Electronic-ionic Impedance Characteristics of (Y0.08Sr0.92)1-xTi0.6Fe0.4O3-δ Mixed Conductor postprint

Abstract: A single phase A-site-deficient perovskite (Y0.08Sr0.92)1-xTi0.6Fe0.4O3-δ (x=0.05, 0.07, 0.10) was synthesized at 1350 oC in air by sol-gel method. The effect of A-site deficiency in (Y0.08Sr0.92)1-xTi0.6Fe0.4O3-δ on its phase structure, electrical and ionic conductivity and impedance was investigated. The partial oxygen ionic conductivity decreases with the increasing A-site deficiency, which may be attributed to the tendency for oxygen vacancy ordering. The n-type electronic conductivity in air increases with the increasing A-site deficiency, which may be attributed to the decrease of [Fe'Ti] and [h∙] due to the possible ionization reaction of ferric iron. The total electrical conductivity of (Y0.08Sr0.92)1-xTi0.6Fe0.4O3-δ (x=0.05, 0.07, 0.10) varies from 0.11 S·cm-1 to 0.26 S·cm-1 at 800oC. Only one oblique line in high frequency range for each temperature is presented, demonstrating that the electronic conductivity should mainly contribute to the total electrical conductivity. The increase of A- site deficiency is unfavorable for ion conductivity due to a subsequently rising relaxation time.