Effect of Mn Doping Amount on Properties of 0.96K_0.5Na_0.5NbO₃-0.04Bi_0.5Na_0.5ZrO₃ Lead-Free Piezoelectric Ceramics

The 0.96K_0.5Na_0.5NbO₃-0.04Bi_0.5Na_0.5 ZrO₃+xMnCO₃ (0.96KNN-0.04BNZ+xMn, x=0, 0.1%, 0.3%, 0.5%, 0.7%, mass fraction) lead-free piezoelectric ceramics were prepared by conventional solid state reaction method. The effects of Mn doping amount on the crystal structure, microstructure, piezoelectric and dielectric properties of the lead-free piezoelectric ceramics were investigated. The results show that the 0.96KNN-0.04BNZ+xMn ceramics had a pure perovskite structure. With increasing x, the phase of the ceramics changed from the coexistence of orthorhombic and tetragonal phases to orthorhombic phase; the bulk density, piezoelectric constant, planar electromechanical coupling factor and dielectric constant first increased and then decreased; the mechanical quality factor increased; the dielectric loss angle tangent, remanent polarization, coercive field and Curie temperature decreased. The comprehensive performance of the ceramics was the best when x was equal to 0.3wt%.