Effects of NaTaO 3 additions on structure and electrical properties of K 0.5Na 0.5NbO 3–Bi 0.5Na 0.5TiO 3–LiSbO 3 piezoelectric ceramics

Abstract

The (1 − x)(0.9405K 0.5Na 0.5NbO 3–0.0095Bi 0.5Na 0.5TiO 3–0.05LiSbO 3)– xNaTaO 3 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 NaTaO 3. The orthorhombic–tetragonal transition temperature ( T O–T) shifted to below room temperature with addition of NaTaO 3. The dielectric and piezoelectric properties of ceramics were enhanced by addition of NaTaO 3. The outstanding electrical properties of piezoelectric coefficient d 33 = 249 pC/N, electromechanical coupling factors, k p = 0.442 and k t = 0.426, relative permittivity, ε 33 T / ε 0 = 1604 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.