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A setup for direct measurement of the adiabatic temperature change in magnetocaloric materials
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.ORCID iD: 0000-0003-2790-116x
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.ORCID iD: 0000-0003-3574-2146
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.ORCID iD: 0000-0001-5435-2958
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.ORCID iD: 0000-0002-3049-6831
2023 (English)In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 72, p. 1-9Article in journal (Refereed) Published
Abstract [en]

In order to find a highly efficient, environmentally-friendly magnetic refrigerant, direct measurements of the adiabatic temperature change ΔTadb are required. Here, in this work, a simple setup for the ΔTadb measurement is presented. Using a permanent magnet Halbach array with a maximum magnetic field of 1.8 T and a rate of magnetic field change of 5 T/s, accurate determination of ΔTadb is possible in this system. The operating temperature range of the system is from 100 to 400 K, designed for the characterization of materials with potential for room temperature magnetic refrigeration applications. Using the setup, ΔTadb of a first-order and two second-order compounds have been studied. Results from the direct measurement for the first-order compound have been compared with ΔTadb calculated from the temperature and magnetic field-dependent specific heat data. By comparing results from direct and indirect measurements, it is concluded that for a reliable characterization of the magnetocaloric effect (MCE), direct measurement of ΔTadb should be adopted.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2023. Vol. 72, p. 1-9
National Category
Condensed Matter Physics
Identifiers
URN: urn:nbn:se:uu:diva-487263DOI: 10.1109/TIM.2023.3272387ISI: 000991806800037OAI: oai:DiVA.org:uu-487263DiVA, id: diva2:1706604
Funder
Swedish Foundation for Strategic Research, EM−16−0039Available from: 2022-10-26 Created: 2022-10-26 Last updated: 2023-08-14Bibliographically approved
In thesis
1. Direct and indirect magnetocaloric properties of first- and second-order phase transition materials
Open this publication in new window or tab >>Direct and indirect magnetocaloric properties of first- and second-order phase transition materials
2022 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The energy-efficient and environmentally friendly alternative cooling technology based on the magnetocaloric effect (MCE) is discussed in this thesis. The thesis has two major parts, one devoted to material characterization and the other to instrument development. Different magnetic oxides and intermetallic compounds with second-order and first-order magnetic transitions, respectively, were studied with the aim of finding materials suitable for magnetic refrigeration. For the application of the MCE, a high value of the isothermal entropy changes and the relative cooling power (RCP), along with minimal temperature hysteresis are required. The temperature hysteresis is negligible for all studied second-order compounds, while an almost ten times higher value of the isothermal entropy change has been observed for the first-order compounds. The highest value of isothermal entropy change (20 J/kgK at 2 T applied magnetic field) has been observed for the MnNiSi-type compounds exhibiting magneto-structural phase transitions, while the largest value of the RCP (176 J/kg at 2 T applied magnetic field) has been observed for the Fe2P-type compounds exhibiting magneto-elastic phase transitions.

For the characterization of magnetocaloric properties, one important parameter is the adiabatic temperature change, which is often not reported in literature owing to the lack of experimental setups for direct measurements of the magnetocaloric effect. This thesis also includes the development of a setup for the direct measurement of the adiabatic temperature change upon a change in a magnetic field.  

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2022. p. 63
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 2212
Keywords
Magnetocaloric effect, Adiabatic temperature change, Direct measurement of magnetocaloric effect, Griffiths phase, Magneto-elastic transition, Magneto-structural transition, Second-order magnetic phase transition, First-order magnetic phase transition, Isothermal magnetic entropy change
National Category
Natural Sciences
Research subject
Physics
Identifiers
urn:nbn:se:uu:diva-487266 (URN)978-91-513-1644-4 (ISBN)
Public defence
2022-12-14, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala , 75237 Sweden, Uppsala, 09:00 (English)
Opponent
Supervisors
Available from: 2022-11-22 Created: 2022-10-27 Last updated: 2022-11-22

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Ghorai, SagarHedlund, DanielKapuscinski, MartinSvedlindh, Peter

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