3D simulation of niobium-based ferroelectric materials with precipitation hardening

In this work, we present a thermodynamically consistent, three-dimensional phase field model for ferroelectric ceramics with a particular focus on the niobium-based, lead-free material sodium lithium niobate. The model distinguishes between the crystallographic symmetries of the NaNbO 3 matrix and the LiNbO 3 precipitates by introducing separate energy landscapes for the phase field, thereby restricting the simulated microstructures to physically meaningful domain configurations. We present a novel source/sink approach based on Gaussian functions that allows to model admissible polarization directions in any crystal symmetry. Motivated by experiments, we resolve the interaction between domain walls and plate-like precipitates and compute an anisotropic pinning effect. The proposed framework can be extended towards cyclic loading and more complex precipitate arrangements.