- α-VOSO4:A 2D-ferromagnet
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A reexamination of the magnetic behavior of vanadyl sulfate α-VOSO4 shows that the main magnetic interaction occurs within the layers through |SO42-| anions. The exchange constant is found to be positive (J/k = + 1.5 K) involving ferromagnetic couplings in contrast to vanadyl phosphates which exhibit nearly the same geometry but whose exchange interactions are antiferromagnetic. An explanation is proposed, taking into account both bond angles and nature of the counterion.
- Lezama, L.,Villeneuve, G.,Marcos, M. D.,Pizarro, J. L.,Hagenmuller, P.
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- Phase ratios in the K2O-V2O4-SO 3 system at high sulfur trioxide concentrations
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Phase ratios in the three-component oxide system K2O-V 2O4-SO3 in the region of the sulfur trioxide concentrations corresponding to its concentrations in the active component of vanadium catalysts for SO2/
- Krasil'nikov
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p. 258 - 262
(2008/10/09)
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- Lithium electrochemical intercalation in β-VOSO4
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A new low-temperature route for β-VOSO4 synthesis is proposed, involving reduction in sulphuric acid in the presence of sulphur. Lithium intercalation has been performed on this material, both chemically and electrochemically and the compounds have been characterized by XRD as well as IR and Raman spectroscopy. From potentio-dynamic and galvano-static electrochemical studies it is shown that intercalation occurs in two steps, firstly with a structural change at 2.84 V vs. Li metal, then in a solid solution domain. The process appears partly reversible and the system is shown to present a good cycling behavior on almost 0.6 e- per transition metal. From these results it appears that the energy of redox transition metal couples involving VO2+ structural units in octahedral coordination is between those observed in oxides and in M2(XO4)3 (X = S, P, As) compounds, respectively.
- Gaubicher,Chabre,Angenault,Lautie,Quarton
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