Fabrication of dense (K,Na)NbO3 ceramics by modified two-step sintering

Abstract Achieving a high relativity density value in the (K,Na)NbO3 based ceramics is usually quite difficult due to the volatility of alkali elements. A modified two-step sintering technique has been attempted to conveniently fabricate the dense (K,Na)NbO3 based ceramics through the solid state reaction route in this work. The chemical composition (K0·50Na0·50)NbO3 was chosen as the test example. As the result, the obtained ceramic shows the much improved microstructure with a relative density value of 97·1% and comparatively uniform grain size distribution, thus differs largely from the corresponding one densified by conventional sintering. Meanwhile, a considerable increase in the piezoelectric constant d33 (from 125 to 143 pC N–1) is also observed. Therefore, modified two-step sintering is considered as an effective means for fabricating the dense KNN based lead-free piezoelectric ceramics.

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