High temperature emissivity, reflectivity, and x-ray absorption of BiFeO3
Autor(a) principal: | |
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Data de Publicação: | 2010 |
Outros Autores: | , , , , , , |
Tipo de documento: | Artigo |
Idioma: | eng |
Título da fonte: | Repositório Institucional da UFRGS |
Texto Completo: | http://hdl.handle.net/10183/96281 |
Resumo: | We report on the lattice evolution of BiFeO3 as function of temperature using far infrared emissivity, reflectivity, and x-ray absorption local structure. A power law fit to the lowest frequency soft phonon in the magnetic ordered phase yields an exponent β=0.25 as for a tricritical point. At about 200 K below TN~640 K it ceases softening as consequence of BiFeO3 metastability. We identified this temperature as corresponding to a crossover transition to an order-disorder regime. Above~700 K strong band overlapping, merging, and smearing of modes are consequence of thermal fluctuations and chemical disorder. Vibrational modes show band splits in the ferroelectric phase as emerging from triple degenerated species as from a paraelectric cubic phase above TC~1090 K. Temperature dependent x-ray absorption near edge structure XANES at the Fe K edge shows that lower temperature Fe3+ turns into Fe2+. While this matches the FeO wüstite XANES profile, the Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking of long-range coherence. We did not find an insulator to metal transition prior to melting. |
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Massa, Néstor E.Del Campo, LeireMeneses, Domingos de SouzaEchegut, PatrickFabbris, Gilberto Fernandes LopesAzevedo, Gustavo de MedeirosMartínez Lope, María JesúsAlonso, José Antônio2014-06-10T02:05:14Z20100021-8979http://hdl.handle.net/10183/96281000767131We report on the lattice evolution of BiFeO3 as function of temperature using far infrared emissivity, reflectivity, and x-ray absorption local structure. A power law fit to the lowest frequency soft phonon in the magnetic ordered phase yields an exponent β=0.25 as for a tricritical point. At about 200 K below TN~640 K it ceases softening as consequence of BiFeO3 metastability. We identified this temperature as corresponding to a crossover transition to an order-disorder regime. Above~700 K strong band overlapping, merging, and smearing of modes are consequence of thermal fluctuations and chemical disorder. Vibrational modes show band splits in the ferroelectric phase as emerging from triple degenerated species as from a paraelectric cubic phase above TC~1090 K. Temperature dependent x-ray absorption near edge structure XANES at the Fe K edge shows that lower temperature Fe3+ turns into Fe2+. While this matches the FeO wüstite XANES profile, the Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking of long-range coherence. We did not find an insulator to metal transition prior to melting.application/pdfengJournal of applied physics. Melville. Vol. 108, no. 8 (Oct. 2010), 084114, 8 p.Física da matéria condensadaCompostos de bismutoFlutuações críticasPontos criticosEmissividadeTransições ferroelétricasTransformações displacivasFononsReflexibilidadeXanesHigh temperature emissivity, reflectivity, and x-ray absorption of BiFeO3Estrangeiroinfo:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/openAccessreponame:Repositório Institucional da UFRGSinstname:Universidade Federal do Rio Grande do Sul (UFRGS)instacron:UFRGSORIGINAL000767131.pdf000767131.pdfTexto completo (inglês)application/pdf1670853http://www.lume.ufrgs.br/bitstream/10183/96281/1/000767131.pdf34757fd6130a91e124b46a675e204884MD51TEXT000767131.pdf.txt000767131.pdf.txtExtracted Texttext/plain43687http://www.lume.ufrgs.br/bitstream/10183/96281/2/000767131.pdf.txt09947e5953695e335871ada4f5581cacMD52THUMBNAIL000767131.pdf.jpg000767131.pdf.jpgGenerated Thumbnailimage/jpeg1589http://www.lume.ufrgs.br/bitstream/10183/96281/3/000767131.pdf.jpga3979a5191e3faae7ac77c4e52aaecb6MD5310183/962812018-10-18 08:03:51.158oai:www.lume.ufrgs.br:10183/96281Repositório de PublicaçõesPUBhttps://lume.ufrgs.br/oai/requestopendoar:2018-10-18T11:03:51Repositório Institucional da UFRGS - Universidade Federal do Rio Grande do Sul (UFRGS)false |
dc.title.pt_BR.fl_str_mv |
High temperature emissivity, reflectivity, and x-ray absorption of BiFeO3 |
title |
High temperature emissivity, reflectivity, and x-ray absorption of BiFeO3 |
spellingShingle |
High temperature emissivity, reflectivity, and x-ray absorption of BiFeO3 Massa, Néstor E. Física da matéria condensada Compostos de bismuto Flutuações críticas Pontos criticos Emissividade Transições ferroelétricas Transformações displacivas Fonons Reflexibilidade Xanes |
title_short |
High temperature emissivity, reflectivity, and x-ray absorption of BiFeO3 |
title_full |
High temperature emissivity, reflectivity, and x-ray absorption of BiFeO3 |
title_fullStr |
High temperature emissivity, reflectivity, and x-ray absorption of BiFeO3 |
title_full_unstemmed |
High temperature emissivity, reflectivity, and x-ray absorption of BiFeO3 |
title_sort |
High temperature emissivity, reflectivity, and x-ray absorption of BiFeO3 |
author |
Massa, Néstor E. |
author_facet |
Massa, Néstor E. Del Campo, Leire Meneses, Domingos de Souza Echegut, Patrick Fabbris, Gilberto Fernandes Lopes Azevedo, Gustavo de Medeiros Martínez Lope, María Jesús Alonso, José Antônio |
author_role |
author |
author2 |
Del Campo, Leire Meneses, Domingos de Souza Echegut, Patrick Fabbris, Gilberto Fernandes Lopes Azevedo, Gustavo de Medeiros Martínez Lope, María Jesús Alonso, José Antônio |
author2_role |
author author author author author author author |
dc.contributor.author.fl_str_mv |
Massa, Néstor E. Del Campo, Leire Meneses, Domingos de Souza Echegut, Patrick Fabbris, Gilberto Fernandes Lopes Azevedo, Gustavo de Medeiros Martínez Lope, María Jesús Alonso, José Antônio |
dc.subject.por.fl_str_mv |
Física da matéria condensada Compostos de bismuto Flutuações críticas Pontos criticos Emissividade Transições ferroelétricas Transformações displacivas Fonons Reflexibilidade Xanes |
topic |
Física da matéria condensada Compostos de bismuto Flutuações críticas Pontos criticos Emissividade Transições ferroelétricas Transformações displacivas Fonons Reflexibilidade Xanes |
description |
We report on the lattice evolution of BiFeO3 as function of temperature using far infrared emissivity, reflectivity, and x-ray absorption local structure. A power law fit to the lowest frequency soft phonon in the magnetic ordered phase yields an exponent β=0.25 as for a tricritical point. At about 200 K below TN~640 K it ceases softening as consequence of BiFeO3 metastability. We identified this temperature as corresponding to a crossover transition to an order-disorder regime. Above~700 K strong band overlapping, merging, and smearing of modes are consequence of thermal fluctuations and chemical disorder. Vibrational modes show band splits in the ferroelectric phase as emerging from triple degenerated species as from a paraelectric cubic phase above TC~1090 K. Temperature dependent x-ray absorption near edge structure XANES at the Fe K edge shows that lower temperature Fe3+ turns into Fe2+. While this matches the FeO wüstite XANES profile, the Bi LIII-edge downshift suggests a high temperature very complex bond configuration at the distorted A perovskite site. Overall, our local structural measurements reveal high temperature defect-induced irreversible lattice changes, below, and above the ferroelectric transition, in an environment lacking of long-range coherence. We did not find an insulator to metal transition prior to melting. |
publishDate |
2010 |
dc.date.issued.fl_str_mv |
2010 |
dc.date.accessioned.fl_str_mv |
2014-06-10T02:05:14Z |
dc.type.driver.fl_str_mv |
Estrangeiro info:eu-repo/semantics/article |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
format |
article |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
http://hdl.handle.net/10183/96281 |
dc.identifier.issn.pt_BR.fl_str_mv |
0021-8979 |
dc.identifier.nrb.pt_BR.fl_str_mv |
000767131 |
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0021-8979 000767131 |
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http://hdl.handle.net/10183/96281 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.relation.ispartof.pt_BR.fl_str_mv |
Journal of applied physics. Melville. Vol. 108, no. 8 (Oct. 2010), 084114, 8 p. |
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info:eu-repo/semantics/openAccess |
eu_rights_str_mv |
openAccess |
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