Detalhes bibliográficos
| Ano de defesa: |
2021 |
| Autor(a) principal: |
DANTAS, Natacya Fontes
 |
| Orientador(a): |
STEIMACHER, Alysson
|
| Banca de defesa: |
STEIMACHER, Alysson
,
PEDROCHI, Franciana
,
SAKAI, Otávio Akira
|
| Tipo de documento: |
Dissertação
|
| 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: |
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| Link de acesso: |
https://tedebc.ufma.br/jspui/handle/tede/5175
|
Resumo: |
In this work the optical and spectroscopic properties of ZnPBAl Dy-doped and Dy:Sm-codoped glasses were studied. The samples were prepared by the melting-quenching method and can be classified in two sample series: the ZnPBAl glasses doped with different concentrations of Dy2O3 and the ZnPBAl glasses with different concentrations of Dy2O3 and fixed concentration of Sm2O3. The changes in optical properties by codoping and the possibility of energy transfer from Dy3+ to Sm3+ ions were investigated. The amorphous nature of the glasses was confirmed by DRX results. The partial substitution of ZnO by the Dy2O3 and Sm2O3 resulted in an increase of density and molar volume of the glasses due to the changes caused in the glass structure, but the values of refractive index and electronic polarizability were not affected by these changes. The FTIR spectra revealed groups of tetrahedral phosphate in Q0 and Q2 conformations. The absorption spectra of the glasses revealed absorption bands of Dy3+ and Sm3+ ions from the fundamental states 6H15/2 and 6H5/2 to more energetic states and the increasing of Dy3+ bands intensity. The excitation source in 350 nm was chosen based on the excitation spectra of the doped Dy3+ and Sm3+ samples. The emission bands of the rare earths ions studied were observed in the luminescence results and the comparison of the 0,25Sm and 0,25Sm:0,25Dy samples suggested the energy transfer between Dy3+ and Sm3+ ions, which was confirmed by the calculation of efficiency transfer (η) from the lifetime data (τ).The luminescence results under 405 nm excitation revealed the increase of Dy3+ emission bands (doped glasses) and the decrease of Sm3+ emission bands (codoped glasses). The chromaticity diagram CIE 1931 of doped and codoped ZnPBAl glasses shows the color coordinates into the yellowish-white region with color temperatures close to that of natural light. The obtained results suggest that Dy-doped and Dy3+:Sm3+ -codoped ZnPBAl glasses are candidates for white emitting devices application, such as W-LEDs. |
