High energy storage property and breakdown strength of Bi0.5(Na0.82K0.18)0.5TiO3 ceramics modified by (Al0.5Nb0.5)4+ complex-ion

The influence of B-site (Al0.5Nb0.5)4+ complex-ion substitution on the phase transition, microstructure, dielectric, ferroelectric, and energy-storage properties of Bi0.5(Na0.82K0.18)0.5Ti1-x(Al0.5Nb0.5)xO3 (BNKT-xAN) ceramics were systematically investigated. BNKT-xAN ceramics showed single-phase perovskite structure without an obvious phase transition after adding AN. Compact and uniform microstructure with almost the same grain morphology and size was obtained. The AN doping produced slimmer P-E loops and thus improved energy storage property. Meanwhile, the energy storage density increases drastically, and a maximum value of 1.41 J/cm3 at 105 kV/cm was achieved in BNKT-0.08AN through increasing greatly its breakdown strength with more AN content. The temperature dependence of dielectric constant and dielectric loss of BNKT-xAN ceramics illustrated the obvious relaxor phase transition characteristics. Low ionic conductivity and electronic conductivity indicated the BNKT-xAN ceramics have excellent dielectric properties. These results indicated that the BNKT-AN system may be a promising lead-free material for high energy storage density capacitor.