Method of improvement of diamond color at high temperature and high pressure (versions)

FIELD: treatment of diamonds.

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

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

31 cl, 4 dwg, 2 ex

 

Background of invention

This invention relates to a method of improving the color of the diamond.

Diamonds usually are divided into four main types: Ia, Ib, IIa and IIb. These types usually differ in the infrared and ultraviolet spectra. The diamonds are type Ia and Ib contain nitrogen in a combination of different forms. Diamond type Ib contains single substitutional nitrogen atoms or centers. Diamond type Ia contains a combination of different structures of the nitrogen atoms. Diamonds of type IIa have a nitrogen content of less than a few parts per million and can be characterized as diamonds, which do not exhibit essentially no absorption in the range 1332-400 cm-1irradiated by infrared radiation. Diamond type may have a brown color, due, as I believe, structural deformation within the crystal lattice of the diamond. The type IIb diamonds are the concentration of nitrogen is less than a few parts per million and the concentration of substitutional boron atoms, which exceeds the concentration of nitrogen defects, resulting in uncompensated properties of semiconductor p-type (i.e. semiconductor with hole conductivity). The absorption of the diamond in the visible region, decreasing in intensity with decreasing wavelength, results in or blue.

The combination of blue or blue BL is due to the presence of boron and brown, due to structural deformation in the type IIb diamond, leads to color from bluish-gray to brownish-gray, depending on the relative intensities of the respective acquisitions.

In U.S. patent 4124690 described method of converting nitrogen type Ib nitrogen to type Ia in diamond type Ib by high-temperature annealing under pressure, which prevents graphitization. The result of this processing is to reduce the yellow color of the diamond type Ib.

The invention

In accordance with the present invention, a method for improving the color of a diamond, comprising the stage of: (i) creating a reaction mixture by ensuring the presence of diamond in a pressure-transmitting medium, which completely surrounds the diamond, and (ii) impact on the reaction mass to high temperature and pressure for a suitable period of time, characterized in that a diamond is a diamond type IIb and its color will change from gray to blue or blue or increased by treatment of the reaction mass temperature in the range from 1800°2600°when the pressure of 6.7 GPA up to 9 GPA.

In accordance with the present invention a method for improving the color of a diamond, comprising the stage of: (i) creating a reaction mixture by ensuring the presence of diamond in a pressure-transmitting medium, which completely OCD is worn a diamond. and (ii) impact on the reaction mass to high temperature and pressure for a suitable period of time, characterized in that a diamond is a diamond containing boron type II, and its color is changed to blue or blue by treatment of the reaction mass temperature in the range from 1800°2600°at a pressure of 6.7 GPA up to 9 GPA.

The type IIb diamonds are the concentration of nitrogen is less than a few parts per million and the concentration of substitutional boron atoms, which exceeds the concentration of nitrogen defects, resulting in uncompensated properties of semiconductor p-type, i.e. semiconductor with hole conductivity. Typical absorption spectra of type IIb diamond in the infrared, visible and ultraviolet spectral regions shown in figure 1. The present invention is applicable for the type IIb diamond, which has a gray color. Grey color may vary from gray to brownish-gray, while its spectrum is characterized by a monotonically increasing intensity of absorption with decreasing wavelength, as shown in figure 2 using the line (s) of the graph. After heat treatment, the diamond of the present invention receive or amplify light blue or dark blue color and diamond has a spectrum, which is characterized by the decrease of the absorption at low wavelengths, as shown in figure 2 using line (b).

<> Blue diamond reinforce by using an annealing temperature in the range from 1800°With up to approximately 2600°C. generally, the higher the annealing temperature, the shorter the period of annealing. As a rule, do not use the duration of annealing in excess of 20 hours. Preferably the annealing temperature is between 2200°2500°C, and the annealing is performed under a pressure of 6.7 HPa to 8.4 GPA, and preferably under a pressure of 7.6 HPa to 8.4 GPA, during the period of from 10 minutes to 15 hours, and preferably of 1 hour. Examples of suitable annealing conditions are as follows: 2500°C for 1 hour; 2500°C for 10 minutes; 2100°20 hours; 2300°C for 5 hours.

Description of embodiments

In accordance with the present invention, the diamond crystal type IIb, which has a color ranging from gray to brownish-gray and, as a rule, is a natural diamond, is subjected to annealing under pressure, which prevents significant graphitization to modify the structural deformation of the diamond, which causes staining in brown color, thereby reducing staining in brown and enhancing the blue color of the diamond. In some cases, the initial boron concentration is so low that the dominant influence on the absorption has to mponent, cause staining in brown color, resulting in a brown diamond. In addition, in some cases, boron cannot be detected by the absorption in the original diamond, possibly due to the effect called charge compensation. It should be understood that both of these diamonds are covered by the term "grey diamond type IIb"used in this description and in the claims.

Blue or natural blue diamonds are rare. Thus, in accordance with the present invention, a method of gain or blue natural diamond type IIb, without causing damage to the diamond crystal.

Color changing crystal diamond type IIb can be quantitatively evaluated due to changes in the absorption spectrum of the crystal, obtained before and after annealing. Absorption spectra of the crystal get at room temperature using a spectrometer in the usual way, which allows to obtain the absorption spectrum of the crystal in the UV and visible region. After annealing the crystal again receive its spectra at room temperature. Processing of diamond crystals of type IIb in accordance with the method of annealing according to this invention leads to a decrease monotonically increasing absorption, the main absorption remains on the waves of greater length, resulting in increased is by blue or blue color. The use of the method of annealing according to the invention also increases the concentration of uncompensated boron. It also enhances or blue.

In accordance with the method according to the invention, the reaction mass is generated by the availability of diamond in a pressure-transmitting medium, which completely surrounds the diamond. Preferably, the reaction mass is generated by sealing a pressure-transmitting medium around the diamond before placing the diamond in the reaction zone of the plant for treatment at a high temperature and high pressure.

Transmitting the pressure medium is preferably a homogeneous transmitting pressure environment, which provides a uniform distribution of pressure, the application of which operate on the entire surface of the diamond, which is subjected to processing. Examples of suitable media are those that have low shear strength, such as metal salts, for example, halide salts of metals. Transmitting the pressure medium may be a salt of a noble metal. Examples of suitable halide salts of metals are potassium bromide, sodium chloride, potassium chloride, cesium chloride, cesium bromide, copper chloride and copper bromide. It was found that such environments provide the desired uniform distribution of pressure is Oia, that ensures that any graphitization that can occur on the surface of the diamond will be minimal. A special advantage of the use of halide metal salt as a pressure-transmitting medium is that diamonds can be easily extracted after processing by dissolving this environment in hot water.

The method according to the invention can be used for processing a single diamond or multiple discrete (separate) diamonds. If multiple diamonds will be processed at the same time, each diamond must be separated from adjacent diamonds a pressure-transmitting medium. The maximum volume of the diamond, which can be subjected to processing is limited only by the capacity of the used setup for processing at high pressure and high temperature.

To implement the method according to the invention it is possible to use the typical installation for processing at high temperature and high pressure. In the patent literature discloses various designs reaction vessels, which provide indirect or direct heating of the reaction mass, and they are suitable for implementing the method of annealing according to the present invention. These reaction vessels are typically composed of many inserted into each other (adjusted to each other) of the cylindrical elements and the limit is ilosec or disks for holding the reaction mass in the Central cylinder. In a reaction vessel with indirect heating one of the cylindrical elements made of graphite, which is heated by passing an electric current through it, and which thereby heats the reaction mass. In a reaction vessel with a direct heating of the reacting mass is conductive, avoiding the need to use a cylinder of electrically conductive graphite, and an electric current is passed directly through the reacting mass to heat it.

The invention is illustrated with the following examples.

Example 1

Was used natural brownish-grey diamond type IIb with the absorption spectrum in the ultraviolet and visible region before processing, shown in figure 2 as line (a). Many of these diamonds was placed in transmitting the pressure medium in the reaction vessel of this type, as illustrated in figure 3. As shown in this figure, the crystals 10 diamonds placed in transmitting the pressure medium 12 so that the crystals are isolated (discrete) and separated from each other in a pressure-transmitting medium. Diamonds, preferably evenly distributed in the environment. Transmitting a pressure medium, preferably, represents an environment with low resistance to shear of the type indicated above. Containing diamonds Wednesday 12 apartments which are in the container 14, made of graphite, pyrophyllite, magnesium oxide or zirconium oxide, completely surrounded vzaimopodchinennym metal caps 16, 18, which form a metal enclosure around the container 14. The metal may be molybdenum, tantalum or steel. The housing can be pressed against the container to eliminate air pockets. The container is loaded in the housing is then placed into the reaction zone of a typical installation for processing at high temperature and high pressure. The contents of the capsules were subjected to a temperature of 2200°and the pressure of 7.6 GPA, while this mode is continued during the period of 12 hours. The capsule was removed from the installation and provide the capability of its cooling. Case and graphite container was removed, and the diamonds were extracted from the environment. Absorption spectrum of the diamond in the ultraviolet and visible region after processing is shown in figure 2 as line (b). The spectrum shows a decrease in brown background after annealing. Because the absorption spectrum is now dominated by absorption in the red end of the spectrum, decreasing with decreasing wavelength, the diamond looks blue or blue.

Example 2

Natural brownish-grey diamond type IIb subjected processed in the same manner as basically outlined in example 1, except that the temperature oti the ha was 2500° When the pressure indicated in example 1, and these conditions were maintained for a period of 1 hour. Absorption spectrum in the ultraviolet and visible region before processing is shown in figure 4 in a line (a), while the absorption spectrum of the diamond in the ultraviolet and visible region after processing is shown in figure 4 in a line (b). In this case, the spectrum is also characterized by a decrease in brown background after annealing. In addition, increased absorption in the red part of the visible spectrum, resulting in more saturated or blue, partly due to the increase in the concentration of uncompensated boron.

1. Method for improving the color of a diamond, including stage

(i) creating a reaction mixture by ensuring the presence of diamond in a pressure-transmitting medium, which completely surrounds the diamond; and

(ii) impact on the reaction mass to high temperature and pressure for a suitable period of time,

characterized in that a diamond is a diamond type IIb and its color will change from gray to blue or blue or increased by treatment of the reaction mass temperature in the range from 1800 to 2600°at a pressure of from 6.7 to 9 GPA.

2. Method for improving the color of a diamond, including stage

(i) creating a reaction mixture by software is ice diamond in a pressure-transmitting medium, which completely surrounds the diamond; and

(ii) impact on the reaction mass to high temperature and pressure for a suitable period of time,

characterized in that a diamond is a diamond containing boron type II, and its color is changed to blue or blue by treatment of the reaction mass temperature in the range from 1800 to 2600°at a pressure of from 6.7 to 9 GPA.

3. The method according to claim 1 or 2, characterized in that the period of heat treatment in stage (ii) does not exceed 20 hours

4. The method according to claim 1 or 2, characterized in that in stage (ii), the reaction mass is subjected to heat and pressure for a period of from 10 minutes to 15 hours

5. The method according to claim 1 or 2, characterized in that in stage (ii), the reaction mass is subjected to heat and pressure for about 1 o'clock

6. The method according to any of the preceding items, wherein the temperature in stage (ii) is from 2000 to 2500°C.

7. The method according to any one of claims 1 to 5, characterized in that the temperature in stage (ii) is from 2200 to 2500°C.

8. The method according to any of the preceding paragraphs, characterized in that the pressure in stage (ii) is from about 7.6 to 8.4 GPA.

9. The method according to any of the preceding paragraphs, characterized in that before the impact on the diamond of temperature and pressure range of diamond in the ultraviolet and visible region, the STI is characterized by a monotonically increasing intensity of absorption with decreasing wavelength, and the fact that after exposure to the diamond of temperature and pressure, the diamond has a spectrum, which is characterized by the decrease of absorption at low wavelengths.

10. The method according to claim 9, wherein after exposure to the diamond of temperature and pressure, the diamond has a spectrum that is characterized by increased absorption in the red part of the visible spectrum, partly due to the increase in the concentration of uncompensated boron.

11. The method according to any of the preceding paragraphs, characterized in that the set of diamonds are placed in transmitting pressure environment, with each diamond is separated from the adjacent diamond a pressure-transmitting medium.

12. The method according to any of the preceding items, wherein transmitting the pressure medium is a homogeneous environment, which completely surrounds the diamond or each of the diamond and which is applied over the entire surface of a diamond or of each of the diamonds.

13. The method according to any of the preceding paragraphs, characterized in that the reaction mass is generated by sealing a pressure-transmitting medium around the diamond before placing the diamond in the reaction zone of the plant for treatment at a high temperature and high pressure and influence on the reaction mass to conditions of stage (ii).

14. The method according to any of the preceding items, wherein transmitting the I pressure environment to a low shear strength.

15. The method according to any of the preceding items, wherein transmitting the pressure medium is soluble in water.

16. The method according to any of the preceding items, wherein transmitting the pressure medium is a salt of the metal.

17. The method according to any one of claims 1 to 15, wherein transmitting the pressure medium is a halide salt of the metal.

18. The method according to 17, characterized in that the halide is a chloride or bromide.

19. The method according to any of PP-18, wherein transmitting the pressure medium is a salt of an alkali metal.

20. The method according to any of PP-18, wherein transmitting the pressure medium is a salt of a noble metal.

21. The method according to item 16 or 17, wherein transmitting the pressure medium is a salt of potassium.

22. The method according to item 16 or 17, wherein transmitting the pressure medium is a sodium salt.

23. The method according to item 16 or 17, wherein transmitting the pressure medium is a salt of cesium.

24. The method according to item 16 or 17, wherein transmitting the pressure medium is a salt of copper.

25. The method according to any one of claims 1 to 13, wherein transmitting the pressure medium is a bromide of potassium.

26. The method according to any one of claims 1 to 13, distinguishing the I, that transmits the pressure medium is sodium chloride.

27. The method according to any one of claims 1 to 13, wherein transmitting the pressure medium is potassium chloride.

28. The method according to any one of claims 1 to 13, wherein transmitting the pressure medium is a caesium chloride.

29. The method according to any one of claims 1 to 13, wherein transmitting the pressure medium is a bromide cesium.

30. The method according to any one of claims 1 to 13, wherein transmitting the pressure medium is a chloride of copper.

31. The method according to any one of claims 1 to 13, wherein transmitting the pressure medium is a copper bromide.



 

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SUBSTANCE: the invention is pertaining to the field of high power industry, mechanical engineering and environmental control. In a explosion-proof chamber 1 with double-walls simultaneously feed a gaseous explosive mixture using pipeline 4 through channels 5 and inject hydrocarbons with the nucleuses of carbon crystallization using a pipeline 6 through an injector 7 with formation of a cone-shaped shell 8 with an inert cavity in the central zone. The shell 8 and the explosive mixture 9 form a cumulative charge. Conduct initiation of undermining of an explosive mixture 9, as a result of which the cumulative charge forms a cumulative spray 10 moving at a high speed along the axis of the cumulation. The gaseous products withdraw through pipeline 17. At collision of the cumulative spray 10 with a barrier having channels 11 of the cooling unit 2 the pressure and temperature there sharply increase ensuring growth of the formed crystals of diamond. Simultaneously conduct cooling with the help of pipelines 12 located in metal filings and granules 13. The atomized and cooled cumulative spray gets into the auxiliary chamber 3, where the diamonds 14 are separated, feed through the pipeline 15 to a power accumulator 16, in which they are settling. Separated hot hydrogen is removed for storing or utilization. The invention allows to magnify the sizes of dimensions crystals of diamond up to 800 microns and more, to decrease atmospheric injections, to reduce the net cost of the diamonds, to increase effectiveness of the device.

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SUBSTANCE: proposed method includes the following stages: (i)forming of reaction mass at presence of diamond pressure-transmitting medium which fully surrounds it; (ii) action on reaction mass by high temperature and pressure during required period of time; proposed diamond is brown diamond, type IIa; its color is changed from brown to rose by action on reaction mass by temperature from 1900°C to 2300°C at pressure from 6.9 GPa to 8.5 GPa.

EFFECT: enhanced efficiency of enriching diamond color keeping its crystals intact.

30 cl, 4 dwg, 1 ex

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