New Lead‐Free (1 − x )(K 0.5 Na 0.5 )NbO 3 – x (Bi 0.5 Na 0.5 )ZrO 3 Ceramics with High Piezoelectricity

For enhancing the piezoelectric properties of ceramics ( Bi 0.5 Na 0.5 ) ZrO 3 ( BNZ ) was used to partially substitute ( K 0.5 Na 0.5 ) NbO 3 ( 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 –0.050 BNZ ceramics, where optimum electrical properties were obtained: d 33 = 360 pC/N, k p = 32.1%, ε r = 1429, tanδ = 3.5%, and T C = 329°C. The results indicated a new method for designing high‐performance lead‐free piezoelectric materials.