Antiferroelectric materials are considered as the most promising candidate materials for pulsed power capacitors due to their high breakdown electric field, high saturation polarization, low remanent polarization, and electrical hysteresis. The absence of deep and comprehensive research on antiferroelectric materials still hinders its application. Hence, a further research on antiferroelectric materials is of great importance to promote the development of science and technology and the progress of society.

PbHfO₃ (PHO) is a special antiferroelectric material with a perovskite structure. Its unique double hysteresis loop becomes a research hotspot. PHO has a high recoverable energy density and a great energy efficiency, which can be used to develop high-performance energy storage devices such as supercapacitors and pulse power capacitors. In addition, PHO antiferroelectric materials also have superior electrocaloric effects, which can achieve energy recovery and utilization at different temperatures, thus providing a novel approach for thermal energy utilization and energy conversion. The research of PHO antiferroelectric materials mainly focuses on the crystal structure, phase transition mechanism, energy storage performance (i.e., recoverable energy density, energy efficiency, charge/discharge energy density, etc.), and electrocaloric effect.

There are still many controversies on the crystal structure and phase transition mechanism of PHO. The multiple-phase transition process is rather complex. At present, it is generally believed that PHO has two temperature-induced phase transitions, i.e., the orthogonal symmetry antiferroelectric phase (AFE1) transitions to the intermediate antiferroelectric phase (AFE2) at 433 K, and the AFE2 transitions to the cubic symmetry paraelectric phase at 476 K. However, little work on the intermediate antiferroelectric phase has been reported yet. Some research work was carried out in the energy storage performance of PHO. Ion displacement, lattice distortion, and grain size are the major factors affecting the energy storage performance. As a result, ion doping becomes an effective way to adjust the electrical properties of PHO, thereby improving the energy storage characteristics such as recoverable energy density and energy efficiency, as well as charge and discharge energy density. The performance can be tuned by A-site, B-site, or A/B-site doping since PHO has a perovskite structure. For instance, A-site doping with elements such as Sr, Ba, La, etc. can change the lattice structure and improve the breakdown strength of the system, thus increasing the energy storage performance. B-site doping with Sn, Zr, and Ti can also be used to enhance the antiferroelectricity of the system to achieve a high recoverable energy density. A/B co-doping is also an effective way to improve the energy storage performance of PHO. In addition, the preparation process has a great influence on the crystal structure and energy storage performance of PHO. The rolling process and cold isostatic pressing can reduce the grain size of PHO to achieve the effect of fine crystal reinforcement, which increases its breakdown strength and achieves the excellent recoverable energy density and efficiency. In addition, the electrocaloric effect of PHO-based antiferroelectric materials gives it broad application prospects in electrocaloric refrigeration. At an external electric field, PHO exhibits a polarization reversal to produce a significant thermal effect, thereby achieving efficient refrigeration. The electrocaloric refrigeration method has a higher energy utilization efficiency and a lower power consumption, compared with the conventional mechanical refrigeration method.