0000000000528213

AUTHOR

Virginie Nivoix

showing 2 related works from this author

Intermediate valencies of vanadium cations appearing during oxidation of vanadium–iron spinels

2000

Abstract The oxidation state of vanadium cations in nanosized vanadium–iron spinels at stoichiometry and at oxidative nonstoichiometry has been investigated by associating X-ray diffraction, thermal analysis (DSC), infrared and X-ray photoelectron spectroscopies. It has been established that, during oxidation, the V3+ cations present several intermediate valencies before to realize the final oxidation state +5. A comparison was made with the oxidation of V2O3.

Valence (chemistry)X-ray photoelectron spectroscopychemistryInfraredOxidation stateInorganic chemistryVanadiumchemistry.chemical_elementGeneral Materials ScienceCondensed Matter PhysicsSpectroscopyThermal analysisStoichiometryMaterials Chemistry and Physics
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Mechanical activation conditions of the Fe2O3 and V2O3 mixture powders in order to obtain a nanometric vanadium spinel ferrite

1999

Abstract Co-milling of iron and vanadium oxides allows to obtain an intimate oxides mixture at a nanoscale, similar to a coprecipitate elaborated by soft chemistry. Reduction of such a mixture in the same temperature and oxygen partial pressure conditions (500°C and 10−25 Pa) as the soft chemistry products leads to a nanometric vanadium ferrite with the only spinel phase. The characterization of the powders is achieved by X-ray diffraction (XRD), scanning electron microscopy, infrared (IR) spectrometry, thermogravimetry and calorimetry. Homogeneity of grain size and chemical composition is reached if the initial oxides have similar grain size.

Materials scienceGeneral Chemical EngineeringSpinelMineralogyVanadiumchemistry.chemical_elementPartial pressureengineering.materialGrain sizeSoft chemistryThermogravimetrychemistryChemical engineeringengineeringFerrite (magnet)Chemical compositionPowder Technology
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