Síntese, caracterização de ferritas espinélio com propriedades magnéticas e absorvedoras de microondas
Autor(a) principal: | |
---|---|
Data de Publicação: | 2013 |
Tipo de documento: | Tese |
Idioma: | por |
Título da fonte: | Repositório Institucional da UFRN |
Texto Completo: | https://repositorio.ufrn.br/jspui/handle/123456789/17768 |
Resumo: | Were synthesized spinel-type ferrites with general formula Ni0,8Mg0.2-xMxFe2O4, where M represents the doping Mn, Co or Mn + Co simultaneously, x ranges for the values 0.02, 0.05 and 0.1. The value of x was divided by 2 in cases where M equals Mn and Co conjugates. We used the citrate precursor method and heat treatment to obtain the phases at 1100°C. The materials were characterized by XRD, TGA/ DTGA, SEM, MAV and reflectivity measurements by the method of waveguide. Powders to 350°C/3.5 h were crystalline and nanosized. According to the results this temperature all powders have a percentage of ferrite phase over 90%. The composition had the addition of Mn and Co simultaneously showed a higher percentage of secondary phase NiO, 5.8%. The TGA/DTGA curves indicate that this sample reached phase (s) crystalline (s) at lowest temperatures. The X-ray diffractograms of the samples calcined at 350°C and 1100°C were treated with the Rietveld refinament technique. The powders calcined at 1100 °C/3h in air show to be 100% except spinel phase composition with 0.02 doping. The micrographs show clusters of particles with sizes smaller than 1 μm in calcination temperature of 1100°C which agreed with the result of Rietveld refinement. In the compositions doped with Mn were higher values of magnetization (45.90 and 53.20 Am2/kg), which did not cause high microwave absorption. The theoretical calculation of magnetization (MT) was consistent with the results, considering that there was agreement between the increase of magnetization experimental and theoretical. It was observed that there was the interrelation of the final effect of absorption with the thickness of MARE, the composition of ferrimagnetic materials and in particular the specific values of frequency. The analysis shows that the reflectivity increases in the concentration of cobalt increased the frequency range and also for absorption 10.17 GHz and 84%, respectively. The best result of chemical homogeneity and the value of 2.96 x 10-2 tesla coercive field were crucial for high performance ferrite absorber with 0.1 cobalt. The Cobalt has high magnetocrystalline anisotropy, it is associated with an increased coercive field, Hc. Therefore, this property improves the results of reflectivity of spinel ferrites |
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Silva, José Eves Mendes dahttp://lattes.cnpq.br/6614738245733047http://lattes.cnpq.br/9213856023536973Araújo, José Humberto dehttp://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4785558U2Rezende, Mirabel Cerqueirahttp://lattes.cnpq.br/3744737176516322Lima, Ulisandra Ribeiro dehttp://lattes.cnpq.br/0610156933803056Acchar, Wilsonhttp://lattes.cnpq.br/5460040602567184Nasar, Ricardo Silveira2014-12-17T15:42:21Z2014-01-022014-12-17T15:42:21Z2013-03-08SILVA, José Eves Mendes da. Síntese, caracterização de ferritas espinélio com propriedades magnéticas e absorvedoras de microondas. 2013. 138 f. Tese (Doutorado em Físico-Química; Química) - Universidade Federal do Rio Grande do Norte, Natal, 2013.https://repositorio.ufrn.br/jspui/handle/123456789/17768Were synthesized spinel-type ferrites with general formula Ni0,8Mg0.2-xMxFe2O4, where M represents the doping Mn, Co or Mn + Co simultaneously, x ranges for the values 0.02, 0.05 and 0.1. The value of x was divided by 2 in cases where M equals Mn and Co conjugates. We used the citrate precursor method and heat treatment to obtain the phases at 1100°C. The materials were characterized by XRD, TGA/ DTGA, SEM, MAV and reflectivity measurements by the method of waveguide. Powders to 350°C/3.5 h were crystalline and nanosized. According to the results this temperature all powders have a percentage of ferrite phase over 90%. The composition had the addition of Mn and Co simultaneously showed a higher percentage of secondary phase NiO, 5.8%. The TGA/DTGA curves indicate that this sample reached phase (s) crystalline (s) at lowest temperatures. The X-ray diffractograms of the samples calcined at 350°C and 1100°C were treated with the Rietveld refinament technique. The powders calcined at 1100 °C/3h in air show to be 100% except spinel phase composition with 0.02 doping. The micrographs show clusters of particles with sizes smaller than 1 μm in calcination temperature of 1100°C which agreed with the result of Rietveld refinement. In the compositions doped with Mn were higher values of magnetization (45.90 and 53.20 Am2/kg), which did not cause high microwave absorption. The theoretical calculation of magnetization (MT) was consistent with the results, considering that there was agreement between the increase of magnetization experimental and theoretical. It was observed that there was the interrelation of the final effect of absorption with the thickness of MARE, the composition of ferrimagnetic materials and in particular the specific values of frequency. The analysis shows that the reflectivity increases in the concentration of cobalt increased the frequency range and also for absorption 10.17 GHz and 84%, respectively. The best result of chemical homogeneity and the value of 2.96 x 10-2 tesla coercive field were crucial for high performance ferrite absorber with 0.1 cobalt. The Cobalt has high magnetocrystalline anisotropy, it is associated with an increased coercive field, Hc. Therefore, this property improves the results of reflectivity of spinel ferritesForam sintetizadas ferritas do tipo espinélio com fórmula geral Ni0,8Mg0,2-xMxFe2O4, onde M representa os dopantes Mn, Co ou Mn + Co simultaneamente, x varia para os valores 0,02; 0,05 e 0,1. O valor de x foi dividido por 2 nos casos em que M equivale a Mn com Co conjugados. Foi utilizado o método dos citratos precursores e tratamento térmico na obtenção das fases a 1100°C. Os materiais foram caracterizados por DRX, TGA/DTGA, MEV, MAV e medidas de refletividade pelo método de guia de ondas. Os pós a 350°C/3,5h foram cristalinos e nanométricos. De acordo com os resultados nesta temperatura todos os pós apresentam um percentual de fase ferrita superior a 90%. A composição que teve a adição de Mn e Co simultaneamente apresentou maior percentual de fase secundária NiO, 5,8%. As curvas TGA/DTGA indicam que essa amostra alcançou fase(s) cristalina(s) em temperaturas mais baixas. Os difratogramas de raios X das amostras calcinadas a 350°C e 1100°C foram tratados pela técnica de refinamento Rietveld. Os pós calcinados a 1100°C/3h em atmosfera ambiente mostram ser 100% de fase espinélio exceto a composição com 0,02 de dopantes. As micrografias apresentam aglomerados de partículas com tamanhos menores que 1 μm na temperatura de calcinação de 1100°C, o que concordou com o resultado de refinamento Rietveld. Nas composições dopadas com Mn ocorreram os maiores valores de magnetização (45,90 e 53,20 Am2/kg), o que não acarretou alta absorção de microondas. O cálculo teórico da magnetização (MT) foi coerente com os resultados, considerando-se que houve concordância entre o aumento das magnetizações experimental e teórica. Observa-se que houve interrelação do efeito final de absorção com a espessura do MARE, a composição do material ferrimagnético em particular e os valores específicos de freqüência. A análise de refletividade indica que o aumento na concentração de cobalto aumentou a faixa de freqüência e a absorção para 10,17 GHz e 84%, respectivamente. O resultado indica que a melhor homogeneidade química e o valor 2,96 x 10-2 tesla de campo coercitivo foram determinantes para o alto desempenho absorvedor da ferrita com 0,1 de cobalto. O Cobalto tem alta anisotropia magnetocristalina, isto está associado ao aumento do campo coercitivo, Hc. Portanto, essa propriedade melhora os resultados de refletividade das ferritas espinélioCoordenação de Aperfeiçoamento de Pessoal de Nível Superiorapplication/pdfporUniversidade Federal do Rio Grande do NortePrograma de Pós-Graduação em QuímicaUFRNBRFísico-Química; QuímicaFerrita espinélio. Citratos precursores. Material magnético absorvedor de radiação.Ferrite spinel. Citrates precursors. Magnetic material. Radiation absorberCNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICASíntese, caracterização de ferritas espinélio com propriedades magnéticas e absorvedoras de microondasinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/doctoralThesisinfo:eu-repo/semantics/openAccessreponame:Repositório Institucional da UFRNinstname:Universidade Federal do Rio Grande do Norte (UFRN)instacron:UFRNORIGINALJoseEMS_TESE.pdfapplication/pdf5374821https://repositorio.ufrn.br/bitstream/123456789/17768/1/JoseEMS_TESE.pdf56fe60cd3bbf0a42f7512c62fe5b976eMD51TEXTJoseEMS_TESE.pdf.txtJoseEMS_TESE.pdf.txtExtracted texttext/plain223632https://repositorio.ufrn.br/bitstream/123456789/17768/6/JoseEMS_TESE.pdf.txt2c6aa6917a5ccdd70df21c38411ae2a1MD56THUMBNAILJoseEMS_TESE.pdf.jpgJoseEMS_TESE.pdf.jpgIM Thumbnailimage/jpeg5345https://repositorio.ufrn.br/bitstream/123456789/17768/7/JoseEMS_TESE.pdf.jpg76b7d259237b21caef602dd664b8ccf4MD57123456789/177682017-11-04 15:24:24.565oai:https://repositorio.ufrn.br:123456789/17768Repositório de PublicaçõesPUBhttp://repositorio.ufrn.br/oai/opendoar:2017-11-04T18:24:24Repositório Institucional da UFRN - Universidade Federal do Rio Grande do Norte (UFRN)false |
dc.title.por.fl_str_mv |
Síntese, caracterização de ferritas espinélio com propriedades magnéticas e absorvedoras de microondas |
title |
Síntese, caracterização de ferritas espinélio com propriedades magnéticas e absorvedoras de microondas |
spellingShingle |
Síntese, caracterização de ferritas espinélio com propriedades magnéticas e absorvedoras de microondas Silva, José Eves Mendes da Ferrita espinélio. Citratos precursores. Material magnético absorvedor de radiação. Ferrite spinel. Citrates precursors. Magnetic material. Radiation absorber CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA |
title_short |
Síntese, caracterização de ferritas espinélio com propriedades magnéticas e absorvedoras de microondas |
title_full |
Síntese, caracterização de ferritas espinélio com propriedades magnéticas e absorvedoras de microondas |
title_fullStr |
Síntese, caracterização de ferritas espinélio com propriedades magnéticas e absorvedoras de microondas |
title_full_unstemmed |
Síntese, caracterização de ferritas espinélio com propriedades magnéticas e absorvedoras de microondas |
title_sort |
Síntese, caracterização de ferritas espinélio com propriedades magnéticas e absorvedoras de microondas |
author |
Silva, José Eves Mendes da |
author_facet |
Silva, José Eves Mendes da |
author_role |
author |
dc.contributor.authorID.por.fl_str_mv |
|
dc.contributor.authorLattes.por.fl_str_mv |
http://lattes.cnpq.br/6614738245733047 |
dc.contributor.advisorID.por.fl_str_mv |
|
dc.contributor.advisorLattes.por.fl_str_mv |
http://lattes.cnpq.br/9213856023536973 |
dc.contributor.referees1.pt_BR.fl_str_mv |
Araújo, José Humberto de |
dc.contributor.referees1ID.por.fl_str_mv |
|
dc.contributor.referees1Lattes.por.fl_str_mv |
http://buscatextual.cnpq.br/buscatextual/visualizacv.do?id=K4785558U2 |
dc.contributor.referees2.pt_BR.fl_str_mv |
Rezende, Mirabel Cerqueira |
dc.contributor.referees2ID.por.fl_str_mv |
|
dc.contributor.referees2Lattes.por.fl_str_mv |
http://lattes.cnpq.br/3744737176516322 |
dc.contributor.referees3.pt_BR.fl_str_mv |
Lima, Ulisandra Ribeiro de |
dc.contributor.referees3ID.por.fl_str_mv |
|
dc.contributor.referees3Lattes.por.fl_str_mv |
http://lattes.cnpq.br/0610156933803056 |
dc.contributor.referees4.pt_BR.fl_str_mv |
Acchar, Wilson |
dc.contributor.referees4ID.por.fl_str_mv |
|
dc.contributor.referees4Lattes.por.fl_str_mv |
http://lattes.cnpq.br/5460040602567184 |
dc.contributor.author.fl_str_mv |
Silva, José Eves Mendes da |
dc.contributor.advisor1.fl_str_mv |
Nasar, Ricardo Silveira |
contributor_str_mv |
Nasar, Ricardo Silveira |
dc.subject.por.fl_str_mv |
Ferrita espinélio. Citratos precursores. Material magnético absorvedor de radiação. |
topic |
Ferrita espinélio. Citratos precursores. Material magnético absorvedor de radiação. Ferrite spinel. Citrates precursors. Magnetic material. Radiation absorber CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA |
dc.subject.eng.fl_str_mv |
Ferrite spinel. Citrates precursors. Magnetic material. Radiation absorber |
dc.subject.cnpq.fl_str_mv |
CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA |
description |
Were synthesized spinel-type ferrites with general formula Ni0,8Mg0.2-xMxFe2O4, where M represents the doping Mn, Co or Mn + Co simultaneously, x ranges for the values 0.02, 0.05 and 0.1. The value of x was divided by 2 in cases where M equals Mn and Co conjugates. We used the citrate precursor method and heat treatment to obtain the phases at 1100°C. The materials were characterized by XRD, TGA/ DTGA, SEM, MAV and reflectivity measurements by the method of waveguide. Powders to 350°C/3.5 h were crystalline and nanosized. According to the results this temperature all powders have a percentage of ferrite phase over 90%. The composition had the addition of Mn and Co simultaneously showed a higher percentage of secondary phase NiO, 5.8%. The TGA/DTGA curves indicate that this sample reached phase (s) crystalline (s) at lowest temperatures. The X-ray diffractograms of the samples calcined at 350°C and 1100°C were treated with the Rietveld refinament technique. The powders calcined at 1100 °C/3h in air show to be 100% except spinel phase composition with 0.02 doping. The micrographs show clusters of particles with sizes smaller than 1 μm in calcination temperature of 1100°C which agreed with the result of Rietveld refinement. In the compositions doped with Mn were higher values of magnetization (45.90 and 53.20 Am2/kg), which did not cause high microwave absorption. The theoretical calculation of magnetization (MT) was consistent with the results, considering that there was agreement between the increase of magnetization experimental and theoretical. It was observed that there was the interrelation of the final effect of absorption with the thickness of MARE, the composition of ferrimagnetic materials and in particular the specific values of frequency. The analysis shows that the reflectivity increases in the concentration of cobalt increased the frequency range and also for absorption 10.17 GHz and 84%, respectively. The best result of chemical homogeneity and the value of 2.96 x 10-2 tesla coercive field were crucial for high performance ferrite absorber with 0.1 cobalt. The Cobalt has high magnetocrystalline anisotropy, it is associated with an increased coercive field, Hc. Therefore, this property improves the results of reflectivity of spinel ferrites |
publishDate |
2013 |
dc.date.issued.fl_str_mv |
2013-03-08 |
dc.date.accessioned.fl_str_mv |
2014-12-17T15:42:21Z |
dc.date.available.fl_str_mv |
2014-01-02 2014-12-17T15:42:21Z |
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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 |
SILVA, José Eves Mendes da. Síntese, caracterização de ferritas espinélio com propriedades magnéticas e absorvedoras de microondas. 2013. 138 f. Tese (Doutorado em Físico-Química; Química) - Universidade Federal do Rio Grande do Norte, Natal, 2013. |
dc.identifier.uri.fl_str_mv |
https://repositorio.ufrn.br/jspui/handle/123456789/17768 |
identifier_str_mv |
SILVA, José Eves Mendes da. Síntese, caracterização de ferritas espinélio com propriedades magnéticas e absorvedoras de microondas. 2013. 138 f. Tese (Doutorado em Físico-Química; Química) - Universidade Federal do Rio Grande do Norte, Natal, 2013. |
url |
https://repositorio.ufrn.br/jspui/handle/123456789/17768 |
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por |
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Universidade Federal do Rio Grande do Norte |
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Programa de Pós-Graduação em Química |
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UFRN |
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BR |
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Físico-Química; Química |
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Universidade Federal do Rio Grande do Norte |
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