The impact of structural features on ion and electron transport in Y0.25Sr0.75FeO3−δ

•Structure, oxygen content, and charge transport in Y0.25Sr0.75FeO3−δ is studied.•Incommensurate modulation with ±q ~0.42 〈100〉p* is revealed by electron diffraction.•The feature originates from the large difference in the sizes of Y3+ and Sr2+ cations.•Structural distortion is found to promote oxygen deficiency in Y0.25Sr0.75FeO3−δ.•Decreased ion and hole conductivity is also related to structural features. The electron diffraction study of cubic perovskite-type Y0.25Sr0.75FeO3−δ revealed an incommensurate modulation with ±q ~0.42 〈100〉p*, which is assumed to originate from a strong steric disturbance due to a large difference in the sizes of Y and Sr cations. The oxygen content and electrical conductivity in Y0.25Sr0.75FeO3−δ were measured and analyzed, and a comparison with similar data for Nd0.25Sr0.75FeO3−δ was performed. The oxygen content in Y0.25Sr0.75FeO3−δ equilibrated with ambient conditions (2.775 ± 0.005) was found to be substantially lower than that in Nd0.25Sr0.75FeO3−δ (2.951 ± 0.005), although both values were equal to 2.625 at 950 °C and oxygen partial pressure ~10−9 atm. The oxygen-ion and p-type conductivity in Y0.25Sr0.75FeO3−δ was found to be 2.5 and 3 times, respectively, lower than in Nd0.25Sr0.75FeO3−δ. The revealed strong deviations in properties of Y0.25Sr0.75FeO3−δ are argued to be associated with its structural features.