Regensburg 2019 – wissenschaftliches Programm
MM 5.10: Vortrag
Montag, 1. April 2019, 12:45–13:00, H46
Ferroelectric fracture ratchet effect caused by flexoelectricity — •Kumara Cordero-Edwards1,2, Hoda Kianirad3, Carlota Canalias3, Jordi Sort4,5, and Gustau Catalan1,5 — 1Catalan Institute of Nanoscience and Nanotechnology (ICN2), Barcelona, Catalonia — 2DQMP, University of Geneva, Geneva, Switzerland — 3KTH-Royal Institute of Technology, Stockholm, Sweden — 4Universitat Autònoma de Barcelona (UAB), Bellaterra, Spain — 5Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Catalonia
The propagation front of a crack generates large strain gradients and it is therefore a strong source of gradient-induced polarization (flexoelectricity). Fracture fronts generate flexoelectric fields that have an energy cost which, in turn, affects the mechanical response of materials. In ferroelectrics, this cost depends on the ferroelectric polarity. Therefore one can change the fracture toughness of a ferroelectric by switching its polarization.
Our work demonstrates experimentally that, as a consequence of flexoelectricity, crack propagation is promoted or diminished when directed parallel or antiparallel to the ferroelectric polarization, respectively. In addition, we have studied flexoelectrically induced domain switching around the crack, and showed that crack-induced flexoelectric switching is a contributor to the toughening of ferroelectrics with polarization antiparallel to the crack. The discovery of crack propagation asymmetry implies that fracture physics cannot be assumed to be symmetric in polar materials, and it demonstrates that flexoelectricity must be incorporated in any realistic model.