Synthesis of Lead-Free (K, Na)(Nb, Ta)O₃ Nanopowders Using a Sol–Gel Process

Lead-free (K_0.5Na_0.5)(Nb_0.7Ta_0.3)O₃ piezoelectric material was successfully synthesized via a sol–gel process. Crystalline (K_0.5Na_0.5)(Nb_0.7Ta_0.3)O₃ nanopowders were obtained after heat treatment at 700 °C. The particle size was estimated to be 87nm±23 nm. The transmission electron microscopy images showed that individual nanoparticles were single crystalline and had a pseudo-cubic structure with a lattice parameter of μ3.96 A. Both X-ray diffraction and scanning electron microscopy studies consistently showed that the crystallization of the (K_0.5Na_0.5)(Nb_0.7Ta_0.3)O₃ occurred slightly above 500 °C. The samples have an appropriate stoichiometry as found via energy dispersive X-ray spectroscopy. The demonstration of the synthesis of (K_0.5Na_0.5)(Nb_0.7Ta_0.3)O₃ via a sol–gel process as presented in this paper can provide an important foundation for the development of a synthetic route towards (K_0.5Na_0.5)(Nb_0.7Ta_0.3)O₃ doped with various other elements for high performance piezoelectric devices.