Conductivity and stability of ceramic Sr1-xYxFeO3-δ solid solutions

The total electric conductivity of two ceramics of cubic perovskites corresponding to x = 0.1 and x = 0.2 in the Sr1-xYxFeO3-delta 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 approximate to 0.1-0.2 eV to be extracted. The effect of the oxygen partial pressure (P-O2 = 0.21-10(-15) atm) on the conductivity of the Sr1-xYxFeO3-delta 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 P-o2-stability of Y0.2Sr0.8FeO3-delta has been determined. These results are discussed in terms of the defect structure in Sr1-xYxFeO3-delta, which accounts well for the present data and especially the sign change of the majority charge carriers as P-O2 is reduced. This study presents important new features of the total conductivity with respect to temperature and oxygen non-stoichiometry in these ceramics.