Molten salt synthesis of (K_0.47Na_0.47Li_0.06)NbO₃ lead-free piezoelectric ceramics

Abstract

(K_0.47Na_0.47Li_0.06)NbO₃ (KNLN) lead-free ceramics were prepared by molten salt synthesis (MSS) method using k₂CO₃-Na₂CO₃ eutectic mixtures as the flux. The microstructure and piezoelectric properties when sintered at 980–1 030 °C were investigated. The calcined powders were examined by X-ray diffraction. The microstructure of the calcined powders and sintered bodies was observed using a scanning electron microscope (SEM).The piezoelectric constant d ₃₃ was measured using a quasi-static piezoelectric d ₃₃ meter. The planar coupling coefficient K _p was calculated by resonance-antiresonance method. The experimental data for each sample’s performance indicators were the average values of 8 specimens. The relative densities of sintered specimens are above 97%, and the dielectric loss is below 0.03. It was found that (K_0.47Na_0.47Li_0.06)NbO₃ prepared by MSS is compact and lead-free. The piezoelectric constant d ₃₃ is 216 pC·N⁻¹ and the planar electromechanical coupling factor K _p is 0.352.

Keywords

microstructure / piezoelectricity / X-ray diffraction (XRD) / MSS method

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