Influência da substituição de Mn por Fe sobre o efeito magnetocalórico inverso de ligas Heusler tipo Ni-Mn-Sn
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Data
2008-05-30
Autores
Xavier, Fábio
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Universidade Federal do Espírito Santo
Resumo
In this work, the magnetic entropy change was observedexperimentally inthe Heusler alloys Ni2(Mn1-xFex)Sn with x = (0; 0,25; 0,33; 0,50; 0,75)(series A)and type Ni2(Mn1-xFex)1,44Sn0,56with x = (0; 0,03; 0,07; 0,10; 0,15)(series B).The structural characterization of these alloys was carried by measurements ofX-Raydiffraction andElectronic Microscopy.The magnetocaloric properties had been quantified by magnetizationmeasurements in function of the temperature and applied magnetic field. The X-Ray diffraction patterns evidences a cubic phase type L21 for all samples at room temperature. The magnetization measurement for samples of series A,exhibitedaferromagnetic behavior.However, the increase of Fe concentrations in these samples resulted in a decrease of the Curietemperature (Tc) from 330 K to 290 K. The magnetization measurement for samples of series B, had demonstrated the presence of a structural phase transition until contents of 7% ofFe. The increase of iron content in these samples has resulted in an increase of the TCof 302 to 325 K and a reduction in the structural phase transition temperature of 290 to 160 K. Theinverse magnetocaloric effect was observed in samples of series Bwith structural transitionof type martensitic-austenitic. The magneticentropy change observed next to the structural transition temperatureswas of 10 J/kg.Kapproximately, inan applied magnetic field of 5 T.
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Magnetic Materials , Refrigeration , Magnetocaloric effect , Materiais magnéticos , Refrigeração , Efeito magnetocalórico
Citação
XAVIER, Fábio. Influência da substituição de Mn por Fe sobre o efeito magnetocalórico inverso de ligas Heusler tipo Ni-Mn-Sn. 2008. 91 f. Dissertação (Mestrado em Física) – Programa de Pós-Graduação em Física, Universidade Federal do Espírito Santo, Centro de Ciências Exatas e da Terra, Vitória, 2008.