Review on the materials and devices for magnetic refrigeration in the temperature range of nitrogen and hydrogen liquefaction

Magnetic refrigeration based on magnetocaloric effect (MCE) has become a promising alternative technique to the traditional gas-compression refrigeration due to its friendly environment and high energy efficiency. In addition to room temperature magnetic refrigeration, this novel technology can be applied at low temperature, especially for the potential applications in gas liquefaction. Therefore, attention has been paid to explore suitable materials with large MCE near the gas liquefaction temperature and develop low temperature magnetic refrigerators. Herein, the typical magnetocaloric materials and prototypes in the temperature range of nitrogen and hydrogen liquefaction are reviewed. Heavy rare earth intermetallic compounds are promising for low temperature magnetic refrigeration due to a low ordering temperature and large magnetic moments. For example, DyFeSi compound shows a large reversible MCE under a low field change of 1 T around T-C = 70 K, which is near the liquefaction temperature of nitrogen (77 K). It has been proposed that a composite can be formed by a group of magnetic refrigeration materials with successive transition temperatures and nearly constant MCEs, therefore expanding the range of working temperature desirable for Ericsson-cycle magnetic refrigeration.