PREPARATION AND APPLICATION OF HIGHLY COHERENT DIAMOND NITROGEN VACANCY AND DIAMOND ANVIL

Abstract

Preparations of a highly coherent diamond nitrogen vacancy (NV.sup.−) and a diamond anvil are provided. A graphite is used as a carbon source, a diamond is used as a crystal seed, aluminum/titanium is used as a nitrogen remover, and a single crystal diamond is synthesized under a high temperature and a high pressure, and high-pressure-high-temperature (HPHT) annealing is performed on the synthesized diamond; after the annealing, multiple NV.sup.−s are generated in <100> and <311> crystal orientation growth regions from scratch, while native NV.sup.−s in a <111> crystal orientation growth region are disappeared; and the <100> and <311> crystal orientation growth regions do not contain defects related to ferromagnetic elements. The high-density and highly coherent NV.sup.−s are produced under nondestructive conditions, and the diamond anvil with controlled NV.sup.− depths are prepared to achieve a precise detection of the NV.sup.− at a pressure above 60 GPa.

Claims

1. A diamond nitrogen vacancy formation method, comprising: synthesizing a single crystal diamond with a nitrogen content of 1˜400 parts per million (ppm) under a target temperature and a target pressure by using an iron-nickel catalyst system, taking a graphite as a carbon source, a diamond as a crystal seed, and aluminum/titanium (Al/Ti) as a nitrogen remover; and regulating a volume ratio of a <100> crystal orientation growth region and a <111> crystal orientation growth region of the single crystal diamond according to selections of the crystal seed and a growth temperature; annealing the single crystal diamond with an annealing pressure of 4.5˜6.5 gigapascal (GPa) and an annealing temperature of 1400˜1800 centigrade (° C.); wherein after the annealing, nitrogen vacancies are generated from scratch in the <100> crystal orientation growth region while native nitrogen vacancies in the <111> crystal orientation growth region are disappeared; when the single crystal diamond has a <311> crystal orientation growth region, nitrogen vacancies are generated in the <311> crystal orientation growth region, and the <100> and <311> crystal orientation growth regions do not contain defects related to ferromagnetic elements.

2. The diamond nitrogen vacancy formation method according to claim 1, wherein the graphite is a graphite with a purity equal to or greater than 99.9%, the target pressure is in a range of 5.0 GPa to 6.5 GPa, the target temperature is in a range of 1350° C. to 1850° C., and a time for keeping the temperature is in a range of 10 h to 60 h.

3. A method for preparing a diamond anvil, comprising the following steps: (1) using an iron-nickel catalyst system, taking a high-purity graphite as a carbon source, and taking Al/Ti as a nitrogen remover, synthesizing a single crystal diamond with a nitrogen content in a range of 0 ppm to 400 ppm by keeping a temperature of 1350˜1850° C. for 10˜60 h at a pressure of 5.0˜6.5 GPa; wherein a volume ratio of a <100> crystal orientation growth region and a <111> crystal orientation growth region of the single crystal diamond is regulated by selections of a crystal seed and a growth temperature; (2) performing annealing at an annealing pressure in a range of 4.5 GPa to 6.5 GPa, an annealing temperature in a range of 1400° C. to 1800° C., and an annealing time in a range of 1 h to 20 h; wherein after the annealing, nitrogen vacancies are generated from scratch in the <100> crystal orientation growth region, while native nitrogen vacancies in the <111> crystal orientation growth region are disappeared; and when the single crystal diamond has a <311> crystal orientation growth region, nitrogen vacancies are generated in the <311> crystal orientation growth region; and the <100> and <311> crystal orientation growth regions do not contain defects related to ferromagnetic elements; and (3) performing cutting on the single crystal diamond by placing an anvil surface inside one of the <100> and <311> crystal orientation growth regions, and placing a main body of the diamond anvil in the <111> crystal orientation growth region according to nitrogen vacancy depth requirements.

4. The method for preparing the diamond anvil according to claim 3, wherein orders of the annealing and the cutting are exchanged.

5. The diamond anvil prepared by the method according to claim 3, wherein a ratio of a depth of the nitrogen vacancies to a height of the diamond anvil is greater than 0 and less than 1.

6. The diamond anvil according to claim 5, wherein the diamond anvil is applied in a quantum sensor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG. 1A is a schematic diagram showing a fluorescence spectrum of a <111> crystal orientation growth region before and after annealing at different annealing temperatures according to an embodiment 1 of the disclosure.

[0021] FIG. 1B is a schematic diagram showing a fluorescence spectrum of a <311> crystal orientation growth region before and after annealing at different annealing temperatures according to an embodiment of the disclosure.

[0022] FIG. 2 illustrates a fluorescence mapping diagram of each crystal orientation growth region before and after the annealing according to the embodiment 1 of the disclosure, in which a illustrates a distribution of the nitrogen vacancies in different crystal orientations before and after the annealing; and b illustrates the distribution of annealed nickel-related defects in the different crystal orientations before and after the annealing.

[0023] FIG. 3A is a schematic diagram showing a fluorescence spectrum of a <111> crystal orientation growth region before and after annealing at different annealing temperatures.

[0024] FIG. 3B is a schematic diagram showing a fluorescence spectrum of a <100> crystal orientation growth region before and after annealing at different annealing temperatures.

[0025] FIG. 4 illustrates a schematic diagram of the diamond anvil cutting.

[0026] FIG. 5 illustrates a schematic diagram of a diamond anvil.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiment 1

[0027] A method for preparing a highly coherent diamond anvil includes following steps.

[0028] (1) A Synthesis of a Diamond Containing High Quality Nitrogen Vacancies.

[0029] An iron-nickel catalyst system is used, a high-purity flaky graphite is used as a carbon source, and aluminum/titanium (Al/Ti) is used as a nitrogen remover, a <100> crystallographic plane of the diamond is used as a crystal seed, and a single crystal diamond is synthesized at 5.5 gigapascal (GPa) and 1460 centigrade (° C.) for 60 hours (h). The synthesized single crystal diamond has a nitrogen content of 20˜80 ppm in a <100> crystal orientation growth region, and a nitrogen content of 200˜300 ppm in a <111> crystal orientation growth region.

[0030] (2) Annealing

[0031] The HPHT annealing is performed on the single crystal diamond at an annealing pressure of 5 GPa and respective annealing temperatures of 1400° C., 1500° C., 1600° C. and 1700° C. for 4 h. There is no nitrogen vacancy on the <111> crystal orientation growth region of the single crystal diamond, and a content of nitrogen vacancies in the <311> and <100> crystal orientation growth regions is up to 10000/cubic micrometer (/μm.sup.3), and the coherence time is about 52 microseconds (μs).

[0032] (3) Cutting of Diamond Anvil

[0033] The cutting is performed on the single crystal diamond by placing an anvil surface in the <311> crystal orientation growth region and another main body in the <111> crystal orientation growth region. A thickness of the anvil surface is 15 micrometers (μm), and a depth of the nitrogen vacancies in the obtained diamond anvil is 15 μm.

[0034] As shown in FIG. 1A and FIG. 1B, through a fluorescence mapping analysis: after the annealing, the nitrogen vacancies are presented only in the <311> and <100> crystal orientation growth regions, native nitrogen vacancies in the <111> crystal orientation growth region are disappeared, and the <311> and <100> crystal orientation growth regions do not contain nickel-related defects; and zero-phonon-line (ZPL) FWHM of the nitrogen vacancies generated in the <100> and <311> crystal orientation growth regions is comparable to ZPL FWHM of the nitrogen vacancies in high-purity diamond.

Embodiment 2

[0035] A method for preparing a highly coherent diamond anvil includes following steps.

[0036] (1) A Synthesis of a Diamond Containing High Quality Nitrogen Vacancies.

[0037] An iron-nickel catalyst system is used, a high-purity flaky graphite is used as a carbon source, and Al/Ti is used as a nitrogen remover, a <111> crystallographic plane of the diamond is used as a crystal seed, and a single crystal diamond is synthesized at 5.5 GPa and 1370° C. for 60 h.

[0038] (2) Annealing

[0039] The HPHT annealing is performed on the single crystal diamond at an annealing pressure of 4.5 GPa and respective annealing temperatures of 1300° C., 1400° C., 1500° C., and 1600° C. for 6 h. Native nitrogen vacancies on the <111> crystal orientation growth region are disappeared under annealing conditions higher than 1400° C., the multiple nitrogen vacancies are generated in the <100> crystal orientation growth region, the <100> crystal orientation growth region does not contain nickel-related curves; and ZPL FWHM of the nitrogen vacancies generated in the <100> crystal orientation growth region is comparable to the ZPL FWHM of the nitrogen vacancies in high-purity diamond.

[0040] (3) Cutting of Diamond Anvil

[0041] The cutting is performed on the single crystal diamond by placing an anvil surface in the <100> crystal orientation growth region and another main body in the <111> crystal orientation growth region. A thickness of the anvil surface is 15 μm, and a depth of the nitrogen vacancies in the obtained diamond anvil is 15 μm.

[0042] As shown in FIG. 2, results further demonstrate that after the annealing, the nitrogen vacancies only present in the <100> crystal orientation growth region.

Embodiment 3

[0043] A method for preparing a highly coherent diamond anvil includes following steps.

[0044] (1) A Synthesis of a Diamond Containing High Quality Nitrogen Vacancies.

[0045] An iron-nickel catalyst system is used, a flaky graphite with a purity equal to or greater than 99.9% is used as a carbon source, and Al/Ti is used as a nitrogen remover, a <111> crystallographic plane of the diamond is used as a crystal seed, and a single crystal diamond is synthesized at 6.5 GPa and 1350° C. for 10 h.

[0046] (2) Annealing

[0047] The HPHT annealing is performed on the single crystal diamond at an annealing pressure of 6.5 GPa and an annealing temperature of 1600° C. for 6 h. Native nitrogen vacancies in the <111> crystal orientation growth region are disappeared, the multiple nitrogen vacancies are generated in the <100> crystal orientation growth region, and the <100> crystal orientation growth region does not contain nickel-related curves; and ZPL FWHM of the nitrogen vacancies generated in the <100> crystal orientation growth region is comparable to the ZPL FWHM of the nitrogen vacancies in high-purity diamond.

[0048] (3) Cutting of Diamond Anvil

[0049] The cutting is performed on the single crystal diamond by placing an anvil surface in the <100> crystal orientation growth region and another main body in the <111> crystal orientation growth region. A thickness of the anvil surface is 15 μm, and a depth of the nitrogen vacancies in the obtained diamond anvil is 15 μm.

[0050] After the annealing, the nitrogen vacancies only present in the <100>crystal orientation growth region.

Embodiment 4

[0051] A method for preparing a highly coherent diamond anvil includes following steps.

[0052] (1) A Synthesis of a Diamond Containing High Quality Nitrogen Vacancies.

[0053] An iron-nickel catalyst system is used, a flaky graphite with a purity of over 99.9% is used as a carbon source, and Al/Ti is used as a nitrogen remover, a <100> crystallographic plane of the diamond is used as a crystal seed, and a single crystal diamond is synthesized at 5 GPa and 1850° C. for 60 h.

[0054] (2) Annealing

[0055] The HPHT annealing is performed on the single crystal diamond at an annealing pressure of 4.5 GPa, an annealing temperature of 1800° C., and an annealing time of 20 h. There are no nitrogen vacancies on the <111> crystal orientation growth region.

[0056] (3) Cutting of Diamond Anvil

[0057] The cutting is performed on the single crystal diamond by placing an anvil surface in the <311> crystal orientation growth region and another main body in the <111> crystal orientation growth region. A thickness of the anvil surface is 15 μm, and a depth of the nitrogen vacancies in the obtained diamond anvil is 15 μm.

[0058] After the annealing, the nitrogen vacancies only present in the <311> and <100> crystal orientation growth regions, the native nitrogen vacancies in the <111> crystal orientation growth region are disappeared, and the <311> and <100> crystal orientation growth regions do not contain nickel-related defects; and ZPL FWHM of the nitrogen vacancies generated in the <100> and <311> crystal orientation growth regions is comparable to the ZPL FWHM of the nitrogen vacancies in high-purity diamond.