Phase Transition and High Piezoactivity of Sb Doped (Na_0.53K_0.435Li_0.035)Nb_0.94Ta_0.06O₃ Lead-Free Ceramics

Lead-free piezoelectric ceramics with the composition of (Na_0.53K_0.435Li_0.035)Nb_0.94-xSb_xTa_0.06O₃ (NKLNST) are synthesized by a conventional solid-state sintering process. An MPB-like region between orthorhombic and pseudocubic phases is found in this system. The density, piezoelectric and dielectric properties are enhanced greatly in this region. A composition (Na_0.53K_0.435Li_0.035) (Nb_0.86Sb_0.08Ta_0.06)O₃ is found to have excellent
electrical properties: d₃₃=320pC/N, k_p=49% and kt=43%, as well as relatively low loss, tan δ=4.2%, and high relative density higher than 96%, which indicate that this ceramics is a promising lead-free piezoceramics replacing for lead zirconate titanate.