Xi:Irritant;7440-62-2Relevant articles and documents
Reduction of vanadium from alkaline solutions
Shirinov,Gasanly,Ganbarov
, p. 1230 - 1233 (2009)
Effect of the potential sweep rate and temperature on the reduction kinetics of vanadate ions from alkaline solutions was studied. The nature of polarization in separate regions of the cathodic process was determined.
The Preparation of Vanadium Tetrachloride from Vanadium Dichloride Oxide and Vanadium Trichloride and the Hydrogen Reduction Process of Vanadium Tetrachloride
Yajima, Akimasa,Matsuzaki, Ryoko,Saeki, Yuzo
, p. 2843 - 2846 (1980)
The reactions of VCl2O and VCl3 with chlorine, and the reaction of VCl3O, formed by the chlorination of VCL2O, with chlorine in the presence of carbon were examined.The products formed by the reaction between gaseous VCl4 and hydrogen at various temperatures, and the behavior of VCl3 and VCl2 on heating in a hydrogen stream were examined.The reaction between VCl2O and chlorine occurs above ca. 120 deg C and proceeds markedly above ca. 170 deg C to form VCl3O.VCl4 can be obtained by passing the gaseous VCl3O together with chlorine through a carbon bed held at ca. 700 deg C.The reaction between VCl3 and chlorine occurs above ca. 80 deg C and proceeds markedly above ca. 170 deg C to form VCl4.The hydrogen reduction process of VCl4 in the vapor phase may be represented as follows: The reaction between VCl4 and hydrogen, 2VCl4(g) + H2(g) -> 2VCl3(s) + 2HCl(g), proceeds above ca. 500 deg C to form VCl3.Subsequently, the hydrogen reduction of the VCl3, 2VCl3(s) + H2(g) -> 2VCl2(s) + 2HCl(g), and the disproportionation of the VCl3, 2VCl3(s) -> VCl4(g), proceed to form VCl2.Above ca. 620 deg C, the reaction between the VCl2 and hydrogen, VCl2(s) + H2(g) -> V(s) + 2HCl(g), proceeds to form vanadium.
Preparation of vanadium nitride and its subsequent metallization by thermal decomposition
Tripathy, P. K.,Arya, A.,Bose, D. K.
, p. 175 - 180 (1994)
The preparation of high purity (greater than 99.8%) ductile grade vanadium is extremely difficult owing to its exceptionally high affinity towards carbon, nitrogen and oxygen. The removal of these interstitial impurities by conventional melt-refining routes is rather difficult. Specialized techniques such as pyrovacuum treatment, iodide decomposition and fused salt electrorefinement are normally adopted to prepare ultrapure vanadium. In the present investigation a new technique which involves the preparation and subsequent thermal decomposition of vanadium nitride (VN) has been attempted to obtain vanadium metal. The vanadium nitride in this study was prepared by carbonitrothermic reduction of vanadium pentoxide (V2O5) at a temperature of 1500 °C. The VN thus formed was thermally decomposed at 1750 °C under reduced pressure (3×10-2 Pa) to metallic vanadium. Consolidation of the product metal sponge (by arc melting) under a low pressure, high purity argon atmosphere yielded vanadium of purity better than 97%. The arc-melted metal can be further refined by fused salt electrolysis, leading to a purity better than 99.5%.
Extreme Sensitivity of a Topochemical Reaction to Cation Substitution: SrVO2H versus SrV1- xTixO1.5H1.5
Amano Patino, Midori,Zeng, Dihao,Blundell, Stephen J.,McGrady, John E.,Hayward, Michael A.
, p. 2890 - 2898 (2018)
The anion-ordered oxide-hydride SrVO2H is an antiferromagnetic insulator due to strong correlations between vanadium d electrons. In an attempt to hole-dope SrVO2H into a metallic state, a strategy of first preparing SrV1-xTixO3 phases and then converting them to the corresponding SrV1-xTixO2H phases via reaction with CaH2 was followed. This revealed that the solid solution between SrVO3 and SrTiO3 is only stable at high temperature. In addition, reactions between SrV0.95Ti0.05O3 and CaH2 were observed to yield SrV0.95Ti0.05O1.5H1.5 not SrV0.95Ti0.05O2H. This dramatic change in reactivity for a very modest change in initial chemical composition is attributed to an electronic destabilization of SrVO2H on titanium substitution. Density functional theory calculations indicate that the presence of an anion-ordered, tetragonal SrMO2H phase is uniquely associated with a d2 electron count and that titanium substitution leads to an electronic destabilization of SrV1-xTixO2H phases, which, ultimately, drives further reaction of SrV1-xTixO2H to SrV1-xTixO1.5H1.5. The observed sensitivity of the reaction products to the chemical composition of initial phases highlights some of the difficulties associated with electronically doping metastable materials prepared by topochemical reactions.
Reaction of the intermetallide ZrV2 with ammonia
Fokin,Fokina,Tarasov
, p. 21 - 23 (2012)
The reaction of the intermetallic compound ZrV2 with ammonia within a temperature range of 150-500°C in the presence of NH4Cl as an activator of the process was studied. Depending on the reaction temperature, intermetallide hydrides and compositions of metal hydrides and nitrides or metal nitrides were obtained in the form of finely dispersed powders with particle sizes of less than 1.0 μm. Pleiades Publishing, Ltd., 2012.
Some novel tetradentate Schiff base complexes VO(IV) and Cu(II) involving fluorinated heterocyclic β-diketones and polymethylene diamines of varying chain length : Synthesis, spectral, coordination and thermal aspects
Modi,Thaker
, p. 567 - 577 (2008)
The present article describes the synthesis, spectral, coordination and thermal aspects of N,N'-polymethylene bis(1-phenyl-3-methyl-4- trifluoroacetylimino-2-pyrazoline-5-ol)oxovanadium(IV) or copper(II) Schiff base complexes with alkyl backbones ranging
Mechanistic insight into the influence of Al2O3 concentration on the electro-reduction of V2O3 to vanadium in molten Na3AlF6
Kong, Yapeng,Chen, Jianshe,Li, Binchuan,Liu, Kuiren,Han, Qing
, p. 452 - 460 (2019)
The influence of Al2O3 concentration on the direct electrochemical reduction of porous vanadium sesquioxide precursors in molten Na3AlF6 was investigated by constant voltage electrolysis and cyclic voltammetry. The products obtained by electrolysis at various Al2O3 concentrations were examined by XRD and SEM. Specifically, the morphologies of the outer metal layer initially formed were characterized by SEM and EDS, also their effects on the electrolysis process were systematically studied. The results indicate that the Al2O3 concentration in molten Na3AlF6 has a significant impact on the reduction process. When 0.5 mass% Al2O3 is added into molten Na3AlF6, the reduction rate of V2O3 can be improved because of the appropriate increase of aluminium reductant and relatively high oxide ion transfer rate. However, a high Al2O3 concentration (1.0–3.0 mass%) causes the massive precipitation of aluminium at cathodic outer metal layer and further forms Al–V alloy, causing the densification of the outer metal layer and hampering the reduction reaction kinetics.
VCl4 revisited: ESR and photolysis in solid hydrogen, neon, and argon; Formation of VH4
Graham, John T.,Li, Li,Weltner Jr.
, p. 9302 - 9306 (2000)
Electron-spin-resonance (ESR) spectra of the VCl4 molecule were observed at low concentrations at 2-4 K in solid H2, D2, Ne, and Ar. As previously observed in other matrixes, the spectra of an axial molecule were obtained in H2, D2, and Ne, indicative of a Jahn-Teller (JT) distorted molecule with compressed tetrahedral D2d symmetry. However, in argon, a composite of an axial and a near-isotropic spectrum was observed, and annealing yielded only the isotropic at 4 K. This surprising result is discussed relative to JT dynamic vibronic interaction. Photolysis of VCl4 in H2 (and D2) matrixes yielded a new spectrum assigned to VH4 (or VD4), indicating that the tetrahydride is also a JT-distorted 2E ground-state molecule, in accord with earlier ab initio theory.
Synthesis, spectral, thermal and insulin-enhancing properties of oxovanadium(IV) complexes of metformin Schiff-bases
Mahmoud, Marwa A.,Zaitone, Sawsan A.,Ammar, Alaa M.,Sallam, Shehab A.
, p. 957 - 969 (2017/04/11)
A series of VO2+ complexes of Schiff-bases of metformin with each of salicylaldehyde (HL1); 2,3-dihydroxybenzaldehyde (H2L2); 2,4-dihydroxybenzaldehyde (H2L3); 2,5-dihydroxybenzaldehyde (H2L4); 3,4-dihydroxybenzaldehyde (H2L5); and 2-hydroxynaphthaldehyde (HL6) were synthesized by template reaction. The new compounds are characterized through elemental analysis, conductivity measurements, magnetic moment, IR, UV–Vis, ESR and mass spectroscopy. The complexes have square pyramidal structure with μ values of pentacoordinated vanadyl ion. TG, DTG and DTA confirm the proposed stereochemistry, and a mechanism of thermal decomposition was suggested. Mice treated with the complexes [VOL1H2O]·1?H2O and [VOHL4H2O]·2H2O showed glucose-lowering effect of 59.31, 58.79% (20?mg?kg?1) and 64.98, 74.8% (40?mg?kg?1) compared to metformin.
LiAlD4 with VCl3 additives: Influence of ball-milling energies
Blanchard,Lem,?vergaard,Brinks,Hauback
, p. 467 - 473 (2009/02/02)
The reduction reaction of VCl3 mixed with LiAlD4 is studied for different ball-mill energies. From low to high ball-milling energies VCl3 is reduced by the formation of Li-V-Cl metastables phases, LiCl and free Al and V or Al-V phases. It is also shown that the enhancement of the kinetics reaches a limit with increased ball-mill energy. From measurements of the released hydrogen with a Sieverts apparatus and X-ray and neutron diffraction, it is shown that even under mild conditions, at or close to room temperature, the two first steps of the decomposition of VCl3-enhanced LiAlD4 occurs during the first weeks after milling at temperatures in the range 20-50 °C.
