Direct Visualization of Anti‐Ferroelectric Switching Dynamics via Electrocaloric Imaging

The large electrocaloric coupling in PbZrO3 allows using high‐speed infrared imaging for visualizing anti‐ferroelectric switching dynamics via the associated temperature change. It is found that in ceramic samples of homogeneous temperature and thickness, switching is fast due to the generation of multiple nucleation sites, with devices responding in the millisecond range. By introducing gradients of thickness, however, it is possible to change the dynamics to propagation limited, whereby a single‐phase boundary sweeps across the sample like a cold front, at a speed of ≈20 cm s−1. Additionally, introducing thermostatic temperature differences between two sides of the sample enables the simultaneous generation of a negative electrocaloric effect on one side and a positive one on the other, yielding a Janus‐like electrocaloric response. The negative electrocaloric effect of lead‐zirconate (PbZrO3) is used to observe its anti‐ferroelectric switching dynamics in real time via infrared imaging. Ceramic samples of homogeneous thickness switch via the generation of nucleation sites. By introducing gradients of thickness, however, it is possible to generate a propagation limited process with a phase boundary velocity in the order of 20 cm s−1.