Diffuse characteristics and piezoelectric properties of Tb-doped BCZT ceramics with CaCl2 as sintering aid

Lead-free ceramics 47(Ba0.7Ca0.3)TiO3-0.53Ba(Zr0.2Ti0.8)O3 (BCZT) + 0.2 mol% Tb and xCaCl2 (x = 0.1,0.2 and 0.3 wt%) were prepared at different temperatures (1300, 1350 and 1410 ℃) by solid-state reaction method. The experimental results reveal that dopants can effectively promote the growth of grain at relatively low sintering temperature and CaCl2 as the well sintering aid can produce a pronounced liquid phase to fill the gap between grains sintered at 1410 ℃ with 0.2 wt%. Relative densities and piezoelectric properties of samples can be improved by the introduction of Tb and CaCl2. Comparing with pure BCZT, the residual polarization (Pr) and piezoelectric coefficient (d33*) of ceramics increase from 8.2 to 11.4 μC/cm2 and 568-720 pm/V with 0.2 mol% Tb and 0.2 wt% CaCl2 doped. The enhanced properties of samples may be related to the appearance of liquid phase which can increase relative densities of ceramics to 96% and the form of defect dipole in ceramics. Moreover, introduction of CaCl2 makes dielectric peaks (Tc) move to the high-temperature zone about 13 ℃ and become more and more diffuse (γ = 1.71-1.86), which may have the potential electro-caloric effect application in ferroelectrics.