Berlin 2018 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 20: Magnetocaloric effects (joint session MA/TT)
MA 20.4: Vortrag
Dienstag, 13. März 2018, 10:15–10:30, EB 407
Dynamic effects of the magneto-elastic phase transition in a Fe2P-type magnetocaloric alloy — •Maximilian Fries1, Pfeuffer Lukas1, Tino Gottschall1,2, Franziska Scheibel1,3, Konstantin Skokov1, Youri Skourski2, Mehmet Acet3, Michael Farle3, Jochen Wosnitza3, and Oliver Gutfleisch1 — 1Institut für Materialwissenschaft, Technische Universität Darmstadt, 64287 Darmstadt — 2Hochfeldlabor Dresden (HLD-EMFL), Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden — 3Fakultät für Physik und CENIDE, Universität Duisburg-Essen, 47057 Duisburg
Magnetic refrigeration could be an efficient alternative refrigeration technology if operated at high cycling frequencies [1]. In order to investigate if the magnetocaloric materials are applicable in a high-frequency cooling device we measured the adiabatic temperature change Δ Tad of a Fe2P-type alloy [2] under different field-change rates ranging from 0.93 Ts−1 in a permanent-magnet-based Halbach setup to 2700 Ts−1 in pulsed fields. We observed that a field-rate independent second-order like phase transition always overlaps with the first-order phase transition leading to a non-saturating behavior of Δ Tad even in fields up to 20 T. By measurements under different field pulse rates we show that the first-order phase transition cannot follow the fast field changes, resulting in a distinct field-dependent hysteresis of Δ Tad.
[1] O. Gutfleisch et al., Philosophical Transactions of the Royal Society A 374 (2016) 20150308. [2] M. Fries et al., Acta Materialia 132 (2017) 222