Surface conductivity measurements on AgCl single crystals using microelectrodes

A sensitive method to detect highly conducting surface layers on macroscopic solid electrolyte single crystals is described: Impedance measurements using circular microelectrodes of varying diameter (5-20 mu m) permit a quantitative evaluation of the conductivity and the thickness of surface layers. Imprint geometry and surface topology are measured by atomic force microscopy (AFM). Additional temperature dependent measurements of the point contact resistance yield the activation energy of the relevant transport process. The applicability of the method is demonstrated at the example of a highly conducting surface layer on AgCl caused by mechanical treatment. The effect is discussed in terms of defects of different dimensionality and different kinetic barriers.