Electrical and Magnetic Properties of the System SrFeO 3 –BiFeO 3

Perovskite phases containing iron in both the tetravalent and trivalent states were prepared by equilibration at high oxygen pressures. Small bismuth additions to SrFeO 3 resulted in high conductivity (10 1 to 10 3 (ohm‐cm) –1 at 26°C) and antiferromagnetic order below 130°K. Distortion to tetragonal symmetry occurs approximately at the composition Bi 0.3 Sr 0.7 FeO 2.87 , but higher bismuth concentrations (up to 80 mole %) give rise to a second cubic phase region which shows decreased conductivity (∼10 –5 (ohm‐cm) –1 ) and weak ferromagnetism with ordering temperatures higher than 26°C. Rhombohedral specimens Bi 0.9 Sr 0.1 FeO 2.96 and BiFeO 3.01 are anti‐ferromagnetic and have comparatively low conductivity.