Amorphous substances. Crystalline and amorphous state of matter. The use of amorphous substances

Have you ever thought about what mysterious amorphous substances are? In structure, they differ from both solid and liquid. The fact is that such bodies are in a special condensed state, which has only short-range order. Examples of amorphous substances - resin, glass, amber, rubber, polyethylene, polyvinyl chloride (our favorite plastic windows), various polymers and others. These are solids that do not have a crystal lattice. Still to them it is possible to carry a sealing wax, various glues, ebonite and plastics.

Unusual properties of amorphous substances

During the splitting in amorphous bodies , faces are not formed. The particles are completely disorderly and are at a close distance to each other. They can be either thick or viscous. How are external influences influenced by them? Under the influence of various temperatures, the bodies become fluid, like liquids, and at the same time quite elastic. In the case when the external effect does not last long, the substances of the amorphous structure can split into pieces in a powerful attack. Long-term influence from the outside leads to the fact that they are simply flowing.

Try a small experiment at home using resin. Put it on a hard surface, and you will notice that it starts to flow smoothly. That's right, it's an amorphous substance! The speed depends on the temperature. If it is very high, the resin will begin to flow noticeably faster.

What else is typical for such bodies? They can take any form. If the amorphous substances in the form of small particles are placed in a vessel, for example, in a jug, they will also take the form of a vessel. They are also isotropic, that is, they exhibit the same physical properties in all directions.

Melting and transition to other states. Metal and glass

The amorphous state of the substance does not imply the maintenance of any particular temperature. At low indices, the body freezes, at high temperatures it melts. By the way, the degree of viscosity of such substances also depends on this. Low temperature promotes reduced viscosity, high, on the contrary, it increases.

For substances of the amorphous type, one more feature can be singled out: transition to the crystalline state, and spontaneous. Why is this happening? The internal energy in the crystalline body is much less than in the amorphous one. We can see this on the example of glass products - over time, the glass becomes cloudy.

Metal glass - what is it? Metal can be removed from the crystal lattice during melting, that is, to make the substance of the amorphous structure vitreous. During hardening with artificial cooling, the crystal lattice is again formed. Amorphous metal has simply amazing resistance to corrosion. For example, the car body made of it would not need different coatings, as it would not be subjected to spontaneous destruction. Amorphous substance is a body whose atomic structure possesses unprecedented strength, which means that an amorphous metal could be used in absolutely any industrial branch.

Crystalline structure of substances

To have a good understanding of the characteristics of metals and be able to work with them, one must have knowledge of the crystal structure of certain substances. The production of metal products and the metallurgical industry could not have developed if people did not have a certain knowledge about changes in the structure of alloys, technological methods and performance characteristics.

Four states of matter

It is well known that there are four aggregate states: solid, liquid, gaseous, plasma. Solid amorphous substances can also be crystalline. With such a structure, spatial periodicity in the arrangement of particles can be observed. These particles in crystals can perform periodic motion. In all the bodies that we observe in gaseous or liquid state, one can notice the motion of particles in the form of chaotic disorder. Amorphous solids (for example, metals in a condensed state: ebonite, glass products, resins) can be called frozen liquids, because they have a characteristic feature such as viscosity when changing shape.

The difference between amorphous bodies from gases and liquids

The manifestations of plasticity, elasticity, hardening during deformation are inherent in many bodies. Crystalline and amorphous substances have more of these characteristics, while liquids and gases do not have these properties. But you can see that they contribute to an elastic change in volume.

Crystalline and amorphous substances. Mechanical and physical properties

What are crystalline and amorphous substances? As already mentioned above, those bodies that possess a huge viscosity coefficient can be called amorphous, and at their ordinary temperature their fluidity is impossible. But the high temperature, on the contrary, allows them to be fluid, like a liquid.

Absolutely others are substances of a crystalline type. These solids can have their melting point, depending on the external pressure. The production of crystals is possible if the liquid is cooled. If you do not take certain measures, you can notice that different crystallization centers begin to appear in the liquid state. The region surrounding these centers produces a solid. Very small crystals begin to unite with each other in a disorderly manner, and a so-called polycrystal is produced. Such a body is isotropic.

Characteristics of substances

What determines the physical and mechanical characteristics of bodies? Important are the atomic bonds, as well as the type of crystal structure. Ion-type crystals are characterized by ionic bonds, which means a smooth transition from one atom to another. In this case, positively and negatively charged particles form. We can observe the ionic bond by a simple example - such characteristics are inherent in various oxides and salts. Another feature of ionic crystals is the low conductivity of heat, but its values can increase noticeably when heated. At the nodes of the crystal lattice, it is possible to notice various molecules that are distinguished by a strong atomic bond.

A lot of minerals that we meet everywhere in nature have a crystalline structure. And the amorphous state of matter is also nature in its pure form. Only in this case the body is something formless, but crystals can take the forms of beautiful polyhedra with the presence of flat faces, and also form new surprising beauty and purity solids.

What are crystals? Amorphous-crystalline structure

The shape of such bodies is constant for a certain connection. For example, beryl always looks like a hexagonal prism. Do a little experiment. Take a small crystalline cube-shaped table salt (ball) and put it in a special solution as saturated as possible with the same table salt. Over time, you will notice that this body has remained unchanged - it again took the form of a cube or a ball, which is inherent in crystals of table salt.

Amorphous-crystalline substances are such bodies that can contain both amorphous and crystalline phases. What affects the properties of materials of such a structure? Mainly different volume ratio and different location in relation to each other. Common examples of such substances are materials made of ceramics, porcelain, sitall. From the table of properties of materials with an amorphous-crystalline structure, it is known that porcelain contains the maximum percentage of the glass phase. The indicators fluctuate within 40-60 percent. The lowest content we see on the example of stone casting - less than 5 percent. At the same time, higher water absorption will be at the ceramic tile.

As is known, such industrial materials as porcelain, ceramic tile, stone casting and sital, are amorphous-crystalline substances, because they contain vitreous phases and at the same time crystals in their composition. It should be noted that the properties of the materials do not depend on the content of the glass phases in it.

Amorphous metals

The use of amorphous substances is most actively carried out in the field of medicine. For example, a rapidly cooled metal is actively used in surgery. Thanks to the related developments, many people had the opportunity to move independently after severe injuries. The thing is that the substance of the amorphous structure is an excellent biomaterial for implantation in the bone. Obtained special screws, plates, pins, pins are introduced in severe fractures. Previously, surgery for such purposes used steel and titanium. Only later it was noticed that amorphous substances dissolve very slowly in the body, and this surprising property makes it possible to recover bone tissues. Subsequently, the substance is replaced by a bone.

Application of amorphous substances in metrology and precision mechanics

Precise mechanics is based precisely on accuracy, and therefore it is called. A particularly important role in this industry, as well as in metrology, is the use of ultra-precise indicators of measurement instruments, this allows us to achieve the use of amorphous bodies in devices. Due to precise measurements, laboratory and scientific research is conducted in institutes in the field of mechanics and physics, new preparations are received, scientific knowledge is improved.

Polymers

Another example of the use of amorphous substances is polymers. They can slowly transition from a solid state to a liquid, while crystalline polymers have a melting point and not a softening point. What is the physical state of amorphous polymers? If you give these substances a low temperature, you can see that they will be in a glassy state and exhibit the properties of solids. Gradual heating contributes to the fact that polymers begin to transition to a state of increased elasticity.

Amorphous substances, examples of which we have just given, are intensively used in industry. The superelastic state allows polymers to be deformed arbitrarily, but this state is achieved due to the increased flexibility of the links and molecules. Further increase of the temperature indices leads to the fact that the polymer acquires even more elastic properties. He begins to move into a special fluid and viscous state.

If you leave the situation unchecked and do not prevent further temperature increase, the polymer will undergo destruction, that is, destruction. The viscous state shows that all links of the macromolecule are very mobile. When a polymer molecule flows, the links not only straighten out, but also strongly converge with each other. Intermolecular action converts the polymer into a rigid substance (rubber). This process is called mechanical glass transition. The obtained substance is used for the production of films and fibers.

Based on polymers, polyamides, polyacrylonitriles can be obtained. To make a polymer film, it is necessary to press the polymers through spinnerets that have a slit-like hole and apply to the tape. In this way, packaging materials and bases for magnetic tapes are manufactured. Polymers also include various varnishes (forming a foam in an organic solvent), adhesives and other fastening materials, composites (polymer base with filler), plastics.

Fields of application of polymers

This kind of amorphous substances are firmly established in our lives. They are applied everywhere. They include:

1. Various bases for the manufacture of varnishes, glues, plastic products (phenol-formaldehyde resins).

2. Elastomers or synthetic rubbers.

3. Electrical insulating material - polyvinyl chloride, or all known plastic windows made of PVC. It is resistant to fires, as it is considered to be fire-resistant, has increased mechanical strength and electrical insulation properties.

4. Polyamide - a substance with very high strength, resistance to wear. He has high dielectric characteristics.

5. Plexiglas, or polymethyl methacrylate. We can apply it in the field of electrical engineering or use it as a material for structures.

6. Fluoroplastic, or polytetrafluoroethylene, is a known dielectric that does not exhibit dissolution properties in solvents of organic origin. An extensive temperature range and good dielectric properties allow it to be used as a hydrophobic or antifriction material.

7. Polystyrene. This material is not affected by acids. It, as well as fluoroplastic and polyamide, can be considered a dielectric. Very resistant to mechanical stress. Polystyrene is used universally. For example, it has proven itself as a structural and electrical insulating material. It is used in electrical and radio engineering.

8. Probably the best known polymer for us is polyethylene. The material exhibits stability under the influence of an aggressive environment, it absolutely does not pass moisture. If the packaging is made of polyethylene, you can not be afraid that the contents will deteriorate under the influence of heavy rain. Polyethylene is also a dielectric. Its application is extensive. It produces pipe structures, various electrical products, insulating film, casings for telephone and power line cables, parts for radio and other equipment.

9. Polyvinyl chloride is a highly polymeric substance. It is synthetic and thermoplastic. Has a molecular structure that is asymmetric. Almost does not pass water and is made by pressing by stamping and by molding. Polyvinylchloride is used most often in the electrical industry. It is based on the creation of various heat-insulating hoses and hoses for chemical protection, battery banks, insulating sleeves and gaskets, wires and cables. Polyvinyl chloride is also an excellent substitute for harmful lead. It can not be used as high-frequency circuits in the form of a dielectric. And all because of the fact that in this case the dielectric losses will be high. Has high conductivity.