germanium element. Properties, extraction and application of germanium

Germanium- an element of the periodic table, extremely valuable for a person. Its unique properties as a semiconductor made it possible to create diodes widely used in various measuring instruments and radio receivers. It is needed for the production of lenses and optical fiber.

However, technical advances are only part of the advantages of this element. Organic germanium compounds have rare therapeutic properties, having a wide biological impact on human health and well-being, and this feature is more expensive than any precious metals.

The history of the discovery of germanium

Dmitry Ivanovich Mendeleev, analyzing his periodic table of elements, in 1871 suggested that it lacks one more element belonging to group IV. He described its properties, emphasized its similarity to silicon, and named it ekasilicon.

A few years later, in February 1886, a professor at the Freiberg Mining Academy discovered argyrodite, a new silver compound. His complete analysis Clemens Winkler, professor of technical chemistry and the best analyst of the academy, was entrusted with doing it. After studying a new mineral, he isolated 7% of its weight from it as a separate unidentified substance. A careful study of its properties showed that they were ecasilicon, predicted by Mendeleev. It is important that Winkler's method for separating ekasilicon is still used in its industrial production.

History of the name Germany

Ekasilicon in Mendeleev's periodic table occupies position 32. At first, Clemens Winkler wanted to give him the name Neptune, in honor of the planet, which was also first predicted and discovered later. However, it turned out that one falsely discovered component was already called that, and unnecessary confusion and disputes could arise.

As a result, Winkler chose the name Germanium for him, after his country, in order to remove all differences. Dmitry Ivanovich supported this decision, securing such a name for his "brainchild".

What does germanium look like?

This expensive and rare element is fragile like glass. A standard germanium ingot looks like a cylinder with a diameter of 10 to 35 mm. The color of germanium depends on its surface treatment and can be black, steel-like, or silver. Its appearance is easily confused with silicon, its closest relative and competitor.

To see small germanium details in devices, special magnification tools are needed.

The use of organic germanium in medicine

The organic germanium compound was synthesized by a Japanese doctor K. Asai in 1967. He proved that he had antitumor properties. Continued research has proven that various germanium compounds have such important properties for humans as pain relief, lowering blood pressure, reducing the risk of anemia, strengthening immunity and destroying harmful bacteria.

Directions of influence of germanium in the body:

• Promotes saturation of tissues with oxygen and,
• Accelerates wound healing
• Helps cleanse cells and tissues from toxins and poisons,
• Improves the condition of the central nervous system and its functioning
• Accelerates recovery after severe physical activity,
• Increases the overall performance of a person,
• Strengthens the protective reactions of the entire immune system.

The role of organic germanium in the immune system and in oxygen transport

The ability of germanium to carry oxygen at the level of body tissues is especially valuable for preventing hypoxia ( oxygen deficiency). It also reduces the likelihood of developing blood hypoxia, which occurs when the amount of hemoglobin in red blood cells decreases. Delivery of oxygen to any cell reduces the risk of oxygen starvation and saves from death the most sensitive to lack of oxygen cells: brain, kidney and liver tissues, heart muscles.

In 1870 D.I. Mendeleev, on the basis of the periodic law, predicted an as yet undiscovered element of group IV, calling it ekasilicium, and described its main properties. In 1886, the German chemist Clemens Winkler, during a chemical analysis of the mineral argyrodite, discovered this chemical element. Initially, Winkler wanted to name the new element "neptunium", but this name had already been given to one of the proposed elements, so the element was named after the scientist's homeland - Germany.

Being in nature, getting:

Germanium is found in sulfide ores, iron ore, is found in almost all silicates. The main minerals containing germanium: argyrodite Ag 8 GeS 6, confieldite Ag 8 (Sn,Ce)S 6, stottite FeGe(OH) 6, germanite Cu 3 (Ge,Fe,Ga)(S,As) 4, rhenierite Cu 3 ( Fe,Ge,Zn)(S,As) 4 .
As a result of complex and time-consuming operations for enrichment of ore and its concentration, germanium is isolated in the form of GeO 2 oxide, which is reduced with hydrogen at 600°C to a simple substance.
GeO 2 + 2H 2 \u003d Ge + 2H 2 O
Germanium is purified by zone melting, which makes it one of the most chemically pure materials.

Physical properties:

Gray-white solid with a metallic luster (mp 938°C, bp 2830°C)

Chemical properties:

Under normal conditions, germanium is resistant to air and water, alkalis and acids, it dissolves in aqua regia and in an alkaline solution of hydrogen peroxide. The oxidation states of germanium in its compounds: 2, 4.

The most important connections:

Germanium(II) oxide, GeO, grey-black, slightly sol. in-in, when heated, it disproportionates: 2GeO \u003d Ge + GeO 2
Germanium(II) hydroxide Ge(OH) 2 , red-orange. crystal,
germanium(II) iodide, GeI 2 , yellow cr., sol. in water, hydrol. bye.
Germanium(II) hydride, GeH 2 , tv. white por., easily oxidized. and decay.

Germanium(IV) oxide, GeO 2 , white crystals, amphoteric, obtained by hydrolysis of chloride, sulfide, germanium hydride, or by the reaction of germanium with nitric acid.
Germanium(IV) hydroxide, (germanic acid), H 2 GeO 3 , weak. unst. biaxial to-ta, germanate salts, for example. sodium germanate, Na 2 GeO 3 , white crystal, sol. in water; hygroscopic. There are also Na 2 hexahydroxogermanates (ortho-germanates), and polygermanates
Germanium(IV) sulfate, Ge(SO 4) 2 , colorless. cr., hydrolyzed by water to GeO 2, obtained by heating germanium (IV) chloride with sulfuric anhydride at 160 ° C: GeCl 4 + 4SO 3 \u003d Ge (SO 4) 2 + 2SO 2 + 2Cl 2
Germanium(IV) halides, fluoride GeF 4 - bests. gas, raw hydrol., reacts with HF, forming H 2 - germanofluoric acid: GeF 4 + 2HF \u003d H 2,
chloride GeCl 4 , colorless. liquid, hydr., bromide GeBr 4 , ser. cr. or colorless. liquid, sol. in org. conn.,
iodide GeI 4, yellow-orange. cr., slow. hydr., sol. in org. conn.
Germanium(IV) sulfide, GeS 2 , white kr., poorly sol. in water, hydrol., reacts with alkalis:
3GeS 2 + 6NaOH = Na 2 GeO 3 + 2Na 2 GeS 3 + 3H 2 O, forming germanates and thiogermanates.
Germanium(IV) hydride, "german", GeH 4 , colorless gas, organic derivatives of tetramethylgermane Ge(CH 3) 4 , tetraethylgermane Ge(C 2 H 5) 4 - colorless. liquids.

Application:

The most important semiconductor material, the main areas of application: optics, radio electronics, nuclear physics.

Germanium compounds are slightly toxic. Germanium is a microelement that in the human body increases the efficiency of the body's immune system, fights cancer, and reduces pain. It is also noted that germanium promotes the transfer of oxygen to the tissues of the body and is a powerful antioxidant - a blocker of free radicals in the body.
The daily requirement of the human body is 0.4–1.5 mg.
Germanium content champion among food products is garlic (750 mcg of germanium per 1 g dry weight of garlic cloves).

The material was prepared by students of the Institute of Physics and Chemistry of Tyumen State University
Demchenko Yu.V., Bornovolokova A.A.
Sources:
Germanium//Wikipedia./ URL: http://ru.wikipedia.org/?oldid=63504262 (date of access: 06/13/2014).
Germanium//Allmetals.ru/URL: http://www.allmetals.ru/metals/germanium/ (date of access: 06/13/2014).

Mini - abstract

"Element Germanium"

Target:

Describe the element Ge

Give a description of the properties of the element Ge

Tell about the application and use of this element

Element history ……….………………………………….……. one

Element properties …..……………………………………..…… 2

Application ……………….….…………………………………….. 3

Health hazard ………..………………………....… 4

Sources ………………………….…………………….…………… 5

From the history of the element..

Ggermanium(lat. Germanium) - a chemical element of group IV, the main subgroup periodic system DI. Mendeleev, denoted by the symbol Ge, belongs to the family of metals, serial number 32, atomic mass 72.59. It is a gray-white solid with a metallic luster.

The existence and properties of Germany were predicted in 1871 by Mendeleev and named this still unknown element - "Ekasilicon" because of the similarity of its properties with silicon.

In 1886, the German chemist K. Winkler, while examining the mineral, found that some unknown element was present in it, which was not detected by analysis. After hard work, he discovered the salts of a new element and isolated a certain amount of the element itself in its pure form. In the first report of the discovery, Winkler suggested that the new element was analogous to antimony and arsenic. Winkler intended to name the element Neptunium, but that name had already been given to one falsely discovered element. Winkler renamed the element he discovered to germanium (Germanium) in honor of his fatherland. And even Mendeleev, in a letter to Winkler, strongly supported the name of the element.

But until the second half of the 20th century, the practical use of Germany remained very limited. The industrial production of this element arose in connection with the development of semiconductor electronics.

Element PropertiesGe

For medical needs, germanium was the first to be used most widely in Japan. Tests of various organogermanium compounds in animal experiments and in human clinical trials have shown that they positively affect the human body to varying degrees. The breakthrough came in 1967 when Dr. K. Asai discovered that organic germanium has a wide range of biological effects.

Properties:

Carries oxygen in the tissues of the body - germanium in the blood behaves similarly to hemoglobin. It is involved in the process of oxygen transfer to the tissues of the body, which guarantees the normal functioning of all body systems.

stimulates the immune system - germanium in the form of organic compounds promotes the production of gamma-interferons, which inhibit the reproduction of rapidly dividing microbial cells, and activates specific immune cells (T-cells)

antitumor - germanium delays development malignant neoplasms and prevents the appearance of metastases, and also has protective properties against radioactive exposure.

biocidal (antifungal, antiviral, antibacterial) - germanium organic compounds stimulate the production of interferon - protective protein produced by the body in response to the introduction of foreign bodies.

Application and Use of the Element Germanium in Life

In industrial practice, germanium is obtained mainly from by-products of the processing of non-ferrous metal ores. Germanium concentrate (2-10% Germany) is obtained in various ways, depending on the composition of the raw material. To isolate very pure germanium, which is used in semiconductor devices, metal is melted by zone. Single-crystal germanium, necessary for the semiconductor industry, is usually obtained by zone melting.

This is one of the most valuable materials in modern semiconductor technology. It is used to make diodes, triodes, crystal detectors, and power rectifiers. Germanium is also used in dosimetric devices and devices that measure the intensity of constant and variable magnetic fields. An important field of application of the element is infrared technology, in particular the production of detectors. infrared radiation. Many alloys containing germanium are promising for practical use. For example, glasses based on GeO 2 and other Ge compounds. At room temperature, germanium is resistant to air, water, alkali solutions, and dilute hydrochloric and sulfuric acids, but readily dissolves in aqua regia and in an alkaline solution of hydrogen peroxide. And nitric acid oxidizes slowly.

Germanium alloys, which have high hardness and strength, are used in jewelry and denture technology for precision castings. Germanium is present in nature only in bound state and never free. The most common germanium-bearing minerals are argyrodite and germanite. Large reserves of germanium minerals are rare, but the element itself is widely found in other minerals, especially in sulfides (most often in zinc sulfides and silicates). Small amounts are also found in different types of hard coal.

World production Germany is 65 kg per year.

health hazard

Occupational health problems can be caused by dust dispersion during loading of germanium concentrate, grinding and loading of dioxide to isolate germanium metal, and loading of powdered germanium for remelting into bars. Other sources of harm to health are thermal radiation from tube furnaces and from the process of melting powdered germanium into bars, as well as the formation of carbon monoxide.

Absorbed germanium is rapidly excreted from the body, mainly in the urine. There is little information on the toxicity of inorganic germanium compounds to humans. Germanium tetrachloride is a skin irritant. In clinical trials and other long-term cases of oral administration of cumulative doses up to 16 g of spirogermanium, an organic germanium antitumor drug, or other germanium compounds, neurotoxic and nephrotoxic activity has been noted. Such doses are usually not subjected to production conditions. Animal experiments to determine the effect of germanium and its compounds on the body have shown that the dust of metallic germanium and germanium dioxide, when inhaled in high concentrations, leads to a general deterioration in health (limitation of weight gain). In the lungs of animals, morphological changes similar to proliferative reactions were found, such as thickening of the alveolar sections and hyperplasia of the lymphatic vessels around the bronchi and blood vessels. Germanium dioxide does not irritate the skin, but upon contact with the moist mucous membrane of the eye, it forms germanic acid, which acts as an ocular irritant. Long-term intraperitoneal injections at doses of 10 mg/kg lead to changes in peripheral blood .

The most harmful germanium compounds are germanium hydride and germanium chloride. Hydride can cause acute poisoning. Morphological examination of the organs of animals that died during the acute phase revealed disorders in the circulatory system and degenerative cellular changes in the parenchymal organs. Thus, hydride is a multipurpose poison that affects the nervous system and the peripheral circulatory system.

Germanium tetrachloride is a strong respiratory, skin, and eye irritant. Threshold concentration - 13 mg / m 3. At this concentration, it suppresses the pulmonary response at the cellular level in experimental animals. In high concentrations, it leads to irritation of the upper respiratory tract and conjunctivitis, as well as changes in the frequency and rhythm of breathing. Animals that survived acute poisoning developed catarrhal desquamative bronchitis and interstitial pneumonia a few days later. Germanium chloride also has a general toxic effect. Morphological changes were observed in the liver, kidneys and other organs of animals.

Sources of all information provided

Germanium |32 | Ge| — Price

Germanium (Ge) - trace rare metal, atomic number - 32, atomic mass-72.6, density:
solid at 25°C - 5.323 g/cm3;
liquid at 100°C - 5.557g/cm3;
Melting point - 958.5 ° C, coefficient of linear expansion α.106, at temperature, KO:
273-573— 6.1
573-923— 6.6
Hardness on a mineralogical scale-6-6.5.
Electrical resistivity of single-crystal high-purity germanium (at 298 OK), Ohm.m-0.55-0.6 ..
Germanium was discovered in 1885 and was initially obtained as a sulfide. This metal was predicted by D.I. Mendeleev in 1871, with an exact indication of its properties, and he called it ecosilicium. Germanium is named by scientific researchers after the country in which it was discovered.
Germanium is a silvery white metal, on appearance similar to tin, brittle under normal conditions. Amenable to plastic deformation at temperatures above 550°C. Germanium has semiconductor properties. The electrical resistivity of germanium depends on the purity—impurities sharply reduce it. Germanium is optically transparent in the infrared region of the spectrum, has a high refractive index, which allows it to be used for the manufacture of various optical systems.
Germanium is stable in air at temperatures up to 700°C, at higher temperatures it oxidizes, and above the melting point it burns to form germanium dioxide. Hydrogen does not interact with germanium, and at the melting point, the germanium melt absorbs oxygen. Germanium does not react with nitrogen. With chlorine, forms at room temperature, germanium chloride.
Germanium does not interact with carbon, is stable in water, slowly interacts with acids, and easily dissolves in aqua regia. Alkali solutions have little effect on germanium. Germanium alloys with all metals.
Despite the fact that germanium in nature is larger than lead, its production is limited due to its strong dispersal in the earth's crust, and the cost of germanium is quite high. Germanium forms the minerals argyrodite and germanite, but they are little used to obtain it. Germanium is extracted incidentally during the processing of polymetallic sulfide ores, some iron ores, which contain up to 0.001% germanium, from tar water during coal coking.

RECEIVING.

Obtaining germanium from various raw materials is carried out by complex methods, in which the final product is germanium tetrachloride or germanium dioxide, from which metallic germanium is obtained. It is purified and, further, germanium single crystals with desired electrophysical properties are grown by the method of zone melting. In industry, single-crystal and polycrystalline germanium are obtained.
Semi-products obtained by processing minerals contain a small amount of germanium and various methods of pyro- and hydrometallurgical processing are used for their enrichment. Pyrometallurgical methods are based on the sublimation of volatile compounds containing germanium, hydrometallurgical methods are based on the selective dissolution of germanium compounds.
To obtain germanium concentrates, products of pyrometallurgical enrichment (sublimes, cinders) are treated with acids and germanium is transferred into a solution from which a concentrate is obtained. various methods(precipitation, co-precipitation and sorption, electrochemical methods). The concentrate contains from 2 to 20% germanium, from which pure germanium dioxide is isolated. Germanium dioxide is reduced with hydrogen, however, the resulting metal is not pure enough for semiconductor devices and therefore it is purified by crystallographic methods (directed crystallization-zone purification-obtaining a single crystal). Directional crystallization is combined with the reduction of germanium dioxide with hydrogen. The molten metal is gradually pushed out of the hot zone into the refrigerator. The metal crystallizes gradually along the length of the ingot. Impurities are collected in the final part of the ingot and removed. The remaining ingot is cut into pieces, which are loaded into zone cleaning.
As a result of zone cleaning, an ingot is obtained, in which the purity of the metal is different along its length. The ingot is also cut and its individual parts are removed from the process. Thus, when obtaining single-crystal germanium from zone-cleaned, the direct yield is no more than 25%.
To obtain semiconductor devices, a single crystal of germanium is cut into plates, from which miniature parts are cut out, which are then ground and polished. These parts are the final product for the creation of semiconductor devices.

APPLICATION.

• Due to its semiconductor properties, germanium is widely used in radio electronics for the manufacture of crystalline rectifiers (diodes) and crystalline amplifiers (triodes), for computer technology, remote control, radar, etc.

• Germanium triodes are used to amplify, generate and convert electrical oscillations.

• In radio engineering, germanium film resistances are used.

• Germanium is used in photodiodes and photoresistors, for the manufacture of thermistors.

• In nuclear technology, germanium gamma-ray detectors are used, and in infrared technology devices, germanium lenses doped with gold are used.

• Germanium is added to alloys for highly sensitive thermocouples.

• Germanium is used as a catalyst in the production of artificial fibers.

• In medicine, some germanium organic compounds are being studied, suggesting that they can be biologically active and help delay the development of malignant tumors, lower blood pressure, and relieve pain.

Germanium (from the Latin Germanium), designated "Ge", an element of the IVth group of the periodic table of chemical elements of Dmitry Ivanovich Mendeleev; element number 32, atomic mass is 72.59. Germanium is a gray-white solid with a metallic luster. Although the color of germanium is a rather relative concept, it all depends on the surface treatment of the material. Sometimes it can be gray as steel, sometimes silvery, and sometimes completely black. Outwardly, germanium is quite close to silicon. These elements are not only similar to each other, but also have largely the same semiconductor properties. Their essential difference is the fact that germanium is more than twice as heavy as silicon.

Germanium, found in nature, is a mixture of five stable isotopes with mass numbers 76, 74, 73, 32, 70. Back in 1871, the famous chemist, "father" periodic table, Dmitri Ivanovich Mendeleev predicted the properties and existence of germanium. He called the element unknown at that time "ekasilicium", because. the properties of the new substance were in many respects similar to those of silicon. In 1886, after studying the mineral argyrdite, the German forty-eight-year-old chemist K. Winkler discovered a completely new chemical element in the natural mixture.

At first, the chemist wanted to call the element neptunium, because the planet Neptune was also predicted much earlier than it was discovered, but then he found out that such a name had already been used in the false discovery of one of the elements, so Winkler decided to abandon given title. The scientist was offered to name the element angularium, which means “controversial, angular”, but Winkler did not agree with this name either, although element No. 32 really caused a lot of controversy. The scientist was German by nationality, so he eventually decided to name the element germanium, in honor of his native country of Germany.

As it turned out later, germanium turned out to be nothing more than the previously discovered “ekasilicium”. Up until the second half of the twentieth century, the practical usefulness of germanium was rather narrow and limited. The industrial production of metal began only as a result of the beginning of the industrial production of semiconductor electronics.

Germanium is a semiconductor material widely used in electronics and engineering, as well as in the production of microcircuits and transistors. Radar installations use thin films of germanium, which are applied to glass and used as resistance. Alloys with germanium and metals are used in detectors and sensors.

The element does not have such strength as tungsten or titanium, it does not serve as an inexhaustible source of energy like plutonium or uranium, the electrical conductivity of the material is also far from the highest, and iron is the main metal in industrial technology. Despite this, germanium is one of the most important components of the technical progress of our society, because. it even earlier than silicon began to be used as a semiconductor material.

In this regard, it would be appropriate to ask: What is semiconductivity and semiconductors? Even experts cannot answer this question exactly, because. we can talk about the specifically considered property of semiconductors. There is also an exact definition, but only from the field of folklore: A semiconductor is a conductor for two cars.

A bar of germanium costs almost the same as a bar of gold. The metal is very fragile, almost like glass, so if you drop such an ingot, there is a high probability that the metal will simply break.

Germanium metal, properties

Biological properties

For medical needs, germanium was most widely used in Japan. The results of tests of organogermanium compounds on animals and humans have shown that they are able to have a beneficial effect on the body. In 1967, the Japanese doctor K. Asai discovered that organic germanium has a wide biological effect.

Among all its biological properties, it should be noted:

• - ensuring the transfer of oxygen to the tissues of the body;
• - increasing the immune status of the body;
• - manifestation of antitumor activity.

Subsequently, Japanese scientists created the world's first medical preparation with the content of germanium - "Germanium - 132".

In Russia, the first domestic drug containing organic germanium appeared only in 2000.

The processes of biochemical evolution of the surface of the earth's crust did not affect in the best way on the content of germanium in it. Most of the element has been washed from the land into the oceans, so that its content in the soil remains quite low.

Among plants that have the ability to absorb germanium from the soil, the leader is ginseng (germanium up to 0.2%). Germanium is also found in garlic, camphor and aloe, which are traditionally used in the treatment of various human diseases. In vegetation, germanium is found in the form of carboxyethyl semioxide. Now it is possible to synthesize sesquioxanes with a pyrimidine fragment - organic compounds of germanium. This connection its structure is close to natural, as in the root of ginseng.

Germanium can be attributed to rare trace elements. He is present in in large numbers various products, but in scanty doses. The daily intake of organic germanium is set at 8-10 mg. An assessment of 125 foodstuffs showed that about 1.5 mg of germanium enters the body daily with food. The content of the trace element in 1 g of raw foods is about 0.1 - 1.0 μg. Germanium is found in milk, tomato juice, salmon, and beans. But in order to satisfy daily requirement in Germany, you should drink 10 liters of tomato juice daily or eat about 5 kilograms of salmon. From the point of view of the cost of these products, the physiological properties of a person, and common sense Also, the use of such a quantity of germanium-containing products is not possible. On the territory of Russia, about 80-90% of the population has a lack of germanium, which is why special preparations have been developed.

Practical studies have shown that in the body germanium is most of all in the current intestine, stomach, spleen, bone marrow and blood. The high content of the microelement in the intestines and stomach indicates a prolonged action of the process of absorption of the drug into the blood. There is an assumption that organic germanium behaves in the blood in much the same way as hemoglobin, i.e. has a negative charge and is involved in the transfer of oxygen to the tissues. Thus, it prevents the development of hypoxia at the tissue level.

As a result of repeated experiments, the property of germanium to activate T-killers and promote the induction of gamma interferons, which suppress the process of reproduction of rapidly dividing cells, was proved. The main direction of action of interferons is antitumor and antiviral protection, radioprotective and immunomodulatory functions of the lymphatic system.

Germanium in the form of sesquioxide has the ability to act on hydrogen ions H +, smoothing out their detrimental effect on body cells. The guarantee of excellent operation of all systems of the human body is the uninterrupted supply of oxygen to the blood and all tissues. Organic germanium not only delivers oxygen to all points of the body, but also promotes its interaction with hydrogen ions.

• - Germanium is a metal, but its brittleness can be compared to glass.
• - Some reference books state that germanium has a silvery color. But this cannot be said, because the color of germanium directly depends on the method of processing the surface of the metal. Sometimes it can appear almost black, other times it has a steely color, and sometimes it can be silvery.
• - Germanium was found on the surface of the sun, as well as in the composition of meteorites that fell from space.
• - For the first time, an organoelement compound of germanium was obtained by the discoverer of the element Clemens Winkler from germanium tetrachloride in 1887, it was tetraethylgermanium. Of all received present stage none of the organoelement compounds of germanium is poisonous. In the same time most of tin and lead organic microelements, which are analogues of germanium in their physical qualities, are toxic.
• - Dmitri Ivanovich Mendeleev predicted three chemical elements even before their discovery, including germanium, calling the element ekasilicium due to its similarity to silicon. The prediction of the famous Russian scientist was so accurate that it simply amazed scientists, incl. and Winkler, who discovered germanium. The atomic weight according to Mendeleev was 72, in reality it was 72.6; the specific gravity according to Mendeleev was 5.5 in reality - 5.469; atomic volume according to Mendeleev was 13 in reality - 13.57; the highest oxide according to Mendeleev is EsO2, in reality - GeO2, its specific gravity according to Mendeleev was 4.7, in reality - 4.703; chloride compound according to Mendeleev EsCl4 - liquid, boiling point about 90 ° C, in fact - chloride compound GeCl4 - liquid, boiling point 83 ° C, compound with hydrogen according to Mendeleev EsH4 is gaseous, compound with hydrogen is actually GeH4 gaseous; organometallic compound according to Mendeleev Es(C2H5)4, boiling point 160 °C, organometallic compound in reality - Ge(C2H5)4 boiling point 163.5°C. As can be seen from the information reviewed above, Mendeleev's prediction was surprisingly accurate.
• - On February 26, 1886, Clemens Winkler began his letter to Mendeleev with the words "Dear Sir." He, in a rather polite manner, told the Russian scientist about the discovery of a new element, called germanium, which, in its properties, was nothing other than the previously predicted Mendeleev's "ekasilicium." Dmitri Ivanovich Mendeleev's answer was no less polite. The scientist agreed with the discovery of his colleague, calling germanium "the crown of his periodic system", and Winkler the "father" of the element worthy of wearing this "crown".
• - Germanium as a classical semiconductor has become the key to solving the problem of creating superconducting materials that operate at the temperature of liquid hydrogen, but not liquid helium. As you know, hydrogen passes into a liquid state from a gaseous state when the temperature reaches –252.6°C, or 20.5°K. In the 1970s, a film of germanium and niobium was developed, the thickness of which was only a few thousand atoms. This film is capable of maintaining superconductivity even at temperatures of 23.2°K and below.
• - When growing a germanium single crystal, a germanium crystal is placed on the surface of molten germanium - a “seed”, which is gradually raised by an automatic device, while the melt temperature slightly exceeds the melting point of germanium (937 ° C). The "seed" rotates so that the single crystal, as they say, "overgrown with meat" from all sides evenly. It should be noted that during such growth, the same thing happens as in the process of zone melting, i.e. practically only germanium passes into the solid phase, and all impurities remain in the melt.

Story

The existence of such an element as germanium was predicted back in 1871 by Dmitry Ivanovich Mendeleev, due to its similarities with silicon, the element was called ekasilicium. In 1886, a professor at the Freiberg Mining Academy discovered argyrodite, a new silver mineral. Then this mineral Klemens Winkler, professor of technical chemistry, studied quite carefully, conducting a complete analysis of the mineral. Forty-eight-year-old Winkler was rightfully considered the best analyst at the Freiberg Mining Academy, which is why he was given the opportunity to study argyrodite.

For quite short time the professor was able to provide a percentage report various elements in the original mineral: silver in its composition was 74.72%; sulfur - 17.13%; ferrous oxide - 0.66%; mercury - 0.31%; zinc oxide - 0.22%. But almost seven percent - it was the share of some incomprehensible element, which, it seems, had not yet been discovered at that distant time. In connection with this, Winkler decided to isolate the unidentified component of argyrodptus, to study its properties, and in the process of research he realized that he had actually found a completely new element - it was an explication predicted by D.I. Mendeleev.

However, it would be wrong to think that Winkler's work went smoothly. Dmitry Ivanovich Mendeleev, in addition to the eighth chapter of his book Fundamentals of Chemistry, writes: “At first (February 1886), the lack of material, as well as the absence of a spectrum in the flame and the solubility of germanium compounds, seriously hampered Winkler’s research ...” It is worth paying attention to the words “ no spectrum. But how so? In 1886 there was already a widely used method of spectral analysis. Using this method, elements such as thallium, rubidium, indium, cesium on Earth and helium on the Sun were discovered. Scientists already knew for certain that each chemical element without exception has an individual spectrum, and then suddenly there is no spectrum!

The explanation for this phenomenon appeared a little later. Germanium has characteristic spectral lines. Their wavelength is 2651.18; 3039.06 Ǻ and a few more. However, they all lie within the ultraviolet invisible part of the spectrum, it can be considered lucky that Winkler is an adherent traditional methods analysis, because it was these methods that led him to success.

Winkler's method for obtaining germanium from a mineral is quite close to one of modern industrial methods selection of the 32nd element. First, germanium, which was contained in argaroid, was converted into dioxide. Then the resulting white powder was heated to a temperature of 600-700 °C in a hydrogen atmosphere. In this case, the reaction turned out to be obvious: GeO 2 + 2H 2 → Ge + 2H 2 O.

It was by this method that the relatively pure element No. 32, germanium, was first obtained. At first, Winkler intended to name vanadium neptunium, after the planet of the same name, because Neptune, like germanium, was first predicted, and only then found. But then it turned out that such a name had already been used once, one chemical element, discovered falsely, was called neptunium. Winkler chose not to compromise his name and discovery, and abandoned neptunium. One French scientist Rayon suggested, however, later he recognized his proposal as a joke, he suggested calling the element angular, i.e. "controversial, angular", but Winkler did not like this name either. As a result, the scientist independently chose a name for his element, and named it germanium, in honor of his native country of Germany, over time, this name was established.

Until the 2nd floor. 20th century practical use of germanium remained rather limited. The industrial production of metal arose only in connection with the development of semiconductors and semiconductor electronics.

Being in nature

Germanium can be classified as a trace element. In nature, the element does not occur in its free form at all. The total metal content in the earth's crust of our planet by mass is 7 × 10 −4% %. This is more than the content of such chemical elements as silver, antimony or bismuth. But germanium's own minerals are quite scarce and very rare in nature. Almost all of these minerals are sulfosalts, for example, germanite Cu 2 (Cu, Fe, Ge, Zn) 2 (S, As) 4, confieldite Ag 8 (Sn,Ce)S 6, argyrodite Ag8GeS6 and others.

The main part of germanium dispersed in the earth's crust is contained in a huge number of rocks, as well as many minerals: sulfite ores of non-ferrous metals, iron ores, some oxide minerals (chromite, magnetite, rutile and others), granites, diabases and basalts. In the composition of some sphalerites, the content of the element can reach several kilograms per ton, for example, in frankeite and sulvanite 1 kg / t, in enargites the content of germanium is 5 kg / t, in pyrargyrite - up to 10 kg / t, but in other silicates and sulfides - tens and hundreds g/t. A small proportion of germanium is present in almost all silicates, as well as in some of the oil and coal deposits.

The main mineral of the element is germanium sulfite (formula GeS2). The mineral is found as an impurity in zinc sulfites and other metals. The most important germanium minerals are: germanite Cu 3 (Ge, Fe, Ga) (S, As) 4, plumbogermanite (Pb, Ge, Ga) 2 SO 4 (OH) 2 2H 2 O, stottite FeGe (OH) 6, rhenierite Cu 3 (Fe, Ge, Zn) (S, As) 4 and argyrodite Ag 8 GeS 6 .

Germanium is present in the territories of all states without exception. But none of the industrialized countries of the world has industrial deposits of this metal. Germanium is very, very dispersed. On Earth, minerals of this metal are considered to be very rare, the content of germanium in which is at least 1%. Such minerals include germanite, argyrodite, ultramafic, etc., including minerals discovered in recent decades: shtotite, renerite, plumbogermanite and confieldite. The deposits of all these minerals are not able to meet the demand modern industry in this rare and important chemical element.

The bulk of germanium is dispersed in minerals of other chemical elements, and is also found in natural waters, in coals, in living organisms and in soil. For example, the content of germanium in ordinary coal sometimes reaches more than 0.1%. But such a figure is quite rare, usually the share of germanium is lower. But there is almost no germanium in anthracite.

Receipt

During the processing of germanium sulfide, oxide GeO 2 is obtained, with the help of hydrogen it is reduced to obtain free germanium.

AT industrial production germanium is mined mainly as a by-product from the processing of non-ferrous metal ores (zinc blende, zinc-copper-lead polymetallic concentrates containing 0.001-0.1% germanium), coal ash, and some coke products.

Initially, germanium concentrate (from 2% to 10% germanium) is isolated from the sources discussed above in various ways, the choice of which depends on the composition of the raw material. In the processing of boxing coals, germanium is partially precipitated (from 5% to 10%) into the tar water and resin, from there it is extracted in combination with tannin, after which it is dried and fired at a temperature of 400-500 ° C. The result is a concentrate that contains about 30-40% germanium, germanium is isolated from it in the form of GeCl 4 . The process of extracting germanium from such a concentrate, as a rule, includes the same stages:

1) The concentrate is chlorinated with hydrochloric acid, a mixture of acid and chlorine in aquatic environment or other chlorinating agents, which may result in technical GeCl 4 . In order to purify GeCl 4, rectification and extraction of impurities of concentrated hydrochloric acid are used.

2) Hydrolysis of GeCl 4 is carried out, the hydrolysis products are calcined until GeO 2 oxide is obtained.

3) GeO is reduced with hydrogen or ammonia to pure metal.

When obtaining the purest germanium, which is used in semiconductor technical means, carry out zone melting of metal. Single-crystal germanium, necessary for semiconductor production, is usually obtained by zone melting or by the Czochralski method.

Methods for isolating germanium from tar waters of coke plants were developed by the Soviet scientist V.A. Nazarenko. In this raw material, germanium is not more than 0.0003%, however, using an oak extract from them, it is easy to precipitate germanium in the form of a tannide complex.

The main component of tannin is an ester of glucose, where the meta-digallic acid radical is present, which binds germanium, even if the concentration of the element in solution is very low. From the sediment, you can easily get a concentrate, the content of germanium dioxide in which is up to 45%.

Subsequent transformations will already depend little on the type of raw material. Germanium is reduced with hydrogen (as in the case of Winkler in the 19th century), however, germanium oxide must first be isolated from numerous impurities. The successful combination of the qualities of one germanium compound proved to be very useful for solving this problem.

Germanium tetrachloride GeCl4. is a volatile liquid that boils at just 83.1°C. Therefore, it is quite conveniently purified by distillation and rectification (in quartz columns with packing).

GeCl4 is almost insoluble in hydrochloric acid. This means that the dissolution of HCl impurities can be used to purify it.

Purified germanium tetrachloride is treated with water, purified with ion-exchange resins. A sign of the desired purity is an increase in the resistivity of water to 15-20 million ohm cm.

Hydrolysis of GeCl4 occurs under the action of water:

GeCl4 + 2H2O → GeO2 + 4HCl.

It can be seen that we have before us the "written backwards" equation for the reaction of obtaining germanium tetrachloride.

Then comes the reduction of GeO2 using purified hydrogen:

GeO2 + 2 H2O → Ge + 2 H2O.

As a result, powdered germanium is obtained, which is alloyed and then purified by the zone melting method. This method purification was developed back in 1952 specifically for the purification of germanium.

The impurities necessary to give germanium a particular type of conductivity are introduced at the final stages of production, namely during zone melting, as well as during the growth of a single crystal.

Application

Germanium is a semiconductor material used in electronics and technology in the production of microcircuits and transistors. The thinnest films of germanium are applied to glass and used as resistance in radar installations. Germanium alloys with various metals used in the manufacture of detectors and sensors. Germanium dioxide is widely used in the production of glasses that have the property of transmitting infrared radiation.

Germanium telluride has been serving as a stable thermoelectric material for a very long time, and also as a component of thermoelectric alloys (thermo-mean emf with 50 µV/K). strategic role ultra-high purity germanium plays a role in the manufacture of prisms and lenses for infrared optics. The largest consumer of germanium is infrared optics, which is used in computer technology, sighting and missile guidance systems, night vision devices, mapping and exploration of the earth's surface from satellites. Germanium is also widely used in fiber optic systems (adding germanium tetrafluoride to glass fibers), as well as in semiconductor diodes.

Germanium as a classical semiconductor has become the key to solving the problem of creating superconducting materials that operate at the temperature of liquid hydrogen, but not liquid helium. As you know, hydrogen passes into a liquid state from a gaseous state when the temperature reaches -252.6°C, or 20.5°K. In the 1970s, a film of germanium and niobium was developed, the thickness of which was only a few thousand atoms. This film is capable of maintaining superconductivity even at temperatures of 23.2°K and below.

By fusing indium into the HES plate, thus creating a region with the so-called hole conductivity, a rectifying device is obtained, i.e. diode. The diode has the property to pass electric current in one direction: the electron region from the region with hole conduction. After indium is fused on both sides of the HES plate, this plate becomes the basis of the transistor. For the first time in the world, a germanium transistor was created back in 1948, and after only twenty years, hundreds of millions of such devices were produced.

Diodes based on germanium and triodes have become widely used in televisions and radios, in a wide variety of measuring equipment and calculating devices.

Germanium is also used in other especially important areas of modern technology: when measuring low temperatures, when detecting infrared radiation, etc.

The use of the broom in all these areas requires germanium of very high chemical and physical purity. Chemical purity is such a purity at which the amount of harmful impurities should not be more than one ten-millionth of a percent (10-7%). Physical purity means a minimum of dislocations, a minimum of disturbances in the crystal structure of a substance. To achieve it, single-crystal germanium is specially grown. In this case, the entire metal ingot is just one crystal.

To do this, a germanium crystal is placed on the surface of molten germanium - a "seed", which gradually rises using an automatic device, while the melt temperature slightly exceeds the melting point of germanium (937 ° C). The "seed" rotates so that the single crystal, as they say, "overgrown with meat" from all sides evenly. It should be noted that during such growth, the same thing happens as in the process of zone melting, i.e. practically only germanium passes into the solid phase, and all impurities remain in the melt.

Physical properties

Probably, few of the readers of this article had to visually see vanadium. The element itself is quite scarce and expensive, they do not make consumer goods from it, and their germanium filling, which happens in electrical appliances, is so small that it is not possible to see the metal.

Some reference books state that germanium is silver in color. But this cannot be said, because the color of germanium directly depends on the method of processing the surface of the metal. Sometimes it can appear almost black, other times it has a steely color, and sometimes it can be silvery.

Germanium is such a rare metal that the cost of its ingot can be compared with the cost of gold. Germanium is characterized by increased brittleness, which can only be compared with glass. Outwardly, germanium is quite close to silicon. These two elements are both competitors for the title of the most important semiconductor and analogues. Although some of the technical properties of the element are largely similar, as regards the appearance of the materials, it is very easy to distinguish germanium from silicon, germanium is more than twice as heavy. The density of silicon is 2.33 g/cm3 and the density of germanium is 5.33 g/cm3.

But it is impossible to speak unambiguously about the density of germanium, because. the figure 5.33 g/cm3 refers to germanium-1. This is one of the most important and most common modification of the five allotropic modifications of the 32nd element. Four of them are crystalline and one is amorphous. Germanium-1 is the lightest of the four crystalline modifications. Its crystals are built exactly the same as diamond crystals, a = 0.533 nm. However, if this structure is maximally dense for carbon, then germanium also has denser modifications. Moderate heat and high pressure (about 30 thousand atmospheres at 100 ° C) converts germanium-1 to germanium-2, structure crystal lattice which is exactly the same as that of white tin. We use the same method to obtain germanium-3 and germanium-4, which are even denser. All these "not quite ordinary" modifications are superior to germanium-1 not only in density, but also in electrical conductivity.

The density of liquid germanium is 5.557 g/cm3 (at 1000°C), the melting temperature of the metal is 937.5°C; the boiling point is about 2700°C; the value of the thermal conductivity coefficient is approximately 60 W / (m (K), or 0.14 cal / (cm (sec (deg)) at a temperature of 25 ° C. At ordinary temperatures, even pure germanium is fragile, but when it reaches 550 ° C, it begins to succumb On the mineralogical scale, the hardness of germanium is from 6 to 6.5, the value of the compressibility coefficient (in the pressure range from 0 to 120 H / m 2, or from 0 to 12000 kgf / mm 2) is 1.4 10-7 m 2 /mn (or 1.4 10-6 cm 2 /kgf), the surface tension is 0.6 n/m (or 600 dynes/cm).

Germanium is a typical semiconductor with a band gap size of 1.104·10 -19 or 0.69 eV (at 25°C); in high purity germanium, the electrical resistivity is 0.60 ohm (m (60 ohm (cm) (25 ° C); the electron mobility index is 3900, and the hole mobility is 1900 cm 2 / in. sec (at 25 ° C and at content from 8% of impurities.) For infrared rays, the wavelength of which is more than 2 microns, the metal is transparent.

Germanium is rather brittle, it cannot be hot or cold worked by pressure below 550 °C, but if the temperature rises, the metal becomes ductile. The hardness of the metal on the mineralogical scale is 6.0-6.5 (germanium is sawn into plates using a metal or diamond disk and an abrasive).

Chemical properties

Germanium, being in chemical compounds usually exhibits second and fourth valencies, but tetravalent germanium compounds are more stable. Germanium at room temperature is resistant to the action of water, air, as well as alkali solutions and dilute concentrates of sulfuric or hydrochloric acid, but the element dissolves quite easily in aqua regia or an alkaline solution of hydrogen peroxide. The element is slowly oxidized by the action of nitric acid. Upon reaching a temperature of 500-700 ° C in air, germanium begins to oxidize to GeO 2 and GeO oxides. (IV) germanium oxide is a white powder with a melting point of 1116°C and a solubility in water of 4.3 g/l (at 20°C). By their own chemical properties the substance is amphoteric, soluble in alkali, with difficulty in mineral acid. It is obtained by the penetration of the hydrated precipitate GeO 3 nH 2 O, which is released during hydrolysis Germanium acid derivatives, for example, metal germanates (Na 2 GeO 3 , Li 2 GeO 3 , etc.) are solid substances that have high temperatures melting, can be obtained by fusing GeO 2 and other oxides.

As a result of the interaction of germanium and halogens, the corresponding tetrahalides can be formed. The reaction is easiest to proceed with chlorine and fluorine (even at room temperature), then with iodine (temperature 700-800 ° C, presence of CO) and bromine (with low heating). One of the most important germanium compounds is tetrachloride (formula GeCl 4). It is a colorless liquid with a melting point of 49.5°C, a boiling point of 83.1°C and a density of 1.84 g/cm3 (at 20°C). The substance is strongly hydrolyzed by water, releasing a precipitate of hydrated oxide (IV). The tetrachloride is obtained by chlorination of metallic germanium or by the interaction of GeO 2 oxide and concentrated hydrochloric acid. Germanium dihalides with the general formula GeX 2 , hexachlorodigermane Ge 2 Cl 6 , GeCl monochloride, as well as germanium oxychlorides (for example, CeOCl 2) are also known.

Upon reaching 900-1000 ° C, sulfur interacts vigorously with germanium, forming GeS 2 disulfide. It is a white solid with a melting point of 825°C. The formation of GeS monosulfide and similar compounds of germanium with tellurium and selenium, which are semiconductors, are also possible. At a temperature of 1000–1100 °C, hydrogen slightly reacts with germanium, forming germine (GeH) X, which is an unstable and highly volatile compound. Germanic hydrogens of the series Ge n H 2n + 2 to Ge 9 H 20 can be formed by reacting germanides with dilute HCl. Germylene is also known with the composition GeH 2 . Germanium does not react directly with nitrogen, but there is Ge 3 N 4 nitride, which is obtained by the action of ammonia on germanium (700-800 ° C). Germanium does not interact with carbon. With many metals, germanium forms various compounds - germanides.

Many complex compounds of germanium are known, which are becoming increasingly important in the analytical chemistry of the element germanium, as well as in the processes of obtaining chemical element. Germanium is able to form complex compounds with hydroxyl-containing organic molecules (polyhydric alcohols, polybasic acids, and others). There are also germanium heteropoly acids. Like other Group IV elements, germanium characteristically forms organometallic compounds. An example is tetraethylgermane (C 2 H 5) 4 Ge 3 .