Antiferroelectric behavior and giant strain in BNKT ceramics complex Cs2Nb4O11 tungsten bronze phase

BNT-based ceramics are very attractive for the electrical energy storage and electric field-induced strain. However, the reported BNT-based ceramics are usually the perovskite solid solution. In this work, the super adjustability of Cs2Nb4O11 antiferroelectric phase for lead-free (1-x)Bi0.5(Na0.82K0.18)0.5TiO3-xCs2Nb4O11 ceramics with complex-phase are carefully studied. The Bi0.5(Na0.82K0.18)0.5TiO3 ceramics modified by a trace of Cs2Nb4O11 component suddenly transform to antiferroelectric phase from typical ferroelectric. A giant strain of 0.48% and a d33* of 600 pm/V are obtained originating from a reversible transition between antiferroelectric and ferroelectric states. And a high energy density of 1.0 J/cm3 is also achieved by reversible phase transitions. Therefore, the composite ceramics by designing tungsten bronze and perovskite complex phase illustrate great potential for actuator or energy storage applications.