It was recalled that such materials were a new type of protonic conducting system in which both the cations and protons were mobile. Proton conductivities which were of the order of 0.01S/cm were measured at temperatures of between 300 and 600C. Two different proton coordination states and conduction mechanisms were suggested to exist in such systems.

B.Zhu, B.E.Mellander: Solid State Ionics, 1995, 77, 244-9