JPH09175807A - Preparation of diamond single crystal by recrystallization - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a uniform diamond single crystal as a whole. SOLUTION: This method for producing a diamond single crystal by a recrystallization is to perform a dissolution treatment and recrystallization treatment to a lump of a raw material diamond. The raw material diamond has the single crystal portion at least in a part, and in the dissolution treatment the lump of the raw material diamond is dissolved by leaving at least one part of the single crystal portion as a seed crystal. In the recrystallization treatment, the diamond single crystal 6 is precipitated by utilizing a remaining seed crystal 5 as a nucleus from a solvent dissolving the carbon component of the lump of the raw material diamond, and a homogeneous recrystallized diamond 7 is obtained.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a diamond single crystal by utilizing a temperature difference growth method.

[0002]

2. Description of the Related Art Conventionally, in a method for producing a diamond single crystal, research and development have been carried out mainly with the question of how to grow a carbon raw material into a large crystal. As a method for producing diamond, under stable high temperature and high pressure conditions, iron group elements and their alloys are used as a solvent, and carbon dissolved in the solvent is brought into contact with a seed crystal of diamond placed at a low temperature portion to form a seed crystal. There is a method for growing a single crystal centered on the above, and this method is generally well known in the field of diamond manufacturing technology as a temperature difference growth method.

In the temperature difference growth method, a solvent is sandwiched between a seed crystal and a carbon raw material in the upper portion to make the temperature conditions of the carbon raw material and the seed crystal different from each other.
This is a method for producing diamond by setting the heating temperature of the carbon raw material and the seed crystal so that the temperature becomes 0 ° C. high. According to the temperature difference growth method, since the solubility of carbon from the high temperature carbon raw material to the solvent is higher than the solubility of carbon from the seed crystal to the solvent, the dissolution of carbon from the carbon raw material to the solvent proceeds, The raw material carbon dissolved in the solvent is transported to the seed crystal side, a new crystal grows with the seed crystal as a nucleus, and a large crystal can be grown.

In order to grow a diamond single crystal using the temperature difference growth method, it is necessary to control various factors in addition to controlling the temperatures of the carbon raw material and the seed crystal. In particular, the seed crystal is protected. It is important to. If the seed crystal is completely dissolved in the solvent before the crystal growth with the seed crystal as the nucleus or before the raw material carbon is saturated in the solvent, the starting point that becomes the nucleus for the crystal growth is lost. As a result, the crystal cannot be grown from the seed crystal.

As a method for solving this problem, there is a technique in which the seed crystal and the solvent are isolated by a blocking layer until the solvent is saturated with carbon of the raw material carbon to suppress the dissolution of the seed crystal.

Japanese Patent Publication No. 59-6808 discloses that the growth of gem-grade diamond can be achieved by blocking the action of the catalyst / solvent substance on and near the seed crystal surface until a substantial diamond growth pattern is developed. It is described to insert a nucleation-suppressing or sequestering barrier layer or both between the catalyst / solvent mass and the seed crystal, as it prevents interfering spontaneous nucleation and seed crystal erosion to be minimized. ing.

In this prior art, the barrier layer for suppressing nucleation is preferably cobalt, iron, manganese, titanium, chromium, tungsten, vanadium, niobium, tantalum, zirconium, alloys of these metals, natural mica, polycrystalline. High density alumina, powdered alumina, quartz, quartz glass, hexagonal boron nitride crystal, cubic boron nitride crystal,
It is composed of a wurtzite-type boron nitride crystal, silicon carbide protected by a member of the platinum group metal, and the like.

The isolation barrier layer is preferably platinum, molybdenum, titanium, tantalum, tungsten, iridium,
It is composed of osmium, rhodium, palladium, vanadium, ruthenium, chromium, hafnium, rhenium, niobium, zirconium, and alloys of the above metals. If a nucleation inhibiting barrier is also used, the isolating barrier preferably comprises a different material than the nucleation inhibiting barrier. Is explained. In this prior example, since the diamond single crystal is grown in the solvent layer, nuclei are likely to occur at the bottom of the solvent, which causes growth on the seed crystal to be hindered, and from many nuclei. Since the crystals grow, the grown crystals interfere with each other and a crystal having an irregular shape is easily obtained. The nucleation suppression blocking layer is selected so that growth does not occur at a position other than the seed crystal, and this prior art discloses a suitable material for achieving the above object.

[0009]

However, a material that melts at a temperature higher than that of the solvent mass is selected for the barrier layer, but a part of the material melts at a high temperature during the treatment to form a grown diamond. It seems to have an impact. Also, in this prior example, a wire is embedded in the barrier layer,
An example is described in which this is melted and a carbon-rich molten catalyst / solvent metal is circulated in the diamond pocket to grow diamond, but since the substance forming the barrier layer is mutually soluble with the solvent metal, It is practically difficult to obtain a suitable seed crystal in which the wire portion made of a metal component becomes a growth portion accurately and the barrier layer is not penetrated.

According to experiments actually conducted by the inventor, when a diamond single crystal is grown by using the temperature difference growth method, inclusions (inclusions) are often generated near the seed crystal, and It was found that defects such as unfilled crystals occur. The cause is not necessarily clear, but it is thought that although the use of the blocking layer can prevent the dissolution of the seed crystal, it roughens the surface of the seed crystal and the initial crystal growth does not occur uniformly. .

An object of the present invention is to provide a method for producing a diamond single crystal in which the raw material diamond ingot is melted and recrystallized to sufficiently control the impurity concentration and the defect concentration.

[0012]

To achieve the above object, in the method for producing a diamond single crystal by recrystallization according to the present invention, a diamond single crystal by recrystallization having a dissolution treatment and a recrystallization treatment is used. In the manufacturing method, the raw diamond ingot has a single crystal diamond portion in at least a part, and the dissolution treatment dissolves the carbon component of the raw diamond in a solvent while leaving the single crystal diamond in at least a part. The recrystallization treatment is a treatment for growing a diamond single crystal by precipitating a carbon component in a solvent with the single crystal diamond of the raw material diamond lump left by the dissolution treatment as a seed crystal.

The raw diamond ingot is a single crystal diamond, and the recrystallization treatment is performed in a state where a part of the single crystal diamond in the raw diamond ingot is not melted.

The raw diamond ingot is a single crystal diamond layered with a carbon raw material. The carbon raw material is a combination of at least one of powdered diamond, diamond sintered body, graphite and non-diamond carbon. It is laminated on a single crystal diamond, and the recrystallization treatment is performed in a state in which all of the carbon raw material is dissolved and at least a part of the single crystal diamond is undissolved.

At least one of the single crystal diamond, powdered diamond, sintered diamond, graphite, and non-diamond carbon contains a specific mass number component of carbon in high purity.

The melting treatment is carried out by embedding the raw diamond ingot in a neutral substance and keeping a part of the raw diamond ingot in contact with the solvent. The neutral substance is a diamond single crystal growth. It is a solid substance that does not react with either solvent or carbon under the conditions.

The melting treatment is carried out by holding the melting temperature in the melting and recrystallization temperature region, which is determined by the solvent composition, the composition and morphology of the raw diamond ingot, and the melting conditions, for a certain period of time. Is carried out by maintaining the temperature lower than the melting treatment temperature within the above temperature range.

Further, the melting treatment and the recrystallization treatment are performed by exposing the raw diamond mass to a melting temperature in the melting and recrystallization temperature region which is determined by the solvent composition, the composition and morphology of the raw diamond mass, and the melting conditions. It partially dissolves it, and then spontaneously advances the growth of the diamond single crystal.

The recrystallization treatment is a treatment for forming a diamond single crystal having substantially the same size and morphology as the raw material diamond ingot before the melting treatment, and the recrystallized diamond single crystal has a defect. It is a diamond single crystal whose concentration and impurity concentration are different from those of the raw diamond ingot.

The recrystallization treatment is a treatment for growing a diamond single crystal in a neutral substance after the raw material diamond mass is melted.

The recrystallization treatment is a treatment for taking in the carbon component of the raw diamond ingot dissolved in the solvent together with the carbon component replenished in the solvent and converting them into a diamond single crystal.

In the present invention, as the raw material diamond ingot, it is possible to use one in which all the raw material diamond ingot is a single crystal diamond, or one in which a single crystal diamond and a carbon raw material are laminated. Carbon raw material is powder diamond,
Besides diamond sintered bodies, graphite and non-diamond carbon can be used. The powdered diamond, graphite, or non-diamond carbon may be powder or solidified in advance into a compact. One kind or two or more kinds of carbon raw materials are selected and laminated on the single crystal diamond. When two or more kinds of carbon raw materials are selected and used, they may be layered or mixed as a powder. In order to obtain an integrated diamond in the recrystallization process, all the carbon raw materials laminated in the melting process must be completely melted. The seed crystal of the raw diamond ingot and the diamond grown by the recrystallization treatment are single crystal diamonds. In the present invention, the former is referred to as a single crystal diamond and the latter is referred to as a diamond single crystal to distinguish the two in terms of expression.

Since the recrystallization treatment temperature proceeds at a temperature slightly lower than the melting treatment temperature, the recrystallization treatment naturally proceeds due to the temperature distribution peculiar to the apparatus for growing a diamond single crystal at ultrahigh pressure. To do. Therefore, in reality, recrystallization proceeds substantially if the melting temperature is maintained for a certain period of time. For the purpose of adjusting the recrystallization treatment rate, it is also possible to supply carbon to the solvent from another portion as in the temperature difference growth method.

As the solvent, any known solvent which dissolves carbon and precipitates as diamond can be selected. Representative solvents include those containing Fe, Co, Ni and their alloys as main components.

The neutral substance for embedding the raw diamond ingot is a solid substance that does not react with any of the solvent and carbon under the diamond growing conditions, such as salt, calcium fluoride, magnesium oxide, alumina, magnesia and other solvents. Ceramic materials that do not react can be selected.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION The inventors of the present invention have embeded a single crystal diamond in a neutral substance, and did not place a blocking layer at the boundary between the solvent and the surface of the single crystal diamond partially exposed from the neutral substance. Stable pressure conditions, eg 6G
The following findings were obtained by conducting experiments at various temperatures in Pa. (1) The single crystal diamond melts under the temperature and pressure conditions capable of growing the diamond single crystal, but the extent thereof varies depending on the temperature. (2) At low temperature, the single crystal diamond is less melted, but the surface of the grown diamond single crystal becomes rough. (3) At high temperature, melting of the single crystal diamond occurs quickly, and the single crystal diamond disappears. Some diamonds may grow irregularly from elsewhere than the single crystal diamond. (4) There is a temperature region where the single crystal diamond is partially melted in the intermediate region between the temperature regions of (2) and (3), and the surface of the unmelted portion is very smooth. In the present invention, this region is called a melting and recrystallization temperature region.

(5) When the single crystal diamond is melted only in the above part, a new diamond single crystal grows so as to fill the melted part again with the remaining single crystal diamond as the nucleus. The recrystallization temperature at which this new diamond grows is actually lower than the melting temperature described in (4), but the growth occurs more rapidly, but since the melting temperature and the recrystallization temperature are very close to each other, The growth by recrystallization proceeds even if the temperature is not substantially lowered. Therefore, if the temperature is set within the range of the melting and recrystallization temperature region, the melting of the raw material diamond ingot and the subsequent recrystallization of the diamond single crystal proceed by themselves. (6) The orientation of the newly grown diamond single crystal is completely the same as that of the single crystal diamond. That is, a new diamond single crystal having an epitaxial relationship with the single crystal diamond grows. (7) The total amount of the single crystal diamond and the newly grown diamond single crystal is almost the same as the original single crystal diamond, and the shape is also the same. (8) The single crystal diamond and the diamond single crystal described above correspond to the situation where the diamond originally buried in the neutral substance is recrystallized.

Based on the above findings, the present invention is to recrystallize diamond under the following conditions.

In the present invention, a material corresponding to the seed crystal used in the temperature difference growth method is called a raw diamond ingot. A part of the raw diamond ingot needs to be left after the melting, and the remaining part must be a single crystal. The part to be melted may be single crystal diamond, but powder diamond, diamond sintered body, graphite, and other non-diamond carbon are used as carbon raw materials as long as the total amount is melted by the melting process even if it is not necessarily single crystal diamond. it can. In addition, powder diamond, diamond sinter, graphite, and other non-diamond carbon to be laminated and melted as a carbon raw material on all parts including single crystal diamond parts of these various raw diamond masses or single crystal diamond are specified. When the mass number component of carbon is contained in a high purity, the recrystallization treatment provides a diamond single crystal having a high mass number in purity.

FIG. 1 shows an arrangement example of the sample in the cell 1. In FIG. 1, most of the raw diamond ingot 2 is embedded in the neutral substance 3, and a part of the raw diamond ingot 2 is exposed from the neutral substance 3 so as to be in direct contact with the solvent 4.

In the present invention, when the diamond is not squeezed out into the solvent 4 to grow the diamond, even if the amount of the solvent 4 is small, there is no problem in the growth of recrystallization. It is not necessary to dispose the raw material carbon layer on the solvent 4, but it does not matter if the raw material carbon layer is disposed on the solvent. When the raw material carbon layer is placed on the solvent, recrystallization is promoted, and the carbon component replenished in the solvent is taken in and converted into a diamond single crystal, and further reaches the solvent layer on the neutral substance to reach the diamond layer. It is also possible to grow single crystals.

If the amount of the solvent 4 is reduced in the limited space, the size of the raw diamond ingot 2 becomes relatively large. The cell 1 is installed in the furnace, and the sample is held for a certain period of time at the melting temperature located at a relatively high temperature in the melting and recrystallization temperature region.

By the dissolution treatment, at least a part of the single crystal diamond is left as the seed crystal 5, and most of the raw material diamond mass 2 is melted. Raw diamond lump 2
The carbon generated by the dissolution of is dissolved in the solvent 4. The solvent liquid phase containing carbon is shown in FIG. This solvent fills the cavities formed in the neutral substance 3 by the dissolution of the raw diamond ingot 2 and basically becomes a liquid phase in the shape of the raw diamond ingot 2.

In the recrystallization treatment following the dissolution treatment, the carbon component of the raw material diamond ingot 2 dissolved in the solvent with the residual seed crystal 5 as a nucleus is deposited, and the diamond single crystal 6 grows. Although the mechanism by which the diamond single crystal is deposited from the solvent liquid phase containing carbon on the layer of the single crystal diamond of the residual seed crystal 5 of the raw diamond ingot 2 is not exactly known,
Since the temperature difference between the solvent 4 and the seed crystal surface was very small, it is considered that excessively dissolved carbon was precipitated in the liquid phase of the solvent in the metastable state. Actually, as shown in FIG. 3, the diamond single crystal 6 having an epitaxial relationship with the single crystal diamond of the residual seed crystal 5 is deposited over time. FIG. 4 is a diagram showing an example of the structure of a diamond single crystal produced by the method of the present invention.

Most of the raw diamond ingot 2 embedded in the neutral substance 3 is dissolved by the melting treatment, and the seed crystal 5 which is the residual single crystal diamond portion left in the raw diamond ingot 2 in the recrystallization treatment. From this, diamond is epitaxially grown, and recrystallized diamond 7 is formed as a whole in the shape of the original raw diamond ingot. In the dissolution process, most of the raw diamond mass is replaced with the solvent, and in the recrystallization process, the formation area of the solvent gradually decreases. In this example, the solvent 4 remains attached to the tip of the recrystallized diamond 7.

The present invention is basically a method of crystal growth utilizing the principle of the temperature difference growth method. In the present invention, however, a raw material embedded in a neutral substance by contacting a part with a solvent. A part of a diamond lump is dissolved in a solvent and then recrystallized to grow a diamond single crystal.
Basically, the crystal is not grown in the solvent placed on the raw diamond ingot.

The range of the melting and recrystallization temperature region where the single crystal layer, which is a part of the raw diamond ingot, is not completely dissolved varies depending on the type and composition of the solvent, and also varies depending on the pressure. It is not objective to express all of them with concrete numerical values, because they depend on what kind of standard the pressure temperature is based on. The pressure in this example is 5.4 GPa, 1 as the minimum condition of the diamond synthesis region when Ni is used as the solvent as shown in FIG.
It is a value of pressure temperature determined relative to 384 ° C. The melting and recrystallization temperature regions based on the above are shown in FIG.

In FIG. 5, A, B and C are the solvents A and B, respectively.
It represents the minimum temperature at which the raw diamond ingots in B and C melt, and a, b and c are the selected solvents A and B, respectively.
3 shows melting and recrystallization temperature regions determined when B and C are used. In addition, these A, B, C are F
e64-Ni 34% (Invar alloy), Fe50-Co
It is an experimental value corresponding to a 50% alloy and pure Ni. It should be understood that since the composition of the solvent capable of growing the diamond single crystal is wide, their melting and recrystallization temperature regions are different depending on their composition.

Further, since the melting and recrystallization temperature regions are complicated, such as the size of the starting diamond agglomerate and the treatment time, which are complicated even with the same solvent, the temperature range is conceptually shown. The melting and recrystallization temperature range as referred to in the present invention cannot be determined only by the composition of the solvent, and the melting rate also differs depending on the state and size of the starting diamond ingot. Therefore, regarding the melting and recrystallization temperature range, it should be considered as the temperature range in which a part of the single crystal diamond in the raw diamond mass actually remains, rather than being described numerically as to how many times. is there.

[0040]

Embodiments of the present invention will be described below.

(Example 1) In the sample cell shown in FIG. 1, a single crystal diamond having a bottom surface size of about 5 mm and a thickness of about 4 mm and containing a large amount of inclusions was used as a raw diamond mass, and the mass thereof was about 8 mm. It is embedded in a salt molded body which is a neutral substance having a thickness of 4 mm, and the (100) plane has a diameter of 8 mm and a thickness of 2 mm Fe50 wt% -Co50 wt.
% Contacting with solvent, about 6.2 GPa, 1
When it was held at 370 ° C. for 1 hour to perform a melting treatment, and then as a recrystallization treatment, and then kept at the same temperature for 12 hours, a single crystal layer of about 1 mm was left and a new diamond single crystal of about 3 mm was formed thereon. Precipitated. The recrystallized diamond was a homogeneous diamond single crystal with almost no inclusion.

(Embodiment 2) Almost the same single crystal diamond as in Embodiment 1 is used as a raw diamond ingot, and Fe66 is used as a solvent.
wt% -Ni34 wt%, about 5.8 GPa, 13
When the same conditions as in Example 1 were selected except that the treatment was carried out at 200C for 20 hours, a uniform diamond single crystal of about 3.2 mm was obtained on a single crystal diamond of about 0.7 mm. .

(Example 3) Almost the same raw material diamond lump as in Example 1 was used, pure Ni was used as the solvent, and about 6.3 GP was used.
a, Example 1 except holding at 1420 ° C. for 24 hours
When treated under the same conditions, a homogeneous diamond single crystal having almost no inclusion of about 3.4 mm on a single crystal diamond of about 0.4 mm was obtained.

(Example 4) Using the same sample cell as in Example 1, powder diamond was placed on a single crystal having a bottom surface of about 4 mm and a thickness of about 2 mm to a thickness of 4 mm as a raw diamond ingot, and these were formed into a salt compact. Then, the diamond powder was brought into contact with the Ni solvent. The dissolution treatment was performed at about 6 GPa and 1440 ° C. for 2 hours, and the recrystallization treatment was performed at 1420 ° C. for 34 hours. As a result, a new diamond single crystal of about 2 mm was recrystallized on the remaining single crystal diamond of about 1.3 mm.

(Embodiment 5) In a sample cell shown in FIG. 1, powder diamond containing boron in a diameter of about 5 mm and a diameter of about 4 mm in a synthetic single crystal diamond having a bottom size of about 5 mm and a thickness of about 4 mm. Are laminated, and they are 8 mm in diameter and 8 m
The powder diamond portion was placed in contact with a solvent of Fe50wt% -Co50wt%, held at about 6.4GPa, 1380 ° C for 2 hours for dissolution treatment, and subsequently 1360 ° C. Was kept for 24 hours to carry out recrystallization treatment, and then cooled and depressurized. The sample taken out was a new single crystal diamond with a thickness of about 3 mm.
A recrystallized blue diamond single crystal having a thickness of 4 mm was growing, and the portion showed semiconducting conductivity.

Example 6 A single crystal diamond having a bottom surface of about 3 mm and a thickness of about 1.7 mm and a high-purity graphite compact having a diameter of about 3 mm and a thickness of about 3 mm were laminated in the sample cell shown in FIG. Then, the same cell as in Example 5 was charged, and the same solvent as that used in Example 5 was used to carry out dissolution and recrystallization treatment under substantially the same conditions. The thickness of the single crystal diamond charged in advance was about 1 mm. Reduced to about 1.2 on it
mm new diamond single crystal had grown.

(Embodiment 7) A single crystal diamond having a size similar to that of Embodiment 6 has a diameter of about 3 mm and a thickness of about 3 mm.
Of non-diamond carbon powder compacts were laminated. In this carbon powder compact, amorphous carbon containing 99.9% or more of carbon having a mass number of 13 was treated in vacuum at 2400 ° C. for 2 hours or more to increase the proportion of the graphite component in advance. This was placed in the same cells as in Examples 5 and 6, and the same solvent was used to carry out dissolution and recrystallization treatment under almost the same conditions. The thickness of the single-crystal diamond that had been previously placed was about 1 mm. Reduced, about 0.9mm on it
, A new diamond single crystal was growing.

[0048]

According to the method for producing a diamond single crystal of the present invention, it is possible to synthesize a very large number of types of diamond single crystals by selecting the type of raw material diamond ingot, and the capacity of the sample cell to be used can be increased. On the other hand, there are many advantages such as the ability to synthesize a diamond single crystal having a relatively large diameter. That is, (1) If the diamond in the melted portion of the raw diamond mass has a high purity and the content of nitrogen is very small, the recrystallized diamond single crystal has a high purity.
All of the raw diamond ingot, or single crystal diamond left as a seed crystal, or powder diamond, diamond sintered body, graphite, and other non-diamond carbon which are arranged to be melted by laminating on single crystal diamond as a carbon raw material are carbon If the purity is high as viewed from the specific mass number component, a high purity diamond single crystal having the same mass number can be obtained. (2) If the diamond that is dissolved by the melting treatment is semiconductor diamond, a recrystallized diamond single crystal can also be used as a semiconductor to obtain a semiconductor crystal. (3) At least 2 if the raw diamond mass is selected
A smooth joint surface of diamond single crystal of a kind is obtained. (4) The form of the diamond single crystal can be selected more freely than in the temperature difference growth method. And so on. The diamond single crystal obtained by the method of the present invention can be expected to be applied to cutting tools, dies, bonding tools, optical windows such as lasers, semiconductors and the like.

[Brief description of the drawings]

FIG. 1 is a diagram showing a procedure of sample arrangement according to the method of the present invention.

FIG. 2 is a diagram showing changes in a sample during dissolution processing.

FIG. 3 is a diagram showing how a diamond single crystal grows by recrystallization treatment.

FIG. 4 is a diagram showing an example of a diamond single crystal structure obtained by the method of the present invention.

FIG. 5 is a diagram showing an example of a recrystallization temperature region.

[Explanation of symbols]

 1 Cell 2 Raw Diamond Ingot 3 Neutral Substance 4 Solvent 5 Seed Crystal 6 Diamond Single Crystal 7 Recrystallized Diamond

Claims (10)

[Claims] 1. A method for producing a diamond single crystal by recrystallization having a dissolution treatment and a recrystallization treatment, wherein a raw diamond ingot has a single crystal diamond portion in at least a part thereof. Is a process of dissolving the carbon component of the raw diamond ingot in a solvent while leaving at least a part of the single crystal diamond, and the recrystallization treatment is a seed crystal of the single crystal diamond of the raw diamond ingot left by the dissolution treatment. The method for producing a diamond single crystal by recrystallization, which comprises a step of precipitating a carbon component in a solvent to grow a diamond single crystal. 2. The raw diamond ingot is a single crystal diamond, and the recrystallization treatment is performed in a state where a part of the single crystal diamond in the raw diamond ingot is unmelted. A method for producing a diamond single crystal by the recrystallization described. 3. The raw material diamond ingot is a single crystal diamond laminated with a carbon raw material, and the carbon raw material is powder diamond, a diamond sintered body,
At least one or two or more of graphite and non-diamond carbon are laminated on a single crystal diamond, and recrystallization treatment is a state in which all of the carbon raw material is dissolved and at least a part of the single crystal diamond is undissolved. The method for producing a diamond single crystal according to claim 1, wherein 4. At least one of the single crystal diamond, powdered diamond, diamond sintered body, graphite, and non-diamond carbon contains a specific mass number component of carbon in high purity. 2 or 3
The method for producing a diamond single crystal as described in 1. 5. The melting treatment is carried out by embedding the raw diamond ingot in a neutral substance and keeping a part of the raw diamond ingot in contact with a solvent. The neutral substance is a diamond single crystal. The method for producing a diamond single crystal by recrystallization according to claim 1, 2, 3, or 4, which is a solid substance that does not react with a solvent or carbon under growing conditions. 6. The recrystallization is carried out by holding for a certain period of time at a melting temperature in the melting and recrystallization temperature region determined by the solvent composition, the composition and morphology of the starting diamond ingot, and the melting conditions. The method for producing a diamond single crystal according to claim 1, 2, 3, 4, or 5, wherein the treatment is carried out while being kept at a temperature lower than the melting treatment temperature within the temperature range. 7. The melting treatment and the recrystallization treatment are performed by exposing the raw diamond mass to a melting temperature within a melting and recrystallization temperature region determined by a solvent composition, a composition, a morphology and a melting condition of the raw diamond mass. The method is characterized in that the diamond is partially melted, and subsequently the diamond single crystal is allowed to grow spontaneously.
The method for producing a diamond single crystal according to 3, 4, or 5. 8. The recrystallization treatment is a treatment for forming a diamond single crystal having substantially the same size and morphology as the raw material diamond ingot before the melting treatment, and the recrystallized diamond single crystal is 8. A diamond single crystal having a defect concentration, an impurity concentration, etc. different from that of the raw diamond ingot, 8.
The method for producing a diamond single crystal as described in 1. 9. The recrystallization treatment is a treatment for growing a diamond single crystal in a neutral substance after the raw material diamond ingot is melted.
The method for producing a diamond single crystal according to 3, 4, 5, 6, 7 or 8. 10. The recrystallization treatment is a treatment for taking in a carbon component supplemented in a solvent together with a carbon component of a raw diamond ingot dissolved in a solvent and converting them into a diamond single crystal. Claims 1, 2,
The method for producing a diamond single crystal according to 3, 4, 5, 6, 7, 8 or 9.