Piezoelectric and Dielectric Properties of [(NaxK(1-x))0.985Bi0.015](Nb0.97Ti0.03)O3 Ceramics

[(NaxK(1-x))(0.985)Bi-0.015](Nb0.97Ti0.03)O-3 (x=0.40-0.65) lead-free piezoelectric ceramics were synthesized by solid-state reaction method. The influences of different x value on the phase structure, microstructure, piezoelectric and dielectric properties of samples were studied in detail. The results indicate that all samples possess pure perovskite structure and the Curie temperature of all samples are in the temperature range of 340-365 degrees C. The ceramic sample with x=0.40 is in the tetragonal symmetry at room temperature and with the increase of x content, the phase structure of samples change gradually from pure tetragonal phase to coexistence of tetragonal and ortho-rhombic phase, while the ceramic sample with x=0.65 has tetragonal phase. The polymorphic phase transition (PPT) from orthorhombic to tetragonal symmetry near room temperature locates in the composition of 0.45 <= x <= 0.63 in which the ceramic samples possess relatively high piezoelectric activity. The ceramic sample (x=0.60) with optimum piezoelectric properties (d(33)=253 pC/N, k(p)=0.43, T-C=359 degrees C) is a promising lead-free piezoelectric material.