Ultra-low hysteresis electric field-induced strain with high electrostrictive coefficient in lead-free Ba(Zr_xTi_1-x)O₃ ferroelectrics

From the application point of view, high electric field-induced strain with ultra-low hysteresis or hysteresis-free characteristic is highly desired in high-precision displacement actuators. In this work, lead-free Ba(Zr_xTi_1-x)O₃ (BZT) ferroelectrics with x in the range between 0.02 and 0.1 were fabricated by a conventional solid state reaction method. The structural evolution and electrical properties were investigated systematically with an emphasis on electrostrictive effect. As x increases from 0.02 to 0.1, the crystal lattice parameters (a and c axes) increase while the tetragonality (c/a-1) goes down. In addition, the Curie temperature (T_C) of BZT decreases gradually, while the temperatures corresponding to tetragonal-to-orthorhombic (T-O) and orthorhombic-to-rhombohedral (O-R) phase transitions increase. Ultra-low hysteresis (<8%) and high electric field-induced strains (>0.15% at 60 kV/cm) are observed in all studied compositions. Most importantly, a high longitudinal electrostrictive coefficient Q₃₃ (0.0453 m⁴/C²) was also identified in x = 0.1 composition. This work not only reports high electric field-induced strains with ultra-low hysteresis and high Q₃₃ in lead-free BZT ferroelectrics, but also indicates a potential application for BZT ceramics in high-precision displacement actuators.