Structure and properties of (K 0.5 Na 0.5 ) 0.98 Ag 0.02 Nb 0.96 Ta 0.04 O 3 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, kp = 49%, er = 1382, tan δ = 1.1%, Pr = 24.9 µC/cm2, EC = 1.92 kV/mm, and Tc = 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.