Giant Low-Field Magnetocaloric Effect in Hexagonal Eu3b2o6 Compound

Abstract

A modified solid-phase reaction method was used to synthesize the polycrystalline Eu 3 B 2 O 6 , 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 (-Δ S M ), temperature averaged entropy change ( TEC ) as well as the refrigeration capacity ( RC ) for Eu 3 B 2 O 6 . Under the field change from 0 to 5 T, the maximal values of -Δ S 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 Eu 3 B 2 O 6 compound a promising candidate for cryogenic magnetic refrigeration.

Keywords: Europium (II) compounds, Magnetic entropy change, Magnetocaloric effect material, Cryogenic magnetic refrigeration