Vanadium trioxide

Vanadium trioxide, V2O3. Black powder (V2OS plus Hj under heat). Readily reoxidized to VjOj. Stable down to VO,.35. 

Phase transitions are involved in critical temperature thermistors. Vanadium, VO2, and vanadium trioxide [1314-34-7] V2O3, have semiconductors—metal transitions in which the conductivity decreases by several orders of magnitude on cooling. Electronic phase transitions are also observed in superconducting ceramics like YBa2Cu30y but here the conductivity increases sharply on cooling through the phase transition. 

Vanadium Carbide. Vanadium pentoxide [1314-62-17, V2O5, or vanadium trioxide [1314-34-7] VO3, are the most satisfactory oxides for the preparation of VC. Vanadium pentoxide is best prepared by igniting chemically pure ammonium vanadate [7803-55-6] NH VO, in the presence of moist oxygen to avoid reaction with nitrogen V2O3 is obtained by reduction of V2O3 with hydrogen (see Vanadium compounds). 

Dining outgassing of scrap uranium-aluminium cermet reactor cores, powerful exotherms led to melting of 9 cores. It was found that the incident was initiated by reactions at 350°C between aluminium powder and sodium diuranate, which released enough heat to initiate subsequent exothermic reduction of ammonium uranyl hexafluoride, sodium nitrate, uranium oxide and vanadium trioxide by aluminium, leading to core melting. 

Vanadium Subsilicide, V2Si, is obtained by fusing a mixture of vanadium trioxide, V2Os, and silicon, with the addition of either a large excess of vanadium or carbon or copper. The carbide or copper alloy produced is decomposed at the temperature employed.11 The silicide forms metallic prisms, of density 5-48 at 17° C., the m.pt. of which is higher than in the ease of the disilicide. It is attacked by the halogens, hydrogen chloride gas, and fused sodium or copper, but hydrochloric acid, nitric acid and sulphuric acid are without action. 

Vanadium Disilicide, VSia, is prepared by reducing a mixture of vanadium trioxide and silicon with magnesium vanadium pentoxide can also be employed with the addition of fluorspar to the mixture.12 Gin used a mixture of the pentoxide, silica, and coke.18 Vanadium disilicide is a very stable compound it forms metallic prisms which melt at 1655° C., have a specific gravity of 4-42, and are hard enough to scratch glass. It is attacked by hydrofluoric acid, hydrogen chloride gas, and fused alkalis. 

Oxides Vanadium monoxide VO, gray solid vanadium trioxide V2O3, black solid vanadium dioxide VO2, dark blue solid vanadium pentoxide V2O5, orange to red solid. The last is the most important oxide formed by the ignition in an of vanadium sulfide, 01 othei oxide, 01 vanadium used as a catalyzer, e.g., the reaction SO2 gas plus oxygen of air to form sulfur tnoxide. and the oxidation of naphthalene by air to form phthalie anhydride. 

SYNS POTASSIUM METAVANADATE POTASSIUM VANADIUM TRIOXIDE V.ANADIC ACID, POTASSIUM SALT... 

SYNS VANADIC OXIDE VANADIUM OXIDE VANADIUM TRIOXIDE... 

POTASSIUM TRIIODIDE see PLW285 POTASSIUM TROCLOSENE see PLDOOO POTASSIUM, metal aUoys pN 1420) pOp see PKT250 POTASSIUM VANADIUM TRIOXIDE see PLK810 POTASSIUM ZINC CHROMATE see PLW500 POTASSIUM ZINC CHROMATE see CMK400 POTASSIUM ZINC CHROMATE FIYDROXIDE see PLW500... 

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