Germanium was discovered in 1886 by the German chemist Clemens Winkler. Almost ten years earlier, the Russian chemist Dmitri Ivanovich Mendeleev had predicted the existence of germanium, which would be homologous to silicon. Mendeleev called the then undiscovered element Eka-silicon. Winkler gave the element the name Germanium.

The poor availability of the element made further investigations difficult. Moreover, no technical applications were initially found for the rare non-metallic element.

Germanium only gained economic significance after 1945, when its properties as a semiconductor for electronics were recognized.

Many other substances are now also used as semiconductors, but germanium remains of great importance for the manufacture of transistors and components for devices such as rectifiers and photo cells.

About half of the germanium produced is used in fiber optics. Germanium dioxide is used to improve light transmission. Germanium is indispensable for high-speed internet, telecommunications, and data centers.

The second most important application, with a share of about 30 percent, is infrared optics (IR) and thermal imaging. Germanium lenses and windows are used in military night vision devices and thermal cameras. In the automotive industry, germanium is employed in driver assistance systems as well as in satellite imaging.

The use of germanium in semiconductors and electronics remains relevant but is declining. It is used in high-speed transistors, diodes, and solar cells. Silicon-germanium alloys (SiGe) improve the performance of 5G and mobile communication chips.

Germanium is obtained as a byproduct during the processing of zinc and coal. About 80 percent of the world’s produced germanium comes from zinc ore processing. The most important mineral for germanium extraction from zinc is sphalerite, the most significant zinc ore.

China is a major producer of germanium from coal sources. During coal combustion, germanium accumulates in fly ash, from which it is then recovered.

After China, which dominates global germanium production with 60 to 70 percent, Russia and Canada are other production countries.

The largest germanium producer in the world is the Chinese company Yunnan Germanium Industry, headquartered in Kunming, Yunnan Province.

Silicon or gallium arsenide replace germanium in certain electronic applications.

Some metal compounds can be substituted in high-frequency electronic applications and in some LED applications.

Chalcogenide glass has been used as a substitute for germanium metal in infrared applications.

Antimony and titanium are used as polymerization catalysts.

Elemental Germanium

Germanium is located in the periodic table among the metalloids but is classified as a semiconductor according to newer definitions. Elemental germanium is very brittle and highly stable in air at room temperature. Only when strongly heated (glowing) in an oxygen atmosphere does it oxidize to germanium(IV) oxide (GeO₂). GeO₂ is dimorphic and transforms at 1033 °C from the rutile modification (coordination number CN = 6) into the β-quartz structure (CN = 4). In powdered form, it is a flammable solid and can be easily ignited by a brief exposure to an ignition source and continues burning even after the source is removed. The ignition risk increases with finer particle size. In compact form, germanium is non-flammable.

Germanium exhibits oxidation states of +2 and +4, with germanium(IV) compounds being the most stable. It is resistant to attack by hydrochloric acid, potassium hydroxide, and diluted sulfuric acid. However, it dissolves in alkaline hydrogen peroxide solutions, concentrated hot sulfuric acid, and concentrated nitric acid, forming germanium dioxide hydrate.

According to its position in the periodic table, germanium’s chemical properties lie between those of silicon and tin.

Germanium is one of the few substances that exhibits the property of density anomaly: its density in the solid state is lower than in the liquid state. Its bandgap at room temperature is approximately 0,67 eV.

Gallium was discovered in 1875 by the French chemist Paul-Émile Lecoq de Boisbaudran. Earlier, the Russian chemist Dmitri Ivanovich Mendeleev had predicted the existence of an element that would lie between aluminum and indium in the periodic table. This then-undiscovered element was referred to as eka-aluminum. In honor of his homeland, Lecoq de Boisbaudran named his discovery gallium.

Gallium remained largely unnoticed for a long time because it could not be economically extracted from ores. Due to its poor availability and the resulting high price, interest in gallium and its chemistry was limited.

Interest in the element grew with the discovery of the semiconductor properties of gallium compounds.

In 2024, the estimated global consumption of gallium was around 600 tons per year. The main consumer is the electronics and semiconductor industry.

About three-quarters of the gallium is used for the production of gallium nitride (GaN) and gallium arsenide (GaAs) wafers. GaAs and GaN outperform silicon as semiconductor materials in terms of speed, heat resistance, and energy efficiency.

GaAs wafers are used in 5G and 6G mobile communication chips, satellite and radar systems, and in optoelectronics (LEDs, laser diodes, solar cells).

Fast chargers, inverters for electric vehicles, data centers, fiber optics, and defense systems such as radars use GaN semiconductors.

Smaller amounts of gallium are also used in medicine and research.

Gallium is produced as a byproduct of aluminum and zinc production. Therefore, bauxite and sphalerite are the most important minerals. China’s monopoly on gallium is particularly noticeable, as the country controls between 80 and 95 percent of global production. The leading gallium producers are China Germanium, a subsidiary of Yunnan Chihong Zinc & Germanium, and the state-owned aluminum company Chinalco.

Until 2015, the Germany-based company Ingal Stade was the largest gallium producer outside of China. However, the operation was shut down in 2016.

Liquid crystals made from organic compounds are used as a gallium substitute in LEDs for optical displays.

Complementary metal-oxide-semiconductor (CMOS) power amplifiers based on silicon compete with GaAs power amplifiers in mid-range third-generation (3G) mobile phones.

Indium phosphide components can replace GaAs-based infrared laser diodes in some applications with specific wavelengths, and helium-neon lasers compete with GaAs in applications with visible laser diodes.

Silicon is the main competitor to GaAs in solar cell applications.

In many defense-related applications, GaAs- and GaN-based circuits are used due to their unique properties, for which there are no effective substitutes.

Cobalt compounds have been used for thousands of years to give glazes and ceramics a blue color. They have been found in Egyptian statuettes and Persian necklace beads from the 3rd millennium BC, in glass artifacts in the ruins of Pompeii, and in China during the Tang Dynasty (618–907 AD) as well as later in the blue porcelain of the Ming Dynasty (1368–1644).

In the Middle Ages, miners considered these compounds valuable but cursed silver ores because they smelled like garlic during smelting due to their arsenic content and could not be reduced. These ores were therefore called kobolds, nickel, or wolf’s spit. In 1735, the Swedish chemist Georg Brandt succeeded in isolating the metal. He recognized it as a new element and named it cobalt.

Today, cobalt is primarily used in lithium-ion batteries, especially in electric vehicles, but also in smartphones, laptops, and other electronic devices. About 60 percent of cobalt demand comes from the battery sector. Electric cars are the main driver of increasing cobalt mining.

Cobalt is an important component of the cathode in lithium-ion batteries. The metal provides stability and a high energy density in the batteries, which is crucial for the range of electric vehicles.

Other applications of cobalt include superalloys for engines, gas turbines, and industrial machinery.

In combination with tungsten and carbon, cobalt forms a hard metal (e.g., tungsten carbide-cobalt), which is used in cutting tools, drills, and mining machinery.

Cobalt is also used in permanent magnets (e.g., aluminum-nickel-cobalt and samarium-cobalt magnets), which play an important role in motors, sensors, and wind turbines.

Furthermore, cobalt is used in catalysts, pigments for the production of paints, ceramics, and glass, as well as in very small amounts in medical products such as joint prostheses and dental alloys.

Cobalt ore is usually obtained as a byproduct during the mining of iron, nickel, copper, silver, manganese, zinc, and arsenic ores. The most important cobalt-containing minerals include cobaltite, heterogenite, spherocobaltite, erythrite, carrollite, and skutterudite, although these are relatively rare.
Currently, the largest amounts of cobalt come from the Central African “Copper Belt.”

About three-quarters of the world’s cobalt supply originates from the Democratic Republic of Congo (DRC), where the largest cobalt mines in the world—Tenke Fungurume and Kamoto—are located. The biggest producer of refined cobalt is China, which imports vast quantities of cobalt ore from the DRC.

Other important sources are sulfide deposits in Russia, Canada, and Australia. Recently, laterite ores in tropical regions such as Indonesia, the Philippines, and New Caledonia have gained in importance.

Indonesia is developing into another key country for cobalt mining.

Among the largest companies are the Chinese CMOC Group (China Molybdenum), operator of the Tenke Fungurume mine. The Swiss company Glencore follows in second place, owning the Kamoto and Mutanda mines in the DRC.

Approximately ten percent of cobalt demand is met through recycling.

Depending on the application, replacing cobalt can lead to performance losses or higher costs. In lithium-ion batteries, the world’s leading use of cobalt, the cobalt content is being reduced. In China, cobalt-free lithium iron phosphate batteries hold a significant market share.

Possible substitutes in other applications include barium or strontium ferrites, neodymium-iron-boron alloys, or nickel-iron alloys in magnets. Cerium, iron, lead, manganese, or vanadium are used as cobalt replacements in pigments.

Iron, iron-cobalt-nickel alloys, nickel, ceramic-metal composites (cermets), or ceramics are applied in cutting and wear-resistant materials.

Nickel-based alloys or ceramics replace cobalt in jet engines. In petroleum catalysts, nickel can substitute for cobalt, and titanium-based alloys are an alternative in prosthetics.