Effects of NaSbO3 on phase structure and electrical properties of K0.5Na0.5NbO3–LiTaO3–NaSbO3 piezoelectric ceramics

Abstract

The (0.96–x)K0.5Na0.5NbO3–0.04LiTaO3–xNaSbO3 (abbreviated as KNN–LT–xNS, x = 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08) lead-free piezoelectric ceramics were fabricated by conventional ceramic technique. The crystal structure, dielectric, ferroelectric and piezoelectric properties of the ceramics were investigated. The Curie temperature (TC) and the polymorphic phase transition temperature (TO−T) of the ceramics decreased gradually with the increase of NaSbO3. In addition, a coexistence of orthorhombic and tetragonal phases in the ceramics was identified in the composition range of 0.05 ≤ x ≤ 0.08. The ceramic with a composition of x = 0.06, which was close to the orthorhombic side of the polymorphic phase transition (PPT) region, exhibited excellent electrical properties with piezoelectric coefficient d33 = 233 pC/N, planar electromechanical coupling coefficient kp = 0.328, remnant polarization Pr = 14.7 μC/cm2, coercive field Ec = 11.7 kV/cm, relative permittivity \( \varepsilon_{33}^{\text{T}} /\varepsilon_{0} \) = 1,033, and loss tangent tan δ = 0.063. The ceramics had relatively low Qm value in the range of 10–37.