The phenomenon of Ag dissolution in this material was studied by using Raman scattering and high spatial resolution luminescence methods. The diffusion profile of excess Ag was investigated, and it was found that the diffusion flux of excess Ag, from the surface and into the bulk, was caused by the simultaneous movement of Ag+ ions and electrons; due to charge neutrality. It was shown that a low electron mobility limited the process of excess Ag diffusion. An ambipolar diffusion coefficient of 1.7 x 10-8cm2/s was measured, and its temperature dependence was explained in terms of the existence of self-trapped electrons.

S.Bredikhin, T.Hattori, M.Ishigame: Solid State Ionics, 1994, 67[3,4], 311-6