Revealing the Giant Electromechanical Effects in Yttria‐Stabilized Zirconia Single Crystal

Ionic conductors exhibiting giant electromechanical responses have emerged as promising alternatives to lead‐based relaxor ferroelectrics for high‐resolution actuators and sensors. However, the role of long‐range oxygen‐vacancy migration in governing electromechanical properties remains unclear and even controversial. Yttria‐stabilized zirconia single crystal (SC‐YSZ) provides an ideal model system to elucidate the origin of electrostriction and piezoelectricity with oxygen‐vacancy migration, owing to the absence of grain boundaries and substrate constraints. Here, atomic force microscopy (AFM) is employed to probe the electromechanical coupling responses of SC‐YSZ, displaying pronounced orientation‐dependent features and non‐intrinsicity in [100]‐, [110]‐, and [111]‐oriented SC‐YSZs. Notably, the giant electrostrictive coefficient | M 33 | of 5.82 × 10 −17 m 2 V −2 and remarkable pseudo‐piezoelectric coefficient | d 33 | of 218 pm V −1 are obtained at the frequency of 10 mHz in [100]‐oriented SC‐YSZ. Local relaxation measurements, macroscopic ionic conductivity, and first‐principles calculations reveal that the orientation‐dependent electrostrictive and pseudo‐piezoelectric responses arise from the long‐range migration of oxygen vacancies, governed by direction‐dependent migration difficulty under electric fields. This work provides direct evidence linking giant electromechanical responses with long‐range oxygen‐vacancy migration, and highlights that such effects in SC‐YSZ cannot be neglected when employed as substrates or composite layers in electroactive materials and device systems.