Detalhes bibliográficos
| Ano de defesa: |
2021 |
| Autor(a) principal: |
LIMA, Brenda Gomes Silva de
 |
| Orientador(a): |
BARBOZA, Marcio José
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| Banca de defesa: |
BARBOZA, Marcio José
,
PEDROCHI, Franciana
,
SANDRINI, Marcelo
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| Tipo de documento: |
Dissertação
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| 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: |
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| Palavras-chave em Inglês: |
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| Área do conhecimento CNPq: |
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| Link de acesso: |
https://tedebc.ufma.br/jspui/handle/tede/3663
|
Resumo: |
Pr3+ doped calcium boroaluminate (CaBAl) glasses were synthesized and characterized. Samples with composition (25-x)CaO-50B2O3-15Al2O3-10CaF2-xPr6O11, varying x from 0.25 to 2.0 % wt, were synthesized by melting-quenching method, in air atmosphere furnaces, aiming understanding how the dopant changes the structural, thermal, spectroscopic and optical properties. X-ray diffraction confirmed the amorphous nature of the studied glasses and proved the addition of Pr3+ up to 2% wt, did not induce crystallization of the glass. The values of volumetric density and molar volume increased as a function of Pr3+ content. The FTIR spectrum showed characteristic bands of CaBAl glasses and revealed there is no conversion of units BO3⟷BO4, with until 2% Pr6O11.In the analysis of DTA, it was observed that the Tg and Tx values did not change significantly with Pr6O11 concentrations. The refractive index and the electronic polarizability of the glasses increased with Pr6O11 concentrations. The absorption coefficient bands showed characteristic transitions of Pr3+, in the visible and in the infrared regions, which are transitions from the 3H4 ground state to the excited energy levels. The band gap decreased with the increase Pr6O11 concentration. Excitation spectra showed that 3H4→3P2 (444 nm) transition has gained maximum intensity as compared to other transitions and it was selected as excitation wavelength. The luminescence spectrum showed the highest emission intensity at 601 nm, 1D2→3H4 transition, and concentration quenching was observed for concentrations higher than 1.5 wt% of Pr3+. The CIE diagram demonstrated that the samples emissions occur in the orange region. The lifetime, for the 1D2 level, decreases with increasing of Pr3+ concentration, due Pr3+ -Pr3+ interaction. The results obtained suggest that the synthesized and characterized glasses have potential for applications in photonic devices in the orange region. |
