The advancement of microelectromechanical systems (MEMS) drives the demand for multifunctional ferroelectrics that synergistically combine substantial strain with competitive energy storage capabilities. In this work, the simultaneous enhancement of electromechanical strain and energy storage properties is achieved in (1−x)(Bi0.5Na0.5)0.94Ba0.06(Ti0.98Mn0.02)O3-xSrTiO3 (0 ≤ x ≤ 0.3) ceramics by synergistically employing A-site defect engineering and the nonergodic/ergodic relaxor (NR/ER) phase boundary design. The incorporation of Sr2+ plays a dual role: it induces cationic disorder that expands the polarization difference (ΔP = Pmax − Pr), thereby effectively boosting the recoverable energy density (Wrec). Concurrently, it stabilizes a critical NR/ER phase ratio near room temperature, which maximizes the strain while minimizing the strain hysteresis. Consequently, when x = 0.15, the optimized system delivers a large strain of 0.45% (d33* = 562 pm/V) with low hysteresis (H = 10.8%). In addition, the x = 0.25 composition exhibits an enhanced Wrec of 1.06 J/cm3, a competitive energy-storage potential (Wrec/E) of 0.013 mC/cm2, and a high efficiency (η) of 81% under 80 kV/cm. This work provides an effective strategy for developing multifunctional lead-free materials for integrated actuators and energy storage devices.
Li et al. (Mon,) studied this question.