La0.58Sr0.4Co0.2Fe0.8O3-δ (LSCF), deposited on a metallic porous support by means of plasma spray-physical vapor deposition (PS-PVD) is a promising candidate for oxygen-permeation membranes. However, after O2 permeation tests, membranes show vertical cracks leading to leakage during these tests. In this work, a feature leading to crack formation has been identified. More specifically; Membrane residual stress changes during thermal loading have been found to be related to a phase transformation in the support. In order to improve the performance of the membranes, the metallic support has been optimized by applying an appropriate heat treatment. Additionally, it has been found that coatings deposited at lower oxygen partial pressures consist of 70% cubic and 26% rhombohedral perovskite phases. This increases the non-stoichiometry, which drives the formation of non-perovskite phases during annealing, affecting the membrane stability and the ionic conductivity. The amount of oxygen added during spraying can be used to suppress the cubic to tetragonal phase transformation.

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