Mixed electronic and ionic conductivity of LaCo(M)O 3 (M=Ga, Cr, Fe or Ni) : I. Oxygen transport in perovskites LaCoO 3–LaGaO 3

• Published in: Solid state ionics Vol. 104; no. 1; pp. 67 - 78
• Main Authors: Kharton, V.V, Viskup, A.P, Naumovich, E.N, Lapchuk, N.M
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 1997
• Subjects: Ionic conductivity; Lanthanum cobaltite–gallate; Mixed conductor; Oxygen permeability; Perovskite; Perovskite; Mixed conductor; Oxygen permeability; Lanthanum cobaltite–gallate; Ionic conductivity
• ISSN: 0167-2738; 1872-7689
• DOI: 10.1016/S0167-2738(97)00397-4

The formation of a continuous series of solid solutions with a rhombohedrally-distorted perovskite type structure has been found in the pseudobinary oxide system LaCoO 3–LaGaO 3. Substitution of gallium with cobalt in the lanthanum gallate results in blocking oxygen ionic transport and increasing electronic conductivity. The activation energy of the electrical conductivity of the LaGa 1− x Co x O 3 ceramics ( x=0.2–0.6) is in the range 57–65 kJ mol −1. The thermal expansion coefficients increase regularly with the cobalt content and lie in the range from 11.2×10 −6 to 22.3×10 −6 K −1. Doping LaCoO 3 with gallium has been ascertained to lead to lower electronic conductivity and oxygen permeability. The results of electrical conductivity and electron paramagnetic resonance (EPR) studies suggest that introduction of gallium into the cobalt sublattice leads to insulating cobalt ions.