Piezoresponse force microscopy (PFM) is an indispensable tool in the investigation of local electromechanical responses and polarization switching. The acquired data provide spatial information on the local disparity of polarization switching and electromechanical responses, making this technique advantageous over macroscopic approaches. Despite its widespread application in ferroelectrics, it has rarely been used to investigate the ferrielectric (FiE) behaviors in antiferroelectric (AFE) materials. Herein, the PFM was utilized to study the local electromechanical behavior and distribution of FiE, and the AFE phases of PbZrO₃ thin-film were studied, where only the FiE behavior is observable using a macroscopic approach. The FiE region resembles a ferroelectric material at low voltages but exhibits a unique on-field amplitude response at high voltages. In contrast, the AFE region only yields an observable response at high voltages. Phase-field simulations reveal the coexistence of AFE and FiE states as well as the phase-transition processes that underpin our experimental observations. Our work illustrates the usefulness of PFM as an analytical tool to characterize AFE/FiE materials and their phase-coexistence behavior, thereby providing insights to guide property modification and potential applications.

Dielectric composites boost the family of energy storage and conversion materials as they can take full advantage of both the matrix and filler. This review aims at summarizing the recent progress in developing high-performance polymer- and ceramic-based dielectric composites, and emphases are placed on capacitive energy storage and harvesting, solid-state cooling, temperature stability, electromechanical energy interconversion, and high-power applications. Emerging fabrication techniques of dielectric composites such as 3D printing, electrospinning, and cold sintering are addressed, following by highlighted challenges and future research opportunities. The advantages and limitations of the typical theoretical calculation methods, such as finite-element, phase-field model, and machine learning methods, for designing high-performance dielectric composites are discussed. This review is concluded by providing a brief perspective on the future development of composite dielectrics toward energy and electronic devices.