Effect of Sintering Temperature on Electrical Properties of Na0.5K0.5NbO3Lead-Free Piezoelectric Ceramics Prepared by Normal Sintering

The effects of sintering temperature on microstructure, density and electrical properties of Na0.5K0.5NbO3 prepared by normal sintering at 1020–1100°C were investigated. All the Na0.5K0.5NbO3 ceramics showed an orthorhombic structure similar to that of KNbO3 ceramics, while raising sintering temperature resulted in the shifting of diffraction peaks to a lower value and the formation of a second phase due to the excess volatilization of Na. Both density and d33 of the sintered samples increase with increasing sintering temperature. The density of the sample sintered at 1080°C reaches a maximum value (4.22 g/cm3, 92% of the theoretical density). The sample sintered at 1060°C showed a maximum d33 value of about 122 pC/N and the highest T c of about 409°C, and the corresponding E c and P r were about 13 kV/cm and 15 μ C/cm2, respectively.