Influence of Co2O3 doped amount on the properties of (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 lead-free piezoelectric ceramics

The influence of Co₂O₃ doped amount on dielectric and piezoelectric properties of (Ba_0.85Ca_0.15)(Zr_0.1Ti_0.9)O₃ (BCZT) lead-free piezoelectric ceramics was studied by scanning electron microscope(SEM) and X-ray diffraction(XRD) and other analytical methods and conventional solid state method. TiO₂ was chemically pure raw materials, other raw materials were analytical pure raw materials. The results showed that Perovskite structure of BCZT lead-free piezoelectric ceramics did not change when doped with Co₂O₃, the intensity of diffraction peaks of BCZT increased first and then decreased, the grain crystal size of ceramics increased first and then decreased, the density of ceramics increased first and then decreased when Co₂O₃ doped amount increased. The microstructure of ceramics was the best when Co₂O₃ doped amount was 0.40 wt.%. This was also reason for the good piezoelectric properties. The piezoelectric properties(d₃₃, k_p, k_t) of BCZT lead-free piezoelectric ceramics increased first and then decreased, the relative dielectric constant(er) decreased, dielectric loss increased first and then decreased when Co₂O₃ doped amount increased. The comprehensive performance of BCZT lead-free piezoelectric ceramics was optimum when Co₂O₃ doped amount was 0.40 wt.% which piezoelectric strain constant(d₃₃) was 171pC/N, relative dielectric constant(ε_r) was 22400, planar electromechanical coupling coefficient(k_p) was 0.478, dielectric loss was 0.018, electromechanical coupling coefficient of thickness(k_t) was 0.041, sintered temperature was 1340°C.