Detalhes bibliográficos
| Ano de defesa: |
2023 |
| Autor(a) principal: |
MELO, Glauco Hebert Almeida de
 |
| Orientador(a): |
STEIMACHER, Alysson
|
| Banca de defesa: |
STEIMACHER, Alysson
,
PEDROCHI, Franciana
,
BARBOZA, Marcio José
,
LODI, Thiago Augusto
,
MEDINA NETO, Antonio |
| Tipo de documento: |
Tese
|
| Tipo de acesso: |
Acesso aberto |
| Idioma: |
por |
| Instituição de defesa: |
Universidade Federal do Maranhão
|
| Programa de Pós-Graduação: |
PROGRAMA DE PÓS-GRADUAÇÃO EM CIÊNCIA DOS MATERIAIS/CCSST
|
| Departamento: |
COORDENACAO DO CURSO DE LICENCIATURAS EM CIENCIAS NATURAIS IMPERATRIZ/CCSST
|
| País: |
Brasil
|
| Palavras-chave em Português: |
|
| Palavras-chave em Inglês: |
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| Área do conhecimento CNPq: |
|
| Link de acesso: |
https://tedebc.ufma.br/jspui/handle/tede/4960
|
Resumo: |
The zinc borophosphate is a glass system prepared with relatively low-cost raw materials and low melting temperatures when compared to silicate glasses, for example. In this work samples were produced in different regions of the ternary diagram of the ZnO – P2O5 – B2O3 system. A composition range of the diagram was chosen to study the effects of replacing P2O5 by ZnO. Thermal, structural, and optical properties were evaluated as a function of zinc concentration. It was observed that the replacement of P2O5 by ZnO promotes the depolymerization of boron and phosphorus structures present in the glass. Consequently, changes were observed in almost all investigated properties. Attenuation parameters of these samples were calculated and compared with commercial materials and other lead-based glasses. It was found that glasses with a higher zinc content have better indicators for use in radiation attenuation. The x-ray diffractograms shows that the produced material is amorphous. One of these samples was chosen to study Tb4O7 and Eu2O3 doping as well as Tb4O7/Eu2O3 co-doping. The luminescence of the samples was investigated at room temperature under excitation at 375 nm, 394 nm and 405 nm and varying the temperature up to 480 K under excitation at 375 nm. The coordinates in the chromaticity diagram were calculated and presented in the CIE 1931 diagram. The lifetime was calculated for the emission at 545 nm and the energy transfer parameters were determined. In the luminescence studies, characteristic absorptions and emissions of Tb3+ and Eu3+ ions were observed. In the chromaticity diagram it was possible to observe significant changes in the color of the samples when exciting co-doped samples at different wavelengths as well with Eu2O3 content. In the simulation of the composition with LED in the blue region, the obtaining tunable white light war verified. The emission intensity of samples is reduced with increasing temperature for practically all wavelengths. The radiative lifetime shows a reduction with the Eu2O3 content and there is an increase in the probability of energy transfer. The set of results suggest that the glass system studied in this work is an excellent option for use in high-energy radiation attenuation as well as a rare-earth host for luminescence applications. |
