Gallium
Discovered in 1875 by the French chemist Paul-Émile Lecoq de Boisbaudran, and named after Gaul (the Roman name for France), gallium was a predicted metal. Its discovery was a milestone in chemistry and validated Dmitri Mendeleev’s Periodic Table of the Elements.
Gallium is one of a handful of metals, along with mercury, cesium and rubidium, that is liquid at room temperature. Pure gallium metal has a brilliant silvery color and as a solid metal fractures like glass.
Gallium is normally a by-product of the manufacture of aluminum. The purification of bauxite by the Bayer process produces an alkaline solution, which can - through a series of electrolytic processes -result in liquid gallium metal. It can also be recovered during the smelting process of some zinc ores.
Applications of Gallium:
- Electronic and Electromotive: Gallium nitride (GaN) and gallium arsenide (GaAs) are semiconductors and appear in compounds used in light-emitting diodes (LEDs). GaN emits blue light in LEDs and is a key component in blue laser devices. Other applications include transistors, the manufacture of ultra-high speed logic chips and low-noise microwave preamplifiers. It has been suggested that a liquid gallium-tin alloy could be used to cool computer chips in place of water.
- Energy: Gallium can be used in a compound to produce thin film solar panels, as an efficient alternative to crystalline silicon. An aluminum-gallium alloy can potentially provide a solid hydrogen source for transportation purposes: effectively a hydrogen fuel cell.
- Medical technologies: Gallium citrate and gallium nitrate are used as radiopharmaceutical agents in a nuclear medicine imaging procedure commonly referred to as a gallium scan. Furthermore, Gallium-68 has been used as an experimental positron emitting gallium isotope, in a PET scan technique which combines features of the gallium scan and the CT/PET scan. Gallium nitrate is also used as an intravenous pharmaceutical to treat hypercalcemia associated with tumor metastasis to bones. Gallium maltolate is used in clinical and preclinical trials as a potential treatment for cancer, infectious disease and inflammatory diseases. Research is being conducted to determine whether gallium can be used to fight bacterial infections in people with cystic fibrosis.
- Industrial Products: Gallium readily alloys with most metals, and has been used as a component in low-melting temperature alloys and added in quantities up to 2% in common solders can aid their wetting and flow characteristics.
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