DEFECT CHEMISTRY AT INTERFACES

It is shown, theoretically and experimentally, how defect thermodynamics can be extended to boundary layers. Defect profiles and conductivity effects can be calculated for the ideal case where the background structure (structure besides perturbations stemming from defects) behaves in a step function way. In this manner, many conductivity anomalies in multiphase and polycrystalline ionically conducting systems can be explained. The consideration of the interface ionic conductor/gas leads to a new sensor principle for acid-base active gases. Moreover, drastic catalytic effects of heterogeneously doped AgCl in organic elimination reactions can be predicted and verified. A special discussion is devoted to mesoscopic systems and to the problem of minority charge carriers.