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MA: Fachverband Magnetismus

MA 51: Caloric Effects in Ferromagnetic Materials

MA 51.11: Talk

Friday, March 22, 2024, 12:30–12:45, H 2013

Highly reversible magnetocaloric effect in Gd₅Si_0.25Ge_3.75 in moderate magnetic fields for hydrogen liquefaction — •Wei Liu¹, Eduard Bykov², Tino Gottschall², Konstantin Skokov¹, and Oliver Gutfleisch¹ — ¹Materials Science, Technical University of Darmstadt, Darmstadt, Germany — ²High Magnetic Field Lab, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany

Magnetocaloric (MC) hydrogen liquefaction could be a ’game changer’ for the liquid hydrogen industry due to its potentially higher efficiency than the conventional Joule-Thomson-expansion-based liquefaction technologies [1]. However, second-order MC materials exhibit less excellent MCEs near the nitrogen condensation point (77 K), where the hydrogen starts to be cooled by a magnetic cooling cycle to reach its condensation point (20 K) [2]. First-order MC materials can achieve much higher MCEs, but their poor reversibility due to their significant thermal hysteresis is a problem which makes their applications in real devices more complex [3]. In this work, we demonstrate that Gd₅Si_0.25Ge_3.75 exhibits a highly reversible MCE near 77 K in a magnetic field of 5 T despite its significant thermal hysteresis. Considering that a magnetic field of 5 T is often proposed to be used in a practical active magnetic regenerator, this work shows that first-order MC materials with significant thermal hysteresis can also be promising candidates for hydrogen liquefaction.

[1] Liu et al., J. Phys. Energy 3 (2023), 034001 [2] Liu et al., Appl. Mater. Today 29 (2022), 101624 [3] Gutfleisch et al., Phil. Trans. R. Soc. A 374 (2016), 20150308

Keywords: Magnetism; Magnetic Materials; Magnetocaloric; Phase transition; Hydrogen liquefaction