Effects of NaTaO3 additions on structure and electrical properties of K0.5Na0.5NbO3–Bi0.5Na0.5TiO3–LiSbO3 piezoelectric ceramics

The (1 − x)(0.9405K0.5Na0.5NbO3–0.0095Bi0.5Na0.5TiO3–0.05LiSbO3)–xNaTaO3 lead-free piezoelectric ceramics were fabricated by conventional ceramic technique. The structure, dielectric, ferroelectric and piezoelectric properties of the ceramics were investigated. The X-ray diffraction (XRD) analysis revealed that the ceramics sintered in air at 1060–1140 °C for 3–4 h formed single phase pervoskite solid solutions with the tetragonal symmetry at room temperature. The microstructure of the ceramics became homogeneous with addition of NaTaO3. The orthorhombic–tetragonal transition temperature (TO–T) shifted to below room temperature with addition of NaTaO3. The dielectric and piezoelectric properties of ceramics were enhanced by addition of NaTaO3. The outstanding electrical properties of piezoelectric coefficient d33 = 249 pC/N, electromechanical coupling factors, kp = 0.442 and kt = 0.426, relative permittivity, image and loss tangent, tan δ = 0.023 were obtained at x = 0.06. The related physical mechanisms for the enhancement of dielectric and piezoelectric properties were discussed.