The main areas of application of artificial crystals. Growing ruby crystals at home Artificial crystal

29.06.2020

Since ancient times, humanity has been using crystals. Initially, these were natural crystals that were used as tools and means for healing and meditation. Later, rare stones and precious metals began to act as cash. Fundamental scientific research and discoveries of the 20th century made it possible to develop methods for obtaining artificial crystals and significantly expand the areas of their application.

A single crystal is a homogeneous crystal that has a continuous crystal lattice and anisotropy of properties. The external form of a single crystal depends on the atomic-crystal structure and crystallization conditions. Examples of single crystals are single crystals of quartz, rock salt, Icelandic spar, diamond, topaz.

If the crystal growth rate is high, polycrystals will be formed, which have a large number of single crystals. Single crystals of high-purity substances have the same properties regardless of the preparation method.

Today, there are about 150 ways to obtain single crystals: vapor phase, liquid phase (solutions and melts) and solid phase.

At the department of high-temperature materials and powder metallurgy, I use the last method to grow single crystals of lanthanum hexaboride and various eutectic alloys based on it. Single crystals of these compounds are used to produce cathodes used in emission technology.

Thanks to the development of electrical engineering and electronics, the use of single crystals is increasing from year to year. Parts made of high-purity monocrystalline materials can be seen in all new models of electronic devices, from radio receivers to large electronic calculating machines.

The technology lacks a set of properties of natural crystals, so scientists have developed a complex technological method of creating crystal-like substances with an intermediate property, by growing ultrathin layers (units to tens of nanometers) of alternating crystals with similar crystal lattices - the epitaxy method. These crystals are called photonic crystals.

In photonic crystals there are forbidden energy bands - these are the values of the energy of photons that cannot penetrate into the crystal and dissolve in it. If the energy of a quantum of light has a permissible value, then it will successfully pass through the crystal. That is, photonic crystals can act as a light filter that allows photons with certain energy values to pass through and filters out all others.

Photonic crystals have 3 groups, which are determined by the number of spatial axes in which the refractive index changes. According to this criterion, crystals are divided into one-, two- and three-dimensional.

A well-known representative of photonic crystals is opal, which has an amazing color pattern, which appears precisely due to the existence of forbidden energy zones.

Single crystals of artificial sapphires are only slightly inferior to the hardness of diamond and have high scratch resistance, which allows them to be used as protective screens in electronic devices (tablets, smartphones, etc.). The application of the Czochralski method makes it possible to obtain huge single crystals of artificial sapphires.

Nowadays, scientists are increasingly talking about nanocrystals. Nanocrystals can have a size from 1 to 10 nm, which depends on the type of nanocrystals, as well as on their preparation method. They are typically 100 nm for ceramics and metals, 50 nm for diamond and graphite, and 10 nm for semiconductors. The size of nanocrystals affects the appearance of unusual properties in familiar substances.

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Fetisov Nikolay

The world around us consists of crystals, we can say that we live in the world of crystals. Residential buildings and industrial structures, airplanes and rockets, motor ships and diesel locomotives, rocks and minerals are composed of crystals. We eat crystals, we heal with them and are partially made of crystals.

So what are crystals? What properties do they have? How do crystals grow? How and where are they currently used and what are the prospects for their use in the future? These questions interested me, and I tried to find answers to them.

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11 SCIENTIFIC AND PRACTICAL CONFERENCE OF THE KUZNETSK DISTRICT "OPEN WORLD"

SECTION OF PHYSICS

The main fields of application of artificial crystals

Completed by a student of grade 8

Fetisov Nikolay

Head A. Sizochenko,

Physics teacher

Municipal general education

Institution

"The main general education

School number 24 "

Novokuznetsk, 2014

Introduction ……………………………………………………… 2

1. Main part

1.1. The concept of a crystal ……………… ... ……… .. …… ..4

1.2. Single crystals and polycrystals ........................ 4

1.3. Crystal growing methods ……… ...….… 5

1.4. Application of crystals ………………… ..… ...… 7

2. Practical part

2.1. Growing crystals at home

Conditions ……………………………………… ... 9

3. Conclusion …………………………………………….… 11

Bibliography .. ……………………………………………… ... 13

Appendices …………………………. …………………… ..14-15

Introduction

Like a magic sculptor

Light crystal facets

Sculpts a colorless solution.

N.A. Morozov

Crystals are substances in which the smallest particles are “packed” in a specific order. As a result, during the growth of crystals, flat faces spontaneously appear on their surface, and the crystals themselves take on a variety of geometric shapes.

Statement by Academician A.E. Fersman “Almost the whole world is crystalline. The crystal reigns in the world and its rigid rectilinear laws ”is consistent with the scientific interest of scientists all over the world in this object of research.

Modern industry cannot do without a wide variety of crystals. They are used in watches, transistor receivers, computers, lasers, and more. The great laboratory - nature - can no longer satisfy the demand of developing technology, and now artificial crystals are grown in special factories: small, almost imperceptible, and large - weighing several kilograms.

People have learned to artificially obtain a lot of precious stones. For example, bearings for watches and other precision instruments have long been made of artificial rubies. Artificially obtained and beautiful crystals that do not exist in nature at all - cubic zirconia. Cubic zirconias by eye are difficult to distinguish from diamonds - they play so beautifully in the light.

My work is research work, as in its implementation, knowledge of several academic subjects is used: physics, chemistry, biology, computer science. As a result of my activity, I created a presentation "Crystals and Their Applications", which can be used in physics and chemistry lessons as a visual aid, and grown crystals from copper sulfate and sodium chloride.

Target:

Determine the main areas of application of artificial crystals and test empirically the possibility of growing crystals of sodium chloride and copper sulfate without the use of special equipment.

To achieve this goal, the following stood before me

tasks:

Collect material about crystals and their properties from literary and Internet sources.
Conduct experiments on growing crystals of copper sulfate and sodium chloride.
To systematize the material about crystals: the use of artificial crystals and methods of growing them.
Create a presentation "Crystals and Their Applications" for educational purposes.

Main part

Crystal concept

Crystal (from the Greek. krystallos - "transparent ice") in the beginning they called transparent quartz (rock crystal), which was found in the Alps. Rock crystal was taken for ice, hardened from the cold to such an extent that it no longer melts. Initially, the main feature of the crystal was seen in its transparency, and this word was used in application to all transparent natural solids. Later, they began to produce glass, which was not inferior in brilliance and transparency to natural substances. Items made of such glass were also called "crystal". Even today, glass of special transparency is called crystal, the "magic" ball of fortune-tellers is called a crystal ball.

A surprising feature of rock crystal and many other transparent minerals is their smooth, flat edges. At the end of the 17th century. it was noticed that there is a certain symmetry in their arrangement and it was found that some opaque minerals have a natural regular cut. There was a hunch that the shape could be related to the internal structure. In the end, crystals began to be called all solids that have a natural flat cut.

In the armory there are clothes and crowns of Russian tsars, all covered with crystals - gems - amethysts. In churches, icons and altars were decorated with amethysts.

The most famous crystals are diamonds, which, after cutting, turn into diamonds. People have tried to unravel the mystery of these stones for many centuries, and when it was established that a diamond is a kind of carbon, no one believed it.

The decisive experiment was carried out in 1772 by the French chemist Lavoisier. In nature, diamonds are formed in the bowels of the earth at very high temperatures and pressures. Scientists were able to create conditions in the laboratory under which diamond can be obtained from graphite only 200 years later. Tens of tons of artificial diamonds are now being produced. Among them there are diamonds for jewelry purposes, but most of them are used to make various tools.

Monocrystals and polycrystals

Crystalline bodies can be monocrystals and polycrystals. A single crystal is a single crystal that has a macroscopic ordered crystal lattice. They have a geometrically correct external shape, but this feature is optional.

Polycrystals are chaotically oriented small crystals intergrown with each other - crystallites.

Crystal growing methods

In the laboratory, crystals are grown under carefully controlled conditions that provide the desired properties, but in principle, laboratory crystals are formed in the same way as in nature - from solution, melt or vapor. Thus, piezoelectric crystals of Rochelle salt are grown from an aqueous solution at atmospheric pressure. Large crystals of optical quartz are also grown from solution, but at temperatures of 350-450 O C and a pressure of 140 MPa. Rubies are synthesized at atmospheric pressure from aluminum oxide powder melted at a temperature of 2050 O C. Crystals of silicon carbide used as an abrasive are obtained from fumes in an electric furnace.

The first single crystal obtained in the laboratory was ruby. To obtain ruby, a mixture of anhydrous alumina containing a greater or lesser amount of caustic potassium with barium fluoride and two-chromium salt was heated. The latter is added in order to cause the color of the ruby, and alumina is taken in a small amount. The mixture is placed in a clay crucible and heated (from 100 hours to 8 days) in reflective furnaces at temperatures up to 1500 O C. At the end of the experiment, a crystalline mass appears in the crucible, and the walls are covered with crystals of a beautiful pink ruby.

The second common method of growing synthetic gem crystals is the Czochralski method. It consists in the following: the melt of the substance from which the stones are supposed to crystallize is placed in a refractory crucible made of a refractory metal (platinum, rhodium, iridium, molybdenum, or tungsten) and heated in a high-frequency inductor. A seed made of the material of the future crystal is lowered into the melt on a pull-out roller, and a synthetic material is built up on it to the required thickness. The shaft with the seed is gradually pulled upward at a speed of 1-50 mm / h with simultaneous growth at a rotational speed of 30-150 rpm. Rotate the shaft to equalize the melt temperature and ensure an even distribution of impurities. The diameter of the crystals is up to 50 mm, the length is up to 1 m. Synthetic corundum, spinel, garnets and other artificial stones are grown by the Czochralski method.

Crystals can also grow during condensation of vapors - this is how snowflake patterns are obtained on cold glass. When metals are displaced from salt solutions with the help of more active metals, crystals are also formed. For example, dip an iron nail into a solution of copper sulfate, it will be covered with a red layer of copper. But the formed copper crystals are so small that they can only be seen under a microscope. On the surface of the nail, copper is released very quickly, so its crystals are too small. But if you slow down the process, the crystals will turn out to be large. For this, copper sulfate must be covered with a thick layer of table salt, put a circle of filter paper on it, and on top - an iron plate with a slightly smaller diameter. It remains to pour a saturated solution of sodium chloride into the vessel. Copper sulfate will slowly dissolve in the brine. Copper ions (in the form of green complex anions) will diffuse upward very slowly over many days; the process can be observed by the movement of the colored border. Having reached the iron plate, copper ions are reduced to neutral atoms. But since this process is very slow, copper atoms line up in beautiful shiny crystals. Sometimes these crystals form branches - dendrites.

The use of crystals.

Natural crystals have always piqued people's curiosity. Their color, brilliance and shape affected the human sense of beauty, and people decorated themselves and their homes with them. Superstition has long been associated with crystals; as amulets, they were supposed not only to protect their owners from evil spirits, but also to endow them with supernatural powers. Later, when the same minerals began to be cut and polished like precious stones, many superstitions were preserved in the talismans "for good luck" and "their stones" corresponding to the month of birth. All natural gemstones, except opal, are crystalline, and many of them, such as diamond, ruby, sapphire and emerald, come across as beautifully cut crystals.Crystal jewelryare as popular now as they were during the Neolithic.

Based on the laws of optics, scientists were looking for a transparent, colorless and defect-free mineral from which lenses could be made by grinding and polishing. Crystals of uncolored quartz possess the required optical and mechanical properties, andfirst lenses, including glasses, were made from them. Even after the advent of artificial optical glass, the need for crystals has not completely disappeared; crystals of quartz, calcite and other transparent substances that transmit ultraviolet and infrared radiation are still used for the manufacture of prisms and lenses of optical devices.

Crystals played an important role in many technical innovations of the 20th century. Some crystals generate an electrical charge when they are deformed. Their first significant application wasmanufacture of radio frequency generators with quartz crystal stabilization.By making the quartz plate vibrate in the electric field of the radio-frequency oscillating circuit, it is possible thereby to stabilize the receiving or transmitting frequency.

Semiconductor diodes are used in computers and communications systems, transistors have replaced vacuum tubes in radio engineering, and solar panels placed on the outer surface of spacecraft convert solar energy into electrical energy. Semiconductors are also widely used in AC-to-DC converters.

Crystals with piezoelectric properties are used in radios and radio transmitters, in pickup heads and in sonars. Some crystals modulate the light beams, while others generate light when a voltage is applied. The list of crystal uses is long and growing.

Artificial crystals.For a long time, man dreamed of synthesizing stones as precious as those found in natural conditions. Until the twentieth century. such attempts were unsuccessful. But in 1902managed to get rubies and sapphireswith the properties of natural stones. Later, in the late 1940s, there weresynthesized emeralds, and in 1955 the General Electric company and the Physics Institute of the USSR Academy of Sciences announced the manufactureartificial diamonds.

It is fully consistent with the unquenchable scientific interest of scientists from all over the world and all fields of knowledge to this object of research. At the end of the 60s of the last century, a serious scientific breakthrough began in the fieldliquid crystals, which gave rise to the "indicator revolution" to replace the switch mechanisms with the means of visual display of information. Later, the concept of a biological crystal (DNA, viruses, etc.) entered science, and in the 80s of the twentieth century - a photonic crystal.

Practical part

Growing crystals at home

Growing crystals is a very interesting process, but rather lengthy and painstaking.

It is useful to know what processes are driving its growth; why different substances form crystals of different shapes, and some do not form them at all; what needs to be done to make them big and beautiful.

I tried to find answers to these questions in my work.

If crystallization proceeds very slowly, one large crystal (or single crystal) is obtained, if quickly, then many small ones.

I have grown crystals at home in different ways.

Method 1 ... Cooling of a saturated solution of copper sulfate. With a decrease in temperature, the solubility of substances decreases, and they precipitate. First, tiny nucleated crystals appear in the solution and on the walls of the vessel. When the cooling is slow, and there are no solid impurities in the solution, many nuclei are formed, and gradually they turn into beautiful crystals of the regular shape. With rapid cooling, many small crystals appear, almost none of them has the correct shape, because many of them grow, and they interfere with each other.

In order to grow a crystal from copper sulfate, I made a supersaturated solution:

1. To do this, I took warm water, dissolved vitriol in it and poured it in until it stopped dissolving.

2. I poured it through a filter (gauze) into another clean container. I poured boiling water over the container in order to prevent the rapid crystallization of the solution on the dirty walls.

3. Prepared the seed.

4. Tied it to a thread, dipped it into the solution.

In order for the crystal to grow evenly on all sides, it is better to keep the seed (small crystal) in a suspended state in the solution. For this, I made a jumper from a glass rod. By the way, it is advisable to take a thread that is smooth, thin, or silk, so that unnecessary small crystals do not form on it. Then I put my solution in a warm place. Slow cooling is very important (in order to obtain a large crystal). Crystallization can be seen in a few hours. Periodically, you need to change or update the saturated solution, as well as clean off small crystals from the thread. (Annex 1)

Method 2 - gradual removal of water from a saturated solution.

In this case, the slower the water is removed, the better the result will be. I left open the jar with a solution of table salt (table salt) at room temperature for 14 days, covering it with a sheet of paper - the water evaporated slowly, and the dust did not get into the solution. The growing crystal was suspended in a saturated solution on a thin strong thread. The crystal turned out to be large, but shapeless - amorphous. (Annex 1)

Growing crystals is an entertaining process, but it requires a careful and careful attitude to your work. In theory, the size of a crystal that can be grown at home in this way is unlimited. There are cases when enthusiasts received crystals of such a size that they could only be lifted with the help of comrades.

But, unfortunately, there are some peculiarities of their storage. For example, if a crystal of alum is left open in dry air, it gradually loses the water it contains and turns into a nondescript gray powder. To protect it from destruction, you can cover it with a colorless varnish. Copper sulfate and table salt are more resistant and you can safely work with them.

Last year, in the 7th grade, at a chemistry lesson, while studying the topic "Phenomena Happening to Substances," we grew crystals, many of them did not succeed. This year, I suggested to the children from the 7th grade how to cope with this task correctly, and this is what they did (see Appendix 2).

Conclusion

All the physical properties due to which crystals are so widely used depend on their structure - their spatial lattice.

Along with solid-state crystals, liquid crystals are now widely used, and in the near future we will use devices based on photonic crystals.

I have selected the most acceptable method for growing crystals at home and grown crystals of salt and copper sulfate. As the crystals grew, he made observations, recorded changes.

Crystals are beautiful, one might say some kind of miracle, they attract to themselves; say the same "man of a crystal soul" about who has a pure soul. Crystal means shining with light, like a diamond. And, if we talk about crystals with a philosophical attitude, then we can say that this is a material that is an intermediate link between living and inanimate matter. Crystals can be born, aged, destroyed. A crystal, when it grows on a seed (on an embryo), inherits the defects of this very embryo. But speaking quite seriously, now, perhaps, it is impossible to name any discipline, not a single area of science and technology, which would do without crystals. Physicians are interested in the environments in which crystallization of kidney stones occurs, and pharmacists in tablets are compressed crystals. Assimilation, dissolution of tablets depends on which faces these microcrystals are coated with. Vitamins, the myelin sheath of nerves, proteins, and viruses are all crystals.

The crystal is miraculous in its properties; it performs a variety of functions. These properties are inherent in its structure, which has a lattice three-dimensional structure. Crystallography is not a new science. M.V. Lomonosov stands at its origins. The growth of crystals became possible thanks to the study of mineralogy data on crystal formation in natural conditions. Studying the nature of crystals, the composition from which they grew and the conditions for their growth were determined. And now these processes are imitated, obtaining crystals with desired properties. Chemists and physicists are involved in the production of crystals. While the former develop technology for growth, the latter determine their properties. Can artificial crystals be distinguished from natural crystals? For example, artificial diamond is still inferior to natural diamond in quality, including brilliance. Artificial diamonds do not cause jewelry joy, but they are quite suitable for use in technology, in this sense they are on an equal footing with natural ones. Again, the impudent growers (as chemists who grow artificial crystals are called) have learned to grow the finest crystal needles with extremely high strength. This is achieved by manipulating the chemistry of the medium, temperature, pressure, and the effect of some other additional conditions. And this is already a whole art, creativity, skill - the exact sciences will not help here.

The topic "Crystals" is relevant, and if you delve into it and delve deeper into it, then it will be interesting to everyone, will give answers to many questions, and most importantly - the unlimited use of crystals. Crystals are mysterious in nature and so extraordinary that in my work I have told only a small part of what is known about crystals and their use at the present time. It may be that the crystalline state of matter is the step that united the inorganic world with the world of living matter. The future of the latest technology belongs to crystals and crystalline aggregates!

Based on my research, I came to the following conclusions:

Artificially grown crystals are used in various fields: medicine, radio engineering, aircraft construction, optics and many others.
The term for obtaining artificial crystals is much shorter than the process of their natural formation. Which makes them more accessible to use.
At home, crystals can be grown even in a short time.

Bibliography

Chemistry. Introductory course. Grade 7: textbook. Manual / O.S. Gabrielyan, I. G. Ostroumov, A.K. Akhlebinin. - 6th ed., M .: Bustard, 2011.
Chemistry. Grade 7: workbook for the textbook O.S. Gabrielyan et al. “Chemistry. Introductory course. Grade 7 "/ O.S. Gabrielyan, G.A. Shipareva. - 3rd ed., - M .: Bustard, 2011.
Landau L.D., Kitaygorodsky A.I. Physics for all, Book 2. Molecules.- M., 1978.
Encyclopedic Dictionary of a Young Chemist. / Comp. V.A. Kritsman, V.V. Stanzo.-M., 1982.
Encyclopedia for children. Volume 4. Geology. / Comp. S.T. Ismailova.-M., 1995.
Internet resources:

http://www.krugosvet.ru - Encyclopedia Around the World.

http://ru.wikipedia.org/ - Wikipedia encyclopedia.

http://www.kristallikov.net/page6.html - how to grow a crystal.

Annex 1.

Observation diary

date	Observations		Photo
date	Salt	Copper sulfate	Salt	Copper Cuparos
24.01.14.	Before lowering the seed into the solution. length: 5mm width: 5mm	We make a loop of wire, hang it up and lower it into the solution.
27.01.14.	length: 11mm width: 7mm	length: 12mm width: 10mm
30.01.14.	length: 20mm width: 10mm	length: 18mm width: 13mm
3.02.14.	Crystal formation has gone beyond the solution boundary	length: 25mm width: 15mm
6.02.14.	The crystal turned out to be large, but shapeless	length: 30mm width: 20mm

Appendix 2

Crystals grown by seventh graders

Slide captions:

Application of crystals
Decorations
Lenses
Prepared seed

Target
: to determine the main areas of application of artificial crystals and to test empirically the possibility of growing crystals of sodium chloride and copper sulfate without the use of special equipment.
Tasks:

Collect material about crystals and their properties.
Conduct experiments on growing crystals of copper sulfate and sodium chloride.
Systematize material about crystals: physical properties of crystals and their applications.
Create a presentation "Crystals and Their Applications".
2. Displacement of metals from salt solutions with the help of more active metals.
Passed the solution through the filter
Thank you for the attention
The main fields of application of artificial crystals
Completed by a student of grade 8
Fetisov Nikolay
Supervisor
Sizochenko
A.I. ,
Physics teacher
Municipal general education
Institution
"The main general education
School number 24 "
Novokuznetsk, 2014
conclusions
Artificially grown crystals are used in various fields: medicine, radio engineering,
aircraft-machine
structure, optics and many others.
The term for obtaining artificial crystals is much shorter than the process of their natural formation. Which makes them more accessible to use.
At home, crystals can be grown even in a short time.
Crystal growing methods
Method
Czochralski
- crucible
method:
melt
substance from which
supposed to crystallize
stones placed in a fireproof
crucible
refractory metal (platinum, rhodium,
iridium
, molybdenum, or tungsten) and heated in
high frequency
inductor.
(Gems: rubies)
Clay crucible
Growing crystals at home
Method 1
: Slow cooling of saturated solution
Preparing a supersaturated solution
Polycrystals
Monocrystals
Crystals grown by seventh graders
Liquid crystals
Crystals
are solid
substances,

having a natural
external shape
regular symmetric polyhedra
founded
on
their internal
structure
Semiconductor diodes, transistors, solar cells
Method 2:
Gradual removal of water from a saturated solution

V
In this case, the slower the water is removed, the better the result will be.

Need to leave the vessel
with cooking solution
salt,
covering it with a sheet of paper - water while
evaporates
slowly, and the dust into the solution does not
falls.

Crystal
it turned out to be large, but shapeless - amorphous.

Artificial crystals

For a long time, man dreamed of synthesizing stones as precious as those found in natural conditions. Until the XX century. such attempts were unsuccessful. But in 1902, rubies and sapphires were obtained, which have the properties of natural stones. Later, in the 1940s, emeralds were synthesized, and in 1955 the General Electric Company and the Physics Institute of the USSR Academy of Sciences announced the production of artificial diamonds.

Many technological needs for crystals have stimulated research into methods for growing crystals with predetermined chemical, physical, and electrical properties. The works of the researchers were not in vain, and methods were found to grow large crystals of hundreds of substances, many of which have no natural analogue. In the laboratory, crystals are grown under carefully controlled conditions that provide the desired properties, but in principle, laboratory crystals are formed in the same way as in nature - from solution, melt or vapor. Thus, piezoelectric crystals of Rochelle salt are grown from an aqueous solution at atmospheric pressure. Large crystals of optical quartz are also grown from solution, but at temperatures of 350-450 ° C and a pressure of 140 MPa. Rubies are synthesized at atmospheric pressure from powder of aluminum oxide, melted at a temperature of 2050 o C. Crystals of silicon carbide, used as an abrasive, are obtained from vapors in an electric furnace.

The use of liquid crystals in devices

information display

At that time, the existence of liquid crystals seemed like some kind of curiosity, and no one could have imagined that a great future in technical applications awaited them in almost a hundred years. Therefore, after some interest in liquid crystals immediately after their discovery, after a while they were practically forgotten.

In the late nineteenth and early twentieth centuries, many highly respected scientists were very skeptical about the discovery of Reinitzer and Lehmann. The fact is that not only the described contradictory properties of liquid crystals seemed to many authorities to be very doubtful, but also that the properties of various liquid crystal substances turned out to be significantly different. Some liquid crystals had very high viscosity, while others had low viscosity. As time went on, the facts about liquid crystals gradually accumulated, but there was no general principle that would allow establishing any system in terms of liquid crystals. The merit in creating the foundations of the modern classification of liquid crystals belongs to the French scientist J. Friedel. In the 1920s, Friedel proposed to divide all liquid crystals into two large groups. He called one group nematic, the other smectic. He also proposed a general term for liquid crystals (mesomorphic phase). Friedel wanted to emphasize that liquid crystals occupy an intermediate position between true crystals and liquids, both in temperature and in their physical properties. The nematic liquid crystals in Friedel's classification included the already mentioned cholesteric liquid crystals as a class. The most "crystalline" among liquid crystals are smecatic. Two-dimensional ordering is characteristic of smecatic crystals. The molecules are placed so that their axes are parallel. Moreover, they “understand” the command “equal” and are placed in orderly rows packed on smecatic planes, and in rows on nematic ones.

Application

The arrangement of molecules in liquid crystals changes under the influence of such factors as temperature, pressure, electric magnetic fields; changes in the arrangement of molecules lead to a change in optical properties, such as color, transparency, and the ability to rotate the plane of polarization of the transmitted light. Numerous applications of liquid crystals are based on this. For example, color versus temperature is used in medical diagnostics. By applying some liquid crystal materials to the patient's body, the physician can easily identify affected tissues by discoloration in areas where these tissues generate increased amounts of heat. The temperature dependence of color also allows you to control the quality of products without destroying them. If a metal product is heated, then its internal defect will change the temperature distribution on the surface. These defects are detected by the color change applied to the surface of the liquid crystal material. Liquid crystals are widely used in the manufacture of wristwatches and calculators. Flat-panel televisions with a thin liquid crystal screen are being created. Relatively recently, a carbon and polymer fiber based on liquid crystal matrices has been obtained.

Future liquid crystal applications

Guided optical transparencies. It is known that the mass creation of large flat screens based on liquid crystals encounters difficulties of an unprincipled and technological nature. Although in principle the possibility of creating such screens has been demonstrated, however, due to the complexity of their production with modern technology, their cost turns out to be very high. Therefore, the idea arose of creating projection devices based on liquid crystals, in which the image obtained on a small-size liquid crystal screen could be projected in an enlarged form onto a conventional screen, similar to what happens in a movie theater with film frames. It turned out that such devices can be realized on liquid crystals by using sandwich structures, which include a photosemiconductor layer with a liquid crystal layer. The recording of an image in a liquid crystal, carried out with the help of a photosemiconductor, is performed by a light beam. The principle of image recording is very simple. In the absence of illumination of a photosemiconductor, its conductivity is very low; therefore, practically the entire potential difference applied to the electrodes of the optical cell, into which a photosemiconductor layer is additionally introduced, falls on this photosemiconductor layer. In this case, the state of the liquid crystal layer corresponds to no voltage on it. When the photosemiconductor is illuminated, its conductivity increases sharply, since the light creates additional current carriers (free electrons and holes) in it. As a result, there is a redistribution of electrical voltages in the cell - now almost all voltage drops across the liquid crystal layer, and the state of the layer, in particular, its optical characteristics, change according to the magnitude of the applied voltage. Thus, the optical characteristics of the liquid crystal layer are changed as a result of the action of the layer.

Glasses for astronauts

Getting acquainted with a mask for an electric welder and glasses for stereo television, we noticed that in these devices a controllable liquid crystal filter covers the entire field of view of one or both eyes at once. There is a situation when it is impossible to overlap the entire field of view of a person and at the same time it is necessary to overlap individual sections of the field of view.

For example, such a need may arise for astronauts in the conditions of their work in space under extremely bright sunlight. Controlled liquid crystal filters can solve this problem, as in the case of a mask for an electric welder or glasses for stereo television. In these glasses, the field of view of each eye must now be covered not by one filter, but by several independently controlled filters. For example, the filters can be made in the form of concentric rings centered in the center of the glasses or in the form of stripes on the glasses, each of which, when turned on, blocks only part of the eye's vision.

Such glasses can be useful not only for astronauts, but also for people of other professions, for example, for pilots of modern aircraft, where there is a huge amount of instruments. Such glasses will also be very useful in biomedical studies of the operator's work associated with the perception of a large amount of visual information.

Filters of this type and liquid crystal indicators will undoubtedly find (and are already finding) wide application in cinema and photographic equipment. For these purposes, they are attractive in that they require an insignificant amount of energy to control them, and in a number of cases they make it possible to exclude parts from the equipment; performing mechanical movements. What mechanical parts of cinema and photographic equipment are meant? These are diaphragms, filters - light flux attenuators, and finally, light flux interrupters in a filming camera, synchronized with the movement of the photographic film and ensuring its frame-by-frame exposure.

Photonic crystals- one of the objects of nanotechnology, an interdisciplinary field that serves as the basis for technology in the XXI century. in all areas of human activity (informatics, medicine, metal technology, etc.). The term "photonic crystal" appeared in the 80s of the XX century.

Over the past 10 years, there has been an increased interest in photonic crystals and devices based on them both from physicists and from leading high-tech enterprises and enterprises of the military-industrial complex. The situation is compared with the period of rapid development in the 1960s of integrated microelectronics, and it is determined by the possibility of creating optical microcircuits by analogy with the circuits of classical microelectronics. The possibility of fundamentally new methods of storing, transferring and processing information on the basis of materials of a new type (photonics) has opened up. It is planned to create lasers of a new type, with a low lasing threshold, and optical switches. However, the creation of three-dimensional photonic crystals (namely, they should lead to fundamental changes in technology) is a rather difficult task.

Photonic crystals have opened up an amazing opportunity for storing and processing information - creating photon traps. This is a region in the crystal from which the escape of photons is prohibited due to the absence of a photonic conduction band in the surrounding material. The situation is compared to a charged conductor surrounded by a dielectric. The paradoxical situation of "stopping a photon", whose mass is equal to zero, does not contradict the laws of physics, since we are not talking about a free photon interacting with a periodic structure. It has already been dubbed a heavy photon. Heavy photons are planned to be used in memory elements, optical transistors, etc.

The second, already real in the near future, area of application of photonic crystals is to increase the efficiency of incandescent lamps by an order of magnitude. In the future, it is planned to switch to computers based solely on photonics, which have a number of advantages over computers based on electronics.

In 2004, a message appeared about the creation of a laser based on artificial inverted opal. Colloidal particles of cadmium selenide with a diameter of 4.5 nm were introduced into hollow spheres located at a distance of 240-650 mm. With the help of a laser pulse, these "artificial atoms" were transferred to an excited state, and the emission time could be controlled. Note that it is advantageous to use lasers with an emission delay, for example, for solar cells, and with accelerated emission - for mini-lasers and light-emitting diodes.

The origin and structure of precious stones

All precious stones, with rare exceptions, belong to the world of minerals. Let us recall their origin and structure. On the conditions for the formation of precious stones that are not minerals in the strict sense of the word (for example, amber, coral and pearls).

Minerals can arise in a variety of ways. Some are formed from fiery liquid melts and gases in the bowels of the Earth or from volcanic lavas erupted onto its surface (magmatic minerals). Others fall out of aqueous solutions or grow with the help of organisms on (or near) the earth's surface (sedimentary minerals). Finally, new minerals are formed by recrystallization of existing minerals under the influence of high pressures and high temperatures in the deep layers of the earth's crust (metamorphic minerals).

The chemical composition of minerals is expressed by the formula. In this case, impurities are not taken into account, even if they cause the appearance of color shades, up to a complete change in the color of the mineral. Almost all minerals crystallize in certain forms. That is, they are crystals of uniform body composition with a regular arrangement of atoms in the lattice. Crystals are characterized by strict geometric shapes and are limited mainly by smooth flat faces. Most of the crystals are small, but there are giant specimens. The internal structure of crystals determines their physical properties, including external shape, hardness and fracture ability, fracture type, density, and optical phenomena.

Basic concepts

Gem or gem. All this group of stones is distinguished by one common feature - special beauty. Before, only a few stones were called gems. Today their number has increased dramatically and continues to increase. Most of them are minerals, much less often - rocks. Certain minerals of organic origin are also referred to as precious stones: amber, coral and pearls. Even fossil organic remains (fossils) are used as decorations. By their purpose, a number of other jewelry materials are close to precious stones: wood, bone, glass and metal.

Semiprecious stone - the concept still prevails in trade, but, however, in view of the derogatory meaning inherent in it, it should not be used. Previously, less valuable and not very hard stones were called semiprecious, contrasting them with "real" precious stones.

Ornamental stone. This is a collective term that refers to all stones used both as decoration and for the production of stone-cutting products. Sometimes less valuable or opaque stones are called ornamental.

Jewel. A piece of jewelry is understood as an adornment consisting of one or more precious stones set in a noble metal. Sometimes polished stones without rims, as well as jewelry made of precious metals without stones, are also called jewelry.

Gems and semi-precious stones

Gems have been known to man for more than seven millennia. The first of these were: amethyst, rock crystal, amber, jade, coral, lapis lazuli, pearls, serpentine, emerald and turquoise. For a long time these stones remained available only to representatives of the privileged classes and not only served as decoration, but also symbolized the social status of their owners.

Until the beginning of the 19th century. precious stones were even used for medicinal purposes. In some cases, it was considered sufficient to have a certain stone, and in others, it was applied to the sore spot, in the third, it was pounded into powder and taken orally. Ancient medical books contain "exact" information about which stone can help in a particular disease. Treatment with precious stones is called lithotherapy. Sometimes it brought success, but it should not be attributed to the stone itself, but to a psychological suggestion that had a beneficial effect on the patient. Failures in treatment were explained by the fact that the stone turned out to be “fake”. In Japan, tablets made from powdered pearls (that is, from calcium carbonate) are sold for medicinal purposes today.

And in modern religions, precious stones have a separate place. Thus, the breastplate of the Jewish high priest is adorned with four rows of precious stones. Similar stones sparkle on the tiaras and mitres of the pope and bishops of the Christian church, as well as on arks, monstrous bearers, crayfish and icon frames.

Cleavage and fracture

Many minerals split or disintegrate along flat, flat surfaces. This property of minerals is called cleavage and depends on the structure of their crystal lattice, on the forces of cohesion between atoms. Distinguish between very perfect cleavage (euclase), perfect (topaz) and imperfect (garnet). A number of precious and ornamental stones (for example, quartz) do not have it at all. Separately called the ability of a crystal to crack in certain areas along parallel oriented surfaces.

The presence of cleavage must be taken into account when grinding and cutting stones, as well as when inserting them into the frame. Strong mechanical stress can cause a split (crack) along cleavage. Often a light blow or excessive pressure when determining the hardness is sufficient for this. Previously, cleavage was used to neatly dissect large stones into pieces or to separate defective areas. These operations are now performed primarily by sawing, which allows better use of the shape of the stone, as well as avoiding unwanted cracks and splits.

The shape of the surface of the fragments into which the mineral disintegrates upon impact is called kink. It can be conchoidal (similar to a shell imprint), uneven, splintered, fibrous, stepped, even, earthy, etc. Sometimes a fracture can serve as a diagnostic sign that makes it possible to distinguish minerals with similar external appearance. A crusty fracture is typical, for example, of all types of quartz and for imitation of glass gemstones.

Density

Density (before it was called specific gravity) is the ratio of the mass of a substance to the mass of the same volume of water. Consequently, a stone with a density of 2.6 is as many times heavier than an equal volume of water.

The density of precious stones ranges from 1 to 7. Stones with a density below 2 seem to us light (amber 1.1), from 2 to 4 - of normal weight (quartz 2.65), and above 5 - heavy (cassiterite 7.0). The most expensive stones, such as diamond, ruby, sapphire, have a higher density than the main rock-forming minerals, primarily quartz and feldspar.

Measures of the mass of gemstones

Carat - a unit of mass that has been used in the gem trade and jewelry since ancient times. It is possible that the word "carat" itself comes from the local name (kuara) of the African coral tree, the seeds of which were used to weigh the golden sand, but it is more likely that it originates from the Greek name (keration) of the widespread Mediterranean carob tree, fruits which originally served as "weights" when weighing precious stones (the mass of one weight is on average approximately equal to a carat).

Gram - unit of mass used in the gemstone trade for less expensive stones, and especially for raw gemstones (such as a group of quartz)

Grand - a measure of the mass of a pearl. Corresponds to 0.05 g, i.e. 0.25 ct. Now the grain is more and more superseded by karat.

Price. In the gem trade, the price is usually quoted per carat. To calculate the total cost of a stone, multiply the price and its carat weight.

Optical properties

Among the physical properties of precious stones, optical properties play a dominant role; determining their color and brilliance, sparkle, "fire" and luminescence, asterism, iridescence and other light effects. When testing and identifying gemstones, more and more attention is paid to optical phenomena.

Colour

Colour- the first thing that catches the eye when looking at any precious stone. However, for most stones, their color cannot serve as a diagnostic feature, since many of them are colored the same way, and some appear in several colors.

The reason for the different colors is light, that is, electromagnetic oscillations that lie in a certain wavelength interval. The human eye perceives only waves of the so-called optical range - from about 400 to 700 nm. This area of visible light is subdivided into seven main parts, each of which corresponds to a specific color of the spectrum: red, orange, yellow, green, blue, blue, violet. When all spectral colors are mixed, a white color is obtained. If, however, a range of wavelengths is absorbed, a certain - no longer white - color arises from the mixture of the remaining colors. A stone that transmits all wavelengths of the optical range appears colorless; if, on the contrary, all the light is absorbed, then the stone acquires the darkest of the visible colors - black. With partial absorption of light over the entire wavelength range, the stone looks dull white or gray. But if, on the contrary, only completely certain wavelengths are absorbed, then the stone acquires a color corresponding to the mixing of the remaining unabsorbed parts of the white light spectrum. The main carriers of color - chromophores that determine the color of precious stones - are heavy metal ions of iron, cobalt, nickel, manganese, copper, chromium, vanadium and titanium.

The color of gemstones also depends on the lighting, since the spectra of artificial (electric) and daytime (sunlight) light are different. There are stones on the color of which artificial light has an adverse effect (sapphire), and those that, in the evening (artificial) light, only benefit by increasing their radiance (ruby, emerald). But the color change is most pronounced in alexandrite: during the day it looks green, and in the evening it looks red.

Refraction

Even as a child, we have seen more than once that a stick is not completely submerged in water at an acute angle, as if it “breaks” at the water surface. The lower part of the stick in the water takes on a different slope than the upper part in the air. This is due to the refraction of light, which is always manifested when a light beam passes from one medium to another, that is, at the border of two substances, if the beam is directed obliquely to the interface between them.

The amount of light refraction of all crystals of precious stones of the same mineral type is constant (sometimes it fluctuates, but within a very narrow interval). Therefore, the numerical expression of this quantity - the refractive index (often referred to simply as refraction or light refraction) - is used to diagnose gemstones. Refractive index is defined as the ratio of the speeds of light in air and in a crystal. The point is that the deflection of a light beam in a crystal is caused precisely by a decrease in the propagation velocity of this beam in an optically denser medium.

In a diamond, light travels 2.4 times slower than in air. Without great technical difficulties and costs, it is possible to measure light refraction by the immersion method - by immersing the stone in liquids with a known refractive index and observing the interface. By how light and sharp the contours of the stone or the edges between the facets appear, as well as by the apparent width of the interfaces, one can fairly accurately estimate the refractive index of a gemstone.

Dispersion

When passing through a crystal, white light not only undergoes refraction, but also decomposes into spectral colors, since the refractive indices of crystalline substances depend on the wavelength of the incident light. The phenomenon of the decomposition of white light by a crystal into all colors of the rainbow is called variance. Especially great is the value of color dispersion in diamond, which owes it to her for its magnificent play of colors - the famous "fire" that is the main charm of this stone.

Dispersion is good only for colorless stones. Natural and synthetic stones with high dispersion (for example, fabulite, rutile, spharlerite, titanite, zircon) are used in jewelry as a substitute for diamond.

Surface optical effects:

light figures and color overflows

Many gemstones have light figures in the form of oriented stripes of light, as well as color overflows of the surface.

Cat's eye effect inherent in stones that are aggregates of parallel accrete fibrous or needle-like individuals or containing thin parallel-oriented hollow channels. The effect arises due to the reflection of light on such parallel intergrowths and consists in the fact that when the stone is turned, a narrow light strip runs over it, recalling the luminous slit pupil of the cat. The greatest impression of this effect is achieved if the stone is polished in the form of a cabochon, moreover, so that the flat base of the cabochon is parallel to the fibrous structure of the stone.

Asterism - the appearance on the surface of the stone of light figures in the form of light stripes intersecting at one point and resembling star rays; the number of these rays and the angle of their intersection are determined by the symmetry of the crystals. By its nature, it is similar to the effect of a cat's eye with the only difference that reflective inclusions - thin fibers, needles or tubules - have different orientations in different areas. The six-pointed stars on the ruby and sapphire cabochons are very impressive.

Adularisation - the bluish-white shimmer of moonstone, a precious variety of adularia. When the moonstone cabochon is moved, this radiance, or ebb, glides over its surface.

Irisation - iridescent color play of some gem stones, the result of the decomposition of the white color refracted on small breaks and cracks in the stone into spectral colors.

"Silk" - silky shine and play of some gemstones caused by the presence of parallel-oriented inclusions of fine-fiber or needle-like minerals or hollow tubules. It is highly prized among cut rubies and sapphires.

Crystal growing methods

The first single crystal obtained in the laboratory was probably a ruby. To obtain ruby, a mixture of anhydrous alumina containing a greater or lesser amount of caustic potassium with barium fluoride and two-chromium salt was heated. The latter is added in order to cause the color of the ruby, and alumina is taken in a small amount. The mixture is placed in a clay crucible and heated (from 100 hours to 8 days) in reflective furnaces at temperatures up to 1500 ° C. At the end of the experiment, a crystalline mass appears in the crucible, and the walls are covered with beautiful pink ruby crystals.

The second common method of growing synthetic gem crystals is the Czochralski method. It consists in the following: the melt of the substance from which the stones are supposed to crystallize is placed in a refractory crucible made of a refractory metal (platinum, rhodium, iridium, molybdenum, or tungsten) and heated in a high-frequency inductor. A seed made of the material of the future crystal is lowered into the melt on a pull-out roller, and a synthetic material is built up on it to the required thickness. The seed shaft is gradually pulled upward at a speed of 1-50 mm / h with simultaneous cultivation at a rotational speed of 30-150 rpm. Rotate the shaft to equalize the melt temperature and ensure an even distribution of impurities. The diameter of the crystals is up to 50 mm, the length is up to 1 m. Synthetic corundum, spinel, garnets and other artificial stones are grown by the Czochralski method.

Crystals can also grow during condensation of vapors - this is how snowflake patterns are obtained on cold glass. When metals are displaced from salt solutions with the help of more active metals, crystals are also formed. For example, dip an iron nail into a solution of copper sulfate, it will be covered with a red layer of copper. But the formed copper crystals are so small that they can only be seen under a microscope. On the surface of the nail, copper is released very quickly, so its crystals are too small. But if you slow down the process, the crystals will turn out to be large. For this, copper sulfate must be covered with a thick layer of table salt, put a circle of filter paper on it, and on top - an iron plate with a slightly smaller diameter. It remains to pour a saturated solution of sodium chloride into the vessel. Copper sulfate will slowly dissolve in the brine. Copper ions (in the form of green complex anions) will diffuse upward very slowly over many days; the process can be observed by the movement of the colored border. Having reached the iron plate, copper ions are reduced to neutral atoms. But since this process is very slow, copper atoms line up into beautiful shiny crystals of metallic copper. Sometimes these crystals form branches - dendrites.

Crystal growing technology

at home

To grow crystals at home, I prepared a supersaturated salt solution. I chose copper sulfate salt as a starting material. Hot water was poured into a clean glass at a temperature of 50 ° C, the volume was brought to 500 mg. The substance was poured into the glass in small portions, stirring each time and achieving complete dissolution. As soon as the solution was saturated, I covered it and left it in a room where the temperature should be kept constant. As the solution cools to room temperature, excessive crystallization occurs. In the solution, the substance remains exactly as much as it corresponds to the solubility at a given temperature, and the excess falls to the bottom in the form of small crystals. This is how I got the stock solution.

Then I poured the mother liquor into another dish, put the crystals from the bottom there, heated the dish in a water bath, achieving complete dissolution, and allowed it to cool. At this stage, drafts and sudden changes in temperature are not desirable for the solution. Two days later, I examined the contents and noticed that small flat parallelogram crystals had formed on the bottom and walls. Of these, I have selected the most correct crystals.

I again prepared a saturated solution based on the original mother liquor, added a little more (0.5 teaspoon) of the substance, heated and mixed. The solution was poured into a clean and heated dish and allowed to stand for 20-30 seconds so that the liquid calms down a little. When the crystals reached about 2.5 cm in size, I placed them one at a time in flat-bottomed flasks with a pre-filtered and hydrolyzed mother liquor. I washed and cleaned the crystals as needed.

conclusions

All the physical properties due to which crystals are so widely used depend on their structure - their spatial lattice.

Along with solid-state crystals, liquid crystals are currently used, and in the near future they will use devices based on photonic crystals.

Crystals also include jewelry stones from which jewelry is made. Man's attitude to precious stones has undergone changes over many centuries: from deification and use in medicine to demonstrating one's worth or delivering aesthetic pleasure from the beauty and harmony of a stone.

Home-grown crystals can be used in physics lessons to study their physical and chemical properties and their uses.

Artificial algae

To grow artificial algae, I filled a half-liter flask with 50% sodium silicate (water glass) solution. Then she threw a few crystals of ferric chloride, copper chloride, nickel chloride and aluminum chloride into the solution. After a while, the growth of "algae" of bizarre shapes and various colors began. In a solution of iron salt, "algae" are brown, nickel salts are green, copper salts are blue, and aluminum salts are colorless.

Why is this happening? Crystals thrown into the liquid glass solution react with sodium silicate. The formed compounds cover the crystals with a thin film, but due to diffusion, water penetrates through it, the pressure in the crystals increases, and the film bursts.

Through the holes, the salt solution penetrates into the surrounding liquid and quickly recovers with a film. Then the film breaks through again. This is how branching "algae" grow.

Literature:

Akhmetov N.S. Inorganic chemistry - M. Education, 1985

Vasiliev V.N., Bespalov V.G. Information Technology. Optical computer and photonic crystals.

I.S. Zheludov Crystal physics and symmetry. M. Science, 1987

Zhuvinov G.N. Labyrinths of photonic crystals. (Electronic version of the journal).

A.K. Zvezdin Quantum mechanics of trapped photons. Optical microcavities, waveguides, photonic crystals. Nature 2004 No. 10.

O.F. Kabardin Physics: a 10th grade textbook for schools with advanced study of physics. - M. Enlightenment, 2001

Kornilov N.I., Solodova Yu.P. Jewelry stones. - M. Nedra, 1983

Kosobukin V.A. Photonic crystals // Window to the world (Electronic version of the journal).

Completed by: Diana Mosheva, ... Sepich 2012 Passport educational-researchthe project: « Crystals and theirapplication " Leader: student 10 "B" ...

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Diamonds, rubies, emeralds, sapphires and silicon can not only be mined from natural deposits, but also synthesized. Of course, artificial minerals will never have the price of natural ones, but the world demand for them, according to experts, seriously exceeds supply - the volume of production is limited by natural reserves, and the electronics industry, the main consumer of crystals, is developing at a rapid pace. Experts expect that the capacity of the world market for synthesized crystals will reach $ 11.3 billion by 2007. Russia may find itself on the sidelines of this business if it does not take care of investments in specialized production.

Alchemists from Science

Throughout the history of their existence, people have tried not only to find a miracle, but also to make money on it, for example, to get gold from lead or turn rock crystal into diamonds. The most legendary alchemist is the Frenchman Nicolas Flamel, who is credited with obtaining the philosopher's stone (crystalline white powder) that can turn lead into gold. And although Flamel's scientific works did not reach us, documents have been preserved in the Paris archives confirming that the modest bookseller suddenly became rich: he bought 13 houses, large plots of land in Paris and Boulogne, built 12 churches and several hospitals.
However, scientists, of course, do not believe that anyone in the Middle Ages managed to get real gold or diamonds - these are all fairy tales. The revolution took place in the twentieth century, when technology and technology reached the necessary development. No alchemy, purely scientific approach.
As you know, real (natural) gemstones are just solid salts of various metals, the molecules of which are organized into an ordered structure, the so-called. crystal lattice. In nature, crystals have formed over millions of years, deep in the earth's crust, at high temperatures (up to 2000 ° C) and under the colossal pressure of hundreds of thousands of atmospheres. There are very few places where such conditions developed, which explains the rarity of precious stones (for which, in fact, they are valued). To synthesize an analogue of natural minerals, scientists had to reproduce natural phenomena in laboratory conditions, and in an accelerated version. It became possible to obtain such high temperatures and pressures only at the beginning of the last century.
This business turned out to be very high-tech and costly, but not devoid of sense - for objective reasons, mining companies could not satisfy the demand for stones, and the actively developing industry demanded new diamonds, sapphires and rubies. Now the world market for synthesized stones is estimated at more than $ 6 billion; approximately 86% goes to crystals obtained for the needs of industry, 14% goes to meet the needs of jewelers.
Almost all types of crystals are synthesized in Russia, but in small amounts. In Troitsk near Moscow, diamonds are grown, in Zelenograd - sapphires, garnets, rubies, near Nizhny Novgorod - rubies, in Novosibirsk - emeralds. Mikhail Borik, Senior Researcher of the Scientific Center for Laser Materials and Technologies of the I.O. A.M. Prokhorov: This is how it happened historically: in which city in Soviet times a method was developed for obtaining a particular crystal, it is still being synthesized there. There were practically no new productions. But the demand for artificial crystals is constantly growing, and there are not enough specialists.

Khachik Bagdasarov: "Equipment for growing crystals costs $ 300-400 thousand and starts to pay off already in the second year"

Ruby Fever

In 1902, the French engineer Verneuil, after numerous unsuccessful attempts, finally managed to synthesize a small ruby crystal weighing 6 g. In fact, it became the very first artificial gemstone identical to the natural one. From the point of view of commerce, Verneuil's desire to get exactly the ruby was quite justified - in nature there are very few rubies. Now in the world about five tons of rubies are mined annually, while the demand is in the hundreds of tons (mostly they are needed not by jewelers, but by watchmakers).
The starting material, the so-called. the charge (powder of aluminum oxide with an admixture of chromium), Verneuil passed through a gas burner with a temperature of 2150 ° C, and the resulting melt with a decrease in temperature began to slowly crystallize, turning into ruby. The obvious simplicity and reliability of the Verneuil method led to the rapid organization of industrial production of ruby crystals, first in France, and later in practically all highly developed countries. It is thanks to synthetic rubies that a number of discoveries have become possible. For example, a laser was invented on the basis of a ruby, which made it possible to accurately measure the distance from the Earth to the Moon, use outer space for communication, etc.
Later it turned out that using the technology of synthesis of rubies, it is possible to obtain other valuable crystals - sapphires and garnets: first, the initial substance melts at high temperatures, then supercools and as a result crystallizes. The technology is simple and, what is most interesting, is accessible, as he assures Khachik Bagdasarov, Head of the Department of High-Temperature Crystallization, Institute of Crystallography. A.V. Shubnikov Russian Academy of Sciences (engaged in the synthesis of sapphires, rubies and garnets). It is all the more strange that in Russia only a few companies and laboratories at research institutes are engaged in crystal synthesis. Now the most cost-effective is the Bagdasarov method, invented at the Research Institute of Crystallography of the Russian Academy of Sciences. Khachik Bagdasarov: I was the first to use the so-called horizontal directional crystallization for the synthesis of garnets back in 1965, and this technology turned out to be significantly more economical compared to the widespread Verneuil method. Everything is explained simply: in the cost price of crystals, the majority is occupied by electricity due to the need to maintain high temperature and pressure. When a horizontal plate is synthesized, rather than a vertical rod, much less energy is expended.
Nevertheless, according to experts, the world's demand for rubies, sapphires and garnets, spurred by the development of the electronics industry, is still not satisfied. Sapphire glasses are needed not only by watch companies (especially Swiss ones), for the production of windows for spaceships and homing missile heads, but also by manufacturers of mobile phones, whose annual demand is about 6 billion glasses! The best lasers are produced with the help of garnet, activated by neodymium ions. Jewelers now especially appreciate green and pink garnet, which are obtained thanks to the addition of thulium or erbium, respectively (1 kg - $ 20-25).
However, the demand for refractory crystals is growing only from Western companies, in Russia it tends to zero due to the decline in electronics production. Khachik Bagdasarov: Most of all, sapphire is in demand by Korean (for the needs of the watch industry) and Japanese (for optics) firms. In total, about a thousand tons of sapphires are synthesized in the world annually. Russia is an obvious outsider in this matter. For example, if before the 90s about 180 tons of rubies and about 50 tons of sapphires were grown in the USSR, now there are only 10-20 tons of ruby, about 20 tons of sapphire and 100-120 kg of pomegranates.
According to Igor Alyabyev, deputy director of the company "ROKOR" (engaged in the production of sapphire products), the cost of growing 1 kg of sapphire crystals is about $ 600, from which you can get 100 plates weighing 5 g and costing $ 12 each. A synthetic ruby for the jewelry industry costs about $ 60 per kilogram (for comparison: one carat (0.2 g) of natural stone - $ 50), for technical purposes - from $ 70 per kilogram. Moreover, the larger the single crystal, the more expensive it is, and the synthesis cost is lower. Thus, a single crystal of sapphire weighing up to 6 kg is estimated at $ 5-10 thousand, while the cost of one kilogram is about $ 200 (and the selling price of 1 kg is $ 500). Business profitability is easy to calculate, and this order of numbers applies to all three crystals mentioned above. The world volume of sapphire synthesis is about a thousand tons.
Now the largest production of synthetic rubies (hundreds of millions of carats per year) are concentrated in Switzerland, France, Germany, the USA and Great Britain. Special crystallization units are manufactured by the Taganrog Plant of Electrothermal Equipment. Khachik Bagdasarov: Domestic equipment costs about $ 50 thousand, Western - $ 300-400 thousand. An important point: it makes sense to create a production with at least ten units for profitable volumes. One production cycle takes two to three days, during which 2 kg of crystals can be removed from one installation. The equipment will "beat off" in the second year.

Stone identification

As Bagdasarov assures, the structure of artificial and natural stones (as well as appearance) is identical, and it is quite natural that laboratory synthesized precious minerals are of interest to counterfeiters. “Ten years ago, a Hindu came to me, asked me to synthesize rubies indistinguishable from a natural stone. But after a while, the Hindu disappeared, they say, the miners of natural stones removed him. Nevertheless, a precious stone identical to a natural stone is not difficult for us and the buyer will never distinguish it from the natural one, "he says.

Vera Bogdanova, expert gemologist of the Adamas Jewelry House: In nature, large gemstones are rare, their discovery is of particular historical value, and the outstanding stone is given the name of the area where it was found. Jewelers also know: with natural stones there is much more trouble in processing, most are rejected due to cracks and defects, and only a few are suitable for jewelry crafts. Plus the higher natural cost. The fact that jewelers use artificially grown stones supposedly as natural ones has received wide publicity relatively recently. They often bring jewelry inherited from grandmothers to me for examination, and their owners are very surprised when they learn that the stone is artificial.
Mikhail Borik: In jewelry stores, there are enough products from rubies and sapphires obtained in laboratory conditions. The average buyer will not be able to tell them apart by eye. Even most of the sellers in jewelry stores themselves don't know what they are selling. True, well-known jewelry manufacturers, who value their reputation, never hide where synthetics are and where nature is. Nevertheless, when buying an expensive piece of jewelry, you should always ask for a certificate for the authenticity of the stone.
As Khachik Bagdasarov assures, when in the mid-50s science came close to the synthesis of diamonds, special departments were created under the Ministries of Finance of all developed countries to monitor the progress of scientists. Imagine that synthetic diamonds indistinguishable from natural diamonds rush into the market - the economies of a number of countries will simply collapse, and the strategic diamond reserves of a number of countries will turn into dust.

The Driller's Best Friends

Every year, an average of 100-110 million carats (about 20 tons) of diamonds are mined in the world, and on the world market 1 carat of natural diamond costs from $ 55, however, most of the stones for jewelry are not suitable due to defects, cracks and impurities, but on the other hand it is in demand in the industry, primarily in the processing industry, in need of high strength characteristics of the mineral. Nevertheless, according to experts, the tool, metal and stone processing industries need about four times more diamonds than they are mined, and in a number of high-tech areas (in the manufacture of electronic elements, ultraviolet radiation sensors), natural raw materials are almost impossible to use due to the presence of 98% of natural diamonds contain nitrogen inclusions. Artificial diamonds are devoid of all natural defects, because man managed to create ideal synthesis conditions for them.
In 1953-1954, scientists from two independent research groups - the Swedish company ASEA and the American General Electric for the first time managed to synthesize diamonds less than 1 mm in size. For this, a mixture of graphite and iron was melted at a temperature of about 2500 ° C, and then the resulting melt was placed in a solid compressible medium at a pressure of 70-80 thousand atmospheres. Vasily Bugakov, Deputy Director of the Institute for High Pressure Physics (Troitsk; engaged in the synthesis of diamonds): A synthetic diamond, like a natural one, is measured in carats, and costs about $ 10 per carat on the world market, five times cheaper than a natural one. At the same time, the cost of raw materials and electricity is only $ 5 per carat. Russia now ranks third in the production of synthetic diamonds, producing 25 million carats annually.
True, so far diamonds are being synthesized only in the interests of the industry - artificial gem-quality stones are still superior to natural ones in their cost price. In addition, the size of synthesized diamonds is limited to 3 mm, because while there are simply no materials that can withstand such high temperatures and pressures with large chamber volumes. An installation for the synthesis of 200 kg of diamonds per month can be purchased for $ 30,000.
Unlike diamonds, synthesized emeralds are used exclusively for jewelry production, although, objectively, they do not differ in particular beauty due to the lack of dispersion, i.e. decomposition of sunlight into a spectrum, and are valued solely because of their rarity, as well as small production volumes (only 500 kg of natural emerald are mined in the world every year, of which 300 kg are in the Russian Urals).
Emerald is obtained, in contrast to the bulk of crystals, not from the raw material melt (emerald decomposes when heated), but from a solution of boric anhydride, synthesizing in special hydrothermal chambers at relatively low temperatures (about 400 ° C) and pressure (about 500 atmospheres). A hydrothermal installation for the synthesis of emeralds is relatively inexpensive ($ 5-10 thousand), but low-productivity (up to 10 kg of crystals per month). The prime cost of 1 kg of emerald is $ 100-200, and the selling price of one carat is approximately equal to the price of a natural stone - about $ 2.
Annually in Russia, at an enterprise in Novosibirsk, up to 100 kg of emeralds are synthesized, in the world no more than one ton.

Contrary to nature

In 1968, Russian physicists obtained a transparent crystal that did not have a natural twin, and named it cubic zirconia in honor of their Physics Institute of the Academy of Sciences (FIAN), although the first experiments on the synthesis of such crystals were carried out back in the 1920s by French chemists.
The purpose of the synthesis of cubic zirconia was to obtain a crystal for use in lasers. True, cubic zirconia could not surpass garnet in its "laser" properties, but its unusual beauty, multicolor and cheapness were appreciated by jewelers (up to 98% of cubic zirconias are produced for their needs). For surgery, a scalpel with cubic zirconia is produced ($ 500) - the fact is that some people are allergic to metal, and the cubic zirconia blade allows you to avoid an allergic reaction.
Cubic zirconia are synthesized from a mixture of oxides of zirconium, aluminum, sodium. The process is practically waste-free, because shards and unsuccessful crystals are re-melted. From 100 kg of raw materials per day using a high-frequency generator (about $ 50 thousand), up to 30 kg of cubic zirconia crystals are obtained. The transparency of the stone depends on the melting point - the higher the temperature, the more transparent the crystal. Elena Lomonova, Head of the Laboratory of the Scientific Center for Laser Materials and Technologies of the General Physics Institute of the Academy of Sciences: It is easy and pleasant to grow cubic zirconia, and the addition of certain impurities allows you to create unique crystals of flowers that do not occur in nature, for example, lavender, or to achieve unusual optical effects, such as a color change when lighting changes - the so-called. alexandrite effect.
For a long time, the USSR remained a monopolist in the production of cubic zirconia, dictating prices, at first reaching $ 3 thousand per kilogram (although the issue of the priority of cubic zirconia production is very controversial, the Americans even challenged it in court). Vyacheslav Osiko, Director of the Scientific Center for Laser Materials and Technologies, GPI: Cubic zirconias were fraudulently taken out of the USSR, passing them off as diamonds. To combat jewelry fraud, even KGB officers were trained to distinguish gemstones from counterfeits. For the ability to play with all the colors of the rainbow, jewelers call cubic zirconia an impudent stone. Now more than 1,000 tons of cubic zirconia are synthesized all over the world annually, and their price has dropped to $ 60 per 1 kg. At the same time, the cost of a kilogram of cubic zirconia, according to experts, is about $ 30.

Crystal of the future

However, in terms of the growth of world production volumes and profitability, synthesized silicon, which is indispensable in the microelectronic industry, solar batteries and other technological devices, will not be able to keep up with any crystal in the foreseeable future. More than 30 thousand tons of silicon are produced annually in the world, and according to forecasts, by 2010 this figure will double (now silicon crystals occupy 80% of the world market of all artificial crystals). Nevertheless, according to experts, silicon in the world is sorely lacking due to the growth in the production of computer and microprocessor technology.

Vyacheslav Osiko: "At one time, cubic zirconias were exported, passing them off as diamonds"

In Russia, the consumption of silicon, as well as its production, is extremely insignificant, all due to the same reason for the reduction in the production of electronics. And if in 1990 360 tons of silicon were grown in the USSR, then last year in the Russian Federation only 270 tons, of which only 50 tons were for the domestic market. Now 1 kg of silicon costs $ 100, while the profitability of production, according to experts, exceeds 100%.
As Khachik Baghdasaryan assures, investments in the production of silicon and in the products for the production of which it is needed may turn out to be a gold mine, and the raw materials for its synthesis (ordinary sand) are literally underfoot: “Three years ago in Germany, I met a young entrepreneur who started production of solar cells literally from one soldering iron, and now having an annual profit of € 20 million. Silicon has long become a strategic material that determines the scientific and technological development of the country. "
The head of the laboratory of the State Scientific Center for Rare Metals, Mikhail Milvidsky, claims that scientists around the world are working to increase the volume of silicon production, because solar energy is cheap, environmentally friendly and endless compared to oil, gas and coal. Khachik Baghdasaryan: According to the forecasts of many scientists, by the end of the 21st century, up to 80% of the world's electricity will be generated from solar or wind energy. And silicon in the first case is an irreplaceable material.
True, the "nuclear" lobby in Russia is not interested in this, and therefore, if the movement in the world towards safe and environmentally friendly methods of generating electricity has long been obvious, our processes are reversed.
OLESYA DEYNEGA, DMITRY TIKHOMIROV

FIELD STUDIES

Something about diamonds

The most expensive natural stone is diamond, which is currently being mined in 26 countries (the largest of them are Russia, Botswana and South Africa). An average of 100-110 million carats (20 tons) of diamonds are mined in the world annually. Their high price ($ 55 per carat) is explained not only by the characteristics of the stones, but also by the level of monopolization in trade: as you know, the De Beers Corporation controls 70-80% of natural diamonds supplied to the market. According to the Ministry of Finance, the volume of diamond production in Russia in the first half of 2005 amounted to 17.7 million carats at an average price of $ 51 per carat. The export of rough natural diamonds from the territory of the Russian Federation in January-September 2005 amounted to 23.6 million carats, of which the share of gem-quality diamonds is 20-25%.
The largest gem diamond in the world is considered to be Cullinan, with a mass of 3106 carats (621.2 g), it was found in 1905 in the Transvaal (South Africa). Subsequently, nine large diamonds were made from it (the largest - "Star of Africa", 530.2 carats) and 96 small ones, and 66% of the original mass of the crystal was lost during the cutting process.
Diamonds (cut diamonds) are evaluated according to four main criteria (the so-called four "C" system): color, clarity, cut and proportion (cut), carat weight (carat weight). The most valuable are diamonds with the so-called high color, i.e. colorless, but the presence of even a slight shade of yellow, brown or green can seriously reduce the cost of the stone. In colorless diamonds, the most valued round cut (in this case, they have 57 facets), which allows you to maximize the brilliance and play of the stone.

Prejudice

The secret power of stones

Since ancient times, precious stones have served as decorations and talismans. For example, the Egyptians willingly wore jewelry made of emeralds, turquoise, amethysts and rock crystal. The Romans put diamonds and sapphires above all else. Often the stone indicated the profession of its owner. Sailors believed that emerald protects from dangers on long voyages, tourmaline inspired artists, amethyst protected clergy from temptation. It is believed that only the stone that was donated or inherited can be a talisman.
The belief in the healing properties of precious stones was also widespread. In the Middle Ages, a jeweler had to be not only an artisan and a merchant, but also a doctor, able to pick up a stone for healing in case of illness.
Astrologers argued that each gem belongs to a specific zodiac sign and people should only wear stones of their own sign. Wearing a stone that does not correspond to the sign of the zodiac under which its owner was born has a bad effect on fate. Aries should wear diamonds, Taurus should wear sapphires, Cancers and Capricorns need to get a ring with an emerald for happiness, but astrologers recommend that Pisces should not wear stones - it can drag them to the bottom.

Artificial stones have long gained popularity in jewelry. Indeed, for a jeweler, the value of a stone is determined not only by its deficit in nature. A number of other characteristics play an important role:

Colour;
light refraction;
strength;
carat weight;
the size and shape of the edges, etc.

The most expensive artificial gemstone is Cubic Zirconia (synonyms: daimonsquay, djevalite, zirconium cube, shelby). Its price is low - less than $ 10 per 1 carat (that's 0.2 grams). But it's worth noting that the price rises exponentially with the increase in carats. For example, a 10 carat diamond costs 100 times more than a 1 carat diamond.

Artificial crystals of gemstones can be grown at home. Most of these experiments do not require special training, you do not need to equip a chemical laboratory and even purchase special reagents.

To gain experience in growing crystals, start small. We will share a technique for growing beautiful crystals from everything that you can actually find in your own kitchen. You don't need any additional inventory at all, because everything you need is definitely on the shelves. Let's also consider the technology of growing artificial rubies at home!

How to Grow Ruby Crystals Synthetically?

Growing ruby crystals can even be a home business option. After all, beautiful synthetic stones are already in great demand among buyers, so if the project is successfully implemented, they can bring you a good profit. Synthetically grown stones are used by jewelers and are also widely used in engineering.

Ruby crystals can be grown using the standard method by selecting the correct salts. But this will not be as effective as in the case of salt or sugar, while the growth process takes much longer. And the quality will be questionable. After all, natural ruby on the Mohs scale of hardness is second only to Diamond, occupying the honorable 9th place. Naturally, when it comes to business, in most cases they use a different method developed over 100 years ago in France.

You will need a special apparatus named after the inventor of this method, that is, the Verneuil apparatus. It can be used to grow ruby crystals up to 20-30 carats in size in just a few hours.

Although the technology remains about the same. Salt of aluminum dioxide with an admixture of chromium oxide is placed in the storage of an oxygen-hydrogen burner. We melt the mixture, observing how the ruby actually grows "before our eyes".

Depending on the composition of the salt you choose, you can adjust the color of the crystals, producing artificial emeralds, topaz and absolutely transparent stones.

Working with the device will require your attention and some experience, but in the future you will get the opportunity to grow crystals that fascinate with their beauty, transparency and play of color. In the future, such masterpieces are well served by cutting and grinding, respectively, they can be used for their intended purpose.

It is worth noting that cultured crystals are not gemstones, so even if you decide to start a business of growing them, it will not require additional licensing from you.

The design of the device is simple, you can easily make it yourself. But on the Internet there are already enough craftsmen offering drawings of the original installation, as well as its improved versions.

Set for growing ruby crystals at home

The very principle of rubies production technology is quite simple and is schematically shown in the figure below:

Understanding the principle of operation, any device no longer seems so complicated. One of the sample drawings of the Verneuil apparatus:

This technology can also be used to grow other expensive artificial stones, such as "Blue Topaz", etc.

Growing salt crystals at home

The easiest and most affordable experiment you can do is create beautiful salt crystals. To do this, you will need several items:

Common rock salt.
Water. It is important that the water itself contains as little of its own salts as possible, and preferably distilled.
The container in which the experiment will be carried out (any can, glass, saucepan will do).

Pour warm water into the container (its temperature is about 50 ° C). Add kitchen salt to the water and stir. After dissolving, add again. We repeat the procedure until the salt stops dissolving, settling to the bottom of the vessel. This indicates that the saline solution has become saturated, which is what we needed. It is important that during the preparation of the solution its temperature remains constant, does not cool down, so we can create a more saturated solution.

Pour the saturated solution into a clean jar, separating it from the sediment. We select a separate crystal of salt, and then we place it in a container (you can hang it on a thread). Experiment completed. After a few days, you will be able to see how your crystal has grown in size.

Growing sugar crystals at home

The technology for producing sugar crystals is similar to the previous method. You can dip a cotton cord into the solution, then sugar crystals will build up on it. If the crystal growth process has become slower, then the concentration of sugar in the solution has decreased. Add granulated sugar to it again, then the process will resume.

Note: if you add food coloring to the solution, then the crystals will become multi-colored.

You can grow sugar crystals on sticks. To do this, you will need:

ready-made sugar syrup, prepared similarly to a saturated saline solution;
wooden sticks;
some granulated sugar;
food coloring (if you want colorful candies).

Everything is very simple. Dip a wooden stick in syrup and roll in granulated sugar. The more grains stick, the more beautiful the result will be. Let the chopsticks dry thoroughly, and then proceed simply to the second phase.

Pour the saturated hot sugar syrup into a glass, place the prepared stick there. If you are preparing multi-colored crystals, add food coloring to the hot prepared syrup.

Make sure that the stick does not touch the walls and bottom, otherwise the result will be ugly. You can fix the stick with a piece of paper, putting it on top. The paper will also serve as a lid for the container, which will prevent any foreign particles from entering your solution.

In about a week, you will have lovely sugar lollipops. They can decorate any tea party, delighting not only children, but also adults!

Growing crystals from copper sulfate at home

Crystals from copper sulfate are obtained in an interesting shape, while having a deep blue color. It is worth remembering that copper sulfate is a chemically active compound, therefore, crystals from it should not be tasted, and caution should be exercised when working with the material. For the same reason, only distilled water is suitable in this case. It is important that it is chemically neutral. Be careful and careful when handling copper sulfate.

In this case, the growth of crystals from vitriol occurs in fact according to the same scheme as in the previous cases.

When placing the main crystal for growing in the solution, you need to make sure that it does not come into contact with the walls of the dish. And do not forget to monitor the saturation of the solution.

If you have placed your crystal at the bottom of the vessel, then it is worth watching so that it does not touch other crystals. In this case, they will grow together, and instead of one beautiful large sample, you will get a mass of indistinct shape.

Helpful advice! You can independently adjust the size of the facets of your crystal. If you want some of them to grow more slowly, you can grease them with petroleum jelly or grease. And for the preservation of the sky-blue handsome man, you can process the edges with transparent varnish.

There are 3 weight categories of diamonds:

Small. Weight 0.29 ct
Average. Weight from 0.3 to 0.99 carats
Large. Diamonds over 1 carat.

Stones weighing from 6 carats are admitted to popular auctions. Stones weighing more than 25 carats are given their own names. For example: "Winston" diamond (62.05 carats) or "De Beers" (234.5 carats), etc.