Phase Structure, Microstructure and Electrical Properties of KxNa(1-x)NbO3 Piezoelectric Ceramics with Different K/Na Ratio

The KxNa(1-x)NbO3 (x = 0.45, 0.46, 0.47, 0.48, 0.49, 0.50) lead-free piezoelectric ceramics was fabricated by conventional solid-state sintering method. It was found that the ratio of alkaline metal would affect the microstructure, bulk density, and optimum sintering temperatures of ceramics. Meanwhile, the electrical properties were also influenced by modulating the K/Na ratio, exhibiting corresponding composition-dependent properties. The optimum electrical properties of KxNa(1-x)NbO3 such as piezoelectric constant d33 = 115 pC/N, mechanical quality factor Qm = 20, Curie temperature Tc = 365 °C, eT33/e0= 588.1, dielectric loss tan δ = 0.024, bulk density (ρ) = 3.08 g/cm3, remnant polarization (Pr) = 8.87 μC/cm2 and coercive field (Ec) = 13.79 kV/cm were obtained at x = 0.46.