Synthesis, structure, electric transport and magnetic properties of Sr3Fe2−xNbxO7 (x = 0.3, 0.6 and 1.0)

Three new RP-type phases of the composition Sr3Fe1.7Nb0.3O7, Sr3Fe1.4Nb0.6O7 and Sr3FeNbO7 have been synthesized by the standard ceramic method. Their structure has been determined by Rietveld analysis of the powder X-ray diffraction data. The phases take up RP-type structure in the space group 14/mmm. The MO6 polyhedron is distorted. The study of electrical resistivity as a function of temperature suggests that these undergo insulator-metal transition. The magnetic susceptibility data show that the phases are anti-ferromagnetic in nature.