High Temperature Crystal Chemistry and Oxygen Permeation Properties of the Mixed IonicElectronic 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
The high temperature crystal chemistry and oxygen permeation properties of the cation-ordered LnBaCo2O5+ perovskite oxideslanthanide Ln = Pr, Nd, and Sm have been investigated in comparison with the cation-disordered La0.5Ba0.5CoO3− perovskite.The LnBaCo2O5+ Ln = Pr, Nd, and Sm oxides exhibit a metal-insulator transition at T 200°C, as evidenced by totalconductivity measurements and high temperature X-ray diffraction data and an oxygen vacancy orderdisorder 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 mechanismin the Ln = Nd is bulk-diffusion-limited rather than surface-exchange-limited for membrane thickness L 1.1 mm.