B-site La-doped BaFe_0.95-xLa_xZr_0.05O _3-δ perovskite-type membranes for oxygen separation

authored by

Fangyi Liang, Kaveh Partovi, Heqing Jiang, Huixia Luo, Jürgen Caro

Abstract

Partial La-substitution for Fe on the B-site of the perovskite BaFe _0.95-xLa_xZr_0.05O_3-δ (BFLZ) was achieved by applying a sol-gel synthesis method. The highest La content in BFLZ for the formation of a pure cubic perovskite structure without any detectable impurities is about x = 0.04. It is found for the first time that the introduction of La on the B-site of a mixed oxide stabilizes the cubic structure. Furthermore, the formation of the cubic structure of BFLZ increases significantly the oxygen permeability. The maximum oxygen permeation flux is found for a La-content of x = 0.04 with the largest volume of the cubic unit cell, reaching 0.63 and 1.24 cm³ (STP) min^-1 cm ^-2 for a 1.1 mm thick membrane at 750 and 950 °C, respectively. This finding is in complete agreement with the XRD structure analysis, showing that the highest B-site La-substitution of BFLZ under conservation of the pure cubic perovskite phase without forming any foreign phase was about x = 0.04. For BFLZ with x > 0.04, the secondary phase Ba₆La₂Fe ₄O₁₅ forms increasingly and the oxygen permeation flux decreases. The influence of the sweep gas flow rates on the oxygen permeation flux and the oxygen ionic conductivity were found to be in good agreement with the Wagner theory, indicating the oxygen ion bulk diffusion as a rate-limiting step of oxygen transport. Stable oxygen permeation fluxes were obtained during the long-term oxygen permeation operation of the BFLZ (x = 0.04) membrane over 170 h at 750 and 950 °C, respectively.

Organisation(s)

Institute of Physical Chemistry and Electrochemistry

External Organisation(s)

Max-Planck-Institut für Kohlenforschung

Type

Article

Journal

Journal of Materials Chemistry A

Volume

1

Pages

746-751

No. of pages

6

ISSN

2050-7488

Publication date

2013

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

General Chemistry, Renewable Energy, Sustainability and the Environment, General Materials Science

Sustainable Development Goals

SDG 7 - Affordable and Clean Energy

Electronic version(s)

https://doi.org/10.1039/c2ta00377e (Access: Closed)