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MA: Fachverband Magnetismus

MA 22: Caloric Effects in Ferromagnetic Materials

MA 22.8: Vortrag

Mittwoch, 19. März 2025, 11:15–11:30, H19

Towards the hydrogenation of DyCo2 for cryogenic magnetocaloric liquefaction applications — •Allan Döring, Imants Dirba, Fernando Maccari, Konstantin Skokov, and Oliver Gutfleisch — TU Darmstadt, Darmstadt, Germany

Hydrogen can play an important role in the carbon-neutral society. Liquid H2 stands out for its higher volume-to-energy ratio. However, the current liquefaction method sums up to 34% of the costs to liquefy H. The magnetocaloric cooling could be one alternative to improve the efficiency of this process. Hence, research for materials with intense magnetocaloric effect (MCE) between 20 K and 77 K is needed. Those materials exhibit the peak of the MCE at transition temperatures, such as the Curie temperature (TC). Further, the MCE is stronger in heavy rare-earth (Re) based compounds, such as ReCo2. However, some of the ReCo2 materials exhibit giant MCE in temperatures above 77 K, and one way to shift down TC of such compounds is by introducing H as interstitial atoms. The TC of DyCo2 was shifted down by 120 K through the hydrogenation processK. Further, partially hydrogenated samples showed two distinct TCs. By X-ray diffraction analysis a crystalline state was confirmed with distorted lattices. The magnetic entropy changes were measured in non-hydrogenates, partially and fully hydrogenated samples, revealing a peak of entropy change at 25 K after hydrogenation. The reversibility of hydrogenation and its microstrutuctre was also investigated. We acknowledge the HyLICAL project through grant 101101461.

Keywords: Magnetocaloric; Cryogenic; Cooling