Effect of mechanical activation on the structure and ferroelectric property of Na0.5K0.5NbO3

Mechanical activation synthesis of Na0.5K0.5NbO3 (NKN) was studied in order to explore the effect of mechanochemical interaction on the crystal structure and microstructure of NKN powder and ceramic. A single phase, nanocrystalline perovskite NKN powder has been derived from a mixture of oxide/carbonates via a mechanical activation route with heating at an elevated temperature. With the increase in milling time, the distortion of orthorhombic structure for NKN was weakened and the cell volume of NKN powder slightly decreased. The relative density and remnant polarization of NKN ceramics were improved, and the grain became uniform and smaller for prolonged milling NKN. The developed method is well suited for the production of NKN nanocrystallite powders and refined grain NKN ceramics.

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► Nanocrystallite NKN powder was fabricated by mechanical alloying method.
► Impurities were introduced into the NKN lattice during the mechanical activation.
► The orthorhombic distortion of NKN was weakened for a prolonged milling.
► The impurities from milling tools resulted in a fine-grained ceramic.
► The ferroelectric properties would worsen for the prolonged milling NKN.