abstract
SrTiO3 ceramics are investigated by piezoresponse force microscopy. Piezoelectric contrast is observed on polished surfaces in both vertical and lateral regimes and depends on the grain orientation varying in both sign (polarization direction) and amplitude. The observed contrast is attested to the surface piezoelectricity due to the flexoelectric effect (strain gradient-induced polarization) caused by the surface relaxation. The estimated flexoelectric coefficient is approximately one order of magnitude smaller as compared to that recently measured in SrTiO3 single crystals. The observed enhancement of piezoresponse signal at the grain boundaries is explained by the dipole moments associated with inhomogeneous distribution of oxygen vacancies.
keywords
NANOGRAIN CERAMICS; GRAIN-BOUNDARIES; RAMAN RESPONSE
subject category
Physics
authors
Kholkin, A; Bdikin, I; Ostapchuk, T; Petzelt, J
our authors
Andrei Kholkin
Research Coordinatoracknowledgements
The authors wish to thank Portuguese Foundation for Science and Technology (Project No. PTDC/FIS/81442/2006) for the financial support. This work was also supported by the Grant Agency of the Czech Republic (Project No. 202/06/P219) and Czech Academy of Sciences (Project No. AVOZ 10100520). Collaboration with Scientec within joint Agilent-CICECO PFM laboratory and intensive discussions with Professor Alexander Tagantsev are highly appreciated.