Fast diffusion of silver ions in potassium-doped glass

Abstract

Silver was doped by the solid-state ion-exchange method to glass surface that previously doped with potassium by salt bath method. The results of cross-sectional elemental analysis show that silver-doped depth after potassium doping was smaller compared to that without potassium doping. In contrast, the silver-doped area was much larger than that of silver foil used for the doping, indicating that the silver ions diffused rapidly in the direction perpendicular to the applied electric field, i.e., parallel to tha glass surface. Thus, the effect of silver doping duration on ionic distribution of potassium, sodium and silver in the area outside the silver foil was examined. As a result, it was found that potassium and sodium moved in the depth direction, while silver moved to horizontal direction. Furthermore, silver migrated not only in the horizontal direction but also in the depth direction, albeit over short distances. And as the doping time increased and silver caught up with the doping depth of potassium, the doping rate of silver in the depth direction increased. These result suggests that potassium acts as a barrier against silver migration.ion.