skip to main content

Title: VO{sub 2} (A): Reinvestigation of crystal structure, phase transition and crystal growth mechanisms

Well crystallized VO{sub 2} (A) microrods were grown via a single step hydrothermal reaction in the presence of V{sub 2}O{sub 5} and oxalic acid. With the advantage of high crystalline samples, we propose P4/ncc as an appropriate space group at room temperature. From morphological studies, we found that the oriented attachment and layer by layer growth mechanisms are responsible for the formation of VO{sub 2} (A) micro rods. The structural and electronic transitions in VO{sub 2} (A) are strongly first order in nature, and a marked difference between the structural transition temperatures and electronic transitions temperature was evidenced. The reversible intra- (LTP-A to HTP-A) and irreversible inter- (HTP-A to VO{sub 2} (M1)) structural phase transformations were studied by in-situ powder X-ray diffraction. Attempts to increase the size of the VO{sub 2} (A) microrods are presented and the possible formation steps for the flower-like morphologies of VO{sub 2} (M1) are described. - Graphical abstract: Using a single step and template free hydrothermal synthesis, well crystallized VO{sub 2} (A) microrods were prepared and the P4/ncc space group was assigned to the room temperature crystal structure. Reversible and irreversible phase transitions among different VO{sub 2} polymorphs were identified and their progressive nature wasmore » highlighted. Attempts to increase the microrods size, involving layer by layer formation mechanisms, are presented. - Highlights: • Highly crystallized VO{sub 2} (A) microrods were grown via a single step hydrothermal process. • The P4/ncc space group was determined for VO{sub 2} (A) at room temperature. • The electronic structure and progressive nature of the structural phase transition were investigated. • A weak coupling between structural and electronic phase transitions was identified. • Different crystallite morphologies were discussed in relation with growth mechanisms.« less
Authors:
 [1] ;  [2] ;  [3] ;  [1] ;  [2] ;  [4] ;  [5] ;  [1] ;  [2] ;  [1] ;  [2]
  1. ICMCB, CNRS, UPR 9048, F-33608 Pessac (France)
  2. (France)
  3. (Romania)
  4. CeCaMA, University of Bordeaux 1, ICMCB, 87 Avenue du Dr. A. Schweitzer, F-33608 Pessac (France)
  5. National Institute for Research and Development in Electrochemistry and Condensed Matter, Timisoara, Plautius Andronescu Str. No. 1, 300224 Timisoara (Romania)
Publication Date:
OSTI Identifier:
22334203
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 213; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CRYSTAL GROWTH; CRYSTAL STRUCTURE; ELECTRONIC STRUCTURE; HYDROTHERMAL SYNTHESIS; OXALIC ACID; PHASE TRANSFORMATIONS; SPACE GROUPS; TRANSITION TEMPERATURE; VANADIUM OXIDES; X-RAY DIFFRACTION; X-RAY PHOTOELECTRON SPECTROSCOPY