Piezoelectric and dielectric properties of Dy2O3-doped (Bi0.5Na0.5)0.94Ba0.06TiO3 lead-free ceramics

(Bi0.5Na0.5)0.94Ba0.06TiO3 + x wt% Dy2O3 with x = 0–0.3 ceramics were synthesized by conventional solid-state processes. The effects of Dy2O3 on the microstructure, the piezoelectric and dielectric properties were investigated. X-ray diffraction pattern confirmed that the coexistence of tetragonal and rhombohedral phases in the (Bi0.5Na0.5)0.94Ba0.06TiO3 composition was not changed by adding 0.05–0.3 wt% Dy2O3. SEM images indicate that all the ceramics have pore-free microstructures with high density, and that doping of Dy2O3 inhibits the grain growth of the ceramics. The addition of Dy2O3 shows the double effects on decreasing the piezoelectric and dielectric properties for 0 < x < 0.15 when Dy3+ ions substitute B-site Ti4+ ions, and increasing the properties for 0.15 < x < 0.3 when Dy3+ ions enters into A-site of the perovskite structure. The optimum electric properties of piezoelectric constant d33 = 170 pC/N and the dielectric constant ɛr = 1900 (at a frequency of 1 kHz) are obtained at x = 0.3.

Research highlights▶ (Bi0.5Na0.5)0.94Ba0.06TiO3 ceramics remain pure perovskite structure by adding Dy2O3. ▶ Dy2O3 inhibits the grain growth of the ceramics. ▶ Dy2O3 shows the double effects on electric properties of the ceramics. ▶ Substitution content of Dy2O3 tailors the electric properties of the BNBT ceramics.