Oxofluoride Complexes of Niobium(IV,V) in the Liquid Eutectic LiF-NaF-KF Melt at 700 degrees C with Varying Oxide-to-Niobium Molar Ratios.

Electrochemical Studies of the Molten System K[sub 2]NbF[sub 7]-Na[sub 2]O-Nb-(LiF-NaF-KF)[sub eut] at 700°C

“…This implies that both the NbOF y (yϪ2)Ϫ and NbO 2 F y yϪ complexes form in the melt, in agreement with the data of Matthiesen et al 17 The reason the reduction/oxidation of the Nb(IV)oxofluoro complexes is observed only as a shoulder in the cyclic voltammogram in Fig. 11 is that the potential for the reduction…”

“…Precipitation of a solid compound, probably AlkNbO 3 , as indicated by Eq. 10, seems to occur, in agreement with Matthiesen et al 17 and the voltammetric studies…”

“…They show that the nominal solubilities of Nb 2 O 5 and KNbO 3 are 1.8 and 0.13 mol %, respectively. Matthiesen et al, 17 using chemical analysis of melt samples extracted from a FLINAK melt at 700ЊC, found the same solubilities. Figure 11 shows a cyclic voltammogram of a FLINAK melt to which 1 mol % K 2 NbF 7 , excess Nb metal, and 0.9 mol % Na 2 O were added.…”

“…The analysis of the samples was performed with inductively coupled plasma (ICP) for Nb and the carbothermal-reduction technique using LECO TC-436 for oxide in the melt. 17 The experimental procedure has been published elsewhere. 17 The electrochemical techniques involved cyclic voltammetry, linear sweep voltammetry, staircase Various voltammetric methods have been used to study FLINAK (LiF-NaF-KF eutectic melt 46.5-11.5-42 mol %) melts containing about 1 mol % niobium-fluoro and -oxofluoro complexes with Nb in oxidation states (V) and (IV) at 700ЊC and varying amounts of Na 2 voltammetry, and square wave voltammetry.…”

“…17 The experimental procedure has been published elsewhere. 17 The electrochemical techniques involved cyclic voltammetry, linear sweep voltammetry, staircase Various voltammetric methods have been used to study FLINAK (LiF-NaF-KF eutectic melt 46.5-11.5-42 mol %) melts containing about 1 mol % niobium-fluoro and -oxofluoro complexes with Nb in oxidation states (V) and (IV) at 700ЊC and varying amounts of Na 2 voltammetry, and square wave voltammetry. These methods are available through the use of a computer-controlled potentiostat/galvanostat model M273, Princeton Applied Research.…”