Search results for "Nanocrystalline WO3 and HxWO3 powders"

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Raman study of the phase transitions sequence in pure WO3 at high temperature and in HxWO3 with variable hydrogen content

1999

Abstract An extensive investigation of the temperature dependence of Raman spectra has been carried out on WO 3 powders from room temperature to 800°C. In particular the orthorhombic-to-tetragonal phase transition occurring at about 740°C has been studied for the first time. The Raman active mode at 710 cm −1 of the orthorhombic phase disappears from the spectrum at temperature below the phase transition point and the Raman activity in the tetragonal phase results very low. A comparative study of hydrogenated tungsten bronzes H x WO 3 ( x ≤0.23), where the same transition sequence is driven by an increase of the proton concentration from x =0 to 0.23, reveals similar behaviour of the high f…

Nanocrystalline WO3 and HxWO3 powdersPhase transitionNanocrystalline WO3 and HxWO3 powders phase transitions Raman spectroscopy.ChemistryAnharmonicityAnalytical chemistrychemistry.chemical_elementMineralogyGeneral ChemistryTungstenCondensed Matter Physicsphase transitionsTetragonal crystal systemsymbols.namesakeMolecular vibrationPhase (matter)symbolsRaman spectroscopy.General Materials ScienceOrthorhombic crystal systemRaman spectroscopy
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