Vitrocerámicos transparentes del sistema SiO2-Al2O3-Na2O-K2O-LaF3/YF3: Mecanismos de cristalización y propiedades ópticas

Rare-earth (RE) doped oxyfluoride glass-ceramics possess interesting optical properties with applications in telecommunications and optoelectronics. These materials combine the transparency and mechanical and chemical resistance of aluminosilicate glasses with the low phonon energy and facile incorp...

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Autor: Pablos Martín, Araceli de
Tipo de recurso: tesis doctoral
Fecha de publicación:2012
País:España
Institución:Consejo Superior de Investigaciones Científicas (CSIC)
Repositorio:DIGITAL.CSIC. Repositorio Institucional del CSIC
OAI Identifier:oai:digital.csic.es:10261/50496
Acceso en línea:http://hdl.handle.net/10261/50496
Access Level:acceso abierto
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spelling Vitrocerámicos transparentes del sistema SiO2-Al2O3-Na2O-K2O-LaF3/YF3: Mecanismos de cristalización y propiedades ópticasPablos Martín, Araceli deRare-earth (RE) doped oxyfluoride glass-ceramics possess interesting optical properties with applications in telecommunications and optoelectronics. These materials combine the transparency and mechanical and chemical resistance of aluminosilicate glasses with the low phonon energy and facile incorporation of RE ions in the fluoride crystals. The incorporation of RE ions in the crystalline phases enhances the optical emission intensity, a major property of these materials. Nanocrystallization in four different oxyfluoride glasses in the system SiO2- Al2O3-Na2O-K2O-LaF3/YF3 has been studied. Heat treatments above the glass transition temperature give rise to the devitrification of different crystalline phases, depending on the composition: LaF3, NaLaF4, KLaF4 and NaYF4. Crystalline fraction and crystal size are dependent on the time and temperature of thermal treatment. Thermal and structural characterisation has been studied using several techniques, including viscosity, dilatometry, X-ray and neutron diffraction, quantitative Rietveld refinement, transmission electron microscopy techniques (EELS, EFTEM, Simulations), differential scanning calorimetry (DSC), 27Al, 19F and 23Na NMR, and EXAFS. The crystallization mechanism is shown to occur via regions of La- and Siphase separation in the glass, from which the fluoride crystals develop during heat treatment. The interface between the glass matrix and the crystals in the demixed ranges is enriched in network formers, mainly SiO2, creating a viscous barrier, which inhibits further crystal growth and limits the crystal size to the nanometric range. The influence of the addition of RE ions (Tm3+, Eu3+, Yb3+, Er3+) on nanocrystallisation has been analysed. The optical characterisation of the RE-doped glasses and glass-ceramics has been performed, mainly focussed on confirming the distribution of RE ions between glassy matrix and crystals, and on the upconversion (UC) emission processes (doping with Tm3+ provides an up UC 2 emission in the blue region (450-480 nm) from excitation in the NIR (790 nm)), and the differences between glasses and glass-ceramics. Finally, preliminary results of the production of waveguides through ionic exchange and their characterisation (optical modes, attenuation of light during propagation along the guide, stress profile) will be shownUniversidad Autónoma de MadridPascual, M. J.201220122012info:eu-repo/semantics/doctoralThesishttp://purl.org/coar/resource_type/c_db06http://hdl.handle.net/10261/50496reponame:DIGITAL.CSIC. Repositorio Institucional del CSICinstname:Consejo Superior de Investigaciones Científicas (CSIC)Inglésinfo:eu-repo/semantics/openAccessoai:digital.csic.es:10261/504962026-05-22T06:33:51Z
dc.title.none.fl_str_mv Vitrocerámicos transparentes del sistema SiO2-Al2O3-Na2O-K2O-LaF3/YF3: Mecanismos de cristalización y propiedades ópticas
title Vitrocerámicos transparentes del sistema SiO2-Al2O3-Na2O-K2O-LaF3/YF3: Mecanismos de cristalización y propiedades ópticas
spellingShingle Vitrocerámicos transparentes del sistema SiO2-Al2O3-Na2O-K2O-LaF3/YF3: Mecanismos de cristalización y propiedades ópticas
Pablos Martín, Araceli de
title_short Vitrocerámicos transparentes del sistema SiO2-Al2O3-Na2O-K2O-LaF3/YF3: Mecanismos de cristalización y propiedades ópticas
title_full Vitrocerámicos transparentes del sistema SiO2-Al2O3-Na2O-K2O-LaF3/YF3: Mecanismos de cristalización y propiedades ópticas
title_fullStr Vitrocerámicos transparentes del sistema SiO2-Al2O3-Na2O-K2O-LaF3/YF3: Mecanismos de cristalización y propiedades ópticas
title_full_unstemmed Vitrocerámicos transparentes del sistema SiO2-Al2O3-Na2O-K2O-LaF3/YF3: Mecanismos de cristalización y propiedades ópticas
title_sort Vitrocerámicos transparentes del sistema SiO2-Al2O3-Na2O-K2O-LaF3/YF3: Mecanismos de cristalización y propiedades ópticas
dc.creator.none.fl_str_mv Pablos Martín, Araceli de
author Pablos Martín, Araceli de
author_facet Pablos Martín, Araceli de
author_role author
dc.contributor.none.fl_str_mv Pascual, M. J.
description Rare-earth (RE) doped oxyfluoride glass-ceramics possess interesting optical properties with applications in telecommunications and optoelectronics. These materials combine the transparency and mechanical and chemical resistance of aluminosilicate glasses with the low phonon energy and facile incorporation of RE ions in the fluoride crystals. The incorporation of RE ions in the crystalline phases enhances the optical emission intensity, a major property of these materials. Nanocrystallization in four different oxyfluoride glasses in the system SiO2- Al2O3-Na2O-K2O-LaF3/YF3 has been studied. Heat treatments above the glass transition temperature give rise to the devitrification of different crystalline phases, depending on the composition: LaF3, NaLaF4, KLaF4 and NaYF4. Crystalline fraction and crystal size are dependent on the time and temperature of thermal treatment. Thermal and structural characterisation has been studied using several techniques, including viscosity, dilatometry, X-ray and neutron diffraction, quantitative Rietveld refinement, transmission electron microscopy techniques (EELS, EFTEM, Simulations), differential scanning calorimetry (DSC), 27Al, 19F and 23Na NMR, and EXAFS. The crystallization mechanism is shown to occur via regions of La- and Siphase separation in the glass, from which the fluoride crystals develop during heat treatment. The interface between the glass matrix and the crystals in the demixed ranges is enriched in network formers, mainly SiO2, creating a viscous barrier, which inhibits further crystal growth and limits the crystal size to the nanometric range. The influence of the addition of RE ions (Tm3+, Eu3+, Yb3+, Er3+) on nanocrystallisation has been analysed. The optical characterisation of the RE-doped glasses and glass-ceramics has been performed, mainly focussed on confirming the distribution of RE ions between glassy matrix and crystals, and on the upconversion (UC) emission processes (doping with Tm3+ provides an up UC 2 emission in the blue region (450-480 nm) from excitation in the NIR (790 nm)), and the differences between glasses and glass-ceramics. Finally, preliminary results of the production of waveguides through ionic exchange and their characterisation (optical modes, attenuation of light during propagation along the guide, stress profile) will be shown
publishDate 2012
dc.date.none.fl_str_mv 2012
2012
2012
dc.type.none.fl_str_mv info:eu-repo/semantics/doctoralThesis
http://purl.org/coar/resource_type/c_db06
format doctoralThesis
dc.identifier.none.fl_str_mv http://hdl.handle.net/10261/50496
url http://hdl.handle.net/10261/50496
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.publisher.none.fl_str_mv Universidad Autónoma de Madrid
publisher.none.fl_str_mv Universidad Autónoma de Madrid
dc.source.none.fl_str_mv reponame:DIGITAL.CSIC. Repositorio Institucional del CSIC
instname:Consejo Superior de Investigaciones Científicas (CSIC)
instname_str Consejo Superior de Investigaciones Científicas (CSIC)
reponame_str DIGITAL.CSIC. Repositorio Institucional del CSIC
collection DIGITAL.CSIC. Repositorio Institucional del CSIC
repository.name.fl_str_mv
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