CN112892411A - Method for growing large-particle diamond at high temperature and high pressure - Google Patents

Method for growing large-particle diamond at high temperature and high pressure Download PDF

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CN112892411A
CN112892411A CN202110100312.XA CN202110100312A CN112892411A CN 112892411 A CN112892411 A CN 112892411A CN 202110100312 A CN202110100312 A CN 202110100312A CN 112892411 A CN112892411 A CN 112892411A
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diamond
pressure
temperature
growth
catalyst
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CN112892411B (en
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贺端威
田毅
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Guangdong Zhengxin Hard Material Technology Research And Development Co ltd
Sichuan University
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Guangdong Zhengxin Hard Material Technology Research And Development Co ltd
Sichuan University
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J3/00—Processes of utilising sub-atmospheric or super-atmospheric pressure to effect chemical or physical change of matter; Apparatus therefor
    • B01J3/06—Processes using ultra-high pressure, e.g. for the formation of diamonds; Apparatus therefor, e.g. moulds or dies
    • B01J3/065—Presses for the formation of diamonds or boronitrides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J3/00—Processes of utilising sub-atmospheric or super-atmospheric pressure to effect chemical or physical change of matter; Apparatus therefor
    • B01J3/06—Processes using ultra-high pressure, e.g. for the formation of diamonds; Apparatus therefor, e.g. moulds or dies
    • B01J3/062—Processes using ultra-high pressure, e.g. for the formation of diamonds; Apparatus therefor, e.g. moulds or dies characterised by the composition of the materials to be processed
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B1/00—Single-crystal growth directly from the solid state
    • C30B1/12—Single-crystal growth directly from the solid state by pressure treatment during the growth
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/02—Elements
    • C30B29/04—Diamond

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  • Crystallography & Structural Chemistry (AREA)
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Abstract

The invention provides a method for growing large-particle diamond at high temperature and high pressure, which takes seed crystals, a catalyst and a carbon source as raw materials and comprises the following process steps: (1) putting the crystal seeds in a catalyst for compression molding to obtain a catalyst-coated crystal seed complex, and then coating the complex with a carbon source to form a diamond growth blank; (2) combining the diamond growth blank obtained in the step (1) with a high-temperature high-pressure device matched with static high-pressure equipment to form a synthetic block, then putting the synthetic block into the static high-pressure equipment, firstly pressurizing to the diamond growth pressure, then heating to the diamond growth temperature, maintaining the pressure and preserving the heat for growth; (3) and after the pressure maintaining and heat preservation are finished, firstly cooling to room temperature, then reducing the pressure to normal pressure, then returning the static high-pressure equipment, taking out the block body of the diamond coated by the residual carbon source and the catalyst, and removing the residual carbon source and the catalyst of the block body to obtain the diamond. The method can provide carbon sources for diamond growth from multiple directions, and improve the growth rate of the diamond and the yield of large diamond single crystals.

Description

Method for growing large-particle diamond at high temperature and high pressure
Technical Field
The invention belongs to the technical field of artificial diamond, and relates to a method for growing large-particle diamond at high temperature and high pressure.
Background
The diamond has physical properties of high hardness, high thermal conductivity, low expansion coefficient and the like, and is applied to a plurality of fields of mechanical processing, oil drilling, electronic devices, national defense and military industry, medical appliances, jewelry and the like. The performance of the artificial diamond single crystal can be compared with that of natural diamond, and the doped diamond has certain physical performance even far exceeding that of the natural diamond.
Regarding the synthesis of large-particle artificial diamond, a temperature gradient method is currently generally adopted, which utilizes a catalyst to convert a carbon source into diamond crystals at high temperature and high pressure. According to the temperature gradient method, the position relation of a carbon source, a catalyst and a seed crystal is shown in figure 1, and a proper temperature difference Delta T must be formed between the carbon source and the seed crystal, and the temperature difference provides a driving force for diamond growth. Therefore, the temperature gradient method has the following problems: (1) as can be seen from the position relationship of the carbon source, the catalyst and the seed crystal, in the growth process of the diamond, the carbon source can only transmit carbon atoms in one direction through the catalyst, so that the transmission efficiency of carbon is low, the growth rate of the diamond is influenced, and the growth time and the growth cost of the diamond crystal are increased; (2) because a proper temperature difference delta T must exist between the carbon source and the seed crystal, the assembly design of the carbon source, the catalyst and the seed crystal is limited, and the assembly difficulty is high; (3) because the seed crystal has different crystal faces, and the growth speeds of the different crystal faces are different under the condition of the same temperature and pressure, for example, the crystal faces (111) and (100) are superior to those of other crystal faces, the crystal face with the growth advantage of the seed crystal perpendicular to the carbon source transmission direction needs to be considered when the diamond single crystal is grown by the temperature gradient method, and the crystal faces are difficult to distinguish when the size of the seed crystal is small, so that the assembly difficulty of the carbon source, the catalyst and the seed crystal is further improved, and the yield of the large diamond single crystal is reduced.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a method for growing large-particle diamond under high temperature and high pressure so as to provide a carbon source for diamond growth from multiple directions, improve the growth rate of diamond and the yield of large diamond single crystal and reduce the assembly difficulty of the carbon source, a catalyst and a seed crystal.
The technical idea of the invention is as follows: the method mainly aims at improving the position relation among the seed crystal, the catalyst and the carbon source in the temperature gradient method to form the position relation that the seed crystal is completely wrapped by the catalyst and the catalyst is completely wrapped by the carbon source, so that the carbon source is provided for the growth of the diamond from multiple directions, each crystal face of the diamond seed crystal can receive the carbon source to carry out all-around growth, and the assembly difficulty of the carbon source, the catalyst and the seed crystal is reduced.
The method for growing the large-particle diamond at high temperature and high pressure takes seed crystals, a catalyst and a carbon source as raw materials, and comprises the following process steps:
(1) placing the seed crystal in a catalyst for compression molding to obtain a catalyst-coated seed crystal complex, and then coating the complex with a carbon source to form a diamond growth blank, wherein the external shape and size of the diamond growth blank are matched with those of an inner cavity of a high-temperature and high-pressure device matched with static and high-pressure equipment;
(2) combining the diamond growth blank obtained in the step (1) with a high-temperature high-pressure device matched with static high-pressure equipment to form a synthetic block, then putting the synthetic block into the static high-pressure equipment, firstly pressurizing to the diamond growth pressure, then heating to the diamond growth temperature, maintaining the pressure and preserving the heat for growth;
(3) and after the pressure maintaining and heat preservation are finished, firstly cooling to room temperature, then reducing the pressure to normal pressure, then returning the static high-pressure equipment, taking out the block body of the diamond coated by the residual carbon source and the catalyst, and removing the residual carbon source and the catalyst of the block body to obtain the diamond. Washing the obtained diamond crystal with deionized water to remove residual HNO3Drying at 50-60 deg.C to remove water on the surface, and storing.
In the method for growing the large-particle diamond at high temperature and high pressure, the carbon source is used for wrapping the composite body in the step (1) in the following two ways:
one is that the composite body is put into a carbon source to be pressed into a diamond growth blank; and the other method is to press a carbon source into an inclusion, wherein the shape and the size of an inner cavity of the inclusion are matched with the external shape and the size of the complex, the external shape and the size of the inclusion are matched with the shape and the size of an inner cavity of a high-temperature and high-pressure device matched with static and high-pressure equipment, and the complex and the inclusion are combined to form the diamond growth blank. For example, the inner cavity of the high-temperature and high-pressure device matched with the static and high-pressure equipment is cylindrical, the inclusion is composed of a circular tube formed by pressing a carbon source and two wafers, the outer diameter and the length of the circular tube are matched with the diameter and the length of the inner cavity of the high-temperature and high-pressure device matched with the static and high-pressure equipment, the shape of the complex is preferably cylindrical, the inner diameter of the circular tube is matched with the outer diameter of the complex, the diameter of the wafers is the same as the inner diameter of the circular tube, the sum of the thicknesses of the two wafers and the length of the cylindrical complex is equal to the length of the circular tube, the complex is put into. For example, the inner cavity of the high-temperature and high-pressure device matched with the static high-pressure equipment is spherical, the inclusion is composed of two identical semi-hollow spherical shells formed by pressing a carbon source, the outer spherical diameter of each semi-hollow spherical shell is matched with the spherical diameter of the inner cavity of the high-temperature and high-pressure device matched with the static high-pressure equipment, the shape of the composite body is preferably spherical, the inner spherical diameter of each semi-hollow spherical shell is matched with the spherical diameter of the composite body, and the composite body is wrapped by the two semi-hollow spherical shells to form a diamond growth blank.
In the method for growing the large-particle diamond at high temperature and high pressure, the number of the seed crystals is one or more, the number of the seed crystals is selected according to the comprehensive consideration of the static high-pressure equipment and the particle size required by the synthesized diamond, under the condition that the cavity space of the static high-pressure equipment is limited, if the number of the seed crystals is too large, the growth efficiency and the size of the crystal are influenced due to the simultaneous growth and the mutual competition of the seed crystals, and when the number of the seed crystals is more, the seed crystals are spaced correspondingly according to the particle size required by the synthesized diamond; the amount of the catalyst can completely wrap the seed crystal and meet the growth space of the seed crystal; the amount of carbon source is such that it completely encapsulates the composite and meets the requirements of the desired growth size of the diamond.
The catalyst requirement of the method for growing the large-particle diamond at high temperature and high pressure Is the same as that of the temperature gradient method, and the catalyst can be transition metal simple substances such as Fe, Ni, Co, Ru, Rh, Pd, Os, Is or Pt;other simple metals such as Mo, Ti, Zr, Cu, Zn or Ge; elemental non-metals, such as P or Se; alloys containing a transition metal as a main component, such as manganese-nickel alloy, iron-cobalt alloy, or iron-nickel-cobalt alloy; carbonates, e.g. Li2CO3、Na2CO3、K2CO3、Cs2CO3、Li2CO3Or MgCO3(ii) a Sulfates, e.g. MgSO4Or Na2SO4(ii) a Non-metallic salts, e.g. NH4Cl、NH4Br、NH4I or (NH)4)2HPO4。
The method for growing the large-particle diamond at high temperature and high pressure has the same carbon source requirement as that of the temperature gradient method, and can be a carbonaceous material and a carbonaceous material, wherein the carbonaceous material comprises diamond, graphite and C60Carbon-containing materials include organic materials or inorganic materials containing carbon atoms.
According to the method for growing the large-particle diamond at the high temperature and the high pressure, in the step (2), the growth pressure P of the diamond is 4GPa < P <15GPa, and the growth temperature T of the diamond is 1000 ℃ < T <3000 ℃; the pressure rise rate during pressurization is not more than 60GPa/h, and the temperature rise rate during temperature rise is 0.1-400 ℃/min. The main factors influencing the growth temperature and growth pressure of diamond are the catalysts used, which can be determined by reference to the temperature gradient method and by experiments.
In the method for growing the large-particle diamond at high temperature and high pressure, in the step (3), the cooling rate during cooling is not more than 6000 ℃/min, and the pressure reduction rate during pressure reduction is not more than 120 GPa/h.
According to the method for growing the large-particle diamond at the high temperature and the high pressure, in the step (3), the residual carbon source is removed by adopting a knocking, fracturing or crushing method, and the catalyst is removed by adopting an acid treatment method, wherein the acid treatment method is to put the block body without the residual carbon source into acid liquor and soak the block body at the temperature of 5-200 ℃ until the catalyst is completely separated from the diamond. The acid solution is one of a nitric acid solution, a hydrofluoric acid solution, a hydrochloric acid solution and a sulfuric acid solution, or consists of at least two of the nitric acid solution, the hydrofluoric acid solution, the hydrochloric acid solution and the sulfuric acid solution.
Compared with the prior art, the invention has the following beneficial effects:
(1) the method of the invention places the crystal seeds in the catalyst for compression molding to obtain the catalyst-coated crystal seed complex, then coats the complex with the carbon source to form the diamond growth blank, and the position relation of the crystal seeds, the catalyst and the carbon source provides a new technical scheme for growing large-particle diamond at high temperature and high pressure.
(2) According to the method, the crystal seeds are completely wrapped by the catalyst, and the catalyst is completely wrapped by the carbon source, so that carbon atoms are simultaneously dissolved into the catalyst from different directions in a temperature and pressure region for diamond growth and are transmitted in the catalyst, and the carbon atoms in the catalyst come from multiple directions, so that the carbon atoms can quickly reach a saturated state in the catalyst, the growth of diamond crystals can be quickly started, the growth rate of the diamond is effectively improved, and the growth cost is reduced.
(3) According to the method, the diamond seed crystal is completely immersed in the catalyst, and each crystal face of the diamond can receive carbon atoms transmitted by the catalyst, so that the diamond seed crystal can grow in all directions simultaneously, and the yield of large diamond single crystals is improved.
(4) The method of the invention has no requirement on the temperature difference between the carbon source and the seed crystal, only the seed crystal is completely wrapped by the catalyst and the catalyst is completely wrapped by the carbon source during assembly, and the diamond growth blank formed after wrapping can be positioned in the temperature and pressure area for diamond growth in a high-temperature and high-pressure device matched with static and high-pressure equipment, so the assembly design is flexible, the difficulty in assembly is greatly reduced, and the method is convenient to master and control.
(5) The method is suitable for synthesizing the large-particle monocrystalline diamond and the large-particle polycrystalline diamond, and the used equipment is conventional equipment and is easy to assemble, so that the method is favorable for implementation and popularization.
Drawings
FIG. 1 is a schematic diagram showing the positional relationship among a carbon source, a catalyst, and a seed crystal in a conventional temperature gradient method;
FIG. 2 is a schematic diagram of the position relationship of a carbon source, a catalyst and a seed crystal when the seed crystal is one in the method of the present invention, and a synthetic block formed by combining a diamond growth blank formed by the carbon source, the catalyst and the seed crystal with a high temperature and high pressure device matched with static and high pressure equipment;
FIG. 3 is a schematic diagram of a synthetic block formed by combining a carbon source, a catalyst and seed crystals, and a diamond growth blank formed by the carbon source, the catalyst and the seed crystals, and a high-temperature and high-pressure device matched with static and high-pressure equipment when the seed crystals are two in the method of the invention;
FIG. 4 is a Scanning Electron Microscope (SEM) image of a diamond crystal synthesized in example 1 of the present invention;
FIG. 5 is a Scanning Electron Microscope (SEM) image of a diamond crystal synthesized in example 2 of the present invention;
FIG. 6 is a Scanning Electron Microscope (SEM) image of a diamond crystal synthesized in example 3 of the present invention;
FIG. 7 is a Scanning Electron Microscope (SEM) image of a diamond crystal synthesized in example 4 of the present invention;
FIG. 8 is a Scanning Electron Microscope (SEM) image of a diamond crystal synthesized in example 5 of the present invention;
FIG. 9 is a Scanning Electron Microscope (SEM) image of a diamond crystal synthesized in example 6 of the present invention;
FIG. 10 is a Scanning Electron Microscope (SEM) image of a diamond crystal synthesized in example 7 of the present invention;
in the figure, 1-carbon source, 2-catalyst, 3-crystal seed, 4-insulating layer, 5-heating layer, 6-insulating layer, 7-pyrophyllite layer, 8-graphite rod, 9-conductive metal block.
Detailed Description
The method for growing large-grain diamond under high temperature and high pressure according to the present invention will be further described by way of examples with reference to the accompanying drawings. It is to be understood that the described embodiments are merely a few embodiments of the invention and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the following embodiments, the static high-pressure equipment is a domestic hinge type cubic press with a model of DS 6 × 8MN, and the manufacturing enterprise: zhang Jiakou prospecting mechanical plant; the high-temperature and high-pressure device matched with the hinge type cubic press is shown in fig. 2 and fig. 3, and comprises a main body structure consisting of an insulating layer 4, a heating layer 5, a heat preservation layer 6 and a pyrophyllite layer 7, a graphite rod 8 and two conductive metal blocks 9, wherein the two graphite rods 8 are in contact with the heating layer 5 through holes respectively penetrating through the top and the bottom of the heat preservation layer 6, the two conductive metal blocks 9 are in contact with the graphite rod through holes respectively penetrating through the top and the bottom of the pyrophyllite layer 7, an inner cavity formed by the surrounding of the insulating layer 4 is cylindrical, the diameter D is 10mm, and the length L is 9.6 mm. The catalyst, carbon source and seed crystal are purchased from the market.
Example 1
In the embodiment, the seed crystal is a single crystal diamond, is yellow and has an irregular shape, and the particle size is 50 microns and is 1 particle; the carbon source is graphite powder, the average particle size is 1-2 mu m, the purity is 99.99 percent, and the weight is 1 g; the catalyst is cobalt powder with purity of 99.9%, average particle size of 1-2 μm, and weight of 0.8 g.
The steps of growing the large-particle diamond under high temperature and high pressure are as follows:
(1) placing the crystal seed 3 in the catalyst cobalt powder 2, and performing compression molding to obtain a cylindrical complex (with the diameter of 6mm and the length of 3.2mm) with the catalyst coated with the crystal seed; pressing carbon source graphite powder 3 into an inclusion body consisting of a round pipe and two wafers, wherein the inner diameter of the round pipe is 6mm, the outer diameter of the round pipe is 10mm, the length of the round pipe is 7.2mm, the round pipe is matched with an inner cavity of a high-temperature and high-pressure device matched with a hinge type cubic press, the diameter of the wafer is the same as the inner diameter of the round pipe, the thickness of the wafer is 2mm, the cylindrical complex is filled into the round pipe pressed by the graphite powder, and two ends of the round pipe are sealed by the wafer to form a diamond growth blank body with the outer diameter of 10mm and the length of;
(2) combining the diamond growth blank obtained in the step (1) with a high-temperature high-pressure device matched with a hinge type cubic press to form a synthetic block shown in fig. 2, putting the synthetic block into the hinge type cubic press, pressurizing to 5GPa at the boosting rate of 8GPa/h, heating to 1300 ℃ at the heating rate of 100 ℃/min, and maintaining the pressure and the temperature for 3h under the pressure and the temperature to perform diamond growth;
(3) after the pressure maintaining and heat preservation are finished, the temperature is reduced to the room temperature at the cooling rate of 300 ℃/min, and then the pressure reduction rate of 10GPa/h is carried outReducing the pressure to normal pressure, returning the hinge type cubic press, taking out the block body of the diamond coated by the residual carbon source graphite and the catalyst cobalt, knocking the block body to remove the residual graphite on the surface layer, and putting the rod body of the diamond coated by the cobalt into HNO with the mass concentration of 20%3Heating the solution to boiling to remove cobalt to obtain diamond crystals, and cleaning the diamond crystals with deionized water to remove residual HNO3Drying at 50 deg.C to remove water on the surface, and storing.
The diamond synthesized in this example was single crystal diamond having a grain size of about 380 μm, and its SEM image is shown in fig. 4.
Example 2
In the embodiment, the seed crystal is a single crystal diamond, is yellow and has an irregular shape, and the particle size is 500 microns and is 1 particle; the carbon source is graphite powder, the average particle size is 1-2 mu m, the purity is 99.99 percent, and the weight is 1 g; the catalyst is cobalt powder with purity of 99.5%, average particle size of 1-2 μm, and weight of 1.2 g.
The steps of growing the large-particle diamond under high temperature and high pressure are as follows:
(1) placing the crystal seed 3 in the catalyst cobalt powder 2, and performing compression molding to obtain a cylindrical complex (with the diameter of 6mm and the length of 4mm) with the catalyst coated with the crystal seed; pressing carbon source graphite powder 3 into an inclusion body consisting of a round pipe and two wafers, wherein the inner diameter of the round pipe is 6mm, the outer diameter of the round pipe is 10mm, the length of the round pipe is 7.2mm, the round pipe is matched with an inner cavity of a high-temperature and high-pressure device matched with a hinge type cubic press, the diameter of the wafer is the same as the inner diameter of the round pipe, the thickness of the wafer is 1.6mm, the cylindrical complex is filled into the round pipe pressed by the graphite powder, and the two ends of the round pipe are sealed by the wafers to form a diamond growth blank body with the outer diameter of 10mm and the;
(2) combining the diamond growth blank obtained in the step (1) with a high-temperature high-pressure device matched with a hinge type cubic press to form a synthetic block shown in the figure 2; putting the synthetic block into a hinge type cubic press, pressurizing to 5GPa at the pressure increasing rate of 8GPa/h, heating to 1300 ℃ at the temperature increasing rate of 80 ℃/min, and maintaining the pressure and the temperature for 4h under the pressure and the temperature to grow the diamond;
(3) after the pressure maintaining and heat preservation are finished, the temperature is reduced at the cooling rate of 10 ℃/minCooling to room temperature, reducing the pressure to normal pressure at the pressure reduction rate of 10GPa/h, returning the hinge type cubic press, taking out the block body of the diamond coated by the residual carbon source graphite and the catalyst cobalt, knocking the block body to remove the residual graphite on the surface layer, and putting the rod body of the diamond coated by the cobalt into HNO with the mass concentration of 20%3Heating the solution to boiling to remove cobalt to obtain diamond crystals, and cleaning the diamond crystals with deionized water to remove residual HNO3Drying at 60 deg.C to remove water on the surface, and storing.
The diamond synthesized in this example was single crystal diamond having a grain size of about 2068 μm, and its SEM image is shown in FIG. 5.
Example 3
In the embodiment, the seed crystal is a single crystal diamond, is yellow and has an irregular shape, and the particle size is 500 microns and is 1 particle; the carbon source is graphite powder, the average particle size is 1-2 mu m, the purity is 99.9%, and the weight is 1 g; the catalyst is iron powder with purity of 99.5%, average particle size of 1-2 μm, and weight of 1.2 g.
The steps of growing the large-particle diamond under high temperature and high pressure are as follows:
(1) placing the seed crystal 3 in the catalyst iron powder 2, and performing compression molding to obtain a cylindrical complex (with the diameter of 6mm and the length of 4.2mm) with the catalyst coated seed crystal; pressing carbon source graphite powder 3 into an inclusion body consisting of a round pipe and two wafers, wherein the inner diameter of the round pipe is 6mm, the outer diameter of the round pipe is 10mm, the length of the round pipe is 7.2mm, the round pipe is matched with an inner cavity of a high-temperature and high-pressure device matched with a hinge type cubic press, the diameter of the wafer is the same as the inner diameter of the round pipe, the thickness of the wafer is 1.5mm, the cylindrical complex is filled into the round pipe pressed by the graphite powder, and the two ends of the round pipe are sealed by the wafers to form a diamond growth blank body with the outer diameter of 10mm and the;
(2) combining the diamond growth blank obtained in the step (1) with a high-temperature high-pressure device matched with a hinge type cubic press to form a synthetic block shown in the figure 2; putting the synthetic block into a hinge type cubic press, pressurizing to 5GPa at the pressure increasing rate of 10GPa/h, heating to 1350 ℃ at the temperature increasing rate of 100 ℃/min, and maintaining the pressure and the temperature for 3h under the pressure and the temperature to grow the diamond;
(3) the pressure maintaining and the heat preservation are finishedThen, cooling to room temperature at a cooling rate of 20 ℃/min, then reducing the pressure to normal pressure at a pressure reduction rate of 10GPa/h, returning the hinge type cubic press, taking out the block body of diamond coated by residual carbon source graphite and catalyst iron, knocking the block body to remove residual graphite on the surface layer, and then putting the rod body of diamond coated by iron into HNO with the mass concentration of 25%3Heating the solution to boiling to remove iron to obtain diamond crystals, and cleaning the obtained diamond crystals with deionized water to remove residual HNO3Drying at 60 deg.C to remove water on the surface, and storing.
The diamond synthesized in this example was single crystal diamond having a grain size of about 1947 μm, and its SEM image is shown in fig. 6.
Example 4
In the embodiment, the seed crystal is a single crystal diamond, is yellow and has an irregular shape, and the particle size is 500 microns and is 1 particle; the carbon source is graphite powder, the average particle size is 1-2 mu m, the purity is 99.9%, and the weight is 1.2 g; the catalyst is Fe64Ni36 alloy powder with an average particle size of 40-50 μm and a weight of 1 g.
The steps of growing the large-particle diamond under high temperature and high pressure are as follows:
(1) placing the crystal seeds 3 in a catalyst Fe64Ni36 alloy powder 2, and performing compression molding to obtain a cylindrical complex (with the diameter of 6mm and the length of 4mm) of the catalyst coated crystal seeds; pressing carbon source graphite powder 3 into an inclusion body consisting of a round pipe and two wafers, wherein the inner diameter of the round pipe is 6mm, the outer diameter of the round pipe is 10mm, the length of the round pipe is 7.2mm, the round pipe is matched with an inner cavity of a high-temperature and high-pressure device matched with a hinge type cubic press, the diameter of the wafer is the same as the inner diameter of the round pipe, the thickness of the wafer is 1.6mm, the cylindrical complex is filled into the round pipe pressed by the graphite powder, and the two ends of the round pipe are sealed by the wafers to form a diamond growth blank body with the outer diameter of 10mm and the;
(2) combining the diamond growth blank obtained in the step (1) with a high-temperature high-pressure device matched with a hinge type cubic press to form a synthetic block shown in the figure 2; putting the synthetic block into a hinge type cubic press, pressurizing to 6GPa at the pressure increasing rate of 12GPa/h, heating to 1450 ℃ at the temperature increasing rate of 100 ℃/min, and maintaining the pressure and the temperature for 2.5h under the pressure and the temperature to grow the diamond;
(3) after the pressure maintaining and heat preservation are finished, the temperature is reduced to room temperature at the cooling rate of 30 ℃/min, then the pressure is reduced to normal pressure at the pressure reduction rate of 10GPa/h, then the hinge type cubic press is returned, the diamond block coated by the residual carbon source graphite and the catalyst Fe64Ni36 alloy is taken out, the residual graphite on the surface layer is removed by knocking the block, and then the diamond rod coated by the Fe64Ni36 alloy is placed into HNO with the mass concentration of 25 percent3Heating the solution to boiling to remove Fe64Ni36 alloy to obtain diamond crystal, and cleaning the diamond crystal with deionized water to remove residual HNO3Drying at 50 deg.C to remove water on the surface, and storing.
The diamond synthesized in this example was single crystal diamond having a grain size of about 1795 μm, and its SEM image is shown in fig. 7.
Example 5
In the embodiment, the seed crystal is a single crystal diamond, is yellow and has an irregular shape, and the particle size is 50 microns and is 1 particle; the carbon source is graphite powder, the average particle size is 1-2 mu m, the purity is 99.9%, and the weight is 0.8 g; the catalyst is selenium powder with average particle size of 60-70 μm, purity of 99.9%, and weight of 0.8 g.
The steps of growing the large-particle diamond under high temperature and high pressure are as follows:
(1) placing the seed crystal 3 in the catalyst selenium powder 2, and performing compression molding to obtain a cylindrical complex (with the diameter of 6mm and the length of 3mm) with the catalyst coated on the seed crystal; pressing carbon source graphite powder 3 into an inclusion body consisting of a round pipe and two wafers, wherein the inner diameter of the round pipe is 6mm, the outer diameter of the round pipe is 10mm, the length of the round pipe is 6mm, the round pipe is matched with an inner cavity of a high-temperature and high-pressure device matched with a hinge type cubic press, the diameter of the wafer is the same as the inner diameter of the round pipe, the thickness of the wafer is 1.5mm, the cylindrical complex is filled into the round pipe pressed by the graphite powder, and the two ends of the round pipe are sealed by the wafers to form a diamond growth blank body with the outer diameter of 10 mm;
(2) combining the diamond growth blank obtained in the step (1) with a high-temperature high-pressure device matched with a hinge type cubic press to form a synthetic block shown in the figure 2; putting the synthetic block into a hinge type cubic press, pressurizing to 8GPa at the pressure increasing rate of 10GPa/h, heating to 1600 ℃ at the temperature increasing rate of 100 ℃/min, and maintaining the pressure and the temperature for 6h under the pressure and the temperature to grow the diamond;
(3) after the pressure maintaining and heat preservation are finished, firstly cooling to room temperature at the cooling rate of 1 ℃/min, then reducing the pressure to normal pressure at the pressure reduction rate of 5GPa/h, then returning the hinge type cubic press, taking out the block body of the diamond coated by the residual carbon source graphite and the catalyst selenium, knocking the block body to remove the residual graphite on the surface layer, and then putting the rod body of the diamond coated by the selenium into HNO with the mass concentration of 65%3Heating the solution to boil to remove selenium to obtain diamond crystal, and cleaning the diamond crystal with deionized water to remove residual HNO3Drying at 60 deg.C to remove water on the surface, and storing.
The diamond synthesized in this example was single crystal diamond having a grain size of about 257 μm, and its SEM image is shown in fig. 8.
Example 6
In the embodiment, the seed crystal is a single crystal diamond, is yellow and has an irregular shape, and the particle size is 500 mu m and 2 particles; the carbon source is graphite powder, the average particle size is 1-2 mu m, the purity is 99.99%, and the weight is 1.5 g; the catalyst is cobalt powder with purity of 99.5%, average particle size of 1-2 μm, and weight of 1.6 g.
The steps of growing the large-particle diamond under high temperature and high pressure are as follows:
(1) placing the two crystal seeds 3 in the catalyst cobalt powder 2, and performing compression molding to obtain a catalyst-coated crystal seed cylindrical complex (with the diameter of 6mm and the length of 6.5mm), wherein the distance between the two crystal seeds is about 1 mm; pressing carbon source graphite powder 3 into an inclusion body consisting of a round pipe and two wafers, wherein the inner diameter of the round pipe is 6mm, the outer diameter of the round pipe is 10mm, the length of the round pipe is 8.5mm, the round pipe is matched with an inner cavity of a high-temperature and high-pressure device matched with a hinge type cubic press, the diameter of the wafer is the same as the inner diameter of the round pipe, the thickness of the wafer is 1mm, the cylindrical complex is filled into the round pipe pressed by the graphite powder, and two ends of the round pipe are sealed by the wafer to form a diamond growth blank body with the outer diameter of 10mm and the length;
(2) combining the diamond growth blank obtained in the step (1) with a high-temperature high-pressure device matched with a hinge type cubic press to form a synthetic block shown in the figure 3; putting the synthetic block into a hinge type cubic press, pressurizing to 5GPa at the pressure increasing rate of 10GPa/h, heating to 1300 ℃ at the temperature increasing rate of 100 ℃/min, and maintaining the pressure and the temperature for 6h under the pressure and the temperature to grow the diamond;
(3) after the pressure maintaining and heat preservation are finished, firstly cooling to room temperature at a cooling rate of 5 ℃/min, then reducing the pressure to normal pressure at a pressure reduction rate of 10GPa/h, then returning the static high-pressure equipment, taking out the block body of the diamond coated by the residual carbon source graphite and the catalyst cobalt, knocking the block body to remove the residual graphite on the surface layer, and then putting the rod body of the diamond coated by the cobalt into HNO with the mass concentration of 30 percent3Heating the solution to boiling to remove cobalt to obtain two diamond crystals, and cleaning the obtained diamond crystals with deionized water to remove residual HNO3Drying at 50 deg.C to remove water on the surface, and storing.
The diamond synthesized in this example was a single crystal diamond, and its SEM image is shown in FIG. 9, in which (a) of FIG. 9 shows a diamond grain size of about 1662 μm, and (b) of FIG. 9 shows a diamond grain size of about 1970 μm.
Example 7
In the embodiment, the seed crystal is a single crystal diamond, is yellow and has an irregular shape, and the particle size is 10 microns and is 1 particle; the carbon source is diamond powder with the granularity of 50 mu m and the purity of 99.9 percent, and the weight is 1.4 g; the catalyst is cobalt powder with an average particle size of 1-2 μm, a purity of 99.9%, and a weight of 1.2 g.
The steps of growing the large-particle diamond under high temperature and high pressure are as follows:
(1) placing the crystal seed 3 in the catalyst cobalt powder 2, and performing compression molding to obtain a cylindrical complex (with the diameter of 6mm and the length of 4mm) with the catalyst coated with the crystal seed; placing the cylindrical complex in diamond powder for compression molding to obtain a cylindrical diamond growth blank, wherein the diameter of the cylindrical diamond growth blank is 10mm, the length of the cylindrical diamond growth blank is 8mm, and the cylindrical diamond growth blank is matched with an inner cavity of a high-temperature high-pressure device matched with a hinge type cubic press;
(2) combining the diamond growth blank obtained in the step (1) with a high-temperature high-pressure device matched with a hinge type cubic press to form a synthetic block shown in the figure 2; putting the synthetic block into a hinge type cubic press, pressurizing to 5.5GPa at the pressure increasing rate of 10GPa/h, heating to 1350 ℃ at the temperature increasing rate of 150 ℃/min, and maintaining the pressure and the temperature for 6h under the pressure and the temperature to grow the diamond;
(3) after the pressure maintaining and heat preservation are finished, cooling to room temperature at the cooling rate of 200 ℃/min, then reducing the pressure to normal pressure at the pressure reduction rate of 10GPa/h, then returning the hinge type cubic press, taking out the block body of the diamond coated by the residual carbon source graphite and the catalyst cobalt, knocking the block body to remove the residual graphite on the surface layer, and then putting the rod body of the diamond coated by the cobalt into HNO with the mass concentration of 25%3Heating the solution to boiling to remove cobalt to obtain diamond crystals, and cleaning the diamond crystals with deionized water to remove residual HNO3Drying at 60 deg.C to remove water on the surface, and storing.
The diamond synthesized in this example was single crystal diamond having a grain size of about 2024 μm, and its SEM image is shown in fig. 10.

Claims (9)

1. A method for growing large-particle diamond at high temperature and high pressure takes seed crystal, catalyst and carbon source as raw materials, and is characterized by comprising the following process steps:
(1) placing the seed crystal in a catalyst for compression molding to obtain a catalyst-coated seed crystal complex, and then coating the complex with a carbon source to form a diamond growth blank, wherein the external shape and size of the diamond growth blank are matched with those of an inner cavity of a high-temperature and high-pressure device matched with static and high-pressure equipment;
(2) combining the diamond growth blank obtained in the step (1) with a high-temperature high-pressure device matched with static high-pressure equipment to form a synthetic block, then putting the synthetic block into the static high-pressure equipment, firstly pressurizing to the diamond growth pressure, then heating to the diamond growth temperature, maintaining the pressure and preserving the heat for growth;
(3) and after the pressure maintaining and heat preservation are finished, firstly cooling to room temperature, then reducing the pressure to normal pressure, then returning the static high-pressure equipment, taking out the block body of the diamond coated by the residual carbon source and the catalyst, and removing the residual carbon source and the catalyst of the block body to obtain the diamond.
2. The method for growing large granular diamond at high temperature and high pressure according to claim 1, wherein the step (1) of wrapping the composite body with a carbon source is performed by pressing the composite body in a carbon source to form a diamond growth body; or pressing the carbon source into an inclusion, wherein the shape and the size of the inner cavity of the inclusion are matched with the external shape and the size of the complex, the shape and the size of the external shape and the size of the inclusion are matched with the shape and the size of the inner cavity of a high-temperature and high-pressure device matched with static and high-pressure equipment, and combining the complex and the inclusion to form the diamond growth blank.
3. A method for growing large-grain diamond according to claim 1 or 2, wherein the number of the seed crystal is one or more, the catalyst is in an amount capable of completely wrapping the seed crystal and satisfying the growth space of the seed crystal, and the carbon source is in an amount capable of completely wrapping the composite body and satisfying the requirement of the expected growth size of the diamond.
4. The method for growing large-particle diamond under high temperature and high pressure according to claim 1 or 2, wherein the diamond in the step (2) has a growth pressure P of 4GPa < P <15GPa, and a growth temperature T of the diamond of 1000 ℃ < T <3000 ℃; the pressure rise rate during pressurization is not more than 60GPa/h, and the temperature rise rate during temperature rise is 0.1-400 ℃/min.
5. The method for rapidly growing large-grained diamond under high temperature and high pressure according to claim 3, wherein the growth pressure P of the diamond in the step (2) is 4GPa < P <15GPa, the growth temperature T of the diamond is 1000 ℃ < T <3000 ℃, the pressure increase rate during pressurization is not more than 60GPa/h, and the temperature increase rate during temperature increase is 0.1-400 ℃/min.
6. The method for growing large-grained diamond under high temperature and high pressure according to claim 4, wherein in the step (3), the temperature reduction rate during temperature reduction is not more than 6000 ℃/min, and the pressure reduction rate during pressure reduction is not more than 120 GPa/h.
7. The method for growing large-grained diamond under high temperature and high pressure according to claim 5, wherein in the step (3), the temperature reduction rate during temperature reduction is not more than 6000 ℃/min, and the pressure reduction rate during pressure reduction is not more than 120 GPa/h.
8. The method for growing large-grained diamond under high temperature and high pressure according to claim 1 or 2, wherein the step (3) of removing the residual carbon source adopts a knocking, fracturing or crushing method, and the step of removing the catalyst adopts an acid treatment method, wherein the acid treatment method is to put the block body with the residual carbon source removed into acid liquor and soak the block body at 5-200 ℃ until the catalyst is completely separated from the diamond.
9. The method for growing large-grained diamond under high temperature and high pressure according to claim 8, wherein the acid solution is one of a nitric acid solution, a hydrofluoric acid solution, a hydrochloric acid solution and a sulfuric acid solution, or consists of at least two of a nitric acid solution, a hydrofluoric acid solution, a hydrochloric acid solution and a sulfuric acid solution.
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