Giant strain performance of lead-free relaxor piezoceramics through synergistic compositional and defect engineering

For applications involving high-precision displacement actuators, piezoceramics exhibiting extensive strain and minimal hysteresis are much sought-after. However, achieving extensive strain concurrent with low hysteresis remains a formidable challenge. We hereby propose an innovative design approach, synergistically harnessing compositional and defect engineering, to concurrently boost the strain response and mitigate hysteresis in (Na_0.5Bi_0.5)TiO₃ (NBT)-based ceramics. The defect dipoles are elaborately designed and introduced into the mixed rhombohedral (R) and tetragonal (T) phases system, which causing reversible domain switching, heightening recoverability of electric-field-induced phase transition and augmenting the electrostrictive effect. The synergy of defect dipoles leading to reversible domain switching and electric field-induced phase transitions is further validated via phase-field simulations. Ultimately, a giant strain of 0.62% with low hysteresis of 10.9% and correspondingly high d₃₃* of 1033 pm V⁻¹ were concurrently realized in the designed NBST(1-x)Mnx (x = 0.3%) specimen. This study opens up a feasible and effective way to design piezoelectric materials with both a giant strain and a narrow hysteresis in lead-free actuator materials.