Cation order enhancement in Sr2FeMoO6 by water-saturated hydrogen reduction

Sr2FeMoO6 (SFMO) double perovskite has been prepared from powders obtained by the polyacrylamide gel combustion synthesis. After removing organic residues, the precursor powder consists of a homogeneous submicronic blend of SrFeO3−x and SrMoO4. In order to crystallize SFMO an experimental setup consisting of injecting water-saturated Ar/5%H2 gas flow in a crucible was used. Results show that a high saturation magnetization of 3.9μB/formula unit, which accounts for 98% of the theoretical value, and Curie temperature of 415 K can be achieved in this way. The Fe/Mo order was 98% by Rietveld refinement of best sample. Furthermore, no metallic iron was detected, even at long reducing treatments. Lowering the reducing power of hydrogen with water is believed to be the main reason for improved synthesis.