niobiums

Niobium, chemical symbol Nb and atomic number 41, is a soft, ductile transition metal in group 5 of the periodic table. It is silver-gray and has good resistance to corrosion due to a stable oxide layer. Niobium has a high melting point, about 2,477°C, and a relatively high density of 8.57 g/cm3 at room temperature.

Niobium occurs naturally with tantalum in minerals such as columbite and tantalite, collectively known as coltan. Because of their coexistence, niobium is often produced as a byproduct of tantalum mining. Historically the element was called columbium; the name niobium was adopted in the mid-20th century, and the symbol Nb is retained in IUPAC usage.

Key applications of niobium include steel alloying, where small additions improve strength, toughness, and weldability, particularly in high-strength low-alloy steels and pipeline steels. In superconductivity, niobium forms alloys such as NbTi and Nb3Sn that are used in magnets for MRI machines and particle accelerators. Niobium is also used in jewelry because it is hypoallergenic and can form colorful oxide surfaces; niobium oxide is used in specialty glass and coatings.

World production concentrates in Brazil, Canada, Australia, and several African countries. Ore concentrates of Nb2O5 are refined to metallic niobium, typically through reduction and purification, after which the metal is cast into ingots or formed into alloys.

Natural niobium consists of a single stable isotope, Nb-93; several radioactive isotopes have been produced for research purposes but have no commercial use. The niobium industry is subject to standard occupational safety practices for handling metals and powders.