High strain and energy-storage density across a wide temperature range in fine PbHfO3 ceramics

Antiferroelectric materials exhibit fantastic application potential in multifunctional devices due to their special structure and polarization/strain-electric field responses. However, it has long been challenging to realize multifunctionality in PbHfO3, one of the prototypical antiferroelectrics, due to its poor sinterability and structural complexity. To address these issues, we report an effective strategy to obtain fine and dense PbHfO3 ceramics by the solid-state reaction method involving a liquid phase sintering mechanism. The crystal structure, microstructure, phase transitions, energy storage, and strain performance are systematically investigated. A high recoverable energy density Wreco (7.29 J/cm3) and a large strain (0.51%) are achieved with a temperature-stable (25 ∼ 175 °C) feature. By combination of synchrotron and laboratorial X-ray diffraction, Raman spectroscopy, dielectric and impedance spectroscopy, and density-functional-theory calculations, the high and temperature-stable energy-storage and strain properties are determined to arise from the stable antiferroelectric nature of PbHfO3 with a large polarization in a broad temperature range and its transformation to a ferroelectric phase with R3c symmetry under electric field. Furthermore, the ceramics present a negative temperature coefficient of resistance in a higher temperature range of 400 ∼ 600 °C. These performances grant PbHfO3 antiferroelectric ceramics a huge potential for applications in high-density energy storage capacitors, large-displacement actuators, and temperature sensors and compensators over a broad temperature range.