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Doctoral Thesis
DOI
10.11606/T.43.1996.tde-15082012-154441
Document
Author
Full name
Urias Echterhoff Takatohi
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 1996
Supervisor
Committee
Watanabe, Shigueo (President)
Bressiani, José Carlos
Martinelli, José Roberto
Pontuschka, Walter Maigon
Rouse, Colin Graham
Title in Portuguese
Preparação e Propriedades de Vidros Fotocrômicos Dopados com Cloreto de Prata
Keywords in Portuguese
Absorção óptica
Fotocromismo
Saxs
Vidro
Abstract in Portuguese
Este trabalho teve por objetivo o preparo e estudo das propriedades de vidros fotocrômicos. Foram preparados vidros de aluminoborosilicatos de potássio (40'SI''O IND. 2'.10'AL IND. 2''O IND. 3'.(50-x)'B IND. 2''O IND. 3'.X'K IND. 2''O'- 14,9 < x < 17,7) dopados com 'AG''CL' e 'CU POT. 2+'. As amostras foram fundidas em cadinho de platina, em forno de elementos resistivos de 'SI''C', a '1400 GRAUS'C por duas horas, sendo derramados sobre molde de aço inoxidável. Uma tentativa de análise química quantitativa dos componentes após a fusão foi feita por Retroespalhamento de Rutherford. A proporção de prata retida no vidro foi determinada por este método. Medidas de dilatometria e densidade foram feitas para amostras de composição base diferentes. As medidas de dilatometria permitem a obtenção do coeficiente de dilatação térmica, e os parâmetros típicos de vidros conhecidos como: temperatura de transição vítrea e temperatura de "softening dilatométrico". Tratamentos térmicos em temperaturas próximas do ponto de amolecimento (softening point) provocam a precipitação de partículas coloidais de 'AG''CL' na matriz vítrea. Estas são responsáveis pelo comportamento fotocrômico dos vidros. Fatias de uma amostra foram submetidas a programas de tratamento térmico de 0,5 h a várias temperaturas entre '480 GRAUS'C e '620 GRAUS'C e programas de vários intervalos de tempo entre 0,25 e 1,25h a '600 GRAUS'C. As propriedades de absorção óptica das várias fatias, antes e depois de exposição à luz UV, foram comparadas. As características morfológicas das partículas coloidais de 'AG''CL' produzidas pelos tratamentos térmicos foram investigadas por SAXS. Os raios R das partículas mostraram uma relação linear com a temperatura para tratamentos de 0,5 h entre 550 e '620 GRAUS'C e uma relação linear de 'R POT. 3' com o tempo de tratamento a '600 GRAUS'C. Duas séries de amostras foram preparadas para estudar: 1. a influência da quantidade de cobre 2. a influência da proporção de 'K IND. 2''O' em relação a 'B IND. 2''O IND. 3'. As propriedades de absorção óptica (antes e depois de exposição à luz UV) das amostras das duas séries, submetidas a tratamentos térmicos a '600 GRAUS'C por diversos tempos entre 0,25 e 1,6 h foram comparadas.
Title in English
Preparation and properties of photochromic glasses doped with Silver Chloride
Keywords in English
Glass
optical absorption
photochromism
SAXS
Abstract in English
The purpose of the present work was to prepare and study the properties of photochromic glasses. Potassium aluminoborosilicate glasses (40'SI''O IND. 2'.10'AL IND. 2''O IND. 3'.(50-x)'B IND. 2''O IND. 3'.X'K IND. 2''O'- 14,9 < x < 17,7) doped with 'AG''CL' and 'CU POT. 2+' were prepared. The samples were melted in platinum crucible, in electric furnace with silicon carbide resistences, at '1400 GRAUS'C for two hours, and poured on stainless steel mold. An attempt to perform a quantitative chemical analisis of the components after melting was carried out by Rutherford Backscattering method. The amount of silver incorporated into the glass was determined by this method. Measurements of dilatometry and density were performed for samples of different base composition. The dilatometric measurements give the thermal expansion coefficient, and the typical glass parameters such as glass transition point and dilatometric softening point. Thermal treatments at temperatures near the softening point precipitate colloidal 'AG''CL' particles in the glass matrix. These particles are responsible for the photochromic characteristics of the glass. Slices of a sample were submitted to thermal treatments for 0.5 hours at temperatures between 480 and '620 GRAUS'C and treatments at '600 GRAUS'C for several) time intervals between 0.25 and 1.25 hours. The optical absorption properties of these slices, before and after UV light exposure, were compared. The morphological aspects of the 'AG''CL' coloidal particles were investigated by SAXS. The particle radii R presented a linear relation with the temperature for treatments for 0.5 hour at temperatures between 550 and '620 GRAUS'C and a linear relation of 'R POT. 3' with time for treatments at '600 GRAUS'C. Two sample series were prepared to investigate: 1. the influence of the amount of copper 2. the influence of the amount of 'K IND. 2''O' in relation to the amout of 'B IND. 2''O IND. 3' The optical absorbances (before and after exposure to UV light) for samples of the two series, annealed at '600 GRAUS'C for different times between 0.25 and 1.6 hours were compared.
 
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46150Takatohi.pdf (41.76 Mbytes)
Publishing Date
2012-08-15
 
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