Mixed electronic and ionic conductivity of LaCo(M)O-3 (M = Ga, Cr, Fe or Ni). V. Oxygen permeability of Mg-doped La(Ga, Co)O3-delta perovskites

The LaGa1-x-yCoxMgyO3-delta solid solutions with rhombohedrally-distorted p erovskite structure were ascertained to form in the concentration range of 0 less than or equal to less than or equal to 0.10 at x = 0.60 and 0 less t han or equal to y less than or equal to 0.20 at x = 0.35-0.40. Increasing c obalt content results in increasing electrical conductivity and thermal exp ansion of the perovskites. Thermal expansion coefficients of the LaGa1-x-yC oxMgyO3-delta ceramics were calculated from the dilatometric data to vary i n the range of 12.4-19.8 X 10(-6) K-1 at 300-1100 K. Doping La(Ga,Co)O3-del ta solid solutions with magnesium leads to increasing oxygen nonstoichiomet ry, electronic and oxygen ionic conductivity. Oxygen permeation fluxes thro ugh LaGa1-x-yCoxMgyO3-delta membranes were found to be limited by the bulk ionic conduction and to increase with magnesium concentration, being essent ially independent of cobalt content. (C) 1999 Elsevier Science B.V. ALI rig hts reserved.