PMID- 17508089
OWN - NLM
STAT- MEDLINE
DCOM- 20070917
LR  - 20131121
IS  - 1463-9076 (Print)
IS  - 1463-9076 (Linking)
VI  - 9
IP  - 20
DP  - 2007 May 28
TI  - Theoretical and experimental determination of the electronic structure of 
      V(2)O(5), reduced V(2)O(5-x) and sodium intercalated NaV(2)O(5).
PG  - 2564-76
AB  - In this work the electronic structure of V(2)O(5), reduced V(2)O(5-x) 
      (V(16)O(39)) and sodium intercalated NaV(2)O(5) has been studied by both 
      theoretical and experimental methods. Theoretical band structure calculations 
      have been performed using density functional methods (DFT). We have investigated 
      the electron density distribution of the valence states, the total density of 
      states (total DOS) and the partial valence band density of states (PVBDOS). 
      Experimentally, amorphous V(2)O(5) thin films have been prepared by physical 
      vapour deposition (PVD) on freshly cleaved highly oriented pyrolytic graphite 
      (HOPG) substrates at room temperature with an initial oxygen understoichiometry 
      of about 4%, resulting in a net stoichiometry of V(2)O(4.8). These films have 
      been intercalated by sodium using vacuum deposition with subsequent spontaneous 
      intercalation (NaV(2)O(5)) at room temperature. Resonant V3p-V3d photoelectron 
      spectroscopy (ResPES) experiments have been performed to determine the PVBDOS 
      focusing on the calculation of occupation numbers and the determination of 
      effective oxidation state, reflecting ionicity and covalency of the V-O bonds. 
      Using X-ray absorption near edge spectra (XANES) an attempt is made to visualize 
      the changes in the unoccupied DOS due to sodium intercalation. For comparison 
      measurements on nearly stoichiometric V(2)O(5) single crystals have been 
      performed. The experimental data for the freshly cleaved and only marginally 
      reduced V(2)O(5) single crystals and the NaV(2)O(5) results are in good agreement 
      with the calculated values. The ResPES results for V(2)O(4.8) agree in principle 
      with the calculations, but the trends in the change of the ionicity differ 
      between experiment and theory. Experimentally we find partly occupied V 3d states 
      above the oxygen 2p-like states and a band gap between these and the unoccupied 
      states. In theory one finds this occupation scheme assuming oxygen vacancies in 
      V(2)O(5) and by performing a spin-polarized calculation of an antiferromagnetic 
      ordered NaV(2)O(5.).
FAU - Laubach, Stefan
AU  - Laubach S
AD  - Eduard-Zintl-Institut fur Anorganische und Physikalische Chemie, Technische 
      Universitat Darmstadt, Petersenstrasse 21, D-64287 Darmstadt, Germany.
FAU - Schmidt, Peter C
AU  - Schmidt PC
FAU - Thissen, Andreas
AU  - Thissen A
FAU - Fernandez-Madrigal, Francisco Javier
AU  - Fernandez-Madrigal FJ
FAU - Wu, Qi-Hui
AU  - Wu QH
FAU - Jaegermann, Wolfram
AU  - Jaegermann W
FAU - Klemm, Matthias
AU  - Klemm M
FAU - Horn, Siegfried
AU  - Horn S
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20070321
PL  - England
TA  - Phys Chem Chem Phys
JT  - Physical chemistry chemical physics : PCCP
JID - 100888160
RN  - 0 (Intercalating Agents)
RN  - 0 (Oxides)
RN  - 0 (Vanadium Compounds)
RN  - 9NEZ333N27 (Sodium)
SB  - IM
MH  - Intercalating Agents/*chemistry
MH  - Models, Molecular
MH  - Molecular Conformation
MH  - Oxidation-Reduction
MH  - Oxides/*chemistry
MH  - Photons
MH  - Sodium/chemistry
MH  - Spectrum Analysis
MH  - Thermodynamics
MH  - Vanadium Compounds/*chemistry
EDAT- 2007/05/18 09:00
MHDA- 2007/09/18 09:00
CRDT- 2007/05/18 09:00
PHST- 2007/05/18 09:00 [pubmed]
PHST- 2007/09/18 09:00 [medline]
PHST- 2007/05/18 09:00 [entrez]
AID - 10.1039/b612489e [doi]
PST - ppublish
SO  - Phys Chem Chem Phys. 2007 May 28;9(20):2564-76. doi: 10.1039/b612489e. Epub 2007 
      Mar 21.