Dense composites were fabricated for use as O separation membranes. A density about 95% was achieved for a sintering temperature of 1350C. An insulating La2Zr2O7 phase formed during the high-temperature sintering. A percolation threshold was identified at about 30wt% (or 28vol%) of (La,Sr)MnO3. Isotopic exchange depth profiling secondary ion mass spectrometry was used to investigate O diffusion and surface exchange properties. The composites, YSZ–30wt%LSM and YSZ–40wt%LSM (or 38vol%LSM), with a 3-dimensional interconnected network, exhibited a higher O diffusivity than pure (La,Sr)MnO3, but one which was slightly lower than that of the parent YSZ. The O surface exchange coefficient of the YSZ was markedly enhanced by the introduction of the electronic conductor LSM; which confirmed the supposition that the availability of electrons limited the O surface exchange reaction on pure YSZ materials.

Electrical Properties and Oxygen Diffusion in Yttria-Stabilised Zirconia (YSZ)–La0.8Sr0.2MnO3±δ (LSM) Composites. Y.Ji, J.A.Kilner, M.F.Carolan: Solid State Ionics, 2005, 176[9-10], 937-43