Revision as of 11:10, 27 February 2020

Abstract

Cracks generate the largest strain gradients that any material can withstand. Flexoelectricity (coupling between strain gradient and polarization) must therefore play an important role in fracture physics. Here we use a self-consistent continuum model to evidence two consequences of flexoelectricity in fracture: the resistance to fracture increases as structural size decreases, and it becomes asymmetric with respect to the sign of polarization. The latter phenomenon manifests itself in a range of intermediate sizes where piezo- and flexoelectricity compete. In ${\displaystyle BaTiO_{3}}$ at room temperature, this range spans from ${\displaystyle 0.1}$to${\displaystyle 50nm}$, a typical thickness range for epitaxial ferroelectric thin films.