An easy and effective strategy to design a composition in the vicinity of triple point for high energy density in dielectric ceramics

The development of high energy density in dielectric ceramics has become one of the most cutting-edge research topics for high pulse power technology applications owing to their high-power density and fast charge/discharge rates. However, dielectric ceramics often shows low energy density owing to the lack of high saturation polarization. Herein, we report a very interesting concept of tricritical/triple point (TCP) which is MPB between rhombohedral, Tetragonal, and Pseudo cubic is very beneficial for the excitement of more extra domains in relaxor ferroelectric ceramics. Since the ceramics are relaxors, domains can be reoriented easily when the field is removed, and very slim P-E loop could be expected to be obtained. Because of the second order (continuous phase transition), the relaxor ferroelectric ceramics maintained their (TCP) in a wide temperature range unlike normal ferroelectric ceramics making them promising for thermal stability. By constructing a triple point in a wide temperature range, high Wrec > 9 j/cm3 with high efficiency of ∼80 %, and the sensitivity factor (ξ = Wrec/E = 179 J/(kV.m2)) was achieved at a moderate electric field <515 kV/cm. Moreover, high-temperature stability up to 160 °C with less than 4–6 % variation in recoverable energy storage density, and working efficiency was also recorded. The reason for high Wrec and their thermal stability in a wide temperature range owes to the (TCP) in a wide temperature range as confirmed by high-quality measurements such as HADAF, XRD, and high-temperature dielectric constant. This study not only focused on achieving high energy storage density but also provides a new strategy for the development of high recoverable energy density in a wide temperature range by utilizing the concept of (TCP).