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 con ductivity was investigated in a series of the perovskite-type oxides L a(1-x)SrxCo(1-y)NiyO3-delta(x:0.4, 0.5, 0.6 and y:0.2, 0.4, 0.6) prepa red. Electrical conductivity was measured, in air, by a four-point pro be technique, within the temperature range 500-1000-degrees-C Oxygen s elf-diffusion coefficient (D), activation energy (E(a)), and surface exchange (k) data were obtained, by combining the isotopic O-18/O-16 e xchange diffusion profile (IEDP) technique, at 700, 800 and 900-degree s-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-diffu sivity. Oxygen flux through the material was principally controlled by the surface exchange kinetics. As far as the effect of Sr and Ni subs titution on the electrical properties is concerned, a strong interdepe ndence was found between the dopant's content.