Electromechanical dopant-defect interaction in acceptor-doped ceria

Oxygen defective cerium oxide CeO_2−δ exhibits a non-classical giant electromechanical response that is superior to that of lead-based electrostrictors. In this work, we report the key-role of acceptor dopants, with different size and valence (Mg²⁺, Sc³⁺, Gd³⁺, and La³⁺), on polycrystalline bulk ceria. Different dopants tune the electrostrictive properties by changing the electrosteric dopant–defect interactions. We find two distinct electromechanical behaviors: when the interaction is weak (dopant-vacancy binding energy ≤0.3 eV), electrostriction displays a high coefficient (M₃₃), up to 10⁻¹⁷ (m V⁻¹)², with strongly time-dependent effects. In contrast, we observe no time-dependent effects when the interaction becomes strong (≥0.6 eV).