MIXED ELECTRONIC/IONIC CONDUCTIVITY OF THE SOLID-SOLUTION LA(1-X)SRXCO(1-Y)NIYO3-DELTA (X= 0.4, 0.5, 0.6 AND Y= 0.2, 0.4, 0.6)

The effect of Sr and Ni substitution on the mixed electronic/ionic conductivity was investigated in a series of the perovskite-type oxides La(1-x)SrxCo(1-y)NiyO3-delta(x:0.4, 0.5, 0.6 and y:0.2, 0.4, 0.6) prepared. Electrical conductivity was measured, in air, by a four-point probe technique, within the temperature range 500-1000-degrees-C Oxygen self-diffusion coefficient (D*), activation energy (E(a)), and surface exchange (k) data were obtained, by combining the isotopic O-18/O-16 exchange diffusion profile (IEDP) technique, at 700, 800 and 900-degrees-C, with the secondary ion mass spectroscopy (SIMS) technique for the O-18 depth profile measurement. The results derived suggest that the present perovskite-type oxides are excellent mixed conductors, having high electronic conductivity in addition to their high O-2- self-diffusivity. Oxygen flux through the material was principally controlled by the surface exchange kinetics. As far as the effect of Sr and Ni substitution on the electrical properties is concerned, a strong interdependence was found between the dopant's content.