摘要：The crystal structure, cryogenic magnetic properties, and magnetocaloric performance of double perovskite Eu
2NiMnO
6 (ENMO), Gd
2NiMnO
6 (GNMO), and Tb
2NiMnO
6 (TNMO) ceramic powder samples synthesized by solid-state method have been investigated. X-ray diffraction structural investigation reveal that all compounds crystallize in the monoclinic structure with a P2
1/n space group. A ferromagnetic to paramagnetic (FM-PM) second-order phase transition occurred in ENMO, GNMO, and TNMO at 143, 130, and 112 K, respectively. Maximum magnetic entropy changes and relative cooling power with a 5 T applied magnetic field are determined to be 3.2, 3.8, 3.5 J/kgK and 150, 182, 176 J/kg for the investigated samples, respectively. The change in structural, magnetic, and magnetocaloric effect attributed to the superexchange mechanism of Ni
2+–O–Mn
3+ and Ni
2+–O–Mn
4+. The various atomic sizes of Eu, Gd, and Tb affect the ratio of Mn
4+/Mn
3+, which is responsible for the considerable change in properties of double perovskite.
