Inorganic polymer materials. Tellurium chain structure

52. Polymers, plastics Polymers are substances whose macromolecules consist of numerous repeating elementary units that represent the same group of atoms. The molecular weight of molecules ranges from 500 to 1,000,000. Polymer molecules are divided into

Theoretically, the existence of inorganic polymers formed by chemical elements of groups III-VI of the element system is possible.

The most important chemical element for creating inorganic polymers is oxygen, the most abundant element on earth. It easily creates heterochain elementooxane high molecular weight compounds, so polyelementoxanes are the main class of heterochain carbon-free, or inorganic, polymers.

Inorganic polymers include all carbon-free polyelementoxanes with bonds such as P-O, B-O, S-O, Si-O, Al-O, etc., as well as many carbon-free heteronuclear compounds such as borides, sulfides, silicides, carbides, etc.

It is generally accepted that high-molecular compounds include substances consisting of atoms linked into a macromolecular structure by covalent bonds. It has been established that the content of covalent bonds in inorganic polymers ranges from 50 to 80%.

Macromolecules of inorganic polymers can be not only heterochain, but also homoatomic. Organic homoatomic polymers of carbon are well known - diamond and graphite, which were discussed above (Chapter 4).

Less known are homoatomic inorganic polymers of sulfur, selenium, and tellurium. Homoatomic sulfur polymers have a molecular weight from 5000 to 300,000, a glass transition temperature of 248-250 K and exhibit highly elastic properties at temperatures of 273-353 K. But most chemical elements are not capable of forming stable homoatomic high-molecular compounds.

Heterochain inorganic polymers are much more widely known. Due to their structure, they are more stable and resistant to various influences.

Heterochain inorganic polymers, like organic ones, can have a linear and network structure. Linear glasses include silicate glasses based on silicon oxide, polyphosphates and polyborates (compounds based on salts of polyphosphoric and polyboric acids, respectively). The high-molecular nature of silicates, our great compatriot D.I. Mendeleev predicted back in the 19th century. and wrote about silica as a polymer.

Another inorganic heterochain polymer based on silicon dioxide, quartz, has a three-dimensional network structure.

Other natural inorganic polymeric materials based on silicates are well known - asbestos, mica, talc. Technologies for the synthesis of these polymers have been developed, and the technical characteristics of artificial materials are higher than those of natural ones.

The most important group of inorganic heterochain polymer materials consists of ceramics of various compositions.

What allows us to consider these materials to be polymeric? First of all, the presence of high anisotropy of the macromolecule and the connection of atoms with each other by strong covalent bonds. Along with this, for carbon-free polymers, as well as for organic polymers, the gaseous state is unknown. Just like organic high-molecular compounds, carbon-free polymers are divided into thermoplastics (for example, silicate glasses) and thermosets (for example, oxide ceramics).

Solutions and melts of inorganic polymers, compared to solutions of low molecular weight substances, have increased viscosity, which increases with increasing molecular weight. Networked inorganic polymers, like networked organic polymers, are not capable of dissolution.

Inorganic polymeric materials with a linear structure are capable of being in three physical states: glassy, ​​highly elastic and viscous. In Fig. Figure 17.1 shows thermomechanical curves for organic and inorganic polymers. The curves were constructed by measuring the torsion angle f of a round rod made of the material under study at different temperatures.

From the data presented it is clear that inorganic glasses, like organic polymers, have two temperature transitions:

Rice. 17.1. Thermomechanical curves of organic and inorganic polymers: 1 - plexiglass; 2- ebonite; 3, 4, 5 - silicate glasses (lead, alkaline and low-alkaline, respectively)

yes, at which their properties (in this case, the angle of twist of the rod) change sharply, which is associated with their transitions from a glassy to a highly elastic state and from a highly elastic to a viscous flow state.

Many inorganic polymers have a network structure and, like organic thermosets, cannot exhibit high elasticity. For networked inorganic polymers, as well as for organic polymers that have a three-dimensional network, the concept of “macromolecule” loses its meaning, since all their atoms are connected into a single network structure, forming a giant supermacromolecule.

The technology for producing inorganic high-molecular compounds, as well as organic ones, is based on polymerization and polycondensation. The synthesis of inorganic polymers with a network structure and the molding of products from them occur simultaneously, just as in the manufacture of products from thermosets.

Plasticization of inorganic polymers is carried out with low molecular weight substances and makes it possible to reduce the glass transition temperature, similar to what happens when plasticizing organic polymers with organic plasticizers. Water, alcohols, ammonia, and gases such as nitrogen and oxygen are used as plasticizers for inorganic polymers, which reduce the level of intermolecular interaction and increase the interval between the glass transition and fluidity temperatures.

Inorganic polymers tend to form supramolecular structures. Using various methods, it has been established that the glass structure contains microinhomogeneities that are strictly ordered. There is one structurally ordered element in glass per volume 1(G 28 cm 3 . The sizes of such elements, as a rule, are extremely small (from 1 to 300 nm), so they do not have a significant effect on the properties of glasses. In some materials, with the help of nuclei Crystallization specifically creates a two-phase amorphous-crystalline structure, which makes it possible to obtain materials with specified properties.

In Fig. Figure 17.2 shows photographs of the microstructure of inorganic polymers based on metal oxides, in which supramolecular formations are clearly visible, indicating the structural ordering of these materials.

Rice. 17.2. Supramolecular structures of inorganic polymers (x10,000): A- fuel pellet U0 2; b- spinels MgAl 2 0 4

Macromolecules of carbon-free linear polyelementoxanes, like organic polymers, are flexible. The widespread opinion about the lack of flexibility in macromolecules of inorganic polymers is based on the fact that most carbon-free natural polymers (silicates) have a three-dimensional structure that strictly limits the segmental mobility of macromolecules.

The physical and chemical properties of inorganic polymers are fundamentally different from the properties of organic and organoelement polymers, which is a consequence of differences in the structure of the main chain. They have high strength and hardness, refractoriness and heat resistance, wear resistance and excellent dielectric properties, and are chemically and biologically inert.

Due to these properties, inorganic polymers are widely used as fire-resistant, heat-resistant and ultra-strong structural materials. They are used to make catalysts and adsorbents, adhesives and sealants with high heat resistance; these materials are used in the manufacture of laser and electronic equipment. Inorganic polymers are widely used as building materials, as well as in orthopedics and dentistry. And this is just the beginning.

Table 17.1.Forecast for the development of research and development in the field of ceramic materials and glass

In table 17.1 shows forecasts for the development of research in the field of inorganic polymer materials, which show that this area of ​​materials science should lead to revolutionary changes in the field of creating new technology.

Further development of the use of these materials is associated with the need to reduce their cost and expand production volumes.

Security questions

• 1. What chemical elements can form inorganic polymeric materials?
• 2. What bonds connect atoms in inorganic polymeric materials?
• 3. Give examples of inorganic structural materials.
• 4. What are the most important properties inherent in high-molecular compounds that inorganic polymers have?
• 5. What physical states are known for inorganic polymers?
• 6. How can inorganic polymers be classified in relation to heating?
• 7. Is it possible to plasticize inorganic polymers?
• 8. Is the concept of supramolecular structure applicable to inorganic polymers?
• 9. What are the distinctive properties of inorganic structural materials?

There is practically no person in the modern world who does not have at least some idea about polymers. Polymers go through life with a person, making his life more and more convenient and comfortable. When mentioning polymers, the first associations will be with synthetic organic substances, since they are more visible. Natural polymers - natural organic substances - although there are more of them in the world around us, in the associative perception of a person they fade into the background. They always surround us, but no one thinks about the nature of the origin of flora and fauna. Cellulose, starch, lignin, rubber, proteins and nucleic acids are the main materials used by nature to create the animal and plant world around us. And absolutely no one will perceive precious stones, graphite, mica, sand and clay, glass and cement as polymers. Nevertheless, science has established the fact of the polymeric structure of many inorganic compounds, including those listed above. Polymer substances consist of macromolecules. When polymers are formed, a large number of atoms or groups of atoms are bonded to each other by chemical bonds - covalent or coordination. Polymer macromolecules contain tens, hundreds, thousands or tens of thousands of atoms or repeating elementary units. Information about the polymer structure was obtained by studying the properties of solutions, the structure of crystals, and the mechanical and physicochemical properties of inorganic substances. In support of the above, it should be noted that there is a sufficient amount of scientific literature confirming the fact of the polymeric structure of some inorganic substances.

A logical remark would be: why is there so much information about synthetic organic polymers and so little about inorganic ones? If there are inorganic polymeric substances, what exactly are they and where are they used? Several examples of inorganic polymers were given above. These are well-known substances that everyone knows, but few people know that these substances can be classified as polymers. By and large, the average person doesn’t care whether graphite can be classified as a polymer or not; as for precious stones, for some it may even be offensive to equate expensive jewelry with cheap plastic jewelry. Nevertheless, if there is reason to call some inorganic substances polymers, then why not talk about it. Let's look at some representatives of such materials and look in more detail at the most interesting ones.
The synthesis of inorganic polymers most often requires very pure starting materials, as well as high temperatures and pressures. The main methods for their production, like organic polymers, are polymerization, polycondensation and polycoordination. The simplest inorganic polymers include homochain compounds consisting of chains or frameworks built from identical atoms. In addition to the well-known carbon, which is the main element involved in the construction of almost all organic polymers, other elements can also participate in the construction of macromolecules. These elements include boron from the third group, silicon, germanium and tin from the fourth group, which also includes carbon, phosphorus, arsenic, antimony and bismuth from the fifth group, sulfur, selenium, tellurium from the sixth. Mainly homochain polymers obtained from these elements are used in electronics and optics. The electronics industry is developing at a very high pace and the demand for synthetic crystals has long exceeded supply. Of particular note, however, is carbon and the inorganic polymers that are produced on its basis: diamond and graphite. Graphite is a well-known material that has found application in various industries. Pencils, electrodes, crucibles, paints, and lubricants are made from graphite. Thousands of tons of graphite go to the needs of the nuclear industry due to its properties to slow down neutrons. In the article we will dwell in more detail on the most interesting representatives of inorganic polymers - precious stones.
The most interesting, pretentious, and beloved by women representative of inorganic polymers are diamonds. Diamonds are very expensive minerals, which can also be classified as inorganic polymers; they are mined in nature by five large companies: DeBeers, Alrosa, Leviev, BHPBilliton, RioTinto. It was the DeBeers company that created the reputation of these stones. Smart marketing boils down to the slogan, “forever.” DeBeers has turned this stone into a symbol of love, prosperity, power, and success. An interesting fact is that diamonds are found quite often in nature, for example sapphires and rubies, which are rarer minerals, but they are valued lower than diamonds. The most interesting thing is the situation that has developed in the natural diamond market. The fact is that there are technologies that make it possible to obtain synthetic diamonds. In 1954, General Electric researcher Tracy Hall invented a device that made it possible to obtain diamond crystals from iron sulfide at a pressure of 100,000 atmospheres and a temperature of over 2500ºC. The quality of these stones was not high from a jewelry point of view, but the hardness was the same as that of natural stone. Hall's invention was improved and in 1960 General Electric created a plant in which it was possible to produce gem-quality diamonds. The negative point was that the price of synthetic stones was higher than natural ones.
At the moment, there are two technologies for synthesizing diamonds. HPHT (high pressure/high temperature) technology is the synthesis of diamonds in a combination of high pressure and high temperature. CVD (chemical vapor deposition) technology is a chemical vapor deposition technology that is considered more progressive and allows you to grow diamond, as if simulating the natural conditions of its growth. Both technologies have advantages and disadvantages. Campaigns using them solve the shortcomings of technology by using their own inventions and developments. For example, back in 1989, a group of Soviet scientists from Novosibirsk managed to reduce the fusion pressure to 60,000 atmospheres. After the collapse of the Soviet Union, developments in the field of diamond synthesis continued, thanks to many foreign investors interested in obtaining the technology for cheap synthesis of high-quality gemstones. For example, DeBeers, in order not to lose the opportunity to control the market, financed the work of some scientists. Some private entrepreneurs bought diamond synthesis equipment in Russia, for example, the now thriving American company Gemesis began by purchasing a diamond growing installation in Russia in 1996 for $60,000. Now Gemesis produces and sells diamonds of rare colors: yellow and blue, and the difference in price between these and exactly the same natural stones reaches 75%.

Another large company synthesizing diamonds, Apollo Diamond, is improving HPHT technology by synthesizing stones in a gas atmosphere of a certain composition (symbiosis technology of HPHT and CVD). This method brings Apollo Diamond to the market of jewelry stones; at the same time, the quality of synthetic diamonds grown using this technology is very high. It is increasingly difficult for gemotologists to distinguish synthetic stones from natural ones. This requires a complex of analyzes using fairly complex and expensive equipment. Apollo Diamond synthetic gem diamonds are almost impossible to distinguish from natural minerals using standard analysis methods.

World diamond production is now 115 million carats or 23 tons per year. Theoretically, this gigantic market could collapse and the reputation of diamonds as precious stones would be lost forever. Monopoly firms invest in stabilizing the situation and controlling the market. For example, expensive marketing campaigns are carried out, patents for artificial diamond manufacturing technologies are purchased so that these technologies are never introduced, certificates and quality passports are issued for branded diamonds confirming their natural origin. But will this hold back the progress of fusion technology?

Having talked about diamonds, we were distracted by the brilliance of the precious stones of the jewelry industry, but we should also point out industrial stones. In this case, most diamond growing enterprises operate primarily for the needs of the electronics and optical industries. The industrial stone market may not be as intriguing as the jewelry market, but it is nonetheless huge. For example, Apollo Diamond's main income is the synthesis of thin diamond disks for semiconductors. By the way, now a diamond synthesis installation with a productivity of about 200 kg of diamonds per month can be purchased for 30 thousand dollars.

Another representative of precious stones is ruby. The first synthetic ruby ​​was born in 1902. It was synthesized by the French engineer Verneuil by melting aluminum oxide and chromium powder, which then crystallized into a six-gram ruby. This simplicity of synthesis allowed the relatively rapid development of industrial production of rubies around the world. This stone is in great demand. Every year about 5 tons of rubies are mined in the world, and market needs amount to hundreds of tons. Rubies are needed in the watch industry and in the production of lasers. The technology proposed by Verneuil subsequently provided the prerequisites for the synthesis of sapphires and garnets. The largest productions of artificial rubies are located in France, Switzerland, Germany, Great Britain, and the USA. The economics of production are as follows. The lion's share of the cost is consumed by energy costs. At the same time, the cost of synthesizing a kilogram of rubies is 60 dollars, the cost of a kilogram of sapphires is 200 dollars. The profitability of such a business is very high, since the purchase price for crystals is at least twice as high. Here a number of factors should be taken into account, such as the fact that the larger the grown single crystal, the lower its cost; also, when producing products from crystals, their price will be much higher than the price of sold crystals (for example, the production and sale of glass). As for equipment, Russian installations for growing crystals cost about 50 thousand dollars, Western ones are an order of magnitude more expensive, while the payback period for organized production is on average two years. As already mentioned, the market needs for synthetic crystals are colossal. For example, sapphire crystals are in great demand. About a thousand tons of sapphires are synthesized around the world per year. Annual production needs reach a million tons!
Emeralds are synthesized exclusively for the needs of the jewelry industry. Unlike other crystals, emerald is obtained not from a melt, but from a solution of boron ahydride at a temperature of 400 ° C and a pressure of 500 atmospheres in a hydrothermal chamber. It is curious that the extraction of natural stone is only 500 kilograms per year. Synthetic emeralds are also produced in the world in quantities that are not as large as other crystals, about a ton per year. The fact is that the technology for synthesizing emeralds is low-productivity, but the profitability of such production is high. Producing about 5 kilograms of crystals per month at a cost of $200 per kilogram, the selling price of synthetic emeralds is almost equal to the price of natural ones. The cost of the installation for the synthesis of emeralds is about 10 thousand dollars.
But the most popular synthetic crystal is silicon. Perhaps it will give odds to any precious stone. At the moment, silicon occupies 80% of the total market for synthetic crystals. The market is experiencing a shortage of silicon due to the rapid development of high technologies. At the moment, the profitability of silicon production exceeds 100%. The price of a kilogram of silicon is about $100 per kilogram, while the cost of synthesis reaches $25.

Ultrapure silicon is used as a semiconductor. Solar photocells with a high efficiency are made from its crystals. Silicon, like carbon, can create long molecular chains from its atoms. In this way, silane and rubber are obtained, which have amazing properties. Several years ago, the whole world was excited by the news of the experiments of the American engineer Walter Robbs, who managed to produce a film of silicone rubber 0.0025 centimeters thick. He covered the cage in which the hamster lived with this rubber and lowered the hamster into the aquarium. For several hours, the world's first submarine hamster breathed oxygen dissolved in water, and was alert and showed no signs of anxiety. It turns out that the film plays the role of a membrane, performing the same functions as the gills of fish. The film allows life gas molecules inside, while carbon dioxide is forced out through the film. This discovery makes it possible to organize human life under water by moving aside cylinders with a breathing mixture and oxygen generators.

Silicon comes in three types: metallurgical silicon (MG), electronics grade silicon (EG), and solar grade silicon (SG). Due to a series of energy crises, alternative energy technologies are being intensively introduced. These include the conversion of solar energy into electrical energy, that is, the use of solar installations powered by solar batteries. An important component of solar cells is silicon. In Ukraine, the Zaporozhye titanium-magnesium plant produced silicon for solar batteries. Under the Soviet Union, this enterprise produced 200 tons of silicon, with the all-Union production volume being 300 tons. The author currently knows nothing about the situation with silicon production in Zaporozhye. The cost of organizing a modern production of polycrystalline silicon for the needs of the energy industry with a capacity of 1000 tons per year is about 56 million dollars. The synthesis of silicon for various needs throughout the world ranks first in demand and will hold this position for a long time.

In the article we examined only some representatives of inorganic polymers. Perhaps many of the things told above were perceived by some with surprise and genuine interest. Someone took a fresh look at the concept of the philosopher's stone; even if it is not gold, it is still possible to obtain precious stones from nondescript metal oxides and other unremarkable substances. We hope that the article gave rise to thought and at least entertained the reader with interesting facts.

Inorganic polymers

• Inorganic polymers- polymers that do not contain C-C bonds in the repeating unit, but are capable of containing an organic radical as side substituents.

Classification of polymers

1. Homochain polymers

Carbon and chalcogens (plastic modification of sulfur).

Mineral fiber asbestos

Characteristics of asbestos

• Asbestos(Greek ἄσβεστος, - indestructible) is the collective name for a group of fine-fiber minerals from the class of silicates. Consist of the finest flexible fibers.

• Ca2Mg5Si8O22(OH)2 - formula

• The two main types of asbestos are serpentine asbestos (chrysotile asbestos, or white asbestos) and amphibole asbestos.

Chemical composition

• In terms of their chemical composition, asbestos is aqueous silicates of magnesium, iron, and partly calcium and sodium. The following substances belong to the class of chrysotile asbestos:

• Mg6(OH)8

• 2Na2O*6(Fe,Mg)O*2Fe2O3*17SiO2*3H2O

Safety

• Asbestos is practically inert and does not dissolve in body fluids, but has a noticeable carcinogenic effect. People involved in asbestos mining and processing are several times more likely to develop tumors than the general population. Most often it causes lung cancer, tumors of the peritoneum, stomach and uterus.

• Based on the results of extensive scientific research into carcinogens, the International Agency for Research on Cancer has classified asbestos as one of the most dangerous carcinogens in the first category.

Application of asbestos

• Production of fire-resistant fabrics (including for sewing suits for firefighters).

• In construction (as part of asbestos-cement mixtures for the production of pipes and slate).

• In places where it is necessary to reduce the influence of acids.

The role of inorganic polymers in the formation of the lithosphere

Lithosphere

• Lithosphere- the hard shell of the Earth. It consists of the earth's crust and the upper part of the mantle, up to the asthenosphere.

The lithosphere beneath oceans and continents varies considerably. The lithosphere beneath the continents consists of sedimentary, granite and basalt layers with a total thickness of up to 80 km. The lithosphere under the oceans has undergone many stages of partial melting as a result of the formation of the oceanic crust, it is greatly depleted in fusible rare elements, mainly consists of dunites and harzburgites, its thickness is 5-10 km, and the granite layer is completely absent.

Chemical composition

The main components of the Earth's crust and surface soil of the Moon are Si and Al oxides and their derivatives. This conclusion can be made based on existing ideas about the prevalence of basalt rocks. The primary substance of the earth's crust is magma - a fluid form of rock that contains, along with molten minerals, a significant amount of gases. When magma reaches the surface, it forms lava, which solidifies into basalt rocks. The main chemical component of lava is silica, or silicon dioxide, SiO2. However, at high temperatures, silicon atoms can easily be replaced by other atoms, such as aluminum, forming various types of aluminosilicates. In general, the lithosphere is a silicate matrix with the inclusion of other substances formed as a result of physical and chemical processes that occurred in the past under conditions of high temperature and pressure. Both the silicate matrix itself and the inclusions in it contain predominantly substances in polymer form, that is, heterochain inorganic polymers.

Granite

• Granite - silicic igneous intrusive rock. It consists of quartz, plagioclase, potassium feldspar and micas - biotite and muscovite. Granites are very widespread in the continental crust.

The largest volumes of granites are formed in collision zones, where two continental plates collide and thickening of the continental crust occurs. According to some researchers, a whole layer of granite melt is formed in the thickened collision crust at the level of the middle crust (depth 10-20 km). In addition, granitic magmatism is characteristic of active continental margins, and to a lesser extent, of island arcs.

• Mineral composition of granite:

• feldspars - 60-65%;

• quartz - 25-30%;

• dark-colored minerals (biotite, rarely hornblende) - 5-10%.

Basalt

• Mineral composition. The main mass is composed of microlites of plagioclase, clinopyroxene, magnetite or titanomagnetite, as well as volcanic glass. The most common accessory mineral is apatite.

• Chemical composition. The silica content (SiO2) ranges from 45 to 52-53%, the sum of alkaline oxides Na2O+K2O up to 5%, in alkaline basalts up to 7%. Other oxides can be distributed as follows: TiO2 = 1.8-2.3%; Al2O3=14.5-17.9%; Fe2O3=2.8-5.1%; FeO=7.3-8.1%; MnO=0.1-0.2%; MgO=7.1-9.3%; CaO=9.1-10.1%; P2O5=0.2-0.5%;

Quartz (Silicon(IV) Oxide, Silica)

Formula: SiO2

• Formula: SiO2

• Color: colorless, white, violet, gray, yellow, brown

• Trait Color: white

• Shine: glassy, ​​sometimes greasy in solid masses

• Density: 2.6-2.65 g/cm³

• Hardness: 7

Chemical properties

Corundum (Al2O3, alumina)

Formula: Al2O3

• Formula: Al2O3

• Color: blue, red, yellow, brown, gray

• Trait Color: white

• Shine: glass

• Density: 3.9-4.1 g/cm³

• Hardness: 9

Tellurium

Tellurium chain structure

• Crystals are hexagonal, the atoms in them form helical chains and are connected by covalent bonds to their nearest neighbors. Therefore, elemental tellurium can be considered an inorganic polymer. Crystalline tellurium is characterized by a metallic luster, although due to its complex of chemical properties it can rather be classified as a non-metal.

Applications of tellurium

• Production of semiconductor materials

• Rubber production

• High temperature superconductivity

Selenium

Selenium chain structure

Black Gray Red

Gray selenium

Gray selenium (sometimes called metallic) has crystals in a hexagonal system. Its elementary lattice can be represented as a slightly deformed cube. All its atoms seem to be strung on spiral-shaped chains, and the distances between neighboring atoms in one chain are approximately one and a half times less than the distance between the chains. Therefore, the elementary cubes are distorted.

Applications of gray selenium

• Ordinary gray selenium has semiconducting properties; it is a p-type semiconductor, i.e. conductivity in it is created mainly not by electrons, but by “holes”.

• Another practically very important property of semiconductor selenium is its ability to sharply increase electrical conductivity under the influence of light. The action of selenium photocells and many other devices is based on this property.

Red selenium

• Red selenium is a less stable amorphous modification.

• A polymer with a chain structure but a poorly ordered structure. In the temperature range of 70-90°C, it acquires rubber-like properties, turning into a highly elastic state.

• Does not have a specific melting point.

• Red amorphous selenium with increasing temperature (-55) it begins to transform into gray hexagonal selenium

Sulfur

Structural features

• The plastic modification of sulfur is formed by helical chains of sulfur atoms with left and right axes of rotation. These chains are twisted and pulled in one direction.

• Plastic sulfur is unstable and spontaneously turns into rhombic sulfur.

Obtaining plastic sulfur

Application of sulfur

• Preparation of sulfuric acid;

• In the paper industry;

• in agriculture (to combat plant diseases, mainly grapes and cotton);

• in the production of dyes and luminous compositions;

• to obtain black (hunting) powder;

• in the production of matches;

• ointments and powders for the treatment of certain skin diseases.

Allotropic modifications of carbon

Comparative characteristics

Application of allotropic modifications of carbon

• Diamond - in industry: it is used to make knives, drills, cutters; in jewelry making. The future is the development of microelectronics on diamond substrates.

• Graphite – for the manufacture of melting crucibles, electrodes; plastic filler; neutron moderator in nuclear reactors; component of the composition for the manufacture of leads for black graphite pencils (mixed with kaolin)