Laurent Guin (ETH Zurich) A phase-field model for ferroelectrics with general kinetics
Ferroelectric ceramics are a prime example of multifunctional materials for which mechanical and electrical properties are intrinsically coupled. They exhibit a spontaneous electric polarization that can be reversed under the application of an electrical or mechanical loading. The macroscopic features of polarization switching derive from mesoscale processes, which consist of the nucleation and growth of domains of constant polarization. These domains, separated by domain walls, correspond to the different orientations of the crystallographic phase (e.g., the three orientations of the tetragonal phase in BaTiO3). Simulations of the evolution of polarization domains at the mesoscale use diffuse-interface models where the electro-mechanical fields evolve steeply but continuously in the domain walls. Existing diffuse-interface models are based on the Allen-Cahn equation which assumes, unlike experimental evidence, a linear relation between the velocity of domain walls and their conjugate driving force. In this work, we develop an alternative phase-field formulation that accounts for the non-linear kinetics of domain walls. The behavior of this model is interpreted as the regularization of a sharp-interface model with an arbitrary kinetics.
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- 2021-01-19 14:00