Search results for "silica."

Obturación de los conductos radiculares con cementos biocerámicos y gutapercha recubierta del mismo material: análisis morfológico de las interfases …

2020

OBJETIVO Evaluar la relación entre cuatro cementos endodónticos (uno basado en resina y tres basados en materiales biocerámicos) y la dentina del conducto radicular, así como la unión entre el núcleo de gutapercha (convencional y recubierta de material biocerámico) y los cementos. MATERIAL Y MÉTODOS Se seleccionaron 80 dientes unirradiculares, verificados previamente de forma radiográfica. Estos se se dividieron en 4 grupos (n=20) de acuerdo al cemento de obturación: 1 (MTA FillApex), 2 (EndoSequence BC Sealer), 3 (Bio Root) y 4 (AHPlus). A su vez cada grupo se dividió en dos (ni=10) según la gutapercha empleada, convencional o recubierta de material biocerámico. Los dientes se decoronaron …

Optical Absorption of Excimer Laser‐Induced Dichlorine Monoxide in Silica Glass and Excitation of Singlet Oxygen Luminescence by Energy Transfer from…

2021

An optical absorption (OA) band of interstitial dichlorine monoxide molecules with peak at 4.7 eV and halfwidth 0.94 eV is identified in F2 laser - irradiated (photon energy=7.9 eV) synthetic silica glass bearing both interstitial O2 and Cl2 molecules. Alongside with intrinsic defects, this OA band can contribute to solarization of silica glasses produced from SiCl4. While the formation of ClClO is confirmed by its Raman signature, its structural isomer ClOCl may also contribute to this induced OA band. Thermal destruction of this band between 300C and 400C almost completely restores the pre-irradiation concentration of interstitial Cl2. An additional weak OA band at 3.5 eV is tentatively a…

Etude spectroscopique de fibres durcies pour un environnement radiatif sévère

2013

Les nouveaux environnements radiatifs, comme LMJ, ITER, ILE/ELI, HiPER, réacteurs nucléaires des générations III+ et IV, nécessitent le développement de nouveaux composants pour le transport et le traitement des signaux. A cause de l’impossibilité d’utiliser les composants électroniques, la recherche est orientée vers les composants à fibres optiques comme vecteur d’information et aussi comme élément de diagnostic. Ils présentent de nombreux avantages, comme leur relative immunité électromagnétique, faible pois, large bande passante, mais les rayonnements gamma et les neutrons dégradent leur transmission. La dégradation dépend principalement de la composition de la fibre. Ainsi, il a été mo…

O2-Loading Treatment of Ge-Doped Silica Fibers: A Radiation Hardening Process

2016

International audience; The effects of a high-pressure O2-loading treatment on the radiation response of Ge-doped optical fibers (OFs) were investigated. We found that the incorporation of high concentration of interstitial molecular oxygen remarkably enhances the resistance to ionizing radiation of Ge-doped OFs in the UV-Visible domain and, at the same time, improves the transmission of UV light in the unirradiated OF sample. By comparison with previously reported results, the O2-loading treatment turned out to increase the radiation resistance of Ge-doped OFs more efficiently than F or Ce codoping. The understanding of such amelioration relies in basic radiation-induced mechanisms that we…

Radiation Response of Ce-Codoped Germanosilicate and Phosphosilicate Optical Fibers

2016

We report an experimental investigation on the effects of Ce-codoping in determining the radiation response of germanosilicate and phosphosilicate Optical Fibers (OFs) in the UV-Visible domain and up to doses of $1~\hbox{MGy}({\rm SiO}_{2})$ . We show that the addition of Ce strongly impacts the Radiation Induced Attenuation (RIA) of both types of fibers. In the first case the radiation induced losses increase, whereas in the second one decrease. By combining the online RIA measurements with the Electron Paramagnetic Resonance (EPR) ones, we are able to infer the basic microscopic mechanisms taking place under irradiation, which involve the cerium codopant and some of the known Ge-related o…

Approche couplée pour le développement de matériaux optiques résistants aux radiations

2011

National audience; De très nombreuses applications sont aujourd'hui envisagées pour les matériaux optiques en environnement radiatif. Ce regain d'intérêt pour l'usage de verres ou fibres optiques dans des environnements hostiles s'explique par leurs avantages inhérents en particulier leur immunité électromagnétique. En revanche, il est également bien établi que les radiations entrainent la génération de défauts ponctuels dans verres amorphes. Ces défauts vont, au niveau macroscopique, entrainer une altération des propriétés optiques du matériau, le plus souvent de la silice amorphe pure ou dopée. Ainsi, les fibres optiques vont, sous irradiation, voir leur atténuation linéique augmenter, po…

Influence du rayonnement X sur des fibres et préformes canoniques dopées au phosphore

2009

The relevance of point defects in studying silica-based materials from bulk to nanosystems

2019

The macroscopic properties of silica can be modified by the presence of local microscopic modifications at the scale of the basic molecular units (point defects). Such defects can be generated during the production of glass, devices, or by the environments where the latter have to operate, impacting on the devices’ performance. For these reasons, the identification of defects, their generation processes, and the knowledge of their electrical and optical features are relevant for microelectronics and optoelectronics. The aim of this manuscript is to report some examples of how defects can be generated, how they can impact device performance, and how a defect species or a physical phenomenon …

Near‐IR Radiation‐Induced Attenuation of Aluminosilicate Optical Fibers

2021

The X-ray radiation-induced attenuation (RIA) growth kinetics are studied online in different single-mode aluminosilicate optical fibers in the near-IR (NIR) domain to evaluate their potential in terms of dosimetry. The optical fibers differ by Al contents, core sizes, drawing parameters, and also by a preform deposition process. The data show no dependence of the RIA on all these parameters, a positive result for the design of point or distributed radiation detectors exploiting RIA to monitor the dose. The RIA growth rate is unchanged for dose rates changing from 0.073 to 6.25 Gy(SiO2) s−1, and the RIA linearly increases with the dose up to 2 kGy(SiO2). Small but noticeable RIA changes are…

Study of the Effect of Two Phases in Li4SiO4–Li2SiO3 Ceramics on the Strength and Thermophysical Parameters

2022

This research was funded by the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan (No. BR11765580). The research of the team from Latvia (A.M., V.P. and A.I.P.) has been carried out within the framework of the EUROfusion Consortium, funded by the European Union via the Euratom Research and Training Programme (Grant Agreement No. 101052200—EUROfusion). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Commission. Neither the European Union nor the European Commission can be held responsible for them. The research was partly (A.M., V.P. and A.I.P.) performed in …