BiFeO3-doped (Na0.5K0.5)NbO3 lead-free piezoelectric ceramics.

Lead-free piezoelectric ceramics (1-x)(Na0.5K0.5)NbO3-xBiFeO3 (x=0∼0.07) were synthesized by the solid-state reaction. Differential scanning calorimetry (DSC) measurements revealed that an increase in the amount of BiFeO3 dopant resulted in a decrease in the orthorhombic-tetragonal and tetragonal-cubic phase transition temperature of the material. One percent BiFeO3 additive suppressed grain growth, which not only benefits the sintering of ceramics but also enhances the piezoelectric and ferroelectric properties, where d33=145pC/N, kp=0.31, Qm=80, Pr=11.3 μC cm-2 and Ec=16.5 kV cm-1. As xBF>0.01, both piezoelectric and ferroelectric properties decreased rapidly with an increasing amount of dopant.