Ultrahigh storage density achieved with (1-x)KNN-xBZN ceramics

A series of (1-x)K0.5Na0.5NbO3-xBa(Zn1/3Nb2/3)O3 ((1-x)KNN-xBZN) nanostructural ceramics was successfully synthesised via solid-state reactions. These nanostructural ceramics exhibited high energy storage density compared with pure KNN ceramics. Further analysis of their dielectric/ferroelectric properties and structures revealed that the addition of BZN alloy disrupted the long-range order of the ferroelectric lattice of pure KNN and favoured the formation of ferroelectric islands and/or polar nano-regions. Consequently, the nanostructured ceramic with x = 0.05 exhibited ultrahigh energy storage density, W, of approximately 9.14 J/cm3 and recoverable energy storage density, Wrec, of approximately 4.87 J/cm3 under a fairly low applied electrical field (220 kV/cm). These values exceed the highest values ever reported for KNN-based bulk ceramics. In addition, both excellent fatigue endurance (105 cycles) and temperature stability (Δε'/ε100°C < 15 % in the range 30–390 °C) were realised with the 0.97KNN-0.03BZN ceramic. Their excellent energy storage properties render KNN-based ceramics potential candidates for application in pulsed-power systems.