info:eu-repo/semantics/article
Stabilization of the cubic perovskite in the system La1-xBa xCo1-yFeyO3-δ (0.7 ≤ x ≤ 0.9) and its electrochemical performance as cathode materials for intermediate-temperature solid oxide fuel cells
Fecha
2014-02-01Registro en:
Martinez, Cristian Fabricio; Prado, Fernando Daniel; de Florio, Daniel Zanetti; Caneiro, Alberto; Stabilization of the cubic perovskite in the system La1-xBa xCo1-yFeyO3-δ (0.7 ≤ x ≤ 0.9) and its electrochemical performance as cathode materials for intermediate-temperature solid oxide fuel cells; Elsevier Science; Journal of Power Sources; 247; 1-2-2014; 264-272
0378-7753
CONICET Digital
CONICET
Autor
Martinez, Cristian Fabricio
Prado, Fernando Daniel
de Florio, Daniel Zanetti
Caneiro, Alberto
Resumen
The effects of the substitution of Co by Fe on the crystal chemistry and electrode reaction of the system La1-xBaxCo 1-yFeyO3-δ (0.7 ≤ x ≤ 0.9), are investigated. The incorporation of Fe stabilizes the cubic perovskite and suppresses the structural transformation of La1-xBa xCoO3-δ from a metastable cubic perovskite to a hexagonal phase below 900 C. The linear expansion decreases with the replacement of Co by Fe. The lowest expansion coefficient value, α ∼ 20.5 × 10-6 K-1, was obtained for the samples with Fe content y = 0.6. AC impedance spectroscopy measurements on symmetrical cells reveal the presence of an intermediate (IF) and a low (LF) frequency contributions at T ≥ 600 C. The LF arc varies with the pO2, at 700 C, according to a power law with exponent n = -1, indicating oxygen diffusion through the porous of the electrode. The minimum Rp value (0.6 cm2 at 600 C) was obtained for La0.3Ba0.7Co0.6Fe 0.4O3-δ. At constant temperature, T = 750 C, only the IF contribution varies at a rate of 3 × 10-4 cm2 h-1, while the LF contribution remains constant. Experimental data suggest the growth of the IF arc is caused by the mismatch in the expansion coefficients of the electrode and electrolyte.