Obtenção, propriedades e fenomenologia de materiais ferroelétricos com estrutura tungstênio bronze
Autor(a) principal: | |
---|---|
Data de Publicação: | 2007 |
Tipo de documento: | Tese |
Idioma: | por |
Título da fonte: | Repositório Institucional da UFSCAR |
Texto Completo: | https://repositorio.ufscar.br/handle/ufscar/4897 |
Resumo: | The processing of lead metaniobate (PN) ferroelectric ceramics was optimized, therefore, in this work, the main details to obtain PN ceramics with density higher than 96 % of the ideal density are presented and discussed. Taking into account the potential of the lead metaniobate for different applications, mainly for high temperatures, the phase transition characteristics of this material, in both undoped and doped compositions, were detaily investigated. It was verified that the addition of Ti4+ enhances the densification and increase the Curie temperature. Nevertheless, the ferro-paraelectric phase transition is affected by an electric conductive process, which appears in temperatures below and above the Curie temperature. The double ionized oxygen vacancies are proposed to be the charge carriers responsible for this conductive process. The undoped and Ti4+-doped PN ceramics show low values of the mechanical quality factor and high piezoelectric anisotropy, which are desired characteristics for the fabrication of broad band electro-mechanical transducers, mainly to operate in the thickness mode. The addition of Ba2+ to the PN (PBN) considerably decreases the Curie temperature, but it induces a phase transition, leading to the formation of a morphotropic phase boundary (MPB) around the composition with 37 % of Ba2+, in which some properties are enhanced. In this way, the characteristics of the ferro-paraelectric phase transition, for compositions around the MPB, were investigated for Ba2+-doped PN ceramics, textured by hot forging. It was found that the MPB extends towards a wide composition range, in which both tetragonal 4mm and orthorhombic m2m tungsten bronze (TB) phases coexist. In addition, with the increasing temperature, two phase transitions were observed for this composition range. First, the material portion with orthorhombic (m2m) symmetry transforms into the tetragonal (4mm) phase and, second, the 4mm phase (that represents the material in its totality) transforms into the paraelectric phase with the tetragonal 4/mmm TB symmetry. These results helped to complete the reported PBN phase diagram. Moreover, it was found that the La3+ addition to the PBN, for the composition with 56 % of Pb2+, induces the formation of the orthorhombic (m2m) phase. All the (doped and undoped) PN ceramics showed two dielectric dispersion processes at low temperatures, i.e. from 30 to 300 K, which seems to be an inherent feature of all materials with TB structure and ((A1)x(A2)5-xNb10O30) structural formula. The two processes were associated to a phase transition and the formation of incommensurate structures, respectively. The influence of such incommensurate structures on the relaxor behavior and diffusivity of the ferro-paraelectric phase transition was also analyzed. |
id |
SCAR_4f7b20e5f1014982506ef8f54f83d0c5 |
---|---|
oai_identifier_str |
oai:repositorio.ufscar.br:ufscar/4897 |
network_acronym_str |
SCAR |
network_name_str |
Repositório Institucional da UFSCAR |
repository_id_str |
4322 |
spelling |
Zambrano, Michel VenetGarcia, Ducineihttp://lattes.cnpq.br/5236758856687873http://lattes.cnpq.br/18303762292860388eed7b90-1d1a-4432-93c7-157b243d93e02016-06-02T20:15:16Z2007-11-132016-06-02T20:15:16Z2007-02-23ZAMBRANO, Michel Venet. Obtenção, propriedades e fenomenologia de materiais ferroelétricos com estrutura tungstênio bronze.. 2007. 147 f. Tese (Doutorado em Ciências Exatas e da Terra) - Universidade Federal de São Carlos, São Carlos, 2007.https://repositorio.ufscar.br/handle/ufscar/4897The processing of lead metaniobate (PN) ferroelectric ceramics was optimized, therefore, in this work, the main details to obtain PN ceramics with density higher than 96 % of the ideal density are presented and discussed. Taking into account the potential of the lead metaniobate for different applications, mainly for high temperatures, the phase transition characteristics of this material, in both undoped and doped compositions, were detaily investigated. It was verified that the addition of Ti4+ enhances the densification and increase the Curie temperature. Nevertheless, the ferro-paraelectric phase transition is affected by an electric conductive process, which appears in temperatures below and above the Curie temperature. The double ionized oxygen vacancies are proposed to be the charge carriers responsible for this conductive process. The undoped and Ti4+-doped PN ceramics show low values of the mechanical quality factor and high piezoelectric anisotropy, which are desired characteristics for the fabrication of broad band electro-mechanical transducers, mainly to operate in the thickness mode. The addition of Ba2+ to the PN (PBN) considerably decreases the Curie temperature, but it induces a phase transition, leading to the formation of a morphotropic phase boundary (MPB) around the composition with 37 % of Ba2+, in which some properties are enhanced. In this way, the characteristics of the ferro-paraelectric phase transition, for compositions around the MPB, were investigated for Ba2+-doped PN ceramics, textured by hot forging. It was found that the MPB extends towards a wide composition range, in which both tetragonal 4mm and orthorhombic m2m tungsten bronze (TB) phases coexist. In addition, with the increasing temperature, two phase transitions were observed for this composition range. First, the material portion with orthorhombic (m2m) symmetry transforms into the tetragonal (4mm) phase and, second, the 4mm phase (that represents the material in its totality) transforms into the paraelectric phase with the tetragonal 4/mmm TB symmetry. These results helped to complete the reported PBN phase diagram. Moreover, it was found that the La3+ addition to the PBN, for the composition with 56 % of Pb2+, induces the formation of the orthorhombic (m2m) phase. All the (doped and undoped) PN ceramics showed two dielectric dispersion processes at low temperatures, i.e. from 30 to 300 K, which seems to be an inherent feature of all materials with TB structure and ((A1)x(A2)5-xNb10O30) structural formula. The two processes were associated to a phase transition and the formation of incommensurate structures, respectively. The influence of such incommensurate structures on the relaxor behavior and diffusivity of the ferro-paraelectric phase transition was also analyzed.O processo de obtenção de cerâmicas ferroelétricas de metaniobato de chumbo (PN) foi otimizado, de forma que este trabalho oferece os detalhes necessários para a obtenção de cerâmicas de PN com densidades superiores aos 96 % da densidade ideal. Levando-se em consideração a potencialidade do metaniobato de chumbo para diferentes tipos de aplicações, principalmente em altas temperaturas, foi realizada uma investigação detalhada das características da transição de fase nesse material puro e dopado. Verificou-se que a adição de Ti4+ favorece a densificação das cerâmicas e aumenta a temperatura de Curie. Contudo, a transição de fase ferro-paraelétrica é afetada por um processo de condutividade elétrica que se manifesta tanto em temperaturas inferiores quanto superiores à temperatura de Curie. Por outro lado, determinou-se que o portador de carga responsável por tal processo condutivo são as vacâncias de oxigênio duplamente ionizadas. As cerâmicas de PN, puras e dopadas com Ti4+, apresentaram baixos valores do fator de qualidade mecânico e uma alta anisotropia piezoelétrica. Tais características são desejáveis para a fabricação de transdutores eletro-mecânicos de banda larga, principalmente para operar no modo de espessura. A adição de Ba2+ ao PN (PBN) diminui consideravelmente a sua temperatura de Curie, mas induz uma transição de fase, formando um contorno de fase morfotrópico (CFM), ao redor da composição com 37 % de Ba2+, na qual algumas propriedades são maximizadas. Assim, utilizando cerâmicas texturadas de PN dopadas com Ba2+, obtidas por forjamento a quente, foi possível investigar as características da transição de fase ferro-paraelétrica para composições ao redor do CFM. Verificou-se que a região do CFM se estende em uma ampla faixa de composições onde coexistem as estruturas tungstênio bronze (TB) com simetria tetragonal 4mm e ortorrômbica m2m. Observou-se também que, nessa região de composições, ocorrem duas transições de fase com o aumento da temperatura. Inicialmente a fração de fase ortorrômbica se transforma em tetragonal e, posteriormente, todo o material com simetria 4mm passa ao estado paraelétrico, onde adota a estrutura TB com simetria tetragonal 4/mmm. Com esses resultados foi possível complementar o diagrama de fases do PBN existente na literatura. A adição de La3+, na cerâmica de PBN com 56 % de chumbo, favoreceu a formação da estrutura TB com simetria ortorrômbica. Em todas as cerâmicas de PN (puro e dopado), foram observados dois processos de dispersão dielétrica em baixas temperaturas, entre 30 e 300 K, aparentemente são inerentes a todos os materiais com estrutura TB e fórmula estrutural ((A1)x(A2)5-xNb10O30), e estão relacionados com uma transição de fase e com a formação de superestruturas incomensuráveis respectivamente. Foi analisada também a influência de tais superestruturas no comportamento relaxor e na difusividade da transição de fase ferro-paraelétrica das cerâmicas estudadas.Universidade Federal de Sao Carlosapplication/pdfporUniversidade Federal de São CarlosPrograma de Pós-Graduação em Física - PPGFUFSCarBRFísica da matéria condensadaFerroelétricosTungstênio-bronzeNiobato de chumbo (PN)Propriedades dielétricasTransição de faseCIENCIAS EXATAS E DA TERRA::FISICAObtenção, propriedades e fenomenologia de materiais ferroelétricos com estrutura tungstênio bronzeinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/doctoralThesis-1-18c0977cd-d1ed-46a1-b1ad-912e2955cb17info:eu-repo/semantics/openAccessreponame:Repositório Institucional da UFSCARinstname:Universidade Federal de São Carlos (UFSCAR)instacron:UFSCARORIGINALTeseMVZ.pdfapplication/pdf4192238https://repositorio.ufscar.br/bitstream/ufscar/4897/1/TeseMVZ.pdfd559e495090cafdd0af882b5cd3cf421MD51THUMBNAILTeseMVZ.pdf.jpgTeseMVZ.pdf.jpgIM Thumbnailimage/jpeg9759https://repositorio.ufscar.br/bitstream/ufscar/4897/2/TeseMVZ.pdf.jpg2316545b8328bd383fa72cb961913042MD52ufscar/48972023-09-18 18:31:45.864oai:repositorio.ufscar.br:ufscar/4897Repositório InstitucionalPUBhttps://repositorio.ufscar.br/oai/requestopendoar:43222023-09-18T18:31:45Repositório Institucional da UFSCAR - Universidade Federal de São Carlos (UFSCAR)false |
dc.title.por.fl_str_mv |
Obtenção, propriedades e fenomenologia de materiais ferroelétricos com estrutura tungstênio bronze |
title |
Obtenção, propriedades e fenomenologia de materiais ferroelétricos com estrutura tungstênio bronze |
spellingShingle |
Obtenção, propriedades e fenomenologia de materiais ferroelétricos com estrutura tungstênio bronze Zambrano, Michel Venet Física da matéria condensada Ferroelétricos Tungstênio-bronze Niobato de chumbo (PN) Propriedades dielétricas Transição de fase CIENCIAS EXATAS E DA TERRA::FISICA |
title_short |
Obtenção, propriedades e fenomenologia de materiais ferroelétricos com estrutura tungstênio bronze |
title_full |
Obtenção, propriedades e fenomenologia de materiais ferroelétricos com estrutura tungstênio bronze |
title_fullStr |
Obtenção, propriedades e fenomenologia de materiais ferroelétricos com estrutura tungstênio bronze |
title_full_unstemmed |
Obtenção, propriedades e fenomenologia de materiais ferroelétricos com estrutura tungstênio bronze |
title_sort |
Obtenção, propriedades e fenomenologia de materiais ferroelétricos com estrutura tungstênio bronze |
author |
Zambrano, Michel Venet |
author_facet |
Zambrano, Michel Venet |
author_role |
author |
dc.contributor.authorlattes.por.fl_str_mv |
http://lattes.cnpq.br/1830376229286038 |
dc.contributor.author.fl_str_mv |
Zambrano, Michel Venet |
dc.contributor.advisor1.fl_str_mv |
Garcia, Ducinei |
dc.contributor.advisor1Lattes.fl_str_mv |
http://lattes.cnpq.br/5236758856687873 |
dc.contributor.authorID.fl_str_mv |
8eed7b90-1d1a-4432-93c7-157b243d93e0 |
contributor_str_mv |
Garcia, Ducinei |
dc.subject.por.fl_str_mv |
Física da matéria condensada Ferroelétricos Tungstênio-bronze Niobato de chumbo (PN) Propriedades dielétricas Transição de fase |
topic |
Física da matéria condensada Ferroelétricos Tungstênio-bronze Niobato de chumbo (PN) Propriedades dielétricas Transição de fase CIENCIAS EXATAS E DA TERRA::FISICA |
dc.subject.cnpq.fl_str_mv |
CIENCIAS EXATAS E DA TERRA::FISICA |
description |
The processing of lead metaniobate (PN) ferroelectric ceramics was optimized, therefore, in this work, the main details to obtain PN ceramics with density higher than 96 % of the ideal density are presented and discussed. Taking into account the potential of the lead metaniobate for different applications, mainly for high temperatures, the phase transition characteristics of this material, in both undoped and doped compositions, were detaily investigated. It was verified that the addition of Ti4+ enhances the densification and increase the Curie temperature. Nevertheless, the ferro-paraelectric phase transition is affected by an electric conductive process, which appears in temperatures below and above the Curie temperature. The double ionized oxygen vacancies are proposed to be the charge carriers responsible for this conductive process. The undoped and Ti4+-doped PN ceramics show low values of the mechanical quality factor and high piezoelectric anisotropy, which are desired characteristics for the fabrication of broad band electro-mechanical transducers, mainly to operate in the thickness mode. The addition of Ba2+ to the PN (PBN) considerably decreases the Curie temperature, but it induces a phase transition, leading to the formation of a morphotropic phase boundary (MPB) around the composition with 37 % of Ba2+, in which some properties are enhanced. In this way, the characteristics of the ferro-paraelectric phase transition, for compositions around the MPB, were investigated for Ba2+-doped PN ceramics, textured by hot forging. It was found that the MPB extends towards a wide composition range, in which both tetragonal 4mm and orthorhombic m2m tungsten bronze (TB) phases coexist. In addition, with the increasing temperature, two phase transitions were observed for this composition range. First, the material portion with orthorhombic (m2m) symmetry transforms into the tetragonal (4mm) phase and, second, the 4mm phase (that represents the material in its totality) transforms into the paraelectric phase with the tetragonal 4/mmm TB symmetry. These results helped to complete the reported PBN phase diagram. Moreover, it was found that the La3+ addition to the PBN, for the composition with 56 % of Pb2+, induces the formation of the orthorhombic (m2m) phase. All the (doped and undoped) PN ceramics showed two dielectric dispersion processes at low temperatures, i.e. from 30 to 300 K, which seems to be an inherent feature of all materials with TB structure and ((A1)x(A2)5-xNb10O30) structural formula. The two processes were associated to a phase transition and the formation of incommensurate structures, respectively. The influence of such incommensurate structures on the relaxor behavior and diffusivity of the ferro-paraelectric phase transition was also analyzed. |
publishDate |
2007 |
dc.date.available.fl_str_mv |
2007-11-13 2016-06-02T20:15:16Z |
dc.date.issued.fl_str_mv |
2007-02-23 |
dc.date.accessioned.fl_str_mv |
2016-06-02T20:15:16Z |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/doctoralThesis |
format |
doctoralThesis |
status_str |
publishedVersion |
dc.identifier.citation.fl_str_mv |
ZAMBRANO, Michel Venet. Obtenção, propriedades e fenomenologia de materiais ferroelétricos com estrutura tungstênio bronze.. 2007. 147 f. Tese (Doutorado em Ciências Exatas e da Terra) - Universidade Federal de São Carlos, São Carlos, 2007. |
dc.identifier.uri.fl_str_mv |
https://repositorio.ufscar.br/handle/ufscar/4897 |
identifier_str_mv |
ZAMBRANO, Michel Venet. Obtenção, propriedades e fenomenologia de materiais ferroelétricos com estrutura tungstênio bronze.. 2007. 147 f. Tese (Doutorado em Ciências Exatas e da Terra) - Universidade Federal de São Carlos, São Carlos, 2007. |
url |
https://repositorio.ufscar.br/handle/ufscar/4897 |
dc.language.iso.fl_str_mv |
por |
language |
por |
dc.relation.confidence.fl_str_mv |
-1 -1 |
dc.relation.authority.fl_str_mv |
8c0977cd-d1ed-46a1-b1ad-912e2955cb17 |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
eu_rights_str_mv |
openAccess |
dc.format.none.fl_str_mv |
application/pdf |
dc.publisher.none.fl_str_mv |
Universidade Federal de São Carlos |
dc.publisher.program.fl_str_mv |
Programa de Pós-Graduação em Física - PPGF |
dc.publisher.initials.fl_str_mv |
UFSCar |
dc.publisher.country.fl_str_mv |
BR |
publisher.none.fl_str_mv |
Universidade Federal de São Carlos |
dc.source.none.fl_str_mv |
reponame:Repositório Institucional da UFSCAR instname:Universidade Federal de São Carlos (UFSCAR) instacron:UFSCAR |
instname_str |
Universidade Federal de São Carlos (UFSCAR) |
instacron_str |
UFSCAR |
institution |
UFSCAR |
reponame_str |
Repositório Institucional da UFSCAR |
collection |
Repositório Institucional da UFSCAR |
bitstream.url.fl_str_mv |
https://repositorio.ufscar.br/bitstream/ufscar/4897/1/TeseMVZ.pdf https://repositorio.ufscar.br/bitstream/ufscar/4897/2/TeseMVZ.pdf.jpg |
bitstream.checksum.fl_str_mv |
d559e495090cafdd0af882b5cd3cf421 2316545b8328bd383fa72cb961913042 |
bitstream.checksumAlgorithm.fl_str_mv |
MD5 MD5 |
repository.name.fl_str_mv |
Repositório Institucional da UFSCAR - Universidade Federal de São Carlos (UFSCAR) |
repository.mail.fl_str_mv |
|
_version_ |
1802136280245469184 |