Caracterização estrutural e magnética de cromitas produzidas pelo método de coprecipitação
Autor(a) principal: | |
---|---|
Data de Publicação: | 2016 |
Tipo de documento: | Tese |
Idioma: | por |
Título da fonte: | Repositório Institucional da UFS |
Texto Completo: | https://ri.ufs.br/handle/riufs/5259 |
Resumo: | Polycrystalline samples Mn1-xZnzCr2O4 and Cu1-xNixCr2O4 (0 x 1; 0) were produced by co-precipitation method and treated at temperatures of 400oC and 1200oC. The samples have been investigated by dc/ac magnetization as a function of temperature and magnetic field. In addition, Xray powder diffraction, X-ray fluorescence and scanning electron microscopy measurements were carried out at room temperature. The analysis results of X-ray diffraction showed that the materials are single phase. The structural refinement was carried out by the Rietveld method and cell parameters determined for these materials are consistent with those reported in the literature for bulk samples. The average particle sizes were calculated using the equation of Scherrer and compared to the sizes obtained by scanning electron microscopy. It is observed that these spinel particles have an average size of 18-55 nm. It is noted an increase in the average size with increasing calcination temperature. We study the evolution of the magnetic properties of normal spinels of the series Mn1-xZnzCr2O4 and Cu1-xNixCr2O4 through magnetic measurements with magnetometer PPMS-9T (Physical Property measurement system). Normal spinels CuCr2O4 and MnCr2O4 are ferromagnetic with Curie temperature 122 K and 43 K respectively. The zinc chromite (ZnCr2O4) which in its nano-form features an antiferromagnetic ordering with Néel temperature (TN) of 5 K, the NiCr2O4 shows two magnetic transitions, one at TC 75K related to a ferromagnetic component (longitudinal) and the second the TS 30K, associada a componente antiferromagnética (transversal). The magnetization in the system Mn1-xZnxCr2O4 for 0 x 0:5 indicates characteristics of an antiferromagnetic ordering (AF), while values of x 0:6 define the system with a typical ferrimagnetic order (FI). The behavior at the borders of AF / FI phase is indicated by the appearance of coercive field in hysteresis loops and two temperatures magnetic order. However, for other series of chromite spinel Cu1-xNixCr2O4, with x 0:5, the compounds are ferrimagnetic. In the range of 0:5 x 1:0 arise two magnetic transitions with an increased coercive field which may be associated with the emergence of components (FI) and (AF). The hysteresis cycles of the samples are clearly asymmetric, and this behavior can be attributed to the originating exchange bias effect of the presence of a ferrimagnetic and antiferromagnetic layer in the samples. In the present study we show the results of the magnetic properties of spinel chromite Mn1-xZnzCr2O4 and Cu1-xNixCr2O4 (0 x 1; 0) on a nanometric scale and bulk.EMC was investigated in three spinel type samples, when data are obtained by the measurement magnetization as function of temperature and found the change of entropy of each of them, we observe the change in the magnetic transition temperature with the applied magnetic field, but we noted not large EMC intensity values. |
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Gurgel, Thiago TarginoSalazar, Nelson Orlando Morenohttp://lattes.cnpq.br/51397555802545222017-09-26T18:23:54Z2017-09-26T18:23:54Z2016-07-26GURGEL, Thiago Targino. Caracterização estrutural e magnética de cromitas produzidas pelo método de coprecipitação. 2016. 122 f. Tese (Pós-Graduação em Física) - Universidade Federal de Sergipe, São Cristóvão, SE, 2016.https://ri.ufs.br/handle/riufs/5259Polycrystalline samples Mn1-xZnzCr2O4 and Cu1-xNixCr2O4 (0 x 1; 0) were produced by co-precipitation method and treated at temperatures of 400oC and 1200oC. The samples have been investigated by dc/ac magnetization as a function of temperature and magnetic field. In addition, Xray powder diffraction, X-ray fluorescence and scanning electron microscopy measurements were carried out at room temperature. The analysis results of X-ray diffraction showed that the materials are single phase. The structural refinement was carried out by the Rietveld method and cell parameters determined for these materials are consistent with those reported in the literature for bulk samples. The average particle sizes were calculated using the equation of Scherrer and compared to the sizes obtained by scanning electron microscopy. It is observed that these spinel particles have an average size of 18-55 nm. It is noted an increase in the average size with increasing calcination temperature. We study the evolution of the magnetic properties of normal spinels of the series Mn1-xZnzCr2O4 and Cu1-xNixCr2O4 through magnetic measurements with magnetometer PPMS-9T (Physical Property measurement system). Normal spinels CuCr2O4 and MnCr2O4 are ferromagnetic with Curie temperature 122 K and 43 K respectively. The zinc chromite (ZnCr2O4) which in its nano-form features an antiferromagnetic ordering with Néel temperature (TN) of 5 K, the NiCr2O4 shows two magnetic transitions, one at TC 75K related to a ferromagnetic component (longitudinal) and the second the TS 30K, associada a componente antiferromagnética (transversal). The magnetization in the system Mn1-xZnxCr2O4 for 0 x 0:5 indicates characteristics of an antiferromagnetic ordering (AF), while values of x 0:6 define the system with a typical ferrimagnetic order (FI). The behavior at the borders of AF / FI phase is indicated by the appearance of coercive field in hysteresis loops and two temperatures magnetic order. However, for other series of chromite spinel Cu1-xNixCr2O4, with x 0:5, the compounds are ferrimagnetic. In the range of 0:5 x 1:0 arise two magnetic transitions with an increased coercive field which may be associated with the emergence of components (FI) and (AF). The hysteresis cycles of the samples are clearly asymmetric, and this behavior can be attributed to the originating exchange bias effect of the presence of a ferrimagnetic and antiferromagnetic layer in the samples. In the present study we show the results of the magnetic properties of spinel chromite Mn1-xZnzCr2O4 and Cu1-xNixCr2O4 (0 x 1; 0) on a nanometric scale and bulk.EMC was investigated in three spinel type samples, when data are obtained by the measurement magnetization as function of temperature and found the change of entropy of each of them, we observe the change in the magnetic transition temperature with the applied magnetic field, but we noted not large EMC intensity values.Amostras policristalinas de Mn1-xZnzCr2O4 e Cu1-xNixCr2O4 (0 x 1; 0) foram produzidas pelo método de coprecipitação e tratadas em temperaturas de 400oC a 1200oC. As amostras foram caracterizadas através de medidas de difração de raios X, fluorescência de raios X, microscopia eletrônica de varredura, susceptibilidade magnética AC para diversas frequências e magnetização DC como função da temperatura e do campo magnético aplicado. Os resultados das análises dos difratogramas de raios X mostraram que os materiais são de fase única. O refinamento estrutural foi realizado pelo método de Rietveld e os parâmetros de rede determinados para estes materiais são consistentes com os reportados na literatura para a forma bulk. Os tamanhos médios dos cristalitos foram calculados usando a equação de Scherrer e comparados com os tamanhos obtidos por microscopia eletrônica de varredura. Observa-se que estes espinélios possuem cristalitos com tamanho médio de 18 a 55 nm. Nota-se um incremento do tamanho médio com o aumento da temperatura de calcinação. Estudamos a evolução das propriedades magnéticas nos espinelios normais das séries Mn1-xZnzCr2O4 e Cu1-xNixCr2O4 através de medidas magnéticas feitas com magnetômetro PPMS-9T (Physical Property Measurement System). Os espinélios normais CuCr2O4 e MnCr2O4 são ferrimagnéticos com temperatura de Curie de 122 K e 43 K, respectivamente. A cromita de zinco (ZnCr2O4) que na sua forma nanométrica apresenta um ordenamento antiferromagnético com temperatura de Néel (TN) de 5 K, e o NiCr2O4 mostra duas transições magnéticas, uma em TC 75K relacionada a uma componente ferrimagnética (longitudinal) e a segunda a TS 30K, associada a componente antiferromagnética (transversal). A magnetização no sistema Mn1-xZnxCr2O4 para 0 x 0:5 indica características de um ordenamento antiferromagnético (AF), enquanto valores de x 0:6 definem o sistema com um ordenamento tipicamente ferrimagnético (FI). O interessante comportamento nas fronteiras da fase AF/FI é caracterizado pelo aparecimento de campo coercivo nos ciclos de histerese e duas temperaturas de ordem magnética. No entanto, para a outra série de cromitas espinélias Cu1-xNixCr2O4, com x 0:5, os compostos são ferrimagnéticos. No intervalo de 0:5 x 1:0 surgem duas transições magnéticas com um aumento do campo coercivo que pode ser associado com o surgimento de componentes (FI) e (AF). Os ciclos de histereses das amostras são claramente assimétricos, e este comportamento pode ser atribuído a efeitos de exchange bias originários da presença de uma fase antiferromagnética e ferrimagnética nas amostras. No presente trabalho mostramos os resultados das propriedades magnéticas das cromitas espinélias Mn1-xZnzCr2O4 e Cu1-xNixCr2O4 (0 x 1; 0) em escala nanométrica e bulk. O Efeito Magnetocalórico (EMC) foi investigado em três amostras do tipo espinélios, os dados foram obtidos das medidas de magnetização em função da temperatura e verificou-se a variação da entropia de cada uma delas, observamos a variação da temperatura de transição magnética com o campo magnético aplicado, porém não observamos grandes valores de intensidade do EMC.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPESapplication/pdfporUniversidade Federal de SergipePós-Graduação em FísicaUFSBrasilFísicaCromitaNanopartículasMagnetismoCaracterização magnéticaCoprecipitaçãoCIENCIAS EXATAS E DA TERRA::FISICACaracterização estrutural e magnética de cromitas produzidas pelo método de coprecipitaçãoinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/doctoralThesisinfo:eu-repo/semantics/openAccessreponame:Repositório Institucional da UFSinstname:Universidade Federal de Sergipe (UFS)instacron:UFSORIGINALTHIAGO_TARGINO_GURGEL.pdfapplication/pdf26345377https://ri.ufs.br/jspui/bitstream/riufs/5259/1/THIAGO_TARGINO_GURGEL.pdf83dbdb351d3052359d4df66b8388874cMD51TEXTTHIAGO_TARGINO_GURGEL.pdf.txtTHIAGO_TARGINO_GURGEL.pdf.txtExtracted texttext/plain189536https://ri.ufs.br/jspui/bitstream/riufs/5259/2/THIAGO_TARGINO_GURGEL.pdf.txt58bd12ff3c9247a45f0597eb3af4ee5bMD52THUMBNAILTHIAGO_TARGINO_GURGEL.pdf.jpgTHIAGO_TARGINO_GURGEL.pdf.jpgGenerated Thumbnailimage/jpeg1601https://ri.ufs.br/jspui/bitstream/riufs/5259/3/THIAGO_TARGINO_GURGEL.pdf.jpg71c49c56e88d8c8d51a689ce6d7b5c91MD53riufs/52592018-06-12 18:02:24.709oai:ufs.br:riufs/5259Repositório InstitucionalPUBhttps://ri.ufs.br/oai/requestrepositorio@academico.ufs.bropendoar:2018-06-12T21:02:24Repositório Institucional da UFS - Universidade Federal de Sergipe (UFS)false |
dc.title.por.fl_str_mv |
Caracterização estrutural e magnética de cromitas produzidas pelo método de coprecipitação |
title |
Caracterização estrutural e magnética de cromitas produzidas pelo método de coprecipitação |
spellingShingle |
Caracterização estrutural e magnética de cromitas produzidas pelo método de coprecipitação Gurgel, Thiago Targino Física Cromita Nanopartículas Magnetismo Caracterização magnética Coprecipitação CIENCIAS EXATAS E DA TERRA::FISICA |
title_short |
Caracterização estrutural e magnética de cromitas produzidas pelo método de coprecipitação |
title_full |
Caracterização estrutural e magnética de cromitas produzidas pelo método de coprecipitação |
title_fullStr |
Caracterização estrutural e magnética de cromitas produzidas pelo método de coprecipitação |
title_full_unstemmed |
Caracterização estrutural e magnética de cromitas produzidas pelo método de coprecipitação |
title_sort |
Caracterização estrutural e magnética de cromitas produzidas pelo método de coprecipitação |
author |
Gurgel, Thiago Targino |
author_facet |
Gurgel, Thiago Targino |
author_role |
author |
dc.contributor.author.fl_str_mv |
Gurgel, Thiago Targino |
dc.contributor.advisor1.fl_str_mv |
Salazar, Nelson Orlando Moreno |
dc.contributor.authorLattes.fl_str_mv |
http://lattes.cnpq.br/5139755580254522 |
contributor_str_mv |
Salazar, Nelson Orlando Moreno |
dc.subject.por.fl_str_mv |
Física Cromita Nanopartículas Magnetismo Caracterização magnética Coprecipitação |
topic |
Física Cromita Nanopartículas Magnetismo Caracterização magnética Coprecipitação CIENCIAS EXATAS E DA TERRA::FISICA |
dc.subject.cnpq.fl_str_mv |
CIENCIAS EXATAS E DA TERRA::FISICA |
description |
Polycrystalline samples Mn1-xZnzCr2O4 and Cu1-xNixCr2O4 (0 x 1; 0) were produced by co-precipitation method and treated at temperatures of 400oC and 1200oC. The samples have been investigated by dc/ac magnetization as a function of temperature and magnetic field. In addition, Xray powder diffraction, X-ray fluorescence and scanning electron microscopy measurements were carried out at room temperature. The analysis results of X-ray diffraction showed that the materials are single phase. The structural refinement was carried out by the Rietveld method and cell parameters determined for these materials are consistent with those reported in the literature for bulk samples. The average particle sizes were calculated using the equation of Scherrer and compared to the sizes obtained by scanning electron microscopy. It is observed that these spinel particles have an average size of 18-55 nm. It is noted an increase in the average size with increasing calcination temperature. We study the evolution of the magnetic properties of normal spinels of the series Mn1-xZnzCr2O4 and Cu1-xNixCr2O4 through magnetic measurements with magnetometer PPMS-9T (Physical Property measurement system). Normal spinels CuCr2O4 and MnCr2O4 are ferromagnetic with Curie temperature 122 K and 43 K respectively. The zinc chromite (ZnCr2O4) which in its nano-form features an antiferromagnetic ordering with Néel temperature (TN) of 5 K, the NiCr2O4 shows two magnetic transitions, one at TC 75K related to a ferromagnetic component (longitudinal) and the second the TS 30K, associada a componente antiferromagnética (transversal). The magnetization in the system Mn1-xZnxCr2O4 for 0 x 0:5 indicates characteristics of an antiferromagnetic ordering (AF), while values of x 0:6 define the system with a typical ferrimagnetic order (FI). The behavior at the borders of AF / FI phase is indicated by the appearance of coercive field in hysteresis loops and two temperatures magnetic order. However, for other series of chromite spinel Cu1-xNixCr2O4, with x 0:5, the compounds are ferrimagnetic. In the range of 0:5 x 1:0 arise two magnetic transitions with an increased coercive field which may be associated with the emergence of components (FI) and (AF). The hysteresis cycles of the samples are clearly asymmetric, and this behavior can be attributed to the originating exchange bias effect of the presence of a ferrimagnetic and antiferromagnetic layer in the samples. In the present study we show the results of the magnetic properties of spinel chromite Mn1-xZnzCr2O4 and Cu1-xNixCr2O4 (0 x 1; 0) on a nanometric scale and bulk.EMC was investigated in three spinel type samples, when data are obtained by the measurement magnetization as function of temperature and found the change of entropy of each of them, we observe the change in the magnetic transition temperature with the applied magnetic field, but we noted not large EMC intensity values. |
publishDate |
2016 |
dc.date.issued.fl_str_mv |
2016-07-26 |
dc.date.accessioned.fl_str_mv |
2017-09-26T18:23:54Z |
dc.date.available.fl_str_mv |
2017-09-26T18:23:54Z |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/doctoralThesis |
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doctoralThesis |
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publishedVersion |
dc.identifier.citation.fl_str_mv |
GURGEL, Thiago Targino. Caracterização estrutural e magnética de cromitas produzidas pelo método de coprecipitação. 2016. 122 f. Tese (Pós-Graduação em Física) - Universidade Federal de Sergipe, São Cristóvão, SE, 2016. |
dc.identifier.uri.fl_str_mv |
https://ri.ufs.br/handle/riufs/5259 |
identifier_str_mv |
GURGEL, Thiago Targino. Caracterização estrutural e magnética de cromitas produzidas pelo método de coprecipitação. 2016. 122 f. Tese (Pós-Graduação em Física) - Universidade Federal de Sergipe, São Cristóvão, SE, 2016. |
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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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Universidade Federal de Sergipe |
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