Design of hydrogen-liquefied magnetic refrigeration materials by elemental regulation in RE_3–xHo_xB_0.5C_3.5 (RE=Dy, Tb) compounds

The search for high-abundance compounds containing rare earth elements to develop high-performance magnetic refrigeration materials for hydrogen liquefaction has become a particularly attractive research direction. We successfully manipulated the magnetic interactions in tetragonal rare earth carbides (RE₃C₄) by doping them with boron (B) element, transforming their state from antiferromagnetic to ferromagnetic. Theoretical calculations and experimental results indicate that the transition in magnetic interactions may be due to the synergistic effects of electronic structure and lattice distortions. Building on this, further doping with holmium (Ho) element was used to adjust the magnetic transition temperature of the system. The results show that the magnetic transition temperature of this series of compounds can be effectively altered within the range of 26–42.8 K. By optimizing the composition of rare earth elements, a series of novel candidate materials exhibiting significant magnetocaloric effects within the temperature range required for hydrogen liquefaction is successfully developed.