Measurements were made of the drift mobility of Ag ions on the surface of oxide samples which were maintained at temperatures of between 400 and 500C in air. Silver contacts were placed on the surface in the form of an inner circular anode and an outer concentric-ring cathode. By measuring the outward advancement of Ag, the mobility could be determined. The measurements were made as a function of temperature, field intensity, surface roughness, and O content of the air. The drift-mobility values ranged from 10-8 to 10-5cm2/Vs. It was deduced that the dynamic formation of surface oxide (Ag2O was unstable above 300C) was important in understanding Ag migration.

W.M.Sears, D.A.Love: Physical Review B, 1993, 47[19], 12972-5