High Temperature, Crystal Chemistry and Oxygen permeation Properties of the Mixed ionic-Electronic Conductors LnBaCo2O5+d (Ln= Lanthanide).

J. -H. KIM; L. MOGNI; F. PRADO; A. CANEIRO; J.A:ALONSO; A. MANTHIRAM

JOURNAL OF THE ELECTROCHEMICAL SOCIETY

ELECTROCHEMICAL SOC INC

Año: 2009 vol. 156 p. 1376 - 1382

0013-4651

The high temperature crystal chemistry and oxygen permeation properties of the cation-ordered LnBaCo2O5+d perovskite oxides lanthanide Ln = Pr, Nd, and Sm have been investigated in comparison with the cation-disordered La0.5Ba0.5CoO3-d perovskite. The LnBaCo2O5+d Ln = Pr, Nd, and Sm oxides exhibit a metal-insulator transition at T 200°C, as evidenced by total conductivity measurements and high temperature X-ray diffraction data and an oxygen vacancy order–disorder transition at T 350°C in air, as evidenced by an orthorhombic to tetragonal transition. At a given temperature, the oxygen permeation flux decreases from Ln = La to Nd to Sm due to the changes in crystal symmetry and lattice strain. The oxygen permeation mechanism in the Ln = Nd is bulk-diffusion-limited rather than surface-exchange-limited for membrane thickness L 1.1 mm.