Fabrication of Lead-Free Piezoelectric (Na_0.5K_0.5)NbO₃ Ceramics by a Modified Solid-State Reaction Method

ABSTRACT Sodium potassium niobate, (Na_0.5K_0.5)NbO₃, fine powder has been successfully synthesized at the low temperature of 550°C through a modified solid-state reaction method, in which urea [CO(NH₂)₂] plays an important role. High-density (Na_0.5K_0.5)NbO₃ ceramics could be obtained by conventional sintering of the synthesized (Na_0.5K_0.5)NbO₃ fine powder with the addition of 0.03 mol% Co₃O₄ as a sintering additive. The crystal structure, microstructure, and dielectric and piezoelectric properties were characterized. The (Na_0.5K_0.5)NbO₃ ceramic showed a comparatively saturated P-E hysteresis loop. The (Na_0.5K_0.5)NbO₃ ceramic also displayed piezoelectricity with a piezoelectric constant d₃₃ of 126 pC/N and a planar electromechanical coupling factor k_p of 33%.

Digital Object Identifier 10.1109/TUFFC.2008.744

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