Electrical conductivity and oxygen sensing behavior of SrSn1−xFexO3−δ (x = 0–0.2)

SrSn1−xFexO3−δ (x = 0, 0.05, 0.1, 0.15 and 0.2) exhibiting cubic structure (S.G.: P23) have been prepared by solid state route. Electrical conductivity increases with Fe concentration. Activation energy Ea values deduced from the Arrhenius plots of the respective compositions are in the range of 0.4–0.45 eV which imply that the mechanism of electrical conduction is same for all the compositions except for x = 0. X-ray photoelectron spectroscopy studies reveal that the valence states of Sr, Sn and oxygen are respectively +2, +4 and −2. Mossbauer spectroscopy studies reveal that Fe-ions in tetravalent, trivalent and divalent states with their relative proportion remain more or less same across the compositions. The increase in conductivity is due to lower valence Fe-ions. Among these compositions, SrSn0.85Fe0.15O3−δ exhibits significant changes in conductivity as function of oxygen partial pressure and becomes a promising composition for percentage level oxygen sensor as revealed by the sensor studies.

Research highlights▶ Structural and electrical conductivity of SrSn1−xFexO3−δ (x = 0, 0.05, 0.1, 0.15 and 0.2). ▶ Valence states of Sr, Sn and oxygen in SrSn1−xFexO3−δ (x = 0, 0.05, 0.1, 0.15 and 0.2) using XPS. ▶ Mossbauer studies on Fe in SrSn1−xFexO3−δ (x = 0, 0.05, 0.1, 0.15 and 0.2). ▶ Oxygen sensing characteristics of SrSn1−xFexO3−δ (x = 0.1, 0.15 and 0.2).