Giant overall energy density performances via introducing aliovalent cations in BNT-based ferroelectric ceramics

Abstract

The strategy of introducing aliovalent cations in the ferroelectric perovskites is the most promising for obtaining excellent overall energy storage density performances, simultaneously with good efficiency and thermal stability in dielectric ceramics for high pulse power technologies. Aliovalent cations could greatly enhance the short-range ferroelectric order (Polar nanoregions, PNRs), and local random field caused by vacancies, mismatch between size, electronic configuration, and other physical and chemical properties of aliovalent cations with the host perovskite. PNRs and local random field make the ceramic relaxor like with excellent overall energy storage density results such as total energy storage density (WT = 10.55 J/cm3, recoverable energy storage density Wrec = 7.82 J/cm3), power density (PD = 197 MW/cm3), current density (CD = 1312 A/cm2), and ultra-fast discharge rate (t = 24 ns) simultaneously with good working efficiency of 74 % by introducing 14 mol% of Bi(Zn1/3Nb2/3) aliovalent cations in the morphotropic phase boundary (MPB) (Bi0.47Na0.47)TiO3–0.06BaTiO3 composition. In addition, the same optimum sample also showed good thermal stability up to 240 °C, with <10–13 % variation in recoverable energy storage density and working efficiency respectively. The reason of excellent overall energy storage density, and their thermal stability in a broad temperature range might be due to short-range ferroelectric order, local random field, relaxor ferroelectric polymorphic phases, highly dense microstructure with small and uniform grains, as well as large band gape. Our study provides a good clue to obtain giant overall energy density results with good working efficiency and thermal stability in relaxor ferroelectric ceramics for high pulse power technology.