Berlin 2018 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 60: Topical session (Symposium EPS and MM): Mechanical Properties at Small Scales
MM 60.3: Talk
Thursday, March 15, 2018, 16:15–16:45, H 0106
Influence of flexoelectricity on nanomechanical properties of ferroelectrics — •Gustau Catalan1, Kumara Cordero-Edwards2, Fabian Vasquez-Sanchez2, Amir Abdollahi3, and Neus Domingo2 — 1ICREA-Institucio Catalana de Recerca i Estudis Avançats, Barcelona, Catalonia — 2ICN2-Institut Catala de Nanociencia i Nanotecnologia, Barcelona, Catalonia — 3Universitat Politecnica de Catalunya (UPC), Barcelona, Catalonia
Flexoelectricty is a coupling between strain gradients (inhomogeneous deformations) and electric polarization. It is allowed by symmetry in all materials, but it is strongest in those with high dielectric constants, such as ferroelectrics. Because of flexoelectricity, the electrostatic energy cost of very inhomogeneous deformations, such as those that can be induced at the nanoscale due to e.g. nanoindentation or cracking, can be enormous. Flexoelectricity thus has a strong impact on the mechanical response of materials (and particularly ferroelectrics ) at the nanoscale.
Here I will present results that have profound implications for our understanding of solid state mechanics and fracture physics. Specifically, due to flexoelectricity the indentation response and also the fracture propagation in ferroelectrics can be asymmetric: cracks travelling parallel to the ferroelectric polarization become much longer than tose travelling against it. This discovery challenges the general notion that mechanical properties of matter are symmetric with respect to space inversion. Some implications and possible applications of this discovery will be discussed.