Gallium is in group 13 of the periodic table and thus has similarities to the other elements in the group, aluminum (Al), indium (In), and thallium (Tl). Gallium does not occur as a free element in nature, but as gallium compounds in trace amounts in zinc and copper ores. Elemental gallium is a soft, silvery-white metal at room temperature.
Isotopes of Gallium
Gallium has several non-essential isotopes (at least ten), either because they are not produced in significant quantities or because they decay quickly. The three stable, natural isotopes are gallium-69, gallium-71, and gallium-73. However, the creative properties of gallium rely on its ability to be able to isotopically undergo radioactive decay, resulting in gallium-72, gallium-74, and gallium-76.
Gallium can be alloyed with a variety of metals to actively modify their properties and create specialized applications such as thermal and electrical conductivity modifiers for copper alloys. Gallium readily combines with most elements to form binary compounds, and it is only less reactive than the Group 13 elements.
For several years, Russia was the largest producer of purified gallium. Its share of world production reached 80% by 1980. However, in recent decades, China has emerged as the dominant supplier of refined gallium, supplying nearly all of the metal used by U.S. chipmakers for the production of electronic devices.
Gallium arsenide (GaAs), indium gallium arsenide (InGaAs), and gallium nitride (GaN) are all examples of compound semiconductors in which gallium can be alloyed with other elements such as arsenic or nitrogen. GaN is an III/V direct bandgap material that finds application in blue-light-emitting diodes (LEDs).
Uses of Gallium
Gallium is used for commercial light-emitting diodes, laser pointers, and optical amplification. Gallium arsenide phosphide (GaAsP) contains gallium(III) with arsenic, which is used to form optical fibers. Gallium phosphide (GaP) is used in laser diodes for optical storage and Blu-ray technology. Gallium, like gallium nitride (GaN), is an important semiconductor material that has recently emerged to serve critical roles in solid-state lighting (SSL) and power electronics applications.
Gallium(III) chloride (NaCl) and gallium(III) bromide (GaBr) are used for GaAs and GaN semiconductor epitaxy. Gallium is used as an agent of reducing macro-bubbles during the crystal growth of silicon by gas expansion in rapid solidification or pulling processes. Non-radioactive isotopes are used in the treatment of liver cancer and gallium-67 is used for gallium scanning.
Gallium is used in thermometers as a substitute for mercury and to detect infrared radiation, particularly in night vision equipment such as cameras and goggles. The radioactive isotope Ga emits soft gamma rays, which can be measured by scintillators made with a phosphor-containing a rare-earth element such as europium. Gallium is typically alloyed with indium to lower its melting point below that of pure gallium to improve the manufacturability of the metal.