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 (-ΔSM), 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 -ΔSM 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. [Display omitted] •A novel cryogenic MCE material (Eu3B2O6 compound) was synthesized.•Giant low field MCE was obtained in Eu3B2O6 compound.•Giant MCE could be triggered by field change as low as 0–1 T.•Eu3B2O6 compounds are promising cryogenic MCE material near TC of 8 K.