Simulação computacional de tungstatos tipo Scheelita para aplicações ópticas
Autor(a) principal: | |
---|---|
Data de Publicação: | 2013 |
Tipo de documento: | Tese |
Idioma: | por |
Título da fonte: | Repositório Institucional da UFS |
Texto Completo: | https://ri.ufs.br/handle/riufs/5304 |
Resumo: | The scheelite type tungstates MWO4 have been studied for a long time due to their optical properties. The main property is the luminescence, both intrinsic and extrinsic (when doped with trivalent lanthanide ions, Ln3+). Another group of scheelite- typed are the double tungstates, ALn(WO4)2. The main feature of these tungstates is a structural disorder involving a random distribution of the ions A (alkali metals) and Ln in the crystal lattice that may influence the luminescence of the material. In literature there are several models to explain both intrinsic and extrinsic luminescence, as recombination of self-trapped excitons, MO and/or WO3 vacancies, stoichiometry deviation, other phases, oxygen at interstitial site, oxygen vacancies and M ion vacancies. As the main technology applications associated with these tungstates are such optics fiber, solid state lasers, scintillators in detectors and recently as white LEDs, it is necessary to better understand and possibly solve or dominate the many physical problems that surround them. Then, using computer simulation based on a model in which the ions are treated as charged spheres interacting through interaction potentials which aim to minimize the lattice energy, tungstates have their perfect and defective crystal lattices simulated to try to elucidate the defect mechanism that dominates and/or contributes for luminescence and its consequences. Using static computer simulation we have as main results: a) 21 different tungstates were modeled using a single set of potential parameters taking into account the covalency of the (WO4)2- group. This covalent interaction affects the behavior of defects, where (WO4)2- groups can be directly connected by an oxygen ion at an interstitial site; b) the charge compensation for extrinsic defects is via interstitial oxygen. When codoped, the codopant ionic radius directly influences the solution energy; c) the simulated energy levels for SrWO4:Eu3+ were compared with recent experimental studies and are in agreement, pointing two different symmetries to the Eu site and d) simulation of holes and electrons in these tungstates reveals that n-type conductivity is expected. |
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Amaral, Jomar Batistahttp://lattes.cnpq.br/9710589741627606Valério, Mário Ernesto Giroldohttp://lattes.cnpq.br/15038029715539862017-09-26T18:27:18Z2017-09-26T18:27:18Z2013-03-01https://ri.ufs.br/handle/riufs/5304The scheelite type tungstates MWO4 have been studied for a long time due to their optical properties. The main property is the luminescence, both intrinsic and extrinsic (when doped with trivalent lanthanide ions, Ln3+). Another group of scheelite- typed are the double tungstates, ALn(WO4)2. The main feature of these tungstates is a structural disorder involving a random distribution of the ions A (alkali metals) and Ln in the crystal lattice that may influence the luminescence of the material. In literature there are several models to explain both intrinsic and extrinsic luminescence, as recombination of self-trapped excitons, MO and/or WO3 vacancies, stoichiometry deviation, other phases, oxygen at interstitial site, oxygen vacancies and M ion vacancies. As the main technology applications associated with these tungstates are such optics fiber, solid state lasers, scintillators in detectors and recently as white LEDs, it is necessary to better understand and possibly solve or dominate the many physical problems that surround them. Then, using computer simulation based on a model in which the ions are treated as charged spheres interacting through interaction potentials which aim to minimize the lattice energy, tungstates have their perfect and defective crystal lattices simulated to try to elucidate the defect mechanism that dominates and/or contributes for luminescence and its consequences. Using static computer simulation we have as main results: a) 21 different tungstates were modeled using a single set of potential parameters taking into account the covalency of the (WO4)2- group. This covalent interaction affects the behavior of defects, where (WO4)2- groups can be directly connected by an oxygen ion at an interstitial site; b) the charge compensation for extrinsic defects is via interstitial oxygen. When codoped, the codopant ionic radius directly influences the solution energy; c) the simulated energy levels for SrWO4:Eu3+ were compared with recent experimental studies and are in agreement, pointing two different symmetries to the Eu site and d) simulation of holes and electrons in these tungstates reveals that n-type conductivity is expected.Os tungstatos tipo scheelita MWO4 vêm sendo estudados há bastante tempo devido às suas propriedades ópticas. A principal é a luminescência, tanto intrínseca quanto extrínseca (quando dopados com íons lantanídeos trivalentes, Ln3+). Outro grupo de tungstatos tipo scheelita são os duplos, ALn(WO4)2. A principal característica deste tungstatos é uma desordem estrutural, envolvendo uma distribuição aleatória dos íons A (metais alcalinos) e Ln na rede que pode influenciar a luminescência deste material. Na literatura há diversos modelos para explicar tanto a luminescência intrínseca quanto a extrínseca, como recombinação de éxcitons auto-armadilhados, vacâncias de MO e/ou WO3, desvio de estequiometria, outras fases, oxigênio em um sítio intersticial e vacâncias de oxigênio e vacâncias do íon M. Como as principais aplicações tecnológicas associadas a estes tungstatos, são como fibras ópticas, lasers do estado sólido, cintiladores em detectores e recentemente como LEDs brancos, faz-se necessário entender melhor e se possível solucionar ou dominar os diversos problemas físicos que os cercam. Então, usando simulação computacional baseada em um modelo em que os íons são considerados como esferas carregadas interagindo entre si através de potenciais de interação que visam minimizar a energia da rede, os tungstatos têm suas redes cristalinas perfeitas e defeituosas simuladas para procurar elucidar o mecanismo de defeito que domina(m) e/ou contribui(em) para a luminescência e quais suas consequências. Usando a simulação computacional estática temos como principais resultados: a) 21 tungstatos diferentes foram modelados usando um único conjunto de parâmetros dos potenciais levando em conta a covalência do grupo (WO4)2-. Esta interação covalente afeta o comportamento dos defeitos, onde grupos de (WO4)2- podem ser diretamente ligados por um íon de oxigênio em um sítio intersticial; b) a compensação de cargas para defeitos extrínsecos é via oxigênio intersticial. Quando codopados, o raio iônico do codopante influencia diretamente na energia de solução; c) os níveis de energia simulados para o SrWO4:Eu3+ e comparados com trabalhos experimentais recentes estão em acordo, apontando duas simetrias diferentes para o sítio de Eu e d) a simulação de buracos e elétrons nestes tungstatos revela que condutividade tipo n é esperada.application/pdfporLuminescênciaPropriedades ópticasTungstatos tipo ScheelitaScheelitaSimulação computacional,ÓpticaComputer simulationScheeliteTungsten mines and miningScheelite type- tungstatesCNPQ::CIENCIAS EXATAS E DA TERRA::FISICASimulação computacional de tungstatos tipo Scheelita para aplicações ópticasinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/doctoralThesisPós-Graduação em Físicainfo:eu-repo/semantics/openAccessreponame:Repositório Institucional da UFSinstname:Universidade Federal de Sergipe (UFS)instacron:UFSORIGINALJOMAR_BATISTA_AMARAL.pdfapplication/pdf7655754https://ri.ufs.br/jspui/bitstream/riufs/5304/1/JOMAR_BATISTA_AMARAL.pdfdce72b25e7b472a9e316d07a0435b2cfMD51TEXTJOMAR_BATISTA_AMARAL.pdf.txtJOMAR_BATISTA_AMARAL.pdf.txtExtracted texttext/plain247244https://ri.ufs.br/jspui/bitstream/riufs/5304/2/JOMAR_BATISTA_AMARAL.pdf.txtf73b4e4a902a8fb08ab531f983d4af48MD52THUMBNAILJOMAR_BATISTA_AMARAL.pdf.jpgJOMAR_BATISTA_AMARAL.pdf.jpgGenerated Thumbnailimage/jpeg1464https://ri.ufs.br/jspui/bitstream/riufs/5304/3/JOMAR_BATISTA_AMARAL.pdf.jpg53c6f5c09cf2f43378ad4feb9fa80959MD53riufs/53042019-07-30 19:18:03.689oai:ufs.br:riufs/5304Repositório InstitucionalPUBhttps://ri.ufs.br/oai/requestrepositorio@academico.ufs.bropendoar:2019-07-30T22:18:03Repositório Institucional da UFS - Universidade Federal de Sergipe (UFS)false |
dc.title.por.fl_str_mv |
Simulação computacional de tungstatos tipo Scheelita para aplicações ópticas |
title |
Simulação computacional de tungstatos tipo Scheelita para aplicações ópticas |
spellingShingle |
Simulação computacional de tungstatos tipo Scheelita para aplicações ópticas Amaral, Jomar Batista Luminescência Propriedades ópticas Tungstatos tipo Scheelita Scheelita Simulação computacional, Óptica Computer simulation Scheelite Tungsten mines and mining Scheelite type- tungstates CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA |
title_short |
Simulação computacional de tungstatos tipo Scheelita para aplicações ópticas |
title_full |
Simulação computacional de tungstatos tipo Scheelita para aplicações ópticas |
title_fullStr |
Simulação computacional de tungstatos tipo Scheelita para aplicações ópticas |
title_full_unstemmed |
Simulação computacional de tungstatos tipo Scheelita para aplicações ópticas |
title_sort |
Simulação computacional de tungstatos tipo Scheelita para aplicações ópticas |
author |
Amaral, Jomar Batista |
author_facet |
Amaral, Jomar Batista |
author_role |
author |
dc.contributor.author.fl_str_mv |
Amaral, Jomar Batista |
dc.contributor.advisor1Lattes.fl_str_mv |
http://lattes.cnpq.br/9710589741627606 |
dc.contributor.advisor1.fl_str_mv |
Valério, Mário Ernesto Giroldo |
dc.contributor.authorLattes.fl_str_mv |
http://lattes.cnpq.br/1503802971553986 |
contributor_str_mv |
Valério, Mário Ernesto Giroldo |
dc.subject.por.fl_str_mv |
Luminescência Propriedades ópticas Tungstatos tipo Scheelita Scheelita Simulação computacional, Óptica |
topic |
Luminescência Propriedades ópticas Tungstatos tipo Scheelita Scheelita Simulação computacional, Óptica Computer simulation Scheelite Tungsten mines and mining Scheelite type- tungstates CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA |
dc.subject.eng.fl_str_mv |
Computer simulation Scheelite Tungsten mines and mining Scheelite type- tungstates |
dc.subject.cnpq.fl_str_mv |
CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA |
description |
The scheelite type tungstates MWO4 have been studied for a long time due to their optical properties. The main property is the luminescence, both intrinsic and extrinsic (when doped with trivalent lanthanide ions, Ln3+). Another group of scheelite- typed are the double tungstates, ALn(WO4)2. The main feature of these tungstates is a structural disorder involving a random distribution of the ions A (alkali metals) and Ln in the crystal lattice that may influence the luminescence of the material. In literature there are several models to explain both intrinsic and extrinsic luminescence, as recombination of self-trapped excitons, MO and/or WO3 vacancies, stoichiometry deviation, other phases, oxygen at interstitial site, oxygen vacancies and M ion vacancies. As the main technology applications associated with these tungstates are such optics fiber, solid state lasers, scintillators in detectors and recently as white LEDs, it is necessary to better understand and possibly solve or dominate the many physical problems that surround them. Then, using computer simulation based on a model in which the ions are treated as charged spheres interacting through interaction potentials which aim to minimize the lattice energy, tungstates have their perfect and defective crystal lattices simulated to try to elucidate the defect mechanism that dominates and/or contributes for luminescence and its consequences. Using static computer simulation we have as main results: a) 21 different tungstates were modeled using a single set of potential parameters taking into account the covalency of the (WO4)2- group. This covalent interaction affects the behavior of defects, where (WO4)2- groups can be directly connected by an oxygen ion at an interstitial site; b) the charge compensation for extrinsic defects is via interstitial oxygen. When codoped, the codopant ionic radius directly influences the solution energy; c) the simulated energy levels for SrWO4:Eu3+ were compared with recent experimental studies and are in agreement, pointing two different symmetries to the Eu site and d) simulation of holes and electrons in these tungstates reveals that n-type conductivity is expected. |
publishDate |
2013 |
dc.date.issued.fl_str_mv |
2013-03-01 |
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2017-09-26T18:27:18Z |
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