dc Electrical Degradation of Perovskite‐Type Titanates: II, Single Crystals

The resistance degradation of Al‐doped, Ni‐doped, and Fedoped SrTiO 3 single crystals is studied as a function of the temperature and the applied dc voltage. The individual influence of the acceptor dopants is discussed. Data of the mobility of oxygen vacancies are obtained from the determination of the time evolution of the electric field distribution between the electrodes, from electrocoloration studies, and from an examination of the thermal annealing after degradation. In a numerical calculation based on the defect chemistry and transport properties of titanates, the electrocoloration process is simulated and a qualitative explanation of the degradation process is presented.