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Investigating Itinerant Magnets for Magnetic Refrigeration

Title: Investigating Itinerant Magnets for Magnetic Refrigeration.
Name(s): Ventrella, Elizabeth, author
Type of Resource: text
Genre: text
bachelor thesis
Date Issued: 2017-04-28
Physical Form: computer
Physical Form: online resource
Extent: 1 online resource
Language(s): English
Abstract/Description: Clean and efficient energy-conversion systems for large-scale and residential use could reduce the detrimental impacts of fossil fuel consumption on the environment. Magnetocaloric materials hold the potential to move refrigerators from conventional vapor-compression cycles to energy-efficient and environmentally-friendly magnet-based refrigeration technology. The latter takes advantage of the magnetocaloric effect (MCE), a reversible temperature change of a material upon the application or removal of an external magnetic field. The major goal of this research is to discover materials that exhibit large MCE and contain nontoxic and abundant elements. The search for these materials is being guided by both computational efforts and extensive analysis of existing materials and modifications that can improve their properties. In this contribution, I report my investigation of CuFe2Ge2, Cu0.6Mn2.4Ge2, and LiFe6Ge6 as potential itinerant magnets and magnetocaloric materials. Synthesized samples were analyzed by electronic structure calculations, powder X-ray diffraction, and magnetic measurements. Preliminary findings revealed that LiFe6Ge6 does not show ferromagnetic behavior and thus cannot be used in magnetic refrigeration. The reasons for the lack of magnetic ordering are still to be determined. The Cu-Fe-Mn-Ge system revealed the formation of phases with structures related to Cu0.6Mn2.4Ge2 and CuFe2Ge2 for compositions close to these terminal members of the series. At the 1:1 Mn/Fe ratio, however, a new material has been produced that exhibits a superstructure of previously reported Cu1.6Mn20Ge10.4. The magnetic properties of these materials need further investigation.
Identifier: FSU_libsubv1_scholarship_submission_1493404076 (IID)
Keywords: Itinerant Magnetism, Magnetism, Ferromagnetism, Magnetic refrigeration, Magnetocaloric effect
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Owner Institution: FSU