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Usage

Uses

Used in Ferrous Metallurgy:
Niobium is used as an alloying agent in stainless steels and metals for welding rods. It is also used in niobium base alloys for high temperatures and nuclear reactions. Niobium has some use as a getter in electronic vacuum tubes.
Used in Nonferrous Metallurgy:
Niobium is used as an additive in the manufacture of most high-strength, low-alloy carbon steels and microalloyed steels that are used in the construction of oil and gas pipelines, bridges, buildings, concrete bars, and automobiles. It is also added to nickeland cobalt-based superalloys and is a component of zirconium, titanium, and tungsten alloys.
Used in Electronic and Propulsion Devices:
Niobium is used in electronic and propulsion devices, in electrodes, catalysis, vacuum tubes, and high-pressure sodium vapor lamps.
Used in Superconductivity:
Niobium has special cryogenic properties, allowing it to withstand very cold temperatures and improve its ability to conduct electricity. This characteristic makes it an excellent metal for low-temperature electrical superconductors. Niobium alloyed with germanium becomes a superconductor of electricity that does not lose its superconductivity at 23.2° Kelvin as large amounts of electrical current are passed through it. In the pure metallic state, niobium wires are also superconductors when the temperatures are reduced to near absolute zero (–273°C). Niobium alloys are also used to make superconductive magnets and jewelry.
Used in High-Temperature Engineering Products:
Niobium sputtering target is used in high-temperature engineering products. It is also used as an alloying agent for certain steels where it greatly improves the strength of the resulting material. Niobium finds applications in atomic reactors due to its corrosion resistance, and when combined with either tin (Nb3Sn) or zirconium, it has a high degree of superconductivity.

History

The element was discovered in 1801 by British chemist Charles Hatchett during analysis of a black mineral sample from the British Museum, originally sent in 1753 from Connecticut. He named the element columbium, after the country of its origin, Columbia (United States). In 1844, Rose announced the discovery of a new element which he named as niobium, in honor of Niobe, the daughter of Tantalus, the mythological Goddess of Tears. Later, it was established that Hatchett’s columbium and Roses’ niobium were the same element. Both names remained in use for more than one hundred years. In 1949 at the Fifteenth International Union of Chemistry Congress held at Amsterdam, the name niobium was officially adopted as the international name. Niobium was prepared in the metallic state for the first time by Blomstrand in 1866, later by Moissan, and still later, by Goldschmidt. While Blomstrand reduced niobium chloride with hydrogen to form niobium, Moissan and Goldschmidt reduced the oxide with carbon (in an electrical furnace) and aluminum powder, respectively. Niobium occurs naturally in several minerals, mostly associated with tantalum and many rare earth elements. The metal is never found in free elemental form. It occurs mostly as hydroxide, silicate, or borate or as its oxy salt, niobate, which is mostly associated with isomorphous tantalate. The principal niobium minerals are pyrochlore, loparite, and koppite all of which contain titanium together with calcium and other metals, such as cerium. They are complex hydroxide minerals and their composition may vary with place. Another type of niobium mineral is the niobates-tantalates mixed ores of Nb2O6—Ta2O6 or of compositions (Nb,Ta)2O6. Such ores usually contain iron and sometimes manganese which partially replaces iron. A typical example is an isomorphous admixture of Fe(NbO3)2—Fe(TaO2)2. Many impurity metals, such as tungsten, titanium, and tin are also found in these ores. The abundance of niobium in the earth’s crust is estimated to be in the range 20 mg/kg and its average concentration in sea water is 0.01 mg/L. The metal also is found in the solar system including the lunar surface. Radionucleides niobium-94 and -95 occur in the fission products of uranium- 235.

History

Niobium was discovered in 1801 by Hatchett in an ore sent to England more that a century before by John Winthrop the Younger, first governor of Connecticut. The metal was first prepared in 1864 by Blomstrand, who reduced the chloride by heating it in a hydrogen atmosphere. The name niobium was adopted by the International Union of Pure and Applied Chemistry in 1950 after 100 years of controversy. Most leading chemical societies and government organizations refer to it by this name. Some metallurgists and commercial producers, however, still refer to the metal as “Niobium.” Niobium is found in niobite (or columbite), niobite-tantalite, pyrochlore, and euxenite. Large deposits of niobium have been found associated with carbonatites (carbon-silicate rocks), as a constituent of pyrochlore. Extensive ore reserves are found in Canada, Brazil, Congo-Kinshasa, Rwanda, and Australia. The metal can be isolated from tantalum, and prepared in several ways. It is a shiny, white, soft, and ductile metal, and takes on a bluish cast when exposed to air at room temperatures for a long time. The metal starts to oxidize in air at 200°C, and when processed at even moderate temperatures must be placed in a protective atmosphere. It is used in arc-welding rods for stabilized grades of stainless steel. Thousands of pounds of niobium have been used in advanced air frame systems such as were used in the Gemini space program. It has also found use in super-alloys for applications such as jet engine components, rocket subassemblies, and heat-resisting equipment. The element has superconductive properties; superconductive magnets have been made with Nb-Zr wire, which retains its superconductivity in strong magnetic fields. Natural niobium is composed of only one isotope, 93Nb. Forty-seven other isotopes and isomers of niobium are now recognized. Niobium metal (99.9% pure) is priced at about 50￠/g.

Production Methods

There are several processes for extracting and refining niobium from its ores. The process of choice depends on nature of the ore and end use intended for the metal. Some common steps in these recovery processes involve ore preconcentration, breaking or opening the ore, obtaining pure niobium compounds, reduction of niobium compounds to niobium metal, purification or refining metal and fabrication. If niobium is extracted from a niobium-tantalum ore, the most important step is separation of niobium from tantalum, both of which are chemically very similar. Ferroniobium can be produced from the ore pyrochlore in batch process by thermal reduction in a refractory-lined steel or preferably an electric furnace reactor. Aluminum powder is used as a reducing agent. Ore-opening is a key step in the recovery of niobium, and separation of niobium from tantalum and impurity metals is the most important step in its extraction from the ore. It may be achieved by several methods that include solvent extraction, ion exchange, fractional crystallization, fractional sublimation, and other techniques. High purity grade metal may be produced by reduction of niobium pentaoxide, Nb2O5 or pentachloride, NbCl5 at elevated temperatures ranging from 1400 to 2000°C and often under vacuum using various reducing agents, such as carbon, hydrogen, sodium and other substances: Nb2O5 + 7C → 2NbC + 5CO Nb2O5 + 5NbC → 7Nb + 5CO 2NbCl5 + 5H2 → 2Nb + 10HCl NbCl5 + 5Na → Nb + 5NaCl

Production Methods

Theextractingandre?ningprocessesforniobiumfromore are extremely complex and consist of a series of operations, starting from upgrading the ores by concentration. Disruption of the niobium-containing matrix is then performed by an ore-opening procedure with hot HF or fusion with alkali ?uxes. The next steps include pure niobium compound preparation and reduction to metallic niobium, followed by re?ning, consolidation, and fabrication of the metal. Niobium is so closely associated with tantalum that they must be separated by fractional crystallization or by solvent extraction before puri?cation.

Isotopes

There are 49 isotopes of niobium, ranging from Nb-81 to Nb-113. All are radioactiveand made artificially except niobium-93, which is stable and makes up all of theelement’s natural existence in the Earth’s crust.

Origin of Name

Niobium is named after the Greek mythological figure Niobe who was the daughter of Tantalus. Tantalus was a Greek god whose name is the source of the word “tantalize,” which implies torture: he cut up his son to make soup for other gods.

Characteristics

Some of niobium’s characteristics and properties resemble several other neighboring elementson the periodic table, making them, as well as niobium, difficult to identify. This isparticularly true for tantalum, which is located just below niobium on the periodic table.Niobium is not attacked by cold acids but is very reactive with several hot acids such ashydrochloric, sulfuric, nitric, and phosphoric acids. It is ductile (can be drawn into wiresthrough a die) and malleable, which means it can be worked into different forms.

Hazard

Niobium is not considered reactive at normal room temperatures. However, it is toxic in itsphysical forms as dust, powder, shavings, and vapors, and it is carcinogenic if inhaled or ingested.

Carcinogenicity

No evidence was found that niobiumiscarcinogenic.Indeed,therearesomestudiessuggesting its antitumor activity. In the mouse study of Schroeder et al., occurrence of 23.6% of tumors in the niobiumtreated group (5–6.62ppm niobium in drinking water and diet for a lifetime) versus 34.8% for the controls was documented.

InChI:InChI=1/Nb