# Fileset

[Thermag-2024 (1).docx](https://mdr.nims.go.jp/filesets/9baa6f27-289f-4a06-b564-fa9bcb16fb78/download)

## Creator

[TANG Xin](https://orcid.org/0000-0001-6762-6145), WANG Zexuan, [BOLYACHKIN Anton](https://orcid.org/0000-0003-0420-1806), [SEPEHRI AMIN Hossein](https://orcid.org/0000-0002-7856-7897), [OHKUBO Tadakatsu](https://orcid.org/0000-0003-3548-1951), [HONO Kazuhiro](https://orcid.org/0000-0001-7367-0193)

## Rights

[Creative Commons BY-NC Attribution-NonCommercial 4.0 International](https://creativecommons.org/licenses/by-nc/4.0/)

## Other metadata

[Magnetocaloric materials for cryogenic application](https://mdr.nims.go.jp/datasets/fb6665bc-8fb7-47cf-9116-7d448f50c10e)

## Fulltext

Magnetocaloric materials for cryogenic applicationXin Tang, Z. Wang, A. Bolyachkin, H. Sepehri-Amin, T. Ohkubo, K. HonoNational Institute for Materials Science, Tsukuba 305-0047, Japan Hydrogen is a carbon-free energy carrier that is expected to play an important role in achieving carbon neutrality in future society. However, hydrogen gas has a large volume and its liquefaction is necessary for its storage and transportation. Liquefaction of hydrogen is currently realized by the conventional gas compression method (Joule-Thompson method), which is costly with low efficiency. To overcome these problems, a novel gas liquefaction approach needs to be developed. Magnetic refrigeration (MR) based on the magnetocaloric effect (MCE) ideally has higher performance than the conventional gas compression technique at cryogenic temperatures. However, the lack of MR materials with large magnetic entropy change in a wide temperature range required for the hydrogen liquefaction is a bottleneck for practical applications of MR cooling systems as shown in Figure 1 (a-b). In this talk, we first explore the potential of La(Fe,Si)13-based and (Mn,Fe)2(P,Si)-based compounds for cryogenic applications [1-2]. In the second part, we demonstrate the development of a series of Er(Ho)Co2-based refrigerants with a giant magnetocaloric effect in magnetic entropy change (-∆Sm > 0.2 J cm-3K-1) that fully covers the practical application temperature window (20-77 K) required for hydrogen liquefaction (Fig. 1c). The magnetic refrigerants developed in this study yielded significantly larger entropy changes than conventional ones, implying that the materials developed in this work could boost the efficiency of hydrogen liquefaction in practical applications [3]. In addition, giant MCE becomes reversible by elimination of hysteresis, enabling sustainable use of the developed MR materials. In the final section of my talk, we achieved a well-balanced MCE in Fe2P-type compound through extrinsic control of hysteresis for room temperature refrigeration application.Figure 1. Development of high-performance magnetic refrigerant materials for hydrogen liquefaction. (a) Schematics of active magnetic regenerator; (b) requirement of materials for practical application; (c) giant and reversible magnetocaloric effect of materials [1] J. Lai et al. Acta Mater. 232 (2022) 117942.[2] J. Lai et al. Acta Mater. 220 (2021) 117286.[3] X. Tang et al. Nature Communications 13 (2022) 1817.image1.emfMaterials developed in this workHoB2HoAl2HoAl2(c)(Ho)ErCo2-based alloys(b)(a)Temp. (K)