Novel cobalt-free BaFe1−xGdxO3−δ perovskite membranes for oxygen separation. Issue 27 (21st June 2016)

• Record Type: Journal Article
• Authors: Lu, Yao; Zhao, Hailei; Chang, Xiwang; Du, Xuefei; Li, Kui; Ma, Yanhui; Yi, Sha; Du, Zhihong; Zheng, Kun; Świerczek, Konrad
• Is Part Of: Journal of materials chemistry. Volume 4:Issue 27(2016)
• Page Start: 10454
• Page End: 10466
• Publication Date: 2016-06-21
• Subjects: Materials -- Research -- Periodicals; Chemistry, Analytic -- Periodicals; Environmental sciences -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c6ta01749e
• Languages: English
• ISSNs: 2050-7488

Abstract

Abstract : Slight B-site Gd-doped BaFeO3− δ material exhibits impressive oxygen permeability and excellent long term stability. Abstract : A cobalt-free perovskite-type mixed ionic and electronic conductor (MIEC) is of technological and economic importance in many energy-related applications. In this work, a new group of Fe-based perovskite MIECs with BaFe1− x Gd x O3− δ (0.025 ≤ x ≤ 0.20) compositions was developed for application in oxygen permeation membranes. Slight Gd doping ( x = 0.025) can stabilize the cubic structure of the BaFe1− x Gd x O3− δ perovskite. The Gd substitution of BaFe1− x Gd x O3− δ materials increases the structural and chemical stability in the atmosphere containing CO2 and H2 O, and decreases the thermal expansion coefficient. The BaFe0.975 Gd0.025 O3− δ membrane exhibits fast oxygen surface exchange kinetics and a high bulk diffusion coefficient, and achieves a high oxygen permeation flux of 1.37 mL cm −2 min −1 for a 1 mm thick membrane at 950 °C under an air/He oxygen gradient, and can maintain stability at 900 °C for 100 h. Compared to the pristine BaFeO3− δ and the well-studied Ba0.95 La0.05 FeO3− δ membranes, a lower oxygen permeation activation energy and higher oxygen permeability are obtained for the 2.5 at% Gd-doped material, which might be attributed to the expanded lattice by doping large Gd 3+ cations and a limited negative effect from the strong Gd–O bond. A combination study of first principles calculation and experimental measurements was further conducted to advance the understanding of Gd effects on the oxygen migration behavior in BaFe1− x Gd x O3− δ . These findings are expected to provide guidelines for material design of high performance MIECs.