New Lead-Free (1 - x)(K0.5Na0.5) NbO3-x(Bi0.5Na0.5)ZrO3 Ceramics with High Piezoelectricity

For enhancing the piezoelectric properties of ceramics (Bi0.5Na0.5)ZrO3 (BNZ) was used to partially substitute (K0.5Na0.5)NbO3 (KNN). The addition of BNZ changes the symmetry of KNN ceramics from orthorhombic to tetragonal, and finally to rhombohedral phase. A new phase boundary with both rhombohedral-orthorhombic and orthorhombic-tetragonal phase transitions near room temperature is identified for KNN-0.050BNZ ceramics, where optimum electrical properties were obtained: d(33)=360pC/N, k(p)=32.1%, epsilon(r)=1429, tan=3.5%, and T-C=329 degrees C. The results indicated a new method for designing high-performance lead-free piezoelectric materials.