It was pointed out that, in the same way that defect chemistry governed internal thermodynamics and bulk properties, a defect chemistry of boundary regions was needed when interfacial effects were considered. It was suggested how this could be achieved in general for a mixed ionic-electronic conductor. Emphasis was placed on ionic conductivity anomalies in heterogeneous systems, and sensing effects which involved solid ion conductor surfaces.

J.Maier: Solid State Ionics, 1995, 75, 139-45