Phase interaction and oxygen transport in oxide composite materials

Abstract

Abstract The oxygen permeability of oxide composite membranes containing similar volume fractions of the components, including (La0.9 Sr0.1)0.98 Ga0.8 Mg0.2 O3-δ(LSGM)–La0.8 Sr0.2Fe0.8Co0.2O3-δ (LSFC), LSGM–La2Ni0.8Cu0.2O4+δ (LNC), SrCoO3-δ–Sr2Fe3O6.5 ±δ, Ce0.8Gd0.2O2-δ (CGO)–LSFC and CGO–La0.7Sr0.3MnO3-δ (LSM), was studied at 973–1223 K. In most cases, oxygen transport is substantially affected by component interaction, decreasing ionic conductivity due to cation interdiffusion, and formation of intermediate phases and/or blocking layers at grain boundaries. This interaction is maximised in systems where the phase components have similar structure and thus may form continuous solid solutions, for example LSGM–LSFC, or intermediate compounds such as Roddlesden–Popper phases in LSGM–LNC composites. The results show that, in addition to knowledge of the transport properties and volume fractions of percolating phases, analysis of ionic conduction in oxide composite materials requires assessment of phase interaction and grain boundary processes.