Diffusional dynamic process of irreversible ferroelectric to antiferroelectric phase transition and the rate limit

The ferroelectric to antiferroelectric phase transition in perovskite structures and its underlying mechanism form the physical foundation for numerous applications such as high-performance energy storage, ultrafast information storage, and electrocaloric refrigeration. Understanding of ferroelectric to antiferroelectric phase transition, especially the description of the transition dynamic process, is crucial for material design and device reliability enhancement. Most of the previous studies demonstrated that ferroelectric to antiferroelectric phase transition are first-order transitions driven by atomic rearrangement, generally regarded as prototypical fast kinetic processes. Here, we report an irreversible ferroelectric to antiferroelectric phase transition at low temperatures in Pb(Zr_0.97Ti_0.03)O₃ as seen by neutron diffraction patterns. The in-situ variable-temperature transmission electron microscopy reveals that the ferroelectric to antiferroelectric phase transition exhibits relaxation behavior and is a slow diffusional dynamic process, which corrects the previous understanding. Density functional theory simulations reveals that the irreversible transition behavior is due to variation of the transition energy barrier with temperature. Based on Density functional theory and experimental data, a multiscale phase-field model was developed to describe the transition dynamics and provide the theory limitation for the rate of ferroelectric to antiferroelectric phase transition in Pb(Zr_0.97Ti_0.03)O₃ at low temperatures, offering a physical basis for future material applications and device design.