Exploration of the rare-earth cobalt nickel-based magnetocaloric materials for hydrogen liquefaction

摘要

Magnetic refrigeration based on the magnetocaloric effect(MCE)of magnetic solids has been considered as an emerging technology for hydrogen liquefaction.However,the lack of high-performance materials has slowed the development of any practical applications.Here,we present a family of rare-earth cobalt nickel-based magnetocaloric materials,namely Dy_(1-x)Ho_(x)CoNi and Ho_(1-x)Er_(x)CoNi compounds,and system-atically investigated their structural and magnetic properties as well as the MCE and magnetocaloric per-formance.All of these compounds crystallize in the C15-type Laves-phase structure and undergo typi-cal second-order magnetic phase transition(MPT).The change in magnetism and the MPT temperature for the Dy_(1-x)Ho_(x)CoNi and Ho_(1-x)Er_(x)CoNi compounds originate from the exchange interactions between nearest-neighbor RE 3+ion pairs.No hysteresis magnetocaloric effect was achieved,and the MPT tem-perature of these compounds could be tuned from the liquefaction temperature of nitrogen(∼77 K)to hydrogen(∼20 K)by adjusting the ratio of rare-earth elements.This study’s findings indicate that theDy_(1-x)Ho_(x)CoNi and Ho_(1-x)Er_(x)CoNi compounds are of potential for practical magnetic refrigeration applica-tions in the field of hydrogen liquefaction.