Structure, magnetic properties and cryogenic magnetocaloric performances of perovskite-type Gd(4TM0.25)O3 and Gd(5TM0.2)O3 high-entropy oxides

We herein fabricated two gadolinium-transition metal-based high entropy (HE) oxides of Gd(Mn0.25Fe0.25Al0.25Cr0.25)O3 [denoted as Gd(4TM0.25)O3] and Gd(Mn0.2Fe0.2Al0.2Co0.2Ni0.2)O3 [denoted as Gd(5TM0.2)O3] and determined their structural, magnetic, and magnetocaloric properties. Both of present HE oxides are found to crystallize in the single-phase perovskite-type orthorhombic structure with a homogeneous microstructure and exhibit prominent cryogenic magnetocaloric performances. The values of magnetic entropy change, refrigerant capacity, and temperature-averaged entropy change (6K-lift) under the magnetic field change of 0-7 T are estimated to be 20.34 J/kgK, 295.4 J/kg, and 19.56 J/kgK for Gd(4TM0.25)O3, and to be 22.45 J/kgK, 258.2 J/kg, and 20.79 J/kgK for Gd(5TM0.2)O3, respectively, which are comparable with recently reported candidate materials for practical magnetic cooling. These findings not only indicate potential applications of present perovskite-type Gd(4TM0.25)O3 and Gd(5TM0.2)O3 HE oxides, but also provide meaningful clues for exploring HE oxides with prominent cryogenic magnetocaloric performances.