Effect of orthorhombic-tetragonal phase transition on structure and piezoelectric properties of KNN-based lead-free ceramics

(1 - x)(K0.5Na0.5)(0.95)Li0.05Nb0.93Sb0.07O3-xSrZrO(3) ((1 - x)KNLNS-xSZ) lead free piezoelectric ceramics have been prepared by the conventional solid state reaction method, via adjusting the orthorhombic-tetragonal phase transition temperature to near room temperature with doping SrZrO3, and the effects of SrZrO3 content on polymorphic phase transition have been investigated. These results show that the phase structure of the ceramics was changed from orthorhombic to tetragonal at x >= 0.02 mol, and the orthorhombic-tetragonal phase transition temperature was modified to around room temperature with increasing SrZrO3. Remarkable piezoelectric and ferroelectric properties has been obtained in (1 - x) KNLNS-xSZ system with x = 0.02, which showed a piezoelectric parameter of d(33) = 256 pC N-1, Curie temperature T-c = 270 degrees C, strain levels of 0.16% at 50 kV cm(-1), remnant polarization P-r = 24.9 mu C cm(-2) and coercive field E-c = 10.6 kV cm(-1).