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Master's Dissertation
DOI
10.11606/D.88.2010.tde-22092010-141421
Document
Author
Full name
Patricia Brajato
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 2010
Supervisor
Committee
Mastelaro, Valmor Roberto (President)
Ferreira, Eduardo Bellini
Rodrigues, Ana Candida Martins
Title in Portuguese
Síntese e caracterização do sistema vítreo B2O3-BaO-SiO2-Al2O3
Keywords in Portuguese
Cristalização
Fotossensibilidade
Morfologia
Vidros borossilicatos
Abstract in Portuguese
Este trabalho teve como principal objetivo a síntese e o estudo do processo de cristalização dos sistemas vítreos B2O3-BaO-SiO2, e B2O3-BaO-SiO2-Al2O3, assim como do sistema B2O3-BaO-SiO2 dopado com cério e prata. Amostras do sistema B2O3-BaO-SiO2 contendo 8 e 15% de SiO2, amostras do sistema B2O3-BaO-SiO2-Al2O3 contendo 2, 4 e 8 mol% de Al2O3 e amostras do sistema B2O3-BaO-SiO2 contendo 15% de SiO2 dopada com cério e prata foram caracterizadas através da técnica de analise térmica diferencial (DTA), difração de raios X (DRX), microscopia óptica (MO), espectroscopia Raman, medidas de transmissão na região do ultra-violeta/visível e medidas de luminescência. O estudo do processo de cristalização revelou que em todas as amostras prevaleceu o mecanismo de cristalização superficial. O tratamento térmico em temperaturas acima de Tg e abaixo de Tc levou a formação de uma única fase cristalina, a fase beta -BaB2O4 (beta-BBO). A morfologia dos cristais da fase beta -BBO presentes na superfície das amostras vítreas depende da quantidade de SiO2 e Al2O3. A amostra dopada com cério e prata quando submetida a radiação proveniente de um laser de HeCd e a um posterior tratamento térmico a 400 ºC apresentou somente um efeito de fotosensibilidade superficial devido a alta absorção dos átomos de cério presentes na amostra.
Title in English
Synthesis, characterization and crystallization the B2O3-BaO-SiO2-Al2O3 glass system.
Keywords in English
Borosilicate glasses
Crystallization
Morphology
Photosensitivity .
Abstract in English
The main purpose of this work was the synthesis and study of the crystallization process of B2O3-BaO-SiO2 and B2O3-BaO-SiO2-Al2O3 as well cerium and silver co-doped B2O3-BaO-SiO2 glassy systems. Samples of 8 and 15 mol% SiO2-containing B2O3-BaO-SiO2 system, 2, 4 and 8 mol% Al2O3-containing B2O3-BaO-SiO2-Al2O3 system and samples 15% mol % SiO2-containing B2O3-BaO-SiO2 system doped with cerium and silver were characterized by different techniques as differential thermal analysis (DTA), X-ray diffraction (XRD), optical microscopy (OM) and Raman spectroscopy. The study of the crystallization process showed that, in all the prepared samples, surface crystallization was the predominant mechanism. The heat treatment at temperatures above Tg and below Tc led to the formation of a single crystalline phase: beta-BaB2O4 (abbreviated as beta-BBO). The morphology of the crystals that appear at the glass surface depends on the amount of SiO2 and Al2O3 in the systems. When subjected to radiation from a HeCd laser and a subsequent heat treatment at 400 ºC, the glass system doped with cerium and silver, showed a photosensitivity effect on the surface due to high absorption of cerium atoms present on the glass sample.
 
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Publishing Date
2010-09-24
 
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