| Abstract Scope |
While Y-stabilized zirconia (YSZ) is a fast oxygen conductor and Fe-doped strontium titanate (STO) a p-type semiconductor, representing two extremes of oxide conductors, surprisingly their DC electrical degradation, or resistance breakdown, in highly accelerated lifetime tests (HALT) is phenomenologically indistinguishable. Our more detailed study, however, revealed that YSZ degrades by raising the electron chemical potential at the redox boundary to reach a two-phase, thermodynamic, metal-insulator transition level, even though the insulator side remains mostly unchanged. In contrast, STO forms a p-n junction by oxygen vacancy demixing, but the late-stage-demixing kinetics can be so sluggish that the steady state is not reached in low-temperature HALT. In STO, in particular, needle-like degradation paths often form, which explains the strong field dependence and large variation of lifetimes. These results provide new insight on related processes, such as flash sintering and melt processing of ceramics as well as resistance memory of oxide thin films. |