Ultra-high strain under low driving field via synergetic design in high-entropy relaxor ceramics

Lead-containing relaxor ferroelectrics are distinguished by outstanding electromechanical properties, making them attractive for applications in modern electrostrictive actuators, piezoelectric transducers, multilayer ceramic capacitors , pyroelectric detectors and many others. Solid solutions of the relaxor–PbTiO 3 systems are of special interest due to the participation of different mechanisms of the energy profile flattening and the related property enhancement, manifesting at various length scales. Here, we report the ultra-high values of the electric field-induced strain under the low driving field ( S > 0.1 % at E = 5 kV/cm) and with negligible hysteresis in the high-entropy relaxor ceramics. The large-signal piezoelectric coefficient d 33 * = S / E = 2050 pm/V is the highest result ever reported in non-textured ceramic systems, and it is comparable with that of the [001]-oriented PbMg 1/3 Nb 2/3 O 3 –PbTiO 3 (PMN-PT) single crystals. The high electromechanical response is associated with a combination of several mechanisms of the energy profile flattening in the ceramic composition, which demonstrates the typical signs of pre-boundary state of crystal structure and properties behavior. The synergetic effect is achieved by the multicomponent system design based on the precise control and tuning of phase boundaries and polar states, as well as enhanced structural disorder via A- and B-site substitution in the parent PMN–PT system. The approach validated in this work is widely applicable to numerous relaxor-based systems for further enhancing their electric field-induced properties not limited to electromechanical response, but also including energy-storage characteristics and electrocaloric effect.