Ferroelectric and dielectric properties of Sr2−x(Na, K)xBi4Ti5O18 lead-free piezoelectric ceramics

(Na, K)-doped Sr2Bi4Ti5O18 (SBTi) bismuth layer structure ferroelectric ceramics were prepared by the solid-state reaction method. Pure bismuth-layered structural Sr2−x(Na, K)xBi4Ti5O18 (x=0.1, 0.2, 0.3, and 0.4) ceramics with uniform grain size were obtained in this work. The effects of (Na, K)-doping on the dielectric, ferroelectric and piezoelectric properties of SBTi ceramics were investigated. Results showed that (Na, K)-doping caused the Curie temperature of SBTi ceramics to shift to higher temperature and enhanced the ferroelectric and piezoelectric properties. At x=0.2, the ceramics exhibited optimum properties with d33=20 pC/N, Pr=10.3 μC/cm2, and Tc=324 °C.