Grain boundary effects on the magneto-transport properties of Sr2FeMoO6 induced by variation of the ambient H2–Ar mixture ratio during annealing

Abstract Using the sol–gel method, polycrystalline double perovskites Sr 2 FeMoO 6 with nanometer-scale grain size have been synthesized in the ambience of a controlled stream of different gaseous H 2 –Ar mixtures during annealing. X-ray diffraction (XRD) results indicated that with an increasing proportion of H 2 , the component of the SrMoO 4 impurity present in the crystallites first decreased, but then increased again with further increase of the H 2 proportion. The XRD results were further supported by independent sample analysis using Raman spectroscopy. Systematic investigation of the transport properties of the samples indicated that the SrMoO 4 impurity at the grain boundary played a key role in determining the measured resistance and magnetoresistance of Sr 2 FeMoO 6 . This impurity effect was found to be correlated to the variation of the mixture ratio of the ambient H 2 –Ar gas stream surrounding the sample during annealing.