Achieving high energy storage density at low operating fields in lead hafnate-based novel perovskite solid solutions

Miniaturization and integration of pulse power capacitors has become a backbone of modern technology. Antiferroelectric (AFE) perovskite materials with high recoverable energy-storage density (W_rec) at a low operating electric field can meet such a demand. To increase W_rec at low operating voltages, a novel solid solution of (1 − x)PbHfO₃-xAgNbO₃ (0 ≤ x ≤ 0.04) between an AFE and a ferrielectric perovskites is synthesized via a cost-effective solid-state synthesis route. A temperature-composition phase diagram is constructed based on X-ray diffraction, dielectric and ferroelectric measurements. At room temperature, all the compositions are found to crystallize in an orthorhombic symmetry with the Pbam space group and demonstrate AFE properties. Upon heating, the phase transition to another orthorhombic AFE phase with the Imma space group is observed. For the compositions of x ≥ 0.03, a third AFE phase with Imma space group is found. At room temperature an optimal energy-storage performance is obtained at x = 0.027 with W_rec = 4.8 J cm⁻³ and an efficiency of 58% at an electric field of 172 kV cm⁻¹. Such a performance is superior to all the perovskite ceramics so far reported under a similar or lower electric field. Furthermore, all the compositions exhibit good energy storage performance up to temperatures as high as 175 °C, which makes them viable materials for high temperature applications at low operating fields.