Influence of Co Ion Doped Amount on Property of BCTZ Piezoelectric Ceramics Sintered at Low Temperature

Abstract

Ba_0.85Ca_0.15Ti_0.9Zr_0.1O₃ (abbreviated as BCTZ) lead-free piezoelectric ceramics co-doped with Li₂CO₃(0.6 wt.%) and different Co ion content (x = 0, 0.25, 0.4, 0.6, 0.8 wt.%) were prepared by conventional solid state reaction method. Influence of Co ion doped amount on the phase structure, microstructure, piezoelectric properties and dielectric properties of prepared BCTZ piezoelectric ceramics doped with Li₂CO₃ were investigated by scanning electron microscope (SEM), X-ray diffraction (XRD) and other analytical methods. The results show that Co²⁺ and Co³⁺ instead of Zr⁴⁺ did not change the crystal structure and all the BCTZ piezoelectric ceramics possessed single phase perovskite structure with orthorhombic symmetry when Co ion doped amount was less than 0.6 wt.%. When Co ion doped amount was 0.8 wt.%, impurity phase appeared in the ceramics. The piezoelectric constant(d₃₃), planar electromechanical coupling coefficient (kp), the dielectric constant (ϵ_r) and the relative density of BCTZ ceramics increased first and then decreased, the dielectric loss (tanδ) of BCTZ ceramics decreased first and then increased at the same time, the optimize sintered temperature (t_s) decreased while Co ion doped amount increased. The influence of Co ion doped amount on the properties of BCTZ ceramics doped with Li₂CO₃ were caused by lattice distortion and “hard effect” piezoelectric additive. The BCTZ ceramics had the optimum properties, which d₃₃ was 316 pC/N, tanδ was 0.021, k_p was 0.43, ϵ_r was 3209, the sintered temperature was 1010°C, the relative density was 99%, while Co ion doped amount was 0.60 wt.% and Li₂CO₃ doped amount was 0.6 wt.%.

Keywords:

• Piezoelectric ceramics
• Co ion
• lead-free piezoelectric ceramics; barium calcium zirconate and titanate; piezoelectric properties

Funding

The work was supported by Program of Science and Technology Support of Jiangsu Province (No. BE2008029). The work was supported by Project of Combination of Producing, Learning and Studying of Guangdong Province and Education Department (No. 2011B090400027).