Structure and properties of (K_0.5Na_0.5)_0.98Ag_0.02Nb_0.96Ta_0.04O₃ piezoelectric ceramics doped by CuO

Low-temperature sintering technology can control the volatilization of sodium and potassium ions during high-temperature preparation to obtain excellent physical properties of ceramics. In this research, we used the traditional ceramic preparation technology. KNN-based lead-free piezoelectric ceramics were prepared for the first time at home and abroad by using CuO and Na₂O as collective additives under low sintering temperature (1020 °C) conditions. X-ray diffraction, scanning electron microscopy, and other modern test analyses show that KNANTC ceramics can form a pure perovskite structure of tetragonal phase in the total research range when 0.01 mol Na₂O is used as a supplement to the A position of KNN piezoelectric ceramics. A moderate amount of CuO doping can simultaneously enhance liquid-phase sintering, promote grain growth, improve the density of ceramics, and achieve excellent electrical properties. The test results of KNANTC piezoelectric ceramics show good electrical properties when x = 0.035, that is, d₃₃ = 343 pC/N, k_p = 49%, ε_r = 1382, tan δ = 1.1%, P_r = 24.9 µC/cm², E_C = 1.92 kV/mm, and T_c = 306 °C. These results indicate that KNANTC-x is a promising lead-free piezoelectric ceramic material that can gradually replace the traditional PZT-based piezoelectric ceramics in the future.