Atomic Number: 41
Atomic Symbol: Nb
Atomic Weight: 92.90638
Melting Point: 4,491 F (2,477 C)
Boiling Point: 8,571 F (4,744 C)
Word origin: Niobium is named after Niobe, the daughter of Tantalus in Greek mythology, who turned to stone while weeping for her slain children.
Discovery of niobium
Niobium has a convoluted history. John Winthrop discovered an ore in Massachusetts in 1734 and sent it to England. The mineral sat in the British Museum collection for years until it was analyzed in 1801 by Charles Hatchett. He discovered a new element in the ore and named it columbium after Columbia, the poetic name for America. In 1809, William Hyde Wollaston, an English chemist compared columbite with another mineral, tantalite, and declared that columbium was actually the element tantalum. The two elements are very similar, are always found together and are difficult to isolate.
In 1844, Heinrich Rose, working with samples of columbite and tantalite, produced two new separate, but very similar, acids, which he named niobic acid and pelopic acid. He renamed the element niobium. Twenty years later, Swiss chemist Jean Charles Galissard de Marignac isolated metallic niobium by heating the chloride in a hydrogen atmosphere.
The element was called columbium (symbol Cb) in the United States for about 100 years, while it was called niobium in Europe. In 1949, the International Union of Pure and Applied Chemistry compromised and officially adopted niobium as the element’s name, in deference to European usage. In turn, the union accepted tungsten rather than wolfram as the name for Element No. 74 (which still carries the symbol W), in deference to American usage. Many metallurgists and metal societies, however, still refer to niobium as columbium.
Properties of niobium
Niobium is a shiny, white, soft and ductile transition metal. It takes a bluish cast when exposed to air at room temperature for an extended period of time. It starts to oxidize in air at 200 C (392 F). When processed, it must be placed in a protective atmosphere at moderate temperatures.
There are 18 known isotopes of niobium.
Sources of niobium
Niobium can be isolated from tantalum and prepared several different ways.
Niobium is found in niobite (or columbite), parochlore, niobite-tantalite and euxenite. As a constituent of parochlore, large amounts of niobium have been found associated with carbonatites (carbon-silicate rocks). Extensive mineral deposits are found in Canada, Brazil, Nigeria, Zaire and Russia.
Uses of niobium
Niobium has superconductive properties and it has been useful in making superconductive magnets in the form of niobium-zirconium (Nb-Zr) wire, which retains its superconductivity in strong magnetic fields. There is hope that Nb-Zr wire could direct large-scale power generation.
Niobium is also used arc-welding rods for stabilized grades of stainless steel. Thousands of pounds of niobium have been used in air frame systems, including in the Gemini space program.
Niobium is also commonly used in making jewelry.