Low sintering temperature and high piezoelectric properties of Li-doped (Ba,Ca)(Ti,Zr)O3 lead-free ceramics

Li-doped Ba0.85Ca0.15Ti0.9Zr0.1O3 (BCZT) lead-free piezoelectric ceramics were prepared by the two-step synthesis and the solid-state reaction method. The density and grain size of ceramics sufficiently increases by Li-doped sintering aid, and their sintering temperature decreases from about 1540 degrees C down to about 1400 degrees C. X-ray diffraction reveals that the phase structure of Li-doped BCTZ ceramics is changed with the sintering temperature, which is consistent with their phase transition observed by the temperature-dependent dielectric curves. The well-poled Li-doped BCZT ceramics show a high piezoelectric constant d(33) (512 pC/N) and a planar electromechanical coupling factor k(p) (0.49), which have the characteristics of soft Pb(Zr,Ti)O-3 (PZT) piezoceramic, on the other hand, the mechanical quality factor Q(m) is about 190, which possesses the features of hard PZT piezoceramics. The enhanced properties of the Li-doped BCZT are explained by the combination of Li-doped effect and sintering effect on the microstructure and the phase transition around room temperature. (C) 2015 Elsevier B.V. All rights reserved.