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Enabling flexoelectric engineering through modeling and computation

Periodic Reporting for period 2 - FLEXOCOMP (Enabling flexoelectric engineering through modeling and computation)

Reporting period: 2018-03-01 to 2019-08-31

In our everyday life, we use devices that transform electrical energy into mechanical energy and vice-versa. This energy conversion happens in sensors, actuators and energy-harvesters. Most of these devices rely now on piezoelectric materials, which nevertheless are brittle, expensive, and non-biocompatible. For these reasons, there is a need to develop new materials for electro-mechanical transduction. Flexoelectricity is a related but different effect, by which electric polarization is coupled to strain gradients, i.e. it requires inhomogeneous deformation. Strain gradients develop when we bend or twist a thin wire. Flexoelectricity is present in a much wider variety of materials, including non-polar dielectrics and polymers, but is only significant at small length-scales, where high strain-gradients develop. It has been suggested that flexoelectricity could enable piezoelectric metamaterials made out of non-piezoelectric components, including soft materials. This would significantly broaden the class of materials used for electro-mechanical transduction, which could enable affordable, biocompatible and self-powered small-scale devices. However, our understanding of the fundamental origin of flexoelectricity or of how to exploit it in practice is very poor. OThe objective of this project is to develop an advanced computational infrastructure to quantify flexoelectricity in solids, focusing on continuum models but also exploring multiscale aspects, in tight collaboration with experiment. We plan to explore the effects of strain gradients on the physics of dielectrics, identifying fundamental manifestations and extracting the underlying engineering principles for a new generation of electromechanical metamaterials.
We have developed a flexible computational infrastructure that is able to incorporate the flexoelectric effect in electromechanical simulations. With this infrastructure we have explored fundamental manifestations of flexoelectricity in fracture of dielectrics and in ferroelectric materials, and we have explored design concepts for electromechanical metamaterials.
We will develop new theories and computational methods to understand flexoelectricity, ranging from the atoms to the devices. We will develop concepts for new materials that efficiently exploit flexoelectricity.