Evidence of ferroelectricity in SrFeO3−δ

Abstract Perovskite SrFeO 3−δ belongs to the Ruddlesden–Popper class of system exhibiting interesting electronic and magnetic properties. Nanocrystalline SrFeO 3−δ synthesized successfully by the thermal decomposition method has the cubic phase as confirmed from x-ray diffraction. The non-stoichiometric nature is confirmed from the selected area electron diffraction pattern. Oxygen stoichiometry, which plays an important role in determining the physical properties, was found to be 2.91 from the iodometric titration. Mössbauer measurement reveals paramagnetic behaviour and suggests mixed valence state of Fe. Relaxor type ferroelectricity is evident from the dielectric plots, which is also reflected in the thermal study. Relaxor ferroelectric behaviour is reported for the first time in SrFeO 2.91 , arising due to mixed valency of Fe ion.