Phase structure regulation and enhanced piezoelectric properties of Li-doped KNN-based ceramics

Abstract 0.96(K0.48Na0.52-xLix)NbO3-0.04Bi0.5Na0.5ZrO3 (KNLxN-BNZ) lead-free ceramics have been synthesized by traditional solid-state reaction. Here, the relationship between phase composition and piezoelectric performance of ceramics is explored systematically. Analysis of XRD and Raman spectroscopy confirmed that the orthogonal (O) phase and the tetragonal (T) phase coexisted in each sample at room temperature. By studying the function curve of temperature and dielectric constant er, it is found that the introduction of Li+ in ceramics can have a lower O-T phase transition temperature (TO-T) and a higher Curie temperature (TC), with the TO-T closest to room temperature and the highest coexistence volume proportion of O-T phase in the ceramic when x = 0.03, which had the optimum values for d33 = 252 pC/N and TC = 382 °C. Due to the excellent piezoelectric properties and high TC, it is believed that KNLxN-BNZ piezoceramics can have great application prospects at high temperatures.