Accession Number : ADA315145

Title :   X-Ray Absorption and Magnetic Resonance Spectroscopic Studies of LixV6Ol3.

Descriptive Note : Technical rept.,

Corporate Author : NAVAL ACADEMY ANNAPOLIS MD

Personal Author(s) : Stallworth, P. E. ; Kostov, S. ; Den Boer, M. L. ; Greenbaum, S. G. ; Lampe-Onnerud, C.

PDF Url : ADA315145

Report Date : 27 JUN 1996

Pagination or Media Count : 31

Abstract : Polycrystalline Li(x)V6O13 samples, 0.5< or = x< or = 6, were prepared by chemical intercalation in n-butyl lithium and investigated by various spectroscopic techniques, including x-ray absorption, electron paramagnetic resonance (EPR), and (7)Li solid state nuclear magnetic resonance (NMR). The EPR results, which are sensitive to the total V(+4) concentration, are consistent with the expectation that the formal oxidation state of vanadium decreases monotonically with the addition of Li. This is confirmed by near-edge x-ray absorption fine structure spectra at the vanadium K-edge. The extended x-ray absorption fine structure shows that the local symmetry of the vanadium sites, as determined by the intensity of the first V-O peak in the radial distribution function, decreases with increasing x from 0<or = x< or = 1 and then increases with increasing x from 1< or = x< or = 5. However, structural correlations beyond the nearest neighbor atoms rapidly decrease with increasing Li content above x=1.5. A modest lattice expansion due to intercalated Li is inferred from the observed increase in the V-O radial distribution peak position, from 1.93 Angstroms at x=O (in agreement with x-ray diffraction results) to 2.02 Angstroms at x=5. Variable temperature 7Li NMR linewidth and spin-lattice relaxation measurements demonstrate that, at all concentrations studied (0.5< or = x< or = 6) the Li ions are relatively immobile, even at 200 deg. Centigrade. At low Li concentrations (up to x=1.5) the Li ions tend to reside near V(+5) sites rather than paramagnetic V(+4) or V(+3) sites.

Descriptors :   *SPECTROSCOPY, *MAGNETIC RESONANCE, *X RAY ABSORPTION ANALYSIS, *LITHIUM COMPOUNDS, IONS, SPATIAL DISTRIBUTION, STRUCTURAL PROPERTIES, X RAY DIFFRACTION, OXIDATION, OXIDES, SYMMETRY, BUTYL RADICALS, SOLID STATE PHYSICS, DISTRIBUTION FUNCTIONS, ELECTRON PARAMAGNETIC RESONANCE, VANADIUM, POLYCRYSTALLINE, RADIAL FLOW.

Subject Categories : Inorganic Chemistry
      Physical Chemistry
      Electricity and Magnetism
      Atomic and Molecular Physics and Spectroscopy

Distribution Statement : APPROVED FOR PUBLIC RELEASE