Dielectric and piezoelectric properties of non-stoichiometric (K0.5Na0.5)(Nb0.9+xTa0.1)O3 ceramics

In the study, in order to develop the lead-free piezoelectric ceramics for actuator, transformer and other electronic-devices application, (K0.5Na0.5)(Nb0.9+xTa0.1)O3 + 0.5 mol% CuO + 0.2 mol% MnO2 ceramics were prepared by conventional mixed oxide method. The effects of B-site non-stoichiometry in [(K0.5Na0.5)] [(Nb0.9+xTa0.1)O3] ceramics on microstructure and piezoelectric properties were investigated. The density, electromechanical coupling factor (kp), mechanical quality factor (Qm), piezoelectric constant (d33), TC and TO–T of NKNT ceramics with x = 0.0065 showed the optimum values of 4.58 g/cm3, 0.427, 1554, 109 pC/N, 373 °C and 226 °C, respectively, suitable for piezoelectric motor, and transformer applications.

► A study on the several A-site non-stoichiometric composition ceramics have been attempted to improve the piezoelectric properties of ABO3 perovskite structured NKN-based ceramics. However, the research for B-site non-stoichiometric composition ceramics almost never been reported so far.
► In order to develop the lead-free piezoelectric ceramics with high kp and Qm for piezoelectric motor and transformer applications, B-site non-stoichiometric (K0.5Na0.5)(Nb0.9+xTa0.1)O3+ 0.5 mol% CuO + 0.2 mol% MnO2 ceramics were prepared by conventional mixed oxide method.
►  The density, electromechanical coupling factor (kp), mechanical quality factor (Qm), piezoelectric constant (d33), TC and TO-T of NKNT ceramics with x = 0.0065 showed the optimum values of 4.58 g/cm3, 0.427, 1554, 109 pC/N, 373 °C and 226 °C, respectively, suitable for piezoelectric motor and transformer applications.