Intervalence charge transfer and electronic transport in molten salts containing tantalum and niobium complexes of mixed valency

Stöhr, U.; Freyland, W.

doi:10.1039/a904648h

Cited by 34 publications

(25 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The use of a carbon anode further reduces the cell voltage for Ca 2+ reduction by lowering the anodic discharging potential of the O 2− ion to form CO or CO 2 . The occurence of Ca 2+ reduction lowers the current efficiency not only as a side-reaction (if its product is not consumed by reaction with the oxide on the cathode), but also by increasing the electronic conductivity of the molten salt through the dissolved Ca (0) species, or through the electron hoping mechanism: A Ca (I) + B Ca (II) A Ca (II) + B Ca (I) [22] where the front-subscripts A and B denote the relative positions of the species in the melt. Note that theses species can be linked via disproportionation, i.e.…”

Section: Current and Energy Efficiencymentioning

confidence: 99%

Extraction of titanium from different titania precursors by the FFC Cambridge process

Wang

et al. 2006

Journal of Alloys and Compounds

121

View full text Add to dashboard Cite

Section: Current and Energy Efficiencymentioning

confidence: 99%

Extraction of titanium from different titania precursors by the FFC Cambridge process

Wang

et al. 2006

Journal of Alloys and Compounds

121

View full text Add to dashboard Cite

“…A remaining challenge to the FFC-Cambridge process for titanium extraction is the lower current efficiency. This can be ascribed partly to electronic conduction in the molten salt, due to dissolved calcium metal in CaCl 2 at less than unit activity 54,55,[60][61][62] and the presence of redoxactive impurities, 63 although the latter can be largely removed by pre-electrolysis. Further understanding is still required to overcome these obstacles and it is anticipated that by careful control of the electrolysis conditions, the energy consumption and current efficiency should reach 12.5 kWh/kg and 50% to achieve 2000 ppm oxygen.…”

Section: Towards Higher Efficiency For Titanium Extractionmentioning

confidence: 99%

Development of the Fray-Farthing-Chen Cambridge Process: Towards the Sustainable Production of Titanium and Its Alloys

Dolganov

et al. 2017

JOM

View full text Add to dashboard Cite

“…The dependence of the current plateau on voltage also suggests electronic conduction through the molten salt. [15] Upon electrolysis, the Tb 4 O 7 pellet quickly turned metallic on the surface (Figure 2 b), and the interior changed from dark brown to white (Figure 2 c). In some cases, a yellowish interlayer was seen (Figure 2 c), which was confirmed by XRD analysis as TbOCl (Figure 3 c) produced by the reaction Tb 2 O 3 + CaCl 2 Q 2 TbOCl + CaO.…”

mentioning

confidence: 98%

Electrochemical Metallization of Solid Terbium Oxide

et al. 2006

View full text Add to dashboard Cite

Heavy rare-earth (HRE) metals function very efficiently in advanced materials for magnetooptical-information storage, giant magnetostrictive energy conversion, and high-strength permanent magnets.[1] A 7 % annual growth in global demand for rare-earth (RE) metals was recently predicted. [2] Although the separation of mixed RE compounds has been greatly refined, [3] extraction of pure RE metals, especially the heavy ones, remains a historical challenge. The difficulty is multifold but particularly related to the high oxygen affinity of HRE metals. Current industrial methods convert HRE oxides into fluorides (e.g. by reaction with HF or NH 4 F), from which the metal is extracted by calciothermic reduction at % 1500 8C in argon.[4] The obtained HRE metal needs further separation from excess calcium under vacuum and deoxygenation by special methods.[5] HRE metals have high melting points (> 1350 8C), and hence cannot be extracted as a liquid in the same way as aluminum and light RE metals. [6] Electrodeposited solid reactive metals from molten salts are always dendritic and absorb oxygen easily when exposed to air. Dendrite formation may be avoided by deposition onto a suitable transition-metal substrate to form a liquid alloy, [7] but the alloy composition is difficult to control precisely.Recently, solid TiO 2 , [8] SiO 2 , [9] and some mixed oxides [10] were electrochemically reduced to the respective solid metals or alloys in molten salts. The new process requires that 1) the metal oxides to be reduced are thermodynamically less stable than the oxide of the metal element of the molten salt used, [8][9][10][11][12][13] and 2) electrodeposition of the metal of the molten salt should be avoided.[8] CaO is extremely stable, and hence molten CaCl 2 is the preferred choice for the new process. However, HRE oxides are almost as stable as CaO, and their reduction may not occur at potentials more positive than that[*] Dr.

show abstract

Intervalence charge transfer and electronic transport in molten salts containing tantalum and niobium complexes of mixed valency

Cited by 34 publications

References 13 publications

Extraction of titanium from different titania precursors by the FFC Cambridge process

Extraction of titanium from different titania precursors by the FFC Cambridge process

Development of the Fray-Farthing-Chen Cambridge Process: Towards the Sustainable Production of Titanium and Its Alloys

Electrochemical Metallization of Solid Terbium Oxide

Contact Info

Product

Resources

About