Wide temperature span and giant refrigeration capacity magnetic refrigeration materials for hydrogen liquefaction.

This article systematically investigates the crystal structure, electronic structure, magnetism, and magnetocaloric effect (MCE) of the Ho₅B₂C₅ compound, focusing on its potential for magnetic refrigeration in hydrogen liquefaction. The compound crystallizes in a tetragonal structure (space group P4/ncc) and exhibits a ferromagnetic ground state with a second-order magnetic phase transition to a paramagnetic state around 27 K. Under magnetic field changes from 0 to 7 T, Ho₅B₂C₅ demonstrates a large magnetic entropy change (−ΔS_M^max = 21.3 J/kg·K), high refrigeration capacity (RC = 1001.6 J/kg), and a wide effective temperature range (~60 K), making it a promising candidate for efficient, wide-range magnetic refrigeration technology. The study combines theoretical density functional theory calculations and experimental measurements, confirming the material's metallic nature and favorable magnetic properties compared to other rare-earth-based refrigerants.