Influence of bismuth doping on structure and properties of potassium sodium niobate lead-free ceramics

Lead-free piezoceramics bismuth doping potassium sodium niobate ((K0.5Na0.5) 1-3x BixNbO3) (KNBN) was prepared by a conventional ceramic processing. The effect of bismuth on the density and electrical properties of potassium sodium niobate (KNN) ceramics was investigated. The results show that the ceramic with x of 1% has the superior electrical properties, i.e., the maximum piezoelectric coefficient of 121 pC/N, the moderate relative dielectric constant of 575 and the moderate dielectric loss of 5.82%, respectively. The saturated hysteresis loops of the sample are obtained, and the remanent polarization is 12.67 μC/cm2 and the coercive electric field is 13.58 kV/cm. The phase translation temperature from orthorhombic to tetragonal is 131°C, and the Curie temperature is 400°C.