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Title: Aqueous citrato-oxovanadate(IV) precursor solutions for VO2: synthesis, spectroscopic investigation and thermal analysis
Authors: PEYS, Nick
DE DOBBELAERE, Christopher
De Gendt, Stefan
VAN BAEL, Marlies
Issue Date: 2014
Citation: DALTON TRANSACTIONS, 43 (33), p. 12614-12623
Abstract: An aqueous precursor solution, containing citrato-VO2+ complexes, is synthesized for the formation of monoclinic VO2. With regard to the decomposition of the VO2+ complexes towards vanadium oxide formation, it is important to gain insights into the chemical structure and transformations of the precursor during synthesis and thermal treatment. Hence, the conversion of the cyclic [V4O12](4-) ion to the VO2+ ion in aqueous solution, using oxalic acid as an acidifier and a reducing agent, is studied by (51)Vanadium nuclear magnetic resonance spectroscopy. The citrate complexation of this VO2+ ion and the differentiation between a solution containing citrato-oxalato-VO2+ and citrato-VO2+ complexes are studied by electron paramagnetic resonance and Fourier transform infra-red spectroscopy. In both solutions, the VO2+ containing complex is mononuclear and has a distorted octahedral geometry with a fourfold R-CO2- ligation at the equatorial positions and likely a fifth R-CO2- ligation at the axial position. Small differences in the thermal decomposition pathway between the gel containing citrato-oxalato-VO2+ complexes and the oxalate-free gel containing citrato-VO2+ complexes are observed between 150 and 200 degrees C in air and are assigned to the presence of (NH4)(2)C2O4 in the citrato-oxalato-VO2+ solution. Both precursor solutions are successfully used for the formation of crystalline vanadium oxide nanostructures on SiO2, after thermal annealing at 500 degrees C in a 0.1% O-2 atmosphere. However, the citrato-oxalato-VO2+ and the oxalate-free citrato-VO2+ solution result in the formation of monoclinic V6O13 and monoclinic VO2, respectively.
Notes: Van Bael, MK (reprint author),[Peys, Nick; Gielis, Sven; Peeters, Ellen; De Dobbelaere, Christopher; Hardy, An; Van Bael, Marlies K.] Hasselt Univ, Inst Mat Res Inorgan & Phys Chem, Diepenbeek, Belgium. [Peys, Nick; De Gendt, Stefan] IMEC VZW, Heverlee, Belgium. [Adriaensens, Peter] Hasselt Univ, Inst Mat Res Appl & Analyt Chem, Diepenbeek, Belgium. [Van Doorslaer, Sabine] Univ Antwerp, Dept Phys, BIMEF Lab, B-2020 Antwerp, Belgium. [Gielis, Sven; Hardy, An; Van Bael, Marlies K.] IMEC VZW, Div IMOMEC, Diepenbeek, Belgium. [De Gendt, Stefan] KULeuven, Lab Phys & Analyt Chem, Heverlee, Belgium. marlies.vanbael@uhasselt.be
URI: http://hdl.handle.net/1942/17181
DOI: 10.1039/c4dt01346h
ISI #: 000340353100020
ISSN: 1477-9226
Category: A1
Type: Journal Contribution
Validation: ecoom, 2015
Appears in Collections: Research publications

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