Structure and electrical properties of [(K0.49Na0.51)1-xLix](Nb0.90Ta0.04Sb0.06)O3 lead-free piezoceramics

Lead-free [(K0.49Na0.51)(1-x)Li-x](Nb0.90Ta0.04Sb0.06)O-3 (KNLNTS) ceramics were prepared by a conventional ceramic processing method, and the effects of Li content on the crystal phases and electrical properties of the ceramics were investigated. A secondary phase was identified by XRD analysis when x=0.08, indicating that the maximum solid solubility of lithium in KNLNTS solid solutions is lower than 8 mol%. The Curie temperature T-C increased while the polymorphic phase transition (PPT) temperature TO-T. decreased with the increasing Li content. The coexistence of orthorhombic and tetragonal phases was observed near room temperature when x=0.04. The optimum electrical performance, i.e. piezoelectric coefficient d(33)=215 pC/N, electromechanical coupling coefficient k(p)=0.313, k(t)=0.306, relative permittivity epsilon(T)(33)/epsilon(0)=805 and loss tangent tan delta=0.045, was obtained for x=0.04. (C) 2012 Elsevier Ltd and Techna Group S.r.l. All rights reserved.