Low-temperature synthesis of Sr2FeMoO6 double perovskite; structure, morphology, and magnetic properties

Abstract Nanostructured Sr2FeMoO6 double perovskite was synthesized by the sol-gel combustion method. X-ray diffraction results showed that SrMoO4 starts to form at 450 °C, and the formation of single-phase double perovskite with a tetragonal I4/m space group occurs at a relatively low temperature of 750 °C. Rietveld refinement by FullProf software showed the mean crystallite size of 49 nm, and unit cell parameters of a = b = 5.577 A and c = 7.918 A for the synthesized Sr2FeMoO6. Analysis of the FTIR spectra revealed that with mechanical activation process, the peak corresponding to the C–O band at 2341 cm−1 vanishes and intensity of carboxyl group (1445 cm−1) and nitrate ions band (1396 cm−1) are affected. The presence of the peaks related to the vibration of metal ions bands at octahedral sites at 644 and 831 cm−1 confirms the evolution of Sr2FeMoO6 double perovskite structure. Scanning electron microscope images showed that the Sr2FeMoO6 powder processed at 750 °C in 5%H2/N2 atmosphere has a mean particle size of about 250 nm. It was observed that the saturation magnetization increases to the high value of 18 emu.g−1 in the ordered structure at 800 °C. High Curie temperature of 423 K in the prepared sample makes it a promising candidate for the magnetocaloric applications.