Oxygen ionic conductivity of Ti-containing strontium ferrite

• Published in: Solid state ionics 2000-08, Vol.133 (1), p.57-65
• Main Authors: Kharton, V.V, Viskup, A.P, Kovalevsky, A.V, Jurado, J.R, Naumovich, E.N, Vecher, A.A, Frade, J.R
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Diffusion in solids; Electronic transport in condensed matter; Exact sciences and technology; Faradaic efficiency; Ionic conductivity; Mixed conductivity and conductivity transitions; Oxygen permeation; Perovskite; Physics; Self-diffusion and ionic conduction in nonmetals; Strontium ferrite–titanate; Transport properties of condensed matter (nonelectronic)
• ISSN: 0167-2738; 1872-7689
• DOI: 10.1016/S0167-2738(00)00738-4

The total electrical conductivity, oxygen permeability, Faradaic efficiency and thermal expansion of perovskite-type Sr 0.97Fe 0.80Ti 0.20O 3− δ were studied. The oxygen permeation through strontium ferrite–titanate ceramics was found to be limited by both bulk ionic conduction and surface exchange rates, similar to other Fe- and Ti-containing perovskites. Increasing iron content in the system Sr 0.97(Ti,Fe)O 3− δ leads to a considerable increase in oxygen ionic and electronic conductivities, and thermal expansion. The ion transference numbers of Sr 0.97Fe 0.80Ti 0.20O 3− δ were determined by the Faradaic efficiency measurements, and estimated from the oxygen permeability data. Typical values of the transference numbers vary in the range from 4×10 −3 to 1.5×10 −2 at 973–1223 K, decreasing with reducing temperature. The oxygen ionic conductivity of Sr 0.97Fe 0.80Ti 0.20O 3− δ is close to the conductivity of the Zr 0.92Y 0.08O 1.96 solid electrolyte. The average thermal expansion coefficient of strontium ferrite–titanate, calculated from dilatometric data, is (13.8±0.1)×10 −6 K −1 at 300–780 K and (27.0±0.4)×10 −6 K −1 at 780–1040 K.