Electrical conductivity and oxygen permeation of Ag/BaBi8O13 composites

A sharp increase in the electrical conductivity of dual phase Ag/BaBi8O13 composites is observed in compositions with silver contents between 13 and 17 vol.%. Above this percolation threshold, composite membranes have high oxygen permeability in the temperature range 570≤T≤700°C. The oxygen flux is 20 times lower for a membrane composition with a conductivity below the percolation threshold. The drop in conductivity in BaBi8O13 at the β1 to β2 phase transition at 570°C is apparent in the permeation flux data. The overall permeation rate is limited by the surface reaction kinetics.