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. 
B. Khanbabaee, E. Mehner, C. Richter, J. Hanzig, M. Zschornak, U.   Pietsch, H. St\"ocker, T. Leisegang, D. C. Meyer, and S....
cond-mat.mtrl-sci