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)(0.94)Ba0.06TiO3 (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 (d(33) = 170 pC/N), higher mechanical quality factor (Q(m) = 102), high relative dielectric constant (epsilon(r) = 1611) and lower dissipation factor (tan delta = 0.051) at a frequency of 10 kHz. The BNBT6 ceramics doped with 0.4 wt.% Dy2O3 have the highest planar coupling factor (k(p) =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.%. (c) 2010 Elsevier B.V. All rights reserved.