Structure, Antiferroelectricity and Energy-Storage Performance of Lead Hafnate in a Wide Temperature Range.

Lead hafnate (PbHfO) has attracted a lot of renewed interest due to its potential as antiferroelectric (AFE) material for energy storage. However, its room temperature (RT) energy-storage performance has not been well established and no reports on the energy-storage feature of its high-temperature intermediate phase (IM) are available. In this work, high-quality PbHfO ceramics were prepared via the solid-state synthesis route. Based on high-temperature X-ray diffraction data, the IM of PbHfO was found to be orthorhombic, Imma space group, with antiparallel alignment of Pb ions along the [001] directions. The polarization-electric field (P-E) relation of PbHfO is displayed at RT as well as in the temperature range of the IM. A typical AFE loop revealed an optimal recoverable energy-storage density () of 2.7 J/cm, which is 286% higher than the reported data with an efficiency (η) of 65% at 235 kV/cm at RT. A relatively high value of 0.7 J/cm was found at 190 °C with an η of 89% at 65 kV/cm. These results demonstrate that PbHfO is a prototypical AFE from RT up to 200 °C, making it a suitable material for energy-storage applications in a wide temperature range.