Effect of LiF and HfO2 on the LKNNT lead-free piezoelectric ceramics

In this work, the HfO₂ and LiF have been used to improve the piezoelectric behavior of Li_0.058(K_0.480Na_0.535)_0.966(Nb_0.9Ta_0.1)O₃(LKNNT) lead-free ceramics prepared by the conventional solid-state method. The addition of little amount HfO₂/LiF co-doped will not change the phase structure of LKNNT ceramics. In this study, due to the co-doping of HfO₂/LiF. The relative density of LKNNT can up to 98.73%, piezoelectric constant d₃₃ is 347 pC/N, electric-mechanical coupling coefficient k_p is 48%, and relative dielectric constant ε_r is 2701, and tanδ = 1.3%. Therefore, it is an effective way to improve the piezoelectric properties of KNN-based ceramics by the addition of HfO₂ and LiF.