Solution combustion synthesis and characterization of lead-free piezoelectric sodium niobate (NaNbO3) powders

Nano-crystalline sodium niobate (NaNbO3) powder was synthesized by the solution combustion synthesis of sodium nitrate (NaNO3) and Nb2O5 using glycine as the fuel. The chemical reaction, nucleation mechanisms and influence of the fuel-to-oxidizer ratio to phase formation were studied. The precursor and product powders were characterized, using thermo gravimetric analysis (TGA), differential thermal analysis (DTA), the X-ray diffraction technique (XRD), scanning electron microscope (SEM) and Fourier transform infrared (FTIR) spectroscopy. As-prepared powder possesses an orthorhombic crystal structure with an X-ray diffraction pattern that could be matched with the perovskite, NaNbO3 JCPDS no. 82-0606. Perovskite NaNbO3 phase, with a mean crystalline size (calculated by X-ray line broadening) ranging from 44.51 ± 11.99 nm (ratio of 0.7) to 26.11 ± 13.69 nm (ratio of 2.0) was obtained. The SEM image shows polyhedral-shaped powder with a mean particle size of 137 ± 52 nm and 226 ± 46 nm for as-prepared and calcined powder, respectively. © 2010 Elsevier B.V. All rights reserved.