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 BaTiO3 at room temperature, this range spans from 0.1 to 50 nm, a typical thickness range for epitaxial ferroelectric thin films.Fil: Abdollahi, Amir. Universidad Politécnica de Catalunya; EspañaFil: Peco Regales, Christian. Universidad Politécnica de Catalunya; EspañaFil: Millán, Raúl Daniel. Universidad Politécnica de Catalunya; España. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Arroyo Balaguer, Marino. Universidad Politécnica de Catalunya; EspañaFil: Catalan, Gustau. Institut Catalá de Recerca I Estudis Avançats; España. Institut Catala de Nanociéncia i Nanotecnologia; EspañaFil: Arias, Irene. Universidad Politécnica de Catalunya; España. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
