Properties and production methods of artificial diamonds. How to make a diamond yourself and is it possible

For the direct conversion of graphite to diamond, even more extreme conditions are required compared to the method using a metal-solvent. This is due to the high stability of graphite due to the very strong bonds of its atoms.

The results of the first experiments on direct graphite-diamond transformation by P. De Carlne and J. Jameson of Allied Chemical Corporation were published in 1961.

To create pressure, a high-power explosive was used, with the help of which a temperature of about 1200 ° C and a pressure of about 300,000 atm were maintained for about a millionth of a second (one - "microsecond). Under these conditions, a certain amount of diamond was found in the graphite sample after the experiment, although The crystallites obtained are in size (100 A = 10 nm, or one hundred-thousandth of a millimeter) comparable to the "carbonado" found in meteorites, the formation of which is explained by the impact of a powerful shock wave arising from the impact of a meteorite on the earth's surface.

In 1963, Francis Bundy of General Electric succeeded in direct conversion of graphite to diamond at a static pressure in excess of 130,000 atm. Such pressures were obtained on a modified belt unit with a larger outer surface of the pistons and a smaller working volume. To create such pressures, it was necessary to increase the strength of the power parts of the Installation.

The experiments included spark heating of a graphite bar to temperatures above 2000 ° C. Heating was carried out by pulses of electric current, and the temperature required for diamond formation was maintained for several milliseconds (thousandths of a second), i.e., much longer than in De- Carly and Jameson.

The sizes of the newly formed particles were 2–5 times larger than those obtained under shock compression. Both series of experiments provided the necessary parameters for constructing a phase diagram of carbon, graphically showing the temperature and pressure ranges at which diamond, graphite and melt are stable.

Interesting experiments were carried out by Bundy and J. Casper, who used single crystals of graphite instead of ttolikrn-steel material. Diamond crystals in their first experiments had the usual cubic crystal structure.

Even De Carly and Jameson drew attention to the fact that the transformation into diamond occurs more easily when the graphite particles in the samples have an elongation along the so-called c-axis, i.e., perpendicular to the hexagonal layers. When Bundy and Casper placed the single crystals so that pressure was applied along the c-axis and measured the resistivity of the crystals under pressure, it turned out that the resistance increased when a pressure of 140,000 atm was reached.

This was attributed to the transformation of graphite into diamond, although when the pressure was removed, the reverse transformation into graphite took place. However, when this procedure was accompanied by heating the sample to 900 ° C and higher, crystallites of a new high-pressure phase were formed, having a hexagonal structure rather than the usual cubic one.

Hexagonal carbon has also rarely been found in natural samples, especially in meteorites. It was named Lonsdeplit in honor of Kathleen Lonsdeil of the University of London for her great contributions to crystallography, in particular to the study of diamond.

1968 to H.R. Cowen. B.V., Dunnington and A.H. Holzman from the company "DuPont de Nemur" was granted a patent for a new process, which consists in shock compression of metal blocks, for example, iron castings, containing small inclusions of graphite (at pressures exceeding 1 million atm. )

Metal, whose compressibility is less than that of graphite, serves as a refrigerator, a rapidly cooling inclusion.

This prevents the reverse transition of the diamond formed under the action of the shock wave into graphite after the passage of this wave — a trend characteristic of experiments with single crystals under cold compression. The final product obtained using this technology is partially hexagonal carbon, which also confirms the tendency to form lonsdaleite under very high pressures and relatively low temperatures. The material produced in this way is used as a grinding powder.

From time to time, studies are reported to modify one or the other of these methods. For example, L. Trueb applied the De-Carly-Jameson principle to create a pressure of 250,000–450,000 atm for 10–30 μs, followed by heating after impact to 1100 ° C. We used graphite in the form of particles with a diameter of 0.5–5 µm, and the resulting diamonds had the same dimensions.

However, it has been established that these particles are formed by very small (from 10—40 to 100—1600 A) cubic diamonds. There is currently no indication that Allied Chemical Corporation products are being marketed commercially.

The method developed by this company to compete successfully with the dilator method and the method of the DuPont de Nemur company needs further improvement. A potential advantage of shock compression techniques is that explosion is a cheap way to generate high pressures.

How is graphite different from diamond?

Both diamond and graphite are modifications of carbon.

Diamond:

Graphite:

However, there are a lot of differences:

1. Diamond is the hardest known substance (10 on the Mohs scale), graphite is one of the softest (1-2).

2. Diamond - crystalline cubic polymorphic modification of native carbon.
density about 3.5 g / cc, high refractive index among gemstones (2.417). semiconductor. large transparent diamond crystals are first class gemstones.

Graphite - the most widespread and stable polymorphic hexagonal modification of carbon in the earth's crust. the structure is layered. density approx. 2.2 g / cm3. fireproof, electrically conductive, chemically resistant.

3. The difference is also visible when analyzing the creation of artificial aliases: the technology for the production of artificial diamonds is rather complicated. synthesize diamonds at a temperature of 1200-2000 ° C and a pressure of 1000-5000 MPa (50-60 thousand atmospheres) from graphite powder mixed with powdered iron, nickel, chromium. Diamonds crystallize due to the fact that the melt at high pressures is undersaturated with respect to graphite and supersaturated with respect to diamonds.

By the way, graphite can also be obtained artificially: heating anthracite without air.

4. Diamonds usually fluoresce in X-rays and ultraviolet rays. diamonds are transparent to x-rays. this makes it easier to identify a diamond: some glasses and colorless minerals, sometimes similar in appearance to it, are opaque to X-rays of the same wavelength and intensity.

5. About the crystal lattice:

The difference is visible to the naked eye. R The diamond grid is very durable: carbon atoms are in it along the sites of two cubic lattices with centered faces, very tightly inserted into one another (a = 3.5595 A).

About graphite: the bond between atoms is strong, covalent type; between layers - weak, residual metal type.

Synthetic diamonds, or polished diamonds, are artificially grown diamonds that have arisen as a result of human activity, belonging to the class of industrial products. These stones have the same atomic structure, chemical composition and physical properties as real mined diamonds, and they are also made from the same materials, namely: pure carbon, crystallized into an isotropic cubic form.

The unique properties of synthetic diamonds make them an excellent product for a surprisingly diverse range of applications in industry, science and everyday life. The combination of properties makes artificial diamond one of the most impressive materials in the world.

The absence of crystal lattice defects is considered the main outstanding property of diamond. Crystal purity and perfection make diamonds transparent, high thermal conductivity is relevant to the industrial sector, and hardness, optical dispersion and chemical resistance have made diamond a popular gemstone. Optical dispersion is inherent in all diamonds; other characteristics may vary depending on the method and conditions of creation.

Diamond properties include:

Optical properties and color of synthetic diamonds

Artificial diamond has the widest spectral range of all known materials, from ultraviolet to far infrared and microwave. In combination with mechanical and thermal properties, diamonds are ideal for the production of laser optics and the use of lasers.

Diamonds can be found in every color imaginable, with countless hues, tones and saturation levels. Color arises from inclusions at the level of atoms, stuck in the crystal lattice of the stone.

Color consists of 3 main components:

Laboratory-created diamonds are grown in three stunning colors - yellow, blue and colorless. These colors are permanent, never change, do not fade over time or due to temperature exposure.

Let's consider in more detail:

Gem substitutes

A diamond substitute is a material whose appearance strongly resembles real diamonds. Unless the expert examines the substitute at close range, the imitation is almost indistinguishable from a real diamond. Counterfeit stones, unlike originals, do not have a carbon crystal lattice.

Counterfeiting diamonds existed as early as 1920 - spinel forms such as corundolite and radiant were discovered, and decades later - forms of strontium titanate, sapphire, rutile and other minerals that led the world market for fake diamonds.

In recent years, a new class of imitation diamonds has emerged with a significant improvement in quality. One of the most common imitators for diamonds is zirconia, or cubic zirconia.

Discovered in 1976, the material ranks second after moissanite in the production of fake diamonds. The material is mixed with a stabilizing agent such as calcium oxide or yttrium oxide. Cubic zirconias are available in the market in a variety of colors and clarity / brightness.

Colorless cubic zirconia is one of the most expensive because it is the hardest to produce.

The ratio of the relative density of the mined diamond is lower than that of cubic zirconia, this factor is used as an effective check for the authenticity of a diamond, carried out by means of a special device resembling the feather of a pen. The fake is heavier and takes on a characteristic greenish-yellow color when exposed to shortwave ultraviolet radiation.

Moissanite is brighter than diamond and harder to distinguish from real diamond than cubic zirconia. It is chemically known as silicon carbide or carborundum. Henry Maussan received the Nobel Prize for his discovery of moissanite material after finding fragments of a meteorite in a crater. The properties of maussanite make it possible to pass it off as a real diamond, even with the smallest human effort and modern processing methods.

A buyer of a gem can be easily deceived by buying a replica instead of a diamond. Natural diamonds have a rough surface and black inclusions, while moissanite has no cosmetic defects, the aesthetic qualities of the material are highly rated.

Some other diamond substitutes available today are zircon, white topaz, synthetic rutile, white sapphire, and yttrium aluminum garnet. These polycrystalline synthetic diamonds are produced by chemical vapor deposition at low temperature and low pressure.

The substitute also includes a glass diamond, a simulant originally made from rock crystal, and today from glass or acrylic polymers.

Back in the 18th century, the jeweler from Alsace, Georg Friedrich Strass, from whose name the material was named, came up with the idea to apply a metal powder to the underside of lead glass (crystal). Today some companies use the metal deposition method to obtain an even, thinnest coating.

Crystal rhinestones are produced by the Austrian company Swarovski and the Czech company Preciosa.

Artificial stone growing technology

The method of obtaining artificial diamonds is carried out by means of manual temperature and pressure control in laboratory conditions. Today, there are 2 options for obtaining technogenic stones, large enough to create jewelry:

How to grow a diamond at home?

In order to conduct an experiment and learn how to make a diamond at home, you will need:

Let's consider the process in stages:

Note: Sparks may appear in the microwave due to the oil, this is okay, the sparks will stop appearing after a few minutes. The temperature inside the mug is incredibly high, so you do not need to touch the structure until it cools completely.

The US Federal Trade Commission insists that synthetic diamonds be laser engraved. Another available way to differentiate between a mined natural diamond and a stone grown in a laboratory is the use of a scientific apparatus and a program that studies and fixes the characteristic crystal lattice.

To date, the largest synthetic diamond in Russia is a 10.07-carat dark blue emerald cut stone grown by the Russian diamond company New Diamond Technology.

The stone was obtained by using high temperatures and high pressure. The International Gemological Institute has certified this diamond as having a clarity of Si1, when inclusions are visible to an experienced grader with 10x magnification, the stone has a light glow, excellent proportions, symmetry and gloss.

- Onriom

Manufacturing artificial diamonds requires several challenging conditions. Recently, using computer simulations, scientists have been able to recreate the process of turning graphite into diamond in the smallest detail.

Image caption: Using the latest scientific method, scientists for the first time accurately reproduced the process of converting graphite into diamond.

The transition consists of several stages, ranging from the formation of a diamond "seed" inside the graphite, and ending with a complete transformation into a real diamond under the influence of high pressure.

There are far more differences between these two varieties of naturally occurring elemental carbon (dark gray graphite and lustrous diamond) than between either or virtually any other material.

A significant difference in the strength of diamond and graphite is mainly associated with their crystal structure - cubic in the case of diamond and hexagonal in the case of graphite.

This difference makes diamond the hardest known material, in contrast to the relatively soft graphite. It is due to their high strength that diamonds are in demand not only as precious stones - they are used in industry for grinding and sawing especially hard materials.

Complex transformation

For the first time, it was possible to artificially obtain a diamond from graphite 60 years ago. But it did not come to production on an industrial scale. The fact is that the necessary conditions for its production are high pressure and high temperatures, this process is very long and requires high energy costs. It includes a forced change in the structure of carbon, a change in the location of its electrons.

Four bonds of carbon atoms should form instead of three, and the state of carbon should change from energetically “comfortable” to energetically “uncomfortable”, dense state. For this to happen, carbon must overcome a strong energy barrier.

How exactly such a transformation takes place, and at what point carbon becomes diamond - until now science could not give a clear answer to this question.

Michel Parrinello, professor of computational sciences at the Higher Technical School of Zurich and the University of Lugano, and his team, using the method of computer modeling, have successfully recreated the process of transforming graphite into diamond in virtual space.

Simplification gives a false picture

In the past, scientists have tried to simulate the transition phase using the so-called "Car-Parrinello method". Using this method, it is possible to approximately determine the structure and energy state of electrons at each position in the ion and, thus, simulate the situation with the breaking and subsequent formation of new ionic bonds.

The 25-year-old method was developed in collaboration between Parrinello and Roberto Kar. “However, building an accurate model of the transition from graphite to diamond would be prohibitively expensive when you consider the enormous number of atoms to be tracked,” Parrinello says.

The researchers tried to simplify this method by significantly reducing the number of atoms used in the simulation. But, according to Parrinello, with such a simulation, the entire transformation phase of graphite looks like it happens instantly, as if on command, and not in stages.

A completely different picture was obtained using a new, recently developed modeling method. Using a supercomputer from the Swiss National Supercomputing Center, scientists have calculated tens of thousands of atom configurations with smooth energy transitions.

This means that the configurations of atoms have a wide range of possible energy states. After scientists interpolated their energy state and used the obtained data as a basis for modeling, it became obvious that first a diamond "seed" is formed, which then, under the influence of high pressure, gradually changes its hexagonal graphite structure to cubic.

Modeling the transformation phase using the latest method allowed us to make another discovery: structural defects in the crystal lattice of graphite reduce the number of barriers that must be overcome to form a diamond "seed" ... Therefore, structural defects can increase the rate of the transformation process.

This method can be used wherever there is a need to visualize phase transitions - emphasizes Parrinello.

How to make a diamond in Minecraft?

Diamond in Minecraft is considered the most valuable ore. Without it, you will not be able to make most of the really necessary items. There are several ways to make a diamond in this game. More details about them will be written below.

Mining diamonds in Minecraft

In Minecraft, a diamond can be mined. To do this, you must arm yourself with an iron pickaxe. Diamonds can be found 1 - 16 blocks from the admin. As a rule, a mineral is located in veins of 1 - 8 blocks. Most often there are 2 - 3 blocks together. The easiest way to find a diamond is to go down into the caves to the required depth. However, the caves are fraught with many dangers, because you can run into an evil mob or fall into the lava. For this reason, care must be taken.

To find a diamond in Minecraft, you need to dig a passage down and go to level 16. Then make a corridor 20 blocks in length, then on both sides of it dig corridors through the block. It may happen that you will not find diamonds; in this case, you will need to go down below and continue working. Dig all the way down to the admin and you're bound to stumble upon a diamond mine. When it is found, dig in it from all sides. Such a measure will preserve the find, and not a single diamond will fall into the lava.

How can you make a diamond in Minecraft?

Not everyone wants to go down into a cave and search for diamonds. This element can be easily done. You just need to install the Industrial Craft2 mod. You can download it here: bendercraft.ru You will also need the following components to craft diamonds:

Convert all coal to coal dust using a grinder. Make a coal ball out of coal and flint, and then squeeze it in the compressor. Then create a block of coal, squeeze it. This will result in a diamond. As you can see, making your own diamond in Minecraft is not difficult, you just need to install the mod.

Where can you find diamonds in Minecraft?

If you don't want to make diamonds and go down into the cave, you can look for this element. He can be stored in chests that are in treasuries, temples, and NPC villages. Here are just a few of them, and they come across very rarely.

You can also try increasing the amount of diamonds available. However, this requires an enchantment table. If you put the "luck" enchant on a pickaxe, then when you break a block of diamonds, you will receive more units.

Where can diamonds be used?

Diamond is the best stone and most valuable item in the Minecraft game. After all, it can be used to make strong and highly effective tools. Among them are the following:

For example, only with the help of a diamond pick can you get obsidian, which is used for a portal to the underworld. In addition, powerful armor is crafted from a diamond, which means that the player will prevail over evil mobs.

Diamond has been used by humans for over two hundred years. Previously, only jewelry was made from this mineral, but now it is widely used in various industries.

Diamond known primarily for its hardness: on the Mohs scale, it is determined by ten points, which is the highest possible score. And to give a diamond a cut is possible only with the help of another diamond, since no other substance is capable of breaking its strength.

What is made of diamonds?

The two main characteristics of diamond, such as aesthetics (beauty) and unique strength, create two main uses for this mineral by humans.

The diamond has found application in the following industries:

• Jewelry. Most people know what the cut diamond is called. It is made of diamond, giving it a special cut. Diamonds come in different sizes, colors and shapes. They are inserted into rings, earrings, pendants, bracelets and other jewelry in a wide variety of styles. The high cost of such jewelry is explained by the high level of monopolization of this market. Thus, half of the world's diamond production falls on the De Beers firm. Diamond deposits are located in Africa, Namibia, Botswana and Tanzania.
• Production of drills, cutters, saws, scissors and knives. On the basis of diamond, due to its exceptional hardness, the production of various instruments, including surgical ones, has been established. The diamond component provides the ability to model the smallest details of the tools, while keeping them extremely robust.
• In industry, not only pure minerals are widely used, but also diamond powder. It, in turn, is mined in two ways: as a waste in the processing of natural diamonds, and by artificial synthesis. Abrasive substances, grinding wheels, cutting tools, etc. are made from diamond powder.
• Diamond has found its application in the field of microelectronics due to thermal conductivity and high breakdown voltage.
• The mineral is used in quantum computers.
• In the nuclear industry.
• In the watch industry.
• Semiconductor devices are made on the basis of diamond(using doped diamond films).

What are diamonds used for?

The name of this mineral can be translated as "hardest" (al-mas) from Arabic or "indestructible" (adamas) from Greek.

Despite the fact that people have long known the unsurpassed hardness of this substance, until the end of the 20th century it was used mainly as a decoration. Jewelers distinguish more than 1000 types of this stone, dividing it by color, saturation of color, degree of transparency, presence of cracks, etc.

At the moment, the diamond potential of developed countries has a strong impact on the economy. Diamond is used in the processing of a wide variety of materials, is used in the field of rock drilling, in the wire drawing process, is widely known for its sharpening properties. Its hardness is 150 times that of hardness.

Substances such as are subjected to diamond processing:

• Non-ferrous metals;
• Black metals;
• Glass;
• Plastic;
• Hard alloys;
• Rubber;
• Various synthetic substances.

This technique has several advantages over other types of processing:

1. The quality of manufactured products is greatly improved
2. Labor productivity increases tens and hundreds of times
3. The service life of the manufactured parts is greatly extended due to perfect grinding and the absence of microcracks.

Diamond powders

Deserves special attention diamond powder which is widely applied in many industries.

Thanks to such powders, for the first time, it was possible to design special drills that allow you to make the finest holes in very fragile materials, as well as work effectively with hard surfaces. this powder is widely used in lapidary factories.

Thanks to him, dull and nondescript stones turn out to be sparkling and bright.

Diamond as a radiation detector

The charged particles produce a special flash in the diamond, resulting in a current pulse. Due to this property, this mineral can serve as a nuclear radiation detector and be used as a counter of fast particles.

Such a counter is many times superior in its qualities to gas counterparts and other crystal devices.

How are diamonds processed?

How is a diamond cut? This mineral is served by grinding, polishing and cutting only with the help of the same diamond. The discovery took place in India, when one of the jewelers noticed that if you rub one stone against another, the brilliance of both becomes much more pronounced.

But the secret of how diamonds are polished, as well as the art of stone cutting, was kept secret for a long time. The first European who managed to cut a diamond was a master Ludwig Berkem.

Another way to cut diamonds is sawing... People learned to saw this mineral much later than making diamonds.

Previously, special steel wire was used for this, but the process was very long: sometimes it took years. Today, cutting diamonds is much easier. To do this, use the finest bronze cutters with a special emulsion, which includes diamond dust.

Diamond cost

There is a whole science involved in calculating the value of diamonds. depends on its rarity, which, in turn, also has a number of criteria.

For example, the cleaner the stone and the greater its specific gravity, the less often it can be found in nature. To make a gem-quality diamond with a value of one carat, an average of 260 tons of ore must be processed.

But the final price of a diamond depends not so much on mining costs as on the state of the market at a certain moment. There are also more specific criteria: for example, an uncut stone will have a value 2 times less than a cut diamond. This is due to the fact that the high discount of the finished diamond covers all costs and risks in the processing process.

There are 4 generally accepted indicators that affect the price of a diamond:

• Cut.
• Color (in essence, its absence).

Thus, when calculating the cost of one carat, all of the above factors are taken into account, as well as the ratio of supply and demand. The second is the most important criterion for determining the price of a diamond.

In addition, there is a specific analysis of each stone and more narrow classifications of diamonds.

What does a diamond look like?

Answering the question, what does a diamond look like in nature, we can safely admit that it is rather unattractive. The stone has a rough surface, faded color and is often covered with a grayish crust with cracks. A diamond from a diamond is made only by careful and high-quality cutting of the stone, which includes many stages.

Scientifically speaking, a diamond is considered a mineral that has the shape allotropic cubic carbon.

The diamond has the following features:

• Dispersion.
• The ability to conduct heat.
• Highest level of hardness.
• High degree of refraction.
• Low air friction against metal.
• Highest abrasion resistance.
• Highest elasticity compared to other minerals.
• Lowest compression ratio.
• Luminescence. As a result of exposure to ultraviolet, X-ray and cathode rays, the diamond glows in different colors and casts glare.
• In addition, diamond has unique dielectric properties.

How to recognize fake diamonds?

Sometimes it is extremely difficult to distinguish a real diamond from a fake, and only a real expert can do it.

However, there are a number of ways to help identify a fake:

Thus, distinguishing a real diamond from a fake is rather difficult, but using a number of tricks, it is still possible.