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 Sr2FeMoO6 is presented. Double-perovskite (Sr2-3xGdxBa2x)FeMoO6 (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 (Sr2−3xGdxBa2x)FeMoO6 samples showed that proportional variations in Fe3+/Fe2+ and Mo5+/Mo6+ 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 2T 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.