Giant low-field magnetocaloric effect in hexagonal Eu₃B₂O₆ compound

A modified solid-phase reaction method was used to synthesize the polycrystalline Eu₃B₂O₆-as a novel cryogenic magnetocaloric material. In addition, investigations into the magnetocaloric effect (MCE), magnetic properties and crystal structure of compound have been precisely completed. The results indicate that the compound undergoes a second-order magnetic-phase transition from ferromagnetic to paramagnetic at 8 K and has a hexagonal structure that belongs to the R-3c space group. Meanwhile, the MCE was evaluated by using magnetic entropy change (-ΔS_M), temperature averaged entropy change (TEC) as well as the refrigeration capacity (RC) for Eu₃B₂O₆. Under the field change from 0 to 5 T, the maximal values of -ΔS_M and TEC (5) are 38.6 and 35.7 J kg⁻¹ K⁻¹, respectively, while the corresponding RC reaches 435.9 J kg⁻¹. The giant low-field MCE facilitates device miniaturization and cost reduction, making Eu₃B₂O₆ compound a promising candidate for cryogenic magnetic refrigeration.