A (Ba_0.94Ca_0.06)(Ti_0.95Zr_0.05)O₃ ceramic sheet doping to improve the inverse piezoelectric effect of the poly (vinylidene fluoride‐trifluoroethylene)‐based composite film

Abstract A lead‐free tetragonal‐phase (Ba_0.94Ca_0.06)(Ti_0.95Zr_0.05)O₃ (BCTZ) micro sheet is prepared by molten‐salt growth method, which exhibits a polarizing behavior of relaxor ferroelectricity and possesses a high dielectric constant (ε_r) of ~2400. Subsequently, the BCTZ sheet is evenly doped into ferroelectric copolymer P(VDF‐TrFE)55/45 mol% with different mass fractions, and the flexible BCTZ/P(VDF‐TrFE) composite films are prepared using a conventional solution casting process. ε_r of BCTZ/P(VDF‐TrFE) increases with the mass content of BCTZ, and reaches 23.8 in 20 wt% BCTZ sample. Meanwhile, at a high electrical field of 30 MV/m, the strain and electric field of BCTZ/P(VDF‐TrFE) are in the opposite direction, indicating a negative value of piezoelectric strain coefficient (d₃₃) caused by inverse piezoelectric effect. In addition, d₃₃ of different BCTZ/P(VDF‐TrFE) films are fitted using a strain‐electrical field curve, which firstly increases and then decreases with increases in BCTZ content. As such, a high d₃₃ of −47.3 pC/N is obtained in BCTZ/P(VDF‐TrFE)15/85 wt% film. Thus, this research concerning the inverse piezoelectric effect may provide a reference for designing a piezoelectric composite using in transducers and actuators.