Effects of Li2CO3–CuO addition on the sintering behavior, dielectric and piezoelectric properties of PZT ceramics

The influences of CuOLi 2 CO 3 additive on the sintering behaviors, microstructure, and dielectric/piezoelectric/ferroelectric properties of a commercial "soft" lead zirconate titanate (PZT)-based piezoelectric ceramic have been investigated in this paper. The sintering temperature of PZT ceramic could be successfully reduced to 1050 °C with the addition of 0.1 wt% CuOLi 2 CO 3 . The possible sintering mechanism and sintering kinetics were studied based on the in situ measurement of temperature dependent sintering shrinkages of the samples. Some Cu/Li ions incorporated into the perovskite lattice and the remainder precipitated as Pb-rich secondary phase by eutectic formation at triple junction of grain boundaries. Cu + seems to be more likely to enter into the perovskite lattice in comparison to Cu 2+ , leading to a little smaller ε r , tan δ , d 33 and high temperature conduction . The addition of CuOLi 2 CO 3 leads to an increase in the concentration of rhombohedral phase around the morphotropic phase boundary (MPB) composition, resulting in decreases in permittivity, dielectric loss, piezoelectric coefficient ( d 33 ) , and coercive field ( E c ), slight increase in remnant polarization ( P r ), while little change in T c temperature (~ 310 °C) and electromechanical coupling coefficient ( k p ). Good combined dielectric and piezoelectric properties with ε r = 1881, tan δ = 1.32%, d 33 = 474 pC/N and k p = 0.73 could be obtained with the addition of 0.4 wt% CuOLi 2 CO 3 after sintering at 1050 °C/2 h.