Raman spectra of some M^IIV₂O₆ brannerite‐type metavanadates

Abstract

The Raman spectra of polycrystalline samples of the metavanadates M"V,O,, (with M = Ca, Cd, Cu and Mg), belonging to the brannerite structural type, have been recorded. A general assignment, supported by comparisons with known vibrational properties of other oxovanadium species, is proposed. The compounds only give poorly defined IR spectra, which are not useful for the analysis of the vibrational behaviour.

Exploring the coordination change of vanadium and structure transformation of metavanadate MgV2O6 under high pressure

“…Factor group analysis gives the following irreducible representation of the optic modes Г opt  = 8A g (R) + 4B g (R) + 4A u (IR) + 8B u (IR) and the acoustic modes (A u  + 2B u ) of MgV 2 O 6 35. Twelve phonon modes in total were discernible in the Raman spectrum at the ambient condition and the assignments of Raman bands, which are in good agreement with previous works354041424344, are listed in Supplementary Table S1. In addition, the frequencies, pressure coefficients, and Grüneissen parameters of the different modes are summarized in Supplementary Table S2.…”

A 1D Honeycomb‐Like Amorphous Zincic Vanadate for Stable and Fast Sodium‐Ion Storage

“…The resemblance of transform infrared spectroscopy (FTIR) and Raman spectra further indicates the amorphous ZVO‐AH is zincic vanadate material instead of a mixture of ZnO and VO x (Figure S15, Supporting Information). The characteristic Raman perks arise at 862 and 910 cm −1 , corresponding to antisymmetric stretching vibration and stretching vibration modes of VOV and VO, respectively (Figure b) . Obviously, the Raman bands of ZVO‐AH shift to lower wavenumbers and become broader and weaker, which indicates the distorted lattices with variations in bonding length and angle, and the short‐range order arise together in ZVO‐AH sample …”

Redetermination of metarossite, CaV5+ 2O6·2H2O

“…In particular, all bands originating from O-H stretching vibrations disappeared, suggesting a complete dehydration of the sample. Moreover, the spectrum below 1200 cm À1 was found to match that of synthetic CaV 2 O 6 ( Baran et al, 1987). In addition, we observed similar Raman spectra collected from a metarossite fragment that was heated in air in an oven at 373 K for 12 h. Single crystal X-ray diffraction analysis on the heated crystal revealed monoclinic symmetry with unit cell parameters a = 10.0 (1), b = 3.6 (2), c = 6.9 (6) Å , = 105 (6) , which match those reported for brannerite (Szymanski & Scott, 1982).…”

“…However, we were unable to obtain more detailed structure information for the heated sample due to its poor crystallinity (caused probably by dehydration). A number of synthetic metavanadates, such as those with formula M 2+ V 2 O 6 where M = Cu, Cd, Mg or Mn, are found to be isostructural with brannerite (Baran et al, 1987;Mü ller-Buschbaum & Kobel, 1991). There are also many hydrated forms of these compounds, including synthetic CuV 2 O 6 Á2H 2 O (Leblanc & Ferey, 1990), and CdV 2 O 6 Á2H 2 O (Ulická , 1988), as well as natural dickthomssenite MgV 2 O 6 Á7H 2 O (Hughes et al, 2001) or ansermetite MnV 2 O 6 Á4H 2 O (Brugger et al, 2003).…”