Method of forming diamond-structured particles

FIELD: carbon particles.

SUBSTANCE: invention relates to technology of preparing particles having monocrystalline diamond structure via growing from vapor phase under plasma conditions. Method comprises step ensuring functioning of plasma chamber containing chemically active gas and at least one carbon compound and formation of reactive plasma, which initiate appearance of seed particles in the plasma chamber. These particles ensure multidirectional growing of diamond-structured carbon thereon so that particles containing growing diamond are formed. Functioning of plasma chamber proceeds under imponderability conditions but can also proceed under gravitation conditions. In latter case, seed particles and/or diamond-containing particles in reactive plasma are supported under effect of external gravitation-compensating forces, in particular by thermophoretic and/or optic forces. Temperature of electrons in the plasma are lowered by effecting control within the range from 0.09 to 3 ev. Chamber incorporates plasma generator to generate plasma with reduced electron temperature and device for controlling forces to compensate gravitation and to allow particles to levitate in the plasma with reduced electron temperature. This device comprises at least one levitation electrode for thermophoretic levitation of particles in plasma with reduced electron temperature or an optical forceps device.

EFFECT: enabled efficient growing of high-purity duly shaped particles with monocrystalline diamond structure having sizes from 50 μm to cm range (for instance, 3 cm).

19 cl, 5 dwg

 

This invention relates to a method of obtaining particles having a single crystal structure of diamond, and more specifically to a method of growing from the vapor phase of diamond particles in the plasma conditions.

Chemical vapour deposition (CVD) using plasma is widely known from the prior art. Ways CVD deposition of carbon with a diamond structure are investigated for several years. .Ishikawa et al. describe the synthesis of diamond by plasma in microgravity, using the plasma chamber, which is schematically shown in figure 4 (M.Ishikawa et al. in SPIE conference on materials research in low gravity II", SPIE vol. 3792, July 1990, pp.283-291 and "Adv. Space Res.", vol. 24, 1999, pp.1219-1223). Plasma chamber 100′ contains a substrate 10′, the anode 20′ and the cathode 30′. The distance of 21′ between anode and cathode is equal to 1, see Plasma chamber operates in constant current mode under high pressure (approximately 5·103PA). If the camera serves a mixture ofH2and CH4it is possible to grow the carbon structure of the diamond on the substrate 10′ by the production method of vapor phase.

Traditional methods of deposition of diamond have many drawbacks, which limit the practical applicability of diamonds obtained by deposition. A significant drawback is the limitation on the formation of thin film formation. The growth rate of diamond is extraordinary what about the low. The structure of the diamond grows only in one direction. Traditional methods could only demonstrate the appearance of diamond on the substrate. However, the thickness of the layers is in the range below 100 nm. In addition, the layers have only a polycrystalline structure. The efficiency of growth of diamond in addition limited the use of relatively small substrate area of approximately 20 mm2. The method according to the prior art does not allow to influence the form or composition of the layers of carbon.

Forming a layer of diamond by plasma based in particular on the provision of electrons with a low electron temperature. Electronic temperature is a parameter that describes the distribution of the average energy of the electrons. According M.Ishikawa et al. the electronic temperature is reduced in microgravity. Method of regulating electronic temperature described K.Kato et al. in "Appl. Phys. Lett.", vol. 65, 1994, pp.816-818, "Appl. Phys. Lett.", vol. 76, 2000, pp.547-549.

The method described K.Kato, carried out with a device that is schematically shown in figure 5. The device 40′ to gain electrons with low temperature (hereinafter: the source of cold electrons 40′) contains the source 41′ plasma, surrounded by a wall 42′ camera and the grid 43′ grounding. Changing negative potential DC, when ledyaeva to the grid 43′ the electron temperature can be reduced in size by almost two orders of magnitude. The formation of the plasma is performed by the source 41′ plasma in region I surrounded by a wall 42′ camera and the grid 43′. High-energy electrons in the plasma can pass through the grid in a different area II. Ionization is due to the electrons in this region II, leading to the formation of cold electrons, which are not responsible for maintaining discharge source 41′ plasma. According to the specified procedure could be obtained electron temperature in the range from 0.035 eV to 3 eV, for example, and 0.09 eV. The content of the above publications K.Kato et al., in particular in relation to the operational parameters control the electron temperature shown in the present patent application by reference.

The first aspect of the present invention is to provide an improved method of forming particles having (mostly) single-crystal structure of diamond, with this method in particular provides grown from the vapor phase single-crystal structure of diamond with high effectiveness, purity and form. An additional aspect of this invention relates to a method of forming a compact, three-dimensional particles of diamond. The second aspect of the invention relates to the formation of new frequent the C, having a single crystal structure of diamond, these particles are in particular preset purity, composition and/or shape.

These objectives are solved by a method, particles or plasma chamber having distinctive features according to claim 1, 2 or 19. The predominant variants of the invention are defined in dependent claims.

According to the invention, at least one particle having a single crystal structure of the diamond formed by a multidirectional growth of carbon from the vapor phase with a diamond structure or a tetragonal structure in the reactive plasma. Due to the multidirectional growth of carbon from the vapor phase, the structure size of the diamond increases simultaneously in all directions in space. Starting with the seed particles, the structure of the diamond is grown in three directions. Growing the diamond particles are arranged in space in the reactive plasma. Particles trapped in space under the influence of external forces, compensating gravity. Forces that support particles are contactless, so that the entire surface or at least almost the entire surface of each particle acts reactive plasma and the entire surface is subjected to a process of growth from the vapor phase. These conditions according to this invention provide the t significant advantage of efficient growth process, to form particles having a shape almost to the cm-range. Unlike conventional methods, layer-by-layer deposition of polycrystalline monocrystalline particle grows extensively on all surfaces, i.e. with a higher growth rate. The result of the impact forces, compensating gravity, the growth process can be maintained even in the case of particles with masses from ng to mg range.

According to a preferred variant of the invention, the particles are grown in microgravity or zero gravity. Such conditions obtain in the plasma chamber, which is located on the orbit, for example, space vehicles like the international space station (ISS), or satellite. In this situation, all of the Luggage and its contents are subjected to centrifugal forces that are external forces that compensate for gravity. The condition of microgravity occurs when gravity is lower than 10-3g, for example, 10-4g. This option has two significant advantages. First, the forces that compensate for gravity, are an integral, if the method according to the invention, carried out in orbit. Additional measures to support the growing particles are not required. In this case, you can use conventional plasma chamber. Secondly, the authors of this image is the shadow found especially good results are obtained when the growth of diamond particles from the vapor phase is carried out in a plasma containing low-temperature electrons. According to the results .Ishikawa (see above), the electron temperature decrease get in microgravity or zero gravity. If method according to the invention carried out in orbit, additional measures to reduce the electron temperature can be avoided.

According to other preferred variants of the invention, the particles with the structure of the diamond get in gravity conditions, the external force compensating gravity, include, for example, thermophoretically forces, mechanical forces, optical forces and/or electrostatic forces. The authors of this invention have the ability of maintaining the growing particles in the reactive plasma, while the particle surface remains free or almost free. This variant of the invention has a special advantage in relation to the implementation in terms of gravity. The plasma chamber can be operated stationary on the Earth's surface.

The formation of particles having a single crystal structure of the diamond according to the invention allows to obtain different types of particles. In General, the particle having a single crystal structure of diamond, is an object that is covered in all directions is the third in the space of the layer of diamond. The object may be composed entirely of carbon. Alternatively, the object may contain a nucleus, which was used as the seed particles and which contains other material other than carbon. The core may be of a size which is much smaller than the size of the growing particles. Alternatively, the core may have a size that is comparable with the size of the growing particles. In the latter case, the invention features a composite particle with non-carbon media and the structure of the diamond, besieged from all sides on all surfaces of the media.

Preferably the method according to the invention, is carried out in a reactive plasma with low electron. This feature is of considerable advantage in the aspect of purity of the obtained particles of diamond. The inventors have found that the chemical linkage that forms the structure of the diamond, can be obtained with high fertility. Preferably, the temperature of the electrons adjust in the range from 0.09 eV to 3 eV.

According to other preferred features of the invention the method is carried out in a heated plasma chamber. The method according to the invention includes a thermal control. According to a variant of the invention, moreover, increased purity and reproduction the growth of the particles. Preferably the temperature is ur plasma and growing particles adjusted in the range from 700° C to 1000°C.

Another object of the invention is a particle having such a structure of the diamond. Particles according to the invention have a diameter equal to at least 10 μm, preferably at least 100 μm. According to preferred variants of the invention, the particles containing the diamond may have a predefined shape and/or composition. A significant advantage of the invention is the possibility of obtaining the so-called adapted or designed diamonds. Of the diamond structure formed according to the invention, are characterized by extremely high purity, which has been proven through the implementation of Raman spectroscopy.

Another object of the invention is a plasma chamber adapted to implement the above method of forming particles having, at least partially monocrystalline structure of the diamond. Plasma chamber according to the invention, in particular, contains a plasma generator with a grid to ensure low-temperature electrons, and a device for controlling forces for the application of external forces, compensating gravity.

In addition, the invention has the following advantages. The method of formation of diamond particles may be made by any available means of production of plasma (in particular, an RF plasma is s, plasma at a constant current, inductive and/or capacitive coupled plasma magnetron plasma, microwave plasma, arc plasma). The state of plasma can be obtained in a wide pressure range, covering the methods available from a low-pressure plasma to plasma high-pressure (approximately 10-1up to 10,000 PA). There are no particular restrictions on the reaction gases. The invention can be implemented using any gas containing carbon. Particles can be grown with a significantly increased growth rate, about 1 μm/HR or more. In contrast to the layers of the diamond, known for their level of technology, which had polycrystalline structure of the diamond particles according to this invention have a single crystalline structure of diamond. This may be the single crystals with dimensions of at least 10 microns.

Further details and advantages of the invention are described with reference to the accompanying drawings. In the drawings shown:

Figure 1: schematic diagram of the plasma chamber used for implementing the method according to the claimed invention.

2, 3: depicts the variations of the plasma chambers with electrodes levitation,

Figure 4: schematic illustration of a conventional plasma chamber, and

Figure 5: is an illustration of a source of cold electrons.

<> According to the invention, the diamond particles formed in the plasma chamber 100, which is schematically depicted in figure 1. Plasma chamber 100 comprises a generator 40 plasma electrodes 20, 30 (see below), the grid 43 for regulating the temperature of the electrons, the device 50 for regulating forces for the application of external forces, compensating gravity, and a device for temperature control 60 for regulating the temperature of the plasma chamber 100. These components are installed in the housing 42, which has, for example, a cylindrical shape. In the plasma chamber 100 is installed generator 40 plasma and the grid 43 to obtain a reactive plasma. Plasma chamber 100 is divided into two regions, I and II, the grid 43. In region II is generated plasma with cold electrons as described above in relation to sources of cold electrons from the prior art. The growth of diamond particles 10 (shown schematically) from the vapor phase is carried out in region II, as described below. Growing particles can be observed and analyzed using the appropriate measuring device through the window 44 of the observation.

It should be noted that the components 50 and 60 represent the elements of the plasma chamber 100, which is not necessarily installed. The device 50 to control forces can be avoided if plasma chamber 100 is operated in conditions of microgravity the AI and zero gravity. Device for temperature control 60 can be excluded, if the ambient temperature of the plasma chamber 100 is high enough to obtain particles with the structure of the diamond.

The device 50 for regulating forces contains, for example, the electrode 51 levitation (see figure 2, 3), the feeder gas, the device optical tweezers or electrode device for providing electrostatic forces. The levitation electrode set for thermophoretically levitation of particles. Thermopanes has the advantage associated with the relatively simple structure of the device for controlling forces. In addition, the levitation electrodes can optionally be used as a temperature controller. Levitation of particles using a device for supplying gas to compensate for gravity flow of gas. The above-mentioned technique using a gas stream mainly known on the basis of other applications in the vapor deposition. Levitation of particles can be adjusted with high accuracy. The use of optical tweezers or electrostatic devices makes it possible to adjust the position of the individual particles. In particular, using optical tweezers single particle can be moved in the plasma.

Plasma chamber 100 includes additional components for supplying the reaction gases, pressure regulating, to tawki seed particles and extraction of diamond particles from the chamber. These components are provided as devices for control and manipulation, which are known as such from normal plasma and vacuum technology.

Figure 2 and 3 depicts the plasma chamber 100. The generator 40 plasma contains plasma electrodes 20, 30. The plasma electrode 20 has a cylindrical shape, surrounding the area of the I generate a plasma. Plasma electrode 30 is a plate-like electrode with an outer diameter that overlaps the diameter of the cylindrical plasma electrode 20. Both electrodes are made of suitable inert material such as stainless steel. The diameter of the plasma electrode 20 is approximately 10 cm Height of the plasma electrode 20 along the axis is approximately 5 see the Size of the plasma chamber 100 or its components as a rule, you can choose like the size of normal plasma cells. However, the plasma chamber according to the invention may have other dimensions depending on the application.

While the area of the I is limited to one side of the plasma electrode 30, the other side is covered with a grid 43 for regulating the temperature of the electrons. The netting is made, for example, from stainless steel with a mesh size of 0.1-1.2 cells/mm Mesh 43 has a negative potential of the DC so that it functions as a filter for electrons, dormancy is giving the region I.

The plasma electrodes 20 and 30 can be used to produce radio-frequency plasma. Cylindrical plasma electrode 20 may be a radio-frequency electrode (see figure 2) or a grounded electrode (see figure 3), whereas the other electrode 30 is a counter-electrode. The details of the process of generation of plasma is not described in this description, because they are essentially known from the prior art.

The electrode 51 levitation set from the grid 43 at a distance along an axis approximately equal to 5 cm Electrode 51 is made in the form of a plate or grid, which is heated for forming thermoforming flow inside region II. The temperature of the electrode 51 levitation correct use of the device 52 of the control.

Preferably the method according to this invention is carried out by following the below steps. First, the plasma chamber 100 operates in accordance with the prior art in the field of plasma technology. Reactive gas is fed into the plasma chamber. Reactive gas contains, for example, a mixture of N2and CH4. Preferably, the content of CH4choose from 1 to 10%. Other possible mixtures of chemically active gas represent CH3HE2H5HE2H2, CO2WITH. The pressure of the reactive gas is adjusted in the range of 10 Torr to 100 PA. In gravity conditions preferred mode of low pressure. In addition, the temperature of the plasma chamber 100 is adjusted in the range 700aboutWith up to 1000aboutC. regulate the Temperature using the device for regulating the temperature of 60 electrically.

Secondly, the seed particles injected into the plasma chamber 100, in particular in the region II-containing plasma with cold electrons. Mainly the formation of seed particles can be performed according to one of the following methods. In the case of "growth " in situ" the seed particles are formed spontaneously in the plasma. The density of the spontaneous formation of seed particles can be adjusted. Alternatively, the seed particles is served outside in the plasma chamber. Such filing of the seed particles is preferable if the method according to the invention is carried out in a gravity conditions. As the seed particles serves microscopic diamond particles, conductive particles or conductive particles. The use of diamond particles is of particular advantage, providing the lattice structure of the substrate, which needs to grow. Non-conductive particles (for example, ceramic particles or conductive metal particles (e.g., Ni) have the advantage associated with improved control of levitation, in addition, they can be given some form or the minimum level so that in order to affect the shape or size of the growing structure of the diamond.

Next, carry out the cultivation of carbon from the reactive gas in many directions on the seed particles. Carbon is deposited on all sides on all surfaces of the particles. During the growth process increases the mass of the particles. In conventional methods can be particles with undesirable distortion. These particles can grow to the size of approximately 40 microns. Larger particles fall under gravity. In contrast to these effects, the invention provides growth of particles in the range of 50 μm and above, for example, from 100 μm up to the cm-range. In microgravity or zero gravity you can get the size of the particles, for example, 3 see

The method according to the invention can be modified in the following way. According to a variant of the invention the form of diamond particles govern by providing seed particles with a predetermined shape, and/or by adjusting the conditions of the plasma in the growth process. As an example, using the seed particles are filamentous form or in the form of a loop. In addition, the plasma chamber 100 may be provided with additional electrodes for regulating the plasma. These electrodes can be adapted to generate an electrostatic or magnetic fields, in particular in the region II, for forming the preferred growth direction.

The composition of the diamond particles can be adjusted by the introduction of additional substances. During the growth process, you can add a dopant to obtain specific characteristics of diamond particles, such as, for example, the color or other optical properties. Alloying impurities are, for example, dyes or metals. Dopant may be added in the form of a beam of molecules or atoms, or alternatively in the form of a powder. The resulting compositions are of particular advantage, possessing the properties of diamond, as well as dopant, which offers a new dimension in the development of functional materials.

The placement of the generator 40 plasma and the grid 43 in the plasma chamber 100 can be modified depending on the specific operating conditions. In microgravity or zero gravity plasma chamber can be positioned in any direction in space. In terms of the gravity of the plasma generator can be placed on the side or at the bottom of the plasma chamber. The control unit forces may contain a mechanical holder for the seed particles and the growing of diamond particles. Mechanical holder contains, for example, strings or wires that are anchored in the plasma chamber. The ends of the threads are in the region of the plasma is low electron temperature. In this situation, the possible growth of the diamond structure on the free surface particles. The diameter of the thread is, for example, 1-2 μm.

1. A method of obtaining particles having the structure of a single crystal diamond comprising the steps under which ensure the functioning of the plasma chamber (100)containing a reactive gas, at least one carbon compound, and the formation of reactive plasma; provide seed particles specified in the plasma chamber (100); provide multidirectional growth of carbon with a diamond structure on the specified seed particles, so that particles are formed, containing the growing diamond, characterized in that the operation of the plasma chamber (100) is carried out in conditions of weightlessness.

2. A method of obtaining particles having the structure of a single crystal diamond comprising the steps under which ensure the functioning of the plasma chamber (100)containing a reactive gas, at least one carbon compound, and the formation of reactive plasma, and the functioning of the abovementioned plasma chamber (100) is carried out under the action of gravity; provide seed particles specified in the plasma chamber (100), which are under the influence of external forces, compensating for the force of gravity in reactive p is the AZM; and provide a multidirectional growth of carbon with a diamond structure on the specified seed particles, so that particles are formed, containing the growing diamond, characterized in that the said seed particles and/or containing diamond particles are held in the reactive plasma by thermophoretically forces and/or optical forces, and temperature of the electrons in this plasma reduced by regulation in the range from 0.09 to 3 eV.

3. The method according to claim 1, in which these seed particles are formed in a specified reactive plasma or served outside.

4. The method according to claim 3, in which these seed particles consist of non-carbon substances.

5. The method according to claim 4, in which these containing diamond particles are combined particles with a carrier coated monocrystalline layer of diamond.

6. The method according to claim 1, in which the pressure of the reactive gas is adjusted in the range from 10-3up to 1 Torr.

7. The method according to claim 1, in which the temperature specified in the plasma chamber govern in the range from 700 to 1000°C.

8. The method according to claim 1, wherein during the growth of these containing diamond particles in reactive plasma is injected, at least one alloying impurity.

9. The method according to claim 1, in which the said particles containing diamond, grow to larger than 50 μm, up to the cm-range.

10. the procedure according to claim 9, in which the said particles containing diamond, grow to larger than 100 μm, up to the cm-range.

11. The method according to claim 2, in which these seed particles are formed in a specified reactive plasma or served outside.

12. The method according to claim 11, in which these seed particles consist of non-carbon substances.

13. The method according to item 12, in which these containing diamond particles are combined particles with a carrier coated monocrystalline layer of diamond.

14. The method according to claim 2, in which the pressure of the reactive gas govern in the range from 10-3up to 1 Torr.

15. The method according to claim 2, in which the temperature specified in the plasma chamber govern in the range from 700 to 1000°C.

16. The method according to claim 2, in which the growth process of these containing diamond particles in reactive plasma is injected, at least one alloying impurity.

17. The method according to claim 2, in which the said particles containing diamond, grow to larger than 50 μm, up to the cm-range.

18. The method according to 17, in which the said particles containing diamond, grow to larger than 100 μm, up to the cm-range.

19. Plasma chamber, adapted to obtain particles having a single crystal structure of diamond, with the specified plasma chamber comprises a generator (40) plasma to generate reactive plasma; edu (43) for generating plasma with low electron temperature; and a device for controlling forces (50) to ensure the strength of the compensating action of gravity, allowing the particles to levitate in the specified plasma with low electron temperature, characterized in that said device for regulating forces (50) includes at least one electrode (51) levitation for thermophoretically levitation of particles in said plasma with a low electron temperature or the device optical tweezers.



 

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FIELD: production of synthetic diamonds, which may be used as windows in high power lasers or as anvils in high pressure devices.

SUBSTANCE: device for forming a diamond in precipitation chamber contains heat-draining holder for holding a diamond and ensuring thermal contact with side surface of diamond, adjacent to the side of growth surface of diamond, non-contact temperature measurement device, positioned with possible measurement of diamond temperature from edge to edge of growth surface of diamond, and main device for controlling technological process for producing temperature measurement from non-contact device for measuring temperature and controlling temperature of growth surface in such a way, that all temperature gradients from edge to edge of growth surface are less than 20°C. A structure of sample holder for forming a diamond is also included. Method for forming a diamond includes placing a diamond in the holder in such a way, that thermal contact is realized with side surface of diamond, adjacent to growth surface side of diamond, measurement of temperature of growth surface of diamond, with the goal of realization of temperature measurements, control of growth surface temperature on basis of temperature measurements and growth of monocrystalline diamond by means of microwave plasma chemical precipitation from steam phase on growth surface, under which the speed of diamond growth exceeds 1 micrometer per hour.

EFFECT: possible production of sufficiently large high quality monocrystalline diamond with high growth speed.

7 cl, 1 tbl, 7 dwg

FIELD: chemical industry; cutting tool industry; mechanical engineering; methods of the production of the artificial highly rigid materials.

SUBSTANCE: the invention is pertaining to production of the artificial highly rigid materials, in particular, diamonds, and may be used in chemical industry; cutting tool industry; mechanical engineering, boring engineering. The method provides for compaction of the powdery carbon-containing materials in the field of the quasi-equilibrium state of the graphite-diamond system and the slow refrigeration in the zone of the thermodynamic stability of the diamond or other synthesized material. The heated capsule made out of tungsten with the pure carbon raw fill in with the liquid silicon at the temperature of 1750°K, hermetically plug up, then reduce the temperature to 1700°K during 30-40 minutes and cool to the room temperature within 5-6 hours in the process of the synthesis of the high-strength materials. The monocrystals of the boron carbide of the 400-450 microns fraction and the diamonds of the 40 microns fraction have been produced. The technical result of the invention consists in improvement of the quality, the increased sizes of the monocrystals, and also in the decreased labor input of the production process.

EFFECT: the invention ensures the improved quality and the increased sizes of the produced monocrystals, the decreased labor input of the production process.

2 cl, 2 ex

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EFFECT: possibility of keeping diamond intact during treatment.

46 cl, 4 dwg, 1 ex

FIELD: treatment of diamonds.

SUBSTANCE: proposed method includes the following stages: (i) forming of reaction mass at presence of diamond in pressure-transmitting medium fully surrounding the diamond and (ii) action of reaction mass by high temperature and pressure during required period of time; diamond is of IIb type and its color is changed from gray to blue or dark blue or is enriched by action on reaction mass of temperature from 1800°C to 2600°C at pressure of from 6.7 GPa to 9 GPa (first version). Diamond of type II may be also proposed which contains boron and its color is changed to blue or dark blue by action on reaction mass by the same temperature and pressure (second version).

EFFECT: improved color of diamond by changing it from gray (brown-gray) to blue or dark blue.

31 cl, 4 dwg, 2 ex

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30 cl, 4 dwg, 1 ex

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36 cl, 10 dwg, 1 tbl, 4 ex

FIELD: production of diamonds of jewelry property; high-quality cleaning of diamonds.

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