Physicochemical properties and mixed electronic and ionic conduction of composite ceramics in the system ZrO2-Bi2CuO4-Bi2O3 |
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Authors: | N. V. Lyskov Yu. G. Metlin K. I. Astaf’eva Yu. D. Tret’yakov L. S. Leonova Yu. A. Dobrovol’skii |
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Affiliation: | (1) Moscow State University, Vorob’evy Gory 1, Moscow, 119992, Russia;(2) Institute of Problems of Chemical Physics, Russian Academy of Sciences, pr. akademika Semenova 1, Chernogolovka, Moscow oblast, 142432, Russia |
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Abstract: | Composites ZrO2-(Bi2CuO4+ 20 wt % Bi2O3) (50–80 vol % ZrO2) are synthesized and their physicochemical properties are studied. It is demonstrated that the composites comprise triple-phase mixtures of ZrO2 of a monoclinic modification, Bi2CuO4, and solid solution Bi2?x Zr x O3 + x/2 and retain their mechanical strength up to 800°C. Impedance spectroscopy is used to examine their electroconductivity at 700–800°C in the interval of partial oxygen pressures extending from 37 to 2.1 × 104 Pa. Contributions made by electronic and ionic constituents to their overall conductivity are evaluated. The best specimens’ conductivity is ~0.01 S cm?1, with the electronic and ionic transport numbers nearly equal. The composite consisting of 50 vol % ZrO2 and 50 vol % (Bi2CuO4 + 20 wt % Bi2CuO4) is tested in the role of an oxygen-separating membrane. The selective flux of oxygen in the temperature interval 750–800°C amounts to (2.2–6.3) × 10?8 mol cm?2 s?1, testifying that these materials may be used as gas-separating membranes. |
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Keywords: | mixed electronic and ionic conduction ceramic composite impedance spectroscopy oxygen penetrability |
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