Structure and piezoelectric properties of new ternary K0.5Na0.5NbO3–LiSbO3–CaTiO3 lead-free piezoceramics

Abstract

New ternary (1−x)K0.5Na0.5NbO3–x(0.80LiSbO3–0.20CaTiO3) lead-free ceramics were fabricated by a conventional ceramic technique and their structure and piezoelectric properties were studied. The results of X-ray diffraction reveal that LiSbO3 and CaTiO3 diffuse into the K0.5Na0.5NbO3 lattices to form a new solid solution with a perovskite structure. After the addition of LiSbO3 and CaTiO3, the cubic-tetragonal and tetragonal-orthorhombic phase transitions shift to lower temperatures. Coexistence of the orthorhombic and tetragonal phases is hence formed in the ceramics with 0.03 < x < 0.07 at room temperature, leading to a significant enhancement of the piezoelectric properties. For the ceramics with x = 0.04–0.06, the piezoelectric properties become optimum: d33 = 172–253 pC/N, kP = 49.9–55.5%, kt = 49.2–52.1% and TC = 348–373 °C. The ceramic with x = 0.04 also exhibits a good thermal stability of piezoelectric properties.