Estudo teórico das propriedades estruturais, eletrônicas e ópticas dos compostos Bi4Ge3O12 e Bi4Si3O12
Autor(a) principal: | |
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Data de Publicação: | 2016 |
Tipo de documento: | Dissertação |
Idioma: | por |
Título da fonte: | Repositório Institucional da UFS |
Texto Completo: | https://ri.ufs.br/handle/riufs/5361 |
Resumo: | This dissertation presents a theoretical study, based on density functional theory (DFT), upon structural, electronic and optical properties of Bi4Ge3O12 (Bismuth germanate, BGO) and Bi4Si3O12 (Bismuth silicate, BSO) compounds. As a computational tool it was utilized Full Potential Linear Augmented Plane Wave Method (FPLAPW), implemented into WIEN2k computer code and considered as one of the most precise tools for electronic structure calculations of solid materials. Exchange and correlation e ects were simulated by LDA, GGA-PBEsol, BJ, mBJ-original, mBJ P-present and mBJ P-semiconductor functionals. Lattice parameters and all atomic positions within the BGO and BSO unit cells were computationally optimized in order to reach minimum energy con guration. The resulting structural parameters showed good agreement with experimental data. The results of electronic structure calculations (band structure and density of electron states DOS) were best tted to experiment while using the mBJ P-semiconductor functional. They revealed a nature and size of the compound's fundamental band gaps, as well as predominant orbital character of bands around it. According to the results, the BGO and BSO have indirect fundamental gaps of 5.05 and 5.36 eV in excellent concordance with the experimental value 5.0 eV (BGO) and 5.4 eV (BSO). For both compounds the valence band top is dominated by the O 2p-states, with non-negligible amount of the Bi 6s-states, while the conduction band bottom is consisted mostly of the Bi 6p-states. This work was also calculated dielectric function "(!) of the BGO and BSO, and its refractive index n(!) and re ectivity R(!). The best agreement with experimental data was again achieved by using mBJ P-semiconductor functional. The analysis "(!) enabled interpretation of optical absorption spectrum of BGO and BSO in terms of electronic transitions between bands. The results showed that the greater ow of energy transfer occurs 2p states to the states of Bi 6p, which consists of the steps of the scintillation process in BGO and BSO. Was concluded that experimental optical spectra of BGO and BSO exhibit strong temperature dependency, and that theoretical results presented in this dissertation describe con dently electronic and optical properties when measured at low temperatures. |
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Sousa, Osmar Machado deLalic, Milanhttp://lattes.cnpq.br/17053839025330942017-09-26T18:27:40Z2017-09-26T18:27:40Z2016-02-16Sousa, Osmar Machado de. Estudo teórico das propriedades estruturais, eletrônicas e ópticas dos compostos Bi4Ge3O12 e Bi4Si3O12. 2016. 77 f. Dissertação (Pós-Graduação em Física) - Universidade Federal de Sergipe, São Cristóvão, 2016.https://ri.ufs.br/handle/riufs/5361This dissertation presents a theoretical study, based on density functional theory (DFT), upon structural, electronic and optical properties of Bi4Ge3O12 (Bismuth germanate, BGO) and Bi4Si3O12 (Bismuth silicate, BSO) compounds. As a computational tool it was utilized Full Potential Linear Augmented Plane Wave Method (FPLAPW), implemented into WIEN2k computer code and considered as one of the most precise tools for electronic structure calculations of solid materials. Exchange and correlation e ects were simulated by LDA, GGA-PBEsol, BJ, mBJ-original, mBJ P-present and mBJ P-semiconductor functionals. Lattice parameters and all atomic positions within the BGO and BSO unit cells were computationally optimized in order to reach minimum energy con guration. The resulting structural parameters showed good agreement with experimental data. The results of electronic structure calculations (band structure and density of electron states DOS) were best tted to experiment while using the mBJ P-semiconductor functional. They revealed a nature and size of the compound's fundamental band gaps, as well as predominant orbital character of bands around it. According to the results, the BGO and BSO have indirect fundamental gaps of 5.05 and 5.36 eV in excellent concordance with the experimental value 5.0 eV (BGO) and 5.4 eV (BSO). For both compounds the valence band top is dominated by the O 2p-states, with non-negligible amount of the Bi 6s-states, while the conduction band bottom is consisted mostly of the Bi 6p-states. This work was also calculated dielectric function "(!) of the BGO and BSO, and its refractive index n(!) and re ectivity R(!). The best agreement with experimental data was again achieved by using mBJ P-semiconductor functional. The analysis "(!) enabled interpretation of optical absorption spectrum of BGO and BSO in terms of electronic transitions between bands. The results showed that the greater ow of energy transfer occurs 2p states to the states of Bi 6p, which consists of the steps of the scintillation process in BGO and BSO. Was concluded that experimental optical spectra of BGO and BSO exhibit strong temperature dependency, and that theoretical results presented in this dissertation describe con dently electronic and optical properties when measured at low temperatures.Esta disserta c~ao apresenta um estudo te orico baseado no formalismo da Teoria do Funcional da Densidade (DFT) sobre as propriedades estruturais, eletr^onicas e opticas dos compostos: Bi4Ge3O12 (Germanato de Bismuto, BGO) e Bi4Si3O12 (Silicato de Bismuto, BSO). Foi utilizado como m etodo de c alculo o \Full Potential Linear Augmented Plane Waves"(FPLAPW), implementado no c odigo WIEN2k, considerado um dos mais precisos m etodos para os c alculos de estruturas eletr^onicas dos s olidos cristalinos. Os efeitos de troca e correla c~ao eletr^onica foram simulados atrav es dos potenciais LDA, GGA-PBEsol, BJ, mBJ original, mBJ P-presente e mBJ P-semicondutores. Os par^ametros de rede e as posi c~oes at^omicas nas c elulas unit arias do BGO e BSO foram otimizadas, a m de atingir uma con gura c~ao de m nima energia possiv el. Os resultados obtidos para os par^ametros de rede e das posi c~oes at^omicas, de ambos os compostos, mostraram boa concord^ancia quando comparados com medidas experimentais. Os c alculos da estrutura eletr^onica (estrutura de bandas e densidade de estados eletr^onicos, DOS) exibiram melhor concord^ancia com a experi^encia quando o potencial mBJ P-semicondutor foi utilizado. Eles revelaram a natureza e o tamanho dos gaps fundamentais dos compostos, bem como o car ater orbital predominante por volta destes. De acordo com os resultados, o BGO e BSO possuem gaps fundamentais indiretos de 5.05 e 5.36 eV em excelente concord^ancia com os valores experimentais 5.0 eV (BGO) e 5.4 eV (BSO). O topo da banda de val^encia em ambos os compostos e dominada por estados 2p do O, com uma parcela n~ao desprez vel dos estados 6s do Bi, j a o fundo da banda de condu c~ao e formada por estados 6p do Bi. Neste trabalho tamb em foi calculada a fun c~ao diel etrica "(!) do BGO e BSO, bem como os seus ndices de refra c~ao n(!) e re etividade R(!). A melhor concord^ancia com os dados experimentais foi novamente atingida utilizando o funcional mBJ P-semicondutor. A an alise da "(!) possibilitou a interpreta c~ao do espectro de absor c~ao optica do BGO e BSO em termos das transi c~oes eletr^onicas entre as bandas. Os resultados revelaram que o uxo maior de tranfer^ encia de el etrons ocorre dos estados 2p de O para os estados 6p do Bi, o qual consiste uma das etapas do processo de cintila c~ao no BGO e BSO. Foi conclu do que os espectros opticos determinados experimentalmente exibem forte depend^encia com a temperatura, e que os resultados te oricos obtidos nessa disserta c~ao descrevem bem as propriedades opticas e eletr^onicas do BGO e BSO quando medidos em baixas temperaturas.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPESapplication/pdfporUniversidade Federal de SergipePós-Graduação em FísicaUFSBrasilFísicaPropriedades eletrônicasPropriedades ópticasDensidade funcionalCristaisTeoria funcional da densidadePhysicsElectronic structureOptical propertiesDensity functional theoryCIENCIAS EXATAS E DA TERRA::FISICAEstudo teórico das propriedades estruturais, eletrônicas e ópticas dos compostos Bi4Ge3O12 e Bi4Si3O12info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/masterThesisinfo:eu-repo/semantics/openAccessreponame:Repositório Institucional da UFSinstname:Universidade Federal de Sergipe (UFS)instacron:UFSORIGINALOSMAR_MACHADO_SOUSA.pdfapplication/pdf7216659https://ri.ufs.br/jspui/bitstream/riufs/5361/1/OSMAR_MACHADO_SOUSA.pdfeeb75384c805e843cc16e8c533cf6df1MD51TEXTOSMAR_MACHADO_SOUSA.pdf.txtOSMAR_MACHADO_SOUSA.pdf.txtExtracted texttext/plain127812https://ri.ufs.br/jspui/bitstream/riufs/5361/2/OSMAR_MACHADO_SOUSA.pdf.txt50612d97fdf5027087c39f4a49b5f92fMD52THUMBNAILOSMAR_MACHADO_SOUSA.pdf.jpgOSMAR_MACHADO_SOUSA.pdf.jpgGenerated Thumbnailimage/jpeg1227https://ri.ufs.br/jspui/bitstream/riufs/5361/3/OSMAR_MACHADO_SOUSA.pdf.jpg64aacaa4643f27b800085281193481bdMD53riufs/53612017-11-29 20:17:59.361oai:ufs.br:riufs/5361Repositório InstitucionalPUBhttps://ri.ufs.br/oai/requestrepositorio@academico.ufs.bropendoar:2017-11-29T23:17:59Repositório Institucional da UFS - Universidade Federal de Sergipe (UFS)false |
dc.title.por.fl_str_mv |
Estudo teórico das propriedades estruturais, eletrônicas e ópticas dos compostos Bi4Ge3O12 e Bi4Si3O12 |
title |
Estudo teórico das propriedades estruturais, eletrônicas e ópticas dos compostos Bi4Ge3O12 e Bi4Si3O12 |
spellingShingle |
Estudo teórico das propriedades estruturais, eletrônicas e ópticas dos compostos Bi4Ge3O12 e Bi4Si3O12 Sousa, Osmar Machado de Física Propriedades eletrônicas Propriedades ópticas Densidade funcional Cristais Teoria funcional da densidade Physics Electronic structure Optical properties Density functional theory CIENCIAS EXATAS E DA TERRA::FISICA |
title_short |
Estudo teórico das propriedades estruturais, eletrônicas e ópticas dos compostos Bi4Ge3O12 e Bi4Si3O12 |
title_full |
Estudo teórico das propriedades estruturais, eletrônicas e ópticas dos compostos Bi4Ge3O12 e Bi4Si3O12 |
title_fullStr |
Estudo teórico das propriedades estruturais, eletrônicas e ópticas dos compostos Bi4Ge3O12 e Bi4Si3O12 |
title_full_unstemmed |
Estudo teórico das propriedades estruturais, eletrônicas e ópticas dos compostos Bi4Ge3O12 e Bi4Si3O12 |
title_sort |
Estudo teórico das propriedades estruturais, eletrônicas e ópticas dos compostos Bi4Ge3O12 e Bi4Si3O12 |
author |
Sousa, Osmar Machado de |
author_facet |
Sousa, Osmar Machado de |
author_role |
author |
dc.contributor.author.fl_str_mv |
Sousa, Osmar Machado de |
dc.contributor.advisor1.fl_str_mv |
Lalic, Milan |
dc.contributor.authorLattes.fl_str_mv |
http://lattes.cnpq.br/1705383902533094 |
contributor_str_mv |
Lalic, Milan |
dc.subject.por.fl_str_mv |
Física Propriedades eletrônicas Propriedades ópticas Densidade funcional Cristais Teoria funcional da densidade |
topic |
Física Propriedades eletrônicas Propriedades ópticas Densidade funcional Cristais Teoria funcional da densidade Physics Electronic structure Optical properties Density functional theory CIENCIAS EXATAS E DA TERRA::FISICA |
dc.subject.eng.fl_str_mv |
Physics Electronic structure Optical properties Density functional theory |
dc.subject.cnpq.fl_str_mv |
CIENCIAS EXATAS E DA TERRA::FISICA |
description |
This dissertation presents a theoretical study, based on density functional theory (DFT), upon structural, electronic and optical properties of Bi4Ge3O12 (Bismuth germanate, BGO) and Bi4Si3O12 (Bismuth silicate, BSO) compounds. As a computational tool it was utilized Full Potential Linear Augmented Plane Wave Method (FPLAPW), implemented into WIEN2k computer code and considered as one of the most precise tools for electronic structure calculations of solid materials. Exchange and correlation e ects were simulated by LDA, GGA-PBEsol, BJ, mBJ-original, mBJ P-present and mBJ P-semiconductor functionals. Lattice parameters and all atomic positions within the BGO and BSO unit cells were computationally optimized in order to reach minimum energy con guration. The resulting structural parameters showed good agreement with experimental data. The results of electronic structure calculations (band structure and density of electron states DOS) were best tted to experiment while using the mBJ P-semiconductor functional. They revealed a nature and size of the compound's fundamental band gaps, as well as predominant orbital character of bands around it. According to the results, the BGO and BSO have indirect fundamental gaps of 5.05 and 5.36 eV in excellent concordance with the experimental value 5.0 eV (BGO) and 5.4 eV (BSO). For both compounds the valence band top is dominated by the O 2p-states, with non-negligible amount of the Bi 6s-states, while the conduction band bottom is consisted mostly of the Bi 6p-states. This work was also calculated dielectric function "(!) of the BGO and BSO, and its refractive index n(!) and re ectivity R(!). The best agreement with experimental data was again achieved by using mBJ P-semiconductor functional. The analysis "(!) enabled interpretation of optical absorption spectrum of BGO and BSO in terms of electronic transitions between bands. The results showed that the greater ow of energy transfer occurs 2p states to the states of Bi 6p, which consists of the steps of the scintillation process in BGO and BSO. Was concluded that experimental optical spectra of BGO and BSO exhibit strong temperature dependency, and that theoretical results presented in this dissertation describe con dently electronic and optical properties when measured at low temperatures. |
publishDate |
2016 |
dc.date.issued.fl_str_mv |
2016-02-16 |
dc.date.accessioned.fl_str_mv |
2017-09-26T18:27:40Z |
dc.date.available.fl_str_mv |
2017-09-26T18:27:40Z |
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.citation.fl_str_mv |
Sousa, Osmar Machado de. Estudo teórico das propriedades estruturais, eletrônicas e ópticas dos compostos Bi4Ge3O12 e Bi4Si3O12. 2016. 77 f. Dissertação (Pós-Graduação em Física) - Universidade Federal de Sergipe, São Cristóvão, 2016. |
dc.identifier.uri.fl_str_mv |
https://ri.ufs.br/handle/riufs/5361 |
identifier_str_mv |
Sousa, Osmar Machado de. Estudo teórico das propriedades estruturais, eletrônicas e ópticas dos compostos Bi4Ge3O12 e Bi4Si3O12. 2016. 77 f. Dissertação (Pós-Graduação em Física) - Universidade Federal de Sergipe, São Cristóvão, 2016. |
url |
https://ri.ufs.br/handle/riufs/5361 |
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Universidade Federal de Sergipe |
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UFS |
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Brasil |
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Universidade Federal de Sergipe |
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