The conductivity profiles of films which had been step-wise evaporated onto a sapphire substrate were measured. The films were annealed after each step. The bombardment of uncompleted films with Ar ions just before evaporation enhanced the ionic conductivity. The first film sheet (350nm-thick), adjacent to the interface, exhibited conductivity values of up to about 0.0001S/cm at 25C. The remaining part of each film, between 350 and 800nm from the interface, also exhibited an unexpectedly good conductivity. This was of the same magnitude as the highest conductivity value (6 x 10-6S/cm at 25C) which had then been found for disperse AgCl-Al2O3 systems. The measured activation energies  (0.34 to 0.47eV) of these films were markedly higher than the migration enthalpy (0.28eV) of Ag vacancies. It was suggested that the high conductivity and its profile were determined mainly by the microscopic structure of the films.

S.Mühlherr, K.Läuger, E.Schreck, K.Dransfeld, N.Nicoloso: Solid State Ionics, 1988, 28-30, 1495-505