Single crystal diamond and tool having the same

Abstract

A single crystal diamond in which the atomic number of nitrogen atoms is 1 ppm or more and 2000 ppm or less, the atomic number N of all nitrogen atoms ALL The difference N between the atomic number of nitrogen atoms C centered on C ALL -N C The ratio (N C -N ALL ) / N C of the atomic number N of the nitrogen atoms C centered on C 5 is 1 or more and 10 or less.

Description

Technical Field

[0001] This disclosure relates to single-crystal diamond and tools containing such single-crystal diamond. Background Technology

[0002] Single-crystal diamond is very hard, so it is widely used in industry, except for cutting tools such as precision cutting tools, woodworking tools, or wear-resistant tools such as grinding wheel dressers, wire drawing dies, scribing tools, water jet throttling orifices, and wire guides (Patent Documents 1, 2).

[0003] Existing technical documents Patent documents Patent Document 1: International Publication No. WO2022 / 118461 Patent Document 2: International Publication No. WO2017 / 198662. Summary of the Invention

[0004] In the single-crystal diamond disclosed herein, The nitrogen atom content, expressed as atomic numbers, is between 1 ppm and 2000 ppm, and the total nitrogen atom count is N. ALL The number N of nitrogen atoms at the center of C C The difference N ALL -N C The number of nitrogen atoms N relative to the C center (independent N) C proportion (N) ALL -N C ) / N C 1 or more and 10 5 the following. Attached Figure Description

[0005] Figure 1 This is a schematic cross-sectional view illustrating an example of the configuration of a sample chamber for the manufacture of synthetic single-crystal diamond as described in one manner of this disclosure.

[0006] Figure 2 This is a schematic cross-sectional view of a single-crystal diamond as described in one aspect of this disclosure. Detailed Implementation

[0007] [The problem this disclosure aims to solve] In recent years, the demand for improved tool life has been increasing, and in single-crystal diamond used in tools, there is a pursuit to improve its wear resistance and chipping resistance. It is known that in single-crystal diamond, wear resistance and chipping resistance are improved due to the easy formation of nitrogen atom aggregation, nitrogen atom and pore aggregation, or both (Patent Document 2). However, in the embodiments of Patent Documents 1 and 2, since the annealing temperature (in other words, the maximum heat treatment temperature) is less than 1600°C, it is difficult to sufficiently generate nitrogen atom aggregation, nitrogen atom and pore aggregation, or both. Furthermore, simply increasing the annealing temperature facilitates the reverse phase transformation from diamond to graphite. Therefore, it is difficult to achieve both excellent wear resistance and excellent chipping resistance in single-crystal diamond.

[0008] Therefore, the purpose of this disclosure is to provide a single-crystal diamond with both excellent wear resistance and excellent fracture resistance, and a tool incorporating the single-crystal diamond.

[0009] [Effects of this disclosure] According to this disclosure, a single-crystal diamond with both excellent wear resistance and excellent fracture resistance, as well as a tool incorporating the single-crystal diamond, can be provided.

[0010] [Description of embodiments of this disclosure] The embodiments of this disclosure will be described first.

[0011] (1) In the single-crystal diamond disclosed herein, The nitrogen atom content, expressed as an atomic number, is between 1 ppm and 2000 ppm. The number of nitrogen atoms N ALL The number N of nitrogen atoms at the center of C C The difference N ALL -N C The number N of nitrogen atoms relative to the C center C proportion (N) ALL -N C ) / N C 1 or more and 10 5 the following.

[0012] According to this disclosure, a single-crystal diamond with both excellent wear resistance and excellent fracture resistance, as well as a tool incorporating the single-crystal diamond, can be provided.

[0013] (2) Based on (1) above, the single-crystal diamond may also include an A center. Thus, it is possible to provide a single-crystal diamond with both superior wear resistance and superior chipping resistance, as well as a tool incorporating the single-crystal diamond.

[0014] (3) Based on (1) or (2) above, the single-crystal diamond may also include a B-center. Thus, it is possible to provide a single-crystal diamond with both superior wear resistance and excellent chipping resistance, as well as a tool incorporating the single-crystal diamond.

[0015] (4) Based on any of (1) to (3) above, the single-crystal diamond may also contain NV. 0 The center. Thus, it is possible to provide single-crystal diamond with both superior wear resistance and superior fracture resistance, as well as tools incorporating such single-crystal diamond.

[0016] (5) Based on any of (1) to (4) above, the single-crystal diamond may also contain NV. ― The center. Thus, it is possible to provide single-crystal diamond with both superior wear resistance and superior fracture resistance, as well as tools incorporating such single-crystal diamond.

[0017] (6) Based on any of (1) to (5) above, the single-crystal diamond may also contain H2 centers. Thus, it is possible to provide a single-crystal diamond with both superior wear resistance and excellent chipping resistance, as well as a tool incorporating the single-crystal diamond.

[0018] (7) Based on any of (1) to (6) above, the single-crystal diamond may also contain an H3 center. Thus, it is possible to provide a single-crystal diamond with both superior wear resistance and superior chipping resistance, as well as a tool incorporating the single-crystal diamond.

[0019] (8) Based on any of (1) to (7) above, the single-crystal diamond may also contain an N3 center. Thus, it is possible to provide a single-crystal diamond with both superior wear resistance and superior chipping resistance, as well as a tool incorporating the single-crystal diamond.

[0020] (9) Based on any one of (1) to (8) above, it may also be a single-crystal diamond, wherein the surface of the single-crystal diamond includes a first region, the arithmetic mean height Sa of the first region as specified in JIS B 0681-2:2018 is 3 nm or more, and the maximum height Sz of the first region as specified in JIS B 0681-2:2018 is 60 nm or more. Thus, it is possible to provide a single-crystal diamond with both superior wear resistance and superior chipping resistance, and a tool incorporating the single-crystal diamond.

[0021] (10) Based on any of (1) to (9) above, it is also possible that a modified portion exists in the outer contour of the single-crystal diamond, and in the inner-shell electron excitation spectrum of the modified portion obtained by using electron energy loss spectroscopy of a transmission electron microscope, a π-value exists in the range of 285 eV ± 5 eV for energy loss. * The maximum intensity of the peak Iπ * σ exists in the range of energy loss of 291±5 eV. * The maximum intensity of the peak Iσ * The ratio of Iπ * / Iσ * The percentage of the first carbon atoms N1 relative to the total number N1+N2 constituting amorphous carbon N1 and the number N2 constituting graphite N1+N2, expressed as {N1 / (N1+N2)}×100, is 90% or more. Therefore, it is possible to provide a single-crystal diamond with both superior wear resistance and superior chipping resistance, as well as a tool incorporating this single-crystal diamond.

[0022] (11) The tool disclosed herein is a tool having the single crystal diamond described in (1) to (10) above.

[0023] According to this disclosure, it is possible to provide tools made of single-crystal diamond that possess both excellent wear resistance and excellent fracture resistance.

[0024] (12) Based on (11) above, the tool may also be a cutting tool, a wear-resistant tool, or a grinding tool. Thus, as a tool made of single-crystal diamond that possesses both excellent wear resistance and excellent fracture resistance, for example, wire drawing dies, injection molding nozzles, wire guides, etc., can be provided.

[0025] [Details of the embodiments disclosed herein] The following description, with reference to the accompanying drawings, details a single-crystal diamond, a method for manufacturing single-crystal diamond, a tool, and a specific example of a method for manufacturing the tool, according to one embodiment of the present disclosure (hereinafter also referred to as "this embodiment"). In the accompanying drawings of this disclosure, the same reference numerals denote the same or equivalent parts. Furthermore, dimensional relationships such as length, width, thickness, and depth have been appropriately modified for clarity and simplification of the drawings and do not necessarily represent actual dimensional relationships.

[0026] In this disclosure, the expression "A~B" refers to the upper and lower limits of the range (i.e., above A and below B). When there is no unit recorded in A but only in B, the unit of A is the same as the unit of B.

[0027] In this disclosure, when compounds are represented by chemical formulas, all previously known atomic ratios are included without specifically limiting the atomic ratios, and are not necessarily limited to atomic ratios within the stoichiometric range.

[0028] [Implementation Method 1: Single Crystal Diamond] The following describes a single-crystal diamond according to one embodiment of the present disclosure.

[0029] One embodiment of this disclosure (hereinafter also referred to as "this embodiment") is a single-crystal diamond, wherein, The nitrogen atom content, expressed as an atomic number, is between 1 ppm and 2000 ppm. The number of nitrogen atoms N ALL The number N of nitrogen atoms at the center of C C The difference N ALL -N C The number N of nitrogen atoms relative to the C center C proportion (N) ALL -N C ) / N C 1 or more and 10 5 the following.

[0030] According to this disclosure, a single-crystal diamond possessing both excellent wear resistance and excellent chipping resistance, as well as a tool incorporating such a single-crystal diamond, can be provided. The reasons for this are speculated as follows.

[0031] In the single-crystal diamond of this embodiment, the nitrogen atom content, expressed as an atomic number, is 1 ppm or more and 2000 ppm or less, and the total nitrogen atom number N is... ALL The number N of nitrogen atoms at the center of C C The difference N ALL -N C The number N of nitrogen atoms relative to the C center C proportion (N) ALL -N C ) / N C 1 or more and 10 5 Therefore, in single-crystal diamond, due to the ease with which nitrogen atoms aggregate, nitrogen atoms and pores aggregate, or both, the wear resistance and chipping resistance of single-crystal diamond are improved. Thus, it is possible to provide single-crystal diamond with both excellent wear resistance and excellent chipping resistance, and tools incorporating such single-crystal diamond.

[0032] Furthermore, a "C-center" refers to the position of a carbon atom in a diamond crystal where a nitrogen atom replaces it by one atomic unit. Type Ib diamonds containing "C-centers" exist. Single-crystal diamonds containing C-centers exhibit an infrared absorption spectrum at a wavenumber of 1130 cm⁻¹, as measured by Fourier transform infrared spectroscopy. -1 Absorption peaks are observed in the vicinity (e.g., wavenumber 1130 ± 2 cm⁻¹).

[0033] The "A-center" mentioned later refers to a condensed aggregate composed of two nitrogen atoms covalently bonded together, with each nitrogen atom replacing a carbon atom that constitutes the diamond crystal. Diamond containing an A-center is called type IaA. Single-crystal diamond containing an A-center exhibits an infrared absorption spectrum measured by Fourier transform infrared spectroscopy at a wavenumber of 1282 cm⁻¹. -1 Nearby (e.g., wavenumber 1282±2cm) -1 The absorption peak is shown.

[0034] The "B-center" mentioned later refers to a condensed aggregate consisting of four nitrogen atoms and one atomic pore, with each nitrogen atom replacing a carbon atom that constitutes the diamond crystal. Diamond containing a B-center is called type IaB. Single-crystal diamond containing a B-center exhibits an infrared absorption spectrum measured by Fourier transform infrared spectroscopy at a wavenumber of 1175 cm⁻¹. -1 Nearby (e.g., wavenumber 1175±2cm) -1 The absorption peak is shown.

[0035] The "NV" mentioned later 0 The "center" refers to a composite defect consisting of a void and a nitrogen atom adjacent to that void. (Including NV) 0 The single-crystal diamond at the center exhibits a fluorescence peak near the fluorescence wavelength of 575 nm (e.g., fluorescence wavelength 575 ± 2 nm) in the fluorescence spectrum obtained by irradiating it with excitation light that is about shorter than 575 nm, such as excitation light with a wavelength of 514 nm.

[0036] The "NV" mentioned later - The "center" refers to a composite defect consisting of a void with a negative charge and a nitrogen atom adjacent to that void. This includes NV. - The single-crystal diamond at the center exhibits a fluorescence peak near the fluorescence wavelength of 637 nm (e.g., fluorescence wavelength 637 ± 2 nm) in the fluorescence spectrum obtained by irradiating it with excitation light that is about shorter than 637 nm, such as excitation light with a wavelength of 514 nm.

[0037] The “H2 center” mentioned later refers to a condensed aggregate consisting of a void with a negative charge and two nitrogen atoms adjacent to that void, each nitrogen atom replacing a carbon atom that constitutes the diamond crystal. Single-crystal diamond containing an H2 center exhibits a fluorescence peak near a fluorescence wavelength of 986 nm (e.g., 986 ± 2 nm) in the fluorescence spectrum obtained by irradiating it with excitation light approximately shorter than 986 nm, such as 830 nm.

[0038] The “H3 center” mentioned later refers to a condensed aggregate consisting of a void and two nitrogen atoms adjacent to that void, with each nitrogen atom replacing a carbon atom that constitutes the diamond crystal. Single-crystal diamond containing an H3 center exhibits a fluorescence peak near a fluorescence wavelength of 503 nm (e.g., 503 ± 2 nm) in the fluorescence spectrum obtained by irradiating it with excitation light approximately shorter than 503 nm, such as 457 nm.

[0039] The “N3 center” mentioned later refers to a condensed aggregate consisting of a void and three nitrogen atoms adjacent to that void, each nitrogen atom replacing a carbon atom that constitutes the diamond crystal. In the fluorescence spectrum obtained by irradiating single-crystal diamond with excitation light approximately shorter than 410 nm, such as 325 nm, the diamond exhibits emission peaks in one or both of the following ranges: near a fluorescence wavelength of 415 nm (e.g., 415 ± 2 nm) and between 420 nm and 470 nm.

[0040] (N) ALL -N C ) / N C

[0041] The number of nitrogen atoms N ALL The number N of nitrogen atoms at the center of C C The difference N ALL -N C The number N of nitrogen atoms relative to the C center C proportion (N) ALL -N C ) / N C 1 or more and 10 5 The following. Therefore, the wear resistance and chipping resistance of single-crystal diamond can be improved. (N) ALL -N C ) / N C The lower limit can be above 1.5 or above 2.0. (N) ALL -N C ) / N C The upper limit can be 2.0 × 10 4Below, can be below 19890, or it can be 10. 4 The following can be 10 3 The following can also be 10. 2 The following. (N) ALL -N C ) / N C It can be 1.5 or higher and 10 4 Below, it can also be 2.0 or above and 10. 3 the following.

[0042] In this disclosure, (N) ALL -N C ) / N C It can be determined using the following method. N C 1130cm based on infrared spectroscopy -1 The integrated intensity of the absorption peak was calculated using the method described in the literature "I. Kiflawi, AE Mayer, PM Spear, JAvan Wyk, G. S. Woods, Philos. Mag. B 69 (1994) 1141. and G. S. Woods, JAvan Wyk, AT Collins, Philos. Mag. B 62 (1990) 589." N ALL The N was determined by performing measurements using secondary ion mass spectrometry (SIMS) under the following conditions. Based on the obtained N... C and N ALL Calculated (N) ALL -N C ) / N C .

[0043] (condition) Measuring device: Trade name (model): "IMS-7f", manufactured by CAMECA. Primary ion species: Cesium (Cs+) Primary acceleration voltage: 15kV Detection area: 30 (μmφ) Measurement accuracy: ±40% (2σ).

[0044] Center A

[0045] Single-crystal diamond can also contain A centers (2N). This further improves the wear resistance and chipping resistance of single-crystal diamond.

[0046] In this disclosure, "single-crystal diamond contains an A-center" can be confirmed by measuring the infrared absorption spectrum at a wavenumber of 1282 cm⁻¹ in the Fourier transform infrared spectroscopy method. -1 Nearby (e.g., wavenumber 1282±2cm) -1 The presence of absorption peaks is used to determine this.

[0047] Center B

[0048] Single-crystal diamond can also contain boron centers (4NV). This further improves the wear resistance and chipping resistance of single-crystal diamond.

[0049] In this disclosure, "single-crystal diamond containing a B-center" can be confirmed by measuring the infrared absorption spectrum at a wavenumber of 1175 cm⁻¹ in Fourier transform infrared spectroscopy. -1 Nearby (e.g., wavenumber 1175±2cm) -1 The presence of absorption peaks is used to determine this.

[0050] NV 0 center

[0051] Single-crystal diamond can also contain NV. 0 The center. This further improves the wear resistance and chipping resistance of single-crystal diamond.

[0052] In this disclosure, "single-crystal diamond includes NV" 0 The "center" can be determined by confirming the presence of an emission peak near the fluorescence wavelength of 575 nm (e.g., fluorescence wavelength 575 ± 2 nm) in the fluorescence spectrum obtained by irradiating with excitation light of approximately shorter than 575 nm, such as excitation light with a wavelength of 514 nm.

[0053] NV - center

[0054] Single-crystal diamond can also contain NV. - The center. This further improves the wear resistance and chipping resistance of single-crystal diamond.

[0055] In this disclosure, "single-crystal diamond includes NV" -The "center" can be determined by confirming the presence of an emission peak near the fluorescence wavelength of 637 nm (e.g., fluorescence wavelength 637 ± 2 nm) in the fluorescence spectrum obtained by irradiating with excitation light that is approximately shorter than 637 nm, such as excitation light with a wavelength of 514 nm.

[0056] H2 Center

[0057] Single-crystal diamond can also contain H2 centers (2NV). - This further improves the wear resistance and chipping resistance of single-crystal diamond.

[0058] In this disclosure, "single-crystal diamond contains H2 centers" can be determined by confirming the presence of an emission peak near the fluorescence wavelength of 986 nm (e.g., fluorescence wavelength 986 ± 2 nm) in the fluorescence spectrum obtained by irradiating with excitation light of a wavelength shorter than 986 nm, such as 830 nm.

[0059] H3 Center

[0060] Single-crystal diamond can also contain H3 centers (2NV). This further improves the wear resistance and chipping resistance of single-crystal diamond.

[0061] In this disclosure, "single-crystal diamond contains H3 centers" can be determined by confirming the presence of a emission peak near the fluorescence wavelength of 503 nm (e.g., fluorescence wavelength 503 ± 2 nm) in the fluorescence spectrum obtained by irradiating with excitation light of about shorter than 503 nm, such as excitation light with a wavelength of 457 nm.

[0062] Single-crystal diamond can also contain N3 centers (3NV). This further improves the wear resistance and chipping resistance of single-crystal diamond.

[0063] In this disclosure, the condition that "single-crystal diamond contains N3 centers" can be determined by confirming the presence of emission peaks in one or both of the following ranges in the fluorescence spectrum obtained by irradiating with excitation light of about 410 nm, such as 325 nm: near a fluorescence wavelength of 415 nm (e.g., 415 ± 2 nm) and between a fluorescence wavelength of 420 nm and 470 nm.

[0064] Composition of single-crystal diamond

[0065] Figure 2 This is a schematic cross-sectional view of a single-crystal diamond as described in one aspect of this disclosure. Figure 2As shown, a modified portion 27 may also exist on the outer contour of the single-crystal diamond 21 in Embodiment 1.

[0066] There are no particular limitations on the shape of the single-crystal diamond 21, and it can be appropriately selected according to the application. The shape of the single-crystal diamond 21 can also be, for example, a plate, prism, pyramid, frustum of a pyramid, or polyhedron. There are no particular limitations on the size of the single-crystal diamond in Embodiment 1; for example, it can be 0.1 mm. 3 ~1000mm 3 .

[0067] The modified portion 27 may also exist on the outer contour of the single-crystal diamond 21. The modified portion 27 may exist on at least a portion of the outer contour of the single-crystal diamond 21. The modified portion 27 may exist in a manner that covers a portion of the outer contour of the single-crystal diamond 21, or it may exist in a manner that covers the entire outer contour of the single-crystal diamond 21. Alternatively, multiple modified portions 27 may be distributed on the outer contour of the single-crystal diamond 21.

[0068] <Deterioration Section> In the single-crystal diamond of Embodiment 1, the π-value in the inner-shell electron excitation spectrum of the modified portion, obtained by electron energy loss spectroscopy (hereinafter also referred to as "TEM-EELS") using a transmission electron microscope, may be in the range of 285 eV ± 5 eV for energy loss. * The maximum intensity of the peak Iπ * σ exists in the range of energy loss of 291±5 eV. * The maximum intensity of the peak Iσ * The ratio of Iπ * / Iσ * The percentage of the first carbon atom N1 relative to the total number of the first carbon atoms N1 constituting amorphous carbon and the number of the second carbon atoms N2 constituting graphite, N1+N2, is 90% or more, which is 0.15 or more.

[0069] In the inner shell electronic excitation spectrum of the metamorphic section obtained by TEM-EELS, π exists in the range of 285 eV ± 5 eV in terms of energy loss. * The peak originates from the carbon π bond and exists in the range of σ with an energy loss of 291 ± 5 eV. * The peak originates from the carbon σ bond. Compared to Iπ... * / Iσ * A value of 0.15 or higher indicates that in the modified portion of the single-crystal diamond of Embodiment 1, the ratio of carbon π bonds to carbon σ bonds is present at a predetermined amount or higher.

[0070] The carbon atoms having π bonds present in the modified part may also include carbon atoms constituting amorphous carbon (also referred to as "first carbon atoms" in this disclosure) and carbon atoms constituting graphite (also referred to as "second carbon atoms" in this disclosure).

[0071] In the modified portion of the single-crystal diamond according to Embodiment 1, the percentage of the first carbon atoms N1 relative to the total number N1+N2 constituting amorphous carbon N1 and the number N2 constituting graphite N1+N2, denoted as {N1 / (N1+N2)}×100, may be 90% or more. This means that more than 90% of the carbon atoms having π bonds present in the modified portion exist as amorphous carbon. Amorphous carbon has a high laser absorption rate. In particular, amorphous carbon has a higher laser absorption rate for wavelengths of 355nm to 1064nm used in the processing of single-crystal diamond compared to diamond and graphite.

[0072] In the inner-shell electronic excitation spectrum of the metamorphic part of single-crystal diamond obtained by TEM-EELS, if compared with Iπ * / Iσ * If the content of the amorphous carbon on the surface of single-crystal diamond is 0.15 or higher and the percentage {N1 / (N1+N2)}×100 is 90% or higher, then the machinability of single-crystal diamond is improved during laser processing due to the high laser absorption rate of the amorphous carbon present on the surface of the single-crystal diamond. In addition, wear resistance and chipping resistance can be improved in single-crystal diamond.

[0073] In this disclosure, the case where a single-crystal diamond possesses a modified portion is determined by measuring the ratio of Iπ in the inner-shell electronic excitation spectrum of the modified portion using TEM-EELS. * / Iσ * The determination was confirmed by measuring the percentage of the altered part {N1 / (N1+N2)}×100.

[0074] The ratio of Iπ in the inner shell electronic excitation spectrum of the metamorphic part obtained by TEM-EELS * / Iσ * Measurement

[0075] First, the ratio Iπ in the inner-shell electronic excitation spectrum obtained by TEM-EELS of the modified part of single-crystal diamond was measured. * / Iσ * The specific measurement method is as follows.

[0076] Step A1. The single-crystal diamond is cut using an argon ion slicer on a plane parallel to the surface normal to obtain a measurement sample with a thickness of 3-100 nm. The measurement sample is observed at 50,000-500,000x magnification using a transmission electron microscope (TEM, JEM-2100F / Cs, a trademark manufactured by Nippon Electron Ltd.) to obtain a bright-field image of the single-crystal diamond.

[0077] Step A2. Next, in the bright-field image, determine the region corresponding to the altered portion. In the bright-field image, the region corresponding to the altered portion can be identified, for example, by the difference in contrast. The following measurements are performed in the bright-field image in the region corresponding to the altered portion, where the estimated thickness is 3 nm or more.

[0078] Step A3. Starting from the surface corresponding to the modified region, and within a range of 2 nm to 3 nm from the normal direction along the surface of the single-crystal diamond, electron energy loss spectroscopy (EELS) is applied. A 1 nm diameter observation spot is scanned at 100 nm along a direction parallel to the surface of the single-crystal diamond to observe the energy loss (K-edge) associated with the excitation of K-shell electrons of carbon. This yields the inner-shell electron excitation spectrum near 300 eV associated with the excitation of K-shell electrons of carbon at the measurement point.

[0079] Step A4. In the inner-shell electronic excitation spectrum at the measurement point, obtain the π value that exists in the range of 285 eV ± 5 eV with an energy loss. * The maximum intensity of the peak Iπ * σ exists in the range of energy loss of 291±5 eV. * The maximum intensity of the peak Iσ * By using Iπ * Divide by Iσ * Find the ratio Iπ * / Iσ * .

[0080] Step A5. Perform the above measurements at five non-overlapping measurement points. Among all the measurement points at the five points, the ratio of Iπ... * / Iσ * When the value is above 0.15, the ratio of Iπ in the inner shell electronic excitation spectrum obtained by TEM-EELS is used to determine the region as equivalent to the metamorphic part. * / Iσ * It is above 0.15.

[0081] Determination of the percentage of altered parts {N1 / (N1+N2)}×100

[0082] Step B1. Next, following steps A1 to A4 above, and setting the judgment to be greater than Iπ... * / Iσ * At each of the five measuring points corresponding to the metamorphic region with a value of 0.15 or higher, π was measured. * The peak states were separated into peaks originating from amorphous carbon and peaks originating from graphite. The five measurement points are the same as the five measurement points set in step A5 above.

[0083] Step B2. At each measurement point, based on the state separation results, obtain the value relative to the maximum intensity Iπ. * The percentage of the first carbon atom N1, which constitutes amorphous carbon, and the second carbon atom N2, which constitute graphite, in the total energy loss is {N1 / (N1+N2)} × 100.

[0084] At all five measurement points, if the percentage {N1 / (N1+N2)}×100 is 90% or higher, the region corresponding to the metamorphic part is determined to be 90% or higher. That is, the region corresponding to the metamorphic part determined in step B1, with a ratio of Iπ in the inner shell electronic excitation spectrum obtained by TEM-EELS, is considered to be the region with the highest degree of metamorphism. * / Iσ * If the value is 0.15 or higher, and the percentage {N1 / (N1+N2)}×100 is 90% or higher, it is determined to be equivalent to a metamorphic part, confirming the existence of a metamorphic part in the outer contour of the single crystal diamond of the test object.

[0085] Furthermore, it was confirmed that as long as the same single-crystal diamond is used for measurement, even if multiple distinct bright-field images are obtained and the measurement points in the regions corresponding to the metamorphic parts are changed in each bright-field image, the measurement results show almost no deviation.

[0086] In the metamorphic portion of the single-crystal diamond in Embodiment 1, compared to Iπ * / Iσ * It can be 0.15 or higher, or 0.17 or higher, or 0.19 or higher.

[0087] In the modified portion of the single-crystal diamond in Embodiment 1, the percentage {N1 / (N1+N2)}×100 can be 90% or more, 93% or more, 96% or more, or 99% or more.

[0088] composition

[0089] <Nitrogen Atom> In the single-crystal diamond of this embodiment, the nitrogen atom content, in terms of atomic number, is 1 ppm or more and 2000 ppm or less. If this content is less than 1 ppm, the wear resistance and chipping resistance of the single-crystal diamond tend to become insufficient because it is difficult for nitrogen atoms to aggregate together, for nitrogen atoms to aggregate with pores, or both. On the other hand, if this content exceeds 2000 ppm, the wear resistance and chipping resistance of the single-crystal diamond tend to become insufficient because it is easy to increase lattice defects in the single-crystal diamond. The lower limit of this content can be 3 ppm or more, 10 ppm or more, 15 ppm or more, or 30 ppm or more. The upper limit of this content can be 1400 ppm or less, 879 ppm or less, 800 ppm or less, or 300 ppm or less.

[0090] In the single-crystal diamond of this embodiment, the atomic percentage of nitrogen atoms can be determined by secondary ion mass spectrometry (SIMS).

[0091] Arithmetic mean height Sa and maximum height Sz

[0092] Alternatively, the surface of the single-crystal diamond in Embodiment 1 may include a first region, wherein the arithmetic mean height Sa of the first region as specified in JIS B0681-2:2018 is 3 nm or more, and the maximum height Sz of the first region as specified in JIS B 0681-2:2018 is 60 nm or more. This improves wear resistance and chipping resistance. Furthermore, since the surface of the single-crystal diamond has a moderate degree of unevenness, the adhesion between the single-crystal diamond and the bonding material is increased when the single-crystal diamond is fixed to the substrate via a bonding material.

[0093] The lower limit of the arithmetic mean height Sa of the first region, from the viewpoint of improving the adhesion between the single-crystal diamond and the bonding material, can be 3 nm or more. The upper limit of the arithmetic mean height Sa of the first region, from the viewpoint of the ease of material setting, can be 100 nm or less. The arithmetic mean height Sa of the first region can be 5 nm or more and 80 nm or less, 5 nm or more and 60 nm or less, or 5 nm or more and 40 nm or less.

[0094] The lower limit of the maximum height Sz of the first region, from the viewpoint of improving the adhesion between the single-crystal diamond and the bonding material, is 60 nm or more. The upper limit of the maximum height Sz of the first region, from the viewpoint of ease of material setting, can be 500 nm or less. The maximum height Sz of the first region can be 80 nm or more and 400 nm or less, or it can be 100 nm or more and 300 nm or less.

[0095] JIS B 0681-2:2018 (Geometrical product specifications (GPS) - Surface texture: Areal - Part 2: Terms, definitions and surface texture parameters) specifies the arithmetic mean height Sa and maximum height Sz as defined in ISO 25178-2:2012 (Geometrical product specifications (GPS) - Surface texture: Areal - Part 2: Terms, definitions and surface texture parameters (MOD)).

[0096] In this disclosure, the fact that the surface of a single-crystal diamond includes a first region is confirmed by the following steps.

[0097] The surface of a single-crystal diamond is divided into rectangular unit regions of 10 μm × 10 μm. Within each unit region, the arithmetic mean height Sa and the maximum height Sz are measured. Depending on the shape of the single-crystal diamond surface, there may be cases where the surface cannot be divided into integer unit regions, resulting in surplus. In such cases, only the unit regions are measured, and the surplus regions are removed from the measurement scope.

[0098] In the presence of unit regions with an arithmetic mean height Sa greater than 3 nm and a maximum height Sz greater than 60 nm, it was confirmed that the surface of the single-crystal diamond includes a first region. The area of ​​the first region is 100 μm. 2 above.

[0099] In this disclosure, the arithmetic mean height Sa and the maximum height Sz of the first region are determined by the following steps: On the surface of a single-crystal diamond, all unit regions A with an arithmetic mean height Sa of 3 nm or more and a maximum height Sz of 60 nm or more are identified. Based on all unit regions A, the arithmetic mean height Sa and the maximum height Sz are measured. The unit regions A may or may not be in contact with each other. In this disclosure, the arithmetic mean height Sa measured based on all unit regions A is equivalent to the arithmetic mean height Sa of the first region. In this disclosure, the maximum height Sz measured based on all unit regions A is equivalent to the maximum height Sz of the first region.

[0100] In this disclosure, the position and size of the first region on the surface of the single-crystal diamond can be appropriately set according to the application of the single-crystal diamond. For example, when the single-crystal diamond is fixed to the substrate by a bonding material, the first region can constitute at least a portion of the area in contact with the bonding material on the surface of the single-crystal diamond. Furthermore, the first region can constitute the entire surface of the single-crystal diamond. The proportion of the first region to the entire surface of the single-crystal diamond can be, for example, 25% or more, 50% or more, or even 100%.

[0101] Methods for manufacturing single-crystal diamond

[0102] use Figure 1 The method for manufacturing single-crystal diamond disclosed herein will be described. Figure 1 This is a schematic cross-sectional view illustrating an example of the configuration of a sample chamber used in the manufacture of synthetic single-crystal diamond according to one embodiment of the present disclosure. The method for manufacturing single-crystal diamond according to one embodiment of the present disclosure includes a step of obtaining a diamond single crystal using a temperature difference method with a solvent metal (hereinafter also referred to as the "temperature difference method step"), a step of irradiating the diamond single crystal with an electron beam (hereinafter also referred to as the "irradiation step"), a step of annealing the diamond single crystal irradiated with the electron beam (hereinafter also referred to as the "annealing step"), and a step of performing acid treatment on the annealed diamond single crystal (hereinafter, the "acid treatment step").

[0103] <Temperature Difference Method Process> Diamond single crystals, for example, can be used with Figure 1 The sample chamber shown is fabricated using the temperature difference method.

[0104] like Figure 1 As shown, in the sample chamber 10 used for manufacturing diamond single crystals, an insulator 2, a carbon source 3, a solvent metal 4, and a seed crystal 5 are arranged within the space enclosed by a graphite heater 7, and a pressure medium 6 is arranged outside the graphite heater 7. The temperature difference method refers to setting a longitudinal temperature gradient inside the sample chamber 10, with a high-temperature section (T...)... high Carbon source 3 is configured in the low-temperature section (T) low A synthesis method for growing diamond single crystals on seed crystal 5 by preparing a diamond seed crystal 5, placing a solvent metal 4 between a carbon source 3 and seed crystal 5, and maintaining the condition at a pressure above the temperature at which the solvent metal 4 dissolves so that the diamond becomes thermally stable.

[0105] Diamond powder can be used as the carbon source 3. Alternatively, graphite or thermally decomposed carbon can also be used. As the solvent metal 4, one or more metals selected from iron (Fe), cobalt (Co), nickel (Ni), and manganese (Mn), or alloys containing these metals, can be used.

[0106] In the carbon source 3 or solvent metal 4, nitrogen supply sources can be provided, for example, by adding nitrides such as iron nitride (Fe2N, Fe3N), aluminum nitride (AlN), phosphorus nitride (P3N4), and silicon nitride (Si3N4), as well as organic nitrogen compounds such as melamine and sodium azide as monomers or mixtures. Thus, nitrogen atoms are present in the synthesized diamond single crystal. In this case, the nitrogen atoms in the diamond single crystal mainly exist as independently substituted nitrogen atoms.

[0107] The content of nitrogen supply source in carbon source 3 or solvent metal 4 can be set, for example, such that the content of nitrogen atoms from the nitrogen supply source in the carbon source is 1 ppm or more and 5000 ppm or less on an atomic basis. Furthermore, in the solvent metal, for example, if the solvent metal is an alloy composed of iron-cobalt-nickel and the nitrogen supply source is Fe3N, the content of the nitrogen supply source can be set to 0.01% by mass or more and 10% by mass or less.

[0108] Solvent metal 4 may also include one or more elements selected from the group consisting of titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), copper (Cu), zirconium (Zr), niobium (Nb), molybdenum (Mo), ruthenium (Ru), rhodium (Rh), hafnium (Hf), tantalum (Ta), tungsten (W), osmium (Os), iridium (Ir), and platinum (Pt).

[0109] <Irradiation Process> Next, the obtained diamond single crystal is processed to a thickness of 0.1 mm or more and less than 10 mm, for example, with a size of 10 mm square. Then, lattice defects are introduced into the diamond single crystal by irradiating it with an electron beam, forming voids.

[0110] The electron beam irradiation conditions can be set to an energy of 1.0 MeV or higher and 10 MeV or lower, and a dose of 1.0 × 10⁻⁶. 19 e / m 2 Above and 1.0×10 23 e / m 2 The area irradiated by the electron beam is larger than the area (region) irradiated by the electron beam in diamond single crystals. If the energy and dose of the electron beam are less than the lower limit mentioned above, there is a risk of insufficient introduction of lattice defects. Conversely, if the upper limit is exceeded, there is a risk of generating excessive voids and a significant reduction in crystallinity.

[0111] <Annealing process> Next, the diamond single crystal irradiated with the electron beam will be subjected to a 10-fold increase in temperature in a vacuum or in an inert gas atmosphere. -3 Annealing is performed at a pressure of 1600°C to 1800°C and a pressure of 0.2 MPa to 1 Pa. The heating rate up to the maximum temperature is set to 1°C / min to 3°C / min. Then, cooling is performed at a cooling rate of 0.5°C / min to 5°C / min. This causes independently substituted nitrogen atoms within the diamond single crystal to move through the pores, creating condensed nitrogen defects. The annealing time can be set to 10 minutes to 1000 minutes.

[0112] If the annealing temperature is below 1600°C, the annealing process becomes insufficient due to the slower nitrogen migration rate, which is undesirable. On the other hand, if the annealing temperature exceeds 1800°C, the nitrogen migration rate increases, and the diamond single crystal graphitizes under normal pressure. Therefore, annealing at temperatures exceeding 1800°C requires thermodynamically stable ultra-high pressure conditions, which is undesirable from the perspective of increased cost and reduced productivity.

[0113] The irradiation and annealing processes can be repeated two or more times, each performed once. This promotes the movement of independently substituted nitrogen atoms within the diamond single crystal. By sufficiently performing the irradiation and annealing processes, a sufficient amount of condensed nitrogen defects are generated from independently substituted nitrogen atoms in the diamond single crystal.

[0114] <Acid Treatment Process> Next, the annealed diamond single crystal is immersed in acid to perform acid treatment. The acid used in the acid treatment process is a mixed solution of concentrated sulfuric acid and concentrated nitric acid. The acid treatment time is 5 minutes or more, but can also be 300 minutes or less. The acid temperature can also be above room temperature and below 300°C.

[0115] <Features of the method for manufacturing single-crystal diamond according to this embodiment> In this embodiment, the manufacturing of single-crystal diamond is performed under the following conditions: "In the irradiation process, the electron beam irradiation conditions are set to an electron beam energy of 1.0 MeV or higher and 10 MeV or lower, and a dose of 1.0 × 10⁻⁶." 19 e / m 2 Above and 1.0×10 23 e / m 2 The following, "In the annealing process, with 10" -3"Annealing is performed under pressures of 1600°C to 1800°C or higher," "In the annealing process, annealing is performed at a temperature of 1°C to 10°C or higher and a cooling rate of 0.5°C to 5°C or lower" (in other words, slow heating and slow cooling), and "An acid treatment process is performed by immersion in a mixed solution of concentrated sulfuric acid and concentrated nitric acid for 5 minutes or more." Through these methods, even when the nitrogen atom content is low (in other words, the nitrogen atom content is 1 ppm to 2000 ppm or higher), it is possible to achieve "a total nitrogen atom number N". ALL The number N of nitrogen atoms at the center of C C The difference N ALL -N C The number N of nitrogen atoms relative to the C center C proportion (N) ALL -NC) / N C 1 or more and 10 5 The following is the reason for this speculation.

[0116] (i) In the method for manufacturing single-crystal diamond according to this embodiment, the electron beam irradiation conditions are set to an electron beam energy of 1.0 MeV or more and 10 MeV or less, and a dose of 1.0 × 10⁻⁶. 19 e / m 2 Above and 1.0×10 23 e / m 2 The following, "In the annealing process, with 10" -3 Annealing at a pressure of 1600°C to 1800°C or higher, or at a pressure of 0.2 MPa or lower, or annealing at a temperature of 1600°C to 1800°C or higher, can promote the aggregation of nitrogen atoms, the aggregation of nitrogen atoms and pores, or both. For example, in Patent Document 2, the temperature in the annealing process is less than 1600°C, so it is difficult to sufficiently promote the aggregation of nitrogen atoms, the aggregation of nitrogen atoms and pores, or both.

[0117] (ii) However, by “in the irradiation process, the irradiation conditions of the electron beam are set to an energy of 1.0 MeV or higher and 10 MeV or lower, and a dose of 1.0 × 10 19 e / m 2 Above and 1.0×10 23 e / m 2 The following, "In the annealing process, with 10" -3Annealing at a pressure of 1600°C to 1800°C or higher, and annealing at a temperature of 1600°C to 1800°C or higher, can promote nitrogen aggregation. However, due to the high temperature of the annealing process, there is a tendency for an inverse phase transition from diamond to graphite to occur. Therefore, in order to produce the single-crystal diamond according to this embodiment, it is necessary to suppress the occurrence of this inverse phase transition.

[0118] (iii) In the method for manufacturing single-crystal diamond according to this embodiment, by “making the heating rate at 1°C / min or more and 3°C / min or less, and the cooling rate at 0.5°C / min or more and 5°C / min or less” (in other words, heating up and cooling down slowly), it is difficult for the “reverse phase transition from diamond to graphite” caused by the high temperature of the annealing process to occur. Therefore, the amount of graphite generated on the surface of single-crystal diamond can be suppressed to a small extent.

[0119] (iv) In the method for manufacturing single-crystal diamond according to this embodiment, graphite generated on the surface of single-crystal diamond can be removed by "an acid treatment process in which the diamond is immersed in a mixed solution of concentrated sulfuric acid and concentrated nitric acid for more than 5 minutes". (In other words, graphite that is at least suppressed in (iii) above)

[0120] The single-crystal diamond disclosed herein, produced by the above manufacturing method, is a new discovery made through in-depth research by the inventors.

[0121] [Implementation Method 2: Tools] The tools involved in this embodiment will be described.

[0122] This embodiment is a tool equipped with the single-crystal diamond described in Embodiment 1.

[0123] According to this disclosure, it is possible to provide tools made of single-crystal diamond with excellent wear resistance.

[0124] tool

[0125] Examples of tools involved in this embodiment include, for instance, dressers, wire drawing dies, surgical scalpels, injection molding nozzles, wire guides, scribing tools, water jet throttling orifices, precision machining lathe tools, woodworking tools, and grinding wheels. Thus, wear-resistant tools, cutting tools, and grinding tools can be provided as tools made from single-crystal diamond with excellent wear resistance.

[0126] Tool manufacturing methods

[0127] The tool manufacturing method described in this embodiment can be performed using conventionally known methods, except that it uses single-crystal diamond as the material of the tool as described in Embodiment 1.

[0128] Example The present embodiment will be further described in detail through examples. However, the present embodiment is not limited to these examples.

[0129] Production of single-crystal diamond

[0130] The single-crystal diamonds involved in samples 1 to 14 were fabricated as follows.

[0131] <Temperature Difference Method Process> First, using Figure 1 The sample chamber shown was used to synthesize diamond single crystals by using the temperature difference method with solvent metal.

[0132] As a solvent metal, an alloy composed of iron, cobalt, and nickel was prepared, and iron nitride (Fe3N) powder was added to it as a nitrogen supply source. The concentration of iron nitride (Fe3N) in the solvent metal is recorded in Table 1, “Concentration of iron nitride in solvent metal [mass %]”.

[0133] Diamond powder was used as the carbon source, and diamond single crystals of the mass listed in Table 1 were used as the seed crystals. The temperature in the sample chamber was adjusted by a heater to create a temperature difference of several tens of degrees between the high-temperature section containing the carbon source and the low-temperature section containing the seed crystal. Based on this, diamond single crystals were synthesized on the seed crystals by maintaining the temperature at 5.5 GPa and 1370℃ ± 10℃ (1360℃ ~ 1380℃) for 100 hours using an ultra-high pressure generator.

[0134] <Irradiation Process> Next, with "Yes" recorded in the "Presence or absence of electron beam irradiation" column of Table 1, the obtained diamond single crystal was irradiated with an electron beam (electron beam energy: as recorded in Table 1. electron beam dose: as recorded in Table 1).

[0135] <Annealing process> Next, with "Yes" recorded in the "Presence or absence of heat treatment" column of Table 2, the diamond single crystal after the irradiation process was subjected to an annealing process under vacuum and normal pressure, according to the conditions recorded in Table 2.

[0136] <Acid Treatment Process> Next, single-crystal diamond was obtained by acid treatment of the annealed diamond single crystal with a mixed solution of concentrated sulfuric acid and concentrated nitric acid for 30 minutes. In the mixed solution, the ratio of concentrated sulfuric acid (95% by mass) to concentrated nitric acid (60% by mass) was 3:1 on a volume basis.

[0137] Through the above steps, the single-crystal diamonds involved in Samples 1 to 14 were produced.

[0138] Evaluation of the properties of single-crystal diamond

[0139] <Natural atom content> For the single-crystal diamonds involved in each sample, the nitrogen atom content (in terms of atomic number) was determined using the method described in Example 1. The results were entered in the "Nitrogen Atom Content [ppm]" column of Table 3.

[0140] < (N) ALL -N C ) / N C > For the single-crystal diamonds involved in each sample, the number N of total nitrogen atoms was determined using the method described in Example 1. ALL The number N of nitrogen atoms at the center of C C The difference N ALL -N C The number N of nitrogen atoms relative to the C center C proportion (N) ALL -N C ) / N C Record the results in Table 3, "(N)". ALL -N C ) / N C "column.

[0141] <The presence or absence of center A> For each sample of single-crystal diamond, the presence or absence of center A was determined using the method described in Embodiment 1. The results were recorded in the "Presence or Absence of Center A" column of Table 3.

[0142] <The presence or absence of Center B> For each sample of single-crystal diamond, the presence or absence of the B-center was determined using the method described in Embodiment 1. The results were recorded in the "Presence or Absence of B-center" column of Table 3.

[0143] <NV 0 The presence or absence of a center > For the single-crystal diamonds involved in each sample, NV was determined using the method described in Embodiment 1. 0The presence or absence of a center. Record the results in Table 3, "NV". 0 The "Availability of Center" column.

[0144] <NV - The presence or absence of a center > For the single-crystal diamonds involved in each sample, NV was determined using the method described in Embodiment 1. - The presence or absence of a center. Record the results in Table 3, "NV". - The "Availability of Center" column.

[0145] <The presence or absence of the H2 center> For each sample of single-crystal diamond, the presence or absence of H2 centers was determined using the method described in Embodiment 1. The results were recorded in the "Presence or Absence of H2 Centers" column of Table 3.

[0146] <The presence or absence of H3 center> For each sample of single-crystal diamond, the presence or absence of the H3 center was determined using the method described in Embodiment 1. The results were recorded in the "Presence or Absence of H3 Center" column of Table 3.

[0147] <The presence or absence of N3 center> For each sample of single-crystal diamond, the presence or absence of the N3 center was determined using the method described in Embodiment 1. The results were recorded in the "Presence or Absence of N3 Center" column of Table 3.

[0148] <Abrasion Resistance Evaluation Test> Using each cutting tool made with the single-crystal diamond involved in each test sample (cage: CSRP R3225-N12, insert: SPGN120308, tool with the aforementioned single-crystal diamond at the tip of the insert), the outer diameter of the workpiece was machined using this cutting tool under the following cutting conditions, and the cutting distance [km] until the average flank wear of the cutting tool reached 200 μm was measured. The results were recorded in the "Cutting Distance [km]" column of the "Wear Resistance Test" section in Table 4. A longer cutting distance [km] indicates better wear resistance.

[0149] (Cutting conditions) Workpiece to be machined: Ti-6Al-4V (φ120mm×280mm) Cutting speed: 250 m / min Feed rate: 0.1 mm / rev Cut depth: 0.4mm coolant: wet <Crack resistance evaluation test> Using each of the single-crystal diamonds involved in each test, a turning insert as specified in catalog number "NF-DNMA150408" (Sumitomo Electric Industries, Ltd.) was prepared. Next, the workpiece was cut using this turning insert under the following cutting conditions. Cutting was stopped at the point where the chipping size at the cutting tip of the turning insert exceeded 0.1 mm, and the time (in minutes) from the start of the test to that point was measured. The results were recorded in the "Time (minutes)" column of the "Chipping Resistance Test" section of Table 4. A longer time (in minutes) indicates better chipping resistance.

[0150] (Cutting conditions) Workpiece to be machined: cemented carbide (VM-40 (dimensions: diameter φ60mm × length 100mm), hardness: HRA88) Processing machine: spinning disc Cutting speed Vc: 10m / min Feed rate f: 0.05 mm / rev Cut-in depth (ap): 0.05mm / rev Cutting oil (coolant): None [Table 1]

[0151] [Table 2]

[0152] [Table 3]

[0153] [Table 4]

[0154] The single-crystal diamonds involved in samples 7 to 14 are equivalent to the examples. The single-crystal diamonds involved in samples 1 to 6 are equivalent to the comparative examples. According to the results in Table 1, the single-crystal diamonds involved in samples 7 to 14 have both excellent wear resistance and excellent chipping resistance compared with the single-crystal diamonds involved in samples 1 to 6.

[0155] As can be seen from the above, the single-crystal diamonds involved in samples 7-14 possess both excellent wear resistance and excellent fracture resistance.

[0156] The embodiments and examples of this disclosure have been described above, but it is also intended from the outset that the above-described embodiments and examples may be appropriately combined or modified.

[0157] The embodiments and examples disclosed herein should be considered exemplary in all respects, and not restrictive. The scope of the invention is defined not by the foregoing embodiments and examples, but by the claims, and is intended to include all modifications equivalent to and within the scope of the claims.

[0158] Explanation of reference numerals in the attached figures: 1: Single crystal diamond; 2: Insulator; 3: Carbon source; 4: Solvent metal; 5: Seed crystal; 6: Pressure medium; 7: Graphite heater; 21: Single crystal diamond; 27: Modified part.

Claims

1. A single-crystal diamond, wherein, The nitrogen atom content, expressed as an atomic number, is between 1 ppm and 2000 ppm. The number of nitrogen atoms N ALL The number N of nitrogen atoms at the center of C C The difference N ALL -N C The number N of nitrogen atoms relative to the C center C proportion (N) ALL -N C ) / N C 1 or more and 10 5 the following.

2. The single-crystal diamond according to claim 1, wherein, The single-crystal diamond contains an A center.

3. The single-crystal diamond according to claim 1 or 2, wherein, The single-crystal diamond contains a B-center.

4. The single-crystal diamond according to any one of claims 1 to 3, wherein, The single-crystal diamond contains NV. 0 center.

5. The single-crystal diamond according to any one of claims 1 to 4, wherein, The single-crystal diamond contains NV. - center.

6. The single-crystal diamond according to any one of claims 1 to 5, wherein, The single-crystal diamond contains H2 centers.

7. The single-crystal diamond according to any one of claims 1 to 6, wherein, The single-crystal diamond contains an H3 center.

8. The single-crystal diamond according to any one of claims 1 to 7, wherein, The single-crystal diamond contains an N3 center.

9. The single-crystal diamond according to any one of claims 1 to 8, wherein, The surface of the single-crystal diamond includes a first region. The arithmetic mean height Sa of the first region, as specified in JIS B 0681-2:2018, is 3 nm or more. The maximum height Sz of the first region is 60 nm or more, as specified in JIS B 0681-2:2018.

10. The single-crystal diamond according to any one of claims 1 to 9, wherein, The outer contour of the single-crystal diamond contains altered portions. In the inner shell electron excitation spectrum of the modified part obtained by electron energy loss spectroscopy using transmission electron microscopy, π exists in the range of energy loss of 285 eV ± 5 eV. * The maximum intensity of the peak Iπ * σ exists in the range of energy loss of 291±5 eV. * The maximum intensity of the peak Iσ * The ratio of Iπ * / Iσ * Above 0.15 In the modified section, the percentage of the first carbon atoms N1 relative to the total number N1 constituting amorphous carbon and the number N2 constituting graphite N1+N2, which is the number of first carbon atoms N1 and the number of second carbon atoms N2 constituting graphite, is 90% or more.

11. A tool, wherein, The tool comprises the single-crystal diamond as described in any one of claims 1 to 10.

12. The tool according to claim 11, wherein, The tool is a cutting tool, a wear-resistant tool, or a grinding tool.

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