperature (T_g) is evaluated from the smooth change in the heat capacity curve during the glass transformation. The observation of two possible glass transitions points to the presence of two phases in these FCZ glasses with higher relative Cl content.</p> <p>Optical transmission spectra of both doped and undoped FCZ glass samples have been measured by infrared spectroscopy and optical band gaps corresponding to an absorption coefficient of 10³ cm^-1 have been determined. A good correlation between X-ray luminescence and the glass structure is observed. While the integrated photoluminescence intensity increases linearly with the Sm³⁺ concentration, the integrated X-ray luminescence increases sublinearly. The importance of appropriate annealing conditions, such as temperature, time and ambient atmosphere, and their effect on the X-ray luminescence of rare earth (RE) doped FCZ glass samples have been investigated. Annealing conditions influence the formation of BaCl₂ nanocrystals in the glass and the properties of the resulting FCZ glass ceramics.</p>

<p>Fluorochlorozirconate (FCZ) glasses are a member of heavy metal fluoride glasses, and are derived from a well known ZBLAN glass. In this work, halogen salts of europium (Eu²⁺) and samarium (Sm³⁺) are used as dopants in FCZ glasses. FCZ glasses doped with Eu²⁺ and Sm³⁺ can be used in high resolution x-ray imaging for tissue scanning, and have been shown to behave as storage phosphors and/or x-ray scintillators.</p> <p>Glass transition (T_g), heat capacity (C_p) and glass crystallization (T_c) properties of Eu²⁺ and Sm³⁺ doped and undoped FCZ glasses with different amounts of relative Cl concentration, that is, with respect to the total Cl and F concentration have been investigated by conventional differential scanning calorimetry (DSC) and modulated differential scanning calorimetry (MDSC) techniques. MDSC experiments were performed at different heating rates to analyze the complex transitions and to get a better resolution of any overlapping transitions. The crystallization kinetics have also been studied by applying the Kissinger technique to multiple DSC scans in order to determine the thermal stability of FCZ glass samples used in this work. The apparent activation energy for the crystallization process was obtained by the crystallization peak temperature shift method in the conventional DSC mode. The specific heat capacity (C_p) has been measured as a function of composition, and the glass transition temperature (T_g) is evaluated from the smooth change in the heat capacity curve during the glass transformation. The observation of two possible glass transitions points to the presence of two phases in these FCZ glasses with higher relative Cl content.</p> <p>Optical transmission spectra of both doped and undoped FCZ glass samples have been measured by infrared spectroscopy and optical band gaps corresponding to an absorption coefficient of 10³ cm^-1 have been determined. A good correlation between X-ray luminescence and the glass structure is observed. While the integrated photoluminescence intensity increases linearly with the Sm³⁺ concentration, the integrated X-ray luminescence increases sublinearly. The importance of appropriate annealing conditions, such as temperature, time and ambient atmosphere, and their effect on the X-ray luminescence of rare earth (RE) doped FCZ glass samples have been investigated. Annealing conditions influence the formation of BaCl₂ nanocrystals in the glass and the properties of the resulting FCZ glass ceramics.</p>

The behavior of polymeric systems confined into thin films is a situation that has numerous practical consequences. One particular application in which the properties of thin polymer films is becoming crucially important is in the design, formulation, and processing of photoresists for semiconductor microlithography. As devices continue to be scaled down into the nano-regime, the microelectronics industry will ultimately rely upon a molecular understanding of materials for process development. The majority of these devices are now confined in planar geometries; thus, thin films have played an ever-increasing role in manufacturing of modern electronic devices. This movement towards thinner resist films creates larger surface to volume ratios, and hence thin films can exhibit thermodynamic, structural, and dynamic properties that are different from those of the bulk material. It is thus extremely important to understand the properties of polymers when confined in such geometries for various applications including resists for lithographic patterning. In present work, the influence of a variety of factors including film thickness, molecular weight, and substrate interactions on the polymer thin film physical properties such as the glass transition temperature, coefficient of thermal expansion, dissolution rate, and diffusion coefficient was studied in detail using a combination of experimental characterization and molecular modeling simulation techniques.

This study indicate that the chemical inter-diffusion between the Cr-doped glass/glass ceramic and quartz (SiO2) influence the fluorescence properties of glass, mainly because of Cr4+ replacing by tetrahedral of Si4+. Cr4+ fluorescence intensity was reduced and its emission band was shifted to longer wavelength (red shift). We selected the SiO2-based glass composition: Mg2SiO4 glass-ceramic and reduced a ratio of SiO2 sintered into the ceramic powder. This paper used diffusion characteristics of quartz (SiO2) to compensate for reduced SiO2 in the ceramic powder. After diffusing with quartz (SiO2), ceramics powder changed into glasses. The intensity of fluorescence and the crystal field had been improved. The center of Cr4+ fluorescence is about 1100nm belonging to Cr4+:Mg2SiO4 crystal. The ratio of Cr4+ in Mg2SiO4 crystal/Cr4+ in MgO-SiO2 glass increases from 0.33 to 1.74. The goal is to develop a novel glass which is resistant to SiO2 inter-diffusion degradation during fiber fabrication, and provide the new fiber technology to avoid the influence of inter-diffusion This study provides new types of treatment: Laser induced crystallization. Laser heat-treatment can more quickly induce crystals in glass during seconds, than traditional heat-treatment which require several hours. This study also indicate that one step laser heat-treatment induce micro-crystals, but one step laser heat-treatment induce nano-crystals. We successfully produced nano-crystallization during seconds.

Using low-temperature (650¢J) Ce3+:YAG doped glass (LTCeYDG) phosphor layer instead of conventional Ce:YAG doped silicone phosphor layer applied to high-power phosphor-converted white-light-emitting diodes (PC-WLEDs) is demonstrated.The glass transition temperature (Tg) of silicone is 150¢J but glass is 750¢J,it shows the glass were employed in high power LED than silicon. The uniformity of phosphor powder doped glass is an important item to discriminates between good and bad. Quantize the uniformity of glass phosphor by image processing software and Distribution Uniformity (Du). Calculate the uniformity of phosphor powder mix with glass powder which has different particle size and measurement optical properties of glass phosphor which has different uniformity. The Du of glass phosphor are 64.46%, 84.65%, 85.24% , 91.85% and the quantum efficiency are 18.49%, 28.31%, 29.73%, 28.56% ,respectively. By using Ceramic tube and low temperature glass powder sintering glass phosphor is a new fabrication. Compare with last fabrication, new fabrication reduce 100¢Jfabrication temperature from 750¢J to 650¢J, 70% material savings and high luminous efficiency. The quantum efficiency and lumen per watt were improved about 7 percentage point from 22.3% to 29.1% and 4.2 lm/W from 36.4 lm/W to 40.68 lm/W. We used the XRD to analyze the glass phosphor of last fabrication and new fabrication and the results show that the higher thermal stress destroys the structure of YAG, lower fabrication temperature used to get higher luminous efficiency.

Metallic glasses can be considered for many commercial applications because of the higher mechanical strength, corrosion and wear resistance when compared to crystalline materials. To consider them for novel applications, the challenge of preparing metallic glasses from the liquid melt phase and how the properties of metallic glasses change due to relaxation need to be understood better. The glass forming ability (GFA) with variation in composition and inclusion of different alloying elements was studied by using thermal techniques to determine important GFA indicators for Zr-based bulk metallic glasses (BMG). The effect of alloying elements, annealing temperature and annealing time on the thermal and structural relaxation of the BMGs was studied by using an annealing induced relaxation approach. The thermal relaxation was studied by measuring specific heat of the samples using differential scanning calorimeter (DSC) and calculating the enthalpy recovery on reheating in the BMG samples. The structural relaxation was also studied by using extended X-ray absorption fine structure (EXAFS) technique on the as-obtained and relaxed samples. The effects of alloying elements and annealing on electrical resistance were studied by using a two point probe. From the study, it was found that the currently used GFA indicators are inadequate to fully capture and identify the best GFA BMGs. The fragility (beta) of the melt is a new criterion that has been proposed to measure and analyze GFA. The enthalpy relaxation of Zrbased BMGs was found to follow a stretched exponential function, and the parameters obtained showed the BMGs used in the current study are strong glass formers. EXAFS studies showed variations in the structure of BMGs with changes in alloying elements. Furthermore, alloying elements were found to have an effect on the structure of the relaxed BMGs. The resistance of BMGs was found to decrease with relaxation which can be attributed to short range order on annealing.