Microstructure, density, and dielectric properties of lead-free (K _0.44Na_0.52Li_0.04)(Nb_0.96-xTa _xSb_0.04)O₃ piezoelectric ceramics

Lead-free (K0.44Na0.52Li0.04) (Nb0.96-xTaxSb0.04)O3 piezoelectric ceramics were prepared by the conventional solid-state sintering method. The grain growth of the ceramics was inhibited and the relative density was improved with Ta substituting for Nb. Increasing x led to different variations of dielectric properties before and after poling, and prevented the occurrence of orthorhombic-tetragonal phase transition (at To-t). All the ceramics show an intermediate relaxor-like behavior between normal and ideal relaxor ferroelectrics. Significantly enhanced dielectric and piezoelectric properties were obtained in the ceramics with x=0.20. The ceramics are very promising lead-free materials for electromechanical device applications.