JP2010024506A - Method for producing boron-doped diamond, boron-doped diamond, and electrode - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing boron-doped diamond by which boron-doped diamond particles can be easily produced, to provide a boron-doped diamond, and to provide an electrode. <P>SOLUTION: The method for producing the boron-doped diamond is characterized in that the boron-doped diamond is grown on the surface of a substrate, where tungsten or its oxide is exposed at least a portion of the surface. The surface roughness of the substrate is preferably ≤0.5 μm. As the substrate, a substrate wherein areas composed of tungsten or its oxide and areas free of tungsten exist in a mixed state can be used. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a method for producing boron-doped diamond that can be applied to, for example, an electrode, a boron-doped diamond, and an electrode.

Boron-doped diamond (hereinafter referred to as boron-doped diamond) is electrically conductive and can be used for electrodes for industrial electrolysis and electrochemical sensors. Boron-doped diamond is easier to emit electrons than insulator diamond, and its application to field electron emission devices is also being studied. In particular, powder (particulate) boron-doped diamond is easy to mold and has a large surface area, so the application range is widened. The following methods are conceivable as methods for producing powdered boron-doped diamond.
(1) A method for obtaining conductive diamond particles by pulverizing a lump of diamond produced by a high-temperature and high-pressure method, as in the method for producing diamond abrasive grains (see Patent Documents 1 to 3). Specifically, graphite containing boron in an amount of 0.5 wt% or more and 15 wt% or less and a diamond conversion metal catalyst are allowed to coexist at a temperature of 1200 ° C. or higher and a pressure of 4.5 GPa or higher at a high temperature and a high pressure. When converted, a diamond aggregate having a diameter of 7 mm in which fine particles of 20 to 30 μm are aggregated is obtained. The diamond aggregate is crushed with a mortar to produce diamond particles.
(2) A method of directly forming a diamond film on the surface of a particulate material by a microwave plasma CVD (Chemical Vapor Deposition) method. A batch system using a fluidized bed (see Patent Documents 4 to 5) and a system (see Patent Document 6) using rotation and gradient of a rotating reaction vessel are disclosed. Specifically, a heat-resistant metal powder such as tungsten or molybdenum, or a ceramic powder such as silicon carbide, tungsten carbide, or diamond is placed in the plasma generation chamber as a diamond deposition material. Conductive diamond is deposited on the surface of the diamond deposition material by maintaining the diamond deposition material in a fluidized state by powder flow means such as a fluidized bed method, a vibrating bed method, and a moving bed method, and exciting the plasma in the fluidized bed. To obtain a powder.
(3) Diamond is deposited on the nucleated silicon wafer, then silicon is dissolved with hydrofluoric acid or the like to obtain self-supporting diamond, and then pulverized with a mortar or the like to obtain conductive diamond particles. How to manufacture.
Japanese Patent No. 3398759 JP-A-2005-290403 WO2005 / 065809 Japanese Patent Publication No. 60-57568 JP-A-63-270394 Japanese Patent No. 2697559

  In the method (1), impurities such as iron and cobalt, which are metal catalysts, are mixed in the obtained conductive diamond particles, so that washing with a strong acid such as aqua regia is required as a post-treatment, The process for producing the conductive diamond becomes complicated.

  In order to obtain conductive diamond particles, a diamond aggregate having a diameter of 7 mm must be pulverized. However, pulverizing high-hardness diamond requires a great amount of labor. Since it becomes a mixture of various diamond particles, a complicated refining operation is required to obtain diamond particles having a predetermined particle size.

  In the method (2), since the plasma is irradiated from the upper surface of the diamond deposition material placed on the substrate holder in the plasma generation chamber, a conductive diamond layer is deposited on the entire surface of the diamond deposition material as it is. It is difficult. As a method for solving this, a method using a fluidized bed of diamond deposition material and a method incorporating a mechanism for continuously supplying powder of diamond deposition material have been devised, but particles having a particle size of several μm or less are agglomerated. It is easy to form, and it is difficult to form a diamond film uniformly. Furthermore, if the reaction vessel is rotated, it becomes difficult to stably maintain the plasma, and it is necessary to adjust the powder of the diamond deposition material exposed to the plasma to be located on the same plane. It becomes difficult to adjust the manufacturing conditions.

  In the method (3), silicon used as a substrate cannot be regenerated, and an operation for dissolving silicon takes a long time. Furthermore, since a strong fluorine-based acid is used for dissolving silicon, the environmental load increases.

  This invention is made | formed in view of the above point, and it aims at providing the manufacturing method of boron dope diamond, the boron dope diamond, and electrode which can make manufacture of boron dope diamond particle | grains easy.

(1) The invention of claim 1
The gist of the present invention is a method for producing boron-doped diamond, characterized in that a CVD method is used to grow boron-doped diamond on a substrate on which tungsten or an oxide thereof is exposed at least at a part of the surface.

  In the present invention, since tungsten or its oxide is exposed on the surface of the substrate, boron-doped diamond can be grown at least in that portion. For example, as shown in FIG. 2A, flaky boron-doped diamond 103 can be grown on the surface of a substrate 101 made of tungsten.

The flaky boron-doped diamond 103 can be easily separated from the substrate 101 by, for example, cooling the substrate 101 to room temperature. The flaky boron-doped diamond 103 can be easily pulverized into a powder having a uniform particle size. Therefore, if this invention is used, the powder of boron dope diamond can be manufactured easily.
(2) The invention of claim 2
The gist of the method for producing boron-doped diamond according to claim 1, wherein the surface roughness of the substrate is 0.5 μm or less.

  In the present invention, since the surface roughness (Ra) of the substrate is 0.5 μm or less, the boron-doped diamond grown on the substrate can be easily separated from the substrate. Therefore, it becomes easier to produce boron-doped diamond and its powder.

The lower limit of the surface roughness (Ra) of the substrate is not particularly limited in terms of ease of peeling of the boron-doped diamond. If the surface roughness (Ra) of the substrate is 0.01 μm or more, it is easy to finish the surface of the substrate.
(3) The invention of claim 3
The gist of the boron-doped diamond manufacturing method according to claim 1, wherein a region made of tungsten or an oxide thereof and a region not containing tungsten are mixed on the surface of the substrate.

  According to the present invention, boron-doped diamond powder can be more easily produced. That is, as shown in FIG. 2B, boron-doped diamond is formed on a substrate 201 (for example, a sintered body of tungsten and titanium) in which a region made of tungsten or its oxide and a region not containing tungsten are mixed. Is grown mainly in a region made of tungsten or an oxide thereof, and the particulate boron-doped diamond 203 corresponding to the size of the region grows locally. The particulate boron-doped diamond 203 can be separated from the substrate 201 by cooling the substrate.

Therefore, according to this invention, the process which grind | pulverizes a boron dope diamond can be abbreviate | omitted, or the process can be simplified, and a particulate boron dope diamond can be manufactured.
As the material constituting the region not containing tungsten, any material that does not easily grow boron-doped diamond compared to tungsten or its oxide can be used widely, and examples thereof include copper, carbon, and titanium. .
(4) The invention of claim 4
After the boron-doped diamond is grown on the substrate, the cooling step of lowering the temperature of the boron-doped diamond and the substrate than that during the growth,
The surface of the substrate on which the boron-doped diamond is grown is inclined with respect to a horizontal direction during the cooling step or after the cooling step. The gist is a method for producing boron-doped diamond.

  In the present invention, if the substrate and the boron-doped diamond are separated during the cooling step, the substrate is inclined with respect to the horizontal direction during the cooling step or after the cooling step, so that the boron-doped diamond slides down from the substrate. .

  Therefore, every time the growth process of boron-doped diamond is completed, the process of opening the CVD chamber and removing the boron-doped diamond from the substrate becomes unnecessary, and the boron-doped diamond can be continuously synthesized. As a result, the productivity of boron-doped diamond is improved.

The cooling step may be natural cooling in which the substrate is allowed to stand at room temperature, or may be one in which the substrate is cooled using a known cooling means.
The substrate may be always inclined, or may be inclined only during the cooling process or after the cooling process.
(5) The invention of claim 5
The gist of the boron-doped diamond produced by the method for producing boron-doped diamond according to claim 1.

Since the boron-doped diamond of the present invention can be made into a flaky shape, it can be easily pulverized into a boron-doped diamond powder. Further, boron-doped diamond powder having a uniform particle size can be obtained.
(6) The invention of claim 6
The gist is an electrode in which a powder made of boron-doped diamond according to claim 5 is carried on the surface of a base material made of a conductive material.

  The electrode of the present invention is excellent in electrochemical characteristics by using the powder made of boron-doped diamond according to claim 5.

  An embodiment of the present invention will be described.

(1) Production of boron-doped diamond Boron-doped diamond was grown on the substrate under the conditions A to R shown in Table 1 using a microwave plasma CVD method.

  In the microwave plasma CVD method, as the carbon source and the boron source, a gas generated by bubbling with hydrogen gas a solution obtained by dissolving boron oxide in a mixed solvent of acetone and methanol (boron solution) was used. The B (boron) / C (carbon) ratio in this boron solution was 10,000 ppm. Further, other film forming conditions in the microwave plasma CVD method were as follows.

Microwave frequency: 2.45 GHz
Microwave plasma output: 8kW
Pressure: 120 Torr
Hydrogen gas: 500sccm
Substrate temperature: 900 ° C
In each condition, the substrate used was the material described in “Substrate” in Table 1 above. “Surface roughness” in Table 1 is the surface roughness (Ra) of the substrate, and the surface roughness 1 is measured in a non-contact manner using a Keyence laser microscope as a measuring device. “Oxygen plasma” in “Surface treatment” in Table 1 is a treatment for forming a tungsten oxide layer by irradiating the surface of a tungsten substrate with oxygen plasma.
Under each condition, the boron-doped diamond was grown for 6 to 12 hours, and the film thickness of the boron-doped diamond under each condition was changed from several μm to several tens of μm. After completion of the step of growing boron-doped diamond, the CVD apparatus was naturally cooled. Thereafter, the boron-doped diamond flakes were removed from the substrate.
(2) Evaluation of boron-doped diamond Whether the boron-doped diamond has grown using the surface observation by scanning electron microscope, Raman spectroscopic measurement, X-ray diffraction measurement, and electrical resistivity measurement by four-terminal method. Confirmed no. When the boron-doped diamond grew, it was evaluated as “◎”, and when it did not grow, it was evaluated as “x”.

Further, the peelability between the boron-doped diamond and the substrate was evaluated according to the following criteria.
◎: Boron-doped diamond and substrate completely peeled off at the end of cooling of the CVD apparatus ○: Boron-doped diamond and substrate almost peeled off at the end of cooling of the CVD apparatus Δ: Boron-doped diamond and substrate at the end of cooling of the CVD apparatus Is partially peeled x: When the cooling of the CVD apparatus is finished, the boron-doped diamond and the substrate are unpeeled and the evaluation results are shown in Table 1 above. As is apparent from Table 1, when the substrate is made of tungsten, growth of boron-doped diamond was observed. Further, when a tungsten substrate having a surface roughness of 0.5 μm or less was used, the peelability between the boron-doped diamond and the substrate was good.
Moreover, there was no difference in the growth of boron-doped diamond and the releasability between the case where the substrate was subjected to oxygen plasma treatment and the case where the substrate was not treated. From this, for example, in order to remove boron-doped diamond from the substrate, it is possible to reuse the substrate even if the substrate is oxidized along with oxidation treatment such as heat treatment or oxygen plasma irradiation. I was able to confirm.

Basically, boron-doped diamond was produced in the same manner as in Example 1. However, in the present Example 2, the following were used as a board | substrate.
A substrate obtained by forming a tungsten layer on a surface of a polygonal pyramid (pyramid type) carbon material with a mirror finish using a high frequency magnetron sputtering apparatus was used. The conditions for forming the tungsten layer were as follows.

Target: Purity 99.9999%
Atmosphere: Argon gas Vacuum degree: 0.6 Pa
Output: 70W
Deposition time: 1 hour Tungsten layer thickness: 5 μm
In this substrate, the surface on which the boron-doped diamond is grown is inclined with respect to the horizontal plane. When this substrate was used to synthesize boron-doped diamond in the same manner as in Example 1, the boron-doped diamond grew well during the CVD synthesis, and the substrate was naturally cooled after the CVD synthesis was completed. The diamond layer completely peeled from the substrate, and flowed down from the substrate along the inclination of the polygonal pyramid, and could be recovered at the lower end of the substrate.

  Therefore, every time the growth process of boron-doped diamond is completed, the process of opening the CVD chamber and removing the boron-doped diamond from the substrate becomes unnecessary, and the boron-doped diamond can be continuously synthesized. As a result, the productivity of boron-doped diamond is improved.

  Basically, boron-doped diamond was produced in the same manner as in Example 1. However, in Example 3, a sintered body of tungsten and titanium was used as the substrate. The substrate made of this sintered body was manufactured as follows.

  After mixing tungsten powder and carbon powder, carbonization and pulverization were performed to obtain tungsten carbide. Titanium carbide was mixed with this, granulated, pressed, then sintered, and the shaped one was wrapped to obtain a substrate made of a sintered body.

  The surface of this substrate was evaluated using a scanning electron microscope and an energy dispersive X-ray analyzer (SEM-EDX). FIG. 1 is an EDX mapping diagram of the substrate surface before the boron-doped diamond film is formed. It was confirmed that the tungsten region (region that appears white in FIG. 1) having a size of about 10 μm to 20 μm is dispersed in the titanium region (region that appears black in FIG. 1).

  Using the substrate described above and growing boron-doped diamond for 2 hours in the same manner as in Example 1, no change was seen even when the substrate in the chamber was viewed after completion, and boron-doped diamond was formed on the substrate. There was no diamond film. However, it was confirmed that many boron-doped diamond particles were scattered around the substrate. As shown in FIG. 2B, the boron-doped diamond 203 is formed only in the tungsten region of the substrate 201, and the substrate 201 is naturally cooled after the CVD synthesis. This is probably because 203 was peeled off from the substrate 201 and scattered. Therefore, according to the method described above, a boron-doped diamond powder can be obtained without performing a pulverization step.

  Further, when boron-doped diamond was grown for 10 hours using the above-described substrate in the same manner as in Example 1, a completely detached free-standing diamond thin film could be recovered after the completion of CVD. Presumably, when the growth time is long, the boron-doped diamond formed in the tungsten region also grows in the horizontal direction to form a film and is finally recovered as a free-standing diamond thin film.

(1) Production of Conductive Diamond Particles The boron-doped diamond flakes obtained in Examples 1 to 3 were pulverized in a menor mortar for 3 hours to produce boron-doped diamond particles (conductive diamond particles). Since the thickness of the boron-doped diamond flakes is about several μm to several tens of μm, pulverization was easy. For the pulverization, a pulverizer such as a planetary ball mill may be used.
(2) Evaluation of conductive diamond particles (Part 1)
Observation of the morphology of conductive diamond particles (hereinafter referred to as conductive diamond particles α) obtained by pulverizing boron-doped diamond having a thickness of 10 μm manufactured under the conditions of Example 1 with a scanning electron microscope did. FIG. 3 is a scanning electron micrograph showing the morphology of the conductive diamond particles α. The particle diameter of the conductive diamond particles α was at most 30 μm × 30 μm × 10 μm, and the particle diameters were uniform. Thus, it was found that the conductive diamond particles α produced in this example were finely divided and had a uniform particle size.

Further, as a reference, the form of particles (hereinafter referred to as diamond particles β) obtained by similarly pulverizing a diamond plate having a thickness of 0.8 mm using a menor mortar was observed with a scanning electron microscope. FIG. 4 is a scanning electron micrograph showing the morphology of the conductive diamond particles β. As a result, it was confirmed that the diamond particles β had a particle mass of 0.3 mm in size and had various particle sizes.
(3) Evaluation of conductive diamond particles (2)
The electrical resistivity of the conductive diamond particles α and diamond particles β was measured using a measuring jig as shown in FIG. The measurement method was as follows.

  Diamond particles are filled in a gap 3 of 3 mmφ × 2 mm at the center of the jig 1 and pressed between the upper and lower SUS plates 5 and 7 to be pressed and hardened. The compressed gap 3 is again filled with additional diamond particles and pressed at 20 MPa. Finally, the compressed gap 3 is filled with diamond particles and pressed at 30 MPa, and the electrical resistance between the upper and lower SUS plates 5 and 7 is measured with a tester. Note that the SUS plates 5 and 7 are separated by an insulating material 9 except for portions filled with diamond particles.

The electrical resistance measured in this way was 4.5 kΩ for the conductive diamond particles α and 60 kΩ for the diamond particles β. That is, the conductive diamond particles α showed good conductivity.
(4) Production of electrode An electrode was produced using conductive diamond particles α. The electrode was manufactured as follows.

  A 20% Nafion stock solution (manufactured by Aldrich) was diluted to 0.1% with purified water to prepare a 0.1% Nafion solution. 8 mg of conductive diamond particles α were mixed with 1.2 mL of this 0.1% Nafion solution, and then sufficiently stirred by ultrasonic waves to prepare a particle suspension.

  Glassy carbon having a size of 10 mm × 10 mm was mirror-polished, and the surface was hydrophilized by oxygen plasma treatment. The oxygen plasma treatment may be performed under conditions sufficient for introducing oxygen atoms and making them hydrophilic, for example, without roughening the glassy carbon surface. For example, it may be performed for about 1 minute at an output of 70 W. .

80 μL of the above-described particle suspension was applied to glassy carbon whose surface was hydrophilized, dried at room temperature overnight, and then heat-treated at 80 ° C. for 1 hour to dry the electrode α.
In addition, instead of the conductive diamond particles α, the same amount of diamond particles β was used to produce an electrode β by the same method as described above.

Moreover, instead of the conductive diamond particles α, the same amount of carbon black (manufactured by Holbein Kogyo) was used, and an electrode γ was manufactured by the same method as described above.
(5) Evaluation of electrodes The electrodes α, β, and γ were incorporated into a normal tripolar glass cell, and each was tested for electrochemical characteristics. The test was conducted by cyclic voltammetry, and the response to the iron cyano complex was examined. Using a test solution in which the concentration of the redox species was 1 mM and dissolved in 0.1 M potassium chloride, the scanning speed was set to 100 mV / s, and the measurement was performed. The current density was converted by the effective surface area relative to the surface area of each carbon particle calculated by the BET specific surface area.

  The measurement result regarding the electrode α is shown by a solid line in FIG. 6, and the result of 0.1 M potassium chloride as a blank solution is shown by a broken line. Electrode α showed a low residual current and an electrochemical response to the iron cyano complex was observed. In addition, peaks corresponding to oxidation and reduction of the iron cyano complex were observed sharply and clearly, and it was found that the electrode α had excellent electrochemical characteristics.

  The measurement result regarding the electrode β is shown by a solid line in FIG. 7, and the result of 0.1 M potassium chloride as a blank solution is shown by a broken line. As is apparent from the results of the electrical resistivity, the electrode β had a small contact area between the particles and exhibited a high electrical resistance. Therefore, it turned out that the response with respect to an iron cyano complex is slow, and the characteristic as an electrode is also inferior.

  The measurement result regarding the electrode γ is shown by a solid line in FIG. 8, and the result of 0.1 M potassium chloride which is a blank solution is shown by a broken line. The electrode β had a large residual current, and no reaction of the iron cyano complex was observed.

(1) Production of Fuel Cell Electrode Fuel cell electrode α2 was produced using conductive diamond particles α. The fuel cell electrode α2 can be used for a polymer solid oxide fuel cell (PEFC).

  The fuel cell electrode α2 was manufactured as follows. First, 30 mg of conductive diamond particles α are dispersed in 1.93 mL of a chloroplatinic acid aqueous solution whose concentration is adjusted to 50 mM, 0.2 mg of sodium borohydride is added thereto, and the mixture is stirred for 12 hours to reduce platinum. And immobilized on the surface of the conductive diamond particles α. As a result, a platinum-carrying diamond powder in which platinum as a noble metal catalyst was carried on the conductive diamond particles α was produced.

  Next, a 20% Nafion stock solution (manufactured by Aldrich) was diluted to 0.1% with purified water to prepare a 0.1% Nafion solution. After mixing 8 mg of the previously prepared platinum-supported diamond powder with 1.2 mL of this 0.1% Nafion solution, the mixture was sufficiently stirred by ultrasonic to prepare a particle suspension.

  Glassy carbon having a size of 10 mm × 10 mm was mirror-polished, and the surface was hydrophilized by oxygen plasma treatment. The oxygen plasma treatment may be performed under conditions sufficient for introducing oxygen atoms and making them hydrophilic, for example, without roughening the glassy carbon surface. For example, it may be performed for about 1 minute at an output of 70 W. .

  Applying 80 μL of the above-mentioned particle suspension to glassy carbon whose surface is hydrophilized, drying at room temperature overnight, and then heat-treating at 80 ° C. for 1 hour to complete the fuel cell electrode α2. did.

In addition, the same amount of diamond particles β was used instead of the conductive diamond particles α, and a fuel cell electrode β2 was produced by the same method as described above.
In addition, the same amount of carbon black (manufactured by Holbein Kogyo) was used in place of the conductive diamond particles α, and a fuel cell electrode γ2 was produced in the same manner as described above.
(2) Evaluation of Fuel Cell Electrode The following evaluation was performed on the assumption of a direct methanol fuel cell (DMFC) in which methanol can be directly supplied to the cell and reacted without being reformed into hydrogen.

  The fuel cell electrodes α2, β2, and γ2 were incorporated into a normal tripolar glass cell, and the electrochemical characteristics were tested. The current density was calculated from the hydrogen adsorption / desorption peak area when the produced fuel cell electrode was electrochemically measured in sulfuric acid, and expressed per unit area of platinum.

  FIG. 9 is a cyclic voltammogram measured using a test solution adjusted with 0.5M sulfuric acid so that the methanol concentration becomes 1M. In FIG. 9, the thick solid line is the measurement result of the fuel cell electrode α2, the thick broken line is the measurement result of the fuel cell electrode β2, and the thin solid line is the measurement result of the fuel cell electrode γ2.

  When the measurement results of the fuel cell electrode α2 and the measurement results of the fuel cell electrode γ2 are compared, the reaction currents seem to be almost the same, but if the fuel cell electrode γ2 has a large residual current, The reaction current of the fuel cell electrode α2 is larger.

  Further, when the fuel cell electrode α2 was used, an excellent result was obtained that the oxidation potential with respect to methanol could be suppressed to 80 mV. This means that a large electromotive force is generated as a fuel cell.

In addition, when the fuel cell electrode β2 was used, the reaction current with respect to methanol was small.
From the above, since the fuel cell electrode α2 is made of diamond as a carrier, there is no concern about the corrosion of the carrier, and it is suitable for a catalyst-carrying electrode because it has corrosion resistance and a small residual current. It was proved to be suitable for

  Needless to say, the present invention is not limited to the above-described embodiments, and can be implemented in various modes without departing from the scope of the present invention.

It is an EDX mapping figure of the substrate surface which consists of a sintered compact of tungsten and titanium before forming a boron dope diamond film. It is explanatory drawing showing the method of manufacturing the powder of boron dope diamond, (a) is a case where the board | substrate consisting only of tungsten is used, (b) uses the board | substrate consisting of the sintered compact of tungsten and titanium. Is the case. 3 is a scanning electron micrograph showing the form of conductive diamond particles α. 3 is a scanning electron micrograph showing the form of conductive diamond particles β. It is explanatory drawing showing the structure of the measuring jig used in order to measure an electrical resistivity. It is a graph showing the measurement result of the electrochemical characteristic regarding the electrode (alpha). It is a graph showing the measurement result of the electrochemical characteristic regarding the electrode (beta). It is a graph showing the measurement result of the electrochemical characteristic regarding electrode (gamma). 4 is a cyclic voltammogram for fuel cell electrodes α2, β2, and γ2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Jig, 3 ... Gap, 5, 7 ... SUS board, 9 ... Insulating material,
101, 201 ... substrate, 103, 203 ... boron-doped diamond,
105 ... powder

Claims (6)

  A method for producing boron-doped diamond, characterized in that, using a CVD method, boron-doped diamond is grown on a substrate on which tungsten or an oxide thereof is exposed at least at a part of the surface.   2. The method for producing boron-doped diamond according to claim 1, wherein the surface roughness of the substrate is 0.5 [mu] m or less.   3. The method for producing boron-doped diamond according to claim 1, wherein a region made of tungsten or an oxide thereof and a region not containing tungsten are mixed on the surface of the substrate. After the boron-doped diamond is grown on the substrate, the cooling step of lowering the temperature of the boron-doped diamond and the substrate than that during the growth,
The surface of the substrate on which the boron-doped diamond is grown is inclined with respect to a horizontal direction during the cooling step or after the cooling step. A method for producing boron-doped diamond.   The boron dope diamond manufactured with the manufacturing method of the boron dope diamond in any one of Claims 1-4.   The electrode which carry | supported the powder which consists of boron dope diamonds of Claim 5 on the surface of the base material which consists of an electroconductive substance.