The precursor phases of SrFeO3–x and SrMoO4 were used to prepare Sr2FeMoO6 with different ratios by a solid-state reaction technique. An X-ray diffractometer was used to identify the phases. The SrMoO4 was observed to exist in the Mo-rich samples. The high resolution of a transmission electron microscope was employed to identify the compositions and phases. It was further evidenced that Mo-rich nanosized clusters were located inside the grains rather than at grain boundaries. Moreover, the antiphase boundary was clearly evidenced in the Mo-rich Sr2FeMoO6, which might lead to the Sr- or Fe-rich boundaries. The conduction, magnetic, and magnetotransport properties were characterized, and it was found that the Mo-rich samples had higher resistivity, lower saturated magnetization, and lower coercivity but higher low-field magnetoresistance, which was strongly related to the presence of the excess Mo ions and antiphase boundaries within the grains. The conduction of Sr2FeMoO6 samples with different ratios revealed semiconducting behavior, which could be described by the VRH model. It was suggested that the enhancement of low-field magnetoresistance of Mo-rich Sr2FeMoO6 arose from the antiphase boundaries or the induced Sr- or Fe-rich grain boundaries.

Reassessment of the Role of Antiphase Boundaries in the Low-Field Magnetoresistance of Sr2FeMoO6. T.T.Fang: Physical Review B, 2005, 71[6], 064401 (7pp)