A new series of Sr(Co,Fe,Zr)O3-δ Perovskite-type membrane materials for oxygen permeation

A new series of SrCo0.4Fe0.6-xZrxO3-delta (0.1 less than or equal to x less than or equal to 0.2) and SrCo0.95-xFexZr0.05O3-delta (0.1 less than or equal to x less than or equal to 0.8) oxides were synthesized by the solid-state reaction method. The incorporation of Zr and its effect on the crystal chemistry, oxygen permeation, and structural stability of SrCo(0.4)Fe(0.6-x)ZrxO(3-delta) have been investigated. Formation of the solid solutions with the cubic perovskite-type structure was found in the SrCo0.4Fe0.6-xZrxO3-delta oxide system in the range of 0 less than or equal to x less than or equal to 0.1. The incorporation of the proper content of Zr into SrCo0.4Fe0.6O3-delta suppressed the oxygen loss at high temperature and could stabilize the cubic structure of perovskite in a low oxygen partial pressure atmosphere, while the oxygen permeability of SrCo0.4Fe0.6-xZrxO3-delta membranes decreased with increasing Zr content. A total of 5 mol % of Zr cation dissolution was considered to be enough for the structural stability without deleteriously affecting the oxygen flux. Meanwhile, an investigation of the effect of the Co content on the oxygen permeation and structural stability of SrCo0.95-xFexZr0.05O3-delta series oxides showed that, with increasing Co content, the oxygen permeability increased, but no phase transition occurred in low oxygen partial pressure for all of the samples investigated. Our results indicated that the content of Zr played a critical role in the stability of Sr-Co-Fe-Zr-O series oxides. When good structural stability and oxygen permeation properties are combined, these Sr(Co,Fe,Zr)O3-delta oxides are considered to be promising candidates as oxygen separation membranes.