Effect of flexoelectricity in fracture of ferroelectrics.
27 June, 2019 @ 10:00 am - 11:00 pm
Jordi Barceló received the Bachelor’s degree in Mathematics and Physic’s Engineering and the Master in Advanced Mathematics and Mathematical Engineering from Facultat de Matemàtiques i Estadística (UPC) in 2017 and 2018, respectively, with a CFIS fellowship. From March 2018, he is a PhD candidate at LaCàN research group, where she focuses on the simulation of flexoelectricity, ferroelectrics and crack propagation.
Ferroelectrics are widely used for many applications thanks to their rich phenomenology, in particular (1) their spontaneous polarization and ability to switch between different crystallographically equivalent variants forming typical ferroelectric domain microstructure, and (2) the highly non-linear electromechanical coupling resulting in large sensing and actuation capabilities, clearly surpassing those of linear piezoelectrics. The boundaries between ferroelectric domains with different crystallographic orientation and thus polarization are called domain walls and have thicknesses in the nanometer range. They are sources of large strain and polarization gradients, and consequently will exhibit a flexoelectric response. Flexoelectricity is the coupling between polarization and strain gradients, and conversely strain and polarization gradient. It is universal, as it is allowed in any dielectric, irrespective of its symmetry, and small scale, as it requires large strain gradients for a significant effect. Furthermore, flexoelectricity may play a role also in the reduced toughness of ferroelectric domain walls, which have been observed to provide preferred paths for crack propagation.