Ferromagnetismo diluído de semicondutores mistos CeO2-ZnO:M (M = Fe, Co, Ni)
Ano de defesa: | 2012 |
---|---|
Autor(a) principal: | |
Orientador(a): | |
Banca de defesa: | |
Tipo de documento: | Tese |
Tipo de acesso: | Acesso aberto |
Idioma: | por |
Instituição de defesa: |
Universidade Federal de Sergipe
|
Programa de Pós-Graduação: |
Pós-Graduação em Física
|
Departamento: |
Não Informado pela instituição
|
País: |
BR
|
Palavras-chave em Português: | |
Palavras-chave em Inglês: | |
Área do conhecimento CNPq: | |
Link de acesso: | https://ri.ufs.br/handle/riufs/5238 |
Resumo: | In this paper we study the structural and magnetic characterization of samples CeO2, CeO2-Zn and ZnO: M (Fe, Co, Ni) obtained via the proteic sol-gel process, where the organic precursor is coconut water. The solutions were prepared by dissolving cerium nitrate and nitrate zinc for samples doped with Zn and cerium nitrate, zinc and cobalt or iron in the samples doped with Fe or Co and were later brought the muffle where they remained for 24 h at 100 º C to form the xerogel. Then the samples were calcined at 400, 600, 800 and 1000 º C for one hour in air. After calcinations the powders were analyzed in the X-ray diffraction to identify the phases formed and to infer a limit of solubility for the systems studied. By measuring the Raman spectroscopy identified the presence of oxygen vacancies according to the literature to induce a ferromagnetic behavior, in addition to confirming the results obtained using XRD. The magnetic properties were also studied by SQUID magnetometer. In general, the samples studied here showed a ferromagnetic behavior at 2 K with very low values of Hc and Mr and had a saturation magnetization (Ms) increases with increasing concentration of dopant ions and calcinations temperature. It was observed a weak ferromagnetism at room temperature too. Our results indicate that the origin of ferromagnetism is associated with formation of oxygen vacancies. Samples of mixed matrix doped iron showed an interesting change in behavior. When the concentration of dopant ions was x ≤ 0.04 the samples were ferromagnetic when the concentration was x ≥ 0.05 it showed antiferromagnetic with Néel temperature approximately equal to 12, 27 and 13 K for Fe with x = 0.05, 0.075 and 0.1, respectively. |
id |
UFS-2_6a27d672ab64ceeee43d0b003d86b4c7 |
---|---|
oai_identifier_str |
oai:ufs.br:riufs/5238 |
network_acronym_str |
UFS-2 |
network_name_str |
Repositório Institucional da UFS |
repository_id_str |
|
spelling |
Santos, Tâmara Sibele doshttp://lattes.cnpq.br/3264248290660253Macêdo, Marcelo Andrade2017-09-26T18:23:44Z2017-09-26T18:23:44Z2012-02-24https://ri.ufs.br/handle/riufs/5238In this paper we study the structural and magnetic characterization of samples CeO2, CeO2-Zn and ZnO: M (Fe, Co, Ni) obtained via the proteic sol-gel process, where the organic precursor is coconut water. The solutions were prepared by dissolving cerium nitrate and nitrate zinc for samples doped with Zn and cerium nitrate, zinc and cobalt or iron in the samples doped with Fe or Co and were later brought the muffle where they remained for 24 h at 100 º C to form the xerogel. Then the samples were calcined at 400, 600, 800 and 1000 º C for one hour in air. After calcinations the powders were analyzed in the X-ray diffraction to identify the phases formed and to infer a limit of solubility for the systems studied. By measuring the Raman spectroscopy identified the presence of oxygen vacancies according to the literature to induce a ferromagnetic behavior, in addition to confirming the results obtained using XRD. The magnetic properties were also studied by SQUID magnetometer. In general, the samples studied here showed a ferromagnetic behavior at 2 K with very low values of Hc and Mr and had a saturation magnetization (Ms) increases with increasing concentration of dopant ions and calcinations temperature. It was observed a weak ferromagnetism at room temperature too. Our results indicate that the origin of ferromagnetism is associated with formation of oxygen vacancies. Samples of mixed matrix doped iron showed an interesting change in behavior. When the concentration of dopant ions was x ≤ 0.04 the samples were ferromagnetic when the concentration was x ≥ 0.05 it showed antiferromagnetic with Néel temperature approximately equal to 12, 27 and 13 K for Fe with x = 0.05, 0.075 and 0.1, respectively.Neste trabalho estudamos a caracterização estrutural e magnética das amostras de Ce1-2xZnxMxO2-o (Fe, Co e Ni) e Ce0,5(1-x)Zn0,5(1-x)FexO2-o obtidas via processo sol-gel proteico que tem como precursor orgânico a água de coco. As soluções foram preparadas pela dissolução dos nitratos de cério e zinco para as amostras dopadas com Zn e nitratos de cério, zinco e cobalto ou ferro para as amostras dopadas com Zn, Fe ou Co e, posteriormente, foram levadas a estufa a 100ºC/24 h para formação do xerogel. A seguir as amostras foram calcinadas a 400, 600, 800 e 1000 ºC/2h hora em ar. Após calcinação foram feitas análises de difratometria de raios X (DRX) para identificação das fases e estimar o limite de solubilidade para os sistemas estudados. Através das medidas de espectroscopia Raman identificou-se a presença de lacunas de oxigênio que segundo a literatura induzem um comportamento ferromagnético, além de confirmar os resultados obtidos via DRX. As propriedades magnéticas também foram estudadas por magnetometria SQUID. De uma forma geral, as amostras apresentaram um comportamento ferromagnético a 2 K com valores muito baixos de campo coercivo (Hc) e magnetização remanente (Mr) e apresentaram uma magnetização (Ms) que aumenta linearmente com a concentração de íons dopantes e da temperatura de calcinação. Foi observado também um fraco ferromagnetismo (FM) a temperatura ambiente. Os nossos resultados dão indícios de que a origem do ferromagnetismo está associada à formação de lacunas de oxigênio. As amostras da matriz mista dopada com ferro apresentaram uma interessante mudança de comportamento. Quando a concentração nominal dos íons dopantes foi x ≤ 0,04 as amostras apresentaram-se ferromagnéticas quando a concentração foi x ≥ 0,05 elas se mostraram antiferromagnéticas (AFM) com temperatura de Néel (Tn) aproximadamente igual a 12, 27 e 13 K para concentrações nominais de Fe x = 0,05, 0,075 e 0,1, respectivamente.Coordenação de Aperfeiçoamento de Pessoal de Nível Superiorapplication/pdfporUniversidade Federal de SergipePós-Graduação em FísicaUFSBRMagnetismoDifratometriaEspectroscopiaMagnetismSpectroscopyDiffractionCNPQ::CIENCIAS EXATAS E DA TERRA::FISICAFerromagnetismo diluído de semicondutores mistos CeO2-ZnO:M (M = Fe, Co, Ni)info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/doctoralThesisinfo:eu-repo/semantics/openAccessreponame:Repositório Institucional da UFSinstname:Universidade Federal de Sergipe (UFS)instacron:UFSORIGINALTAMARA_SIBELE_SANTOS.pdfapplication/pdf3700096https://ri.ufs.br/jspui/bitstream/riufs/5238/1/TAMARA_SIBELE_SANTOS.pdf418b44b8ebb2bcf0024d6a2c2c17d5c6MD51TEXTTAMARA_SIBELE_SANTOS.pdf.txtTAMARA_SIBELE_SANTOS.pdf.txtExtracted texttext/plain184545https://ri.ufs.br/jspui/bitstream/riufs/5238/2/TAMARA_SIBELE_SANTOS.pdf.txtbf480f5d877100dca359bc6f8e935d22MD52THUMBNAILTAMARA_SIBELE_SANTOS.pdf.jpgTAMARA_SIBELE_SANTOS.pdf.jpgGenerated Thumbnailimage/jpeg1198https://ri.ufs.br/jspui/bitstream/riufs/5238/3/TAMARA_SIBELE_SANTOS.pdf.jpg255eeb11dc46d9f210e19aa700ef65e7MD53riufs/52382018-06-13 20:04:02.636oai:ufs.br:riufs/5238Repositório InstitucionalPUBhttps://ri.ufs.br/oai/requestrepositorio@academico.ufs.bropendoar:2018-06-13T23:04:02Repositório Institucional da UFS - Universidade Federal de Sergipe (UFS)false |
dc.title.por.fl_str_mv |
Ferromagnetismo diluído de semicondutores mistos CeO2-ZnO:M (M = Fe, Co, Ni) |
title |
Ferromagnetismo diluído de semicondutores mistos CeO2-ZnO:M (M = Fe, Co, Ni) |
spellingShingle |
Ferromagnetismo diluído de semicondutores mistos CeO2-ZnO:M (M = Fe, Co, Ni) Santos, Tâmara Sibele dos Magnetismo Difratometria Espectroscopia Magnetism Spectroscopy Diffraction CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA |
title_short |
Ferromagnetismo diluído de semicondutores mistos CeO2-ZnO:M (M = Fe, Co, Ni) |
title_full |
Ferromagnetismo diluído de semicondutores mistos CeO2-ZnO:M (M = Fe, Co, Ni) |
title_fullStr |
Ferromagnetismo diluído de semicondutores mistos CeO2-ZnO:M (M = Fe, Co, Ni) |
title_full_unstemmed |
Ferromagnetismo diluído de semicondutores mistos CeO2-ZnO:M (M = Fe, Co, Ni) |
title_sort |
Ferromagnetismo diluído de semicondutores mistos CeO2-ZnO:M (M = Fe, Co, Ni) |
author |
Santos, Tâmara Sibele dos |
author_facet |
Santos, Tâmara Sibele dos |
author_role |
author |
dc.contributor.author.fl_str_mv |
Santos, Tâmara Sibele dos |
dc.contributor.advisor1Lattes.fl_str_mv |
http://lattes.cnpq.br/3264248290660253 |
dc.contributor.advisor1.fl_str_mv |
Macêdo, Marcelo Andrade |
contributor_str_mv |
Macêdo, Marcelo Andrade |
dc.subject.por.fl_str_mv |
Magnetismo Difratometria Espectroscopia |
topic |
Magnetismo Difratometria Espectroscopia Magnetism Spectroscopy Diffraction CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA |
dc.subject.eng.fl_str_mv |
Magnetism Spectroscopy Diffraction |
dc.subject.cnpq.fl_str_mv |
CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA |
description |
In this paper we study the structural and magnetic characterization of samples CeO2, CeO2-Zn and ZnO: M (Fe, Co, Ni) obtained via the proteic sol-gel process, where the organic precursor is coconut water. The solutions were prepared by dissolving cerium nitrate and nitrate zinc for samples doped with Zn and cerium nitrate, zinc and cobalt or iron in the samples doped with Fe or Co and were later brought the muffle where they remained for 24 h at 100 º C to form the xerogel. Then the samples were calcined at 400, 600, 800 and 1000 º C for one hour in air. After calcinations the powders were analyzed in the X-ray diffraction to identify the phases formed and to infer a limit of solubility for the systems studied. By measuring the Raman spectroscopy identified the presence of oxygen vacancies according to the literature to induce a ferromagnetic behavior, in addition to confirming the results obtained using XRD. The magnetic properties were also studied by SQUID magnetometer. In general, the samples studied here showed a ferromagnetic behavior at 2 K with very low values of Hc and Mr and had a saturation magnetization (Ms) increases with increasing concentration of dopant ions and calcinations temperature. It was observed a weak ferromagnetism at room temperature too. Our results indicate that the origin of ferromagnetism is associated with formation of oxygen vacancies. Samples of mixed matrix doped iron showed an interesting change in behavior. When the concentration of dopant ions was x ≤ 0.04 the samples were ferromagnetic when the concentration was x ≥ 0.05 it showed antiferromagnetic with Néel temperature approximately equal to 12, 27 and 13 K for Fe with x = 0.05, 0.075 and 0.1, respectively. |
publishDate |
2012 |
dc.date.issued.fl_str_mv |
2012-02-24 |
dc.date.accessioned.fl_str_mv |
2017-09-26T18:23:44Z |
dc.date.available.fl_str_mv |
2017-09-26T18:23:44Z |
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.uri.fl_str_mv |
https://ri.ufs.br/handle/riufs/5238 |
url |
https://ri.ufs.br/handle/riufs/5238 |
dc.language.iso.fl_str_mv |
por |
language |
por |
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 Sergipe |
dc.publisher.program.fl_str_mv |
Pós-Graduação em Física |
dc.publisher.initials.fl_str_mv |
UFS |
dc.publisher.country.fl_str_mv |
BR |
publisher.none.fl_str_mv |
Universidade Federal de Sergipe |
dc.source.none.fl_str_mv |
reponame:Repositório Institucional da UFS instname:Universidade Federal de Sergipe (UFS) instacron:UFS |
instname_str |
Universidade Federal de Sergipe (UFS) |
instacron_str |
UFS |
institution |
UFS |
reponame_str |
Repositório Institucional da UFS |
collection |
Repositório Institucional da UFS |
bitstream.url.fl_str_mv |
https://ri.ufs.br/jspui/bitstream/riufs/5238/1/TAMARA_SIBELE_SANTOS.pdf https://ri.ufs.br/jspui/bitstream/riufs/5238/2/TAMARA_SIBELE_SANTOS.pdf.txt https://ri.ufs.br/jspui/bitstream/riufs/5238/3/TAMARA_SIBELE_SANTOS.pdf.jpg |
bitstream.checksum.fl_str_mv |
418b44b8ebb2bcf0024d6a2c2c17d5c6 bf480f5d877100dca359bc6f8e935d22 255eeb11dc46d9f210e19aa700ef65e7 |
bitstream.checksumAlgorithm.fl_str_mv |
MD5 MD5 MD5 |
repository.name.fl_str_mv |
Repositório Institucional da UFS - Universidade Federal de Sergipe (UFS) |
repository.mail.fl_str_mv |
repositorio@academico.ufs.br |
_version_ |
1793351111804977152 |