Dynamic electromechanical behavior of Eu-doped PMN-PZ-PT ceramics: Stress dominance and thermal stability for actuator applications

Piezoelectric actuators are essential components in precision positioning and force generation systems, often operating under complex multiphysics conditions. In this work, soft-type 2.5%Eu-doped 0.52PMN-0.33PT-0.15PZ piezoelectric ceramics with high piezoelectric charge coefficient d 33 = 1030 pC/N and piezoelectric strain coefficient d 33 * = 1120 pm/V were prepared, the electromechanical properties were systematically investigated under varying electric fields, uniaxial mechanical prestresses and temperatures. The results reveal that the strain exhibits a variation of ≈ 50% over the applied mechanical prestress range of 0 - 50 MPa, while showing a variation of < 20% across the tested temperature range 30 - 120°C. This demonstrates that within the tested ranges, mechanical stress is the dominant external factor governing the electromechanical response. With increasing prestress, the strain initially increases—reaching a maximum of 0.150% at 20 MPa—due to stress-assisted non-180° domain switching, and then decreases under higher stress due to domain wall clamping. This behavior reflects a transition from an electric field-controlled regime (< 20 MPa) to a stress-controlled regime (> 20 MPa), where domain wall mobility is suppressed and temperature-dependent phase transition effect is mitigated. Notably, the ceramic achieved a high mechanical work density of 0.040 J/cm 3 with electromechanical conversion efficiency of 46.4% at 40 MPa, while maintaining excellent temperature stability across all prestress conditions. These findings highlight the critical role of domain switching dynamics and stress-temperature coupling in determining actuator behavior, providing valuable design insights for the development of high-performance piezoelectric actuators with improved durability, reliability, and energy efficiency under extreme operational conditions.