Method of obtaining fancy light-blue or fancy light greenish blue monocrystalline cvd-diamond and obtained product

FIELD: chemistry.

SUBSTANCE: invention relates to technology of producing coloured diamond materials, which can be applied as precious stones or cutting instruments. Method includes stages of growing monocrystalline diamond material in accordance with CVD-technology, with diamond material having concentration of single substituting nitrogen atoms [Ns0] less than 1 ppm; initial CVD-diamond material is colourless, or, in case it is not colourless, then, according to colour gradation brown or yellow, and if it is brown according to colour gradation, then it has level G (brown) of colour gradation or better for diamond stone with 0.5 carat weight with round diamond cut, and if it is yellow according to colour gradation, it has level T (yellow) of colour gradation or better for diamond stone with 0.5 carat weight with round diamond cut, and irradiation of initial CVD-diamond by electrons to introduce isolated vacancies into diamond material in such a way that product of the total concentration of vacancies × way length [Vt]×L, in irradiated diamond material at said stage or after additional processing after irradiation, including annealing irradiated diamond material at temperature at least 300°C and not higher than 600°C, constitutes at least 0.072 ppm cm and not more than 0.36 ppm cm.

EFFECT: diamond material becomes fancy light-blue or fancy light greenish blue in colour.

21 cl, 4 dwg, 3 tbl, 9 ex

 

The invention relates to a method for producing fancy pale blue or fancy pale blue-green diamond material in which carry out the irradiation of the diamond material, which was obtained by CVD technology (chemical vapor deposition). The invention also relates to a fancy pale blue or fancy pale blue-green CVD diamond material as such. In addition, the invention is a system that provides the possibility of obtaining the desired color of the diamond material within a color range from fancy blue to blue-green.

The term "fancy colored diamonds" is a classification concept established in the trading of precious stones, and is used to indicate unusually 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 and others in the edition of Gems &Gemology, vol 30, No. 4, 1994 (pp. 220-242).

Diamond materials, which exhibit a distinct color intensity, known in this area as "fancy" colored diamonds. Other diamond materials, which do not show such a distinct color, can be classified by grades scale American Gem the ideological Institute (GIA). According to this scale, diamond materials qualify letters of the alphabet from D to Z. the GIA Scale is well known. Grade D represents the highest level of gradation and the most colorless diamond material on the GIA scale, and Z represents the lowest level of gradation on the GIA scale, with diamond material of the variety Z appears to the naked eye light yellow. Diamond materials, higher grades (those on the GIA scale are closer to grade D) are generally considered more desirable than the diamond material of lower grade (those closer to the sort Z), both in the trading of precious stones, and industrial application forms. When the color of the diamond material is more intense than the Z, it becomes a "fancy" diamonds, whatever its color. However, when the diamond material see such an attractive color, such as blue, it is often described as a fancy colored diamond, even if the saturation may be a gradation of colour, which alphabet is earlier than Z. Using the gradation color according to the scale GIA, diamond sorters used set of standards color diamond stones, classified by D, E, F and so on up to Z, and qualify in color from colorless (for all gradations of color to F) through pale yellow to dark yellow (G to Z). Qualifying for the radzie color diamond material is compared with a set of color standards and then come the closest to him of the stone in the set of samples of color according to the color saturation. So, set the gradation of color by letter qualifying for diamond, for example, H or K. After was set alpha level of color gradations, for varieties of a number of G-Z color sorter will sort out the color tone for accompanying letter colors. This hue could, for example, be brown, yellow or blue. For example, the stone could be qualified as N (brown), if its color saturation, he was the closest to a rock N in the set of samples of color sorter colour stones from colorless to dark yellow and it has a noticeable brown color. In terms of color designations brown stones have a hue angle in the range from 0° to less than 90°, and yellow stones have a hue angle in the range of 90°-130°.

Famous blue diamonds of natural origin. Diamond material type IIb, which essentially does not contain nitrogen but contains boron absorbs red, orange and yellow light. Therefore, such a diamond material usually looks blue. The introduction to the description of patent document ERA (in the name of Sumitomo) includes a table that lists the original colors of a variety of natural rough diamonds, including natural blue diamonds of type IIb.

Also known formation fancy colored diamonds, including blue, processing ALM is the call which were not originally blue. For example, by John Walker in "Optical Absorption and Luminescence" ("Optical absorption and luminescence") in "Reports on Progress in Physics, volume 42, 1979, describes, among other things, that the irradiation of any diamond leads to a blue-green colour due to absorption bands in the red and violet regions of the spectrum absorption. As is, this so-called GR1 absorption band due to the neutral isolated vacancies V0in the structure of a diamond, each isolated vacancy is known as "GR1 center. The intensity GR1-band linearly dependent on the dose of irradiation, showing that the GR1 center is a genuine defect in the crystal lattice and is not related to any impurities in the diamond. Blue-green coloration of the diamond material, radiation, given in the author's publications Walker as an example.

Patent documents ARE and ARE describe irradiation of synthetic NRNT (obtained at high pressure/high temperature) diamond material electron beam or a neutron beam for the formation of lattice defects (defects of the implementation and vacancies in the crystal. After that, the diamond crystal is subjected to annealing in a preset temperature range for the formation of color centers. These papers shall then describe getting purple and red-pink diamond materials.

The first aspect of the present invention is a method of obtaining a fancy pale blue or fancy pale blue-green single-crystal CVD diamond material comprising the steps are:

i provide a single-crystal diamond material that has been grown using CVD technology, and the diamond material has a concentration [NS0] less than 1 ppm, and the original CVD diamond material is colorless, or if not colorless, color gradations, or brown, or yellow, and if it is brown in color gradations, has a level G (brown) color gradations for diamond stone weight of 0.5 carats (ct) with a round brilliant cut or better, and if it is yellow in color gradations, has T (yellow) color gradations for diamond stone weight of 0.5 carats (ct) with a round brilliant cut or better; and

(ii) conduct a radiation source CVD diamond material electron to introduce isolated vacancies in the diamond material so that the total work of the vacancy concentration × path length ([VT]×L) in the irradiated diamond material at this stage or after additional processing after irradiation is at least 0,072 ppm·cm and not more of 0.36 ppm·cm, resulting in a diamond material becomes fancy pale blue or fantasy is a diversified pale blue-green in color.

The term "NS0"has to do with single substitutional nitrogen atoms in the diamond material.

The perceived color of any particular diamond stone depends on the size and cut of the diamond. Therefore, where reference is made to the level of the gradation color diamond material in this area usually indicate this in terms of a standard size, usually 0.5 carats (ct), and the standard cut, usually round brilliant cut (often referred to 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 gradation of a standard size and cut. Therefore, the source of the diamond material used in the method according to the first aspect of the invention, can have any size or cut, but his color gradation, where she indicated, adjusted up gradation of color for this diamond material with a typical size of 0.5 CT and standard round brilliant cut.

Limits on the product of concentration of isolated vacancies × path length can be expressed as:

of 0.36 ppm·cm ≥[VT]×L≥0,072 ppm·see

Knowing that 1 ppm = 1,76×1017cm-3this can alternatively be written as:

2,04×10-18cm-2≥[VT]×L≥4.09 to×10-19cm-2.

The lengths of the paths for gemstone with round brilliant cut take 2 times greater than the depth of the stone. For example, the diamond material weight 0.5 CT round brilliant cut when the depth of the stone 0.3 cm and, therefore, the average path length is 0.6 cm limits would be:

0,6 ppm ≥[VT] ≥0,12 ppm.

CVD-diamond provided in step (i) of the method according to the first aspect of the invention, will be called in the present description "the source CVD diamond". The stage, which really grown CVD diamond material may be or may not be part of the method according to alternate embodiment of the invention. Getting CVD diamond material may mean, for example, simply selecting a pre-grown CVD diamond material.

Source CVD diamond material in the method according to the present invention has a concentration of [NS0] (which represents the concentration of defects, including single substitutional nitrogen) less than 1 ppm. The color of the original CVD diamond material may vary according to the concentration [NS0] and the terms of the mode in which it was grown diamond material. It is known that [NS0]-defects reported diamond material yellow staining, particularly at concentrations above 0.3 ppm in stones larger than 0,3 ct rbc (0,3 carat round brilliant cut).

It is also known that the presence of nitrogen with low concentrations in the environment CVD-cultivation which may affect the nature and concentration of other defects, entered in CVD synthetic diamond material as the growth of the diamond material, and that at least some of these other defects create color centers, causing the color of the CVD diamond material, usually giving the diamond material brown color.

It is also known that these color centers, which cause brown staining of CVD diamond grown in the presence of nitrogen in low concentrations, are unique to single-crystal CVD diamond, or fragments, carved, or fabricated from layers of single-crystal CVD diamond. In addition, it is known that the color centers, which cause brown staining of CVD diamond are different from those that create any brown staining observed in natural diamond, because defects in CVD diamond material are shown by absorption bands in the spectra of absorption in 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 (for example, with a wavelength of 785 nm or 1064 nm), which is not observed for brown natural diamond. In addition, it is known that these color centers in natural diamond material Prem who prevailed annealing at temperatures different from the temperature of the CVD diamond material.

It appears that some of the color centers, which cause brown staining, visible in CVD synthetic diamond grown by the ways in which the injected nitrogen in 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 in this regard. 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 levels of the different types of existing defects. A typical spectrum of the grown CVD synthetic diamond material grown in the presence of nitrogen added in the synthetic environment, shows a peak around 270 nm, which is due to the presence of neutral single substitutional nitrogen atoms (NS0in the crystal lattice of the diamond. Additional peaks were observed in the region of about 350 nm and about 510 nm, respectively other defects,characteristic and unique for CVD synthetic diamond material, and besides, there was a so-called "linear slope", which is an increase of the background level in the form s×λ-3where "C" is a constant and λ is the wavelength. While NS0can be identified mainly by its peak at 270 nm, it is also less involved in the absorption spectrum at higher values of wavelengths, in particular at wavelengths in the visible spectrum, which mainly consider covering the wavelength range from 350 nm to 750 nm.

There is a combination of signs, manifested in the absorption spectrum in the visible region of the CVD diamond material that is (a) the contribution of NS0in the part of the absorption spectrum in the visible region, (b) peak at 350 nm, (C) peak at 510 nm and (d) linear slope, which affect the perceived color of the diamond material and appear to be 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 NRNT-diamonds of the type described in the patent document ERA. For the purposes of the present description all defects other than NS0defects that appear in the absorption spectrum in view of what my portion of the spectrum, the authors of the present invention discussed above as characteristics of wavelength 350 nm, 510 nm and a linear slope, will be collectively referred to as "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 clusters of multiple vacancies (where each cluster is composed 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) process gas. Such clusters are thermally unstable and to some extent can be removed by high-temperature processing (i.e. annealing). It seems that smaller defects related to the job, such as defects in the form of complexes 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.

Depending on the method of preparation and concentration [N S0] source CVD diamond material used in the methods according to the invention may appear colorless, nearly colorless, pale yellow or pale brown. In accordance with the methods according to the present invention, the color of the original CVD-diamond qualifies either colorless or brown or yellow, and if brown, with a level of G (brown) color gradations or better, and if yellow, then have T (yellow) color gradations or better (for mass 0.5 CT round brilliant cut - RBC), scale American Gemological Institute (GIA). As noted above, on this scale diamond materials qualify with the designation of the letters of the alphabet from D to Z, with diamond material assign a level of gradation of color rather than the color intensity or saturation than the actual color tones for example yellow or brown) stones with known saturation, under controlled lighting conditions and strict surveillance. Grade D represents the highest level of gradation and the most colorless diamond material on the GIA scale, and Z represents the lowest level of gradation on the GIA scale, with diamond material of the variety Z appears to the naked eye pale yellow or brown. Diamond materials, higher grades (the hat, which on the GIA scale are closer to grade D) are generally considered more desirable than the diamond material of lower grade (those closer to the sort Z), both in the trading of precious stones, and in other embodiments of the application; therefore, when the authors of the present invention are saying "qualified as G or better," the authors of the present invention mean "qualified as G or letter, standing earlier in the alphabet than G". Diamond materials with a yellow or brown hue qualify letters on the same scale and with respect to the same set of standards color diamonds in each level of gradation in color. Therefore, the level of G (brown) color gradations means that there is some color and color component is brown. Diamond material, qualified as G (yellow), would have the same degree of color as a diamond material, qualified as G (brown), but the color components would be more yellow than brown. Typically brown diamond material has a hue angle <90°, and yellow diamond material has a hue angle between 90°-130°. Diamond material, qualified as F or better, has no visible color, and its only qualify letter or a letter followed by the symbol "colorless" in parentheses. If al is asny material has a color of yellow or brown hue, which is more intense than the level of the Z-gradation of color, he becomes a "fancy" colored diamond material. As noted above, the diamond material with a different detectable hue than yellow or brown in color, such as blue, which has a color that is intense enough to be registered, also known as "fancy". Therefore, the diamond material with a blue hue will be called "fantasy", when the intensity of the color is less than would be the case of yellow or brown colored diamond.

According to the present invention, the gradation level of G color or better is preferential to achieve fancy pale blue diamond material. On the other hand, the level of T gradations of color or better is primary for any original yellow diamond material, in this case resulting in fancy pale blue-green diamond material after irradiation. The degree of yellow tones in the original diamond material may be increased by increasing the concentration [NS0] provided that this can be done without increasing the number of other X-defects and associated brown staining. The authors of the present invention had the opportunity to grow CVD diamond with low and adjust the mi levels of nitrogen, at the same time minimizing the concentration of X-defects. For cultivation by CVD technology this is not normal. It provides not only the predominant presence of nitrogen in the CVD process is growing, which can be beneficial for reasons of morphology, but also for some variants allows you to enter a sufficient amount of nitrogen to give the diamond material yellow hue, which after irradiation according to the invention leads to a pale blue-green diamond material. The authors of the present invention had the opportunity to discover what it is possible to adjust the concentration of nitrogen in the CVD diamond within 20% of the target, at the same time maintaining a low concentration of defects, giving a brown color. This is mainly if you want to control the angle hue treated (irradiated) of the diamond material in the range of blue to blue-green.

Alternative or additional approach to the definition of the colors in the original CVD diamond material is to study its absorption spectrum recorded at room temperature. It is advantageous if the above-mentioned X-defects are minimized and make a minor contribution to the absorption spectrum of the source of the diamond material. Typically, where the concentration [NS 0] original diamond material is more than 0.1 ppm, but less than 1 ppm, preferably, the total integrated absorption in the visible region from 350 nm to 750 nm, which can be attributed to other defects than the NS0it was less than 90%, i.e. minimized X-defects, which cause brown staining. Where the concentration [NS0] are zero or very low, for example less than 0.1 ppm, the total integrated absorption in the visible region from 350 nm to 750 nm, which can be attributed to other defects than the NS0probably should be over 90%, even if the content causes brown staining X-defects very little, simply because of the concentration [NS0] themselves reduced to zero or very small. In these cases, it is preferential to the absorption coefficient (when the spectra are normalized to 0 cm-1at 800 nm) at 350 nm was less than 0.5 cm-1and at 510 nm was below 0.3 cm-1and these low absorption coefficients are a measure of the low level content causes brown staining X-defects in the diamond material. It should be noted that where the concentration [NS0] exceed 0.1 ppm, the absolute values of the absorption coefficients at 350 nm and 510 nm could be more, che is 0.5 cm -1and 0.3 cm-1accordingly, even when the concentration of [H-defects] are low, due to the contribution themselves NS0-defects in the absorption spectra in the region of 350 nm and 510 nm.

Another aspect of the present invention is a method of obtaining a fancy pale blue or fancy pale blue-green single-crystal CVD diamond material comprising the steps are:

i provide a single-crystal diamond material that has been grown using CVD technology, and the diamond material has a concentration [NS0] less than 1 ppm, and the total integrated absorption in the visible region from 350 nm to 750 nm, which can be attributed to defects other than NS0over 90%, and then the absorption coefficient at 350 nm is less than 0.5 cm-1and the absorbance at 510 nm is less than 0.3 cm-1and

(ii) conduct a radiation source CVD diamond material electron to introduce isolated vacancies in the diamond material so that the total work of the vacancy concentration × path length ([VT]×L) in the irradiated diamond material at this stage or after additional processing after irradiation is at least 0,072 ppm·cm and not more of 0.36 ppm·cm, resulting in a diamond material becomes fancy pale blue is m or fancy pale blue-green in color.

For all examples used in this description, the height of the absorption peaks and the values of the integral absorption used to calculate the percentage absorption of the original CVD diamond material, which can be attributed to defects other than NS0listed in this description, the measured spectrum UV/visible absorption of synthetic CVD diamond material recorded at room temperature.

All taken at room temperature absorption spectra, referred to here were recorded with a spectrometer Perkin Elmer Lambda-19. Recorded in the spectrum of the data (measured spectrum) were processed in the following way to obtain information on the proportion of the measured absorption in the range from 350 nm to 750 nm, which could be attributed to NS0and the proportion of the measured absorption, which can be attributed to other defects (X-defects).

A. 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.

b. Range return loss subtracted from the height data acquisitions, and from the obtained spectrum extracted absorption coefficient spectrum for the sample.

C. To determine the component of the measured spectrum, which can be attributed to NS0, absorption spectrum for NRT-synthetic diamond type Ib (for which the absorption is attributed to a only NS0) normalized, while from the measured spectrum is essentially not removed peak at 270 nm with subtraction from it. This normalization allows to determine the concentration of nitrogen.

d. Using the visible region of the spectrum as extended from 350 nm (i.e 3,2618 eV) to 750 nm (i.e 1,6527 eV) defined as the integral absorption in the visible region for the measured spectrum of the sample and the component therein, attributed to NS0and the percentage of integral absorption, which is attributed to the calculated defect NS0.

that is, In fact, return loss, in General, are higher than theoretical values, and this is, without employing the methods of calorimetry for specific wavelengths, makes it difficult to determine the absolute values of the absorption coefficient. To adjust for the additional losses that have indirect relation to the takeover, was used following the standard approach. Against lower energies, in General, was this situation that is below a given at the anti-shudder performance energy measured absorption no longer showed significant variations depending on the energy. The data of the absorption coefficient was transformed so that the absorption coefficient was applied to zero at 800 nm.

In accordance with other variants of the methods according to the present invention, the source CVD diamond may contain or may 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 spectroscopy optical absorption in the UV/visible region for higher concentrations.

Contents [NS0] neutral uncharged condition can be measured using electron paramagnetic resonance (EPR, ESR). Although this method is well known in the technology, it is summarized here for completeness. In the measurements performed using the EPR, the relative content specific paramagnetic defect (for example, a defect in the form of neutral single substitutional nitrogen atom) 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 stilnovo prevent saturation effects of microwave power or the introduction of amendments to them. Since the EPR spectra of stationary 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 cases where the obtained 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 model spectra of defects present in the sample, and determining the integrated intensity in each of the models. Experimentally observed that a good agreement with the experimental EPR spectra does neither Lorentz nor Gaussian line shape, therefore, for the model 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 use amplitude modulation, approximate or exceed the line width of the EPR signal, to achieve horsepasture "signal/noise" (which provides the ability to accurately determine the concentration within an acceptable temporal interval). 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). When 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 technology and includes measurement of the peak in the region of 270 nm the absorption spectrum of the diamond material.

Nitrogen may also be present in a positively charged state (N+), the concentration of N+find the measurement of the peak height of the absorption in the region 1332 cm-1in the FTIR spectrum (infrared spectrum with the Fourier transform). To obtain the total concentration of nitrogen in the diamond material can also be applied the method of SIMS (mass spectrometry of secondary ions), if the concentration is within the range of detection.

As noted above, the gradation level of G color or better is primary for any original brown diamond material, while the level of T gradations of color or better is acceptable for any original yellow diamond material. As also noted above, when a small amount of nitrogen present in the technologists who Eskom gas, and thus in the original diamond material, it is usually associated with the introduction of the so-called X-defects, which give the CVD diamond material brown staining. According to certain variants of the invention, when the CVD diamond material there are small amounts of nitrogen, treat special ways to get the source CVD diamond material in which any brown staining (estimated from these X-defects) avoid or at least reduce it to a minimum. Where is brown staining minimise this way, the concentration [NS0] can be up to 1 ppm, since any yellow staining in the presence themselves NS0-defects will lead to levels of NS0that give T (yellow) color gradations or better. In practice, for reasons of purity gas or characteristics of a diamond, or where it is desirable achievement rather more blue-green color tones than blue hue, can be pre-emptive maintenance of the concentration [NS0] closer to the upper limit of 1 ppm.

In particular, when the source CVD diamond material used in the method according to the present invention has a concentration [NS0] closer to the upper limit B1 ppm, absorption spectrum may have a total integrated absorption in the visible region from 350 nm to 750 nm, less than 90% of the integrated absorption can be attributed to other defects than the NS0then there are the so-called X-defects that appear responsible for the brown coloration, causing less than 90% of the integrated absorption in the visible region.

The present invention also provides the use of the original CVD diamond material, which lacks the NS0] or is present in very small quantities. In these cases, because there are very small numbers (NS0], thus in this way will be mainly very little X-defects or no will, therefore, low and missing brown staining (although under certain growth conditions, the situation may be different). It is possible to quantify, if you specify that the absolute coefficients in the absorption spectrum at 350 nm and 510 nm is less than 0.5 cm-1and 0.3 cm-1, respectively. So, if there is little or no [NS0], any coloring of the diamond material, probably due to rather any small amounts of brown than yellow, which attach themselves NS0), and in this case, the original CVD almann the second material has a level G (brown) color gradations or better. Such material can mainly have the following characteristics in its absorption spectrum (when the absorption at 800 nm normalized to 0 cm-1):

DesignationThe beginning of the peak (nm)The end of the peak (nm)Peak (nm)The absorption coefficient at the peak (cm-1)
270 nm Ns0220325270<0,8
The share of "X" for the band of 350 nm270450350±10<0,5
The share of "X" for strip 510 nm420640510±10<0,3

The method of growing CVD diamond material thoroughly developed and extensively described in the patent and other literature, for example in the patent document WO 03/052177. It appears that these previously published methods for growing CVD diamond material lead to the diamond material with an absorption spectrum, which is first characterized this total integrated absorption in the visible region from 350 nm to 750 nm, the contribution of other defects in the visible region of the spectrum would be more than 90%. Because these other defects, as is well known, lead to a characteristic brown colour CVD-diamond containing nitrogen, these are known from prototype methods CVD cultivation unfit for immediate cultivation source CVD diamond material used in the method according to the present invention.

One of the above special methods that can be performed to obtain baseline CVD diamond material, which avoid any brown staining (as expected, due to the aforementioned X-defects), consists in the application of the method is CVD-cultivation, in which process gas contains rather carbon, hydrogen, nitrogen and oxygen, rather than the more usual carbon, hydrogen and nitrogen. For example, oxygen may be added to the process gas in a concentration of at least 10000 ppm in the gas phase. In particular, the source CVD diamond material in step (i) of the method according to the first aspect of the invention may be grown directly in the manner described in the patent application in the UK GB0922449.4 and provisional application U.S. USSN 61/289282, full descriptions of which are incorporated herein by reference. More specifically, the method includes the steps to prepare the substrate; preparing a process gas and provide the opportunity for the awn homoepitaxial synthesis of diamond on the substrate; and environment synthesis includes the nitrogen atomic concentration from about 0.4 ppm to about 50 ppm; and process gas includes: 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; and Hf+Cf+Of=1; and the ratio of the atomic fraction of carbon atomic fraction of oxygen, Cf:Ofcorresponds to a ratio of about 0.45:1<Cf:Of< about 1.25:1"; and the process gas includes hydrogen atoms added as a hydrogen molecule, H2when the atomic fraction of the total numbers of atoms of hydrogen, oxygen, and carbon between the 0.05 and 0.4; and where the atomic fraction of HfCfand Ofrepresent a fraction of the total number of atoms of hydrogen, oxygen and carbon present in the process gas. This method of growing CVD diamond material will be named in the description as "CVD method of growing with the addition of oxygen".

Depending on the exact parameters used in the process (for example, the substrate temperature, the applied pressure and the amount of nitrogen in the process gas, the above-mentioned CVD method of growing with the addition of oxygen may be a direct result of the creation of the diamond material in which at least 90% interest the General absorption in the visible region from 350 nm to 750 nm can be attributed to defects, different from the NS0-defects (X-defects), or not. In General, CVD is a method of growing with the addition of oxygen allows a qualified employee to administer a higher percentage of nitrogen than would be possible in a standard CVD processes, at the same time with the reduction in the number of other defects, leading to the brown coloration. Thus, the present invention also provides for the use of the CVD method of growing with the addition of oxygen to the introduction of nitrogen in such high concentrations that the number of other defects is also significant and obtained the grown diamond material is more than 90% of the integrated absorption in the visible region from 350 nm to 750 nm, which can be attributed to X defects. This original diamond material could then be processed in the subsequent high-temperature annealing, as described below, to remove some or all of these defects. Exact adaptation CVD method of growing with the addition of oxygen in such a way as to obtain the desired concentration of defects in the diamond material and, therefore, absorption spectrum, will be the subject of simple experimentation for a qualified specialist in this field of technology.

CVD diamond material grown by CVD with the method of growing with the addition of oxygen, can be IP is alsoan directly as a source CVD diamond material in the method according to the invention. This path from stage CVD growth before the formation of the treated diamond material is illustrated as a "path A" in Fig.1 of the accompanying drawings.

Instead of directly use it as the source of the diamond material in the method according to the invention, CVD diamond material grown by CVD with the method of growing with the addition of oxygen, can be regarded as a precursor of the diamond material grown CVD method with the addition of oxygen, which is then subjected to high-temperature annealing at a temperature of at least 1600°C, or at least 1800°C, or at least 2000°C, to form the source CVD diamond material. CVD diamond material, prepared by CVD-method of growing with the addition of oxygen and then subjected to processing in the high-temperature annealing process, can generate source CVD diamond as used in the method according to the invention. The path to the source CVD diamond material is illustrated as the path In Fig. 1. It seems that this process of preliminary high-temperature annealing can further reduce any X-defects in the grown CVD diamond material and that it may be advantageous for certain variants. Stage of high-temperature annealing could be performed on svejeviratna or processed stone.

Another possibility consists in the cultivation of precursor CVD diamond material with the use of more commonly used CVD method, for example, of the type disclosed in the patent document WO 03/052177. In this way, as noted above, you can get diamond material with an absorption spectrum in which the total integrated absorption in the visible region from 350 nm to 750 nm is such that more than 90% of the integrated absorption could be attributed to unwanted X-defects, which cause brown staining. The authors of the present invention, this description will refer to this diamond material as "the precursor of the diamond material grown traditional CVD method", and the word "precursor" is used to show that the grown CVD diamond material is different from the original CVD diamond material, achieved by the method according to the present invention, and precedes it. The word "traditional" is used to distinguish the path of the precursor CVD-grown material, which is described above by Century Authors of the present invention have found that, if the precursor of the diamond material grown traditional CVD method, is subjected to processing in the above-mentioned high-temperature annealing process, this may cause the diamond material in which less than 90% of integrals the th absorption can be attributed to defects, different from the NS0-defects (X-defects that cause brown staining). The path to the source of the diamond material shown in Fig.1 as "path".

The present invention also provides the use as the source of the diamond material containing [NS0] in very low concentrations, for example less than 0.1 ppm. These materials can be grown using a method with a very low or zero concentrations of nitrogen in the process gas. The initial CVD diamond materials thereby not contain X-defects or contain the minimum number, since these X-defects are believed to originate from structural and charge changes in the diamond material deposited nitrogen in the structure of the diamond material; if the nitrogen is absent or present in a minimum quantity, these structural changes do not occur or occur to the minimum extent. Therefore, in certain variants of the method according to the invention using the original CVD diamond material having a concentration [NS0] below 0.1 ppm.

Ways of getting CVD diamond material containing very low or zero concentration [NS0], known in the art. For example, they are described in patent documents WO/O, WO/O, WO 2010/A and WO 2010/A, complete the contents of the descriptions of which are included in this description by reference.

For example, patent document WO/A describes CVD diamond material, particularly suitable for applications in electronic devices, where the levels of any single impurity is not more than 5 ppm, and the total content of impurities does not exceed 10 ppm. The level of any impurity content preferably does not exceed 0.5 to 1 ppm, and the total content of impurities is not more than from 2 to 5 ppm (where the term "admixture" does not include hydrogen and its isotopic forms). In the method described in patent document WO/A, the content of impurities in the medium, in which a CVD-cultivation, is regulated so that the growth proceeds in the presence of the atmosphere, essentially not containing nitrogen, that is less than 300 parts per billion (ppb), which has a molecular proportion of the total volume of gas, which is preferably less than 100 ppb, and the substrate on which the growth essentially contains no defects.

For example, patent document WO 2010/A describes a method of obtaining a diamond material with high chemical purity and high purity isotropic, suitable for use in the devices of spin electronics. In particular, the CVD method is growing includes the stages where we prepare a diamond substrate having a surface, which essentially does not contain lattice defects, and create, it is the policy of the gas mixture, including high-purity gases, where the nitrogen concentration is about 300 ppb or less, and a solid carbon source, including12With the amount of at least 99% of the total carbon content in the source, and activate and/or subjected to dissociation of at least a portion of the process gas and solid carbon source for the formation of gaseous carbon particles and allow homoepitaxial growth of diamond on the substrate surface.

Ways of getting CVD diamond material, for example, described in patent documents WO/O, WO/O, WO 2010/A and WO 2010/A, which essentially do not use nitrogen, will hereinafter be referred to as "method of growing high-purity CVD diamond material. These methods are suitable for forming the source CVD diamond material used in the methods according to the invention. Since high-purity source CVD diamond material formed in this way, essentially does not contain nitrogen and, therefore, has no X-defects, source CVD diamond material obtained by these high-purity ways, is a colorless, nearly colorless, or pale brown.

The color of the irradiated diamond material is a combination of the original color, if it occurs, the source of the diamond material and color, communicated what about the processing at the stage of irradiation, introduce isolated vacancies. Other impurities, which could give the original color of the diamond material, in certain variants can be minimized. For example, uncompensated boron (isolated boron) itself may inform the diamond material blue color. For some variants of the atomic concentration [B] of boron in the original 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 vacancies contact with boron so that neither boron nor compensating its isolated vacancies do not attach the diamond material of any color. Therefore, in some variants according to the present invention, if the diamond material contains uncompensated boron (for example, at a concentration of >5×1015cm-3), can be carried out stage irradiation to introduce isolated vacancies in a quantity sufficient not only to compensate the boron, but also to achieve a given concentration [VT] isolated vacancies. The level of additional exposure required to compensate the boron skilled in this technical field can be used to determine the experimental is here.

Adding more nitrogen to the original diamond material using methods that do not enter X-defects, which cause brown staining (for example, the aforementioned method with the addition of oxygen or removal of these defects (for example, during high temperature annealing) you can tell the source CVD diamond material greater degree of yellow color and thus after the stage of irradiation to obtain a blue-green diamond material. This seems to be provided by the fact that the presence of NS0in the material leads to charge transfer from V0for V-. For example, if there are relatively low concentrations of [NS0] the majority of vacancies present in the original diamond material is a neutral vacancy V0which tend to give a blue color. When there are relatively high concentrations [NS0] original diamond material is present in a greater number of negatively charged vacancies V-and they tend to message blue-green color. Thus, the invention is a convenient means for precise fit irradiated diamond material to all shades from pale blue to pale blue-green color simple modificirovannaya [N S0]. Proper regulation of the ratio V-/V0on the basis of different concentrations of nitrogen in the original diamond material, means that the hue angle can be varied to achieve the desired color (blue and green). Some embodiments of the invention include the choice of the concentration [NS0] original diamond material so as to create the target value V-/V0in the original diamond material. In addition to the color transition from blue to blue-green, due to different ratios of V-/V0also can manifest residual yellow color tone from any residual nitrogen, which would also be inclined to give a greener shade of blue-green diamond material after processing.

Another aspect of the present invention is a system that provides the ability to select and obtain the desired color of the diamond material within a color range from fancy blue to blue-green with a hue angle within the range of 100°-270°; and the system includes the steps are:

(a) pre-determine the target concentration [NS0] for growing CVD diamond material, which after irradiation this grown CVD diamond material will specify the WMD desired color;

(b) growing diamond material using CVD technology, which includes the steps, which introduce a sufficient amount of nitrogen in the process gas in the CVD process to achieve the specified target concentration [NS0] grown CVD diamond material, and CVD diamond material has the properties of the original diamond material, indicated at stage (i) of the method according to paragraph 1, of the formula; then

(C) carry out the step of irradiation described in stage (ii) method on the grown CVD diamond material.

Source 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 the CVD synthetic diamond material formed from a single sector growth. This single growth sector preferably is a {100} or {110}-sector growth. Material single sector growth preferably has a content of NS0within ±10% from an average value 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. Preference is given to the application source CVD diamond material is a, which was grown from a single sector growth as 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 nitrogen impurities, and therefore CVD synthetic diamond material, including many of the growth sectors, tend to be more undesirable areas with different color due to different concentrations of NS0in various growth sectors.

Where the methods according to the invention include the initial growth process of the original CVD diamond material, these methods preferably include the growing diamond material having the above percentages formed from a single sector growth.

Another advantage of using the original CVD-diamond mainly from a single sector growth is that in various growth sectors can be different numbers, distribution and types of defects.

Use rather CVD synthetic diamond material than natural diamond or NRT-synthetic diamond material, to obtain a pale blue diamond is preimushestvenno many reasons. For example, natural diamond has variable properties; therefore, it is difficult finding diamonds suitable for preparation kit decorative purposes. The advantage of the CVD diamond material before natural diamond material is that the process CVD synthesis and pokerstove processing can be precisely adjusted to achieve proper color tone and color saturation, comparatively with the need to choose from what is available. As another example, the diamond material produced using methods NRNT-synthesis, shows a very different absorption of nitrogen impurities on surfaces with different crystallographic orientations (which are the surfaces corresponding to different growth sectors), which are formed during the synthesis. NRNT approach usually does not ensure the formation of a single dominant sector growth in contrast to what is typically achieved in CVD technology. Therefore, the diamond material tend to be areas with different colors due to different impurity concentrations of nitrogen in different growth sectors. In addition, it is difficult to sufficiently control the synthesis process NRNT-diamond material to obtain a uniform and desirable concentration within even a single sects the RA growth within the synthesized diamond material. In addition, the synthesis NRNT-diamond material is typically detected impurities caused by the synthesis method and used catalysts - examples would include containing cobalt or Nickel, properties, which can lead to localized and uneven tension, which affects the optical and thermal properties. In contrast, CVD diamond material is much more uniform in color than natural and NRNT-synthetic diamond material, and will not create any problems with metal inclusions.

Synthetic CVD diamond material can clearly be distinguished from the synthetic diamond material synthesized NRNT-way, on the structure of dislocations. In the synthetic CVD diamond dislocations are mainly distributed in the direction that is approximately perpendicular to the initial growth surface of the substrate, that is, if the substrate is a (001)-substrate, dislocations are arranged approximately parallel to the [001]-direction. In synthetic diamond material synthesized using NRT-way, dislocations that are generated on the surface of the seed crystal (often on the surface, close to {001}), typically grow in the <110> directions. Thus, two types of material can be distinguished by their different is cnym observed structures of dislocations, for example, using x-ray topography. It also provides an approach to discernment CVD, natural diamond type IIa, as the natural diamond does not show such a clear parallel dislocations.

However, obtaining x-ray topographs is a difficult task, and, of course, would be a desirable alternative, less burdensome way, which would provide the ability to accurately distinguish.

Synthetic CVD diamond material can directly be distinguished from the synthetic diamond material synthesized NRNT-way, by the presence of metallic impurities in NRMT-synthesized material, which is embedded in the process of synthesis. Inclusions consist of metal, used as a metal-solvent and metal-catalyst, such as Fe, Co, Ni, etc. Inclusions can vary in size from less than 1 micron to over 100 microns. Larger inclusions can be observed using a stereomicroscope (e.g., Zeiss DV4); while smaller inclusions can be observed using transmitted light in metallurgical microscope (e.g., Zeiss Axiophot”).

An additional method that can be used to directly distinguish between synthetic diamonds obtained by CVD methods and NRT is photoluminescence spectroscopy (PL. If NRNT-synthesized material often contains defects that contain atoms from metal catalysts (typically transition metals) used in the synthesis process (for example, Ni, Co, Fe, and so on), and often the presence and detection of such defects using PL directly shows that the material was synthesized NRNT-way.

Stage (ii) of the methods according to the invention includes a stage on which to conduct the irradiation source diamond electrons. Stage irradiation is effective for the introduction of diamond isolated vacancies, as discussed earlier.

The authors of the present invention have found that the irradiated diamond material by radiation other than the flow of electrons, does not fancy pale blue or fancy pale blue-green colored diamond. In particular, the authors of the present invention found that the irradiation by neutrons gives a colored diamond yellow-green color.

As a rule, the higher the dose, the greater the number created isolated vacancies. The level of radiation dose and conditions of any processing after irradiation choose to work "[VT]×L" was at least 0,072 ppm·cm and not more of 0.36 ppm·see Typical stone weighing 0.5 CT round brilliant cut this corresponds to a concentration range [VT] of 0.12 to 0.6 ppm.

In some the x variants according to the invention the dose of electrons is chosen so that to enter in the irradiated diamond material "[VT]×L" level at least 0,072 ppm·cm and not more of 0.36 ppm·see In these cases it is preferable not to perform additional processing after exposure, which subjected the diamond material, which could significantly affect the concentration of isolated vacancies in the diamond material.

The diamond material may be subjected to irradiation so as to introduce isolated vacancies more than the final desired concentration. In these cases it is possible to further reduce the concentration of isolated vacancies on the stage of processing after exposure. The authors of the present invention have found that at this stage of processing after exposure can reduce the concentration of isolated vacancies up to about 50%. Stage of processing after exposure may include annealing the sample, for example, at a temperature of at least 300°C. or at a temperature not more than 600°C. the duration of the annealing may be short, for example, just a gradual rise in temperature from room temperature to the annealing temperature and then cooling the sample, or the sample can be maintained at the annealing temperature for a period of time of few or several hours, for example 2 hours. Without any limitation of the invention, the authors present invention polaha is t, the annealing at this temperature may cause any defect introduction, present in the material, become mobile and therefore diffuse and recombine with some of the isolated vacancies and, consequently, reduce the concentration of isolated vacancies. Such overexposure (for redundant isolated vacancies) with subsequent annealing to remove these redundant isolated vacancies adversely includes an additional step, but it can be used in certain circumstances and provided that the final concentration of isolated vacancies, obtained after further processing, is within predetermined limits, which fall within the scope of the present invention.

Therefore, other variants of the method according to the invention include an additional stage at which carry out the processing after irradiation the irradiated diamond material to achieve a value of "[VT]×L in the irradiated diamond material is at least 0,072 ppm·cm and not more of 0.36 ppm·see This stage of processing after irradiation may include a stage on which to perform annealing the irradiated diamond material at a temperature of at least 300°C. and not higher than 600°C. In these versions, because the annealing after irradiation can reduce the end is the acidity of isolated vacancies by almost 50%, the initial dose of electron irradiation can be selected to enter in the irradiated diamond material "[VT]×L is not higher than 0.72 ppm·see

An additional advantage of the irradiation of CVD diamond material is that the color of the material will generally be more resistant to low-temperature annealing and UV light compared with untreated CVD diamond. This stabilization effect is discussed in a patent application in the UK the number 0911075.0 and provisional application U.S. number 61/220663, both filed on June 26, 2009, and in the patent application in the UK the number 0917219.8 and provisional application U.S. number 61/24735, both filed October 1, 2009, a full description of which is included in this description by reference. Thus, an advantage of the present invention is that it leads to a blue or blue-green diamond material, which, in the absence of step exposure method according to the present invention, showed would be a measurable difference in at least one of its absorption characteristics in the first and second States, the first state occurs after exposure to radiation having energy of at least 5.5 eV, and the second state occurs after the heat treatment at a temperature of 798 K (525°C), but which, following the method according to the present invention, leads to the diamond is the material which exhibits little or no color change, as in the above first and second States, provided that the concentration of defects introduction was minimized. In some embodiments, execution change values* color saturation after irradiation between the first and second States is reduced at least by 0.5 compared to the diamond material which was not subjected to irradiation. In some versions change* after exposure of the diamond material in the first and second States is <1. In some versions of the irradiated diamond material or irradiated diamond material after additional processing after irradiation can have the absorption coefficient, measured at a temperature of 77 K (-196°C), at the level of at least 0.01 cm-1at a wavelength of 741 nm or absorption coefficient, measured at a temperature of 77 K (-196°C), at the level of at least 0.01 cm-1at a wavelength of 394 nm.

It is known that the radiation energy determines the penetration of radiation. As a rough approximation, each additional MeV energy electron beam will add an additional 0.7 mm penetration into the diamond. Typical sources available electron beam have an energy of 1.5 MeV and 4.5 MeV, and the authors of the present invention have found that predpochtitel the output is the source of electrons with an energy of 4.5 MeV irradiation, in order to achieve the desired penetration for diamonds with typical sizes; for example, for a diamond weight of 0.5 carats, having a thickness of about 3 mm, the Source of the electron beam can usually be 50% of the width of the scan and a current of 20 mA, for example, in the device used in the Isotron PLC.

The electron irradiation is typically carried out by the source beam in the energy range from 0.8 MeV to 12 MeV. Optional, used energy is such that introduces almost uniform concentration of isolated vacancies in the doped nitrogen in the diamond material, at the same time minimizing the formation of cascade damage, for example, chains of vacancies. For optimal results described here, it was found that the energy of 4.5 MeV provides a good compromise between these two factors.

Not necessarily, especially for larger samples, the rotation of the sample during irradiation or multiple turn followed by radiation can be used to contribute to the achievement of uniformity created isolated vacancies throughout the volume of the stone.

Concentration [VT] formed during the 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 exposed is the typical spend on the sample, established in the environment ~300 K (27°C), 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 so cold as possible (even with cryogenic cooling at 77 K (-196°C), which is predominant in some circumstances) to ensure the ability of high-dose radiation exposure without compromising temperature control and thereby to minimize the duration of exposure. It is the predominant production considerations. Calibration of the applied dose relative to vacancies created for specific source of diamond used to meet these limits input concentration [VTshall be within the competence of a qualified specialist prior to execution of the method according to the present invention. Methods such calibration are well-known practice for professionals, qualified in this field of technology.

The authors of the present invention have also found that the duration of exposure affects the number of isolated vacancies, which are introduced into the diamond material, and the rate of introduction of isolated Vaca is Ciego is different for different source materials and source temperatures.

A typical dose for diamond stone weight 0.5 CT round brilliant cut (rbc), when the sample has a temperature of ~350 K (77°C) is 1×1017- 1×1018e-cm-2.

Typical duration of exposure to the diamond stone weight 0.5 CT round brilliant cut (rbc), when the sample has a temperature of ~350 K (77°C) is 5-30 minutes, at an energy of 4.5 MeV, a current of 20 mA and 50% the width of the scanning using such a device, which acquired at Isotron PLC.

Throughout the present description to measure the concentration of isolated vacancies, the spectra obtained when the temperature of 77 K (-196°C) using liquid nitrogen to cool the sample, since at this temperature appear sharp peaks at 741 nm and 394 nm, which can be attributed to neutral and negatively charged isolated vacancies, respectively. The coefficients used for the calculation of the concentration of isolated vacancies in the present description, are as described by the author G. Davies in the publication Physica B, vol 273-274 (1999), pp. 15-23, as further shown below in table 1.

V-
Table 1
DefectCalibration
AND1=(4,8±0,2)×10-16[V-]
V0AGR1=(1,2±0,3)×10-16[V0]

In table 1, the symbol "A" represents the integral absorption (MeV·cm-1in the zero phonon line of the transition, measured at a temperature of 77 K (-196°C), with an absorption coefficient in cm-1and photon energy in MeV. Concentration specified in cm-3.

According to the methods according to the invention, the value of[VT]×L after irradiation or after additional processing after irradiation is at least 0,072 ppm·cm and not more of 0.36 ppm·see

Source CVD diamond material used in the method according to the present invention, and also irradiated CVD diamond material obtained by the method according to the present invention may be or may not be part of a larger fragment of the diamond material. For example, only a part of a larger fragment of the diamond material can be exposed and made blue, and/or only part of a larger fragment of the diamond material can be defined absorption features. As would be clear to a qualified specialist in this field of technology, many layers could also be subjected to irradiation and/or would have required the s absorption characteristics, so the original CVD diamond material used in the method according to the invention may form part, for example one or multiple layers, a larger fragment of the diamond material. It is well known that the penetration depth of the radiation depends on the energy of the radiation. Thus, in preferred variants the energy of the radiation is chosen so that the radiation penetrates only part of the depth of the CVD diamond material. This means that isolated vacancies could be entered only in the area CVD diamond material, where the radiation penetrates, and thus part of the CVD diamond material that has penetrated radiation, would be a "diamond material" used and generated in the method according to the present invention.

Where the original CVD diamond material is only part of a larger fragment of the diamond material, as discussed above, this source CVD diamond material as such can be used to override the optical properties described for certain embodiments of the invention. For example, the upper or subsurface layer or layers of the large fragment of CVD diamond material may have pale blue or pale blue-green staining. Where any other layers without pale blue or pale blue-green colors are essentially colorless, the color is this larger fragment of the diamond material is determined by the layer (s) with a pale blue or pale blue-green color.

In some variants according to the invention at least 50% or at least 60% or at least 70% or at least 80% or at least 90%, or essentially all the diamond stone can be mainly the same color.

In other variants according to the invention of the diamond stone may include layers or zones of the diamond material with the same color.

The advantage of the present invention is that, based on CVD diamond material with a specific concentration of nitrogen that is essentially colorless or pale-colored, and irradiation of CVD diamond material electron, it is possible to obtain a pale blue or pale blue-green diamond material. Accurate color between blue and green) you can change the regulation of the concentration of nitrogen. Mainly support at a low level, the content of any other components, for example other elements that could result in a different color. Exposure to regulate the introduction of diamond material isolated vacancies with specific concentration, thereby informing fancy pale blue or fancy pale blue-green color. These colored diamond materials may find particular application as precious stones, or colored filters, or as a cutting tool, such as rocks the PEL, and things like that. It should be noted that the term "colorless" and "white" are sometimes used as synonymous in the field to describe the color of diamond materials for precious stones.

The present invention also is diamond material, in any case obtained by the process according to the first aspect of the invention.

Fancy pale blue or pale blue-green CVD diamond material in which color is not determined solely, or entirely, boron, also is new. Therefore, the second aspect of the present invention is fancy pale blue or fancy pale blue-green CVD synthetic single crystal diamond material having a concentration of [B]<1×1015cm-3or [N]-[V]<1 ppm and the following color characteristics:

Table 2
DescriptionRange
The hue angle α100°-270°
optional 110°-230°
optional 120°-200°
The saturation C*At least 2 and not more than 10
optional 2-8
optional 2-6
The lightness L*>65
optional >70
optional >72

Color subjected to irradiation and annealing of diamond can quantify well-known by using a Chromaticity Coordinate CIE L*a*b*". The use of Chromaticity Coordinate CIE L*a*b* in the diamond described in the patent document WO 2004/022821, the full contents of the description of which is included in this description by reference. This method is particularly applicable for evaluation of color plates or blocks of diamond material. Color diamond with a round brilliant cut can be estimated either by eye trained person, or using the Chromaticity Coordinate CIE L*a*b* if the chamfer granina with the formation of flat back pad so that you get two parallel polished sides, through which conduct the measurement. 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* before the hat 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 following ratios between the wavelengths of 350 nm and 800 nm, with a step of measuring 1 nm:

Sλ= transmittance at a wavelength of λ,

Lλ= spectral power distribution of the illumination source

xλ= characteristic sensitivity of the eye to red,

yλ= characteristic sensitivity of the eye to green light,

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/Ysub> 0>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* corresponding to the 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 losses from agenie. Then the normalized absorption for an amendment to a different path length and 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 the color of the diamond material with an absorption data characteristics 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 with changes in length of the optical path for the diamond 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 absorption spectrum 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.

0-10weak
10-20weak the I-moderate
20-30moderate
30-40moderate-strong
40-50strong
50-60strong-very strong
60-70very strong
70-80+extremely strong

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

5-15extremely dark
15-25very dark
25-35dark
35-45mild/dark
45-55moderate
55-65light/moderate
65-75bright
75-85very bright
85-95Cressida is but light

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.

Will now be described, by way of example, embodiments of the invention, involving accompanying drawings, in which:

Fig.1, mentioned above, is a block diagram that shows the path in the methods according to the invention to obtain a pale blue or pale blue-green diamond material;

Fig.2 represents spectra, and absorption measured at room temperature, where a represents the range for the source of the diamond material used in examples 2-4 and 9, represents the spectrum of the starting material used in examples 1 and 8, and s is the spectrum of the starting material used in examples 5-7;

Fig.3 represents the spectra a, b and C absorption in the UV/visible region, measured at a temperature of 77 K (-196°C), where a, b and C represent, respectively, absorption spectra for examples 2, 3 and 4, each of which is shown after exposure, as specified; and

Fig.4 shows the spectra of a and b absorption, measured at a temperature of 77 K (-196°C), for the examples 2 and 6, accordingly, after irradiation, showing peaks ND1 and GR1, which are indicative of defects V0and V-respectively.

Examples

HPHT diamond-substrate available for synthesis of single-crystal CVD synthetic diamond material according to the invention, laser cut, laid on the substrate, polished to minimize subsurface defect so that the defect density was below 5×103/mm2and was generally below 102/mm2. Polished square HPHT-plate with dimensions of 3.6 mm × 3.6 mm, with a thickness of 500 μm, with all facial surfaces mainly on crystallographic planes {100}, with a surface roughness RQin this state, less than 1 nm, mounted on the refractory metal disk and placed in the reactor for growing CVD synthetic diamonds.

The growth stages

1) a Reactor for growing CVD diamond pre-prepared in particular by using 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 of thein situoxygen plasma using the flow of the gas mixture About2/Ar/N2in relation 50/40/3000 sccm (standard cubic centimeters per seconds is) and the temperature of the substrate 760°C.

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

4) This stage of processing continued the process of growing with the addition of a carbon source (in this case, CH4and alloying gases. In these examples, a process gas was present CH4flowing with the magnitude of the flow rate of 165 sccm, nitrogen with different levels for different examples 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 the2.

5)

ExampleDoping nitrogen in the process gas (ppm)A stream of oxygen (O2) present in the process gas (ppm)
1 and 81,80
2-4 and 90,090
5-71,013700

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

7) This CVD grown sample had a typical size of ~3,1×5×5 mm and a typical average path length of the light 6 mm

This grown CVD diamond is an "original diamond as defined in the claims of the present description.

Fig.2 represents spectra, and absorption, the spectrum And is responsible original diamond material used in examples 2-4 and 9, and is diamond material grown in high-purity CVD process is growing. In these examples, the percentage of the integrated absorption in the visible region of the spectrum of the original CVD diamond, which can be attributed to defects other than NS0is >90%. In these examples, this is because the absolute concentration [NS0] is low, as shown by the fact that there is no distinct peak in the region of 270 nm. The material has no brown staining, as the magnitude of the absorption at 510 and 350 nm are <0.5 and 0.3 cm-1, respectively. These high-purity materials are colorless and are CVD diamond material suitable for exposure in accordance with the method according to the invention. In Fig.2 range is In range of the source material used in examples 1 and 8. This source material is a CVD diamond material conventionally grown CVD-Viridian what I without oxygen in the process gas. In these examples, the percentage of the integrated absorption in the visible region of the spectrum of the original CVD diamond, which can be attributed to defects other than NS0is >90%, and, in addition, the magnitude of the absorption at 510 and 350 nm are >0.5 and 0.3 cm-1, respectively. Therefore, the original diamond materials of examples 1 and 8 are not raw source materials suitable for exposure method according to the present invention, and are pale brown color before irradiation. However, after being processed, for example, subjected NRNT-annealing before irradiation, as shown in example 8, they are the precursors of diamond materials suitable for exposure method according to the present invention. In Fig.2 spectrum is the spectrum of the starting material used in examples 5-7, which is a diamond material grown by the CVD method is growing with the addition of oxygen in the process gas. In this spectrum the magnitude of the absorption at 510 nm and 350 nm are >0.5 cm-1and 0.3 cm-1correspondingly, however, the percentage of the integrated absorption in the visible region of the spectrum of the original CVD diamond, which can be attributed to defects other than NS0is now <90%. These PR the measures represent the original material, suitable for irradiation in accordance with the method according to the present invention, and are pale yellow to radiation.

The electron irradiation all samples was performed by an electron beam with an energy of 4.5 MeV at 50% the width of the scan and the beam current of 20 mA. The irradiated diamond samples set in India on water-cooled copper block to prevent heating of the samples to temperatures above 350 K (77°C).

Table 3 illustrates the manner in CVD-growing (or the path to the source CVD diamond material, as shown in Fig.1, where applicable), the concentration of NS0in ppm, the proportion of total integrated absorption, which can be attributed to NS0-defects for samples of diamond materials obtained as described above, the absorption coefficient at 270 nm, 350 nm and 510 nm, the irradiation dose, the total concentration of vacancies (and the unit on the concentration of neutral and negatively charged isolated vacancies) and color before and after irradiation.

Table 3 includes a number of comparative examples. When considering, in turn, each of the examples in table 3, example 1 (which is a comparative example) shows traditionally grown CVD diamond material in which the percentage of integral absorption in the spectrum of the original diamond, which can the be attributed to defects, different from the NS0is of 91.6% and the absorption coefficients are 1,19 cm-1at 350 nm and 0.45 cm-1at 510 nm; its color before irradiation is pale brown, in other words, the source CVD diamond material beyond the criteria specified in step (i) of the method. After irradiation, the observed color of the diamond material is muted brownish-blue, but not desirable fancy pale blue or fancy pale blue-green according to the present invention. In addition, the color characteristics of example 1 are outside the limits specified in the main claim on the product of the present invention. Example 1 could be subjected NRNT-annealing, as shown in example 8 to make it suitable for pale blue/blue-green material, but being raw, it is unsuitable.

In example 2, 4, 5, and 7 (again comparative examples) use the original diamond that fall within the scope of phase 1 of the claim to the method of the present invention, but create works of art total concentration of isolated vacancies × path length, which is either below the required minimum level at least 0,072 ppm·cm (examples 2 and 5) or higher than the maximum (examples 4 and 7) 0.36 ppm·see the Color of these samples after the irradiation, it is desirable Fanta the applications of pale blue and fancy pale blue-green, and color characteristics beyond the values defined in the main claims on the product.

Fig.3 shows the spectra of a, b and C in the UV/visible region, taken at a temperature of 77 K (-196°C) after irradiation, where the spectrum is the spectrum of example 2 and shows a peak height GR1) the concentration of isolated vacancies, which is too low to impart desirable fancy pale blue/blue-green color desired for the present invention; range is In range of example 3, and shows the concentration of isolated vacancies, which is within the scope of the claims of the patent, and will inform desirable fancy pale blue/blue-green color, desirable for the present invention, and the range is the range of example 4 and shows the concentration of isolated vacancies, which is too high to give the desired fancy pale blue/blue-green color desired for the present invention. Another indicator of the concentration of isolated vacancies after irradiation of these samples are shown in table 3, which includes a column showing the concentration of V0and V-after exposure in ppm, and these data were calculated by integrating the area under the peaks of the GR1 and ND1, respectively.

In example 9 (again comparative is m example) using irradiation rather neutrons, than electron radiation. This leads to bright yellow diamond material after irradiation, with values S* and L* are outside the limitations of the formulas of the present invention.

Comparison of examples also shows how you can modify the angle of the hue (and thus accurate colors) within the stated range by changing the concentration of NS0in the original diamond. Both examples 3 and 6 give a pale blue/pale blue-green coloration, but the exact hue angle was modified by the introduction of various concentrations of NS0.

Fig.4, which represents the absorption spectra recorded after irradiation of examples 3 and 6, shows the different proportions of defects V0and V-formed respectively to the same radiation source for materials containing different concentrations of NS0. The spectrum of a, which represents the spectrum of example 3, which contains a low concentration [NS0] almost does not show any peak ND1 at 394 nm (showing that the sample contains almost no defects V-). On the contrary, the spectrum, which represents the range of example 6, which contains a higher concentration [NS0] shows increased height ND1-peak at 394 nm (showing high concentrations of defects V-). the BA range a and b show comparable peaks GR1 and thus the ratio GR1-peak:ND1-peak", which shows that the ratio of defects "V0:V-is higher for the spectrum of a (example 3) than for the spectrum In (example 6).

1. Fancy pale blue or fancy pale blue-green CVD synthetic single crystal diamond material having a boron concentration [B] <5×1015atoms/cm3and the following color characteristics:

2. Fancy pale blue or fancy pale blue-green CVD synthetic single crystal diamond material under item 1, with the product of the total concentration of isolated vacancies × path length, [Vt]×L, at least 0,072 ppm·cm and not more of 0.36 ppm·see

3. Fancy pale blue or fancy pale blue-green CVD synthetic single crystal diamond material under item 1 or 2, with (i) the absorption coefficient, measured at a temperature of 77 K of at least 0.01 cm-1at a wavelength of 741 nm and (ii) the absorption coefficient, measured at a temperature of 77 K of at least 0.01 cm-1at a wavelength of 394 nm.

4. A method of obtaining a fancy pale blue or fancy pale blue-the green circle single-crystal CVD diamond material p. 1, the method includes the steps are:
i provide a single-crystal diamond material that has been grown using CVD technology, and the diamond material has a concentration of single substitutional nitrogen atoms [Ns0] less than 1 ppm, the original CVD diamond material is colorless, or if not colorless, color gradations of brown or yellow, and if it is brown in color gradations, has a level G (brown) color gradations or better for the diamond stone weight of 0.5 carats (ct) with a round brilliant cut, and if it is yellow in color gradations, has the level of T (yellow) color gradations or better for the diamond stone weight of 0.5 carats (ct) with a round brilliant cut; and
(ii) conduct a radiation source CVD diamond material electron to introduce isolated vacancies in the diamond material so that the total work of the vacancy concentration × path length, [Vt]×L, in the irradiated diamond material at this stage or after additional treatment after exposure, including annealing the irradiated diamond material at a temperature of at least 300°C. and not more than 600°C, is at least 0,072 ppm·cm and not more of 0.36 ppm·cm, resulting in a diamond material becomes fancy pale blue or fancy pale blue-green in color.

5. The method pop. 4, in which the source of the diamond material is a brown or yellow color gradations, and if it is brown in color gradations, has a hue angle in the range from 0° to less than 90° to the diamond stone weight of 0.5 carats (ct) with a round brilliant cut, and if it is yellow in color gradations, has a hue angle in the range of 90°-130° for diamond stone weight of 0.5 carats (ct) with a round brilliant cut.

6. The method according to p. 4, in which there is no additional processing after exposure, and the dose of electrons is chosen so as to create in the irradiated diamond material is the product of the total concentration of isolated vacancies × path length, [Vt]×L, at least 0,072 ppm·cm and not more of 0.36 ppm·see

7. The method according to p. 4, including an additional step, which carry out the processing after irradiation the irradiated diamond material to achieve works total concentration of isolated vacancies × path length, [Vt]×L, at least 0,072 ppm·cm and not more of 0.36 ppm·see

8. The method according to p. 7, in which the dose of electrons is chosen so as to create in the irradiated diamond material is the product of the total concentration of isolated vacancies × path length, [Vt]×L, not more than 0.72 ppm·cm in front of the stage of processing after exposure.

9. The method according to p. 4, in which, with respect to the source of the diamond material, if the total integrated absorption in the visible region from 350 nm to 750 nm, which can be attributed to defects other than Ns0over 90%, the absorption coefficient at 350 nm is less than 0.5 cm-1and the absorbance at 510 nm is less than 0.3 cm-1.

10. The method according to p. 4, including the stage at which they grow is a precursor of the diamond material to be used directly or after further processing as the source of the diamond material, and the precursor of the diamond material has such an absorption spectrum with a total integrated absorption in the visible region from 350 nm to 750 nm, which is not more than 90% of the integrated absorption can be attributed to defects other than [Ns0].

11. The method according to p. 10, in which the CVD method includes a stage on which the process gas type oxygen with a concentration of >10000 ppm of oxygen molecules in the gas phase.

12. The method according to p. 10, in which the phase in which the grown diamond precursor material includes the steps to prepare the substrate and process gas and provide an opportunity homoepitaxial synthesis of diamond on the substrate, and environment synthesis includes the nitrogen atomic concentration from about 0.4 ppm to about 50 ppm and process gas includes: a) an atomic fraction 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) and the Ohm fraction of oxygen, Offrom about 0.13 to about 0.4; and Hf+Cf+Of=1 and the ratio of the atomic fraction of carbon atomic fraction of oxygen, Cf:Ofcorresponds to a ratio of about 0.45:1<Cf:Of< about 1.25:1; and the process gas includes hydrogen atoms added as a hydrogen molecule, H2when the atomic fraction of the total numbers of atoms of hydrogen, oxygen and carbon from 0.05 to 0.4 and atomic fraction of HfCfand Ofrepresent a fraction of the total number of atoms of hydrogen, oxygen and carbon present in the process gas.

13. The method according to p. 4, in which the target concentration [Ns0] pre-set according to the desired final color of the irradiated diamond material and the actual concentration [Ns0] in the original CVD diamond material regulate within 20% of the specified target concentration [Ns0].

14. The method according to p. 4, including steps, which are the precursor of the diamond material and then carry out the annealing of the grown CVD diamond material at a temperature of at least 1600°C. to obtain the CVD diamond material provided in step (i).

15. The method according to p. 4, in which the source CVD diamond material in step (i) has a boron concentration [In] less than 5×1015atoms/cm3.

16. The method according to p. 4, to the torus uncompensated boron is present in the original diamond material at a concentration of > 5×1015cm-3and on the stage of radiation is introduced into the diamond material, a sufficient number of isolated vacancies, so that excess product of the concentration of isolated vacancies × path length, after isolated vacancies were used for compensation of boron after irradiation or after additional processing after irradiation, there were at least 0,072 ppm·cm and not more of 0.36 ppm·see

17. The method according to p. 4, in which the dose is 1×1017-1×1018e-cm-2for diamond stone weight 0.5 CT round brilliant cut.

18. The method according to p. 4, in which the original diamond material has a measurable difference in at least one of its absorption characteristics in the first and second States, the first state occurs after exposure to radiation having energy of at least 5.5 eV, and the second state occurs after the heat treatment at a temperature of 798 To and after irradiation change values* color saturation between the diamond material in the first and second States is reduced by at least 0.5.

19. The method according to p. 4, in which after irradiation change* the diamond material in the first and second States is less than 1, and the first state occurs after exposure to radiation having energy in ENISA least 5.5 eV, and the second state occurs after the heat treatment at a temperature of 798 K.

20. The method according to p. 4, including the stage at which you choose concentration [Ns0] original diamond material to create a target ratio of negatively charged vacancies to the neutral vacancies V-/V0in the original diamond material.

21. The selection method and obtain the desired color of the diamond material within a color range from fancy blue to blue-green with a hue angle in the range 100-270°; and the method includes the steps are:
(a) pre-determine the target concentration [Ns0] for growing CVD diamond material, which after irradiation this grown CVD diamond material will lead to the specified desired color;
(b) growing diamond material using CVD technology, which includes the steps, which introduce a sufficient amount of nitrogen in the process gas in the CVD process to achieve the specified target concentration [Ns0] grown CVD diamond material, and CVD diamond material has the properties of the original diamond material, indicated at stage (i) of the method according to p. 4; and
(C) conduct the phase of the radiation that is specified in step (ii) of the method according to p. 4, grown CVD diamond material.



 

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2 cl, 5 dwg, 3 ex

FIELD: chemistry.

SUBSTANCE: invention can be used in obtaining jewellery diamonds. method of introduction of NV-centres in monocrystalline CVD-diamond material includes the following stages: irradiation of CVD-diamond material, containing single substituting nitrogen, for introduction of isolated vacancies in concentration at least 0.05 ppm and at most 1 ppm; annealing irradiated diamond to form NV-centres from at least some of defects of single substituting nitrogen and introduced isolated vacancies.

EFFECT: invention makes it possible to obtain pink CVD-diamond material and CVD-diamond material with spintronic properties.

18 cl, 12 tbl, 7 dwg

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