Conduction in Bi2O3-based oxide ion conductor under low oxygen pressure. II. Determination of the partial electronic conductivity

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In order to investigate the partial electronic conduction in the high oxide ion conductor of the system Bi2O3-Y2O3 under low oxygen pressure, e.m.f. and polarization methods were employed. Although the electrolyte was decomposed when the $$P_{{\text{O}}_{\text{2}} }$$ was lower than the equilibrium $$P_{{\text{O}}_{\text{2}} }$$ of Bi, Bi2O3 mixture at each temperature, the ionic transport number was found to be close to unity above that $$P_{{\text{O}}_{\text{2}} }$$ . The hole conductivity (σ p) and the electron conductivity (σ p) could be expressed as follows, $$\begin{gathered} \sigma _p \Omega cm = 5 \cdot 0 \times 10^2 \left( {P_{O_2 } atm^{ - 1} } \right)^{{1 \mathord{\left/ {\vphantom {1 4}} \right. \kern-\nulldelimiterspace} 4}} \exp \left[ { - 106 kJ\left( {RT mol} \right)^{ - 1} } \right] \hfill \\ \sigma _p \Omega cm = 3 \cdot 4 \times 10^5 \left( {P_{O_2 } atm^{ - 1} } \right)^{ - {1 \mathord{\left/ {\vphantom {1 4}} \right. \kern-\nulldelimiterspace} 4}} \exp \left[ { - 213 kJ\left( {RT mol} \right)^{ - 1} } \right] \hfill \\ \end{gathered} $$ These values were much lower than the oxide ion conductivity under ordinary oxygen pressure.