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Electrical conductivity and defect chemistry of $$ {\hbox{B}}{{\hbox{a}}_x}{\hbox{S}}{{\hbox{r}}_{{1} - x}}{\hbox{C}}{{\hbox{o}}_y}{\hbox{F}}{{\hbox{e}}_{{1} - y}}{{\hbox{O}}_{{3} - \delta }} $$ perovskites

Yáng, Zhèn ; Harvey, Ashley ; Infortuna, Anna ; Schoonman, Joop ; Gauckler, Ludwig

In: Journal of Solid State Electrochemistry, 2011, vol. 15, no. 2, p. 277-284

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    Titre
    • Electrical conductivity and defect chemistry of $$ {\hbox{B}}{{\hbox{a}}_x}{\hbox{S}}{{\hbox{r}}_{{1} - x}}{\hbox{C}}{{\hbox{o}}_y}{\hbox{F}}{{\hbox{e}}_{{1} - y}}{{\hbox{O}}_{{3} - \delta }} $$ perovskites
    Auteur
    • Yáng, Zhèn. Nonmetallic Inorganic Materials, Department of Materials, ETH Zurich, 8093, Zurich, Switzerland
    • Harvey, Ashley. Nonmetallic Inorganic Materials, Department of Materials, ETH Zurich, 8093, Zurich, Switzerland
    • Infortuna, Anna. Nonmetallic Inorganic Materials, Department of Materials, ETH Zurich, 8093, Zurich, Switzerland
    • Schoonman, Joop. Section Materials for Energy Conversion and Storage, Department Chemical Engineering, Delft University of Technology, Julianalaan 136, 2628 BL, Delft, The Netherlands
    • Gauckler, Ludwig. Nonmetallic Inorganic Materials, Department of Materials, ETH Zurich, 8093, Zurich, Switzerland
    Type de document
    • Postprint
    Langue
    • Anglais
    Publié dans
    • Journal of Solid State Electrochemistry, 2011, vol. 15, no. 2, p. 277-284. Springer-Verlag
    Autre version électronique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:316556
    Summary
    Bulk $$ {\hbox{B}}{{\hbox{a}}_x}{\hbox{S}}{{\hbox{r}}_{{1} - x}}{\hbox{C}}{{\hbox{o}}_y}{\hbox{F}}{{\hbox{e}}_{{1} - y}}{{\hbox{O}}_{{3} - \delta }} $$ compositions (BSCF) were synthesized by the solid-state reaction method. The electrical conductivity of ceramic bars was measured using a dc four-probe method as a function of temperature in air up to 970°C. All compositions showed thermally activated p-type semi-conductivity up to ~450°C and then a transition to metal-like conductivity. The small-polaron hopping p-type semi-conductivity depends on the oxygen nonstoichiometry, which increases with increasing temperature. Metal-like conductivity is attributed to the overlap of the transition metal d-electron orbitals with the oxygen p-orbitals. Strontium-rich compositions show higher conductivity. The Co/Fe ratio does not influence much the p-type semi-conduction. Iron-rich compositions revealed more metal-like conduction behavior. The degree of overlap between transition metal d-orbitals and oxygen p-orbitals depends on the Ba/Sr as well as on the Co/Fe ratios