Electromechanical coupling in alkaline-earth doped-ceria ceramics

Oxygen-deficient cerium oxide ceramics exhibit an anomalously high electromechanical response called giant electrostriction. This feature has been linked to the polarization and reorganization of ionic defects, i.e., V O · · , under an electric field. However, the exact mechanism and how it is related to intrinsic/extrinsic characteristics of doped ceria remains unclear. The present work investigates how alkaline-earth dopants with different defect–dopant interactions affect the overall electrochemical properties and defect chemistry and, ultimately, how these features impact the final electromechanical properties. We found higher dopant–defect associations attenuate the low-frequency relaxation of the electrostrictive coefficient. The defect chemistry is shown to be the main factor controlling the final electromechanical properties rather than defect concentration. All compositions show a similar electrostrictive response at high frequencies, indicating a common underlying mechanism. All samples showed a high electrostrictive coefficient (up to 3·10 −17 m 2 /V 2 ) and pseudo-piezoelectric response (32 pm/V).