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P2-Na(x)VO(2) system as electrodes for batteries and electron-correlated materials.
MedLine Citation:
PMID:  23142842     Owner:  NLM     Status:  Publisher    
Layered oxides are the subject of intense studies either for their properties as electrode materials for high-energy batteries or for their original physical properties due to the strong electronic correlations resulting from their unique structure. Here we present the detailed phase diagram of the layered P2-Na(x)VO(2) system determined from electrochemical intercalation/deintercalation in sodium batteries and in situ X-ray diffraction experiments. It shows that four main single-phase domains exist within the 0.5≤x≤0.9 range. During the sodium deintercalation (intercalation), they differ from one another in the sodium/vacancy ordering between the VO(2) slabs, which leads to commensurable or incommensurable superstructures. The electrochemical curve reveals that three peculiar compositions exhibit special structures for x  =  1/2, 5/8 and 2/3. The detailed structural characterization of the P2-Na(1/2)VO(2) phase shows that the Na(+) ions are perfectly ordered to minimize Na(+)/Na(+) electrostatic repulsions. Within the VO(2) layers, the vanadium ions form pseudo-trimers with very short V-V distances (two at 2.581 Å and one at 2.687 Å). This original distribution leads to a peculiar magnetic behaviour with a low magnetic susceptibility and an unexpected low Curie constant. This phase also presents a first-order structural transition above room temperature accompanied by magnetic and electronic transitions. This work opens up a new research domain in the field of strongly electron-correlated materials. From the electrochemical point of view this system may be at the origin of an entire material family optimized by cationic substitutions.
Marie Guignard; Christophe Didier; Jacques Darriet; Pierre Bordet; Erik Elkaïm; Claude Delmas
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-11-11
Journal Detail:
Title:  Nature materials     Volume:  -     ISSN:  1476-1122     ISO Abbreviation:  Nat Mater     Publication Date:  2012 Nov 
Date Detail:
Created Date:  2012-11-12     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101155473     Medline TA:  Nat Mater     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
CNRS, Université de Bordeaux, ICMCB site de l'ENSCBP-IPB, 87 avenue du Dr. A. Schweitzer, 33608 Pessac Cedex, France.
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