CHARGE-TRANSPORT AND CHEMICAL DIFFUSION INVOLVING BOUNDARIES

Four specific examples are considered which highlight the role of inte rfaces in ionic crystals. They also refer to basic differences of soli ds and liquids which can be traced back to the rigidity and periodicit y of the crystalline matter. The examples are: (i) selective blocking of ionic and electronic carriers by specific electrodes, (ii) electrod e kinetics at a triple phase (gas, electrode, solid electrolyte) bound ary, (iii) conductivity of space charge layers in the direction perpen dicular and parallel to the interface and (iv) chemical diffusion thro ugh the grain boundary.