Niobium trichloride

Niobium Trichloride, NbCl3, is prepared by leading the vapour of niobium pentachloride through a heated tube.4 It is also formed in small quantity by the action of carbon tetrachloride vapour on niobium pentoxide contained in a hard-glass tube, and has probably been prepared in solution by the electrolytic reduction of the pentachloride.4 It forms a black, crystalline crust with an almost metallic lustre, which closely resembles the appearance of a film of sublimed iodine. It is not decomposed by water or ammonia, but is readily oxidised by dilute nitric add to niobium pentoxide. On being heated to a red heat in an atmosphere of carbon dioxide, a sublimate of niobium oxytrichloride, NbOCl3, is produced, the carbon dioxide undergoing reduction to the monoxide. 

NaAISI206 JADEITE 1134 NbOCI3 NIOBIUM TRICHLORIDE OXIDE 1176... 

NaAISI206[D] DEHYDRATED ANALCITE 1134 NbOCI3[g] NIOBIUM TRICHLORIDE OXIDE (GAS) 1177... 

Roscoe discovered tungsten pentachloride and pentabromide, uranium pentachloride,2 and niobium trichloride (which he found gave NbOClg and CO when heated in COg). He determined the vapour densities of PbClg and TlCl, showed that Delafontaine s supposed new rare-earth metal philippium is a mixture of yttrium and terbium, and redetermined the atomic weight of carbon (C = 12 002). Roscoe published several papers and a book on spectrum analysis. 

This is accomplished by raising the temperature to between S00°C and SSO°C, and the reaction is carried out in several glass or silica tubes. Horizontal silica tubes, 10 ft long by 7 in. diameter, have been used, packed with lengths of thin glass tubing to provide an adequate surface area for plating out of the niobium trichloride product. 

Schafer, H. Niobium trichloride—a compound with a large extension of phase. Angew. Chem. 67, 748 (1955). 

Niobium metal powder has been produced by the reduction of the relatively inert black solid, niobium trichloride, in a current of hydrogen, i.e. 

The process has the disadvantage of being dependent upon a slow reaction and also is unfortunately affected by side reactions. Niobium trichloride disproportionates at temperatures near 1000°C, with the production of a mixture of niobium metal and higher chlorides. The latter have been reported as the tetrachloride and pentachloride,23 with the former preponderating, i.e. 

The higher chlorides are volatile and reduce directly in hydrogen, depositing both niobium metal and niobium trichloride on the walls of the furnace tube, away from the reaction trays. Besides the inconvenience of this mass transfer effect, the niobium metal powder deposited from reduction of the gaseous higher chlorides tends to be very finely divided and therefore pyrophoric on exposure to air. Nevertheless, the product of the trichloride reduction reaction, has been handled satisfactorily, and has given ductile massive metal on sintering. 

The product was satisfactory except for a high iron content. This was believed to arise from the reaction of the niobium pentachloride vapour with the metallic iron of the reactor, away from the crucible. A deposit of niobium trichloride was produced on the reactor wall and ferric chloride entered the vapour phase. From here it was fed to the magnesium along with the niobium pentachloride, to take part in the reaction and allow iron to enter the product. A reactor made from nickel-plated steel was partially successful in reducing the iron content, but the nickel was relatively easily separated from the steel at reactor temperatures. It was expected that a reactor made entirely of solid nickel would have given satisfactory results, vapour-phase corrosion of the nickel itself being reasonably low. 

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