Element of the day: Germanium
In Dmitri Mendeleev's original periodic table, he predicted the existence of germanium. He believed it to have a molecular weight of 70 g/mol (? = 70 in the figure). This is very similar to germanium's actual molecular weight of 72.63 g/mol.
Discovery of Germanium
Located at atomic number 32 of the periodic table is this week's Element of the Day — germanium. Germanium was discovered in 1886 by the German chemist Clemens Winkler. He named this element in honor of his home country. Winkler had received a sample of ore from a silver mine near Freiberg, Germany. He found that this ore contained 75% silver, 18% sulfur, and the remaining 7% was made of an unknown substance. Earlier in 1869, Dmitri Mendeleev (creator of the original periodic table) predicted that an element must exist between silicon and tin. He described the properties of this new element, which Mendeleev named ekasilicon, and it exactly matched that of Winkler's mysterious substance. The discovery of germanium helped establish Mendeleev's period table as one of the most important scientific discoveries of all time.
Application of Germanium as a Semiconductor
A semiconductor is a material that has an electrical conductivity value falling between that of a conductor and an insulator. In other words, it is a material that only partly conducts current. The first semiconductor devices ever created were made from germanium. Although in recent years silicon has dominated the field of semiconductor electronics, germanium has made a comeback due to its extensive use in solar panels. Sunlight falling on these germanium semiconductor junctions generates useful electrical current that increases the efficiency when compared to using silicon.
Lenses of night-vision goggles made of germanium awaiting recycling.
Germanium's major use today is in fiber optics, which uses thin flexible fibers of glass or other transparent solids to transmit light signals between the two ends of the fiber. Optical fibers allow for transmission over longer distances than electrical cables. These fibers are used instead of metal wires because the signals travel along them with less loss and are immune to electromagnetic interference. About 35% of germanium produced is used in the cores of fiber optic cables, where its high refractive index (describes the velocity of light in a specific medium) and low optical dispersion (keeps the light collimated, or parallel to each other) makes it an ideal material. Optical fibers are doped with germanium oxide to help them keep laser signals reflecting inside. The laser that burns data onto a writable DVD utilizes germanium in the process. Germanium is also completely transparent at infrared wavelengths, making it extremely useful in the optics of devices like night-vision goggles. Germanium in these goggles converts the infrared image into a visible image.
Ingesting small quantities of germanium is not hazardous. Some foods like garlic, vegetables, and grains actually contain small amounts of it. Oddly, germanium has been sold as a nutritional supplement in the USA and Japan. In the late-1900s, it was believed that germanium would act as an elixir to diseases like cancer and AIDS. Studies demonstrated that these germanium tablets can have detrimental effects on the human body when taken for a prolonged amount of time. Some of these effects included kidney failure, nerve damage, and in rare cases even death. Bizarrely, germanium is still commonly used in bath salts for medicinal purposes in Japan. Despite these odds uses of germanium today, we have it to thank for many of the various technological advancements that came about during the 20th century.
