A (Ba0.94Ca0.06)(Ti0.95Zr0.05)O3 ceramic sheet doping to improve the inverse piezoelectric effect of the poly (vinylidene fluoride-trifluoroethylene)-based composite film

A lead-free tetragonal-phase (Ba 0.94 Ca 0.06 )(Ti 0.95 Zr 0.05 )O 3 (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 ( d 33 ) caused by inverse piezoelectric effect. In addition, d 33 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 d 33 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.