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Master's Dissertation
DOI
https://doi.org/10.11606/D.76.2005.tde-19092007-114452
Document
Author
Full name
Seila Silva Rojas
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 2005
Supervisor
Committee
Hernandes, Antonio Carlos (President)
Li, Maximo Siu
Yukimitu, Keizo
Title in Portuguese
Propriedades térmicas e estruturais do sistema CaB4O7-CaB2O4 visando o desenvolvimento de dosímetro termoluminescente
Keywords in Portuguese
Boratos
Dosimetria
Propriedades térmicas
Termoluminescência
Abstract in Portuguese
Vidros boratos contendo óxidos modificadores vêm sendo estudados por apresentarem um número atômico efetivo próximo ao do tecido humano, o que os tornam materiais interessantes para o desenvolvimento de dosímetros termoluminescentes. O objetivo deste trabalho foi estudar as propriedades térmicas e estruturais do sistema xCaB4O7-(100-x)CaB2O4, com x variando de 0 a 100 % em massa. As amostras sem dopantes foram previamente estudadas a fim de determinar uma composição que apresentasse a melhor resposta termoluminescente (TL) para a inclusão do íon Dy como dopante e Li como co-dopante, aumentando a eficiência TL da mesma. Pelo método de fusão e moldagem, foram obtidos amostras vítreas e vitrocerâmicas. A fase cristalina presente nas amostras vitrocerâmicas foi determinada por difratometria de raios X e identificada como fase única CaB2O4. A composição vitrocerâmica 20CaB4 (% em massa) apresentou a melhor resposta TL, sendo dopada com Dy e co-dopada com Li para o estudo das propriedades dosimétricas. Este estudo mostrou uma resposta linear num intervalo de 5 a 70 minutos de exposição à radiação ultravioleta e uma boa reprodutibilidade do sinal TL provando ser um material promissor para a utilização em dosimetria pessoal e clínica.
Title in English
Thermal and sctructural properties of the CaB4O7-CaB2O4 system viewing the development of thermoluminescent dosimeter
Keywords in English
Borate
Dosimetry
Thermal properties
Thermoluminescence
Abstract in English
Borate glasses containing modified oxides have been studied on account of their effective atomic number close to that of the human tissue, what makes them interesting materials for the development of the thermoluminescent dosimeters. The purpose of this work was to study the thermal and structure properties of the xCaB4O7-(100-x)CaB2O4 system with x ranging from 0 to 100 wt%. The undoped samples were previously studied in order to determine a composition that would present a better thermoluminescent response for the incluision of the Dy íon as dopant and Li as co-dopant, thus increasing its TL efficiency. By the melting/molding method, the glass-ceramic samples was determined by the X-ray difractometry and identified as a unique CaB2O4 phase. The glass-ceramic 20 CaB2O4 (wt%) composition presented the best TL response being doped with Dy and co-doped with Li for the study of the dosimetric properties. This study has shown a linear response within an interval of 5 to 70 minutes of exposure to the UV radiation and good reproducibility of the TL signal, thus proving to be a promising material for using in the personal and clinical dosimetry.
 
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SeilaRojas.pdf (1,023.02 Kbytes)
Publishing Date
2007-09-21
 
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