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

## TL;DR

This paper introduces a new lead-free ceramic material with high electrostrain, low hysteresis, and excellent thermal stability, making it ideal for high-precision actuators.

## Contribution

The study presents a novel B-site doping strategy to achieve synergistic electrostrictive properties in lead-free ceramics.

## Key findings

- Optimal Zr4+ substitution at x = 0.1 yields a high unipolar electrostrain of 0.11% with ultra-low hysteresis.
- The material exhibits a large electrostrictive coefficient of 0.0405 m4/C2 and less than 10% variation in performance from 30–120 °C.
- The enhanced performance is attributed to a transition to a pseudocubic relaxor state with reversible polar nanoregion dynamics.

## Abstract

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.