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

Abstract

The K _xNa_(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 K _xNa_(1-x)NbO₃ such as piezoelectric constant d ₃₃ = 115 pC/N, mechanical quality factor Q _m = 20, Curie temperature T _c = 365 °C, ε ^T ₃₃/ε₀= 588.1, dielectric loss tan δ = 0.024, bulk density (ρ) = 3.08 g/cm³, remnant polarization (P _r) = 8.87 μC/cm² and coercive field (E _c) = 13.79 kV/cm were obtained at x = 0.46.

Keywords

lead-free piezoelectric ceramics / solid-state sintering / K/Na ratio / electrical properties