Estudo do efeito magnetocalórico e barocalórico de sistemas magnéticos baseados em Mn
Autor(a) principal: | |
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Data de Publicação: | 2017 |
Tipo de documento: | Tese |
Idioma: | por |
Título da fonte: | Repositório Institucional da UFS |
Texto Completo: | https://ri.ufs.br/handle/riufs/5277 |
Resumo: | In this work we detail the magnetoelastic coupling method in which the elastic term is absorbed by the exchange term allowing it to obtain additional contributions, Sadd, to the total entropy variation, by means of the dependence of the exchange parameter (T;H; P). For this purpose, we proposed the dependence of the bulk modulus with temperature, B(T), for the linear case (L-case) and Wachtman type (W-case), thus verifying that the total entropy variation , SMaxwell, is the sum of the conventional entropy variation, Sconv, with the additional contribution, that is, SMaxwell = Sconv + Sadd. In addition, we analyzed: i) the action of hydrostatic pressure on magnetic and magnetocaloric properties for both L and W cases, where there was a reduction in transition temperature, TC, a change in nature of the magnetic transition and the increase in the intensity of the magnetocaloric e ect, Siso, keeping constant the area under the curves, with increasing pressure; (ii) the action of the magnetic eld on the barocaloric properties, where an increase in TC and a reduction of the barocaloric e ect, bar iso , could be observed, constant keeping the area under the curves, with the increase of the magnetic eld, thus verifying that the barocaloric e ect is energetically more e cient under the action of low elds than the magnetocaloric e ect; and (iii) the action of the magnetic eld and the pressure simultaneously, verifying an alternative way to potentiate the magnetocaloric e ect for a wide temperature range, which makes possible to apply the results to other systems besides MnAs and their parents. Finally, an extension of the Kubo and Ohata model, similar to Bean-Rodbell, was presented for the manganites, La1-xCaxMnO3 and La2=3(Ca1-xSrx)1=3MnO3, in the presence of magnetic eld, thus describing its magnetic, magnetocaloric, barocaloric and structural properties, by means of such magnitudes as: magnetization, variation of magnetic entropy, deformation, double exchange energy and electron conduction bandwidth eg, thus showing the connectivity between these quantities in the description of the physical properties of these compounds and showing an alternative model in the theoretical study of these manganites of Lanthanum. |
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Silva Júnior, José Almeida daPlaza, Edison Jesús Ramírezhttp://lattes.cnpq.br/35906843598391232017-09-26T18:24:01Z2017-09-26T18:24:01Z2017-03-16SILVA JÚNIOR, José Almeida da. Estudo do efeito magnetocalórico e barocalórico de sistemas magnéticos baseados em Mn. 2017. 102 f. Tese (Pós-Graduação em Física) - Universidade Federal de Sergipe, São Cristóvão, SE, 2017.https://ri.ufs.br/handle/riufs/5277In this work we detail the magnetoelastic coupling method in which the elastic term is absorbed by the exchange term allowing it to obtain additional contributions, Sadd, to the total entropy variation, by means of the dependence of the exchange parameter (T;H; P). For this purpose, we proposed the dependence of the bulk modulus with temperature, B(T), for the linear case (L-case) and Wachtman type (W-case), thus verifying that the total entropy variation , SMaxwell, is the sum of the conventional entropy variation, Sconv, with the additional contribution, that is, SMaxwell = Sconv + Sadd. In addition, we analyzed: i) the action of hydrostatic pressure on magnetic and magnetocaloric properties for both L and W cases, where there was a reduction in transition temperature, TC, a change in nature of the magnetic transition and the increase in the intensity of the magnetocaloric e ect, Siso, keeping constant the area under the curves, with increasing pressure; (ii) the action of the magnetic eld on the barocaloric properties, where an increase in TC and a reduction of the barocaloric e ect, bar iso , could be observed, constant keeping the area under the curves, with the increase of the magnetic eld, thus verifying that the barocaloric e ect is energetically more e cient under the action of low elds than the magnetocaloric e ect; and (iii) the action of the magnetic eld and the pressure simultaneously, verifying an alternative way to potentiate the magnetocaloric e ect for a wide temperature range, which makes possible to apply the results to other systems besides MnAs and their parents. Finally, an extension of the Kubo and Ohata model, similar to Bean-Rodbell, was presented for the manganites, La1-xCaxMnO3 and La2=3(Ca1-xSrx)1=3MnO3, in the presence of magnetic eld, thus describing its magnetic, magnetocaloric, barocaloric and structural properties, by means of such magnitudes as: magnetization, variation of magnetic entropy, deformation, double exchange energy and electron conduction bandwidth eg, thus showing the connectivity between these quantities in the description of the physical properties of these compounds and showing an alternative model in the theoretical study of these manganites of Lanthanum.Neste trabalho de pesquisa detalhamos o m etodo de acoplamento magnetoel astico no qual o termo el astico e absorvido pelo termo de troca possibilitando obter contribui c~oes adicionais, Sadd, a varia c~ao de entropia total, por meio da depend^encia do par^ametro de troca (T;H; P). Com esta nalidade, se prop^os a depend^encia do m odulo de volume com a temperatura, B(T), para o caso linear (caso-L) e do tipo Wachtman (caso-W), veri - cando assim que a varia c~ao de entropia total, SMaxwell, e a soma da varia c~ao de entropia convencional, Sconv, com a contribui c~ao adicional, ou seja, SMaxwell = Sconv+ Sadd. Al em disso, analisou-se: i) a a c~ao da press~ao hidrost atica nas propriedades magn eticas e magnetocal oricas para ambos os casos, L e W, onde veri cou-se uma redu c~ao na temperatura de transi c~ao, TC, uma mudan ca na natureza da transi c~ao magn etica e o aumento na intensidade do efeito magnetocal orico, Siso, mantendo a area sob as curvas constante, com o aumento da press~ao; ii) a a c~ao do campo magn etico nas propriedades barocal oricas, onde constatou-se um aumento em TC e uma redu c~ao do efeito barocal orico, Sbar iso , mantendo a area sob as curvas constante, com o aumento do campo magn etico, veri cando assim que o efeito barocal orico e energeticamente mais e ciente sob a c~ao de baixos campos do que o efeito magnetocal orico; e iii) a a c~ao do campo magn etico e da press~ao de forma simult^anea, veri cando uma forma alternativa de potencializar o efeito magnetocal orico para uma larga faixa de temperatura, sendo poss vel aplicar os resultados a outros sistemas, al em do MnAs e seus parentes. Por m, apresentou-se uma exten c~ao do modelo de Kubo e Ohata, similar ao de Bean-Rodbell, para as manganitas, La1-xCaxMnO3 e La2=3(Ca1-xSrx)1=3MnO3, em presen ca de campo magn etico, descrevendo assim as suas propriedades magn eticas, magnetocal oricas, barocal oricas e estruturais, por meio de grandezas como: magnetiza c~ao, varia c~ao de entropia magn etica, deforma c~ao, energia de dupla troca e largura da banda de condu c~ao dos el etrons eg, evid^enciando desta forma, a conectividade entre essas grandezas na descri c~ao das propriedades f sicas desses compostos e apresentando um modelo alternativo no estudo te orico destas manganitas de Lant^anio.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPESapplication/pdfporUniversidade Federal de SergipePós-Graduação em FísicaUFSBrasilFísicaMagnetismoParamagnetismoFerromagnetismoTermodinâmicaEntropiaEfeitos magnetotérmicosPropriedades magnetotérmicasÓxidos metálicosManganitasAcoplamento magnetoelásticoMagnetocalóricoBarocalóricoBean-RodbellMagnetoelastic couplingEntropyMagnetocaloricBarocaloricManganitesCIENCIAS EXATAS E DA TERRA::FISICAEstudo do efeito magnetocalórico e barocalórico de sistemas magnéticos baseados em Mninfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/doctoralThesisinfo:eu-repo/semantics/openAccessreponame:Repositório Institucional da UFSinstname:Universidade Federal de Sergipe (UFS)instacron:UFSORIGINALJOSE_ALMEIDA_SILVA_JUNIOR.pdfapplication/pdf14408832https://ri.ufs.br/jspui/bitstream/riufs/5277/1/JOSE_ALMEIDA_SILVA_JUNIOR.pdf9503a530d7e6a9c45f434f945ae75363MD51TEXTJOSE_ALMEIDA_SILVA_JUNIOR.pdf.txtJOSE_ALMEIDA_SILVA_JUNIOR.pdf.txtExtracted texttext/plain190279https://ri.ufs.br/jspui/bitstream/riufs/5277/2/JOSE_ALMEIDA_SILVA_JUNIOR.pdf.txtc205780e20ee643223d234bc1a79f1c7MD52THUMBNAILJOSE_ALMEIDA_SILVA_JUNIOR.pdf.jpgJOSE_ALMEIDA_SILVA_JUNIOR.pdf.jpgGenerated Thumbnailimage/jpeg1277https://ri.ufs.br/jspui/bitstream/riufs/5277/3/JOSE_ALMEIDA_SILVA_JUNIOR.pdf.jpgcd855dba68f8ff75a264b309d945b964MD53riufs/52772018-06-12 19:46:22.418oai:ufs.br:riufs/5277Repositório InstitucionalPUBhttps://ri.ufs.br/oai/requestrepositorio@academico.ufs.bropendoar:2018-06-12T22:46:22Repositório Institucional da UFS - Universidade Federal de Sergipe (UFS)false |
dc.title.por.fl_str_mv |
Estudo do efeito magnetocalórico e barocalórico de sistemas magnéticos baseados em Mn |
title |
Estudo do efeito magnetocalórico e barocalórico de sistemas magnéticos baseados em Mn |
spellingShingle |
Estudo do efeito magnetocalórico e barocalórico de sistemas magnéticos baseados em Mn Silva Júnior, José Almeida da Física Magnetismo Paramagnetismo Ferromagnetismo Termodinâmica Entropia Efeitos magnetotérmicos Propriedades magnetotérmicas Óxidos metálicos Manganitas Acoplamento magnetoelástico Magnetocalórico Barocalórico Bean-Rodbell Magnetoelastic coupling Entropy Magnetocaloric Barocaloric Manganites CIENCIAS EXATAS E DA TERRA::FISICA |
title_short |
Estudo do efeito magnetocalórico e barocalórico de sistemas magnéticos baseados em Mn |
title_full |
Estudo do efeito magnetocalórico e barocalórico de sistemas magnéticos baseados em Mn |
title_fullStr |
Estudo do efeito magnetocalórico e barocalórico de sistemas magnéticos baseados em Mn |
title_full_unstemmed |
Estudo do efeito magnetocalórico e barocalórico de sistemas magnéticos baseados em Mn |
title_sort |
Estudo do efeito magnetocalórico e barocalórico de sistemas magnéticos baseados em Mn |
author |
Silva Júnior, José Almeida da |
author_facet |
Silva Júnior, José Almeida da |
author_role |
author |
dc.contributor.author.fl_str_mv |
Silva Júnior, José Almeida da |
dc.contributor.advisor1.fl_str_mv |
Plaza, Edison Jesús Ramírez |
dc.contributor.authorLattes.fl_str_mv |
http://lattes.cnpq.br/3590684359839123 |
contributor_str_mv |
Plaza, Edison Jesús Ramírez |
dc.subject.por.fl_str_mv |
Física Magnetismo Paramagnetismo Ferromagnetismo Termodinâmica Entropia Efeitos magnetotérmicos Propriedades magnetotérmicas Óxidos metálicos Manganitas Acoplamento magnetoelástico Magnetocalórico Barocalórico Bean-Rodbell |
topic |
Física Magnetismo Paramagnetismo Ferromagnetismo Termodinâmica Entropia Efeitos magnetotérmicos Propriedades magnetotérmicas Óxidos metálicos Manganitas Acoplamento magnetoelástico Magnetocalórico Barocalórico Bean-Rodbell Magnetoelastic coupling Entropy Magnetocaloric Barocaloric Manganites CIENCIAS EXATAS E DA TERRA::FISICA |
dc.subject.eng.fl_str_mv |
Magnetoelastic coupling Entropy Magnetocaloric Barocaloric Manganites |
dc.subject.cnpq.fl_str_mv |
CIENCIAS EXATAS E DA TERRA::FISICA |
description |
In this work we detail the magnetoelastic coupling method in which the elastic term is absorbed by the exchange term allowing it to obtain additional contributions, Sadd, to the total entropy variation, by means of the dependence of the exchange parameter (T;H; P). For this purpose, we proposed the dependence of the bulk modulus with temperature, B(T), for the linear case (L-case) and Wachtman type (W-case), thus verifying that the total entropy variation , SMaxwell, is the sum of the conventional entropy variation, Sconv, with the additional contribution, that is, SMaxwell = Sconv + Sadd. In addition, we analyzed: i) the action of hydrostatic pressure on magnetic and magnetocaloric properties for both L and W cases, where there was a reduction in transition temperature, TC, a change in nature of the magnetic transition and the increase in the intensity of the magnetocaloric e ect, Siso, keeping constant the area under the curves, with increasing pressure; (ii) the action of the magnetic eld on the barocaloric properties, where an increase in TC and a reduction of the barocaloric e ect, bar iso , could be observed, constant keeping the area under the curves, with the increase of the magnetic eld, thus verifying that the barocaloric e ect is energetically more e cient under the action of low elds than the magnetocaloric e ect; and (iii) the action of the magnetic eld and the pressure simultaneously, verifying an alternative way to potentiate the magnetocaloric e ect for a wide temperature range, which makes possible to apply the results to other systems besides MnAs and their parents. Finally, an extension of the Kubo and Ohata model, similar to Bean-Rodbell, was presented for the manganites, La1-xCaxMnO3 and La2=3(Ca1-xSrx)1=3MnO3, in the presence of magnetic eld, thus describing its magnetic, magnetocaloric, barocaloric and structural properties, by means of such magnitudes as: magnetization, variation of magnetic entropy, deformation, double exchange energy and electron conduction bandwidth eg, thus showing the connectivity between these quantities in the description of the physical properties of these compounds and showing an alternative model in the theoretical study of these manganites of Lanthanum. |
publishDate |
2017 |
dc.date.accessioned.fl_str_mv |
2017-09-26T18:24:01Z |
dc.date.available.fl_str_mv |
2017-09-26T18:24:01Z |
dc.date.issued.fl_str_mv |
2017-03-16 |
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 |
SILVA JÚNIOR, José Almeida da. Estudo do efeito magnetocalórico e barocalórico de sistemas magnéticos baseados em Mn. 2017. 102 f. Tese (Pós-Graduação em Física) - Universidade Federal de Sergipe, São Cristóvão, SE, 2017. |
dc.identifier.uri.fl_str_mv |
https://ri.ufs.br/handle/riufs/5277 |
identifier_str_mv |
SILVA JÚNIOR, José Almeida da. Estudo do efeito magnetocalórico e barocalórico de sistemas magnéticos baseados em Mn. 2017. 102 f. Tese (Pós-Graduação em Física) - Universidade Federal de Sergipe, São Cristóvão, SE, 2017. |
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https://ri.ufs.br/handle/riufs/5277 |
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por |
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Universidade Federal de Sergipe |
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Pós-Graduação em Física |
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UFS |
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