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

Nanocrystalline powders of K_0.5Na_0.5NbO₃ (KNN) and 0.9Na_0.5K_0.5NbO₃–0.1Bi_0.5Na_0.5TiO₃ (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.