Back in the late 19^th century, germanium was another of those elements that, along with the likes of gallium and rhenium, the Russian chemist Dmitri Mendeleev predicted when he constructed the periodic table but, at the time, had yet to be "discovered."

Indeed, it would be nearly 20 years before the German scientist Clemens Winkler isolated the element (no. 32) in 1886, and named it after his homeland - Germany.

At first, Winkler had great difficulty trying to determine the element's atomic weigh - vital to determining its placement in Mendeleev's periodic table. Winkler dispatched samples to Paul Emile Lecoq de Boisbaudran, the discoverer of gallium (see Gallium: A Slippery Metal) for analysis, because of Boisbaudran's expertise in spectroscopy. Boisbaudran came up with the figure of 72.32, sufficiently close to Mendeleev's predicted figure of 72. Winkler was on the money!

Why Is Germanium Important?

Along with tellurium and antimony (see Antimony: A Metal?), germanium (Ge), as an element, displays the characteristics of both a metal and a nonmetal. However, to look at, pure germanium is hard, brittle, gray-white and shiny metal.

Germanium is of particular importance in both fiber-optic and infrared optical systems. Indeed, these are its main uses both in the U.S. and worldwide.

* Phosphors, Metallurgy & Chemotherapy

Source: U.S. Geological Survey (USGS)

In the U.S., however, the metal is not used in polymerization (PET) catalysts.

U.S. Germanium Usage - 2008

Main Uses

Fiber-Optic Systems: Because of its low optical dispersion and high refractive index (1.7) germanium dioxide (GeO₂), or germania, is used extensively as an additive (usually < 4% by weight) to the silicon dioxide (SiO₂) in the core of optical fibers. As a dopant, its usage is not restricted to any particular types of optical fiber; it is used in both single-mode (long distance) optical fibers and multimode (short distance) fibers.

Infrared Optics: One of the special characteristics of germanium is that it is transparent to near infrared (IR) (1,600-18,000nm) radiation, both as a metal and in oxide glass form. As a result, in the same way that ordinary glass is used to make lenses and windows for visible light, so can germanium be used for IR radiation.

Such lenses and windows are of particular use in military applications; for example, in search, detection, navigation and target evaluation systems. Since IR optical systems are affected neither by light levels nor prevailing weather conditions, they are ideal in such environs as the deserts of Iraq during a sandstorm or the rugged and dusty mountains of Afghanistan.

Indeed, IR sighting systems are currently used extensively not only in such Unmanned Aerial Vehicles (UAVs) as the Reaper (Predator B) or the RQ-4 Global Hawk surveillance aircraft, but also in the heat-seeking missiles they fire. On the ground, IR optical systems are used in binoculars, night-vision goggles and rifle-mounted scopes.

Nonmilitary use of IR optical technology is to be found both in advanced firefighting equipment and, again, in night-vision goggles. It is also used in satellite mapping and medical diagnostics. (The germanium isotope, germanium 68, is used in calibration sources for positron emission tomography (PET) scanners in hospitals and medical clinics.) And a use that cuts across both the civilian and military worlds is in the detection of nuclear radiation.

Electronics & Solar Applications: Germanium, used as a substrate, is of particular use in space-based solar cells (in 2007 at least, they accounted "for more than 80% of satellite applications") and other solar power arrays.

However, whereas in 1980, some 25% of the germanium used in the U.S. went into semiconductors, now the amount that does is negligible. There is, however, renewed interest in using it again to make semiconductors. The metal can still be found, though, both in power rectifiers and low-voltage power supplies.

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