Magnetocaloric properties of double-perovskite Sr1.98Al0.02FeMoO6

Abstract In this paper, we concluded a series of studies on the magnetic properties of double-perovskite Sr 2 FeMoO 6 and Sr 1.98 Al 0.02 FeMoO 6 . Samples were prepared by a sol-gel method. Analysis of the X-ray diffraction data showed that both samples were monophasic and belonged to the I 4/ m space group. By analysing the scanning electron microscope patterns, we found that doping of aluminium reduced the average grain size of samples from 889 nm to 831 nm. The magnetic hysteresis loop of the samples at 5 K indicated that saturation magnetization did not change significantly with doping. Field-cooled magnetization curves showed that Al doping caused the Curie temperature ( T C ) of the samples to drop from 386 K to 356 K. Arrott plot analysis indicated that the magnetic phase change of both samples was a second-order magnetic phase transition. The maximum magnetic entropy change | S M max | of the samples in the magnetic field of 2.5 T increased from 0.559 J kg −1 K −1 to 0.589 J kg −1 K −1 , and the relative cooling power also increased for the doped sample.