Made available in DSpace on 2017-07-21T19:25:46Z (GMT). No. of bitstreams: 1 Joao Luiz Gomes Junior.pdf: 5004861 bytes, checksum: 0e45ece35c737cce76186e1babb5e257 (MD5) Previous issue date: 2015-03-26 / Fundação Araucária de Apoio ao Desenvolvimento Científico e Tecnológico do Paraná / In this work, the correlation between the structural morphology with thermal, optical and mechanical properties of (1 – x – y)TeO2-xLi2O-yMoO3 glasses was studied. The analysis was divided into three sets of samples, varying according to the composition for technique. The results reveal different behaviors for each set vitreous stabilities. The Raman spectroscopy and FTIR results showed a similar structural change between each set with decrease NBOs and new peaks position. The Raman and FTIR spectra results showed that with increasing content x and y, concomitantly, occur the conversion of TeO4 to TeO3+1 units, then, in addition to TeO3 units. Furthermore occurs change coordination in the structural units Mo atoms 4 to 6 and these structural changes. Li addition causes these structural changes. This fact confirmed by the Band Gap energy values, which increase with the increase of x and y, it decreases the optical basicity and refractive index values. By optical absorption measurements determined the Band Gap energy values of all samples. It was concluded that occur direct transitions allowed in all sets. The behavior of increasing Band Gap values and decreasing Optical basicity confirmed the decreasing in the NBO content leading to an indication of a more polymerized network for a variation of x mol%. Finally the behaviors elastic modulus and hardness, which shows decreased stiffness of the material with the incorporation of Li2O and MoO3 concomitantly, is presented. x / Este trabalho apresenta as correlações entre a morfologia estrutural e as propriedades térmicas, ópticas e mecânicas nos vidros (1 – x – y)TeO2 – xLi2O – yMoO3. Dividiram-se as análises em três conjuntos de amostras, de acordo com variação da composição, para cada técnica utilizada. Os resultados revelam diferentes comportamentos de estabilidades vítreas para cada conjunto. As medidas por espectroscopia de Raman e FTIR mostram mudanças estruturais similares entre cada conjunto com diminuição dos NBOs e novas posições de picos. Os resultados de Raman e FTIR mostram que com o aumento em conteúdo x e y ocorre a transformação de unidades TeO4 para TeO3 + 1 e, em seguida, para TeO3 além disso ocorre a mudança de coordenação do átomo de Mo de 4 para 6 e estas alterações estruturais têm sido relacionados com a adição de átomos de Li. Este fato é confirmado pelos valores de energia de Band Gap, que aumentam com o incremento de x e y, e diminuição dos valores de basicidade óptica e índice de refração. As energias de Band Gap, para todas as amostras, foram determinadas por medidas de absorção óptica na região do Ultravioleta. Foi concluído que ocorrem transições diretas permitidas em todos os conjuntos. E por fim apresenta-se os comportamentos de dureza e Módulo elástico, o que revela diminuição da rigidez do material com a incorporação de Li2O e MoO3 concomitantemente.

Le nouvel essor industriel du marché des applications mobiles telles que les smartphones ou les tablettes tactiles nécessite de nombreuses recherches afin de concevoir des écrans en verres encore plus résistant. Le procédé d’échange ionique au potassium permet d’améliorer la résistance mécanique des verres grâce à la substitution des ions Na⁺ par des ions K⁺, de plus gros rayon ionique. Elle permet ainsi de bloquer les fissures superficielles du verre et de réduire la casse du matériau. Ce travail est consacré à comprendre le principe de diffusion des ions K⁺ au sein de la structure silicatée de différents verres. Les paramètres, temps, température et composition verrière, influent sur la cinétique de l’échange ionique. Dans les mêmes conditions de trempe, la réduction de la composition à un formateur et à l’ion mobile permet d’améliorer la diffusion et la propagation des ions au sein du matériau. Les conditions de trempe, thermique et temporelle, agissent sur la cinétique de diffusion des ions. Elles réduisent la facilité de déplacement des ions à travers la structure silicaté du matériau avec un changement de comportement au-delà de 8h d’immersion dans les sels fondus. La substitution des Na⁺ par les ions K⁺ et leur différence de taille modifient l’environnement des sites laissés vacants par les ions Na⁺ et modifie la structure silicatée du verre. La spectroscopie IR permet de mettre en évidence les modifications structurales des verres soumis à ce procédé d’échange ionique. Lors de l’introduction des ions K⁺, la structure du verre se dépolymérise et crée des oxygènes non pontants. Ceci permet de montrer que l’échange ionique conduit à l’amélioration du renforcement mécanique des verres. / The new industrial boom of the market for mobile applications such as smartphones or tablets requires much research in order to touch-screens design more resistant. The potassium ion exchange process improves the mechanical strength of glass by Na⁺ ions substitution with K⁺ ions, of larger ionic radius. It thus helps to block surface cracks in glass and reduce breakage of the material. This work is devoted to understand the principle of K⁺ diffusion in the silicate structure of different glasses. The parameters: time, temperature and glass composition affect the kinetic of ion exchange process. In the same quenching conditions, the limitation of the composition just to a former network and a mobile ion can improve the diffusion and the penetration ions inside the material. The quenching conditions, temperature and time, act on the kinetic diffusion. They reduce the mobility of the ions through the structure of the silicate material with a change of behaviour above 8h immersion in molten salts. Substitution of Na⁺ by K⁺ ions having different size affect the environment of the sites left vacant by the Na⁺ ions and modifies the silicate structure of the glass. IR spectroscopy allows highlighting the structural modifications of the glass submitted to this ion exchange process. During the introduction of the K⁺ ions inside the glass, the silicate structure is depolymerized and creates no-bridging oxygens. This allows to demonstrate that the ion exchange lead to the mechanical improvement of the glass.