Vanadium sesquioxide

Metallic V203 at the lowest temperatures can be stabilized by pressures of 23 kbar or by the addition of Ti203. The most striking property of the metallic phase at low temperatures is the high linear specific heat yT, with y—96 x 10 4calK 2mol 1 (McWhan et al 1971), and the high Pauli 

At higher temperatures the observed entropy change at the transition (AS=2.6 eu) at 1 atm is nearly equal to y Tc (Tc =150 K). Although the value of S should be somewhat less than that given by S=y T, because the specific heat is not necessarily linear, there can be no doubt that a major part of the entropy is electronic. 

The magnetic susceptibility is also very high (Menth and Remeika 1970) the density of states deduced from the specific heat, and that deduced from the susceptibility, are in the ratio 

The magnetic behaviour of V203 and of the Ti-doped alloys is shown in Fig. 6.6. It can be seen that the susceptibility is higher in the metallic than the non-metallic phase. The drop in the susceptibility with temperature above about 

100 K suggests a very high effective mass, or a Fermi energy for the carrier of the order kBT, where T= 300-600 K. 

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Va.na.dlum(III) Oxide. Vanadium(III) oxide (vanadium sesquioxide, V2O2) is a black soHd, having the comndum (AI2O2) stmcture. It can be prepared by reduction of the pentoxide by hydrogen or carbon. Air oxidation proceeds slowly at ambient temperatures, but oxidation by chlorine at elevated temperatures to give VOCl and V20 is rapid. 

Let the calciothermic reduction of vanadium sesquioxide (V203), according to the following overall reaction, be considered ... 

Vanadium forms numerous oxides, the most important of which are vanadium monoxide, vanadium sesquioxide, vanadium dioxide and vanadium pentoxide. In the earlier examples (e.g., oxides of chromium and of niobium) the enthalpy values for the aluminothermic reduction of each of the oxides was given for the purpose of illustration. Normally, the consideration can be restricted to only those oxides which are readily obtained and which can be handled freely without any special or cumbersome precautions. In the case of vanadium for example, it is sufficient to consider the reduction of the sesquioxide (V203) and the pentoxide (V2Os). The pertinent reactions are ... 

The fluorination of vanadium sesquioxide (V203) to vanadium trifluoride (VF3) can be carried out by using fluorine ... 

Ammonium hydrogen fluoride (NH4HF2) is useful for converting pure oxides or hydroxides to the corresponding fluorides. The reaction occurs through the formation of a double fluoride. For example, with vanadium sesquioxide the following reactions occur ... 

Figures 7 and 8 show that the linear decay predicted by Equation (10) is followed consistently by the two catalysts, A and C. The rule of linear decay was followed with 11.8% and 7,9% of average deviation for catalysts A and C, respectively. For calculating a, the rate of decay in (10), values of s 1,95 and pvc 4,72 g/cu,cm. were taken. The latter is the density of vanadium sesquioxide (S3V2) which Is usually considered the prevalent product in the vanadium deposit.

VANADIUM SESQUIOXIDE (1314-34-7) OjV2 On exposure to air it is gradually converted into vanadimn tetraoxide may self-ignite in hot air. Material is a chemical base. Incompatible with calcium, chlorine, lithimn and halogenated conq)ounds such as chlorine trifluoride. 

Vanadium Trioxide. Vanadium sesquioxide vanadic oxide. OjV2 mo] wt 149.90. V 67.98%, O 32.02%. VjOj, Prepd by reduction of V20, with hydrogen or carbon monoxide. 

Before proceeding to consider kinetic equations and implied reaction mechanisms, we may note some other pertinent features of these reactions. (A) Benzene hydrogenation was subject to the influence of the Strong Metal-Support Interaction (Section 3.35) when titania and vanadium sesquioxide were used as supports for rhodium, platinum and iridium - even Pt/Si02 and Ni/Si02 when heated... 

Vanadium pentoxide (dust) Vanadium pentoxide (fume) Vanadium pentoxide, nonfused. See Vanadium pentoxide Vanadium sesquioxide. See Vanadium trioxide Vanadium tetrachloride CAS 7632-51-1 EINECS/ELINCS 231-561-1 UN 2444 (DOT)... 

Synonyms Vanadic oxide Vanadium oxide Vanadium sesquioxide... 

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