Otimização do tempo de tratamento térmico de nonocristais core e core-shell de LaF3 dopados com íons terra raras
Autor(a) principal: | |
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Data de Publicação: | 2016 |
Tipo de documento: | Dissertação |
Idioma: | por |
Título da fonte: | Repositório Institucional da Universidade Federal de Alagoas (UFAL) |
Texto Completo: | http://www.repositorio.ufal.br/handle/riufal/2337 |
Resumo: | In this work, we investigated the annealing time optimization of core and core-shell LaF3 nanocrystals doped and co-dopados with rare earth ions. To this, several sets of LaF3 samples were synthesized and submitted to thermal treatment (TT) at 500oC for different times [0 (no TT), 5, 10, 30, 90, and 180 minutes]. Structural characterizations using x-ray diffraction, FTIR, and Raman spectroscopy were carried out, and optical characterization by means of luminescence. It was observed that the TT does not change the hexagonal phase of LaF3; the diffraction peaks are enhanced due to crystallinity improvement; and impurities of hydroxyl groups (O-H) and of H2O molecules are significantly reduced. In the core samples, these O-H and H2O vibration modes are more reduced for 180 minutes of TT. However, for the Yb/Er co-doped core and core-shell samples, little or almost no difference was observed in the FTIR results for TT times from 30 minutes. Regarding the optical properties, the emissions increased significantly with the time of TT for all the investigated samples, although with different behaviors. The core-shell samples with Yb3+ in the shell, even those ones with a second undoped shell, showed a reduction in the emissions for 180 minutes of TT compared to those for 90 minutes of TT. This is an indication of the TT effect on the surface making the Yb3+ ion, which is an excellent energy donor, interacts more with the surface of the nanocrystals. On the other hand, the samples only core, co-doped with Yb/Er, exhibited similar emission for TT of 90 and 180 minutes, most likely because there is less competition between the energy transfer from Yb3+ to Er3+ than from Yb3+ to surface impurities. We can say, therefore, that the optimized time of TT at 500 oC is 90 minutes, including for the near-infrared emission from Er3+ ions at 1550 nm. In relation to the Eu3+ doped samples, the best TT times were: from 30 minutes for core samples and 180 minutes for core-shell. For Nd3+ doped samples, the core-shell showed a more regular evolution, likely due to the shielding effect of the shell. It was also noted the similarity of the emission intensities for samples under TT for 90 and 180 minutes for both set of samples (core and core-shell). Therefore, the TT at 500 oC during 90 minutes is sufficient to obtain the desired effect of removing impurities and increasing the Nd3+ emission. Finally, it is important to say that other measures are necessary for a better understanding of what is occurring on the surfaces of nanoparticles and they should be done soon. |
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Otimização do tempo de tratamento térmico de nonocristais core e core-shell de LaF3 dopados com íons terra rarasOptimization of the thermal treatment time of nanocrystals core and core-shell of LaF3 doped with rare land ionsNanopartículasLuminescênciaCore-shell – Tratamento térmicoNanoparticlesLuminescenceAnnealingCore-shellCNPQ::CIENCIAS EXATAS E DA TERRA::FISICA::FISICA DA MATERIA CONDENSADAIn this work, we investigated the annealing time optimization of core and core-shell LaF3 nanocrystals doped and co-dopados with rare earth ions. To this, several sets of LaF3 samples were synthesized and submitted to thermal treatment (TT) at 500oC for different times [0 (no TT), 5, 10, 30, 90, and 180 minutes]. Structural characterizations using x-ray diffraction, FTIR, and Raman spectroscopy were carried out, and optical characterization by means of luminescence. It was observed that the TT does not change the hexagonal phase of LaF3; the diffraction peaks are enhanced due to crystallinity improvement; and impurities of hydroxyl groups (O-H) and of H2O molecules are significantly reduced. In the core samples, these O-H and H2O vibration modes are more reduced for 180 minutes of TT. However, for the Yb/Er co-doped core and core-shell samples, little or almost no difference was observed in the FTIR results for TT times from 30 minutes. Regarding the optical properties, the emissions increased significantly with the time of TT for all the investigated samples, although with different behaviors. The core-shell samples with Yb3+ in the shell, even those ones with a second undoped shell, showed a reduction in the emissions for 180 minutes of TT compared to those for 90 minutes of TT. This is an indication of the TT effect on the surface making the Yb3+ ion, which is an excellent energy donor, interacts more with the surface of the nanocrystals. On the other hand, the samples only core, co-doped with Yb/Er, exhibited similar emission for TT of 90 and 180 minutes, most likely because there is less competition between the energy transfer from Yb3+ to Er3+ than from Yb3+ to surface impurities. We can say, therefore, that the optimized time of TT at 500 oC is 90 minutes, including for the near-infrared emission from Er3+ ions at 1550 nm. In relation to the Eu3+ doped samples, the best TT times were: from 30 minutes for core samples and 180 minutes for core-shell. For Nd3+ doped samples, the core-shell showed a more regular evolution, likely due to the shielding effect of the shell. It was also noted the similarity of the emission intensities for samples under TT for 90 and 180 minutes for both set of samples (core and core-shell). Therefore, the TT at 500 oC during 90 minutes is sufficient to obtain the desired effect of removing impurities and increasing the Nd3+ emission. Finally, it is important to say that other measures are necessary for a better understanding of what is occurring on the surfaces of nanoparticles and they should be done soon.Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorNesta dissertação investigamos a otimização do tempo de tratamento térmico (TT) de nanocristais core e core-shell de LaF3 dopados e co-dopados com íons terras-raras. Para isso foram sintetizados vários conjuntos de amostras e submetidos a TT em 500oC por diferentes tempos [0 (sem TT), 5, 10, 30, 90 e 180 minutos]. Caracterizações estruturais usando difração de raios-X, FTIR e espectroscopia Raman foram realizadas, e ópticas por meio de luminescência. Foi observado que o TT não muda a fase hexagonal do LaF3; os picos de difração são intensificados devido ao melhoramento da cristalinidade; e impurezas de hidroxilas O-H e moléculas de H2O são significativamente reduzidas. Nas amostras core foi observado que os modos de vibração de O-H e H2O diminuem mais no tempo de TT de 180 minutos. No entanto, nas amostras core-shell co-dopadas com Yb/Er, pouca ou quase nenhuma diferença foi observada nos resultados de FTIR para tempos de TT a partir de 30 minutos. Em relação as propriedades ópticas, as emissões aumentam significativamente com o tempo de TT para todas as amostras estudadas, embora com comportamentos distintos. As amostras core-shell com Yb3+ no shell, mesmo aquelas com uma segunda camada não dopada, apresentaram uma redução nas emissões para o TT por 180 minutos em comparação com 90 minutos. Isso é uma indicação do efeito do TT na superfície fazendo o íon Yb3+, que é um excelente doador de energia, interagir mais com a superfície das nanopartículas. Por outro lado, as amostras somente core co-dopadas com Er/Yb apresentaram emissão parecida nos tempos de TT de 90 e 180 minutos, provavelmente por existir uma competição menor entre as transferências de energias do Yb3+ para o Er3+ que do Yb3+ para as impurezas de superfície. Podemos afirmar, portanto, que o tempo otimizado de TT em 500oC é 90 minutos, inclusive para as emissões no infravermelho próximo do Er3+ em 1550 nm. Já as amostras dopadas com Eu3+, os melhores tempos de TT foram: a partir de 30 minutos para amostras core e 180 minutos para core-shell. Para as amostras dopadas com Nd3+, as core-shell apresentaram uma evolução mais regular, provavelmente devido à blindagem do shell. Também foi notável a similaridade das intensidades dos espectros para as amostras TT em 90 e 180 minutos para ambos os conjuntos (core e core-shell). Portanto, o TT em 500 oC por 90 min é suficiente para obter o efeito desejado de eliminação de impurezas e aumento das emissões do íon Nd3+. Por fim, é importante dizer que outras medidas são necessárias para uma melhor compreensão do que está ocorrendo nas superfícies das nanopartículas e devem ser feitas em breve.Universidade Federal de AlagoasBrasilPrograma de Pós-Graduação em Física da Matéria CondensadaUFALSilva, Carlos Jacinto dahttp://lattes.cnpq.br/5196560719753785Silva , Wagner Ferreira dahttp://lattes.cnpq.br/4219887347412130Amorim, Heron Teixeirahttp://lattes.cnpq.br/0557895881671394Vermelho, Marcos Vínicius Diashttp://lattes.cnpq.br/2876196606157039Sousa , Michael Ronnes Medeiros de2018-01-23T17:48:35Z2017-11-302018-01-23T17:48:35Z2016-03-30info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/masterThesisapplication/pdfSOUSA, Michael Ronnes Medeiros de. Otimização do tempo de tratamento térmico de nonocristais core e core-shell de LaF3 dopados com íons terra raras. 2016. 80 f. Dissertação (Mestrado em Física da Matéria Condensada) – Instituto de Física, Programa de Pós-Graduação em Física da Matéria Condensada, Universidade Federal de Alagoas, Maceió, 2016.http://www.repositorio.ufal.br/handle/riufal/2337porinfo:eu-repo/semantics/openAccessreponame:Repositório Institucional da Universidade Federal de Alagoas (UFAL)instname:Universidade Federal de Alagoas (UFAL)instacron:UFAL2019-01-09T21:52:04Zoai:www.repositorio.ufal.br:riufal/2337Repositório InstitucionalPUBhttp://www.repositorio.ufal.br/oai/requestri@sibi.ufal.bropendoar:2019-01-09T21:52:04Repositório Institucional da Universidade Federal de Alagoas (UFAL) - Universidade Federal de Alagoas (UFAL)false |
dc.title.none.fl_str_mv |
Otimização do tempo de tratamento térmico de nonocristais core e core-shell de LaF3 dopados com íons terra raras Optimization of the thermal treatment time of nanocrystals core and core-shell of LaF3 doped with rare land ions |
title |
Otimização do tempo de tratamento térmico de nonocristais core e core-shell de LaF3 dopados com íons terra raras |
spellingShingle |
Otimização do tempo de tratamento térmico de nonocristais core e core-shell de LaF3 dopados com íons terra raras Sousa , Michael Ronnes Medeiros de Nanopartículas Luminescência Core-shell – Tratamento térmico Nanoparticles Luminescence Annealing Core-shell CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA::FISICA DA MATERIA CONDENSADA |
title_short |
Otimização do tempo de tratamento térmico de nonocristais core e core-shell de LaF3 dopados com íons terra raras |
title_full |
Otimização do tempo de tratamento térmico de nonocristais core e core-shell de LaF3 dopados com íons terra raras |
title_fullStr |
Otimização do tempo de tratamento térmico de nonocristais core e core-shell de LaF3 dopados com íons terra raras |
title_full_unstemmed |
Otimização do tempo de tratamento térmico de nonocristais core e core-shell de LaF3 dopados com íons terra raras |
title_sort |
Otimização do tempo de tratamento térmico de nonocristais core e core-shell de LaF3 dopados com íons terra raras |
author |
Sousa , Michael Ronnes Medeiros de |
author_facet |
Sousa , Michael Ronnes Medeiros de |
author_role |
author |
dc.contributor.none.fl_str_mv |
Silva, Carlos Jacinto da http://lattes.cnpq.br/5196560719753785 Silva , Wagner Ferreira da http://lattes.cnpq.br/4219887347412130 Amorim, Heron Teixeira http://lattes.cnpq.br/0557895881671394 Vermelho, Marcos Vínicius Dias http://lattes.cnpq.br/2876196606157039 |
dc.contributor.author.fl_str_mv |
Sousa , Michael Ronnes Medeiros de |
dc.subject.por.fl_str_mv |
Nanopartículas Luminescência Core-shell – Tratamento térmico Nanoparticles Luminescence Annealing Core-shell CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA::FISICA DA MATERIA CONDENSADA |
topic |
Nanopartículas Luminescência Core-shell – Tratamento térmico Nanoparticles Luminescence Annealing Core-shell CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA::FISICA DA MATERIA CONDENSADA |
description |
In this work, we investigated the annealing time optimization of core and core-shell LaF3 nanocrystals doped and co-dopados with rare earth ions. To this, several sets of LaF3 samples were synthesized and submitted to thermal treatment (TT) at 500oC for different times [0 (no TT), 5, 10, 30, 90, and 180 minutes]. Structural characterizations using x-ray diffraction, FTIR, and Raman spectroscopy were carried out, and optical characterization by means of luminescence. It was observed that the TT does not change the hexagonal phase of LaF3; the diffraction peaks are enhanced due to crystallinity improvement; and impurities of hydroxyl groups (O-H) and of H2O molecules are significantly reduced. In the core samples, these O-H and H2O vibration modes are more reduced for 180 minutes of TT. However, for the Yb/Er co-doped core and core-shell samples, little or almost no difference was observed in the FTIR results for TT times from 30 minutes. Regarding the optical properties, the emissions increased significantly with the time of TT for all the investigated samples, although with different behaviors. The core-shell samples with Yb3+ in the shell, even those ones with a second undoped shell, showed a reduction in the emissions for 180 minutes of TT compared to those for 90 minutes of TT. This is an indication of the TT effect on the surface making the Yb3+ ion, which is an excellent energy donor, interacts more with the surface of the nanocrystals. On the other hand, the samples only core, co-doped with Yb/Er, exhibited similar emission for TT of 90 and 180 minutes, most likely because there is less competition between the energy transfer from Yb3+ to Er3+ than from Yb3+ to surface impurities. We can say, therefore, that the optimized time of TT at 500 oC is 90 minutes, including for the near-infrared emission from Er3+ ions at 1550 nm. In relation to the Eu3+ doped samples, the best TT times were: from 30 minutes for core samples and 180 minutes for core-shell. For Nd3+ doped samples, the core-shell showed a more regular evolution, likely due to the shielding effect of the shell. It was also noted the similarity of the emission intensities for samples under TT for 90 and 180 minutes for both set of samples (core and core-shell). Therefore, the TT at 500 oC during 90 minutes is sufficient to obtain the desired effect of removing impurities and increasing the Nd3+ emission. Finally, it is important to say that other measures are necessary for a better understanding of what is occurring on the surfaces of nanoparticles and they should be done soon. |
publishDate |
2016 |
dc.date.none.fl_str_mv |
2016-03-30 2017-11-30 2018-01-23T17:48:35Z 2018-01-23T17:48:35Z |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/masterThesis |
format |
masterThesis |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
SOUSA, Michael Ronnes Medeiros de. Otimização do tempo de tratamento térmico de nonocristais core e core-shell de LaF3 dopados com íons terra raras. 2016. 80 f. Dissertação (Mestrado em Física da Matéria Condensada) – Instituto de Física, Programa de Pós-Graduação em Física da Matéria Condensada, Universidade Federal de Alagoas, Maceió, 2016. http://www.repositorio.ufal.br/handle/riufal/2337 |
identifier_str_mv |
SOUSA, Michael Ronnes Medeiros de. Otimização do tempo de tratamento térmico de nonocristais core e core-shell de LaF3 dopados com íons terra raras. 2016. 80 f. Dissertação (Mestrado em Física da Matéria Condensada) – Instituto de Física, Programa de Pós-Graduação em Física da Matéria Condensada, Universidade Federal de Alagoas, Maceió, 2016. |
url |
http://www.repositorio.ufal.br/handle/riufal/2337 |
dc.language.iso.fl_str_mv |
por |
language |
por |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
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openAccess |
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application/pdf |
dc.publisher.none.fl_str_mv |
Universidade Federal de Alagoas Brasil Programa de Pós-Graduação em Física da Matéria Condensada UFAL |
publisher.none.fl_str_mv |
Universidade Federal de Alagoas Brasil Programa de Pós-Graduação em Física da Matéria Condensada UFAL |
dc.source.none.fl_str_mv |
reponame:Repositório Institucional da Universidade Federal de Alagoas (UFAL) instname:Universidade Federal de Alagoas (UFAL) instacron:UFAL |
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Universidade Federal de Alagoas (UFAL) |
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UFAL |
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UFAL |
reponame_str |
Repositório Institucional da Universidade Federal de Alagoas (UFAL) |
collection |
Repositório Institucional da Universidade Federal de Alagoas (UFAL) |
repository.name.fl_str_mv |
Repositório Institucional da Universidade Federal de Alagoas (UFAL) - Universidade Federal de Alagoas (UFAL) |
repository.mail.fl_str_mv |
ri@sibi.ufal.br |
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