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

Lead-free [(K0.49Na0.51)1−xLix](Nb0.90Ta0.04Sb0.06)O3 (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 T O–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 View the MathML sourceε33T/ε0=805 and loss tangent tan δ=0.045, was obtained for x=0.04