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RIETVELD REFINEMENT OF POWDER X-RAY DIFFRACTION OF NANOCRYSTALLINE NOBLE METALS – TUNGSTEN TRIOXIDE

Domenii publicaţii > Chimie + Tipuri publicaţii > Articol în revistã ştiinţificã

Autori: Emil Indrea, Ecaterina Bica, Elisabeth-Jeanne Popovici, Ramona-Crina Suciu, Marcela Corina Roşu, Teofil-Dãnuţ Silipaş

Editorial: Revue Roumaine de Chimie, 56(6), p.589 - 593, 2011.

Rezumat:

Tungsten trioxide powders were prepared from peroxo-tungstic acid (PTA) precursor obtained by sol-gel route, in aqueous medium. Two WO 3 samples were doped with noble metals, by „loading” them with silver and metallic palladium. The unit cell parameters of the WO 3 monoclinic phase, the effective crystallite mean size, D eff (nm), and the mean root mean square (rms) of the microstrains , <ε 2 > 1/2 hkl ,were calculated by Rietveld refinement analysis. The distorsion of the WO 3 crystal structure has been used by the ISODISPLACE software tool to transform the P2_1/n structure of WO 3 on to the distortion-mode basis to visualize and quantify the displace modes. The atomic coordinate type has been used to compute three-dimensional structure model as the Radial Distribution Functions g(r) for a 3000-atom model of WO 3 -Ag and WO 3 -Pd systems, which reflects the space correlations between W-O and W-W atoms.

Cuvinte cheie: Tungsten trioxide powders , X-ray diffraction , crystal structure , unit cell parameters