Oxygen ion conductivity of La_0.8Sr_0.2Ga_0.83Mg_0.17-xCo_xO_3-δ synthesized by laser rapid solidification

Materials La_0.8Sr_0.2Ga_0.83Mg_0.17-xCo_xO_3-δ with x=0, 0.05, 0.085, 0.10, and 0.15 are synthesized by laser rapid solidification. It is shown that the samples prepared by laser rapid solidification give rise to unique spear-like or leaf-like microstructures which are orderly arranged and densely packed. Their electrical properties each show a general dependence of the Co content and the total conductivities of La_0.8Sr_0.2Ga_0.83Mg_0.085Co_0.085O_3-δ prepared by laser rapid solidification are measured to be 0.067, 0.124, and 0.202 S·cm^-1 at 600, 700, and 800 ℃, respectively, which are much higher than by conventional solid state reactions. Moreover, the electrical conductivities each as a function of the oxygen partial pressure are also measured. It is shown that the samples with the Co content values ≤ 8.5 mol% each exhibit basically ionic conduction while those for Co content values ≥ 10 mol % each show ionic mixed electronic conduction under oxygen partial pressures from 10^-16 atm (1 atm=1.01325×10⁵ Pa) to 0.98 atm. The improved ionic conductivity of La_0.8Sr_0.2Ga_0.83Mg_0.085Co_0.085O_3-δ prepared by laser rapid solidification compared with by solid state reactions is attributed to the unique microstructure of the sample generated during laser rapid solidification.