Composition-Driven Ultra-Low Hysteresis Electrostrictive Strain in BaTiO3-BaZrO3-Bi(Zn2/3Nb1/3)O3 Ceramics with High Thermal Stability

High electrostrain, excellent thermal stability, and low hysteresis are critical requirements for advanced high-precision actuators. However, simultaneously achieving these synergistic properties in lead-free ferroelectric ceramics remains a significant challenge. In this work, a targeted B-site doping strategy was employed to develop novel lead-free (0.99-x)BaTiO3-xBaZrO3-0.01Bi(Zn2/3Nb1/3)O3 (BT-xBZ-BZN, x = 0–0.2) ceramics. Systematic investigation identified optimal Zr4+ substitution at x = 0.1, which yielded an outstanding combination of electromechanical properties. For this optimal composition, a high unipolar electrostrain (Smax = 0.11%) was achieved at 50 kV/cm, accompanied by an ultra-low hysteresis (HS = 1.9%). Concurrently, a large electrostrictive coefficient (Q33 = 0.0405 m4/C2) was determined, demonstrating excellent thermal robustness with less than 10% variation across a broad temperature range of 30–120 °C. This superior comprehensive performance is attributed to a composition-driven evolution from a long-range ferroelectric to a pseudocubic relaxor state. In this state, the dominant electrostrictive effect, propelled by reversible dynamics of polar nanoregions (PNRs), minimizes irreversible domain switching. These findings not only present BT-xBZ-BZN (x = 0.1) as a highly promising lead-free candidate for high-precision, low-loss actuator devices, but also provide a viable design strategy for developing high-performance electrostrictive materials with synergistic large strain and superior thermal stability.