The crystal structure and magnetic properties for the ordered double perovskite oxides Sr2-xKxFeMoO6 (0 ≤ x ≤ 0.04) are investigated. X-ray powder diffraction studies reveal that all the samples are single phase and have the I4/m symmetry. The anti-site defect (AS) in double perovskite oxides of Sr2-xKxFeMoO6 may be adjusted by alkali metal element of K doping. The unit cell magnetization at 280 K is 1.12 μB for x = 0 and 1.26 μB for x = 0.04;
respectively. The cation-ordering and the FeO(1)Mo bond-angle play the competition roles on the magnetism in the doping system. © 2011 Elsevier Ltd. All rights reserved;