Li-modified Ba0.99Ca0.01Zr0.02Ti0.98O3 lead-free ceramics with highly improved piezoelectricity

In this paper, Ba0.99Ca0.01Zr0.02Ti0.98O3 lead-free ceramics with highly enhanced piezoelectricity have been obtained at an optimized Li+ ion doping content by means of elaborately adjusting the microstructure. The introduction of Li+ ions significantly improves the sinterability due to the emergence of oxygen vacancies and the formation of eutectic liquid phase. The sintering temperature is reduced by 100-150 °C compared with other literatures. The highest piezoelectric coefficient d33 and planar mode electromechanical coupling factor kp can be increased up to 340 pC/N and 44%, which are stem from outstanding ferroelectric activity (Pr = 9.8 μC/cm2, Ec = 220 V/mm) and dielectric property (εr = 2250, tan δ = 1.35%). In addition, the Curie temperature Tc is still maintained about 120 °C. A plausible mechanism concerning the defect dipoles, polarization rotation, and ferroelectric phase transition is constructed in this work to well state above mentioned phenomena.