High Temperature Crystal Chemistry and Oxygen Permeation Properties of the Mixed Ionic–Electronic Conductors LnBaCo2O5+
„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 fluxdecreases 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.