Synthesis and characterization of lead-free sodium niobate powder

Sodium niobate (NaNb[O.sub.3]) fine powders were synthesized by hydrothermal method using ammonium niobate (V) oxalate hydrate ([C.sub.4][H.sub.4]NNb[O.sub.9] x [H.sub.2]O), sodium hydroxide (NaOH) and sodium citrate hydrate ([C.sub.6][H.sub.9][Na.sub.3][O.sub.9]) as precursors. The samples were characterized by X-Ray diffraction (XRD), scanning electron microscopy (SEM), AFM (Atomic Force Microscopy), UV-VIS spectroscopy and Fourier Transform Infrared Spectroscopy (FTIR). X-ray diffraction for powder obtained by hydrothermal method revealed three phases mixture (NaNb[O.sub.3], [Nb.sub.2]O5, [Na.sub.2][C.sub.2][O.sub.4]). In order to obtain a material with perovskite structure, the powder was treated for 6 h at 600°C. After calcination, the X-ray powder diffraction (XRD) patterns shown reflections of a pure cubic structure (space group Pm-3m) with lattice parameters (a=b=c=3.909Å) comparable to those reported in the literature. The average particle sizes estimated by SEM image were 2-3 micrometers. Keywords: sodium niobate, hydrothermal method, X-ray diffraction, scanning electron microscopy