Method for making fancifully coloured orange monocrystalline cvd-diamond, and finished product

FIELD: metallurgy.

SUBSTANCE: monocrystalline diamond material that has been grown using a CVD method and has concentration of single substituent nitrogen [Ns0] of less than 5 ppm is irradiated to introduce isolated vacancies V to at least some part of the provided CVD-diamond material so that total concentration of isolated vacancies [VT] in the obtained diamond material is at least more than (a) 0.5 ppm and (b) by 50% more than concentration [Ns0] in ppm in the provided diamond material; after that, annealing of the obtained diamond material is performed so that chains of vacancies can be formed from at least some of the introduced isolated vacancies at the temperature of at least 700°C and maximum 900°C during the period of at least 2 hours; with that, irradiation and annealing stages reduce the concentration of isolated vacancies in diamond material, due to which concentration of isolated vacancies in the irradiated and annealed diamond material is <0.3 ppm.

EFFECT: diamonds obtain fancifully orange colour during such treatment.

16 cl, 3 dwg, 4 tbl

 

This invention relates to a method of manufacturing fancy orange single crystal diamond material pokerstove processing the diamond material that has been grown by the CVD method (chemical vapour deposition), and single-crystal CVD diamond material that has a fancy orange color.

The term "fancy colored diamonds" is established in the trading of precious stones classification term used to describe unusual colored diamonds. Educational history and qualifications framework sorts of fancy colored diamond precious stones, including the use of color charts Manzella provided by the authors of the king (King) and others in the edition of Gems &Gemology, vol 30, No. 4, 1994 (pp. 220-242).

In the prior art examples of fancy colored synthetic and natural diamonds, made the introduction of diamond color centers. For example, ERA and ERA describe irradiation of synthetic diamond material electron beam or a neutron beam for the formation of lattice defects (defects introduce isolated vacancies in the crystal. After that, the diamond crystal is annealed in a preset temperature range for the formation of color centers. None of these publications do not disclose ora is Zhevago diamond material.

Another publication describing the formation of a fancy colored diamond material is "Optical Absorption and Luminescence" ("Optical absorption and luminescence") John Walker (John Walker), published in Reports on Progress in Physics, volume 42, 1979. This publication likewise describes a stage of formation of lattice defects in the crystal by electron beam irradiation and, if necessary, annealing to cause the merger of lattice defects with nitrogen atoms contained in the crystal. In this publication there is no disclosure orange diamond material.

US 2004/0175499 (name Twitchen and others) describes how, beginning with painted CVD-diamond, usually brown or almost brown, and applying prescribed heat treatment to obtain other desirable color in the diamond. This is known from the prior art, the source noted that the relative intensity of the absorption bands in the visible region of the spectrum brown single-crystal CVD diamond can be changed by annealing with simultaneous changes in the Raman spectrum, and that changes in the absorption spectrum are observed at much lower temperatures than required to change the color brown natural diamond. As indicated, a significant color change is achieved by annealing at atmospheric pressure in an inert is atmosphere at temperatures of 1600°C. or less. One example describes the grown CVD diamond cut round diamond weight of 0.51 carats, which was classified as light brown. After annealing at 1700°C for 24 hours it was described as a bright orange-pink. Another example describes a slice grown CVD diamond, which had an orange-brown color, and after annealing this color became colorless. Additional example describes the layer grown CVD diamond cut gemstone with a rectangular cut weight was 1.04 carats, which was described as having a fancy dark orange-brown color. After annealing at 1600°C for four hours he bought fancy intense brownish-pink color.

We found that fancy orange color, you can bring in the synthetic CVD diamond material by irradiation of synthetic CVD diamond material for a time sufficient for introduction into the diamond material isolated vacancies with a given concentration, and then annealing it contains isolated vacancies CVD diamond material for a sufficiently long time at a low temperature to obtain fancy colored orange diamond material. It seems that during low-temperature annealing at least some of these isolated vacancies in CVD-diamond is the material is converted into a chain of vacancies and that these chains vacancies are responsible for the perceived fancy orange diamond material.

The first aspect of the present invention is a method of making fancy orange synthetic CVD diamond material containing: (i) predusmatriva single crystal diamond material that has been grown by the CVD method and has a concentration of [Ns0] less than 5 ppm; (ii) irradiation provided CVD diamond material in order to introduce isolated vacancies V in at least part of the provided CVD diamond material so that the total concentration of isolated vacancies [VT]=([V0]+[V-]) in the irradiated diamond material was at least more of (a) 0.5 ppm and (b) 50% higher than the concentration [Ns0] in ppm in the provided CVD diamond material, and (iii) annealing the irradiated diamond material at a temperature of at least 700°C. and at most 900 ° C for a period of at least 2 hours, optionally at least 4 hours, optionally at least 8 hours, thereby forming a chain of vacancies of at least some of the entered isolated vacancies.

According to the first aspect of the invention, the total concentration of isolated vacancies [VT]=([V0]+[V-]) in the irradiated diamond material is at least the greater of (a) 0.5 ppm and (b) 50% higher than the concentration [Ns0] in ppm in the provided CVD diamond material is E. This means that the total concentration of isolated vacancies [VT]=([V0]+[V-]) always has a minimum value of 0.5 ppm even for low or zero concentrations of [Ns0] in the provided CVD diamond material. At concentrations of [Ns0] in the provided CVD diamond material above around 0.33 ppm minimum value of the concentration of isolated vacancies [VT]=([V0]+[V-]) in the irradiated diamond material is specified with 50% higher than the concentration [Ns0] in ppm in the provided CVD diamond material, as this will result in a value for the concentration of isolated vacancies [VT]=([V0]+[V-]) more than 0.5 ppm.

In some embodiments of the invention stage of irradiation and annealing is carried out so as to reduce the concentration of isolated vacancies, [VT], to a concentration of <0.3 ppm.

Fancy colored orange diamond material produced by the method according to the present invention, can be used as gemstones. Also provided by other applications, for example, use as a color filter or a cutting instrument such as a scalpel.

Diamond is a material that provides for stage (i) of the method called in this description "provided by diamond. When pushing the actual growing CVD diamond material may be or not be part of the method according to variants of the invention. Predusmatriva CVD diamond material may simply mean, for example, the choice of pre-grown CVD diamond material. Diamond material after stage (ii) irradiation is called "irradiated diamond and diamond material stages after irradiation and annealing is called "treated diamond material" or "irradiated and annealed diamond material. Stage (i) to (iii) options for implementing the methods of the present invention, describing the diamond material at each stage of the method, illustrated in the block diagram in Figure 1.

Provided CVD diamond material in the method according to the present invention has a concentration of [Ns0] (which represents the concentration of neutral defects of single substitutional nitrogen) less than 5 ppm, optionally less than 4 ppm, optionally less than 3 ppm, optionally less than 2 ppm, optionally less than 1 ppm. The color of the provided CVD diamond material may vary according to the concentration [Ns0] and the mode in which it was grown diamond material. It is known that defects [Ns0] tell diamond material yellow staining, especially at concentrations above 0.3 ppm, but the specialist will be clear that the observed color is associated with concentration and optical path length through the diamond. It is also known that presets the ance low nitrogen concentrations in the environment CVD cultivation may affect the nature and concentration of other defects, which are introduced into the CVD synthetic diamond material as the growth of the diamond material, and that at least some of these other defects give color centers, contributing to the color of the CVD diamond material, typically giving the diamond material brown staining. All measurements to calculate the concentration of Ns0perform after excitation by UV radiation.

It seems that the color centers, which contribute to the brown staining of CVD diamond grown in the presence of low concentrations of nitrogen, are unique to single-crystal CVD diamond, or fragments, cut or obtained from layers of single-crystal CVD diamond. In addition, it is known that the color centers, contributing to the brown coloration CVD-diamond, different from the color centers, contributing in any brown staining observed in natural diamond, because defects in CVD diamond material cause of the absorption band in the absorption spectra of the grown CVD diamond material not found in the absorption spectra of natural diamond. The proof follows from Raman scattering from non-diamond carbon observed at infrared excitation source (e.g., 785 nm or 1064 nm), which is not observed for brown prirodno the diamond. In addition, it is known that these color centers in natural diamond material parts are annealed at a different temperature than in CVD diamond material.

It appears that some of the color centers, contributing to the brown coloration, visible in CVD synthetic diamond grown using methods that introduce nitrogen at low concentrations, are related to localized disturbance of the relations of atoms of diamond inside a single-crystal CVD diamond. The precise nature of the defects is not well understood, but the use of the methods of electron paramagnetic resonance (EPR) and optical absorption spectroscopy to study the nature of the defects, to some extent, have improved our understanding. The presence of nitrogen in the grown CVD synthetic diamond material can be confirmed by examination of the absorption spectra of the grown CVD diamond material, and the analysis of these spectra gives some indication about the relative shares of different types of existing defects. A typical spectrum of the grown CVD synthetic diamond material grown in the presence of nitrogen, was added in Wednesday synthesis, exhibits a peak at about 270 nm, which is caused by the presence of neutral atoms single substitutional nitrogen (Ns0in the crystal lattice of the diamond. Additional peaks were observed at about 350 nm and about 10 nm, consistent with other defects, characteristic and unique for CVD synthetic diamond material, and besides, there was a so-called "tilt", which is an increasing level of background in the form s×λ-3, where C is a constant, and λ is the wavelength. Although Ns0can be identified mainly by its peak at 270 nm, it is also, to a lesser extent, contributes to the absorption spectrum at higher wavelengths, in particular at wavelengths in the visible spectrum, which is usually considered covering the wavelength range from 350 nm to 750 nm.

There is a combination of signs, manifested in the visible part of the absorption spectrum of CVD diamond material, that is, (a) the contribution of Ns0in the visible part of the absorption spectrum, (b) peak at 350 nm, (C) peak at 510 nm and (d) the sign of the slope, which affect the perceived color of the diamond material and appear responsible for the brown color, typically observed in nitrogen-doped CVD synthetic diamond material. Peaks at 350 nm and 510 nm are not visible neither in absorption spectra of natural diamond, nor in the absorption spectra of other synthetic diamonds, for example, synthetic VDT-diamonds of the type described in ERA. For the purposes of this description all defects other than Ns0-defects, which contribute to the absorption spectrum in the visible h the STI spectrum we discussed above how the signs of 350 nm, 510 nm and tilt will be collectively called "X-defects". As noted above, currently, the structural nature of these defects at the atomic level are unclear, and the only clear is their influence on the absorption spectra of the grown diamond material. Without any limitation of the invention, it appears that the nature of the defects responsible for the brown coloration, could be related to the presence of mnogovershinnyi clusters (each cluster consists of dozens of vacancies, for example, 30 or 40 or more vacancies)that arise when growing with high speed growth, along with the addition of nitrogen to the plasma in the hydrogen-methane (H2/CH4) gas source. Such clusters are thermally unstable and to some extent can be removed by high-temperature processing (i.e. annealing). It seems that the smaller relating to the vacancy defects, such as defects NVH (nitrogen-vacancy-hydrogen), which is formed by nitrogen and hydrogen, and a missing carbon atom, may be partly responsible for the brown color, and these defects can be removed by high-temperature processing.

In preferred methods according to the invention, the absorption coefficients at 350 nm and 510 nm for the envisaged diamond mother of the La are less than 3 cm -1and 1 cm-1accordingly, it is not necessarily less than 2 cm-1and 0.8 cm-1respectively.

Depending on the method of manufacture and on the concentration [Ns0] just grown CVD diamond material provided CVD diamond material used in the methods according to the invention may typically look colorless, nearly colorless or yellow or brown, with a saturation C* mild to moderate and lightness L* from very light to medium (values S* and L* more details are discussed later in this description). Concentration [Ns0] in the provided diamond material is less than 5 ppm, which limits any yellow staining of the diamond material. For certain variants of realization according to the invention, the absorption coefficients at 350 nm and 510 nm is less than 3 cm-1and 1 cm-1accordingly, it is not necessarily less than 2 cm-1and 0.8 cm-1accordingly, the absorption coefficients at these wavelengths represent the measure of korichnevoto diamond material as X-defects appear responsible for most of the brown staining, due to the aforementioned X-defects in the diamond material grown CVD method with the introduction of the nitrogen gas source.

In accordance with another variant implementation of the methods according to the SNO present invention, provided CVD diamond may contain or not contain Ns0. Where it contains the Ns0the concentration of [Ns0]present in the synthetic CVD diamond material according to the present invention can be measured using EPR for levels <5×1015cm-3and using the methods of spectroscopy optical absorption in the UV/visible region for higher concentrations. These methods are applicable for samples after exposure to UV-light.

Contents [Ns0] neutral uncharged condition can be measured using electron paramagnetic resonance (EPR). Although this method is well known in the art, it is summarized here for completeness. In the measurements performed using the EPR, the prevalence of specific paramagnetic defect (for example, defect neutral single substitutional nitrogen) proportional to the integrated intensity of all the resonance lines of the EPR absorption determined by the center. This allows to determine the concentration of the defect by comparing the integrated intensity to that which was observed for the reference sample, provided that the taking of measures to prevent saturation effects of microwave power or the introduction of amendments to them. Since the EPR spectra in staz is opened continuous exposure record using field modulation, to determine the intensity of the EPR signal, and thereby the concentration of the defect requires double integration. To minimize errors associated with double integration, baseline correction, the ultimate limits of integration, and so on, especially in those cases where there are overlapping EPR spectra, to determine the integrated intensity of the EPR centers present in the sample, using the method of spectral approximation (using the simplex method neldermead (J.A. Nelder and R. Mead, The Computer Journal, volume 7 (1965), page 308)). This reach reconciliation experimental spectra with simulated spectra of defects present in the sample, and determining the integrated intensity of each simulation. Experimentally observed that a good agreement with the experimental EPR spectra does neither Lorentz nor Gaussian line shape, therefore, to obtain the simulated spectra used distribution function Tsallis (D.F. Howarth, J.A. Weil, Z. Zimpel, J. Magn. Res., volume 161 (2003), page 215). In addition, in the case of low concentrations of nitrogen is often necessary to apply the modulation amplitudes approaching the line width of the EPR signals or exceed it, to achieve a good ratio "signal/noise" (which provides the ability to accurately determine the concentration at which the limits of acceptable time frame). Therefore, attract a pseudo-modulation, with the shape of the line on Tsallis to get good agreement with the recorded EPR spectra (J.S. Hyde, M. Pasenkiewicz-Gierula, A. Jesmanowicz, W.E. Antholine, Appl. Magn. Reson., volume 1 (1990), page 483). Using this method, the concentration in ppm can be determined with a reproducibility of better than ±5%.

The method of absorption spectroscopy in the UV/visible region for measuring higher concentrations [Ns0] is well-known in the art and includes measurements with the peak at 270 nm the absorption spectrum of the diamond material.

Provided diamond material according to the present invention can be grown using conventional CVD method, for example, of the type disclosed in WO 03/052177. This method, as noted above, may cause the diamond material that has some brown staining, but provided that this brown staining is not too intense, it can be masked introduced orange staining, the resulting pokerstove processing by irradiation and annealing method according to the present invention.

Another CVD method of cultivation, which can be used to obtain the provided CVD diamond material is a CVD-method of cultivation in which the gas source contains carbon, water the rod, nitrogen and oxygen, rather than the more familiar carbon, hydrogen and nitrogen. For example, oxygen may be added to the process gas at a concentration in the gas phase at least 10000 ppm. In particular, the provided CVD diamond material in stage (i) of the method according to the first aspect of the invention may be grown directly by the method described in the application of UK GB0922449.4 and provisional application U.S. serial No. 61/289282, the full disclosure of which is incorporated here by reference. More specifically, the method includes providing a substrate; providing a gas source; and enabling homoepitaxial synthesis of diamond on the substrate; and environment synthesis contains nitrogen atomic concentration from about 0.4 ppm to about 50 ppm; and when the gas source contains: (a) the atomic ratio of hydrogen (Hffrom about 0.4 to about 0.75; (b) the atomic percentage of carbon, Cffrom about 0.15 to about 0.3; (C) atomic ratio of oxygen Offrom about 0.13 to about 0.4; when Hf+Cf+Of=1; thus the ratio of the atomic fraction of carbon atomic fraction of oxygen, Cf:Ofsatisfies the relationship about to 0.45:1<Cf:Of< approximately 1.25:1; and the gas source contains hydrogen atoms are added in the form of hydrogen molecules H2when the atomic fraction of the total number present of hydrogen atoms, is of ikorodu and carbon between the 0.05 and 0.4; while atomic fraction of HfCfand Ofrepresent a fraction of the total number of atoms of hydrogen, oxygen and carbon present in the gas source. This method of growing CVD diamond material will be named in the description "CVD-method of cultivation with the addition of oxygen". Typically it leads (depending on the concentration of nitrogen) for the provided CVD diamond material, which is a colorless, nearly colorless or has a slight brown staining.

The color of the irradiated diamond material is a combination of the original color, if any, provided diamond material, and orange introduced stages of irradiation and annealing for introducing chains of vacancies. Other impurities, which could make the color of the provided diamond material can be in certain embodiments of lean. For example, uncompensated boron (isolated boron) by itself can give a diamond material blue color. For some variants of realization of atomic concentration [B] of boron in the provided diamond material is less than 5×1015cm-3.

It is known that if the diamond material is uncompensated boron, it is possible to compensate for irradiation to introduce isolated vacancies, and isolated vacan the AI combined with boron so, neither Bohr nor compensating its isolated vacancies do not attach the diamond material of any color. Therefore, in some embodiments of according to the present invention, if the diamond material actually contains uncompensated boron (for example, at a concentration of >5×1015cm-3), the stage of the irradiation can be carried out so as to introduce a fairly isolated vacancies not only to compensate for the boron, but also to achieve a given concentration [VT] isolated vacancies. The level of additional exposure required to compensate for the boron could be determined by the expert in this field of technology empirically. Thus, in some embodiments of the method according to the invention uncompensated boron is present in the provided diamond material in a concentration of >5×1015cm-3stage irradiation introduces in the diamond material is fairly isolated vacancies, so that the total concentration of [VT] isolated vacancies in the irradiated diamond material after isolated vacancies were used for compensation of boron, was at least more than 0.5 ppm, or 50% higher than the concentration [Ns0] in ppm in the provided CVD diamond material. The level of additional exposure required to compensate for the boron could be determined the Yong empirically specialist in this field of technology. The total content of boron in the material can be quantified using well-known specialist methods. For example, to determine the total concentration of boron can be used mass spectrometry of secondary ions (SIMS). Uncompensated boron can be detected using either induced absorption measured in the infrared part of the spectrum of the diamond, or the measurement of the Hall effect or transport of charge carriers known to the expert.

Typical concentration [Ns0] in ppm in the provided CVD diamond material will remain essentially unchanged under irradiation (stage (ii) of the methods according to the invention). It will change depending on the stage of annealing (stage (iii) of the methods according to the invention), as explained in this description later.

Provided CVD diamond material used in the method according to the first aspect of the present invention, may preferably have at least about 50%, alternatively at least about 80%, alternatively at least about 90%, alternatively at least about 95% of the volume of synthetic CVD diamond material, formed from a single sector growth. This single growth sector preferably is a {100}or {110}-sector growth. Material a single sector growth preferably who meet the levels of N s0within ±10% from the average of more than about 50% of the total sector growth, alternatively more than about 60% of the total sector growth, alternatively more than about 80% of the sector's volume growth. The use of prescribed synthetic CVD diamond material that has been grown from a single sector growth, profitable, because CVD diamond material will have less of surfaces with different crystallographic orientations (which are the surfaces corresponding to different growth sectors). Surfaces with different crystallographic orientations are sharply distinguished absorption of impurities of nitrogen, and therefore the synthetic CVD diamond material containing more growth sectors, tend to be more undesirable areas with different color due to different concentrations of Ns0in various growth sectors.

The color of the diamond material, painted using the method pokerstove processing, represents the color of the diamond material before pokerstove processing, combined with the influence on the color of any defect, obtained during pokerstove processing. In accordance with the method according to the present invention we have found that if we apply specific processing after CVD-cultivation, we can give the diamond the material, the orange color. May be permitted levels of yellow or brown color is from low to moderate, and treated diamond (after irradiation and annealing according to the invention) will still look orange because orange staining, given pokerstove processing, has a saturation (S*, as described below) from moderate to high and the lightness (L*, as described below) from moderate to light, and therefore is able to mask the yellow or brown with low to moderate levels in the provided CVD diamond. For certain variants of realization according to the invention, we start with the provided CVD diamond, which has a minimum color or not have it at all, i.e. is essentially colorless; for other variants of realization according to the invention, we start with the provided diamond material that has some color, usually yellow or brownish tint. For example, some implementation options to get light orange diamond material which has a low value With* and/or high L* values (for example, With*<10 and/or L*>65), it would be necessary to start with a colorless or pale yellow material.

In accordance with the method of the present invention stage irradiation introduce isolated vacancies total concentration of [VT]that is in me is greater as the greater of (a) 0.5 ppm and (b) 50% higher than the concentration [NS0] in the provided diamond material. Concentration [VT] isolated vacancies is given by the sum [V0] and [V-], where [V0] is the concentration of isolated neutral vacancies, [V-] is the concentration of negatively charged isolated vacancies, both in ppm. Both concentration [V0] and [V-] determine on the basis of absorption GR1 ND1 and the absorption spectrum of the irradiated diamond as described below. It is possible that the above-mentioned irradiation could enter vacancies in other forms, for example, as a pair or possible isolated positive vacancies. The inventors did not observe any obvious signs in the material, which could be associated with such defects, but do not exclude this possibility. In certain embodiments of the invention, the total concentration of [VT] isolated vacancies is greater than (a) 0.5 ppm and (b) 50% higher than the concentration [NS0] in the provided diamond material. For example, the total concentration [VT] isolated vacancies may be at least 0,7 ppm, or at least to 0.9 ppm, or at least 1.0 ppm greater than the concentration [NS0] in the provided diamond material.

In General, the greater the dose, the greater the number of created isolated the job. The number of isolated vacancies may depend not only on the period of irradiation dose, but also on the number and nature of defects in the provided CVD diamond material. Therefore, to calculate the desired dose of electron radiation also calculate the rate of receipt of isolated vacancies for these irradiation conditions, as will be known to specialists in this field of technology.

Concentration [VT]obtained under fixed experimental conditions and duration of exposure can influence such factors as the temperature of the diamond, the beam energy, beam density, and even the properties of the original diamond. The irradiation is typically carried out with the sample installed in the environment ~300 K, with only minimal increase in temperature at the time of deciding on the dose of irradiation (for example, less than 100 K). However, factors such as the beam energy and beam density, can lead to warming up of the sample. Preferably, the sample support as possible cold (even advantageous in some circumstances cryogenic cooling at 77 K)to ensure the ability of high-dose radiation exposure without compromising temperature control and, thereby, to minimize the duration of exposure. This is advantageous from a production considerations. Calibration of the applied dose in relation to Wakan is the s, received provided for a specific diamond, used to meet these limits imposed concentration [VT], will form part of specialist prior to implementation of the method according to the present invention. Such calibration techniques are routine to a person skilled in this technical field.

A larger sample could be rotated and irradiated with two or more parties in order to enter the vacancy on the entire thickness of the diamond material.

Not necessarily, before the first stage of irradiation provided diamond material may be annealed in the temperature range 1400-2500°C.

Stage (iii) of the methods according to the invention includes annealing the irradiated diamond material at a temperature of at least 700°C. and at most 900°C for a period of at least 2 hours. The action that this stage of annealing has on isolated vacancies in the irradiated diamond material, depends on whether and how the number of defects Ns0in the irradiated diamond material. If defects Ns0are present in the diamond material, initially annealing at a temperature of from 700°C to 900°C to form NV-centers, each NV center is the sum of Ns0-defect single isolated vacancy. With what you learn when Ns0-defects are present, mainly after formed the maximum number of NV centers, begin to form chains of vacancies. However, not all Ns0-defects converted to NV-centers, which seems to be caused by the distribution of some of the Ns0-defects. When the concentration of NV-centers has reached saturation, any isolated vacancies that were not used in the formation of NV centers are available for Association between the formation of chains of vacancies. These chains of vacancies shall be submitted giving the orange color of the treated diamond material according to the present invention. Therefore, in the methods according to the present invention, the irradiation of the provided CVD diamond material to introduce isolated vacancies V in at least part of the provided CVD diamond material is such that the total concentration [VT] isolated vacancies in the irradiated diamond material was at least more than (a) 0.5 ppm and (b) 50% higher than the concentration [Ns0] in ppm, so there is a sufficient excess of isolated vacancies in excess of those that join to form a single NV-centers that are available to bind to each other to form chains of vacancies.

If in the provided CVD diamond is the material of the N s0-defects (and provided that no other uncompensated element, such as boron present), in the implementation stage (iii) annealing in the methods according to the invention isolated vacancies formed during the stage of irradiation, will begin to be grouped in a chain of vacancies immediately.

Any isolated vacancies remaining in the crystal lattice, usually lead to flattening of the UV/visible spectrum, which typically is the result of more grey diamond material. Therefore, for some variants of realization of the concentration of isolated vacancies after completion of the annealing process is greatly reduced and can be reduced to a minimum. For some variants of implementation, after the annealing process, the total concentration of isolated vacancies is <0.3 ppm, optional <0,2, optional <0,1, or optional <0,05 ppm, stone weight of 0.5 carats (ct) with a round brilliant cut (rbc).

For many implementation options is optimal annealing, which will give the highest conversion of isolated vacancies in a possible chain of vacancies. Such implementations can lead to a bright orange material with a high value With the*typical*>20.

Though without manifestations in the visible part of the spectrum as such, the increase in absorption with center at 250 nm which is characteristic for orange coloring and saturation levels of gradation orange color with respect to this characteristic. Therefore, a measure of the concentration of chains of vacancies is the absorption at 250 nm. For some variants of realization after irradiation and annealing, for diamond stone weight 0.5 CT round brilliant cut, the absorption at 250 nm, as measured at room temperature is >5 cm-1optional >7 cm-1optional >10 cm-1when the spectra scale to 0 cm-1at 800 nm. Professionals in this area of engineering is known that the concentration of vacancies will need to change for the diamond stones with different path lengths, to obtain the coefficients of absorption.

An additional advantage of the irradiation of CVD diamond material is usually that the color of the material will be more resistant to low-temperature annealing and UV light (radiation with an energy of at least 5.5 eV) compared with untreated CVD diamond. This stabilization effect is discussed in the application form UK number 0911075.0 and provisional application U.S. number 61/220663, both filed on June 26, 2009, and in the application of UK number 0917219.8 and provisional application U.S. number 61/247735, both filed October 1, 2009, the full disclosure of which is incorporated here by reference.

In some embodiments of the invention provided diamond material exhibits a measurable difference is their in at least one of its absorption characteristics in the first and second States, moreover, the first state occurs upon exposure to radiation with an energy of at least 5.5 eV (typically UV light), and the second state - after the heat treatment at a temperature of 798 K (525°C), and after stages of irradiation and annealing methods according to the invention the change values* color saturation between the diamond material in the first and second States is reduced by at least 0.5 in. This color stabilization can sometimes occur after simple exposure. Optional stages after irradiation and annealing methods according to the invention the change in the value S* of the diamond material in the above-mentioned first and second conditions is less than 1.

Generally, stage annealing is carried out after completion of irradiation. However, it is also envisaged that it may be some overlap between the processes of irradiation and annealing, for example, stage annealing may be started before completion of the exposure, or the two processes may be carried out, and started over, essentially at the same time.

Typically, the annealing is carried out in an inert atmosphere, e.g. argon atmosphere or in vacuum. The annealing is typically carried out at a pressure of <100 mbar.

The present invention also is diamond material, when it is manufactured by the method according to the first aspect of the invention.

The second and the aspect of the present invention is CVD diamond material, who, being in the form of stone 0.5 CT with rbc, qualifies as fantasy orange.

The terminology "fancy orange diamond material" is defined as diamonds, which have a clear and distinct orange color (Diamond grading ABC The Manual, the author Verena Pagel-Theisen, publishers Rubin & Son, Belgium, 9th edition, 2001, page 67).

The third aspect of the present invention is CVD synthetic single crystal diamond having a hue angle in the range 69-90 for the equivalent diamond weight of 0.5 carats of round brilliant cut (rbc).

The perceived color of any particular diamond stone depends on the size and cut of the diamond. Therefore, where reference is made to the hue angle (which determines the color or any color, in this area usually indicate this is a standard size, usually 0.5 carats, and the standard cut of the diamond stone, usually round brilliant cut (often known as RBC or rbc). For any given diamond stone, whether it is larger or smaller than 0.5 carats or with a round brilliant cut or any other facet, there are models for the correction color to the color for the standard size and cut. Therefore, the provided diamond material used in the method according to the first aspect of the invention, can have any size or what Granma, but the color settings where indicated, adjusted to the parameters for the equivalent material of the diamond stone with a typical size of 0.5 CT and standard round brilliant cut, for comparison with the specified values.

The embodiments of the invention can have one or more of the following color characteristics for the equivalent of the diamond stone weight 0.5 CT round brilliant cut (RBC).

Table 1
DescriptionRange
The hue angle α68°-90°
optional 69°-85°
optional 70°-80°
The saturation C*2-70
optional 3-65
optional 4-60
The lightness L*>45
optional >50
optional >55

The material according to this invention can be distinguished from newly grown orange material that has not been subjected to processing, on the grounds that entered during irradiation. They include small, but measurable signs of absorption or photoluminescence (PL), as measured at a temperature of 77 K or lower is. For example, can be strengthened signs at 741 nm and 673 nm, 575 nm, or 503 nm.

The color of the irradiated and annealed diamond can be described in a conventional manner using a Chromaticity Coordinate CIE L*a*b*". The use of Chromaticity Coordinate CIE L*a*b* in the diamond described in WO 2004/022821, the full disclosure of which is included here by reference. The values a* and b* to be applied on the graph on the x - and y-axes, and the hue angle measured from the positive axis a* to the positive b axis*. Thus, the hue angle more than 90° and less than 180° is in the upper left quadrant of the a*b*-graphics. In this scheme to describe the color value L* represents the lightness, and the fourth coordinate With* represents saturation.

The perceived color of an object depends on the spectrum transmittance/absorption of the object, the spectral power distribution of the light source and the sensitivity of the observer's eye. The chromaticity coordinates CIE L*a*b* (and therefore the angles of the colour tone)presented here were derived is described below by. Using a standard spectrum of the source D65 illumination and standard (red, green, and blue) curves of the sensitivity of the eye (G. Wyszecki and W. S. Stiles, John Wiley, New York-London-Sydney, 1967), chromaticity coordinates CIE L*a*b* plane-parallel plate of diamond have been deduced from its spectrum bandwidth using the-W to the following relationships, between 350 nm and 800 nm with a step of 1 nm:

Sλ= transmittance at a wavelength ofλ

Lλ= spectral power distribution of the light source

xλ= characteristic sensitivity of the eye to red

yλ= characteristic sensitivity of the eye to green

zλ= characteristic sensitivity of the eye to the blue color

X=∑λ[SλxλLλ]/Y0

Y=∑λ[SλyλLλ]/Y0

Z=∑λ[SλzλLλ]/Y0

where Y0=∑λyλLλ

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 Y/Y0X/X0and Z/Z0should be used modified versions of these equations. Modified options, refer to the technical report prepared by the International Commission on illumination (Commission Internationale de L'éclairage) (Colorimetry (1986)).

The default path is the application of the coordinates a* and b* in a graph with a*corresponding to the x-axis, and b*correspond to what they y-axis. Positive values of a* and b* respectively correspond to the red and yellow components of the color tone. Negative values of a* and b* respectively correspond green and blue components. Then the positive quadrant of the graph covers the color hues ranging from yellow through orange to red, with values of saturation (C*), defined by the distance from the origin.

You can predict how the coordinates a*b* diamond with the absorption spectrum will change with variations in the length of the optical path. To do this, first you need from the measured absorption spectrum deduct the losses. Then the absorption scale for an amendment to another path, and then re-add the reflection losses. Then, the absorption spectrum can be converted in the transmission spectrum, which is used to derive the coordinates of the CIE L*a*b* for the new thickness. This way you can model the dependence of the hue, saturation and lightness of the length of the optical path for understanding how color diamond with these properties absorption per unit thickness will depend on the length of the optical path.

L*, lightness, forms the third dimension of the color space CIE L*a*b*. It is important to understand how the lightness and saturation vary as the length changes, optionscom the way to diamond with specific properties of optical absorption. The method described in the previous paragraph, can also be applied to predict how the coordinates L** diamond with the spectrum of the absorption coefficient depends on the length of the optical path.

The value of C* (saturation) can be subdivided into intervals of saturation in units 10C* assigned descriptive notation, as shown below.

0-10 weak

10-20 weak-moderate

20-30 moderate

30-40 moderate-strong

40-50 strong

50-60 strong-very strong

60-70 is very strong

70-80+ very very strong

Similarly, the values of L* can be subdivided into intervals values as follows:

5-15 very very dark

15-25 a very dark

25-35 dark

35-45 medium/dark

45-55 average

55-65 light/medium

65-75 light

75-85 very bright

85-95 very very bright

There are four basic hues, defined according to the following combinations of lightness and saturation:

Bright: bright and high saturation.

Yellow: bright and low saturation.

Deep: high saturation and dark,

Dim: low saturation and dark.

The preferred angle of hues and values a*, b*, C* and L* provide a quantitative measure of the quality and colour of synthetic CVD diamond material of the present invention. This color is a Hilbert properties are advantageous, because they give the diamond orange color, and can be used for decorative purposes, such as precious stones for jewelry, or for use as a colored filters, or the like.

For all samples used in this description, the height of the absorption peaks shown in this description, measured using recorded at room temperature absorption spectrum in the UV/visible region of the synthetic CVD diamond material.

All taken at room temperature absorption spectra, referred to here were recorded with a spectrometer Perkin Elmer Lambda-19. Range of reflection losses created using tabular data on the refractive indices and the standard expressions for the reflection losses for plane-parallel plate. The refractive index was determined by the equation of Peter [Z. Phys., volume 15 (1923), pp. 358-368)], and then withdrew the magnitude of the reflection losses using the standard Fresnel equations. Range return loss subtracted from the measured data acquisitions, and from the resulting spectrum deduced spectrum of the absorption coefficient for the sample. Data on the absorption coefficient was shifted so that the absorption coefficient was applied to zero at 800 nm.

Concentration in ppm given in this description for various defects, [NV+/- ] and [V0/-], can be calculated with known standard by integrating the square of the peaks in the absorption spectrum of the diamond, usually recorded at liquid nitrogen temperatures, and using published factors for comparison to calculate the concentration. For concentrations of NV-centers and isolated vacancies spectra mainly get at 77 K using liquid nitrogen to cool the sample, since at this temperature appear sharp peaks at ~741 nm and ~394 nm, attributed to V0and V-and at 575 nm and 637 nm, respectively ascribed to defects NV0and NV-. The coefficients used for the calculations of the concentrations of NV-centers and isolated vacancies in this description, are what the author has described G. Davies in the publication Physica B, vol 273-274 (1999), pages 15-23, as further shown below in Table 2.

Table 2
Defect [designation]Calibration (MeV cm-1)
[V-] ND1AND1=(4,8±0,2)×10-16[V-]
[V0] GR1AGR1=(1,2±0,3)×10-16[V0]
[NV-][NV0]ANV0=(1,4±0,35)×10-16[NV0]

In Table 2, the symbol "A" represents the integral absorption (MeV cm-1in the zero phonon line of the transition, measured at a temperature of 77 K, the absorption coefficient in cm-1and photon energy in MeV. Concentration specified in cm-3.

Provided CVD diamond material used in the method according to the present invention, as well as irradiated CVD diamond material obtained by the method according to the present invention, may be or not be part of a larger fragment (piece) of the diamond material. For example, irradiation may be subjected to only a part of a larger fragment of the diamond material, and/or only part of a larger fragment of the diamond material can be defined absorption characteristics. As would be clear to the expert in this field of technology, multiple layers could also be subjected to irradiation and/or would have required characteristics of absorption, so that the provided CVD diamond material used in the method according to the invention may form part, for example, one or multiple layers of a larger fragment of the diamond is the material. It is well known that the penetration depth of the radiation depends on the energy of the radiation. Thus, in preferred embodiments of the radiation energy is chosen so that the radiation penetrates only part of the depth of the CVD diamond material. This means that isolated vacancies could be introduced only penetrated by the radiation a portion irradiated CVD diamond material, and therefore, it is penetrated by the radiation part of the CVD diamond material would be used "diamond material"formed by the method according to the present invention.

Where provided CVD diamond material is only part of a larger fragment of the diamond material, as discussed above, only the provided CVD diamond material may have advantageous optical properties described for certain variants of the invention. For example, the upper or subsurface layer or layers of the large fragment of CVD diamond material may be orange. Where any other neoregelia layers are essentially colorless, the color is just a larger slice of the diamond material is determined by the orange(s) layer(s).

In some embodiments of the invention at least 50%or at least 60%or at least 70%or at least 80%or at least 90%, or su is estu all the diamond stone may have essentially the same color.

In other embodiments of the invention the diamond stone can contain layers or pockets of the diamond material with the same color.

Now will be described, as an example, the embodiments of the invention with reference to the accompanying drawings, in which:

Figure 1, which was mentioned above, is a block diagram that shows the routes in the methods according to the invention to obtain an orange diamond material;

Figure 2 represents the absorption spectra in the UV/visible region, measured at room temperature for examples 1 and 2, after irradiation and annealing; and

Figure 3 represents the absorption spectra in the UV/visible region, measured at a temperature of 77 K for examples 3, 5 and 6, after irradiation and annealing.

EXAMPLES

Diamond VDT-substrate suitable for synthesizing single-crystal CVD diamond according to the invention, cut by laser, sollipulli before the substrates are polished to minimize subsurface defect so that the defect density was below 5×103/mm2and usually below 102/mm2. Polished square VDT plates with dimensions of 3.6 mm × 3.6 mm, with a thickness of 500 μm, with all faces {100}, with a surface roughness RQat this stage, less than 1 nm, found on the refractory metal is the lawsuit and was placed in the reactor for growing CVD diamond.

Growth stage

1) a Reactor for growing CVD diamond pre-equipped working place of use cleaners that reduce the number of unintentional impurities in the incoming gas stream to below 80 parts per billion (ppb).

2) carried out the etching in situ oxygen plasma using flow About2/Ar/N2in relation 50/40/3000 sccm (standard cubic centimeters per second) and the substrate temperature of 760°C.

3) This processing without interruption transferred to hydrogen etching, removing About2from the gas stream.

4) This processing is transferred in the process of growing the addition of a carbon source (in this case, CH4and alloying gases. In these examples CH4flowing with a flow rate of 165 sccm, nitrogen at different levels for different samples was present in the process gas supplied from a calibrated source, for example, from a source containing 100 ppb N2or as the air in the Ar or N2in N2and in some instances in the process gas was also present On the2as shown in Table 3.

Table 3
ExampleDoping nitrogen in the process gas (ppm) The flow of oxygen in the process gas (ppm)
1 and 20,70
31,89160
4-61,113657

5) Upon completion of the growth period, the substrate was removed from the reactor, and a layer of CVD diamond is separated from the substrate using laser cutting and methods mechanical polishing.

6) It gave CVD sample, which had a typical size of ~3,1×5×5 mm

This grown CVD diamond is a "stipulated diamond", as defined in the claims of this application.

Examples were subjected to electron irradiation using electron beam with an energy of 4.5 MeV at 50%the width of the scan and 20 mA beam current using a source of electron beam, such as an existing company Isotron PLC. The irradiated diamond samples has established in India a water cooled copper block to prevent heating of the samples above 350 K. Then, the samples were annealed in a tube furnace Elite (model THS 16/50/180-2416CG and 27160/T). Usually for making orange diamond material used dose of 5.8×1018e-/cm2(equivalent to 6 hours of irradiation of the electron beam with which the Nergy of 4.5 MeV at 50%the width of the scan and 20 mA beam current), followed by 8-hour annealing at 800°C.

Table 4 shows the chemical composition of the environment CVD-cultivation, the concentration of [Ns0] in the provided diamond material, the absorption coefficient at 350 nm and 510 nm, and the color of the provided diamond material, the irradiation dose, the concentration of vacancies after irradiation, the duration and temperature of annealing, the color of the diamond material after irradiation and annealing, color characteristics, the concentration of [NV], [V0] and [V-], and the absorption at 250 nm, related to the chains of vacancies, all after irradiation and annealing. The results in table 4 include not only examples that fall within the scope of the present invention, but also a number of comparative examples. For example, if the dose is not high enough, the number of isolated vacancies available for Association with the formation of chains annealing, regardless of the duration of annealing, will not be large enough for the formation of significant concentrations chains vacancies; in the case of comparative examples 2 and 6, which are outside the scope of the present invention, since the concentration of isolated vacancies introduced during the stage of irradiation is less than the value of more than (a) 0.5 ppm and (b) 50% higher than the concentration [Ns0], and the absorption at 250 nm in the treated sample sostav the em < 5 cm-1. This is also illustrated by the involvement of Figure 2, which is taken at room temperature (CT) absorption spectrum in the UV/visible region for examples 1 and 2, after irradiation and annealing. This figure shows a strong absorption at 250 nm for example 1, indicating the presence of chains of vacancies, whereas in example 2, the absorption in the region of 250 nm is less than 5 cm-1showing a low concentration of formed chains of vacancies. Similarly, we found that if the duration of the annealing is not sufficiently long, then the total concentration of isolated vacancies remaining in the treated sample is >0.3 ppm; in the case of comparative example 5, which annealed only in for 1 hour and leads to the diamond material with grey staining, compared to orange made in example 4, which represents a sample of the diamond material is identical to example 5 with respect to composition and exposure, but annealed for a longer time.

Figure 3 shows the UV/visible spectra recorded at 77 K after irradiation and annealing, and illustrates, for example, 3 strong absorption at 250 nm and the absence of residual peaks at 741 nm or 394 nm, indicating that essentially all of the isolated vacancies were eliminated by annealing. Figure 3 is e illustrates why comparative example 5 (which was subjected to annealing with insufficient duration) looks gray after irradiation and annealing, as there are peaks at 741 nm and 394 nm, indicating the presence of isolated vacancies, as well as at 575 nm and 637 nm, indicating the presence of NV-centers. Similarly, Figure 3 illustrates why the comparative example 6 (which was subjected to an insufficient dose) looks pale pink, because there are peaks at 575 nm and 637 nm, indicating the presence of NV-centers, a small residual concentration of isolated vacancies, and a weak absorption at 250 nm, indicating a low concentration of chain vacancies.

All samples orange diamond according to the invention (examples 1, 3 and 4) show a strong absorption around 250 nm. This absorption appears to be due to the presence of chains of vacancies. For example, the measured absorption at 250 nm is >5 cm-1for both samples 1 and 3, whereas for the comparative example 2, it is <5 cm-1.

As noted above, an additional advantage irradiation of CVD diamond material is that usually the color of the material will be more resistant to low-temperature annealing and UV light compared with untreated CVD diamond. We found that when naked is evanie sample 1 change the value With the* between the two States was < 1, which illustrates this advantage.

1. Monokristallicheskij CVD synthetic diamond material with the concentration of isolated vacancies <0.3 million-1moreover , this single-crystal CVD synthetic diamond material has one or both of the following characteristics for the equivalent diamond weight of 0.5 carats of round brilliant cut (RBC):
(i) gradation of color - fancy orange; and
(ii) the following color characteristics

DescriptionRange
The hue angle α68°-90°
The saturation S*2-70
The lightness L*>45

2. Single crystal CVD synthetic diamond material according to claim 1, for the equivalent of the diamond stone weight 0.5 CT round brilliant cut absorption in the region of 250 nm measured at room temperature is >5 cm-1.

3. Single crystal CVD synthetic diamond material according to claim 1, the change in saturation* color of the diamond material in the first and second States is less than 1, and the first state has places which upon exposure to radiation with an energy of at least 5.5 eV, and the second state - after the heat treatment at 798 K (525°C).

4. Jewelry containing single-crystal CVD synthetic diamond material according to any one of claims 1 to 3, and a frame for single-crystal CVD synthetic diamond material.

5. Diamond gemstone with round brilliant cut containing single-crystal CVD synthetic diamond material according to any one of claims 1 to 3.

6. A method of manufacturing single-crystal CVD synthetic diamond material according to any one of claims 1 to 3, containing (i) predusmatriva single crystal diamond material that has been grown by the CVD method and has a concentration of single substitutional nitrogenless than 5 million-1; (ii) irradiation provided CVD diamond material in order to introduce isolated vacancies V in at least part of the provided CVD diamond material so that the total concentration of isolated vacancies [VT] in the irradiated diamond material was at least more of (a) 0.5 million-1and (b) 50% higher than the concentration ofmillion-1in the provided diamond material, and (iii) annealing the irradiated diamond material to form chains of vacancies of at least some of the entered isolated vacancies, from the IG carried out at a temperature of at least 700°C. and at most 900°C for a period of at least 2 h, and at this stage of irradiation and annealing to reduce the concentration of isolated vacancies in the diamond material, due to which the concentration of isolated vacancies in irradiated and annealed diamond material is <0.3 million-1.

7. The method according to claim 6, the absorption coefficients at 350 nm and 510 nm for the provided diamond material is less than 3 cm-1and 1 cm-1respectively.

8. The method according to claim 6, while the atomic concentration [In] boron in the provided diamond material is less than 5·1015cm-3.

9. The method according to claim 6, while uncompensated boron is present in the provided diamond material in a concentration of >5·1015cm-3stage (ii) radiation enters into the diamond material sufficiently isolated vacancies, so that the total concentration of isolated vacancies [VT] in the irradiated diamond material after isolated vacancies were used for compensation of boron, was at least more of (a) 0.5 million-1and (b) 50% higher than the concentration ofmillion-1in the provided diamond material.

10. The method according to claim 6, while the provided diamond material is irradiated with two or more parties.

11. The method according to claim 6, at least 50% of the provided CVD diamond material formed from the different sectors of growth.

12. The method according to claim 6, in this case, after steps (ii) and (iii) irradiation and annealing, the absorption in the region of 250 nm irradiated and annealed diamond material, measured at room temperature is >5 cm-1.

13. The method according to claim 6, while the provided diamond material has a measurable difference in at least one of its absorption characteristics in the first and second States, the first state occurs upon exposure to radiation with an energy of at least 5.5 eV, and the second state - after the heat treatment at 798 K (525°C), and after stages of irradiation and annealing changing values* color saturation between the diamond material in the above-mentioned first and second conditions is reduced by at least 0,5 compared with changing values* color saturation between the diamond material in the above-mentioned first and second conditions for the provided diamond material.

14. The method according to claim 6, while stages after irradiation and annealing the change in saturation* color of the diamond material in the first and second States is less than 1, and the first state occurs upon exposure to radiation with an energy of at least 5.5 eV, and the second state - after the heat treatment at 798 K (525°C).

15. The method according to claim 6, while at the stage of exposure provided diamond material from Haut in the temperature range of 1400°C.-2500°C.

16. The method according to claim 6, in this stage (iii) annealing carried out after the completion of stage (ii) exposure.



 

Same patents:

FIELD: construction.

SUBSTANCE: electrodes in the form of a system of parallel strings are applied onto two flat-parallel faces of the crystal, which are aligned at the angle of z+36° to the polar axis, wire platinum contracts are connected to electrodes, the assembled cell is placed into a furnace and heated to temperature of phase transition - Curie temperature under action of a heterogeneous electric field, as a result of which two oppositely charged domains of equal volume are formed with a flat domain-to-domain border.

EFFECT: invention makes it possible to change from traditionally used piezoceramic elements of deformation to single-crystal bidomain elements of precise positioning on the basis of single crystals of ferroelectrics with high Curie temperature, which do not have creep and hysteresis.

2 cl, 2 dwg, 1 ex

FIELD: chemistry.

SUBSTANCE: method of forming polydomain ferroelectric monocrystals with a charged domain wall involves using a workpiece in form of plate of ferroelectric monoaxial monocrystal of the lithium niobate and lithium tantalate family, which is cut perpendicular to the polar axis, one of the surfaces of which is irradiated with ion flux to form high concentration of point radiation defects in the surface layer, which results in high electroconductivity of the layer, after which an electric field is formed in the plate, directed along the polar axis, the polarity and value of which enable formation of domains on the surface of the plate which is not exposed, and their growth deep into the plate in the polar direction up to the boundary of the layer with high conductivity, which leads formation of a charged domain wall with an irregular shape, wherein the depth of the layer is determined by the value of the energy and dose of ions, and the shape of the wall is determined by the value of the electric field formed.

EFFECT: invention enables to form a charged domain wall, having an irregular three-dimensional shape with given geometric parameters, lying at a given depth in a monocrystalline ferroelectric plate without heating the plate or cutting a workpiece for making the plate.

4 cl, 7 dwg

FIELD: process engineering.

SUBSTANCE: invention relates to processes used in operation at high pressure and modifying substances physically. Proposed method comprises placing diamond in reaction cell in pressure transmitting medium, increasing pressure in reaction chamber and it cooling. Note here that thermal treatment is carried out at temperature increase rate of 10-50°C/s and at 2000-2350°C by passing electric current via heater in cell from programmed power supply source with due allowance for temperature relaxation in said cell in heating. For this, note also that temperature relaxation constant is defined. Said cell is cooled after heating by switching off power supply in forming short diamond heating pulse in temperature range of over 2000°C with diamond total stay time smaller than 30 seconds. Allowance for temperature relaxation in said cell in heating for heating rate Vt and pre-definition of cell temperature relaxation constant τ is made by setting in said programmable power source the maximum temperature of heating to τVT above maximum treatment temperature of 2000-2350°C.

EFFECT: changing colour of low-grate natural diamond without notable graphitisation, high-quality gem diamonds.

2 cl, 5 dwg, 3 ex

FIELD: physics.

SUBSTANCE: inside a diamond, in the region free from optically impermeable irregularities, an image is formed, which consists of a given number of optically permeable elements of micrometre or submicrometer size, which are clusters of N-V centres which fluoresce in exciting radiation, wherein formation of clusters of N-V centres is carried out by performing the following operations: treating the diamond with working optical radiation focused in the focal region lying in the region of the assumed region where the cluster of N-V centres is located, while feeding working ultrashort radiation pulses which enable to form a cluster of vacancies in said focal region and which provide integral fluence in said focal region lower than threshold fluence, where there is local conversion of the diamond to graphite or another non-diamond form of carbon; annealing at least said assumed regions where clusters of N-V centres are located, which provide in said regions drift of the formed vacancies and formation of N-V centres, grouped into clusters in the same regions as the clusters of vacancies; controlling the formed image elements based on detection of fluorescence of N-V centres by exposing at least regions where image elements are located to exciting optical radiation, which enables to excite N-V centres and form a digital and/or a three-dimensional model of the formed image. Images formed in diamond crystals from clusters of N-V centres are visible to the naked eye, by a magnifying glass and any optical or electronic microscope.

EFFECT: image from a cluster of N-V centres is inside the crystal, cannot be removed by polishing and is therefore a reliable diamond signature and reliable recording of information without destroying or damaging the crystal itself.

46 cl, 3 dwg

FIELD: chemistry.

SUBSTANCE: invention can be used in magnetometry, quantum optics, biomedicine and information technology. Cleaned detonation nanodiamonds are sintered in a chamber at pressure 5-7 GPa and temperature 750-1200°C for a period time ranging from several seconds to several minutes. The obtained powder of diamond aggregates is exposed to laser radiation with wavelength smaller than 637 nm and diamond aggregates with high concentration of nitrogen-vacancy (NV) defects are selected based on the bright characteristic luminescence in the red spectral region. In the obtained diamond structure, about 1% of carbon atoms are substituted with NV defects and about 1% of carbon atoms are substituted with single nitrogen donors.

EFFECT: aligned blocks of nanodiamonds obtained using the invention have quasi-crystalline properties, which makes investigation and identification thereof easier; the aggregates can also be ground to obtain diamond nanocrystals having NV defects.

2 cl, 5 dwg

FIELD: chemistry.

SUBSTANCE: method involves step-by-step treatment of diamonds in an autoclave at high temperature and pressure, including a step for cleaning with a mixture of nitric acid and hydrogen peroxide and a step for cleaning with a mixture of concentrated nitric, hydrochloric and hydrofluoric acids under the effect of microwave radiation. After the step for cleaning with nitric acid and hydrogen peroxide, the diamonds are treated under the effect of microwave radiation with hydrochloric acid in gaseous phase at temperature 215-280°C for 15-300 minutes. Further, the diamonds are treated with distilled water at temperature 160-280°C for 5-30 minutes in an autoclave in liquid phase. At the step for cleaning with a mixture of nitric acid and hydrogen peroxide, treatment is carried out with the following volume ratio of components: nitric acid and hydrogen peroxide 4-10:1-3, respectively, at temperature 215-280°C for 15-540 minutes in liquid phase in a system with external heating or in a gaseous phase under the effect of microwave radiation. At the step for cleaning with a mixture of concentrated nitric, hydrochloric and hydrofluoric acids, treatment under the effect of microwave radiation is carried out with the following volume ratio of components: nitric, hydrochloric and hydrofluoric acid 1-6:1-6:1-3, respectively, in gaseous phase at temperature 215-280°C for 15-300 minutes.

EFFECT: invention increases the effectiveness of the process of cleaning diamonds larger than 4,0 mm with high efficiency of the equipment used.

3 cl, 3 dwg, 2 tbl, 1 ex

FIELD: metallurgy.

SUBSTANCE: procedure consists in ion-energy-beam processing diamonds with high power ion beam of inert chemical element of helium with dose of radiation within range from 0.2×1016 to 2.0×1017 ion/cm2 eliminating successive thermal annealing.

EFFECT: production of amber-yellow and black colour of diamond resistant to external factors at significant reduction of material and time expenditures of process of diamond upgrading.

1 dwg, 2 ex

FIELD: metallurgy.

SUBSTANCE: procedure for radiation of minerals in neutron flow of reactor in container consists in screening radiated minerals from heat and resonance neutrons. Composition of material and density of the screen is calculated so, that specific activity of radiated minerals upon completion of radiation and conditioning does not exceed 10 Bq/g. Before radiation contents of natural impurities in radiated minerals can be analysed by the method of neutron activation analysis. Only elements activated with resonance neutrons are chosen from natural impurities of radiated minerals. Tantalum and manganese or scandium and/or iron or chromium are used as elements of the screen. Chromium-nickel steel alloyed with materials chosen from a row tantalum, manganese and scandium are used in material of the screen.

EFFECT: increased protection of product from resonance neutrons activating impurities in minerals.

5 cl, 1 tbl

FIELD: physics.

SUBSTANCE: device for irradiating minerals has a reactor active zone, an irradiation channel, a container and extra slow neutron filter. Inside the container there are slow and resonance neutron filters. The extra slow neutron filter surrounds the container and is fitted in the irradiation zone. A gamma-quanta absorber of the reactor is placed between the container and the active zone of the reactor. A resonance neutron absorber is added to the extra slow neutron filter. The thickness of these absorbers enables to keep temperature inside the container not higher than 200°C during irradiation.

EFFECT: invention increases the possible volume of irradiated specimens and increases efficiency of modifying minerals.

1 dwg

FIELD: metallurgy.

SUBSTANCE: invention relates to industrial production of monocrystals, received from melt by Czochralski method, and can be used during polarisation of ferroelectrics with high temperature Curie, principally lithium tantalate. On monocrystal of lithium tantalate by means of grinding it is formed contact pad, surface of which is perpendicular to optical axis of crystal or at acute angle to it. Monocrystal is located between bottom segmental or laminar platinum electrode and implemented from wire of diametre 0.3-0.6 mm top circular platinum electrode through adjoining to its surfaces interlayers. In the capacity of material of interlayer it is used fine-dispersed (40-100 mcm) powder of crystalline solid solution LiNb1-xTaxO3, where 0.1≤x≤0.8, with bonding alcoholic addition in the form of 94-96% ethyl alcohol at mass ratio of alcohol and powder 1:2.5-3.5. Monocrystal is installed into annealing furnace, it is heated at a rate not more than 70°C/h up to temperature for 20-80°C higher than temperature Curie of monocrystal and through it is passed current by means of feeding on electrodes of polarising voltage. Then monocrystal is cooled in the mode current stabilisation at increasing of voltage rate 1.2-1.5 times up to temperature up to 90-110°C lower than temperature Curie, and following cooling is implemented in the mode of stabilisation of polarising voltage at reduction of current value through monocrystal. At reduction of current value 3.0-4.5 times of its stable value voltage feeding is stopped, after what monocrystal is cooled at a rate of natural cooling-down. Monocrystal cooling up to stop of feeding of polarising voltage is implemented at a rate 15-30°C/h.

EFFECT: method provides increasing of efficiency of monocrystals polarising of lithium tantalate, different by orientation, dimensions and conditions of growing; shaped interlayer provides durable and uniform cohesion of crystal surface to electrodes, and current and voltage stabilisation and fixed rate of crystal cooling in the range of temperature Curie provide guaranteed receiving of transparent, blast-furnace crystals of lithium tantalite without additional defects in the form of cracks and disruptions.

3 cl, 4 ex

FIELD: construction.

SUBSTANCE: electrodes in the form of a system of parallel strings are applied onto two flat-parallel faces of the crystal, which are aligned at the angle of z+36° to the polar axis, wire platinum contracts are connected to electrodes, the assembled cell is placed into a furnace and heated to temperature of phase transition - Curie temperature under action of a heterogeneous electric field, as a result of which two oppositely charged domains of equal volume are formed with a flat domain-to-domain border.

EFFECT: invention makes it possible to change from traditionally used piezoceramic elements of deformation to single-crystal bidomain elements of precise positioning on the basis of single crystals of ferroelectrics with high Curie temperature, which do not have creep and hysteresis.

2 cl, 2 dwg, 1 ex

FIELD: chemistry.

SUBSTANCE: method involves loading starting separate silver chloride and silver bromide salts into a container made of heat-resistant glass, fusing said salts to a given composition of solid solution, growing a monocrystal in a halogenating atmosphere by moving the container in a temperature gradient, cooling the grown crystal to room temperature and removing the crystal from the container; the monocrystal is then heated at a rate of 50-60°C per hour to temperature of 250-270°C, held at said temperature for 1-2 hours, cooled at a rate of 20-25°C per hour to temperature of 100-150°C and then cooled at a rate of 30-40°C per hour to room temperature.

EFFECT: reduced internal stress in the crystalline workpiece, improved optical homogeneity and reduced optical losses.

2 ex

FIELD: chemistry.

SUBSTANCE: fluoride nanoceramic is obtained by thermomechanical treatment of the starting crystalline material made from CaF2-YbF3, at plastic deformation temperature to obtain a workpiece in form of a polycrystalline microstructured substance, which is characterised by crystal grain size of 3-100 mcm and a nanostructure inside the grains, by annealing on air at temperature of not less than 0.5 of the melting point with compaction of the obtained workpiece in a vacuum at pressure of 1-3 tf/cm2 until the end of the deformation process, followed by annealing in an active medium of carbon tetrafluoride at pressure of 800-1200 mmHg. The starting crystalline material used can be a fine powder which has been subjected to heat treatment in carbon tetrafluoride, or a moulded workpiece of crystalline material made from the powder and heat treated in carbon tetrafluoride.

EFFECT: invention enables to obtain a fluoride nanoceramic with high degree of purity and high uniformity of the structure of said optical material.

4 cl, 3 ex

FIELD: process engineering.

SUBSTANCE: invention relates to processes used in operation at high pressure and modifying substances physically. Proposed method comprises placing diamond in reaction cell in pressure transmitting medium, increasing pressure in reaction chamber and it cooling. Note here that thermal treatment is carried out at temperature increase rate of 10-50°C/s and at 2000-2350°C by passing electric current via heater in cell from programmed power supply source with due allowance for temperature relaxation in said cell in heating. For this, note also that temperature relaxation constant is defined. Said cell is cooled after heating by switching off power supply in forming short diamond heating pulse in temperature range of over 2000°C with diamond total stay time smaller than 30 seconds. Allowance for temperature relaxation in said cell in heating for heating rate Vt and pre-definition of cell temperature relaxation constant τ is made by setting in said programmable power source the maximum temperature of heating to τVT above maximum treatment temperature of 2000-2350°C.

EFFECT: changing colour of low-grate natural diamond without notable graphitisation, high-quality gem diamonds.

2 cl, 5 dwg, 3 ex

FIELD: process engineering.

SUBSTANCE: invention relates to production of abrasive tools intended for machining metals and alloys. Proposed cycle of processing AT at TTB comprises heating AT at 2450 Hz in microwave chamber for near-100 mm-thick AT and at 890-915 Hz for over-100 mm-thick AT to complete polymerisation (hardening) and curing semis at said temperature with uniform forced removal of volatile matters released therefrom (hot vapor-gas mix) from thermostat free volume by airflow created by exhaust vent system of microwave chamber via slots made in thermostat front and rear walls to rule out saturation of said volatile matters. Temperature of processed semis is controlled by device incorporated with thermostat and airflow forced in thermostat is heated to temperature of semis.

EFFECT: higher quality.

1 cl

FIELD: process engineering.

SUBSTANCE: invention relates to diamond processing, in particular, by thermochemical process. Proposed method comprises applying layer of spirit glue composition onto diamond surface, said composition containing transition metal, for example, Fe, Ni or Co, and processing diamond thermally at temperature not exceeding 1000°C. To prepare spirit glue composition, powder of water-soluble salt of transition metal is used. Said powder in amount of 1-10 wt % of water solution is mixed with spirit solution of glue at salt water solution-to-glue spirit solution ratio of 1:1. Prepared mix is applied on diamond surface in 10-20 mcm-thick layer to be dried. Thermal processing of diamond is performed in two steps. Note here that, at first step, diamond is processed at 600-700°C for 1-2 min, while, at second step, it is processed at 800-1000°C for 15-30 min.

EFFECT: superhigh specific surface with nano-sized (100-200 nm) relief, expanded applications.

2 dwg, 7 ex

FIELD: physics.

SUBSTANCE: method involves thermomechanical processing of initial crystalline material made from metal halides at plastic deformation temperature, obtaining a polycrystalline microstructured substance characterised by crystal grain size of 3-100 mcm and intra-grain nanostructure, where thermomechanical processing of the initial crystalline material is carried out in vacuum of 10-4 mm Hg, thus achieving degree of deformation of the initial crystalline material by a value ranging from 150 to 1000%, which results in obtaining polycrystalline nanostructured material which is packed at pressure 1-3 tf/cm2 until achieving theoretical density, followed by annealing in an active medium of a fluorinating gas. The problem of obtaining material of high optical quality for a wide range of compounds: fluoride ceramic based on fluorides of alkali, alkali-earth and rare-earth elements, characterised by a nanostructure, is solved owing to optimum selection of process parameters for producing a nanoceramic, which involves thermal treatment of the product under conditions which enable to increase purity of the medium and, as a result, achieve high optical parameters for laser material.

EFFECT: nanosize structure of the ceramic and improved optical, laser and generation characteristics.

3 cl, 3 ex

FIELD: machine building.

SUBSTANCE: procedure for surface of diamond grains roughing consists in mixing diamond grains with metal powder and in heating obtained mixture to temperature of 800-1100°C in vacuum as high, as 10-2-10-4 mm. As metal powders there are taken powders of iron, nickel, cobalt, manganese, chromium, their alloys or mixtures. Powders not inter-reacting with diamond grains at heating can be added to the mixture.

EFFECT: fabrication of diamond grains with optimal amount of recesses, possessing specified geometric parametres; reduced losses of diamond material and maintaining strength characteristics of grains.

4 cl, 1 dwg

FIELD: physics.

SUBSTANCE: method involves subjecting a grown and hardened, i.e. correctly annealed crystal, to secondary annealing which is performed by putting the crystal into a graphite mould, the inner volume of which is larger than the crystal on diameter and height, and the space formed between the inner surface of the graphite mould and the surface of the crystal is filled with prepared crumbs of the same material as the crystal. The graphite mould is put into an annealing apparatus which is evacuated to pressure not higher than 5·10-6 mm Hg and CF4 gas is then fed into its working space until achieving pressure of 600-780 mm Hg. The annealing apparatus is then heated in phases while regulating temperature rise in the range from room temperature to 600°C, preferably at a rate of 10-20°C/h, from 600 to 900°C preferably at a rate of 5-15°C/h, in the range from 900 to 1200°C preferably at a rate of 15-30°C/h, and then raised at a rate of 30-40°C/h to maximum annealing temperature depending on the specific type of the metal fluoride crystal which is kept 50-300°C lower than the melting point of the material when growing a specific crystal, after which the crystal is kept for 15-30 hours while slowly cooling to 100°C via step-by-step regulation of temperature decrease, followed by inertial cooling to room temperature.

EFFECT: high quality of producing monocrystals of metal fluorides owing to increase in their homogeneity with maximum reduction of defects in grown crystals, which ensures high yield of the material with good optical characteristics, use of a special mode of preparation and carrying out secondary annealing primary grown and hardened crystals of metal fluorides enable to eliminate microinhomogeneities and small-angle off-orientations of crystals.

1 ex

FIELD: electricity.

SUBSTANCE: method includes the first stage of increasing temperature of single-crystal substrate ZnTe up to the first temperature of thermal treatment T1 and maintenance of substrate temperature within specified time; and the second stage of gradual reduction of substrate temperature from the first temperature of thermal treatment T1 down to the second temperature of thermal treatment T2, lower than T1 with specified speed, in which T1 is established in the range of 700°C≤T1≤1250°C, T2 - in the range of T2≤T1-50, and the first and second stages are carried out in atmosphere of Zn, at the pressure of at least 1 kPa or more, at least 20 cycles or at least 108 hours.

EFFECT: invention makes it possible efficiently to eliminate part of Te deposits without considerable deterioration of efficiency and improvement of light transmission of single-crystal substrate ZnTe.

5 cl, 3 dwg

FIELD: process engineering.

SUBSTANCE: invention relates to diamond grinding in making diamond rock cutting tool. Proposed method comprises processing the diamonds in velocity layer of magnetic fields together with ferromagnetic particles. Mix composed of ferromagnetic particles and diamond grains fills the cylindrical case by 0.25-0.35 of its volume. Diamond magnetic susceptibility is defined by the relationship: X1gR1(R1+R2)224μ0ρ2R22H2X2, where X1, X2 are diamond and ferromagnetic particle magnetic susceptibility, m3/kg; g is acceleration of gravity, m/s2; R1, R2 are diamond and ferromagnetic particle grain radii, m; µ0 is magnetic permeability of vacuum, (µ0=4π·107 GN/m); ρ2 is ferromagnetic particle density, kg/m3; H is magnetic field intensity, A/m. Note here that the relationship between diamond grain weight and that of ferromagnetic particles makes 0.51-0.61.

EFFECT: higher efficiency of grinding and quality of finished diamonds.

1 cl, 2 tbl, 1 ex

Up!