Magnetic refrigeration material operating at a full temperature range required for hydrogen liquefaction

Application of magnetic refrigeration (MR) for hydrogen liquefaction is limited by lack of MR materials with a large magnetocaloric effect (MCE). Here the authors show a series of MR materials with a large and reversible MCE operating at a full temperature range required for hydrogen liquefaction. Magnetic refrigeration (MR) is a key technique for hydrogen liquefaction. Although the MR has ideally higher performance than the conventional gas compression technique around the hydrogen liquefaction temperature, the lack of MR materials with high magnetic entropy change in a wide temperature range required for the hydrogen liquefaction is a bottle-neck for practical applications of MR cooling systems. Here, we show a series of materials with a giant magnetocaloric effect (MCE) in magnetic entropy change (- increment S-m > 0.2 J cm(-3)K(-1)) in the Er(Ho)Co-2-based compounds, suitable for operation in the full temperature range required for hydrogen liquefaction (20-77 K). We also demonstrate that the giant MCE becomes reversible, enabling sustainable use of the MR materials, by eliminating the magneto-structural phase transition that leads to deterioration of the MCE. This discovery can lead to the application of Er(Ho)Co-2-based alloys for the hydrogen liquefaction using MR cooling technology for the future green fuel society.

Automated summary

The authors demonstrate a series of materials with a large and reversible magnetocaloric effect, suitable for the full temperature range required for hydrogen liquefaction. By eliminating the magneto-structural phase transition, the giant magnetocaloric effect becomes reversible.