Influence of Nb₂O₅ doped amount on the property of BCTZ lead-free piezoelectric ceramics doped with Li₂CO₃

Ba_0.85Ca_0.15Ti_0.9Zr_0.1O₃ (BCTZ) lead-free piezoelectric ceramics doped with Nb₂O₅ (0.1, 0.3, 0.5, 0.7, 0.9 wt%) and Li₂CO₃ (0.6 wt%) were prepared by conventional solid-state reaction method. Influence of Nb₂O₅ doping amount on the piezoelectric property, dielectric property, phase composition and microstructure of prepared BCTZ lead-free piezoelectric ceramics doped with Li₂CO₃ were investigated by X-ray diffraction and scanning electron microscopy and other analytical methods. The results showed that the sintered temperature decreased greatly when the BCTZ lead-free piezoelectric ceramics were co-doped with Nb₂O₅ and Li₂CO₃; a pure perovskite structure of BCTZ lead-free piezoelectric ceramics co-doped with Nb₂O₅ and Li₂CO₃ sintered at 1,020 °C could be also obtained. The grain size decreased when Nb₂O₅ doping amount increased. The piezoelectric constant (d₃₃), the planar electromechanical coupling factor (k_p), the relative dielectric constant (ε_r) of BCTZ ceramics doped with Li₂CO₃ increased firstly and then decreased, the dielectric loss (tanδ) decreased firstly and then increased when Nb₂O₅ doping amount increased, indicating that Nb₂O₅ was “soft” additive. When Nb₂O₅ doping amount (z) was 0.7 wt% and Li₂CO₃ doping amount was 0.6 wt%, the BCTZ ceramics sintered at 1,020 °C possessed the best piezoelectric property and dielectric property, which d₃₃ was 238 pC/N, k_p was 29.33 %, ε_r was 4,691, tanδ was 2.07 %.