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ledemi_yag_dr_araiq.pdf: 4381823 bytes, checksum: a988190ae336a68b630fd0469bbb9ed7 (MD5) / Les travaux présentés dans ce manuscrit concernent l’étude de nouvelles vitrocéramiques transparentes à base de chalco-halogénures dopées par des ions de terres pour la luminescence dans le visible. L’addition de différents halogénures d’alcalins à des verres du système Ga2S3-GeS2 a été étudiée avec l’objectif d’étendre leur transparence vers l’ultraviolet. Des verres du système Ga2S3- GeS2-CsCl complètement transparents dans le visible (400-750 nm) jusqu’au moyen infrarouge (11,5 μm) ont été obtenus. Des vitrocéramiques transparentes et homogènes ont ensuite été préparées de manière contrôlée à partir de plusieurs verres à différentes teneurs en CsCl dans le système Ga2S3-GeS2-CsCl. Des nanocristallites de taille homogène et uniformément dispersées dans la matrice amorphe sont formées de manière reproductible par des traitements thermiques appropriés. Une étude d’un point de vue structural de la cristallisation a été réalisée par diffraction de rayons X et résonance magnétique nucléaire à l’état solide sur les noyaux 71Ga et 133Cs. Le rôle d’agent de nucléation du gallium a été mis en évidence dans cette matrice avec la cristallisation d’une phase Ga2S3. Un meilleur comportement mécanique a également été observé pour les matériaux composites préparés. Des vitrocéramiques dopées par des ions de terres rares (praséodyme Pr3+ et néodyme Nd3+) ont été synthétisées dans le système Ga2S3-GeS2-CsCl. L’évolution de la luminescence dans le visible des ions Pr3+ et Nd3+ a été étudiée en fonction des conditions de traitement thermique. Au vu des résultats obtenus, il semble que l’ion Pr3+ ne soit pas incorporé dans les cristallites. Une augmentation de la luminescence de l’ion Nd3+ a en revanche été constatée, suggérant une incorporation partielle de ces ions dans une phase cristalline... (Résumé complet accès électronique ci - dessous) / Vitrocerâmicas transparentes baseadas em novas composições de calco-halogenetos dopadas com íons de terras raras foram produzidas com o objetivo de gerar luz no visível. A adição de diferentes halogenetos alcalinos em vidros do sistema Ga2S3-GeS2 foi estudada com a finalidade de aumentar a sua janela de transparência no ultravioleta. Vidros no sistema Ga2S3- GeS2-CsCl totalmente transparentes no visível (400-750 nm) até a região do infravermelho médio (11,5μm) foram obtidos. Vitrocerâmicas transparentes e homogêneas foram em seguida preparadas a partir de vidros variando a concentração de CsCl no sistema Ga2S3-GeS2-CsCl. As condições dos tratamentos térmicos (temperaturas e tempos) foram estabelecidas permitindo o controle dos processos de nucleação e crescimento dos cristalitos dentro da matriz vítrea. Nanocristalitos uniformemente distribuídos e com tamanho homogêneo foram obtidos e confirmados por microscopia eletrônica de varredura (MEV) e microscopia eletrônica de transmissão (MET). Estudos estruturais foram realizadas nas vitrocerâmicas utilizando-se as técnicas de difração de raios X e resonância magnetica nuclear do sólido do 133Cs e 71Ga. Foi evidenciado o papel do agente de nucleação do gálio neste material, com a cristalização da fase Ga2S3. Um aumento da resistência mecânica foi também observado nestes materiais em comparação aos vidros de base. Em seguida, vitrocerâmicas dopadas com íons de terras raras (praseodímio Pr3+ e neodímio Nd3+) foram sintetizadas no sistema Ga2S3-GeS2-CsCl. A luminescência dos íons Pr3+ e Nd3+ no visível foi estudada em função dos tratamentos térmicos aplicados aos materiais. Foi observado que não houve a incorporação dos íons Pr3+na matriz. Por outro lado, um aumento da fluorescência do íon Nd3+ foi observado, sugerindo uma incorporação parcial destes íons dentro da fase cristalina... / The present work deals with the study of new chalco-halide glass-ceramics doped with rare earth ions for visible luminescence. The effect of the addition of different alkali-halide into glasses belonging to the Ga2S3-GeS2 system has been studied with the aim to extend their transparency into the ultraviolet region. Glasses transparent over the visible range (400-750 nm) up to the mid infrared (11,5 μm) have been obtained in the Ga2S3-GeS2-CsCl system. Transparent and homogeneous glass-ceramics have been prepared from several base glasses varying the CsCl content in the Ga2S3-GeS2-CsCl system. Nanocrystals with homogeneous size and uniformly distributed in the amorphous matrix have been generated with reproducibility by appropriate heat-treatment. A structural study of the crystallization has been realized using X-ray diffraction and solid state nuclear magnetic resonance performed on the 71Ga and 133Cs nuclei. The nucleating agent character of gallium has been shown in the glassy matrix with the crystallization of the Ga2S3 phase. An improved mechanical behaviour has also been observed in the prepared composite materials. Rare-earth ion (praseodymium Pr3+ and neodymium Nd3+) doped glass-ceramics have been synthesized in the Ga2S3-GeS2-CsCl system. The visible luminescence from Pr3+ and Nd3+ ions has been studied as a function of heat-treatment conditions. It appeared from experiments that Pr3+ ions are not incorporated into the crystals contrary to the Nd3+ ions from which an enhanced luminescence was observed, suggesting their partial integration into the crystalline phase. Finally, silver and Pr3+ doped glasses have been synthesized in the Ga2S3-GeS2 system. Metallic silver nanoparticles were generated by heat-treatment at 370°C and characterized by transmission electronic microscopy. The influence of the NPs on the Pr3+ ions luminescence properties was studied by performing frequency... (Complete abstract click electronic access below)
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.unesp.br:11449/105794 |
| Date | 24 October 2008 |
| Creators | Ledemi, Yannick André Georges [UNESP] |
| Contributors | Universidade Estadual Paulista (UNESP), Bureau, Bruno [UNESP], Messaddeq, Younes [UNESP], Poulain, Marcel [UNESP] |
| Publisher | Universidade Estadual Paulista (UNESP) |
| Source Sets | IBICT Brazilian ETDs |
| Language | fra |
| Detected Language | French |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Format | 186 f. : il. |
| Source | Aleph, reponame:Repositório Institucional da UNESP, instname:Universidade Estadual Paulista, instacron:UNESP |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | -1, -1, -1, -1 |
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