Effect of Dy2O3 on the structure and electrical properties of (Bi0.5Na0.5)0.94Ba0.06TiO3 lead-free piezoelectric ceramics

Dy2O3 (0–0.8 wt.%)-doped (Bi0.5Na0.5)0.94Ba0.06TiO3 (abbreviated as BNBT6) lead-free piezoelectric ceramics were synthesized by conventional solid-state processes. The compositional dependence of phase structure and electrical properties of the ceramics was studied. X-ray diffraction (XRD) data shows that 0.2–0.8 wt.% Dy2O3 can diffuse into the lattice of BNBT6 ceramics and forms a pure perovskite phase. SEM images indicate that all the modified ceramics have a clear grain boundary and a uniformly distributed grain size, and the BNBT6 ceramics doped with appropriate Dy2O3 become denser. At room temperature, the ceramics doped with 0.6 wt.% Dy2O3 have the highest piezoelectric constant (d33 = 170 pC/N), higher mechanical quality factor (Qm = 102), high relative dielectric constant (ɛr = 1611) and lower dissipation factor (tan δ = 0.051) at a frequency of 10 kHz. The BNBT6 ceramics doped with 0.4 wt.% Dy2O3 have the highest planar coupling factor (kp = 0.33). Moreover, all BNBT6-x (wt.%) Dy2O3 ceramics exhibit a typical relaxor behavior with diffuse phase transition characteristics and the degree of ferroelectric relaxation behavior attains peak value at doping level of 0.4 wt.%.

Research highlights▶ In this work, Dy2O3-doped (Bi0.5Na0.5)0.94Ba0.06TiO3 (BNBT6) ceramics were designed and prepared. ▶ Enhanced piezoelectric properties were obtained in the Dy2O3 doped BNBT6 ceramics, at room temperature, the ceramics doped with 0.6 wt.% Dy2O3 have the highest piezoelectric constant (d33 = 170 pC/N), higher mechanical quality factor (Qm = 102), high relative dielectric constant (ɛr = 1611) and lower dissipation factor (tan δ = 0.051) at a frequency of 10 kHz. ▶ The BNBT6 ceramics doped with 0.4 wt.% Dy2O3 have the highest planar coupling factor (kp = 0.33).