Large strain response in (Mn,Sb)-modified (Bi0.5Na0.5)0.935Ba0.065TiO3 lead-free piezoelectric ceramics

Lead-free piezoelectric ceramics (Bi0.5Na0.5)0.935Ba0.065Ti1-x(Mn0.5Sb0.5)xO3 (BNBT6.5-xMS, x=0.005, 0.010, 0.015, 0.020) were prepared by conventional solid state reaction sintering technique. All ceramics present a pure perovskite phase structure, indicating that (Mn, Sb) has completely diffused into the BNBT6.5 lattice in the studied components. The addition of (Mn, Sb) disrupted the ferroelectric long-range order and promoted the electric field induced strain response. At x=0.015, a large electric field-induced unipolar strain of 0.48% (at an applied electric field of 80 kV/cm) with normalized strain d33*(Smax/Emax) of 602 pm/V are achieved. Temperature dependent measurements of both polarization and strain from room temperature to 120 °C were also studied, and the results suggest that the origin of the large strain is due to a reversible field-induced non-polar relaxor phase to polar ferroelectric phase transformation.