Chemical, structural, and morphological characterization of tungsten nanoparticles synthesized by a facile chemical route

Tungsten nanoparticles (W-NPs) with average sizes ranging between 30 and 80 nm were prepared by thermolytic decomposition of tungsten hexacarbonyl in presence of a mixture of surfactants, oleic acid and oleyl amine. Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy (XPS) results reveal that the surfactants oleic acid and oleyl amine bonded to the surface of W-NP through their functional groups, which in turn render stability to the nanopowders with respect to coarsening or aggregation. XPS results also confirm that carbon is present only at the surface of the W-NPs. The as-synthesized W-NPs were amorphous, and on heat treatment at 600 degrees C for 1 h, the amorphous powders transform into a body-centered cubic crystalline form (alpha-W).