Coloured diamonds

FIELD: technological process.

SUBSTANCE: invention is related to the field of coloured diamonds preparation, which are used, for instance, in decorative purposes. Method of coloured single crystal diamond transformation into different colour includes stages, at which coloured single crystal diamond is prepared by method of chemical depositing from steam phase (CDSP) and prepared diamond is thermally treated at temperature from 1200 to 2500°C and pressure that stabilises diamond, or in inert or stabilising atmosphere. Prepared single crystal may be shaped as thick layer or fragment of layer, which is cut as precious stone.

EFFECT: allows to prepare diamonds with wide range of colour gamma.

61 cl, 8 ex, 5 dwg

 

Background of invention

The invention relates to a method for producing a colored diamond and in particular color monocrystalline diamond, used, for example, for decorative purposes, the method of chemical vapour deposition (CVD).

A diamond with ideal lattice is transparent in the visible spectrum and has its own width of the bandgap of 5.5 eV. The introduction of defects or color centers, as they will be referred to in the present invention further having associated energy levels within the forbidden zone, give the diamond color, which depends on the type and concentration of color centers. This color may be the result of absorption or photoluminescence or some combination of these two processes. One example of a common color centers in synthetic diamond is nitrogen, which, being in a position of substitution in the neutral charge state, has an associated energy level ˜1.7 eV below the conduction band) and in the merger gives the diamond a characteristic yellow/brown color.

It is well known that the chemical composition and processing of diamond, such as irradiation by particles with sufficient energy or radiation (electron, neutron, gamma, and so on), leading to the formation of lattice defects (impurities and vacancies), and meet the speaker subsequent annealing can lead to the formation of color centers, such as a complex of a nitrogen atom - vacancy in the neighboring lattice sites [N-V], which can give the diamond color (see, for example, EP 0615954 A1, EP 0326856 A1 and the links). Characteristics of the color centers and their methods of artificial receipt described in detail in John Walker, Reports on Progress in Physics, Vol.42, 1979. Method of artificial formation of color centers that are described in these messages is that the lattice defects formed by irradiation by an electron beam and for connection of lattice defects with nitrogen atoms contained in the crystal, using annealing. However, due to the competing formation of defects and a strong dependence of the sector growth on the concentration of defects, such as nitrogen in diamond, there are limitations for color and uniformity that can be obtained by this method.

Diamond color obtained by chemical composition and the formation of color centers is the color combination of the raw diamond to postremoval processing effect on the color of one or more color centers, modified or obtained in the process postremoval processing. To obtain the necessary decorative values and the combination of high transparency and the desired color is usually as a source of materials used or colorless or light yellow diamonds. For brown monokristallicheskogo, received by the CVD method, this method does not give the desired results.

Methods of increasing the transparency of polycrystalline diamond obtained by means of CVD using a processing at high pressure and high temperature, which increases the density of diamond is described in EP 671482, US 5672395 and US 5451430.

It is also known that the color brown natural diamond can be changed with annealing at high pressures and temperatures. For example, natural diamond type IIa may be discolored by annealing at very high temperatures and stabilizing the pressure or turn in pink by annealing at slightly lower temperatures and stabilizing the pressure. It is believed that brown natural diamond can be associated with plastic deformation, however, the exact origin of the brown color and how it transforms under the action of annealing, is still unknown.

There are three perceived characteristics of color: hue, lightness and saturation. The color tone is characteristic color, which allows us to classify it as red, green, blue, yellow, black or white, or color tone is intermediate between the neighboring pairs or triples of these basic colors.

White, gray and black objects are distinguished on the scale of values from light to dark. Light is but a characteristic color, determined by the degree of similarity neutral achromatic scale that starts with white, passes through the darker gray levels and ends with black.

Saturation indicates the degree of color differences from the achromatic color with the same lightness. It is also the term describing the intensity of the color. In the diamond trade, in order to distinguish different degrees of saturation, assessed visually, using such adjectives as intense, strong, lively, bright. In the color system of the CIE L*a*b* saturation is the degree of removal from the neutral color axis (determined by saturation = [(a*)2+(b*)2]1/2, see below). Lightness is the visual property that is perceived separately from saturation.

Currently, methods of deposition on the substrate materials such as diamond using CVD are well known and described in the patent and other literature. For the deposition of diamond on a substrate commonly used gas mixture, which upon dissociation can form an atomic form of hydrogen or halogen (such as F, Cl) and or carbon-containing radicals and other reactive components, for example, CHx, CFxwhere x can be from 1 to 4. In addition, there may be oxygen-containing components, and components containing nitrogen and boron. The nitrogen which may be introduced in the synthetic plasma in several forms; this is usually N2, NH3, air and N2H4. In many processes there are also inert gases such as helium, neon or argon. Thus, a typical source gas mixture must contain hydrocarbons WithxHywhere x and y each may be from 1 to 10, or kalogeropoulou CxHyHalzwhere x and z each can be from 1 to 10, and y can be from 0 to 10, and optionally one or more components of the series: COxwhere x can be from 0.5 to 2, O2H2N2, NH3In2H6and inert gas. Each of the gases can be used in natural isotopic ratio or isotope ratios can be artificially regulated; for example, hydrogen may be present as deuterium or tritium, and carbon may be present, as12With or13C. Dissociation of the gas mixture is carried out using an energy source, such as microwave, RF (radio frequency), flaming, device-based hot filament or nozzle, and the reaction gas products, thus obtained, is then precipitated onto the substrate with the formation of the diamond.

To obtain diamond CVD method can be used for various substrates. Depending on the nature of the substrate and chemistry of the CVD process can be obtained polycrystalline or monocrystalline diamond.

Summary of the essence of the ti inventions

In accordance with the present invention a method of producing single crystal diamond of the required color is that CVD method are color monocrystalline diamond (color, which he sometimes is necessary) and conduct heat treatment of diamond under conditions that are required to achieve the desired color.

Single-crystal diamond obtained by the CVD method, is used as the source material, colour, and heat treatment is carried out under controlled conditions required to obtain another desired color of the diamond.

In diamond you can often see several colors. The dominant color is the color that the observer chooses under standard conditions of illumination and observation, if it is necessary to find the most accurate description that contains only one color. A diamond with this predominant color, its color can be modified by other flowers that border the predominant color in three-dimensional color space, such as color space CIE L*a*b*, described below. For example, in a three-dimensional color space region of pink flowers bordered by areas of white, gray, brown, orange, purple and red colors. Therefore, a pink diamond in principle can manifest in different degrees of any of these colors as a component of fashion is viceroyship color, and can be described as, for example, grayish-pink, brownish pink or Orangevale pink. In the present description and the claims where there is mention of a different color (e.g., brown diamond, green diamond), referring to the predominant color, and can be the secondary color components, changes color.

Usually diamonds are polished so that, when observed properly, the color on the front side is slightly different from the color that is best seen on the lateral side. This is partly due to the fact that the faces are polished so that when observed properly path length inside the stone of light rays reaching the observer's eye, was significantly increased at the expense of one or more internal reflections. The effect of increased length on the color coordinates can be modeled by the method described below.

Usually as the source material is brown, single crystal diamond produced by the method of CVD. Under appropriate conditions of heat treatment brown color can be converted into one of the necessary colors, including colorless or nearly colorless, and, in particular, fantasy colors. In the trade classification of precious stones, the term "fantasy" refers to the color of the diamond richer and of higher quality. Heat treatment can in order to be such, the result can be a number of fancy green and some fancy pink color of the diamond.

Single-crystal diamond obtained by the CVD method, may be in the form of a layer or portion of a layer, for example, faceted like a jewel. Primarily the invention relates to a thick layer of diamond, which include layers of diamond thickness greater than 1 mm, and the fragments obtained from such layers. In addition, the layer of diamond obtained by the CVD method, preferably has a uniform crystal quality throughout the thickness, so that any desired color is not extinguished or not concealed in any of the zones layer defects associated with low quality of the crystal. For such layers or fragments of these layers, you can get pink and green, in particular fancy pink and fancy green color of this quality, what cannot be obtained from known natural diamond, thermally processed by the known methods or by the known synthetic materials obtained in high pressure high temperature processed by the known methods. In particular, the layer of single crystal diamond produced by the method of CVD, of a thickness exceeding 1 mm, for example, to produce precious stones, in which each of the three orthogonal dimensions greater than 1 mm

It was found that single-crystal diamond, p is obtained by the CVD method, subjected to heat treatment or annealing under the conditions proposed in the present invention has a desired color, which can be defined in terms of the color space CIE L*a*b*. In particular, it was found that a layer thickness of 1 mm with parallel faces, made of single-crystal diamond obtained by the CVD method, after the heat treatment is in the color space CIE L*a*b* coordinate b* in one of the following ranges:

0≤b*≤8

0≤b*≤4

0≤b*≤2

0≤b*≤1

As mentioned above, the heat treatment of single crystal diamond produced by the method of the HOPF bifurcation can lead to the formation of colorless or nearly colorless diamond. Almost colorless diamond can be described in terms of color space CIE L*a*b*. In particular, heat-treated layer with a thickness of 1 mm with parallel faces, made of such a diamond can have saturation (C*), which is less than 10, or less than 5, or less than 2. Thermal treatment may be different depending on the nature of the diamond grown by CVD method, and the color, which should be obtained in diamond. For example, it was found that the thick layers of brown single-crystal diamond obtained by the CVD method, or fragments, cut of these layers may be annealed to receive the deposits required color from pink to green at temperatures from 1600 to 1700° And pressure, stabilizing the diamond, for a period of time, usually 4 hours. What is surprising is that the color of such thick layers of diamond or fragments cut from these layers, can also be changed in color from pink to green by thermal processing layers at temperatures from 1400 to 1600°over time, usually 4 hours, when the pressure in the stable graphite in an inert or stabilizing the atmosphere. Examples of the inert atmosphere is argon (Ar).

In one of the embodiments of the invention, single crystal diamond produced by CVD method in such a way that in the solid diamond is entered from 0.05 to 50 ppm million of nitrogen. The lower limit of this range preferably is 0.1 ppm million, more preferably 0.2 to frequent./million, even more preferably 0.3 to frequent./million Upper limit of this range is preferably 30 ppm million, more preferably 20 ppm million, even more preferably 10 ppm million This result can be obtained using, for example, a plasma process, in which nitrogen is present in the gas phase (initially in the form of N2, NH3or some other nitrogen-containing molecules). To obtain reproducible results and the required end-product of nitrogen in the process you want to monitor. Typically, the concentration of nitrogen in getvoltage (all nitrogen concentration in the gas phase in the present description is based on the N 2equivalent, for example, one molecule of N2equivalent to two molecules of NH3) is 0.5-500 ppm million, more preferably 1-100 ppm million, and even more preferably 2-30 frequent./million, but experts in the art should understand that the nitrogen absorption is very sensitive to such conditions as temperature, pressure, composition of the gas phase, therefore, the scope of the present invention is not limited to the above limits.

Can be used various isotopes of nitrogen, such as14N and15N. the Influence of different isotopes on the chemistry of growth and the final results are in General negligible, except that any defects involving nitrogen, may have their optical band shifted due to the difference in atomic masses. To obtain the data presented in the present description, with the exception of example 8, was used isotope14N, but the scope of the present invention includes all isotopes of nitrogen.

The absorption of such impurities as nitrogen is also sensitive to sector growth, and the final layer is preferably predominantly or substantially entirely by a single growth sector or type of growth sectors that are related by symmetry. Can be used such sector growth, as{100}, {111}, {110}, {111}, more preferably sector growth of {100} and {113} and most predpochtitel what about the {100}. Diamond may also contain low concentrations of other impurities, such as phosphorus, sulfur and boron, although the preferred method eliminates them.

Heat treatment (annealing) is usually conducted in the temperature range of 1200-2500°C. the lower limit of this range, in addition to the equilibrium concentrations of defects exposed to, usually determined by the achievement of acceptable kinetic rates of processes for which produce annealing. The upper limit of this range is determined by practical considerations, which consists in the complexity of the process at high pressure and temperatures above 2500°Since, although the ability of annealing to form, in particular, almost colorless diamonds at a higher temperature increases. The lower limit of this range is preferably 1250°S, more preferably 1300°S, and even more preferably 1400°C. the Upper limit of this range is preferably 2000°S, more preferably 1900°S, and even more preferably 1800°C. the Annealing occurs for a period of time from 3 to 3×106seconds. The lower limit of this interval is preferably 30 seconds, more preferably 100 seconds, and even more preferably 300 seconds. The upper boundary of this interval is preferably 3�D7; 105seconds, more preferably 1×105seconds, even more preferably 2×104seconds and even more preferably 7×103seconds.

The annealing can occur at a pressure stabilizing diamond, or may occur near or below atmospheric pressure, for example, in an inert or stabilizing the atmosphere. Experts in the art should understand that between these variables exists interdependence, longer annealing is usually required at lower temperatures or at the same temperature, but when using a stabilizing pressure. Thus, this temperature range may be more appropriate for the given range of time, and both of these parameters can be different if you use a stabilizing pressure. The upper limit of the annealing temperature without the use of pressure, stabilizing the diamond is 1600°in particular, if the long or annealing process is insufficiently controlled, which is connected with the problem of graphitization. However, annealing at temperatures up to 1800°and in extreme cases up to 1900°can be carried out without pressure, stabilizing the diamond.

For the purposes of the present description of the invention, the pressure range can be divided into two regions: the region of stable diamond, often referred to as the t, stabilizing the diamond, and the region of stable graphite. Most simply reachable area in the region of stable graphite is about atmospheric pressure (1,01×105PA), although in a controlled gas environment in General is quite simple to achieve lower pressures, for example, from 1×102PA to 1×105PA, as well as higher pressures, for example, from 1,02×105PA to 5×105PA. The pressure range below 5×105PA has no significant impact on the annealing of defects within the volume of the diamond. It is known that pressure from 5×105PA to pressure, stabilizing the diamond, do not affect the behavior of the individual defects, which differs from the behavior of defects during annealing at a pressure stabilizing diamond and annealing near atmospheric pressure, although the reaction rate, for example, may change as some smooth function of pressure between these two extremes and, therefore, the balance and interaction between the defects may to some extent be changed. Annealing according to the method proposed in the present invention, in the field of stable graphite usually for simplicity performed at atmospheric pressure, but it does not limit the method of the present invention, which includes annealing and other pressures in the area of stable graphite.

Usually pressure, modulating ishemia in high pressure presses, are kilobar. For consistency, all values of pressure in the present invention are given in PA, a particular magnitude higher pressures are translated in a bar or kbar using the conversion factor 1 bar = 1,0×105PA.

Color crystal diamond obtained by the CVD method in accordance with the present invention, preferably has the required color tone. The angle of this hue is the angle of the line connecting the point representing the color tone in the color chart a*b*, with the origin of coordinates, relative coordinates a*, as shown in figure 4. The angle of the hue of the diamond obtained by the CVD method, after the heat treatment should usually be less than 65°or less than 60°or less than 55°or less than 50°. It is well known that due to the acknowledged beauty and rarity, pink and green diamonds are particularly highly prized by jewelers, collectors and consumers (Pink Diamond, John M. King et al., Gem and gemology. Summer 2002, Collecting and Classifying Coloured Diamonds, Stephen C.Hofer, 1998, Ashland Press Inc. New York). In the General case pink and green crystals are valued higher, purer color and the smaller the influence of the secondary color components that affect color. Conditions of heat treatment or annealing is proposed in the present invention, can increase the purity of color by increasing, at the Alenia, reduction or modification of absorption, which contributes to the color change. At the same time, the annealing or heat treatment can increase the brightness by reducing the concentration of defects, which reduces the absorption over a wide spectral range.

Some of the color centers, which contribute to the color brown diamond obtained by the method of the HOPF bifurcation are unique defects in single-crystal diamond obtained by the CVD method, or slices, cut or made from layers of single-crystal diamond obtained by the CVD method, and may, in particular, to influence the apparent color of thick layers. It is quite clear that these color centers are different from those that affect the natural color of the diamond, because they have absorption bands that are absent in the absorption spectra of natural diamond. It is believed that some of the color centers belong to the strongly localized rupture of the diamond links of single-crystal diamond obtained by the CVD method. Proof of this is the Raman spectrum observed under the action of infrared excitation source (e.g., 785 nm or 1064 nm) on Almazny carbon. Such Raman scattering is not observed for brown natural diamond. The relative intensity of the absorption bands of brown monocrystalline Alma is a, received by the CVD method in the visible region of the spectrum can be modified by annealing, which is accompanied by corresponding changes in the spectrum of Raman scattering. Changes in the absorption spectrum are observed at temperatures much lower than is necessary to change the color of a brown diamond. Significant color changes can be obtained by annealing at atmospheric pressure in an inert atmosphere substantially below the temperature at which the diamond graffitied in the absence of oxygen, for example, at 1600°With or below. This was unexpected, since the transformation of the non-diamond forms of carbon in the diamond usually require treatment in conditions of stable diamond at high pressure and temperature conditions.

Features of the mechanism of growth of diamond by CVD method can give absorption bands in the region of about 350 nm or about 510 nm and the band in the near infrared region, which goes into the red area of the visible colors. The color centers responsible for these bands, have so great influence on the color of the diamond grown by CVD method. They are absent in natural or synthetic diamond, obtained by another method. Precious stones, made of diamond grown by CVD method, may have a desired color, including orange-brown to pinkish-brown is. During heat treatment or annealing of such a diamond, performed under the conditions of the invention, the relative intensity of the absorption bands can be changed, for example, shifted or reduced, or increased, thereby to improve the color. Causes of color change can also be the formation of color centers due to the destruction of the defects existing in the grown diamond, or changes in the charge transfer processes leading to change the prevailing charging status of defects. Thus, the annealing or heat treatment can lead to the formation of combinations of color centers, which cannot be obtained in diamond grown by CVD method, thereby forming a single crystal diamond produced by the method of the HOPF whose color is the result of new combinations of color centers. As is well known to specialists in this field, the position of maximum intensity of such broad bands as 350 nm and 510 nm may slightly vary, but it is not a violation of their identity.

Brief description of drawings

Attached to the description of the drawings shows:

Figure 1 - absorption spectrum in the UV-visible region of the sample of Ex-4 registered before (a) and after (b) annealing at 2400°C for 4 hours under a pressure of approximately 8,0×109PA (80 kbar),

Figure 2 - absorption spectrum in The is-visible region of the sample Ex-5, registered before (a) and after (b) annealing at 1900°C for 4 hours under a pressure of approximately 7,0×109PA (70 kbar),

Figure 3 - absorption spectrum in the UV-visible region of the sample Ex-6 registered before (a) and after (b) annealing at 1600°C for 4 hours under a pressure of approximately 6.5×109PA (65 kbar),

Figure 4 is a graph of the values a* and b* color space CIE L*a*b* of the sample of Ex-6, obtained from the absorption spectra in the UV-visible region registered before (a) and after (b) annealing at 1600°C for 4 hours under a pressure of approximately 6.5×109PA (65 kbar and

Figure 5 is a graph of the values of L* and B* color space CIE L*a*b* of the sample of Ex-6, obtained from the absorption spectrum in the UV-visible region registered before (a) and after (b) annealing at 1600°C for 4 hours under a pressure of approximately 6.5×109PA (65 kbar).

Description of embodiments of the invention

The invention relates to a method of controlled color change the color of the diamond obtained by the CVD method, in a different color by heat treatment carried out in a suitable and controlled conditions. Single-crystal diamond obtained by the CVD method, preferably has the shape of a thick layer or slice, cut or manufactured from such layer. A thick layer of monocrystalline and the MAZ high quality produced using CVD, which preferably lies in the fact that make a diamond substrate having a surface essentially free from crystalline defects, prepare the source gas, hold the dissociation of the source gas with subsequent homoepitaxial growth of diamond on the surface of the crystal is mainly free from defects. Diamond grown by CVD method in such a way, does not contain, in particular, inclusions, typical for diamond, obtained at high pressure and high temperature, in particular for diamond, obtained at high pressure and high temperature, the color of which is not determined by a single nitrogen atoms in the position of substitution.

In the General case, this method is carried out in the presence of nitrogen, which is added in synthetic plasma. Nitrogen creates a diamond brown color centers. Nitrogen adding a controlled way violates the growth of diamond in a degree sufficient to ensure the implementation of color centers, including non-diamond forms of carbon, forming a single-crystal diamond having, as shown by x-ray methods, such as x-ray topography, high quality crystal.

To obtain a thick layer of monocrystalline diamond high quality CVD method, it is important that the growth surface of the diamond are essentially free from cristalli the definition of defects. In this context defects primarily mean dislocations and microcracks, but also include twin boundaries and point defects, which are not associated with impurity atoms N, the low-angle boundary and other extensive disturbance of the crystal lattice. Preferably the substrate is a natural diamond type Ia low double refraction, diamond type IB or diamond type IIa, synthesized at high pressure and high temperature, or single-crystal diamond obtained by the CVD method.

The quality of growth on the substrate, there is not enough free from defects deteriorates rapidly as the layer becomes thicker and the defect structures are multiplied, resulting in overall degradation of the crystal, twinning and re-nucleation.

The defect density is most easily defined using optical evaluation after plasma or chemical etching used for detection of defects using, for example, a short laser etching as described below. Can be found two types of defects:

1) the Defects inherent to the substrate material. In a separate natural diamonds density of these defects can be up to 50/mm2more typical values are 102/mm2while in other samples the density can be 106/mm2 or higher.

2) Defects resulting from polishing, including dislocation structures and cracks, forming a wavy track along the lines of polishing. The density of such defects may vary considerably in the sample, the most typical values are in the range from approximately 102/mm2up to 104/mm2and more for poorly polished sections and samples.

The defect density should be such that the density of the signs of etching of the surface resulting from the defects described above, it is preferable was less than 5×103/mm2and more preferably less than 102/mm2.

Defective level on the surface of the substrate on which the growth of diamond by CVD, and below the surface can be minimized with proper preparation of the substrate. Here, under preparation, we mean any process applied to the material extracted from the Deposit (in the case of natural diamond) or synthesized (in the case of synthetic material), since each stage can affect the density of defects within the material plane, which ultimately forms the surface of the substrate, when the preparation of the substrate is completed. A separate stage of processing may include the usual diamond processes, such as mechanical cut the e and Stripping, grinding and polishing (in this application is specially optimized to achieve low defect levels) and less traditional methods such as laser processing or ion implantation and methods of exfoliation, chemical/mechanical polishing and both liquid and plasma chemical processing methods. In addition, RQsurface (standard deviation of surface profile from the plane, as measured by supalogo Profiler preferably within 0.08 mm of length) should be minimized, in that the characteristic values to any plasma etching is not more than a few nanometers, less than 10 nm.

One way of minimizing damage to the surface of the substrate is conducting plasma etching of the surface, which must occur homoepitaxially growth of diamond, in situ. In principle there is no need for etching either in situ or immediately before the growth process, but the greatest efficiency etching is achieved, if it is carried out in situ, as there is no risk of additional physical damage and chemical contamination. Etching in situ is usually the most appropriate in cases where the growth process is a plasma. During plasma etching can be used the same in the conditions, when the deposition or growth process of diamond, but it is carried out in the absence of any carbon-containing source gas and usually at slightly lower temperatures for better control of the etching rates. For example, it may consist of one or more of the following types of etching:

(I) oxygen etching, in which predominantly use hydrogen with a small amount of Ar (by choice) and required a small amount of O2. Typical conditions oxygen etching of the following: a pressure of from 50 to 450×102PA, the oxygen content of etching gas from 1 to 4%, argon from 0 to 30% and the rest of the hydrogen, all the interest volume, the temperature of the substrate 600 to 1100°With (more typically 800°C)the normal duration from 3 to 60 minutes,

(II) hydrogen etching, which is carried out as described in (I), except that oxygen is absent,

(III) alternative methods of etching based on the use not only of argon, hydrogen and oxygen, but also, for example, Halogens and other inert gases or nitrogen.

Typically, the etching consists of oxygen etching, followed by hydrogen etching and then immediately synthesis with the introduction of the carbon source gas. The ratio of time/temperature etching is chosen such as to ensure the removal from the top of the spine damage remaining after processing, and surface contaminants, but not to prevent the formation of a strongly rough surfaces without etching too extended defects such as dislocations, which can cover the surface and thus lead to the formation of deep trenches. Because the etching is a very aggressive process, this stage is particularly important that the chamber design and materials of its components were such that the material has not been translated plasma in the gas phase or on the surface of the substrate. Less specific to crystalline defects of the hydrogen etching, followed by oxygen etching, rounds angular projection formed by oxygen etching, which largely affects such defects, as a result, the surface for the subsequent growth becomes more smooth.

The surface or the substrate surface of the diamond, which is the growth of diamond by CVD method, preferably is a surface{100}, {110}, {113} or {111}. Due to deformations in the processing of the actual orientation of the sample surface may differ from these ideal orientation up to 5°and, in some cases up to 10°although this is undesirable because it adversely affects reproducibility. Also for the method of the present invention is very VA is but careful control of the content of impurities in the medium, where is the growth of the CVD method. It is important that the growth of diamond was in the atmosphere, in which essentially no components that differ from the specially added nitrogen or other additives. The accuracy of measuring the concentration of nitrogen in the gas phase should be not more than 500 ppm billion (molar proportion of the total gas volume) or 5% from the target concentration in the gas phase, and selects the value that is greater than, preferably not more than 300 ppm billion (molar proportion of the total gas volume) or 3% from the target concentration in the gas phase, and selects the value that more, and more preferably not more than 100 ppm billion (molar proportion of the total gas volume) or 1% of the target concentration in the gas phase, and selects the value that is greater. Measurement of absolute and relative concentration of nitrogen in the gas phase at 100 ppm billion requires an appropriate measuring equipment, such as gas chromatography. An example of this method is described below.

The standard method of gas chromatography (GC) measurement is as follows: gas flow sample is withdrawn from a point which needs to be analyzed using sampling tube with a narrow diameter for maximum flow rate and minimum dead volume, is passed through the metering GC loop, p is after which shed. Dosing GH loop is a spiral of tubing with a fixed and known volume (usually 1 cm3for standard input samples at atmospheric pressure), which can be switched out of the line with a break in the gas line carrier (Not high purity), served in the gas chromatographic column. With this switch the gas sample with a known volume falls in the gas stream entering the column in the GC this process is called the input samples.

Put the sample in the flow of carrier gas passes through the first GC (filled with molecular sieves, providing separation of simple inorganic gases), where partially separated, since a high concentration of major gases (e.g., N2, Ar) causes saturation of the column, which makes complete separation, for example, nitrogen. From the first column to the second column, enter only the portion of the eluent, which must be analyzed, thus prevents the other gases in the second column, prevents the saturation of the column and reach the complete separation of the target gas (N2).

The gas stream from the second column enters the detector ionization in the discharge (DIR), which records the change of the current in the ionization chamber of the detector in the presence of the sample. Component identification is made by retention time, which is determined using a standard gas mixture. The linear range DEERE covers five orders of magnitude of concentration for calibration of the detector using special calibration gas mixtures-defined components, usually with a concentration of from 10 to 100 ppm million made by the gravimetric method and certified supplier. The linearity of the DEER can be tested experimentally using a dilute gas mixtures. Samples with target nitrogen, in addition to newly added components (e.g., N2, NH3may contain atmospheric N2and other nitrogen-containing components, which may affect the measurement results.

Known GC techniques have been modified and adapted for the purposes of the present application. The processes that have to be analyzed in this case, usually occur at a pressure of from 50 to 500×102PA. In standard GC gas from the source is served in the sampling tube under the action of excessive compared to atmospheric pressure. In this case, the gas pumped through the sampling tube at a pressure below atmospheric by means of a vacuum pump installed on the discharge of the sampling line. Since the resistance of the gas line when passing gas can cause significant pressure drop in the line, which affects the results of the calibration and sensitivity, between the metering loop and HAC the smart pump is installed valve, before entering the sample briefly closed in order to stabilize the pressure in the dosing loop and measure it with a gauge. To ensure the input of a sufficient amount of the gas sample, the volume of the gas loop is increased to 5 cm3. Depending on the design of the sampling line, this device can work effectively up to a pressure of about 70×102PA. Calibration of GC depends on the number of input samples, the required accuracy is ensured when calibrating using the same pressure, as from a source in the analysis. To obtain the correct results, you must follow the rules of work with vacuum and gases.

The sampling point can be to the camera, where the synthesis, analysis of incoming gases inside the chamber to analyze the atmosphere in the chamber, or after the camera.

As the source gas may be any known in the present technical field gas which contains carbon-containing material that when dissociation forms radicals or other reactive forms. The gas mixture typically contains gases also be used to obtain the atomic form of hydrogen or halogen.

The dissociation of the source gas is preferably carried out using microwave energy in the reactor, examples of which are well known in n the standing technical field. It is necessary to minimize the transfer of any impurities from the reactor. Microwave installation can be used to ensure the absence of contact of the plasma with all surfaces except the surface of the substrate on which the growth of the diamond and its Foundation. Examples of preferred base materials are molybdenum, tungsten, silicon, silicon carbide. Examples of preferred materials of the reaction chamber are: stainless steel, aluminum, copper, gold and platinum.

Must be used in the plasma with a high power density arising from the use of high microwave power (usually from 3 to 60 kW for substrate diameters from 25 to 300 mm) and high gas pressures (50 to 500×102PA, and preferably from 100 to 450×102PA).

Using the above conditions and additives nitrogen in the gas stream from 0.1 to 500 ppm million, the CVD method was able to obtain layers of high quality monocrystalline diamond brown color.

A thick layer of single-crystal diamond obtained by means of CVD or its fragment is then subjected to heat treatment. This fragment may, for example, have the shape of a precious stone.

The following describes embodiments of the invention. Table 1 shows the seven different combinations (referred to as case 1-7) bands n the absorption, which can be found in the single-crystal diamond brown grown by the CVD method. Spectrum analysis brown diamond obtained by the method of CVD, these absorption bands is described in detail in WO 03/052177 A1.

Line 270 nm is present in all cases and relates to isolated nitrogen atoms in substitutional positions within the crystal lattice of the diamond. It is well known that due to this defect absorption is distributed in the visible region of the absorption spectrum and gives the characteristic yellow color tone diamond type IB.

Case 1: the Nature of the spectrum slope indicates a General increase in absorption from the red to the ultraviolet region. This slope is observed in the spectrum of many layers of single-crystal diamond obtained by the CVD method, and is undesirable either by itself or in combination with isolated substitutional nitrogen, it gives a pale brown hue.

Case 2: it Is believed that a broad band of approximately 350 nm and 510 nm are associated with localized destruction of the diamond structure obtained by the method of the HOPF bifurcation that creates levels inside the forbidden zone. In samples of single-crystal diamond grown by CVD method, these bands tend to appear together. In combination with the isolated substitutional nitrogen these bands depending on the relative intensive the particular three components give hue from orange-brown to pinkish-brown.

Case 3: Brown single-crystal diamond obtained by the CVD method, may have a broad band in the near IR region of the spectrum, and if this band is heavy, its short wavelength side can cause significant absorption in the red region of the visible spectrum. This gives a blue hue. Absorption from two sides of the spectrum, resulting from a combination of this absorption with the absorption related to isolated substitutional nitrogen atoms, gives the diamond green hue.

Case 4: Range of many layers of brown single-crystal diamond obtained by the CVD method, can be represented as the sum of the contributions of isolated substitutional nitrogen, spectrum slope and strip 350/510 nm. This combination tends to give an orange-brown hue.

Cases 5, 6 and 7 cover the three other combinations of absorption lines discussed above. These combinations give different brown hues depending on the relative intensities of the absorption lines.

Table 1
270 nmTilt350 nm510 nmNear IR bandThe color of the resulting
Case 1Yes YesNoNoNoDull brown
Case 2YesNoYesYesNoPinkish-brown
Case 3YesNoNoNoYesGreen
Case 4YesYesYesYesNoOrange-brown
Case 5YesYesNoNoYesBrown
Case 6YesNoYesYesYesBrown
Case 7YesYesYesYesYesBrown

Brown single-crystal diamond obtained by the method of CVD, were annealed in order under various conditions, and have always observed the effect of annealing.

It was found that the slope of the spectrum and the 350 nm band can be largely removed by processing at 1400-1600°C for four hours at atmospheric pressure in an inert atmosphere. A similar effect can be postign the t by annealing at 1600-1700° With over four hours at a pressure stabilizing diamond. As can be seen from table 2, these treatments can have a significant impact on the color of a diamond, for example, in cases 1, 2, 4, 5, 6 and 7.

Table 2
The original colorThe final color
Case 1Dull brownLight brown / almost colorless
Case 2Pinkish-brownPink-brown to brownish-pink
Case 4Orange-brownPink-brown to brownish-pink
Case 5BrownGreen
Case 6BrownLight brown
Case 7BrownLight brown

In this temperature range is also possible a significant increase in absorption related to negatively charged complexes of nitrogen atom with a vacancy (centre N-V nathanannat line 637 nm). Increase associated with this defect absorption maximum around 550 nm) makes the color samples are more pink. The increase of absorption may be you who Vano change in the charge transfer, that translates to a larger number of centers N-V in the negative charging status. This may be caused by the formation of additional centers of nitrogen - vacancy as a result of capture exempt vacancies isolated nitrogen or dissociation, or more complex defects. You may also experience an increase in the luminescence excited by a negatively charged complexes of nitrogen - vacancy, and in exceptional cases it can affect the apparent color of the diamond.

Thus, by choosing suitable conditions of heat treatment, it is possible to obtain color single-crystal diamond grown by CVD method with fancy color from pink to green.

It was found that annealing for 4 hours at 1800°and a pressure stabilizing diamond, leads to a slight decrease in both strips 510 nm, and the band in the near IR region. What if this changes the colors for the cases examined are shown in table 3.

Case 3
Table 3
The original colorThe final color
Case 1Dull brownAlmost colorless
Case 2Pinkish-brownPink-brown to brownish-pink
GreenLess intense green
Case 4Orange-brownPink
Case 5BrownGreenish
Case 6BrownLight brown
Case 7BrownLight brown

It was found that 4-hour annealing at 1900° (C or higher temperatures and pressure, stabilizing the diamond, removes the 510 nm band and the band in the near IR region. What if this changes the colors for the cases examined are shown in table 4.

Table 4
The original colorThe final color
Case 1Dull brownAlmost colorless
Case 2Pinkish-brownAlmost colorless
Case 3GreenAlmost colorless
Case 4Orange-brownAlmost colorless
Case 5BrownAlmost colorless
Case 6 BrownAlmost colorless
Case 7BrownAlmost colorless

Under these conditions, annealing the centers of nitrogen - vacancy can dissociate with the formation of isolated substitutional nitrogen and migrating vacancies. Therefore, it is unlikely that after annealing at these or higher temperatures the centers of nitrogen - vacancy affect the color (originally brown) diamond. However, as a result of such treatments diamond exhibits intense luminescence in the green region, which can lead under certain conditions of observation and light greenish hue.

When excited by a HeCd laser with a wavelength of 325 nm in the spectra of photoluminescence brown diamond obtained by the method of CVD and annealed at temperatures high enough to cause dissociation of a significant part of the centers of the nitrogen - vacancy formed in the growth process is dominated by the bands between 450 and 550 nm. May occur H3 luminescence (nathanannat line 503 nm), and after annealing at the highest temperature can be detected N3 luminescence (nathanannat line 415 nm). With increasing time of annealing at the highest temperature when excited by UV above the forbidden zone or upon excitation by an electron beam tends p. the transfer of the dominant luminescence in the visible region of the green areas in blue.

In the spectrum of the annealed original brown single-crystal diamond obtained by the CVD method, there are other lines in the photoluminescence. For example, line photoluminescence approximately 851 nm is easily excited by laser 785 nm. Although in the spectrum of the brown diamond grown by CVD method, this line is missing, it has been found in the spectrum after annealing at temperatures up to 1200°C. This line photoluminescence never observed no other type of diamond and, apparently, is a unique feature of brown diamond obtained by the CVD method, annealed under conditions which can change its color.

Upon excitation Nd:YAG laser (1064 nm) can be observed in other lines photoluminescence: 1263 them, 1274 nm and 1281 nm. These lines have also been observed only for brown single-crystal diamond obtained by the CVD method, annealed under conditions which can change its color.

In the IR spectrum of the brown single-crystal diamond grown by CVD method, the color of which can be significantly improved by annealing, in the spectral region from 2800 to 3000 cm-1you can have absorption bands due to vibrations of links carbon-hydrogen. These bands vary considerably, but not completely removed by high temperature annealing. In the spec the arts absorption of natural or synthetic diamonds, obtained at high pressure and high temperature, these absorption bands, as a rule, are absent. Some natural diamonds are related to the hydrogen absorption line 3107 cm-1that was never observed in the spectrum of the raw diamond obtained by the CVD method. Annealing brown single-crystal diamond obtained by CVD at temperatures higher than approximately 1800°can lead to the formation of hydrogen responsible for the line 3107 cm-1. This defect is extremely stable and is observed in the spectra of samples annealed at extremely high temperatures. Thus, the line 3107 cm-1in the spectrum of the material obtained by the method of CVD suggests that the material was annealed in accordance with the method proposed in the present invention. In addition, the presence of the absorption line 3107 cm-1in combination with stripes SN-oscillations in particular indicates that a diamond is a diamond obtained by the CVD method, which has been subjected to such chemical composition of high-temperature annealing, which changed its color, as described above.

The optical characteristics described above, in addition to associated color change can be used to determine the previous history of the sample of the diamond. Definition of Pris the actions or lack of optical characteristics, this in the present description, it is known to specialists in this field of technology.

Voids in polycrystalline diamond obtained by the CVD method, can lead to a reduction in optical transmittance in the region of shorter wavelengths. Single-crystal diamond obtained by the CVD method in accordance with the present invention, does not contain voids, both before and after annealing. Top view and cross-section samples of this diamond was carefully studied using an optical microscope with high (×1000) increase. Anything that could be emptiness was not detected. Optical microscopy sets the upper limit of the size of the voids as the value of the order of 200 nm.

Microscopy penetrating electrons (IPE) allows observation of thin sections of diamond with subnanometre resolution. To clarify the possibility that the color associated with the presence of extended defects, using the IPE were obtained image a few slices of brown geotagging diamond obtained by the CVD method. In order to give a uniform color such defects should be well distributed in the crystal, to have a higher density, and thus detected the IPE. Essentially, this distribution is completely determined by the distribution of dislocations or dislocation bundles observed using techniques such as x-ray that is ografia, where dislocations penetrate in the direction of growth and occur or from defects in the substrate, or particles, or other defects on the substrate used for growing CVD method. The image area geotagging diamond obtained by the CVD method, the size of a few hundred square microns found nothing that could match the emptiness. Only in samples of very dark brown diamond was observed extended defects in the form of dislocations and defects in the packaging. On the surfaces of low - and moderate-brown specimens were investigated by means of the IPE, such extended defects were not observed.

The color coordinates can be used as a measure or means of illustration of the differences between fantasy flowers single crystal diamond produced by the method of CVD according to the method described in the present invention, and flowers that exist in other types or forms of diamond.

As in the annealed or heat treated single crystal diamond produced by the method of CVD in accordance with the present invention, it is important perceived color, and because of the color coordinates pertain to perceived color than to the spectrum bandwidth, using the color coordinates can demonstrate the new features of this diamond. According to the of the differences in absorption spectrum of the diamond received by the CVD method in accordance with the present invention, determine the perceived color, which may differ from those previously demonstrated for other diamonds obtained by CVD method, or synthetic diamonds, obtained at high pressure and high temperature.

In fact, it may be that beauty can be in the eye of the beholder, and the color tone may be subject to individual preferences. On the other hand, in the industry of diamonds is known that pink and green diamonds are valued more highly than brown, and become even more valuable with reducing the impact modifiers color. Pink or green diamond, if he has vysokosvetskoy for this saturation is most likely to provide the necessary color masterfully polished stone. It is unlikely that the polished diamond with the same hue and saturation will provide attractive color, if it has a low brightness.

In addition, in the optical and electromagnetic transmission, there are applications where, for example, it is necessary that the window had certain characteristics absorption. It may just be low the total absorption, or low absorption of certain bands, or may be required special absorption peaks, as, for example, when measuring radiation Kahlo is eletricheskimi methods. Thus, diamond, obtained in accordance with the present invention has, in particular, applications in optics. Optical applications of diamond are not limited to the visible range, and apply to the UV and IR ranges and beyond. In particular, it can be expected that this material will be used in the microwave region.

Calculating the color coordinates of CIE L*a*b*

The perceived color of an object depends on the spectrum transmittance/absorption of the sample, the spectrum energy distribution of the light source and color perception by the eye of the observer. CIE L*a*b* color coordinates presented in this patent application, was calculated, as described below. CIE L*a*b* coordinates were calculated for the diamond plate with parallel faces on the basis of its spectrum transmittance between 350 nm and 800 nm with a recording interval of 1 nm, using ratios, below, as well as the standard range of illumination D65 standard (red, green, and blue) curves of the color perception of the eye (G.Wyszecki and W.S.Stiles, John Wiley, New York-London-Sydney, 1967):

Sλ= transmittance at a wavelength of λ;

Lλ= spectral power distribution of light;

xλ= the function of the perception of the red component;

yλ= the function of the perception of the green component;

zλ= fu the Ktsia perception eye blue component;

X=Σλ[SλxλLλ]Y0;

Y=Σλ[SλxλLλ]Y0;

Z=Σλ[SλxλLλ]Y0;

where Y0λyλLλ;

L*=116(Y/Y0)1/3-16 = lightness (Y/Y0>0,008856);

a*=500[(X/X0)1/3(Y/Y0)1/3] (X/X0>0,008856, Y/Y0>0,008856);

b*=200[(Y/Y0)1/3-(Z/Z0)1/3] (Z/Z0>0,008856);

C*=(a*2+b*2)1/2= saturation;

Hab=arctan(b*/a*) = angle hue.

Outside these boundaries Y/Y0X/X0and Z/Z0should be used modified versions of these equations. Modified versions are included in the technical report of the International Commission on illumination (Colorimetry, 1986).

Usually on the chart in a* and b* coordinates and* corresponds to the x-axis, and b* corresponds to the y-axis. Positive values of a* and b* are respectively to the red and the yellow component of the color tone. Negative values a* and b* are respectively the green and blue components. The positive square graph covers hue from yellow through orange to red with weights (*) represents the distance from the origin.

It is possible to predict the evolution of a*b* coordinating the diamond with this range of absorption coefficients with changes in length of the optical path. To do this you must first from the measured spectrum of absorption coefficients to deduct the loss. Then change the absorption taking into account the different length of the optical path and then add the reflection losses. The range of absorption coefficients can be converted into a spectrum transmittance, which is used to calculate the CIE L*a*b* coordinates for the new thickness. Thus can be modeled dependence of hue, saturation and lightness of the length of the optical path, which allows you to define how the color of the diamond with the data optical properties per unit thickness will depend on the length of the optical path.

The lightness L*, is the third dimension of the color space CIE L*a*b*. It is important to understand how the lightness and saturation of a diamond with specific optical properties are changed by changing the length of the optical path. This can be illustrated on the chart colors, where L* is plotted on the y-axis, and* plotted on the x-axis (as in figure 5). The method described in the previous paragraph, can also be used to predict how the L*C* coordinates diamond with this range of absorption coefficients depend on the length of the optical path.

A wide range of values can be divided as follows: light: 95>L*>65, average: 65>L*>35, dark: 35>L*>05.

P is the performance of C* (saturation) can be separated into ranges of saturation by 10* units and described as follows:

0-10 weak

10-20 weak-moderate

20-30 moderate

30-40 moderately strong

40-50 strong

50-60 strong-very strong

60-70 is very strong

70-80+ very very strong

Example 1

A thick layer of diamond thickness of 3.2 mm were grown by the CVD method on the substrate, representing a synthetic diamond, obtained at high pressure and high temperature. The surface of the substrate, on which were growing, were prepared in accordance with the method described in WO 01/96634.

The substrate was fixed on a tungsten base, using high temperature soldering applicable for diamond, and placed in a microwave reactor. To prepare the substrate surface used etching and growth cycle, and then began to increase. The process was carried out as follows:

1) In the reactor is pre-installed purifiers, reducing the content of nitrogen in the incoming gas stream (except for the line supplements N2) to the level below 80 ppm billion, which were identified by means of GC, as described above.

2) Oxygen plasma etching in situ was performed using 30/150/1200 SMS3/s (standard cubic centimeter per second) of a mixture of O2/Ar/H2at a pressure of 235×102PA and the temperature of the substrate 840°C.

3) Without interruption began hydrogen etching at 850°With removing oxygen from a gas pot is CA.

4) Then began the process of growth by adding a carbon source, which in this case was CH4with a flow rate of 32 CCM3/C. the growth Temperature at this stage was 890°C.

5) In the growth process was introduced nitrogen (N2) with a concentration of 10 ppm million

6) after the growth substrate is removed from a reactor, and a layer obtained by means of CVD, freed from the substrate.

The concentration of single substitutional nitrogen in the layer, calculated from the absorption line 270 nm the absorption spectrum was approximately 0,40 frequent./million absorption Spectrum also contained a broad band of approximately 360 and 520 nm, and the usual increase (slope) of the absorption coefficient from the red region to the ultraviolet.

The layer was polished in a round cut diamond with 0.55 carat, which is classified as fancy light brown, group quality VS1. Then the stone was annealed at 1700°C for 4 hours under a pressure stabilizing diamond, approximately 6.5×109PA (65 kbar). The stone without any additional processing was classified as fancy light pink brown, group quality VS1.

The rounded silhouette of a diamond then increased to record quantitative absorption spectrum. The spectrum showed the absence of significant changes in the concentration of single replacement AZ is the same. The intensity of the band in the range of 360 nm and the slope of the absorption spectrum significantly decreased, but the band at approximately 520 nm remained largely unchanged.

Absorption spectrum recorded at 77 K has a weak line 637 nm (associated with vibrational bands), due to the negative charge centers of the nitrogen - vacancy. In the photoluminescence spectrum was dominated by the luminescence of defects in nitrogen - vacancy with nortononline lines 575 nm and 637 nm. Raman scattering and photoluminescence recorded at 77 K with excitation line 514 nm before and after annealing, indicating that annealing caused an increase in the photoluminescence centers of nitrogen - vacancy, and this in combination with absorption may have contributed to the change in perceived color.

Example 2

A thick layer of diamond thickness of 3.1 mm were grown by the CVD method on the substrate, representing a synthetic diamond, obtained at high pressure and high temperature, using a method similar to that described in example 1. The concentration of single substitutional nitrogen in the sample, calculated from the intensity of the absorption line 270, amounted to approximately 0.5 ppm million

The layer was polished in a round diamond of 0.49 carat, which is classified as fancy light brown, group quality VS1. Then the stone was annealed at 100° C for 24 hours under a pressure stabilizing diamond, approximately 7.5×109PA (75 kbar). After re-grinding to 0.44 carat stone is classified as fantasy, light-greenish-gray, VS1.

The silhouette of a round diamond is then increased in order to record the absorption spectrum. Absorption spectrum was insufficient to explain the green hue of the stone. In the spectrum of photoluminescence (excitation HeCd laser or Xe lamp) was attended by a strong green line luminescence-related defects, which appeared in the annealing process (N3, and other unidentified defects). In this case, the perceived green hue is mainly a result of the green photoluminescence, and its dependence on the observation conditions are consistent with this conclusion. Raman scattering and photoluminescence obtained at 77 K with excitation line 514 nm before and after annealing, indicating that annealing resulted in the decrease of the photoluminescence centers of nitrogen - vacancy, and this in combination with absorption may have contributed to the change in perceived color.

Example 3

A thick layer of diamond thickness 3,10 mm were grown by the CVD method on the substrate, representing a synthetic diamond, obtained at high pressure and high temperature, using a method similar the th described in example 1. The concentration of single substitutional nitrogen in the sample, calculated from the intensity of the absorption line 270 nm the absorption spectrum was approximately 0.5 ppm million absorption Spectrum also contained a broad band in the range of approximately 360 and 515 nm, and there was an overall increase (slope) of the absorption coefficient from the red to the ultraviolet region.

The layer was polished in a round cut diamond of 0.51 carats, which is classified as light brown, I3. Then the stone was annealed at 1700°C for 24 hours under a pressure stabilizing diamond, approximately 6.5×109PA (65 kbar). Without any additional processing stone classified as fancy light Orangevale pink, I3.

The rounded silhouette of a diamond is then increased in order to record the absorption spectrum. The spectrum showed the absence of significant changes in the concentration of single substitutional nitrogen. The intensity of the band of 360 nm and the slope in the absorption spectrum (from the red to the ultraviolet region) decreased significantly, but the band is approximately 515 nm remained largely unchanged. In the photoluminescence spectrum was dominated by photoluminescence defects nitrogen - vacancy with nortononline lines 575 nm and 637 nm. Raman scattering and photoluminescence recorded at 77 K with excitation line nm before and after annealing, indicated that annealing did not have an impact on the intensity of the luminescence centers of nitrogen - vacancy. The change in perceived color was mainly the result of changes in the absorption spectrum.

Example 4

Single-crystal diamond grown by CVD method to a thickness of 2 mm on the surface of the {100} diamond substrate, using a method similar to that described in example 1. The gas mixture consisted of 2.5 ppm million of nitrogen. The substrate was removed and produced a polished sample of Ex-4, obtained by the CVD method, having dimensions of 4.5×4,0×2 mm.

This sample had a brown color. Absorption spectrum of this sample in the UV/visible region is represented by a graph (a) in figure 1. In addition to the absorption characteristics related to single substitutional nitrogen, the spectrum contains a broad band in the range of approximately 515 nm and 365 nm. Also there has been a General increase in the absorption coefficient with respect to shorter wavelengths.

The sample was then diamond obtained by the method of CVD, were annealed at 2400°C for 4 hours under a pressure stabilizing diamond, approximately 8,0×109PA (80 kbar). After this treatment the sample was almost colorless. Absorption spectrum of the annealed sample in the UV/visible region is represented by the graph (b) in figure 1. The remaining absorption corresponds to the shape of the spectrum of the diamond type with 16 to which ncentratio single substitutional nitrogen about 1.1 ppm million Processing annealing removed additional absorption observed in the grown sample.

Using the method described previously, from the spectra of the absorption coefficients of the sample measured before and after annealing, were withdrawn CIE L*a*b* coordinates of the diamond. The results are shown in the table below. The annealing process significantly reduces the coordinate b* and saturation, and the lightness increases.

Before annealingAfter annealing
a*2,8-0,9
b*to 12.01,9
S*12,32,1
L*7286

Example 5

Single-crystal diamond grown by CVD method to a thickness of 3 mm on the surface of the {100} diamond substrate, using a method similar to that described in example 1. The process is conducted at a pressure of 250×102PA, the temperature of the substrate 815°using a gas mixture containing 7,5 frequent./million of nitrogen. The substrate was removed and produced a polished cross-section of Ex-5 diamond obtained by the CVD method, having a size of 3×2×86 mm

The sample had Orangevale-brown color. Absorption spectrum of the sample in the UV/visible region are shown in the graph (a) in figure 2. Augmented the e to the characteristics of absorption, related to single substitutional nitrogen, the spectrum contains a broad band in the range of approximately 515 nm and 365 nm. Also there has been a General increase in the absorption coefficient with respect to shorter wavelengths.

Then the sample was annealed at 1900°C for 4 hours under a pressure stabilizing diamond, approximately 7,0×109PA (70 kbar). After this treatment the sample was almost colorless. Absorption spectrum of the annealed sample in the UV/visible region is represented by the graph (b) figure 2. The remaining absorption is fairly well corresponds to the shape of the spectrum of the diamond type I6 containing approximately 2.2 frequent./million single substitutional nitrogen. Processing annealing removed additional absorption observed in the grown sample, and made a sample of almost colorless.

Using the method described previously, from the spectra of the absorption coefficients of the sample measured before and after annealing, were withdrawn CIE L*a*b* coordinates of the diamond. The results are shown in the table below. The annealing process significantly reduces the coordinate b* and saturation, and the lightness increases.

/tr>
Before annealingAfter annealing
a*4,6-0,5
b*16,83,0
S*17,43,0
L*of 58.987

Example 6

Single-crystal diamond grown by CVD method to a thickness of 1.8 mm on the surface of the {100} diamond substrate, using a method similar to that described in example 1. The process is conducted at a pressure of 257×102PA, the temperature of the substrate 812°using a gas mixture containing 3.8 frequent./million of nitrogen. The substrate was removed and measured absorption spectrum of the obtained plate Ex-6 brown diamond in the UV/visible region. Range shown in the graph (a) figure 3.

Then the sample was annealed at 1600°C for 4 hours under a pressure stabilizing diamond, approximately 6.5×109PA (65 kbar). After this treatment, the predominant colour of the sample was pink. Absorption spectrum of the annealed sample in the UV/visible region is represented by the graph (b) figure 3. This range consists of absorption related to single substitutional nitrogen concentration of approximately 1.2 ppm million, band in the range of approximately 515 nm and a residual absorption in the ultraviolet. Processing annealing removed band in the area of approximately 365 nm and significantly reduced the overall growth of the absorption towards shorter wavelengths.

Raman scattering and photoluminescence from opened is the group of laser 785 nm were obtained at room temperature before and after annealing at ramanscope Renishaw with a charge-coupled device (CCD) as a detector and microscope Olympus BH-2 (× 10 lens). It was found that the annealing treatment has added a number of lines in the photoluminescence in the near infrared region of the spectrum. They include a line approximately 851 nm and two broader lines and approximately 816 825 nm.

Using the method described previously, from the spectra of the absorption coefficients of the sample measured before and after annealing, were withdrawn CIE L*a*b* coordinates of the diamond. The results are shown in the table below. To understand what colors can be obtained from grown and annealed diamond for different optical path lengths, as described above, simulated dependence of hue, saturation and lightness of the length of the optical path. The results for the grown and annealed diamond is shown in figure 4 and 5 and are marked accordingly (a) and (b). For an arbitrary point (a*b*) in the spectrum (a) figure 4 shows the method by which is measured the angle of hue.

Before annealingAfter annealing
a*4,04,4
b*14,54,8
S*15,06,5
L*7247
The hue angle (degrees)7547

Note the R 7

A thick layer of diamond thickness 2,84 mm were grown by the CVD method on the substrate, representing a synthetic diamond type IB, obtained at high pressure and high temperature, using a method similar to that described in example 1. Growth conditions were as follows: 42/25/600 SMS3/s (standard cubic centimeter per second) of the gas mixture of CH4/Ar/N2the concentration of added N224 frequent./million, pressure 330×102PA, the temperature of the substrate 880°C.

The substrate is removed and a layer of diamond obtained by the method of CVD, finished in a faceted gemstone, obtained by the CVD method, the rectangular form of the 1.04 carats, which is a professional diamond sorter classified as having dark fantasy light orange-brown color, SI1.

Then precious stone was annealed at 1600°C for 4 hours under a pressure stabilizing diamond, approximately 6.5×109PA (65 kbar). After processing by annealing the same sorter diamond classified gemstone as having fancy intense brownish-pink color, SI1.

Example 8

A thick layer of diamond thickness of 1.3 mm is a very dark brown color was grown by the CVD method on the surface of the {100} substrate, obtained at high pressure and high temperature, using a method similar to that described in the example is 1. Growth conditions were as follows: 30/25/300 SMS3/s (standard cubic centimeter per second) of the gas mixture of CH4/Ar/N2the concentration of added15N 46 frequent./million, pressure 330×102PA, the temperature of the substrate 780°C. Used isotope15N, which is due to the influence of mass can move the lines associated with defects containing nitrogen, with values usually obtained for14N. the Substrate was removed, and a layer obtained by means of CVD, made of polished sections for experiments with annealing.

The processing conditions are listed in table 5.

Table 5
SliceTemperature (°)TimePressureThe final color
118004 hours6,5×109PAGreenish
217004 hours6,5×109PAOrangevale pink
315004 hoursNaturallyOrangevale brown
414004 hoursNaturallyBrown
512004 hours NaturallyBrown

All annealed samples, even those that were annealed in order at atmospheric pressure in argon at 1200°S, 1400°and 1500°C, showed a significant increase in the transmittance in the visible region of the spectrum, accompanied by a corresponding increase their lightness. Absorption spectra of the samples have different lines, which is shown in detail in table 6 below. In the first part of table 6 description (strong, medium, weak, very weak) give an approximate idea of the relative sizes of the bands in the spectrum. Where the description is omitted, a significant line was not observed. In the second part of table 6 "Yes" means that there was a significant amount.

As can be seen from table 6, the diamond grown and annealed in accordance with the method of the present invention, may be of absorption line missing in diamond grown by CVD method. Many of these lines had not previously observed for diamonds obtained with any other method, and, apparently, are a unique line of diamonds obtained by the method proposed in the present invention. The most obvious examples are noted in table 6 with an asterisk. Many of these lines can be observed in photoluminescence.

Table 6
Wavelength (nm)Grown1200°1400°1500°1600°1700°
270 bandStrongStrongStrongStrongStrongStrong
365 bandStrongStrong
503WeakWeakWeakWeak
510 laneAverageAverageAverageAverageAverageAverage
512Very poorAverageWeak
553WeakStrongAverageVery poor
597AverageAverageVery poor
624AverageAverage
637WeakWeakAverageWeakAverageVery poor
667*Very poorAverageWeakWeakVery poor
684*WeakWeakWeakVery poor
713Very poorAverageAverageAverageWeak
781*AverageAverageAverageWeak
851*Very poorWeakAverageStrongStrong
1000 bandStrongStrongStrongStrongStrongAverage
1263*AverageAverageAverage
1281*AverageAverageAverage
1359StrongStrongStrongAverageWeakWeak
1556AverageAverageAverageWeakWeakVery poor

Wavenumber (cm-1)Grown1200°1400°1500°1600°1700°
1332YesYesYesYesYesYes
1340*YesYesYesYes
1344YesYesYesYesYesYes
1353YesYesYesYesYesYes
1362YesYesYesYesYesYes
1371YesYesYes YesYesYes
1374*YesYes
1378*YesYes
1384*YesYes
1396*YesYesYes
1405YesYes
1453*YesYes
2695YesYesYesYesYesYes
2727YesYesYesYesYesYes
2807YesYesYesYesYesYes
Common signs SNYesYesYesYesYesYes
2949YesYesYesYesYes
3031YesYesYesYes
3054YesYesYesYesYesYes
3107Yes
3124YesYesYesYesYesYes
3310*YesYesYes
3323Yes
4677*YesYesYes

1. The way to convert a color single-crystal diamond in a different color, including the stage at which color, single crystal diamond produced by the method of chemical vapour deposition (CVD) and carry out thermal processing of the diamond at a temperature of from 1200 to 2500°and Yes the tion, stabilizing the diamond, or in an inert or stabilizing the atmosphere.

2. The method according to claim 1, wherein the single crystal diamond produced by the method of CVD, has the form of a layer.

3. The method according to claim 2, in which the layer of single-crystal diamond obtained by the method of CVD, has a thickness of more than 1 mm.

4. The method according to claim 2, in which the layer of single-crystal diamond obtained by the CVD method, the entire thickness is uniform crystal quality.

5. The method according to claim 2, in which the single-crystal diamond obtained by the CVD method, has the shape of a portion of a layer.

6. The method according to claim 5, in which a fragment of the single-crystal diamond obtained by the method of CVD, is a precious stone.

7. The method according to claim 6, in which the gemstone has three orthogonal size, each of which exceeds 1 mm

8. The method according to claim 1, in which the range of concentrations of nitrogen in solid single-crystal diamond obtained by the method of CVD ranges from 0.05 to 50 hours/million

9. The method according to claim 8, in which the lower limit of the range is 0.1 hours/million

10. The method according to claim 8, in which the lower limit of the range is 0.2 hours/million

11. The method according to claim 8, in which the lower limit of the range is 0.3 hours/million

12. The method according to claim 8, in which the upper boundary of the range is 30 hours/million

13. The method according to claim 8, in which the upper boundary of the range is 2 hours/million

14. The method according to claim 8, in which the upper boundary of the range is 10 hours/million

15. The method according to claim 1, wherein upon receipt of the diamond CVD method carried out synthesis using the gas phase, in which the nitrogen concentration is from 0.5 to 500 hours/million

16. The method according to item 15, in which the nitrogen concentration in the gas phase is from 1 to 100 hours/million

17. The method according to item 15, in which the nitrogen concentration in the gas phase is from 2 to 30 hours/million

18. The method according to one of claims 1 to 17, in which the predominant color diamond obtained by the CVD method, after the heat treatment is not brown.

19. The method according to one of claims 1 to 17, in which the color of the diamond obtained by the CVD method, after the heat treatment is in the range from pink to green in a three-dimensional color space CIE L*a*b*.

20. The method according to claim 19, in which the color of the diamond obtained by the CVD method, after the heat treatment pink.

21. The method according to claim 19, in which the color of the diamond obtained by the CVD method, after the heat treatment, fancy pink.

22. The method according to claim 19, in which the color of the diamond obtained by the CVD method, after the heat treatment of the green.

23. The method according to claim 19, in which the color of the diamond obtained by the CVD method, after the heat treatment, fancy green.

24. The method according to one of claims 1 to 7, in which the diamond obtained by the CVD method, after the heat about the abode almost colorless.

25. The method according to one of claims 1 to 7, in which the diamond obtained by the CVD method, after the heat treatment is colorless.

26. The method according to one of claims 1 to 17, in which the hue angle of the diamond obtained by the CVD method, after the heat treatment is less than 65°.

27. The method according to one of claims 1 to 17, in which the hue angle of the diamond obtained by the CVD method, after the heat treatment is less than 60°.

28. The method according to one of claims 1 to 17, in which the hue angle of the diamond obtained by the CVD method, after the heat treatment is less than 55°.

29. The method according to one of claims 1 to 17, in which the hue angle of the diamond obtained by the CVD method, after the heat treatment is less than 50°.

30. The method according to one of claims 1 to 17, in which a thick layer with parallel faces, a thickness of 1 mm, made of diamond, after the heat treatment has the coordinate b* color space CIE L*a*b* 0≤b*≤8.

31. The method according to one of claims 1 to 17, in which a thick layer with parallel faces, a thickness of 1 mm, made of diamond, after the heat treatment has the coordinate b* color space CIE L*a*b* 0≤b*≤4.

32. The method according to one of claims 1 to 17, in which a thick layer with parallel faces with a thickness of 1 mm, made of diamond, after the heat treatment has the coordinate b* color space CIE L*a*b* 0≤b*ɤ 2.

33. The method according to one of claims 1 to 17, in which a thick layer with parallel faces, a thickness of 1 mm, made of diamond, after the heat treatment has the coordinate b* color space CIE L*a*b* 0≤b*≤l.

34. The method according to one of claims 1 to 17, in which a thick layer with parallel faces with a thickness of 1 mm, made of diamond after heat treatment is the saturation (C*), which is less than 10.

35. The method according to one of claims 1 to 17, in which a thick layer with parallel faces with a thickness of 1 mm, made of diamond after heat treatment is the saturation (C*), which is less than 5.

36. The method according to one of claims 1 to 17, in which a thick layer with parallel faces with a thickness of 1 mm, made of diamond after heat treatment is the saturation (C*), which is less than 2.

37. The method according to one of claims 1 to 17, in which thermal treatment is carried out under conditions suitable to increase, modify, reduce or remove the absorption bands or other components that contribute to the color.

38. The method according to one of claims 1 to 17, in which thermal treatment is carried out under conditions suitable to reduce the concentration of defects, which cause the absorption over a wide spectral range.

39. The method according to one of claims 1 to 17, in which the single-crystal diamond obtained IU the Odom CVD, has an absorption band in the region around 350 nm, and a thermal treatment is carried out under conditions capable of changing the absorption band so that the color of the diamond is improved.

40. The method according to one of claims 1 to 17, in which the single-crystal diamond obtained by the CVD method has an absorption band around 510 nm, and a thermal treatment is carried out under conditions capable of changing the absorption band so that the color of the diamond is improved.

41. The method according to § 39, in which the change of the absorption band includes the reduction or removal.

42. The method according to p in which the change of the absorption band includes the reduction or removal.

43. The method according to one of claims 1 to 17, in which the single-crystal diamond obtained by the CVD method has an absorption band in the near IR region, which extends in the red region of the visible spectrum, and thermal treatment is carried out under conditions capable of changing the absorption band so that the color of the diamond is improved.

44. The method according to item 43, where the change of the absorption band includes the increase or decrease of its intensity.

45. The method according to claim 1, wherein thermal treatment is carried out at a temperature of at least 1600°at a pressure stabilizing diamond.

46. The method according to item 45, in which heat treatment is carried out at a temperature between 1600 and 1700°at a pressure stabilizirawe the diamond.

47. The method according to claim 1, wherein thermal treatment is carried out at a temperature not exceeding 1900°s, when the pressure in the stable graphite in an inert or stabilizing the atmosphere.

48. The method according to claim 1, wherein thermal treatment is carried out at a temperature not exceeding 1800°s, when the pressure in the stable graphite in an inert or stabilizing the atmosphere.

49. The method according to claim 1, wherein thermal treatment is carried out at a temperature not exceeding 1600°s, when the pressure in the stable graphite in an inert or stabilizing the atmosphere.

50. The method according to p, in which heat treatment is carried out at a temperature in excess of 1400°s, when the pressure in the stable graphite in an inert or stabilizing the atmosphere.

51. The method according to claim 1, wherein the inert atmosphere is an argon gas.

52. The layer of single-crystal diamond obtained by the method according to one of claims 1 to 17 for use in optics.

53. The layer of single-crystal diamond obtained by the method according to one of claims 1 to 17 for use as a window for transmission of electromagnetic radiation.

54. The layer of single-crystal diamond obtained by chemical vapour deposition (CVD) and subsequent heat treatment, with a color range from pink to green in a three-dimensional color the om space CIE L*a*b*.

55. The layer of single-crystal diamond obtained by the CVD method, item 54, which has a fancy pink color.

56. The layer of single-crystal diamond obtained by the CVD method, item 54, which has a fancy green color.

57. A layer of single crystal diamond produced by the method of the HOPF bifurcation, one of p-56, which has a thickness of at least 1 mm.

58. A layer of single crystal diamond produced by the method of the HOPF bifurcation, one of p-56, which is across the thickness is the same as crystal.

59. A fragment of single-crystal diamond obtained by the method of chemical vapour deposition (CVD), made of one layer of p-56.

60. The fragment on p, which has the shape of a precious stone.

61. The fragment on p, which has three orthogonal size, each of which exceeds 1 mm

Priority items:

06.09.2002 according to claims 1-6, 8-24, 37-51, 54-60;

05.09.2003 according to claims 7, 25-36, 52, 53, 61.



 

Same patents:

FIELD: technological process.

SUBSTANCE: invention is related to growing of garnets single crystals and may be used in laser equipment, magnet microelectronics (semi-conductors, ferroelectrics) and for jewelry purposes. Single crystals of terbium-gallium garnet are prepared by Chochralski method by means of melting primary stock, which includes clarifying calcium-containing additive, and further growing of single crystal from melt to primer. As primary stock mixture of terbium and gallium oxides is used, as calcium containing additive - calcium oxide or carbonate, and after growing crystal is annealed in atmosphere of hydrogen at temperature of 850-950°C for around 5 hours until orange paint disappears.

EFFECT: allows to prepare optically transparent homogeneous crystals.

2 ex

FIELD: carbon materials.

SUBSTANCE: monocrystalline diamond grown via chemical precipitation from gas phase induced by microwave plasma is subjected to annealing at pressures above 4.0 GPa and heating to temperature above 1500°C. Thus obtained diamonds exhibit hardness higher than 120 GPa and crack growth resistance 6-10 Mpa n1/2.

EFFECT: increased hardness of diamond product.

12 cl, 3 dwg, 5 ex

FIELD: microelectronics, namely processes for preparing even-atom surfaces of semiconductors.

SUBSTANCE: method comprises steps of chemical-dynamic polishing of substrate surface in polishing etching agent containing sulfuric acid, hydrogen peroxide and water for 8 - 10 min; removing layer of natural oxide in aqueous solution of hydrochloric acid until achieving hydrophobic properties of purified surface of substrate; washing it in deionized water and drying in centrifuge. Then substrate is treated in vapor of selenium in chamber of quasi-closed volume while forming gallium selenide layer at temperature of substrate Ts = (310 -350)°C, temperature of chamber walls Tc = (230 - 250)°C, temperature of selenium Tsel = (280 - 300)°C for 3 - 10 min. After such procedure substrate is again placed in aqueous solution of hydrochloric acid in order to etch layer of gallium selenide. Invention allows produce even-atom surface of gallium arsenide at non-uniformity degree such as 3Å.

EFFECT: possibility for using substrates for constructing nano-objects with the aid of self-organization effects.

4 dwg

FIELD: jewelry industry; optics.

SUBSTANCE: proposed method is used for coloring fianites (man-made diamonds) in green, blue and brownish-yellow colors; proposed method may be also used in optics for production of colored light filters withstanding temperatures above 1000°C. Proposed method includes preliminary application of cobalt on fianite surface to be colored and at least one metal whose oxide is liable to spinelle-forming with oxide of bivalent cobalt, iron and/or aluminum, for example. Then material is subjected to heat treatment in oxygen-containing atmosphere at temperature above 1000°C but not exceeding the fianite melting point. The procedure is continued for no less than 3 h. Coat is applied by thermal spraying of metals in vacuum. Said metals may be applied in turn and simultaneously. For obtaining bluish-green color of fianite, cobalt and aluminum are applied at atomic ratio of 1:1 to 1:2. For obtaining yellowish-green color, cobalt, aluminum and iron are applied at atomic ratio of 1:1 :0.1-0.2. For obtaining yellowish-brown color, cobalt and iron are applied at ratio of 1:1 to 1:2.

EFFECT: enhanced resistance to high temperature and chemical action.

7 cl, 11 ex

FIELD: processes and equipment for working natural and artificial origin diamonds, possibly in jewelry for refining diamonds and for imparting to them new consumer's properties.

SUBSTANCE: method comprises steps of acting upon crystal with electron beam whose integral flux is in range 5 x 1015 - 5 x 1018 electron/cm2; annealing crystal in temperature range 300 - 1900°C and acting with electron beam in condition of electric field having intensity more than 10 V/cm at least upon one local zone of crystal for imparting desired color tone to said zone. Local action of electron beams is realized through protection mask. As irradiation acts in condition of electric field local flaws such as bubbles or micro-inclusions are effectively broken.

EFFECT: possibility for producing diamonds with different local three-dimensional colored images such as letters or patterns of different tints and color ranges.

2 dwg

FIELD: electronic industry; methods of production of the crystals with the triclinic crystal system.

SUBSTANCE: the invention is pertaining to the method of production of the crystals with the triclinic crystal system. Substance of the invention: the monocrystals of lanthanum-gallium silicate grown in compliance with Czochralski method from the iridium crusible are subjected to the two-stage thermal treatment. The monocrystals are preliminary subjected to the vacuum annealing at the pressure of 1·10-2 -1·10-4Pa and the temperature of 600-1200°C within 0.5-10 hours, and then conduct their isothermal air aging at the temperature of 300-350°C within 0.5-48 hours. The invention allows reproducibly produce the discolored monocrystals of lanthanum-gallium silicate and also to speed up propagation of the surface-acoustic waves (SAW) by 1-1.5 m\s at the simultaneous decrease of dispersion of the waves propagation velocity by 20-30 ppm.

EFFECT: the invention ensures production of the discolored monocrystals of lanthanum-gallium silicate and allows to increase the speed of propagation of the surface-acoustic waves at simultaneous reduction of the waves propagation dispersion by 20-30 ppm.

FIELD: decolorizing diamonds and brilliants.

SUBSTANCE: method is realized due to physically acting in closed reaction space upon samples of diamonds and brilliants by means of high pressure and temperature for time period sufficient for enhancing their quality. Pressure acting upon samples is in range 6 - 9 GPa in region of thermodynamic stability. Temperature during physical action upon samples is in range 1700 - 2300°C. Samples are subjected to physical action in medium of graphite powder filling reaction space. Heating till high temperature is realized due to applying AC to samples of diamond or brilliant through graphite powder at specific electric current power from 0.18 kWt/cm3 and more. Then electric power is gradually increased from zero till working value and further it is decreased and increased at least two times for some time interval at each change of electric power. Process of annealing samples is completed by smoothly lowering electric current power till zero. At physical action upon sample electric current intensity is lowered by 11 - 13 % and it is increased by 15 - 17 % for time interval from 8 min and more at each change of electric power. Sample is AC heated and it is cooled at rate no more than 0.05kWt/min per cubic centimeter of reaction volume of chamber.

EFFECT: shortened time period of treating for whole decolorizing, lowered voltage values, keeping of desired parameters existing before treatment in diamonds and brilliants.

3 cl, 3 ex

FIELD: crystal growing.

SUBSTANCE: method comprises growing germanium monocrystals from melt onto seed followed by heat treatment, the latter being effected without removing monocrystals from growing apparatus at temperature within 1140 and 1200 K during 60-100 h, temperature field being radially directed with temperature gradient 3.0 to 12.0 K/cm. Once heat treatment comes to end, monocrystals are cooled to 730-750°C at a rate of at most 60-80 K/h. Monocrystals are characterized by emission scattering at wavelength 10.6 μm not larger than 2.0-3.0% and extinction not higher than 0.02-0.03 cm-1, which is appropriate for use of monocrystals in IR optics.

EFFECT: allowed growth of germanium monocrystals with high optical characteristics.

3 ex

FIELD: jewelry technology; manufacture of jewelry colored inserts.

SUBSTANCE: synthetic corundum contains alumina, color-forming additives and binder-paraffin. Required color is obtained as follows: for obtaining black color molybdenum oxide is added to alumina in the amount of 0.03%; for obtaining gray color, tungsten oxide is added to alumina in the amount of 0.01%; for obtaining blue color, neodymium oxide is added in the amount of 0.01%; for obtaining pink color, erbium oxide is added to alumina in the amount of 0.01%; for obtaining red color, chromium oxide is added in the amount of 0.05%. Proposed method of manufacture of jewelry articles includes molding in casting machines at a pressure of 4 atm and roasting; first roasting cycle is performed in continuous furnaces for burning-out the binder and is continued for 90 h at temperature of 1150 C; second roasting cycle is performed in batch furnaces at temperature of 1750 C and is continued for 170 h for forming and sintering of microcrystals making translucent crock at density of 4 g/cu cm and hardness of 9 according to Mohs hardness scale; then polishing is performed with the aid of diamond materials. Articles thus made have high-quality miniature texture at hardness which is disadvantage in relation to diamond only.

EFFECT: high quality of articles; enhanced hardness of articles.

7 cl

FIELD: chemistry.

SUBSTANCE: process of hard monocrystalline diamond preparation compises fixing of inoculating diamond in the holder and its growing by the way of chemical deposition from gaseous phase induced by microwave plasma. The process is implemented at temperature ca 1000°C - 1100°C in medium N2/CH4=0.2-5.0 and CH4/H2=12-20% at total pressure 120-220 torr. Derived monocrystalline diamond has the hardness in the range 50-90GPa and fracture strength 11-20MPa m1/2.

EFFECT: increasing of diamond hardness.

7 cl, 4 dwg

FIELD: carbon materials.

SUBSTANCE: monocrystalline diamond grown via chemical precipitation from gas phase induced by microwave plasma is subjected to annealing at pressures above 4.0 GPa and heating to temperature above 1500°C. Thus obtained diamonds exhibit hardness higher than 120 GPa and crack growth resistance 6-10 Mpa n1/2.

EFFECT: increased hardness of diamond product.

12 cl, 3 dwg, 5 ex

FIELD: crystal growth.

SUBSTANCE: method comprises separating the inoculation from the source of carbon by a metal-dissolver made of an alloy of ferrous, aluminum, and carbon when a 20-30°C temperature gradient is produced between the carbon source and inoculation. The growth zone is heated up to a temperature higher than the melting temperature of the alloy by 10-20°C, and the melt is allowed to stand at this temperature for 20 hours. The temperature then suddenly increases above the initial temperature by 10-25°C and decreases down to the initial value with a rate of 0.2-3 degree per minute.

EFFECT: improved quality of crystal.

1 tbl, 2 ex

FIELD: inorganic chemistry; mining industry; electronics; other industries; methods of the synthesis of the needle-shaped and lengthened diamonds.

SUBSTANCE: the invention is pertaining to the field of the inorganic chemistry, in particular, to the method of production of the needle shape synthetic diamonds and may be used in the industrial production of the special-purpose diamonds, for example, for manufacture of the boring crown bits and the dressers, and also in the capacity of the blocks details of the audio-video playback equipment, for manufacture of the feeler probes, in the micro-mechanical devices etc. The method provides for commixing of the fusion charge composed of the alloy of Mn-Ni-Fe in the mass ratio of 60±5÷30±5÷10±5 and the powder of the carbon-containing substance and treatment of the mixture at the pressure exceeding 40 kbar and the temperature over 950°С at heating rate less than 100°C/minutes. In the capacity of the carbon-containing substance use the needle-shaped coke or graphite on the coke basis with the single-component anisotropic structure with the degree of graphitization of no less than 0.55 relative units. The invention allows to simplify the production process of the synthesis of the needle-shaped and lengthened diamonds and to increase the percentage of their output within one cycle of the production process.

EFFECT: the invention ensures simplification of the production process of the synthesis of the needle-shaped and lengthened diamonds, the increased percentage of their output within one cycle of the production process.

2 ex, 2 dwg

FIELD: carbon materials.

SUBSTANCE: invention relates to preparation of boron-alloyed monocrystalline diamond layers via gas phase chemical precipitation, which can be used in electronics and as jewelry stone. The subject matter is uniformity of summary boron concentration in above-mentioned layer. The latter is formed in one growth sector and characterized by thickness above 100 μm and/or volume exceeding 1 mm3. Boron-alloyed monocrystalline diamond preparation involves diamond substrate provision step, said substrate having surface containing substantially no crystal lattice defects, initial boron source-containing gas preparation step, initial gas decomposition step, and the step comprising homoepitaxial growth of diamond on indicated surface containing substantially no crystal lattice defects.

EFFECT: enabled preparation of thick high-purity monocrystalline diamond layers exhibiting uniform and useful electronic properties.

44 cl, 5 tbl, 7 ex

FIELD: producing artificial diamonds.

SUBSTANCE: method comprises preparing diamond substrate virtually having no defects, preparing the initial gas, decomposing initial gas to produce the atmosphere for synthesis that nitrogen concentration of which ranges from 0.5 to 500 particles per million, and homogeneous epitaxy growth of diamond on the surface.

EFFECT: increased thickness of diamond.

40 cl, 9 dwg, 5 ex

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

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

FIELD: treatment of diamonds.

SUBSTANCE: proposed method of change of diamond color includes the following stages: (i) forming reaction mass at presence of diamond in pressure-transmitting medium fully surrounds the diamond; (ii) subjecting the reaction mass to action of high temperature and pressure during required period of time; proposed diamond is brown diamond, type IIa; its color is changed from brown to colorless by subjecting the reaction mass to action of temperature of from 2200°C to 2600°C at pressure of 7.6 Gpa to 9 Gpa.

EFFECT: possibility of keeping diamond intact during treatment.

46 cl, 4 dwg, 1 ex

FIELD: physics; microelectronics.

SUBSTANCE: device intended to produce layers from gas phase at reduced pressure that includes a deposition chamber composed of an inner reactor in the form of horizontal pipe with longitudinal holes in its walls arranged regularly in a checkered pattern, which is installed coaxially with outer reactor implemented as horizontal pipe to form with said inner reactor a chamber for gaseous chemical agents supply equipped with nipples for gaseous chemical agent injection, an evacuation system equipped with three vacuum gates, two of which located in the evacuation system of vacuum pump connected to the ends of said deposition chamber via evacuation chambers, and the third gate located between them symmetrically to the deposition chamber, and a heater. The gaseous chemical agent supply chamber is equipped with an additional nipple implemented in the form of evacuated quartz tube inserted to the middle of the gaseous chemical agent supply chamber, provided that outlet of the additional nipple is located between longitudinal holes of the inner reactor.

EFFECT: provision of isothermic and isobaric conditions of layer depositing; results in elimination of inhomogeneity of layer properties over depositing zone.

2 dwg

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