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Aluminum orthovanadate (AlVO4): synthesis and characterization by (27)Al and 51V MAS and MQMAS NMR spectroscopy.

Authors
  • Nielsen, Ulla Gro
  • Boisen, Astrid
  • Brorson, Michael
  • Jacobsen, Claus J H
  • Jakobsen, Hans J
  • Skibsted, Jørgen
Type
Published Article
Journal
Inorganic chemistry
Publication Date
Dec 02, 2002
Volume
41
Issue
24
Pages
6432–6439
Identifiers
PMID: 12444788
Source
Medline
License
Unknown

Abstract

Polycrystalline samples of AlVO(4) have been prepared by two methods of synthesis and characterized by (27)Al and (51)V MAS NMR spectroscopy at 14.1 T. The MAS NMR spectra clearly reveal that essentially pure samples with minor impurities of V(2)O(5) and alumina have been obtained. From these samples, (27)Al quadrupole coupling parameters and isotropic chemical shifts as well as the magnitudes and relative orientations of the (51)V quadrupole coupling and chemical shift tensors have been determined with high precision for AlVO(4). These data have been obtained from a combined analysis of multiple-quantum (MQ) MAS NMR spectra and MAS NMR spectra of the central and satellite transitions. The (27)Al and (51)V NMR data show that the asymmetric unit for AlVO(4) contains three isolated VO(4) tetrahedra, one pentacoordinated Al site, and two AlO(6) octahedra. This is in agreement with the supposition that AlVO(4) is isostructural with FeVO(4) and with a recent structure refinement for AlVO(4) based on powder X-ray diffraction (XRD) data. The favorable agreement between the refined crystal structure from powder XRD and the NMR parameters is apparent from a convincing correlation between experimental (51)V quadrupole tensor elements and calculated (51)V electric field gradient tensor elements obtained by the point-monopole approach. An assignment of the (27)Al NMR data is obtained from similar calculations of the (27)Al electric field gradients and by estimation of the distortion of the AlO(6) octahedra.

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