Artificial piezoelectricity in centrosymmetric SrTiO3

Defect engineering is an effective and powerful tool to control existing material properties and create completely new ones, which are symmetry-forbidden in a defect-free crystal. This letter reports on the creation of piezoelectrically active near-surface layer of centrosymmetric SrTiO3, modified by the electric field-induced migration of oxygen vacancies. We provide the unequivocal proof of piezoelectricity through the stroboscopic time-resolved X-ray diffraction under alternating electric field. The magnitude of the discovered piezoelectric effect is comparable with the bulk piezoelectric effect in commercial ferroelectric materials. Such artificially formed defect-mediated piezoelectricity can be important as an alternative road for smart materials design.