Large cryogenic magnetocaloric effect of the Laves-phase Ho_1-xDy_xAl₂ compounds within liquid hydrogen temperature range

In this work, a large cryogenic magnetocaloric effect was achieved in laves-phase Ho_1-xDy_xAl₂ (x = 0, 0.25, 0.5, 0.75, 1) compounds with MgCu₂-type cubic structure (space groupFd3̅m). The Ho_1-xDy_xAl₂ compounds undergo the second order magnetic transition. The maximum magnetic entropy changes with the μ₀∆H = 5 T of the Ho_1-xDy_xAl₂ bulks are 27.5, 25.2, 22.2, 20.8, and 19.8 J kg⁻¹ K⁻¹ respectively. The spherical particles of Ho_1-xDy_xAl₂ were prepared by electrode induction melting gas atomization (EIGA). The gas-atomized particles exhibit high sphericity. Additionally, the Curie temperature and the order of magnetic phase transition of the spherical particles are consistent with those of bulk counterparts. The maximum magnetic entropy with μ₀∆H = 5 T of Ho_0.5Dy_0.5Al₂ spherical particles reaches 17.20 J kg⁻¹ K⁻¹. The excellent magnetocaloric properties of the bulks and spherical particles facilitate the production of magnetic refrigerants needed for developing magnetic refrigerators operating within the liquid hydrogen temperature range.