Niobium. Symbol Nb, atomic number 41 and atomic weight 92.906. In the United States this element was originally called columbium. The metal industry and metallurgists still use this old name.
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- 1 Use
- 2 Features
- 3 Health effects
- 4 Environmental effects
- 5 Uses
- 6 Sources
Most of the niobium is used in specialty stainless steels, high-temperature alloys, and superconducting alloys such as Nb3Sn. Niobium is also used in nuclear batteries.
It is very inert to all acids, except hydrofluoric, supposedly because it has an oxide film on the surface. Metallic niobium oxidizes slowly in alkaline solution. Reacts with oxygen and halogens hot to form halides and oxide in oxidation state V, with nitrogen to form NbN and with carbon to form NbC, as well as with other elements such as arsenic, antimony, tellurium and selenium.
The oxide Nb2O5, which melts at 1520º (2768ºF), dissolves in molten alkali to form a soluble complex niobate, Nb6O198-. Normal niobates, including NbO43-, are insoluble. The oxide dissolves in hydrofluoric acid to produce ionic species such as NbOF52- and NbOF63-, depending on the concentration of the fluoride and hydrogen ions. The largest fluorinated complex that can exist in solution is NbF6-.
Niobium, when inhaled, is retained primarily in the lungs, and secondarily in the bones. It interferes with calcium as an activator of the enzyme system. In laboratory animals, inhalation of niobium nitride or pentoxide results in scarring of the lungs at exposure levels above 40 mg / m3.
No negative environmental effects have been documented.
The most important application is as an alloying element for the construction of machines and high pressure gas pipelines. It is also used in superalloys, to withstand temperatures above 650 ° C, for example, in jet aircraft turbines and automobile exhaust pipes . It is usually part of electronic ceramics and photographic lenses.
In the field of electrical superconductivity, it is used in alloys with titanium to build supercooled electromagnets used in nuclear magnetic resonance. It has recently been used as a building block for experimental quantum computers.
In the field of organometallic chemistry, there are numerous uses that have been given to it. For example, niobocene sandwich complexes are capable of activating CH bonds, serve as models in olefin polymerization processes, and even exhibit cytotoxic activity against cancer cells.