Effects of Li content on the phase structure and electrical properties of lead-free (K0.46-x/2Na0.54-x/2Lix)(Nb0.76Ta0.20Sb0.04)O3 ceramics

Lead-free (K0.46-x/2Na0.54-x/2Lix)(Nb0.76Ta0.20Sb0.04)O-3 piezoelectric ceramics were prepared by the conventional solid state sintering method without cold-isostatic pressing process. The x-ray diffraction and Raman scattering results show that the phase structure of the ceramics undergoes a transition from pseudocubic to tetragonal phase with increasing x from 0 to 0.10. Significantly enhanced electrical properties (d(33)=259 pC/N, k(p)=0.42, epsilon(r)=1653, and tan delta=0.027) were obtained in the ceramics with x=0.04 near the morphotropic phase boundary, and only the tetragonal-cubic phase transition was observed above the room temperature in the epsilon(r)-T curve. The temperature stability of the ceramics with x=0.04 was also investigated. (c) 2007 American Institute of Physics.