Abstract. The electrical conductivity of Bi 3 Zn 2 Sb 3 O 14 pyrochlore was studied as a function of temperature and partial pressure of oxygen. Conductivity measurements by ac complex impedance analysis and ionic transference number measurements show this pyrochlore to be a mixed ionic-electronic conductor with an energy band gap of 3.15 ± 0.9 eV. A defect model in which Frenkel defects on the oxygen lattice are dominant is confirmed. Enthalpies of reduction, oxidation and the sum of oxygen vacancy formation and migration were found to be 4.82 ± 0.8 eV, 1.48 ± 1.0 eV and 1.67 ± 1.0 eV respectively.

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