Anomalous electrostriction degradation in Sm-doped ceria ceramics at room temperature

Ceria-based ceramics exhibit giant nonclassical electrostriction that is promising for high-performance electrostrictors, although their stability and reliability are rarely addressed and remain poorly understood. Here, we report anomalous electrostriction degradation in Sm-doped ceria (SDC) ceramics at room temperature. Under a modest AC electric field at 1 Hz, large electrostriction of 120 ppm is observed in pristine sample. Yet, after resting in ambient environment, electrostriction decreases by one order of magnitude without any electrochemical decomposition and phase transition. The oxygen vacancies are found to decrease in the degraded SDC as well, and the degradation does not occur at frequency of 500 Hz and higher, which exhibits electrostriction one order of magnitude smaller in the first place. We attribute the degradation to the redox reactions that induce oxygen vacancy complexes during field promoted reduction yet decrease mobile oxygen vacancies while resting, which must be mitigated for the practical applications of ceria-based electrostrictors.