After a somewhat complicated history of discovery, the Swedish chemist Christian Wilhelm Blomstrand finally isolated metallic niobium in 1864. It is formally named for the Greek mythological figure Niobe, although its original name, columbium, is still occasionally used.
Niobium is a soft, grey, lustrous, ductile transition metal. It has a low density in comparison to other refractory metals. Furthermore, it is corrosion resistant and exhibits superconductivity properties; however, both properties are strongly dependent on the purity of the niobium metal.
Niobium is primarily obtained from the mineral pyrochlore, most of which is mined and processed in Brazil and to a lesser extent in Canada. Other mineral sources include the tantalum bearing mineral columbo-tantalite, or what is referred to as ‘coltan.’ Most of the pyrochlore that is mined is converted to a niobium-iron alloy known as ferro-niobium and serves as the start point for most of its applications.
Applications of Niobium:
- Steel Production: Niobium is an effective micro alloying element for steel that improves the grain refining and precipitation hardening of the steel, thereby increasing the toughness, strength, formability and weld-ability. These alloy steels are widely used as structural components in modern automobiles and pipeline construction.
- Super Alloys: Niobium is used in nickel, cobalt and iron-based super alloys for applications in jet engine components, gas turbines, rocket subassemblies and heat resisting and combustion equipment.
- Electronics: Niobium has a high dielectric constant and is thus able to hold and store electrical charges. The most effective capacitors are those made of tantalum, but high tantalum prices have led to the substitution of niobium in many non-critical applications where ambient temperatures are low.
- Superconducting Magnets: Niobium has the largest magnetic penetration depth of any element. As such, niobium-tin and niobium-titanium alloys are used as wires for superconducting magnets capable of producing exceedingly strong magnetic fields. These superconducting magnets are used in magnetic resonance imaging (MRI) and nuclear magnetic resonance instruments. They are also used in the construction of particle accelerators such as the Large Hadron Collider which uses 600 metric tons of superconducting wire strands.
- Numismatics: Niobium is used as a precious metal in commemorative coins and jewellery, often with silver or gold. The colour in these coins, ranging from blue, green, brown, purple, violet or yellow, is created by diffraction of light through a thin oxide layer produced by anodizing of the niobium surface.
- Other Uses: Niobium is used in medical devices such as pacemakers, as niobium is physiologically inert and thus hypoallergenic. Niobium-doped glass has a high refractive index: a property of use to the optical industry in making thinner corrective glasses.