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Magnetic

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Near Room Temperature Magnetocaloric Materials For Magnetic Refrigeration, Eduardo Martinez Teran Jan 2019

Near Room Temperature Magnetocaloric Materials For Magnetic Refrigeration, Eduardo Martinez Teran

Open Access Theses & Dissertations

Magnetic refrigeration (MR) is a cooling process based on the magnetocaloric effect (MCE) that is present to some extent in all magnetic materials, and the ones in which this effect is more appreciable are called magnetocaloric materials (MCM). The implementation of new designs and materials for the construction of cooling systems is a must do, being essential that these improved designs will reduce the environmental impact and increase the efficiency of their predecessors. In this thesis, the magnetocaloric effect theory is presented from a thermodynamic point of view and also the synthesis and study to a new Heusler alloy (MnFe2Ga ...


Magnetic And Structural Properties Of Zinc-Doped Nickel Ferrite, Kanokporn Chattrakun Jan 2011

Magnetic And Structural Properties Of Zinc-Doped Nickel Ferrite, Kanokporn Chattrakun

Open Access Theses & Dissertations

We have used dc-magnetization, ac-magnetic susceptibility and x-ray diffraction (XRD) to investigate the microscopic origin of the magnetic property modifications induced by zinc doping in bulk and nano-sized nickel ferrite. Magnetic measurements indicate that the nanoparticle energy barrier to magnetization reversal, EB, and the bulk saturation magnetization, Ms, follow similar dependences on the zinc doping fraction, x. Both these magnetic quantities initially increase with increasing x, reach a maximum at x~0.5, and eventually decrease upon further doping. Synchrotron and laboratory powder XRD data show no evidence of significant structural modifications for x~0.5: we find ...