Estudo de fases cristalinas no sistema Bi2O3-Tb4O7
Autor(a) principal: | |
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Data de Publicação: | 2009 |
Tipo de documento: | Dissertação |
Idioma: | por |
Título da fonte: | Repositório Institucional da UFG |
Texto Completo: | http://repositorio.bc.ufg.br/tede/handle/tde/821 |
Resumo: | A systematic study concerning the crystalline phases in the Bi2O3-rich region of the system Bi2O3-Tb4O7 was made. X-ray powder diffraction method, differential thermal analysis (DTA) and differential scanning calorimetry (DSC) were used in the study of the obtained crystalline phases. Sixteen samples with composition in the range of 4.21 to 33.33 mol% of Tb4O7 were synthesized at 800oC by solid state reaction synthesis. Three distinct crystalline phases were initially identified: a tetragonal phase in the composition range of 4.21 to 5.69 mol% of Tb4O7, a cubic phase for compositions between 6.12 and 29.03 mol% of Tb4O7, and a monoclinic one with 33.33 mol% of Tb4O7. The thermal stability of these compositions was rigorously investigated and the results shown that they are metastable phases in almost all studied range. Under thermal annealing at 500oC, tetragonal phase undergoes decomposition into two phases, monoclinic and rhombohedral ones. The cubic phase, under the same thermal annealing, decomposes partially into a rhombohedral one, except for the interval between 25.0 and 29.1 mol% of Tb4O7. In this case, there was not decomposition under thermal annealing at 500oC during 373 hours, suggesting the cubic phase is stable in this composition range. The monoclinic phase was also tested concerning its thermal stability, but no phase transition was verified. The existence of a possible composition range in the system Bi2O3-Tb4O7 with stable cubic -Bi2O3 type structure is a new and promise result, because of the high ionic conductivity presented by this phase |
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CARVALHO, Jesiel Freitashttp://lattes.cnpq.br/5841291496427516http://lattes.cnpq.br/6800985000083786MATOS, Lucyene Nascimento2014-07-29T15:07:11Z2010-04-072009-08-25MATOS, Lucyene Nascimento. Study of crystalline phases in the system Bi2O3-Tb4O7. 2009. 62 f. Dissertação (Mestrado em Ciências Exatas e da Terra) - Universidade Federal de Goiás, Goiânia, 2009.http://repositorio.bc.ufg.br/tede/handle/tde/821A systematic study concerning the crystalline phases in the Bi2O3-rich region of the system Bi2O3-Tb4O7 was made. X-ray powder diffraction method, differential thermal analysis (DTA) and differential scanning calorimetry (DSC) were used in the study of the obtained crystalline phases. Sixteen samples with composition in the range of 4.21 to 33.33 mol% of Tb4O7 were synthesized at 800oC by solid state reaction synthesis. Three distinct crystalline phases were initially identified: a tetragonal phase in the composition range of 4.21 to 5.69 mol% of Tb4O7, a cubic phase for compositions between 6.12 and 29.03 mol% of Tb4O7, and a monoclinic one with 33.33 mol% of Tb4O7. The thermal stability of these compositions was rigorously investigated and the results shown that they are metastable phases in almost all studied range. Under thermal annealing at 500oC, tetragonal phase undergoes decomposition into two phases, monoclinic and rhombohedral ones. The cubic phase, under the same thermal annealing, decomposes partially into a rhombohedral one, except for the interval between 25.0 and 29.1 mol% of Tb4O7. In this case, there was not decomposition under thermal annealing at 500oC during 373 hours, suggesting the cubic phase is stable in this composition range. The monoclinic phase was also tested concerning its thermal stability, but no phase transition was verified. The existence of a possible composition range in the system Bi2O3-Tb4O7 with stable cubic -Bi2O3 type structure is a new and promise result, because of the high ionic conductivity presented by this phaseUm estudo sistemático das fases cristalinas na região mais rica em óxido de bismuto no sistema Bi2O3-Tb4O7 foi realizado. As técnicas de Difração de Raios X pelo método do pó, Análise Térmica Diferencial (DTA) e Calorimetria Diferencial de Varredura (DSC) foram utilizadas no estudo das fases cristalinas obtidas. Dezesseis amostras com composição entre 4,21 e 33,33 mol% de Tb4O7 foram preparadas através de síntese por reação no estado sólido a 800oC. Três fases cristalinas distintas foram inicialmente identificadas: uma tetragonal, presente nas composições entre 4,21 e 5,69 mol% de Tb4O7, uma cúbica, para as composições entre 6,12 e 29,03 mol% de Tb4O7 e uma monoclínica com composição de 33,33 mol% de Tb4O7. Essas composições foram rigorosamente testadas quanto à sua estabilidade térmicas e os resultados indicaram que elas são metaestáveis em quase todo o intervalo investigado. Sob tratamento térmico a 500oC, a fase tetragonal se decompôs em duas fases, uma romboédrica e outra monoclínica. A fase cúbica, sob o mesmo tratamento térmico, se decompôs parcialmente em uma fase romboédrica, exceto para o intervalo compreendido entre 25,0 e 29,1 mol% de Tb4O7. Neste caso não houve decomposição sob tratamento térmico a 500oC durante 373 horas, indicando que a fase cúbica é estável neste intervalo de composição. A fase monoclínica também foi testada quanto à sua estabilidade, não tendo sido verificada nenhuma transição estrutural. A existência de uma possível faixa de composição no sistema Bi2O3-Tb4O7 com estrutura cúbica do tipo -Bi2O3 estável é um resultado inédito e promissor devido ela apresentar elevada condutividade iônicaMade available in DSpace on 2014-07-29T15:07:11Z (GMT). No. of bitstreams: 1 Dissertacao Lucyene Quimica.pdf: 715050 bytes, checksum: f0341d52acc4a9b488b447ca69a136f7 (MD5) Previous issue date: 2009-08-25application/pdfhttp://repositorio.bc.ufg.br/TEDE/retrieve/3587/Dissertacao%20Lucyene%20Quimica.pdf.jpgporUniversidade Federal de GoiásMestrado em FísicaUFGBRCiências Exatas e da Terrafases cristalinasóxidos - bismuto e térbioestabilidade de fasescrystalline phasesoxides - bismuth and terbiumphase stabilityCNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICAEstudo de fases cristalinas no sistema Bi2O3-Tb4O7Study of crystalline phases in the system Bi2O3-Tb4O7info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/masterThesisinfo:eu-repo/semantics/openAccessreponame:Repositório Institucional da UFGinstname:Universidade Federal de Goiás (UFG)instacron:UFGORIGINALDissertacao Lucyene Quimica.pdfapplication/pdf715050http://repositorio.bc.ufg.br/tede/bitstreams/a98efb17-3661-4d0a-a3f9-c3a9d11a30a9/downloadf0341d52acc4a9b488b447ca69a136f7MD51THUMBNAILDissertacao Lucyene Quimica.pdf.jpgDissertacao Lucyene Quimica.pdf.jpgGenerated Thumbnailimage/jpeg3395http://repositorio.bc.ufg.br/tede/bitstreams/c4f82245-c015-401e-934c-28643a60a4f8/download729df0f2586530741efabc68da1469c1MD52tde/8212014-07-30 03:06:43.57open.accessoai:repositorio.bc.ufg.br:tde/821http://repositorio.bc.ufg.br/tedeRepositório InstitucionalPUBhttp://repositorio.bc.ufg.br/oai/requesttasesdissertacoes.bc@ufg.bropendoar:2014-07-30T06:06:43Repositório Institucional da UFG - Universidade Federal de Goiás (UFG)false |
dc.title.por.fl_str_mv |
Estudo de fases cristalinas no sistema Bi2O3-Tb4O7 |
dc.title.alternative.eng.fl_str_mv |
Study of crystalline phases in the system Bi2O3-Tb4O7 |
title |
Estudo de fases cristalinas no sistema Bi2O3-Tb4O7 |
spellingShingle |
Estudo de fases cristalinas no sistema Bi2O3-Tb4O7 MATOS, Lucyene Nascimento fases cristalinas óxidos - bismuto e térbio estabilidade de fases crystalline phases oxides - bismuth and terbium phase stability CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA |
title_short |
Estudo de fases cristalinas no sistema Bi2O3-Tb4O7 |
title_full |
Estudo de fases cristalinas no sistema Bi2O3-Tb4O7 |
title_fullStr |
Estudo de fases cristalinas no sistema Bi2O3-Tb4O7 |
title_full_unstemmed |
Estudo de fases cristalinas no sistema Bi2O3-Tb4O7 |
title_sort |
Estudo de fases cristalinas no sistema Bi2O3-Tb4O7 |
author |
MATOS, Lucyene Nascimento |
author_facet |
MATOS, Lucyene Nascimento |
author_role |
author |
dc.contributor.advisor1.fl_str_mv |
CARVALHO, Jesiel Freitas |
dc.contributor.advisor1Lattes.fl_str_mv |
http://lattes.cnpq.br/5841291496427516 |
dc.contributor.authorLattes.fl_str_mv |
http://lattes.cnpq.br/6800985000083786 |
dc.contributor.author.fl_str_mv |
MATOS, Lucyene Nascimento |
contributor_str_mv |
CARVALHO, Jesiel Freitas |
dc.subject.por.fl_str_mv |
fases cristalinas óxidos - bismuto e térbio estabilidade de fases |
topic |
fases cristalinas óxidos - bismuto e térbio estabilidade de fases crystalline phases oxides - bismuth and terbium phase stability CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA |
dc.subject.eng.fl_str_mv |
crystalline phases oxides - bismuth and terbium phase stability |
dc.subject.cnpq.fl_str_mv |
CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA |
description |
A systematic study concerning the crystalline phases in the Bi2O3-rich region of the system Bi2O3-Tb4O7 was made. X-ray powder diffraction method, differential thermal analysis (DTA) and differential scanning calorimetry (DSC) were used in the study of the obtained crystalline phases. Sixteen samples with composition in the range of 4.21 to 33.33 mol% of Tb4O7 were synthesized at 800oC by solid state reaction synthesis. Three distinct crystalline phases were initially identified: a tetragonal phase in the composition range of 4.21 to 5.69 mol% of Tb4O7, a cubic phase for compositions between 6.12 and 29.03 mol% of Tb4O7, and a monoclinic one with 33.33 mol% of Tb4O7. The thermal stability of these compositions was rigorously investigated and the results shown that they are metastable phases in almost all studied range. Under thermal annealing at 500oC, tetragonal phase undergoes decomposition into two phases, monoclinic and rhombohedral ones. The cubic phase, under the same thermal annealing, decomposes partially into a rhombohedral one, except for the interval between 25.0 and 29.1 mol% of Tb4O7. In this case, there was not decomposition under thermal annealing at 500oC during 373 hours, suggesting the cubic phase is stable in this composition range. The monoclinic phase was also tested concerning its thermal stability, but no phase transition was verified. The existence of a possible composition range in the system Bi2O3-Tb4O7 with stable cubic -Bi2O3 type structure is a new and promise result, because of the high ionic conductivity presented by this phase |
publishDate |
2009 |
dc.date.issued.fl_str_mv |
2009-08-25 |
dc.date.available.fl_str_mv |
2010-04-07 |
dc.date.accessioned.fl_str_mv |
2014-07-29T15:07:11Z |
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 |
MATOS, Lucyene Nascimento. Study of crystalline phases in the system Bi2O3-Tb4O7. 2009. 62 f. Dissertação (Mestrado em Ciências Exatas e da Terra) - Universidade Federal de Goiás, Goiânia, 2009. |
dc.identifier.uri.fl_str_mv |
http://repositorio.bc.ufg.br/tede/handle/tde/821 |
identifier_str_mv |
MATOS, Lucyene Nascimento. Study of crystalline phases in the system Bi2O3-Tb4O7. 2009. 62 f. Dissertação (Mestrado em Ciências Exatas e da Terra) - Universidade Federal de Goiás, Goiânia, 2009. |
url |
http://repositorio.bc.ufg.br/tede/handle/tde/821 |
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por |
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Universidade Federal de Goiás |
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Mestrado em Física |
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UFG |
dc.publisher.country.fl_str_mv |
BR |
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Ciências Exatas e da Terra |
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Universidade Federal de Goiás |
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