Structural Stability and Oxygen Permeation Properties of Sr3ÀxLaxFe2ÀyCoyO7Àd

F. PRADO; T. ARMSTRONG; A. CANEIRO; A. MANTHIRAM

JOURNAL OF THE ELECTROCHEMICAL SOCIETY

ELECTROCHEMICAL SOC INC

Año: 2001 vol. 148 p. 7 - 14

0013-4651

The structural stability and oxygen permeation properties of Sr32xLaxFe22yCoyO72d with 0 < x < 0.3 and 0 < y < 1.0 havebeen studied at high temperature (800 < T < 900°C) and in the oxygen partial pressure range 1025 < pO2 < 0.21 atm. Thesephases have a perovskite-related intergrowth structure with tetragonal symmetry, which does not change with temperature up to1000°C in the range 1025 < pO2 < 0.21 atm. The oxygen permeation flux of Sr32xLaxFe22yCoyO72d membranes increases withincreasing Co content, decreases with increasing lanthanum content, and does not change with time. Measurements of oxygenpermeation flux as a function of membrane thickness for Sr2.7La0.3Fe1.4Co0.6O72d at 900°C indicates the oxygen transport is bulklimited for this composition. Assuming that this observation is also valid for other compositions, the ionic conductivity, si , andthe vacancy diffusion coefficient Dv have been estimated. The structural stability and permeation properties ofSr32xLaxFe22yCoyO72d are compared with those of the perovskite phases SrFe0.2Co0.8O32d and Sr0.6La0.4Fe0.2Co0.8O32d .