NIMS:the highest performance magnetic refrigeration material: High efficiency of hydrogen liquefaction
-Advancing to high efficiency of hydrogen liquefaction, which is essential for realizing hydrogen society-
NIMS:
Using machine learning, we discovered the world’s highest performance magnetic refrigeration material for hydrogen liquefaction.
This is expected to reduce the cost of producing liquefied hydrogen, which has been a major obstacle to the realization of a hydrogen society.
https://www.jst.go.jp/pr/announce/20200512/pdf/20200512.pdf
Machine-learning-guided discovery of the gigantic magnetocaloric effect in HoB2 near the hydrogen liquefaction temperature
Pedro Baptista de Castro, Kensei Terashima, […]Yoshihiko Takano
Published: 12 May 2020
NPG Asia Materials volume 12,
Article number: 35 (2020) Cite this article
Abstract
Magnetic refrigeration exploits the magnetocaloric effect,
which is the entropy change upon the application and removal of magnetic fields in materials, providing an alternate path for refrigeration other than conventional gas cycles.
While intensive research
has uncovered a vast number of magnetic materials that exhibit a large magnetocaloric effect, these properties remain unknown for a substantial number of compounds.
To explore new functional materials in this unknown space, machine learning is used as a guide for selecting materials
that could exhibit a large magnetocaloric effect.
By this approach,
- HoB2 is singled out and synthesized, and
- its magnetocaloric properties are evaluated,
leading to the experimental discovery of a gigantic magnetic entropy change of 40.1 J kg−1 K−1 (0.35 J cm−3 K−1) for a field change of 5 T in the vicinity of a ferromagnetic second-order phase transition with a Curie temperature of 15 K.
This is the highest value reported so far,
to the best of our knowledge, near the hydrogen liquefaction temperature;
thus, HoB2 is a highly suitable material for hydrogen liquefaction and low-temperature magnetic cooling applications.
https://www.nature.com/articles/s41427-020-0214-y