Études des spectres infrarouges de polymolybdates et polywolframates alcalins anhydres entre 4000 et 200 cm−1
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Cited by (38)
A temperature-dependent Raman scattering and X-ray diffraction study of K<inf>2</inf>Mo<inf>2</inf>O<inf>7</inf>·H<inf>2</inf>O and ab initio calculations of K<inf>2</inf>Mo<inf>2</inf>O<inf>7</inf>
2021, Spectrochimica Acta - Part A: Molecular and Biomolecular SpectroscopyPhysical, Optical, Structural and Thermal Studies of xWO<inf>3</inf> + (30 − x)As<inf>2</inf>O<inf>3</inf> + 70TeO<inf>2</inf> (where x = 10, 20, 30 mol%) glasses by UV–vis, Raman, IR and DSC Studies
2020, OptikCitation Excerpt :In the present glass system, peak A is assigned to stretching vibrations of W–O–W bonds of WO6 units [83]. The peak B is attributed to bending vibrations of As–O–W linkages and Te–O–W linkages because of comparable vibrational frequency (ν4) of WO3 and As2O3 units in the glass system under study [84]. Most of the authors reported in the literature, this peak due to the bending vibrations of Te–O–Te linkages of TeO4 tbp units in tellurite glasses [85–87].
Polyethylene glycol assisted one-pot hydrothermal synthesis of NiWO<inf>4</inf>/WO<inf>3</inf> heterojunction for direct Methanol fuel cells
2018, Electrochimica ActaCitation Excerpt :Since XRD results of the sample indicated the absence of any crystalline WO3 hence this band is likely due to the presence of the amorphous WO3 species; in agreement with the UV–Vis results. The absence of the bands at 805 cm−1 and 750 cm−1 due to the stretching vibrations of the bridging WOW bonds [44] confirms the assignment concerning the NiWO4 formation. Additionally, the broadness of the 450 cm−1 band confirms that it can belong to either vibrations of NiO6 polyhedra (413 cm−1) and WO3 (449 cm−1) [45,46] or indeed verify the formation of the NiWO4.
Pressure dependent Raman studies in the K<inf>2</inf>Mo<inf>2</inf>O<inf>7</inf>·H<inf>2</inf>O crystal
2018, Vibrational SpectroscopyCitation Excerpt :Additionally, the coordinates of the bonds in the octahedral and pyramidal groupings make predominant contributions to the vibrations in the spectral region leading to a decrease in the gap (130 cm−1) for the K2Mo2O7·H2O (see Fig. 3), as the Raman spectra are affected by the bridging bonds in the crystal lattice. As previously reported, the coordinates of the bonds in the octahedral grouping deliver the predominant contribution to the vibrations in the 940–460 cm−1 region, which is considerably broader than the wavenumber range for the stretching vibrations of the isolated MoO4 octahedron [29,30]. The motions of the oxygen atoms, which connect two MoO6 octahedrons, are related with the stretching modes at 940–740 cm−1and bending (deformation) modes in the range of 600–190 cm−1.
Temperature induced phase transformations on the Li<inf>2</inf>MoO<inf>4</inf> system studied by Raman spectroscopy
2017, Journal of Molecular StructureCitation Excerpt :Single molybdates and tungstates with the general composition of the A2MO4 (A = Li, Na, K, Rb, Cs; M = Mo, W), has attracted a considerable attention in recent years due to the formation of a large number in different structures with different physical properties of greater interest [1–6]. The A2MO4 family of molybdates has also been a subject of many studies, including structural transformations duly investigated by differential thermal analysis (DTA), high-temperature X-ray diffraction (XRD) [4–7] and high-temperature Raman spectroscopy [3]. Therefore, the present study reports the temperature-dependent Raman studies of the Li2MoO4 in order to obtain information on the structural changes that occur in this said material, as the result of a high-temperature phase transformation.
Unprecedented high photocatalytic activity of nanocrystalline WO<inf>3</inf>/NiWO<inf>4</inf> hetero-junction towards dye degradation: Effect of template and synthesis conditions
2014, Applied Catalysis B: EnvironmentalCitation Excerpt :The IR spectra of calcined samples are shown in Fig. 6. In the IR spectrum of the NiW1SS sample, broad bands at 950, 850, 666 and 450 cm−1 are depicted to confirm the NiWO4 formation where the band at 950 cm−1 is ascribed to the stretching modes of the WO terminal bond present in each octahedron of WO3 [39]. Since XRD results of the sample indicated the presence of negligible amounts of low crystalline WO3 hence this band is likely due to the highly dispersed WO3 species.