Named after Germany. A scientist from this country discovered and had the right to call it whatever he wanted. So in got germanium.
However, it was not Mendeleev who was lucky, but Clemens Winkler. He was assigned to study argyrodite. A new mineral, consisting mainly of, was found at the Himmelfurst mine.
Winkler determined 93% of the stone's composition and hit a dead end with the remaining 7%. The conclusion was that they included an unknown element.
More careful analysis has borne fruit. germanium discovered. This is metal. How is it useful to mankind? About this, and not only, we will tell further.
germanium properties
Germanium - 32 element of the periodic table. It turns out that the metal is included in the 4th group. The number corresponds to the valency of the elements.
That is, germanium tends to form 4 chemical bonds. This makes the element discovered by Winkler look like .
Hence the desire of Mendeleev to name the still undiscovered element ecosilicium, denoted as Si. Dmitry Ivanovich calculated the properties of the 32nd metal in advance.
germanium looks like silicon chemical properties. Reacts with acids only when heated. With alkalis "communicates" in the presence of oxidizing agents.
Resistant to water vapor. Does not react with hydrogen, carbon,. Germanium lights up at a temperature of 700 degrees Celsius. The reaction is accompanied by the formation of germanium dioxide.
The 32nd element easily interacts with halogens. These are salt-forming substances from group 17 of the table.
In order not to get confused, we indicate that we focus on new standard. In the old, this is the 7th group of the periodic table.
Whatever the table, the metals in it are located to the left of the stepped diagonal line. The 32nd element is an exception.
Another exception is . She may also react. Antimony is deposited on the substrate.
Active interaction is ensured with. Like most metals, germanium is capable of burning in its vapors.
Externally germanium element, grayish-white, with a pronounced metallic sheen.
By revising internal structure, the metal has a cubic structure. It reflects the arrangement of atoms in elementary cells.
They are shaped like cubes. Eight atoms are located at the vertices. The structure is close to the lattice.
Element 32 has 5 stable isotopes. Their presence is a property of all elements of the germanium subgroup.
They are even, which determines the presence of stable isotopes. For example, there are 10 of them.
The density of germanium is 5.3-5.5 grams per cubic centimeter. The first indicator is typical for the state, the second - for the liquid metal.
In a softened form, it is not only more dense, but also plastic. Brittle at room temperature, the substance becomes at 550 degrees. These are features of germanium.
The hardness of the metal at room temperature is about 6 points.
In this state, the 32nd element is a typical semiconductor. But, the property becomes "brighter" as the temperature rises. Just conductors, for comparison, lose their properties when heated.
Germanium conducts current not only in standard form but also in solutions.
In terms of semiconductor properties, the 32nd element is also close to silicon and is just as common.
However, the areas of application of substances differ. Silicon is a semiconductor used in solar cells, including the thin-film type.
The element is also needed for photocells. Now, consider where germanium comes in handy.
Application of germanium
Germanium is used in gamma spectroscopy. Its instruments make it possible, for example, to study the composition of additives in mixed catalyst oxides.
In the past, germanium was added to diodes and transistors. In solar cells, the properties of a semiconductor also come in handy.
But, if silicon is added to standard models, then germanium is added to highly efficient, new generation ones.
The main thing is not to use germanium at a temperature close to absolute zero. Under such conditions, the metal loses its ability to transmit voltage.
In order for germanium to be a conductor, impurities in it should be no more than 10%. Perfect Ultra Clean chemical element.
Germanium made by this method of zone melting. It is based on the different solubility of foreign elements in liquid and phases.
formula germanium allows you to apply it in practice. Here we are no longer talking about the semiconductor properties of the element, but about its ability to harden.
For the same reason, germanium has found application in dental prosthetics. Although crowns are becoming obsolete, there is still a small demand for them.
If you add silicon and aluminum to germanium, solders are obtained.
Their melting point is always lower than that of the joined metals. So, you can make complex, design designs.
Even the Internet without germanium would be impossible. The 32nd element is present in the optical fiber. In its core is quartz with an admixture of hero.
And its dioxide increases the reflectivity of the fiber. Considering the demand for it, electronics, industrialists need germanium in large volumes. Which ones, and how they are provided, we will study below.
mining germanium
Germanium is quite common. In the earth's crust, the 32nd element, for example, is more than, antimony, or.
Explored reserves are about 1,000 tons. Almost half of them are hidden in the bowels of the United States. Another 410 tons are property.
So, the rest of the countries, basically, have to buy raw materials. cooperates with the Celestial Empire. This is justified both from a political point of view and from an economic point of view.
Properties of the element germanium, associated with its geochemical relationship with widespread substances, do not allow the metal to form its own minerals.
Usually, the metal is introduced into the lattice of existing ones. The guest, of course, will not take up much space.
Therefore, you have to extract germanium bit by bit. In you can find a few kilos per ton of rock.
Enargits contain no more than 5 kilos of germanium per 1000 kilograms. In pyrargyrite 2 times more.
A ton of element 32 sulvanite contains no more than 1 kilogram. Most often, germanium is extracted as a by-product from ores of other metals, for example, or non-ferrous, such as chromite, magnetite, rutite.
Annual production of germanium ranges from 100-120 tons, depending on demand.
Basically, the single-crystal form of the substance is purchased. This is exactly what is needed for the production of spectrometers, optical fiber, precious. Let's find out the rates.
germanium price
Monocrystalline germanium is mainly purchased by the ton. For large industries, this is beneficial.
1,000 kilograms of the 32nd element costs about 100,000 rubles. You can find offers for 75,000 - 85,000.
If we take polycrystalline, that is, with aggregates smaller and increased strength, you can give 2.5 times more per kilo of raw materials.
Standard length is not less than 28 centimeters. The blocks are protected with a film, as they fade in the air. Polycrystalline germanium - "soil" for growing single crystals.
Germanium- an element of the periodic table, extremely valuable for a person. His 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
Dmitri 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. Its full analysis was commissioned to be done by Clemens Winkler, professor of technical chemistry and the Academy's top analyst. 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 extraction method for exasilicon 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, you need special means magnification.
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 different connections germany 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 heavy 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.
(Germanium; from lat. Germania - Germany), Ge - chemical. element of group IV of the periodic system of elements; at. n. 32, at. m. 72.59. Silvery-gray substance with a metallic sheen. In chem. compounds exhibits oxidation states + 2 and +4. Compounds with an oxidation state of +4 are more stable. Natural germanium consists of four stable isotopes with mass numbers 70 (20.55%), 72 (27.37%), 73(7.67%) and 74 (36.74%) and one radioactive isotope with mass number 76 ( 7.67%) and a half-life of 2,106 years. Artificially (with the help of various nuclear reactions) many radioactive isotopes have been obtained; the most important is the 71 Ge isotope with a half-life of 11.4 days.
The existence of holy germanium (under the name "ekasilitsiy") was predicted in 1871 by the Russian scientist D. I. Mendeleev. However, only in 1886 it. the chemist K. Winkler discovered an unknown element in the mineral argyrodite, the properties of which coincided with the properties of “ecasilicon”. Beginning of prom. the production of germanium dates back to the 40s. 20th century, when it was used as a semiconductor material. The content of germanium in the earth's crust (1-2) is 10~4%. Germanium is a trace element and is rarely found as its own minerals. Seven minerals are known, in which its concentration is more than 1%, among them: Cu2 (Cu, Ge, Ga, Fe, Zn) 2 (S, As) 4X X (6.2-10.2% Ge), rhenierite (Cu, Fe)2 (Cu, Fe, Ge, Ga, Zn)2 X X (S, As)4 (5.46-7.80% Ge) and argyrodite Ag8GeS6 (3/55-6.93% Ge) . G. also accumulates in caustobioliths (humic coals, oil shale, oil). Resistant at normal conditions G.'s crystalline modification has a cubic structure like diamond, with a period a = 5.65753 A (Gel).
The density of germanium (t-ra 25 ° C) 5.3234 g / cm3, tmelt 937.2 ° C; tbp 2852°C; heat of fusion 104.7 cal/g, heat of sublimation 1251 cal/g, heat capacity (temperature 25°C) 0.077 cal/g deg; coefficient thermal conductivity, (t-ra 0 ° C) 0.145 cal / cm sec deg, temperature coefficient. linear expansion (t-ra 0-260 ° C), 5.8 x 10-6 deg-1. Upon melting, germanium decreases in volume (by approximately 5.6%), its density increases by 4% h. high pressure diamond-like modification. Germanium undergoes polymorphic transformations, forming crystalline modifications: a tetragonal structure of the B-Sn type (GeII), a body-centered tetragonal structure with periods a = 5.93 A, c = 6.98 A (GeIII) and a body-centered cubic structure with a period a = 6, 92A(GeIV). These modifications are characterized by higher density and electrical conductivity compared to GeI.
Amorphous germanium can be obtained in the form of films (about 10-3 cm thick) by steam condensation. Its density is less than the density of crystalline G. The structure of the energy zones in the G. crystal determines its semiconductor properties. The width of the band gap G. is equal to 0.785 eV (t-ra 0 K), specific electrical resistance(t-ra 20 ° C) 60 ohm cm and with an increase in t-ry it significantly decreases according to an exponential law. Impurities give G. t. impurity conductivity of the electronic (impurities of arsenic, antimony, phosphorus) or hole (impurities of gallium, aluminum, indium) type. The mobility of charge carriers in G. (t-ra 25 ° C) for electrons is about 3600 cm2 / v sec, for holes - 1700 cm2 / v sec, the intrinsic concentration of charge carriers (t-ra 20 ° C) is 2.5. 10 13 cm-3. G. is diamagnetic. Upon melting, it transforms into a metallic state. Germanium is very brittle, its Mohs hardness is 6.0, microhardness is 385 kgf/mm2, compressive strength (temperature 20°C) is 690 kgf/cm2. With an increase in t-ry, hardness decreases, above t-ry 650 ° C, it becomes plastic, amenable to fur. processing. Germanium is practically inert to air, oxygen and to non-oxidizing electrolytes (if there is no dissolved oxygen) at temperatures up to 100 ° C. Resistant to the action of hydrochloric and dilute sulfuric acid; slowly dissolves in concentrated sulfuric and nitric acids when heated (the resulting film of dioxide slows down dissolution), dissolves well in aqua regia, in solutions of hypochlorites or alkali hydroxides (in the presence of hydrogen peroxide), in alkali melts, peroxides, nitrates and carbonates of alkali metals.
Above t-ry 600 ° C is oxidized in air and in a stream of oxygen, forming oxide GeO and dioxide (Ge02) with oxygen. Germanium oxide is a dark gray powder sublimating at t-re 710 ° C, slightly soluble in water with the formation of a weak germanite to-you (H2Ge02), a salt swarm (germanites) of low resistance. GeO readily dissolves in acids with the formation of divalent G salts. Germanium dioxide is a powder white color, exists in several polymorphic modifications that differ greatly in chemical. St. you: the hexagonal modification of dioxide is relatively well soluble in water (4.53 zU at t-re 25 ° C), alkali solutions and to-t, the tetragonal modification is practically insoluble in water and inert to acids. Dissolving in alkalis, the dioxide and its hydrate form salts of metagermanate (H2Ge03) and orthogermanate (H4Ge04) to-t - germanates. Alkali metal germanates dissolve in water, the remaining germanates are practically insoluble; freshly precipitated dissolve in mineral to-tah. G. easily combines with halogens, forming when heated (about t-ry 250 ° C) the corresponding tetrahalogenides - non-salt-like compounds that are easily hydrolyzed by water. G. are known - dark brown (GeS) and white (GeS2).
Germanium is characterized by compounds with nitrogen - brown nitride (Ge3N4) and black nitride (Ge3N2), characterized by a smaller chemical. tenacity. With phosphorus G. forms a low-resistant phosphide (GeP) of black color. It does not interact with carbon and does not alloy; it forms a continuous series of solid solutions with silicon. Germanium, as an analog of carbon and silicon, is characterized by the ability to form germanohydrogens of the GenH2n + 2 type (germanes), as well as solid compounds of the GeH and GeH2 types (germenes). Germanium forms metal connections() and with many others. metals. G.'s extraction from raw materials consists in receiving a rich germanium concentrate, and from it - high purity. In the prom. on a scale, germanium is obtained from tetrachloride, using its high volatility during purification (for isolation from concentrate), low in concentrated hydrochloric acid and high in organic solvents (for purification from impurities). Often for enrichment use high volatility of the lower sulfide and oxide G., to-rye are easily sublimated.
To obtain semiconductor germanium, directional crystallization and zone recrystallization are used. Monocrystalline germanium is obtained by drawing from the melt. In the process of growing G., special alloys are added. additives, adjusting certain properties of the monocrystal. G. is supplied in the form of ingots with a length of 380-660 mm and a cross section of up to 6.5 cm2. Germanium is used in radio electronics and electrical engineering as a semiconductor material for the manufacture of diodes and transistors. Lenses for infrared optics devices, dosimeters for nuclear radiation, X-ray spectroscopy analyzers, sensors using the Hall effect, and converters of radioactive decay energy into electrical energy are made from it. Germanium is used in microwave attenuators, resistance thermometers, operated at a temperature of liquid helium. The G. film deposited on the reflector is distinguished by high reflectivity and good corrosion resistance. germanium with some metals, characterized by increased resistance to acidic aggressive environments, is used in instrument making, mechanical engineering and metallurgy. gemanium with gold form a low-melting eutectic and expand upon cooling. G.'s dioxide is used for the manufacture of special. glass, characterized by a high coefficient. refraction and transparency in the infrared part of the spectrum, glass electrodes and thermistors, as well as enamels and decorative glazes. Germanates are used as activators of phosphors and phosphors.
Germanium - a chemical element of the periodic system of chemical elements D.I. Mendeleev. And denoted by the symbol Ge, germanium is a simple substance that is gray-white in color and has solid characteristics like a metal.
The content in the earth's crust is 7.10-4% by weight. refers to trace elements, due to its reactivity to oxidation in the free state, it does not occur as a pure metal.
Finding germanium in nature
Germanium is one of the three chemical elements predicted by D.I. Mendeleev on the basis of their position in the periodic system (1871).
It belongs to rare trace elements.
At present, the main sources industrial production germanium is a waste of zinc production, coal coking, ash of some types of coal, in silicate impurities, sedimentary iron rocks, in nickel and tungsten ores, peat, oil, geothermal waters and in some algae.
The main minerals containing germanium
Plumbohermatite (PbGeGa) 2 SO 4 (OH) 2 + H 2 O content up to 8.18%
yargyrodite AgGeS6 contains from 3.65 to 6.93% germany.
rhenierite Cu 3 (FeGeZn)(SAs) 4 contains from 5.5 to 7.8% germanium.
In some countries, obtaining germanium is a by-product of the processing of certain ores such as zinc-lead-copper. Germanium is also obtained in the production of coke, as well as in brown coal ash with a content of 0.0005 to 0.3% and in hard coal ash with a content of 0.001 to 1 -2%.
Germanium as a metal is very resistant to the action of atmospheric oxygen, oxygen, water, some acids, dilute sulfuric and hydrochloric acids. But concentrated sulfuric acid reacts very slowly.
Germanium reacts with nitric acid HNO 3 and aqua regia, slowly reacts with caustic alkalis to form a germanate salt, but with the addition of hydrogen peroxide H 2O2 the reaction is very fast.
When exposed to high temperatures above 700 °C, germanium is easily oxidized in air to form GeO 2 , readily reacts with halogens to form tetrahalides.
Does not react with hydrogen, silicon, nitrogen and carbon.
Volatile germanium compounds are known with the following characteristics:
Germany hexahydride-digermane, Ge 2 H 6 - combustible gas, decomposes during long-term storage in the light, turning yellow then brown turning into a dark solid Brown color decomposed by water and alkalis.
Germany tetrahydride, monogermane - GeH 4 .
Application of germanium
Germanium, like some others, has the properties of so-called semiconductors. All according to their electrical conductivity are divided into three groups: conductors, semiconductors and insulators (dielectrics). The specific electrical conductivity of metals is in the range 10V4 - 10V6 Ohm.cmV-1, the division given is conditional. However, one can point out a fundamental difference in the electrophysical properties of conductors and semiconductors. For the former, the electrical conductivity decreases with increasing temperature, for semiconductors it increases. At temperatures close to absolute zero, semiconductors turn into insulators. As is known, metallic conductors exhibit the properties of superconductivity under such conditions.
Semiconductors can be various substances. These include: boron, ( or
Germanium is a chemical element with atomic number 32 in the periodic system, denoted by the symbol Ge (Ger. Germanium).
The history of the discovery of germanium
The existence of the element ekasilicium, an analogue of silicon, was predicted by D.I. Mendeleev back in 1871. And in 1886, one of the professors of the Freiberg Mining Academy discovered a new silver mineral - argyrodite. This mineral was then given to the professor of technical chemistry Clemens Winkler for a complete analysis.
This was not done by chance: 48-year-old Winkler was considered the best analyst of the academy.
Quite quickly, he found out that silver in the mineral is 74.72%, sulfur - 17.13, mercury - 0.31, ferrous oxide - 0.66, zinc oxide - 0.22%. And almost 7% of the weight of the new mineral was accounted for by some incomprehensible element, most likely still unknown. Winkler singled out the unidentified component of the argyrodite, studied its properties and realized that he had indeed found a new element - the explication predicted by Mendeleev. This is a brief history of the element with atomic number 32.
However, it would be wrong to think that Winkler's work went smoothly, without a hitch, without a hitch. Here is what Mendeleev writes about this in the supplements to the eighth chapter of Fundamentals of Chemistry: “At first (February 1886), the lack of material, the absence of a spectrum in the burner flame and the solubility of many germanium compounds made Winkler’s research difficult ...” Pay attention to the “lack of spectrum in the flame. How so? Indeed, in 1886 the method of spectral analysis already existed; Rubidium, cesium, thallium, indium have already been discovered on Earth by this method, and helium on the Sun. Scientists knew for sure that each chemical element has a completely individual spectrum, and suddenly there is no spectrum!
The explanation came later. Germanium has characteristic spectral lines - with a wavelength of 2651.18, 3039.06 Ǻ and a few more. But they all lie in the invisible ultraviolet part of the spectrum, and it can be considered fortunate that Winkler's adherence to traditional methods of analysis - they led to success.
Winkler's method for isolating germanium is similar to one of the current industrial methods for obtaining element No. 32. First, the germanium contained in the argarite was converted into dioxide, and then this white powder was heated to 600...700°C in a hydrogen atmosphere. The reaction is obvious: GeO 2 + 2H 2 → Ge + 2H 2 O.
Thus, relatively pure germanium was obtained for the first time. Winkler initially intended to name the new element neptunium, after the planet Neptune. (Like element #32, this planet was predicted before it was discovered.) But then it turned out that such a name had previously been assigned to one falsely discovered element, and, not wanting to compromise his discovery, Winkler abandoned his first intention. He did not accept the proposal to call the new element angular, i.e. “angular, controversial” (and this discovery really caused a lot of controversy). True, the French chemist Rayon, who put forward such an idea, later said that his proposal was nothing more than a joke. Winkler named the new element germanium after his country, and the name stuck.
Finding germanium in natureIt should be noted that in the process of geochemical evolution of the earth's crust, a significant amount of germanium was washed out from most of the land surface into the oceans, therefore, at present, the amount of this trace element contained in the soil is extremely insignificant.
The total content of germanium in the earth's crust is 7 × 10 −4% by mass, that is, more than, for example, antimony, silver, bismuth. Germanium, due to its insignificant content in the earth's crust and geochemical affinity with some widespread elements, exhibits a limited ability to form its own minerals, dispersing in the lattices of other minerals. Therefore, germanium's own minerals are extremely rare. Almost all of them are sulfosalts: germanite Cu 2 (Cu, Fe, Ge, Zn) 2 (S, As) 4 (6 - 10% Ge), argyrodite Ag 8 GeS 6 (3.6 - 7% Ge), confildite Ag 8 (Sn, Ge) S 6 (up to 2% Ge), etc. The bulk of germanium is dispersed in the earth's crust in a large number of rocks and minerals. So, for example, in some sphalerites, the content of germanium reaches kilograms per ton, in enargites up to 5 kg/t, in pyrargyrite up to 10 kg/t, in sulvanite and frankeite 1 kg/t, in other sulfides and silicates - hundreds and tens of g/t. t. Germanium is concentrated in deposits of many metals - in sulfide ores of non-ferrous metals, in iron ores, in some oxide minerals (chromite, magnetite, rutile, etc.), in granites, diabases and basalts. In addition, germanium is present in almost all silicates, in some deposits of coal and oil.
Receipt GermanyGermanium is obtained mainly from by-products of processing non-ferrous metal ores (zinc blende, zinc-copper-lead polymetallic concentrates) containing 0.001-0.1% Germany. Ash from coal combustion, dust from gas generators and waste from coke plants are also used as raw materials. Initially, germanium concentrate (2-10% Germany) is obtained from the listed sources in various ways, depending on the composition of the raw material. The extraction of germanium from concentrate usually involves the following steps:
1) chlorination of the concentrate with hydrochloric acid, its mixture with chlorine in an aqueous medium or other chlorinating agents to obtain technical GeCl 4 . To purify GeCl 4, rectification and extraction of impurities with concentrated HCl are used.
2) Hydrolysis of GeCl 4 and calcination of hydrolysis products to obtain GeO 2 .
3) Reduction of GeO 2 with hydrogen or ammonia to metal. 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 or by the Czochralski method.
GeO 2 + 4H 2 \u003d Ge + 2H 2 O
Semiconductor purity germanium with an impurity content of 10 -3 -10 -4% is obtained by zone melting, crystallization or thermolysis of the volatile GeH 4 monogermane:
GeH 4 \u003d Ge + 2H 2,
which is formed during the decomposition of compounds of active metals with Ge - germanides by acids:
Mg 2 Ge + 4HCl \u003d GeH 4 - + 2MgCl 2
Germanium occurs as an admixture in polymetallic, nickel, and tungsten ores, as well as in silicates. As a result of complex and time-consuming operations for the 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.
Purification and growth of germanium single crystals is carried out by zone melting.
Pure germanium dioxide was obtained for the first time in the USSR in early 1941. It was used to make germanium glass with a very high refractive index. Research on element No. 32 and methods for its possible production resumed after the war, in 1947. Now germanium was then of interest to Soviet scientists precisely as a semiconductor.
Physical properties GermanyBy appearance germanium is easily confused with silicon.
Germanium crystallizes in a diamond-type cubic structure, unit cell parameter a = 5.6575Å.
This element is not as strong as titanium or tungsten. The density of solid Germanium is 5.327 g/cm 3 (25°C); liquid 5.557 (1000°C); t pl 937.5°C; bp about 2700°C; thermal conductivity coefficient ~60 W/(m K), or 0.14 cal/(cm sec deg) at 25°C.
Germanium is almost as brittle as glass and can behave accordingly. Even at ordinary temperature, but above 550 ° C, it is amenable to plastic deformation. Hardness Germany on a mineralogical scale 6-6,5; compressibility coefficient (in the pressure range 0-120 Gn/m 2 , or 0-12000 kgf/mm 2) 1.4 10 -7 m 2 /mn (1.4 10 -6 cm 2 /kgf); surface tension 0.6 N/m (600 dynes/cm). Germanium is a typical semiconductor with a band gap of 1.104 10 -19 J or 0.69 eV (25°C); electrical resistivity high purity Germany 0.60 ohm-m (60 ohm-cm) at 25°C; the mobility of electrons is 3900 and the mobility of holes is 1900 cm 2 /v sec (25 ° C) (with an impurity content of less than 10 -8%).
All "unusual" modifications of crystalline germanium are superior to Ge-I and electrical conductivity. The mention of this particular property is not accidental: the value of electrical conductivity (or reciprocal value - resistivity) for a semiconductor element is especially important.
Chemical properties GermanyIn chemical compounds, germanium usually exhibits valences of 4 or 2. Compounds with a valence of 4 are more stable. Under normal conditions, it is resistant to air and water, alkalis and acids, soluble in aqua regia and in an alkaline solution of hydrogen peroxide. Germanium alloys and glasses based on germanium dioxide are used.
In chemical compounds, germanium usually exhibits valences of 2 and 4, with compounds of 4-valent germanium being more stable. At room temperature, germanium is resistant to air, water, alkali solutions, and dilute hydrochloric and sulfuric acids, but is easily soluble in aqua regia and in an alkaline solution of hydrogen peroxide. Nitric acid slowly oxidizes. When heated in air to 500-700°C, germanium is oxidized to GeO and GeO 2 oxides. Germany oxide (IV) - white powder with t pl 1116°C; solubility in water 4.3 g/l (20°C). According to its chemical properties, it is amphoteric, soluble in alkalis and with difficulty in mineral acids. It is obtained by calcining the hydrated precipitate (GeO 3 nH 2 O) released during the hydrolysis of GeCl 4 tetrachloride. By fusing GeO 2 with other oxides, derivatives of germanic acid can be obtained - metal germanates (Li 2 GeO 3, Na 2 GeO 3 and others) - solids with high temperatures melting.
When germanium reacts with halogens, the corresponding tetrahalides are formed. The reaction proceeds most easily with fluorine and chlorine (already at room temperature), then with bromine (weak heating) and iodine (at 700-800°C in the presence of CO). One of the most important compounds Germany GeCl 4 tetrachloride is a colorless liquid; t pl -49.5°C; bp 83.1°C; density 1.84 g/cm 3 (20°C). Water strongly hydrolyzes with the release of a precipitate of hydrated oxide (IV). It is obtained by chlorination of metallic Germany or by the interaction of GeO 2 with concentrated HCl. Also known are Germany dihalides of the general formula GeX 2 , GeCl monochloride, Ge 2 Cl 6 hexachlorodigermane, and Germany oxychlorides (for example, CeOCl 2).
Sulfur reacts vigorously with Germany at 900-1000°C to form GeS 2 disulfide, a white solid, mp 825°C. GeS monosulfide and similar compounds of Germany with selenium and tellurium, which are semiconductors, are also described. Hydrogen slightly reacts with germanium at 1000-1100°C to form germine (GeH) X, an unstable and easily volatile compound. By reacting germanides with dilute hydrochloric acid, germanohydrogens of the series Ge n H 2n+2 up to Ge 9 H 20 can be obtained. Germylene composition GeH 2 is also known. Germanium does not directly react with nitrogen, however, there is Ge 3 N 4 nitride, which is obtained by the action of ammonia on Germanium at 700-800°C. Germanium does not interact with carbon. Germanium forms compounds with many metals - germanides.
Numerous complex compounds of germany are known, which are becoming increasingly important both in the analytical chemistry of germanium and in the processes of its preparation. Germanium forms complex compounds with organic hydroxyl-containing molecules (polyhydric alcohols, polybasic acids, and others). Heteropolyacids Germany were obtained. As well as for other elements of group IV, Germany is characterized by the formation of organometallic compounds, an example of which is tetraethylgermane (C 2 H 5) 4 Ge 3.
Compounds of divalent germanium.Germanium(II) hydride GeH 2 . White unstable powder (in air or in oxygen it decomposes with an explosion). Reacts with alkalis and bromine.
Germanium (II) monohydride polymer (polygermine) (GeH 2) n . Brownish black powder. Poorly soluble in water, instantly decomposes in air and explodes when heated to 160 ° C in a vacuum or in an inert gas atmosphere. Formed during the electrolysis of sodium germanide NaGe.
Germanium(II) oxide GeO. Black crystals with basic properties. Decomposes at 500°C into GeO 2 and Ge. Slowly oxidizes in water. Slightly soluble in hydrochloric acid. Shows restorative properties. Obtained by the action of CO 2 on metallic germanium, heated to 700-900 ° C, alkalis - on germanium (II) chloride, by calcining Ge (OH) 2 or by reducing GeO 2.
Germanium hydroxide (II) Ge (OH) 2. Red-orange crystals. When heated, it turns into GeO. Shows amphoteric character. Obtained by treatment of germanium (II) salts with alkalis and hydrolysis of germanium (II) salts.
Germanium(II) fluoride GeF 2 . Colorless hygroscopic crystals, t pl =111°C. Obtained by the action of GeF 4 vapors on germanium metal when heated.
Germanium (II) chloride GeCl 2 . Colorless crystals. t pl \u003d 76.4 ° C, t bp \u003d 450 ° C. At 460°С, it decomposes into GeCl 4 and metallic germanium. Hydrolyzed by water, slightly soluble in alcohol. Obtained by the action of GeCl 4 vapors on germanium metal when heated.
Germanium (II) bromide GeBr 2. Transparent needle crystals. t pl \u003d 122 ° C. Hydrolyzes with water. Slightly soluble in benzene. Soluble in alcohol, acetone. Obtained by the interaction of germanium (II) hydroxide with hydrobromic acid. When heated, it disproportionates into metallic germanium and germanium (IV) bromide.
Germanium (II) iodide GeI 2 . Yellow hexagonal plates, diamagnetic. t pl =460 about C. Slightly soluble in chloroform and carbon tetrachloride. When heated above 210°C, it decomposes into metallic germanium and germanium tetraiodide. Obtained by the reduction of germanium (II) iodide with hypophosphoric acid or by thermal decomposition of germanium tetraiodide.
Germanium(II) sulfide GeS. Received by dry way - greyish-black brilliant rhombic opaque crystals. t pl \u003d 615 ° C, density is 4.01 g / cm 3. Slightly soluble in water and ammonia. Soluble in potassium hydroxide. Received wet - red-brown amorphous precipitate, the density is 3.31 g/cm 3 . Soluble in mineral acids and ammonium polysulfide. Obtained by heating germanium with sulfur or passing hydrogen sulfide through a germanium (II) salt solution.
Compounds of tetravalent germanium.Germanium(IV) hydride GeH 4 . Colorless gas (density is 3.43 g/cm 3 ). It is poisonous, smells very unpleasant, boils at -88 o C, melts at about -166 o C, thermally dissociates above 280 o C. Passing GeH 4 through a heated tube, a shiny mirror of metallic germanium is obtained on its walls. Obtained by the action of LiAlH 4 on germanium (IV) chloride in ether or by treating a solution of germanium (IV) chloride with zinc and sulfuric acid.
Germanium oxide (IV) GeO 2. It exists in the form of two crystalline modifications (hexagonal with a density of 4.703 g / cm 3 and tetrahedral with a density of 6.24 g / cm 3). Both are air resistant. Slightly soluble in water. t pl \u003d 1116 ° C, t kip \u003d 1200 ° C. Shows amphoteric character. It is reduced by aluminum, magnesium, carbon to metallic germanium when heated. Obtained by synthesis from elements, calcination of germanium salts with volatile acids, oxidation of sulfides, hydrolysis of germanium tetrahalides, treatment of alkali metal germanites with acids, metallic germanium with concentrated sulfuric or nitric acids.
Germanium (IV) fluoride GeF 4 . A colorless gas that smokes in air. t pl \u003d -15 about C, t kip \u003d -37 ° C. Hydrolyzes with water. Obtained by decomposition of barium tetrafluorogermanate.
Germanium (IV) chloride GeCl 4 . Colorless liquid. t pl \u003d -50 o C, t kip \u003d 86 o C, density is 1.874 g / cm 3. Hydrolyzed by water, soluble in alcohol, ether, carbon disulfide, carbon tetrachloride. Obtained by heating germanium with chlorine and passing hydrogen chloride through a suspension of germanium oxide (IV).
Germanium (IV) bromide GeBr 4 . Octahedral colorless crystals. t pl \u003d 26 o C, t kip \u003d 187 o C, density is 3.13 g / cm 3. Hydrolyzes with water. Soluble in benzene, carbon disulfide. Obtained by passing bromine vapor over heated metallic germanium or by the action of hydrobromic acid on germanium (IV) oxide.
Germanium (IV) iodide GeI 4 . Yellow-orange octahedral crystals, t pl \u003d 146 ° C, t kip \u003d 377 ° C, density is 4.32 g / cm 3. At 445 ° C, it decomposes. Soluble in benzene, carbon disulfide, and hydrolyzed by water. In air, it gradually decomposes into germanium (II) iodide and iodine. Attaches ammonia. Obtained by passing iodine vapor over heated germanium or by the action of hydroiodic acid on germanium (IV) oxide.
Germanium (IV) sulfide GeS 2. White crystalline powder, t pl \u003d 800 ° C, density is 3.03 g / cm 3. Slightly soluble in water and slowly hydrolyzes in it. Soluble in ammonia, ammonium sulfide and alkali metal sulfides. It is obtained by heating germanium (IV) oxide in a stream of sulfur dioxide with sulfur or by passing hydrogen sulfide through a solution of germanium (IV) salt.
Germanium sulfate (IV) Ge (SO 4) 2. Colorless crystals, density is 3.92 g/cm 3 . It decomposes at 200 o C. It is reduced by coal or sulfur to sulfide. Reacts with water and alkali solutions. Obtained by heating germanium (IV) chloride with sulfur oxide (VI).
Isotopes of germaniumThere are five isotopes found in nature: 70 Ge (20.55% wt.), 72 Ge (27.37%), 73 Ge (7.67), 74 Ge (36.74%), 76 Ge (7.67% ). The first four are stable, the fifth (76 Ge) undergoes double beta decay with a half-life of 1.58×10 21 years. In addition, there are two "long-lived" artificial ones: 68 Ge (half-life 270.8 days) and 71 Ge (half-life 11.26 days).
Application of germanium
Germanium is used in the manufacture of optics. Due to its transparency in the infrared region of the spectrum, metallic ultra-high purity germanium is of strategic importance in the production of optical elements for infrared optics. In radio engineering, germanium transistors and detector diodes have characteristics different from silicon ones, due to the lower pn-junction trigger voltage in germanium - 0.4V versus 0.6V for silicon devices.
For more details, see the article application of germanium.
The biological role of germaniumGermanium is found in animals and plants. Small amounts of germanium have no physiological effect on plants, but are toxic in large amounts. Germanium is non-toxic to molds.
For animals, germanium has low toxicity. Germanium compounds have not been found to have a pharmacological effect. The permissible concentration of germanium and its oxide in the air is 2 mg / m³, that is, the same as for asbestos dust.
Divalent germanium compounds are much more toxic.
In experiments determining the distribution of organic germanium in the body 1.5 hours after its oral administration, the following results were obtained: a large amount of organic germanium is found in the stomach, small intestine, bone marrow, spleen, and blood. Moreover, its high content in the stomach and intestines shows that the process of its absorption into the blood has a prolonged effect.
The high content of organic germanium in the blood allowed Dr. Asai to put forward the following theory of the mechanism of its action in the human body. It is assumed that organic germanium in the blood behaves similarly to hemoglobin, which also carries a negative charge and, like hemoglobin, participates in the process of oxygen transfer in body tissues. This prevents the development of oxygen deficiency (hypoxia) at the tissue level. Organic germanium prevents the development of the so-called blood hypoxia, which occurs when the amount of hemoglobin that can attach oxygen decreases (a decrease in the oxygen capacity of the blood), and develops with blood loss, carbon monoxide poisoning, and radiation exposure. The most sensitive to oxygen deficiency are the central nervous system, the heart muscle, the tissues of the kidneys, and the liver.
As a result of the experiments, it was also found that organic germanium promotes the induction of gamma interferons, which suppress the reproduction of rapidly dividing cells and activate specific cells (T-killers). The main areas of action of interferons at the level of the organism are antiviral and antitumor protection, immunomodulatory and radioprotective functions of the lymphatic system.
In the process of studying pathological tissues and tissues with primary signs of disease, it was found that they are always characterized by a lack of oxygen and the presence of positively charged hydrogen radicals H + . Ions H + have an extremely negative impact on the cells of the human body, up to their death. Oxygen ions, having the ability to combine with hydrogen ions, make it possible to selectively and locally compensate for damage to cells and tissues caused by hydrogen ions. The action of germanium on hydrogen ions is due to its organic form - the form of sesquioxide. In preparing the article, materials of Suponenko A.N. were used.
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, similar in appearance 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 is larger in nature 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 along the way 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 complicated ways, 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 cooler. 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.
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