Direct Observation of Huge Flexoelectric Polarization around Crack Tips.
Wang, Hongguang;Jiang, Xijie;Wang, Yi;Stark, Robert W;van Aken, Peter A;Mannhart, Jochen;Boschker, Hans;
Nano letters2020Vol. 20pp. 88-94
211
wang2020directnano
Abstract
Flexoelectricity is especially relevant for nanoscale structures, and it is expected to be largest at the tip of cracks. We demonstrate the presence of a huge flexoelectric polarization at crack tips in SrTiO by direct observation with scanning transmission electron microscopy. We observe an averaged polarization of 62 ± 16 μC cm in the three unit cells adjacent to the crack tip, which is one of the largest flexoelectric polarizations ever reported. The polarization is screened by an electron density of 0.7 ± 0.1 e/uc localized within one unit cell. These findings reveal the relevance of flexoelectricity for the science of crack formation and propagation.