Abstract
The total electric conductivity of two ceramics of cubic perovskites corresponding to x = 0.1 and x = 0.2 in the Sr1-xYxFeO3-δ solid solution has been measured by a 4-probe method in the temperature range from 298 K to 1373 K in air, allowing activation energies of ≈0.1–0.2 eV to be extracted. The effect of the oxygen partial pressure (PO2 = 0.21–10−15 atm) on the conductivity of the Sr0.8Y0.2FeO3-δ ceramic has also been investigated at high temperatures, i.e. at 1123 K, 1223 K and 1323 K. By analyzing the X-ray diffraction patterns of the quenched powder samples, the Po2-stability of Y0.2Sr0.8FeO3-δ has been determined. These results are discussed in terms of the defect structure in Sr1-xYxFeO3-δ, which accounts well for the present data and especially the sign change of the majority charge carriers as PO2 is reduced. This study presents important new features of the total conductivity with respect to temperature and oxygen non-stoichiometry in these ceramics.
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