• • The optimized composition x = 0.015 delivers an electrostrain of ~0.52% with a nearly symmetric bipolar S–E response and d*33 ≈ 867 pm/V, directly addressing the strain–symmetry trade-off that limits actuator precision in lead-free systems.
• • At x = 0.025, the electrostrictive coefficient reaches ~0.055 m4/C2, indicating a shift toward electrostriction-dominated behavior that reduces hysteresis and improves positioning accuracy for high-cycle actuator applications.
• • Zr-induced lattice softening and R3c–P4bm phase coexistence flatten the free-energy landscape, enabling reversible field-driven polarization dynamics; this mechanism suppresses irreversible domain-wall motion, as evidenced by reduced remanent polarization and coercive field.
• • The electromechanically optimized composition exhibits noncytotoxic behavior and preliminary surface mineral deposition in simulated body fluid (SBF), supporting biofunctional potential for implantable or biomedical devices where lead-free compliance is mandatory.