Sol-gel synthesis and XPS characterization of sodium-vanadium oxide bronze thin films

A sodium-vanadium oxide bronze has been synthesized from V2O5 and Na2SO4 by using a sol-gel technology . The powders were dissolved in a solution of hydrogen peroxide and heated up to 350 K for the dissociation of the peroxide complexes. The obtained gel was deposited on the metallic substrate and dried in air at room temperature. The produced xerogel was heated up to 580 K in pure oxygen atmosphere for the removal of water from the xerogel. Starting materials, xerogel, as well as a final product were investigated by means of XPS technique. The binding energies of the V 2p peaks were shifted by 0.4 eV to the smaller BE values in comparison with pure vanadium pentoxide powder and xerogel. BE of Na1s in the bronze is higher for 0.7 eV and 0.8 eV than in the Na2SO4 powder and xerogel, respectively. XPS spectra testify that the chemical bonds of vanadium, oxygen and sodium in the bronze differ from similar bonds in the starting materials. The sulphur presence was detected only in the xerogel but not in the final bronze composition.