Na0.5K0.5NbO3 and 0.9Na0.5K0.5NbO3–0.1Bi0.5Na0.5TiO3 nanocrystalline powders synthesized by low-temperature solid-state reaction

Nanocrystalline powders of K0.5Na0.5NbO3 (KNN) and 0.9Na0.5K0.5NbO3–0.1Bi0.5Na0.5TiO3 (KNN–BNT) have been prepared using a low-temperature solid-state reaction. Phase development of the powders incurred during various calcination temperatures was examined by X-ray diffraction (XRD). Crystallite size and particle morphology of KNN powders were examined by XRD and transmission electron microscopy, respectively. Perovskite phase was formed at the temperature as low as 500 °C, and the average crystallite size of KNN powders depended on calcination temperature. In addition, the crystalline structure of KNN powders tended to change from tetragonal symmetry to orthorhombic symmetry with increase in crystallite size. Similar results were obtained in KNN–BNT system. The developed method is well suited for the mass production of niobate nanocrystalline powders due to its simplicity and low cost.

(b1) Magnified Raman spectra of KNN calcined from 500 °C to 1000 °C in the wavenumber range from 420 and 740 cm−1 as a function of the composition and Lorentzian fits of the individual peaks of the Eg (ν2) and A1g (ν1) Raman modes. Evolution of Raman shift (b2) and FWHM (b3) of A1g mode in function of calcination temperature are also shown.Figure optionsDownload as PowerPoint slideHighlights
► K0.5Na0.5NbO3 nanopowder has been synthesized at low temperature.
► The crystalline structure of the powder depends on the grain size.
► The method is well suited to the mass production of niobate nanopowders.
► The route is available for preparing niobate-titanate solid solution nanopowders.