Analysis of conductivity in 8YSZ ceramics during AC-flash processes: A two-barrier ionic transport model approach

This work offers a systematic study of the electrical conductivity in dense 8 mol% yttria-stabilized zirconia (8YSZ) during non-isothermal and isothermal AC-flash conditions under a fixed applied voltage. Conductivity data were interpreted using a two-barrier ionic transport model which is able to capture the non-Arrhenius behavior commonly found for 8YSZ. The analysis of the conductivity evolution indicates that AC-flash in 8YSZ may be understood as a time-dependent breakdown process where the field exposure duration plays a critical role, driven by similar charge transport mechanisms regardless of the employed methodology. A characteristic sequence of electrical resistance degradation, previously described for 8YSZ subjected to DC fields, is also observed under AC fields, suggesting the involvement of partial discharge mechanisms and charge accumulation effects in the formation of conductive paths eventually leading to the flash event. These findings highlight the limitations of time-independent conductivity models to fully describe AC-flash processes in 8YSZ ceramics.