OXYGEN-ION CONDUCTION AND STRUCTURAL DISORDER IN CONDUCTIVE OXIDES

Defect-free crystals do not conduct ions. Increasing disorder initiall y translates into enhanced atomic transport. Heavily defective crystal s, however, often exhibit successively lower levels of atomic diffusiv ity as the defect level is increased. This dilemma may be addressed by considering that highly disordered solids tend towards order. Interes ting insights may be obtained by considering compounds with related st ructures which can be induced to go through order-disorder transitions either by change in temperature or composition. A number of such syst ems will be considered including materials with structures related to the fluorite and perovskite structures. The significance of these cons iderations on the application of such materials in solid state electro chemical devices will also be addressed as are the key contributions m ade by Arthur S. Nowick and co-workers towards our understanding of de fect-dopant interactions in such systems.