Synthesis and electrical, optical and phonon properties of nanosized Aurivillius phase Bi2WO6

Nanoparticles of bismuth-layered ferroelectric and photocatalytic material, Bi2WO6, have been prepared by mechanochemical synthesis and firing of amorphous precursor prepared in metathesis reaction. The effect of different synthesis methods and crystallite size on the structure and properties of Bi2WO6 nanoparticles have been investigated using the XRD, TEM, DTA, DTG, diffuse reflectivity, conductivity measurements, Raman and infrared spectroscopy. The results show that the smallest particles could be obtained by mechanochemical synthesis. However, this method introduced large number of crystal defects. The conductivity of this sample is higher by half an order of magnitude, in comparison with conductivities measured for the other samples studied in this paper or previously reported in the literature for Bi2WO6. Our results also show that firing the amorphous precursor with NaNO3 by-product yields material composed of small, well-crystallized particles containing small number of crystal defects. This result shows that this synthesis method is the best route to enhance photocatalytic activity of Bi2WO6. Raman and IR studies also suggest that the orthorhombic distortion diminishes with decreasing particle size.