Magnetocaloric properties of the A-site co-doping double-perovskite of Sr2FeMoO6

In this paper, the effect of Gd/Ba co-doping on magnetocaloric properties for Sr 2 FeMoO 6 is presented. Double-perovskite (Sr 2-3x Gd x Ba 2x )FeMoO 6 (0.00 ≤  x  ≤ 0.20) were prepared by the solid reaction method. X-ray diffraction results showed that all samples were single phase and belonged to I4/m space group. X-ray photoelectron spectroscopy analysis of (Sr 2−3x Gd x Ba 2x )FeMoO 6 samples showed that proportional variations in Fe 3+ /Fe 2+ and Mo 5+ /Mo 6+ were found under Gd/Ba co-doping. Field-cooled magnetization curves indicated that Gd/Ba co-doping led to the Curie temperature ( Tc ) drop from 394 K to 357 K. Arrot plots analysis of samples revealed a second-order magnetic transition. The magnetic entropy change of all samples increased initially and then decreased with temperature, and all samples exhibited the maximum magnetic entropy change near Tc . The maximum magnetic entropy change of samples in the magnetic field of 2 T decreased from 0.72 J K −1  kg −1 to 0.54 J K −1  kg −1 because of Gd/Ba co-doping. Relative cooling power decreased correspondingly.