Crystal structure and magnetic properties characterization of double-perovskite compounds Sr2Ga1-xMnxMoO6 (x=0, 0.1, 0.2, 0.3)

Polycrystalline Sr2Ga1-xMnxMoO6 (x=0, 0.1, 0.2, 0.3) compounds were obtained through using nonmagnetic Ga3+ to instead of Mn2+ in Sr2MnMoO6. The effect of Ga3+ on the structure and magnetic properties of Sr2MnMoO6 was studied by means of XRD and magnetization measurements. Rieveld refinement results of XRD show that the Sr2Ga1-xMnxMoO6 (x=0, 0.1, 0.2, 0.3) series of compounds crystallize in tetragonal symmetry (space group I4/m). With the increasing of Ga3+ doping, the degree of B/B' cation order decreases, a shrink of the average bond distance and an enlargement of the average bond distance are found, the average 1-Mo> bond angles of 180° are not changed and the average 2-Mo> bond angle sightly increases. The magnetic measurements in 5 K and 300 K suggest that these compounds are antiferromagnetism, and at low temperature (5 K) these low-doped compounds show weak ferromagnetic properties. These results show that the election doping of Ga3+ to Mn2+ can cause the change of the ionic valence from Mo5+ to Mo6+.