What Is Germanium?
Germanium is a grayish-white, hard, brittle solid.
Germanium’s element symbol is Ge, its atomic number is 32, and its CAS number is 7440-56-4. It is classified as a “semimetallic element,” a substance intermediate between metals and nonmetals. It is a substance extracted from ores and soil in nature and was discovered by the German scientist Winkler in 1885. It is classified as a rare metal because only about 0.00014% of it exists on the earth and its mining is limited.
Germanium compounds can be broadly classified into two types: organic and inorganic germanium compounds.
Uses of Germanium
1. Inorganic Germanium
Inorganic germanium, such as germanium oxide, is used as an industrial raw material for diodes, transistors, infrared lenses for night vision cameras, optical fibers, catalysts in the manufacture of PET bottles, health accessories such as bracelets, and germanium hot baths. Germanium oxide, with its high refractive index and low optical dispersion, is particularly useful as a dopant in the core of wide-angle cameras, microscopes, and optical fibers. Germanium can be alloyed with silicon, and circuits that take advantage of the heterojunction properties of germanium and silicon are fast, making silicon-germanium alloys an important semiconductor material for high-speed integrated circuits. In addition, semiconductor detectors made of single-crystal high-purity germanium are utilized in airport security to detect radiation sources.
2. Organic Germanium
While inorganic germanium is insoluble in water and accumulates in the body, causing harm, organic germanium is mainly used in health foods and cosmetics because it is water soluble and is also found in plants known to be good for the body, such as ginseng and aloe.
Properties of Germanium
Germanium has a melting point of 937°C and a boiling point of 2,850°C. It exists as a solid at room temperature, and its density in the solid state is 5.35 g/cm3. It is insoluble in dilute acids and alkalis, but slowly dissolves in hot concentrated sulfuric and nitric acids, and reacts violently with molten alkalis to form germanates ([GeO4]4-). It has a narrower band gap (0.7eV) than silicon, making it a useful semiconductor element.
Structure of Germanium
Germanium has three different crystal structures, depending on temperature and pressure. At room temperature and pressure, it has a cubic structure similar to diamond, called α-germanium, and at higher pressures, it has a tetragonal structure similar to β-Tin, called β-germanium. There is also a structure called germanene, which is created by a process similar to graphene, using a high vacuum and high temperature to deposit layers of germanium atoms on a substrate, and is considered a material that exhibits more abundant physical properties than graphene.
Other Information on Germanium
1. How Germanium Is Produced
Germanium is produced primarily from sphalerite but is also found in silver, lead, and copper ores. Germanium in ores is mostly sulfides, which are converted to oxides by heating them under air (GeS2+3O2→GeO2+2SO2). High-purity germanium oxide can be reduced with hydrogen (GeO2+2H2→Ge+2H2O) to yield products suitable for infrared optics and semiconductor manufacturing, while reduction with coke (GeO2+C→Ge+CO2) yields products for steel production and industrial products.
2. Legal Information
Germanium is not subject to any of the major laws and regulations, such as the Poisonous and Deleterious Substances Control Law, the Fire Service Law, and the Pollutant Release and Transfer Register Law (PRTR Law).
3. Handling and Storage Precautions
Handling and storage precautions are as follows
- Seal the container tightly and store it in a dry, cool, and dark place.
- Use only outdoors or in well-ventilated areas.
- Avoid contact with strong oxidizing agents.
- Wear protective gloves and glasses when using.
- Wash hands thoroughly after handling.
- In case of skin contact, rinse immediately with water.
- In case of eye contact, rinse cautiously with water for several minutes.