Abstract During their use, optical fibers are subject to harsh installation and environmental conditions. To evaluate more precisely the lifetime of an optical fiber, it is necessary to study the mechanical behavior of optical fibers under extreme conditions, in particular under mechanical and thermal stresses. This paper presents the results of new silica optical fibers aged in hot water between 20 °C and 70 °C and subjected to mechanical static bending stresses from 3 GPa to 3.5 GPa. Thermal dependence of the time to failure was observed. This dependence can be described by the Arrhenius model, where the activation energy is one of the main physical characteristic. The stress corrosion parameter also seems to regularly change with temperature.

A partir de resultados de experimentos de fusão e choque térmico, o domínio vítreo foi identificado no sistema PbF2-CdF2-B2O 3. Vidros puros e dopados com Er3+ foram preparados e vitrocerâmicas foram obtidas a partir de tratamentos térmicos adequados. A fase cristalina foi identificada como beta-PbF2. Estudos estruturais foram efetuados por difração e absorção de raios X e o papel desempenhado pelos átomos de Pb2+ e Cd2+ na estrutura vítrea foi estabelecido a partir destas técnicas. Os resultados sugerem que, com a cristalização, os íons Er3+ são segregados na fase cristalina.

The vitreous domain was established in the PbF2-CdF2-B2O 3 system from melting and quenching experiments. Er3+ containing glasses were prepared and glass ceramics were obtained by selected heat-treatments. Lead fluoride was identified (beta-PbF2) as the crystalline phase. Structural studies were performed in some glassy and partially crystallized samples by means of X-ray Diffraction (XRD) and Extended X-ray Absorption Fine Structure (EXAFS) measurements. The role of Cd2+ and Pb2+ atoms on the glass network formation and also on the crystallization behavior was put forward by these techniques. After crystallization Er3+ atoms segregated in the crystal phase.