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MA: Fachverband Magnetismus

MA 29: Caloric Effects in Magnetic Materials

MA 29.1: Vortrag

Donnerstag, 8. September 2022, 09:30–09:45, H47

"Giant" magnetocaloric effects for 2nd order phase transition near 20 K: a study on rare-earth Laves phases for hydrogen liquefaction — •Wei Liu¹, Franziska Scheibel¹, Tino Gottschall², Eduard Bykov², Konstantin Skokov¹, and Oliver Gutfleisch¹ — ¹Funktionale Materialien, Technische Universität, TU Darmstadt, Germany — ²Hochfeld- Magnetlabor Dresden, Helmholtz-Zentrum Dresden-Rossendorf, Germany

Hydrogen will play a key role for building a climate-neutral society, where renewables are the major energy sources [1]. Liquid hydrogen is essential for efficient storage and transport of hydrogen, but expensive due to the low efficiency of traditional gas-compression refrigeration [2]. As an emerging and energy-saving technology, magnetocaloric gas liquefaction can be an a "game-changer". Here we report a noticeable, but unaddressed feature for magnetocaloric hydrogen liquefaction using rare-earth-based intermetallic alloys: magnetocaloric effect of a 2nd order magnetocaloric materials can become "giant" when the Curie temperature TC is near the hydrogen boiling point of 20 K. Based on our study on rare-earth Laves phases for hydrogen liquefaction and a comprehensive literature review, we summarized two phenomenological rules for a rare-earth-based intermetallic series: (1) magnetic entropy change increases with decreasing TC; (2) adiabatic temperature change decreases firstly with decreasing TC but increases in cryogenic temperature range. These findings are well interpreted by a mean-field approach. Our studies can guide the materials design for hydrogen liquefaction.