Methods of manufacturing flourescent nanodiamond particles

Abstract

A method may mix a nanodiamond powder with a salt to create a nanodiamond-salt mixture. A method may sinter the nanodiamond-salt mixture under high-pressure high-temperature (HPHT) conditions for a sintering duration to create a sintered nanodiamond-salt block. A method may wash at least a portion of the sintered nanodiamond-salt block with a fluid. A method may dissolve at least a portion of the salt from at least one fluorescent nanodiamond (FND) of the sintered nanodiamond-salt block. A method may separate a fluorescent nanodiamond from the salt.

Description

PATENTDocket No. IS22.0489-WO-PCTMETHODS OF MANUFACTURING FLOURESCENT NANODIAMOND PARTICLESCROSS REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to and the benefit of United States Provisional Patent Application No. 63 / 689,373 entitled METHODS OF MANUFACTURING FLOURESCENT NANODIAMOND PARTICLES filed August 30, 2024, the disclosure of which is incorporated herein by reference.BACKGROUND OF THE DISCLOSURE

[0002] Fluorescent nanodiamonds (FNDs) have optical centers that respond to a variety of external stimuli, allowing the FNDs to be beneficial in a variety of sensing and imaging techniques. Additionally, FNDs are very stable and biocompatible for use in medical sensing and imaging techniques. Conventional manufacturing of FNDs can introduce lattice defects and surface damage that adversely affect the performance of the FNDs and the yield of manufacturing.SUMMARY

[0003] In some aspects, the techniques described herein relate to a method of manufacturing fluorescent nanodiamond, the method including: mixing a nanodiamond powder with a salt to create a nanodiamond-salt mixture; sintering the nanodiamond-salt mixture under high-pressure high-temperature (HPHT) conditions for a sintering duration to create a sintered nanodiamond-salt block; washing at least a portion of the sintered nanodiamond-salt block with a fluid; dissolving at least a portion of the salt from at least one fluorescent nanodiamond (FND) of the sintered nanodiamond-salt block; and separating a fluorescent nanodiamond from the salt.

[0004] In some aspects, the techniques described herein relate to a method of manufacturing fluorescent nanodiamond, the method including: adding a fluid source to a nanodiamond powder; sintering the nanodiamond powder under high-PATENTDocket No. IS22.0489-WO-PCT pressure high-temperature (HPHT) conditions for a sintering duration to create a sintered nanodiamond block, wherein at least a portion of the fluid source changes to a supercritical fluid at the HPHT conditions; washing at least a portion of the sintered nanodiamond block with a fluid; and separating a fluorescent nanodiamond from the fluid.

[0005] This summary is provided to introduce a selection of concepts that are further described in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter. Additional features and aspects of embodiments of the disclosure will be set forth herein, and in part will be obvious from the description, or may be learned by the practice of such embodiments.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] In order to describe the manner in which the above-recited and other features of the disclosure can be obtained, a more particular description will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. For better understanding, the like elements have been designated by like reference numbers throughout the various accompanying figures. While some of the drawings may be schematic or exaggerated representations of concepts, at least some of the drawings may be drawn to scale. Understanding that the drawings depict some example embodiments, the embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:

[0007] FIG. 1 is a schematic representation of a diamond lattice with a nitrogenvacancy;

[0008] FIG. 2 is a schematic cross-sectional view of high-pressure, high- temperature press;

[0009] FIG. 3 is a flowchart illustrating a method of manufacturing fluorescent nanodiamond, according to at least some embodiments of the present disclosure;PATENTDocket No. IS22.0489-WO-PCT

[0010] FIG. 4 is a detail cross-sectional view of a sintered nanodiamond-salt block, according to at least some embodiments of the present disclosure;

[0011] FIG. 5 is a flowchart illustrating another method of manufacturing fluorescent nanodiamond, according to at least some embodiments of the present disclosure;

[0012] FIG. 6 is a chart of the relative pressure and density of water supercritical fluid relative to temperature, according to at least some embodiments of the present disclosure; and

[0013] FIG. 7 is a detail cross-sectional view of a sintered nanodiamond-salt block with supercritical fluid in pores, according to at least some embodiments of the present disclosure.DETAILED DESCRIPTION

[0014] The present disclosure relates generally to system and methods of manufacturing fluorescent nanodiamonds. More particularly, the present disclosure relates to the refinement of nanodiamond powder into a fluorescent nanodiamond through sintering. In some embodiments, a nanodiamond powder containing a plurality of nanodiamond particles is subjected to high-pressure, high- temperature (HPHT) conditions. The HPHT conditions impart energy to the crystal lattice of the nanodiamond particle(s) and increase atomic mobility in the crystal lattice. In some embodiments, naturally occurring nitrogen atoms in the crystal lattice arrange adjacent to lattice vacancies and form a nitrogen-vacancy (NV) center. An NV center, when excited by an external energy source, fluoresces. The HPHT conditions and increased atomic mobility in the crystal lattice allow the formation of the NV centers in the nanodiamond to create fluorescent nanodiamond (FND).

[0015] In some embodiments, the nanodiamond powder can be sintered with a second material to limit and / or prevent agglomeration and / or bonding of the nanodiamond particles to one another during the sintering process. Conventional manufacturing of FND includes the manufacturing of micrometer-scale particlesPATENTDocket No. IS22.0489-WO-PCT that are subsequently milled or ground to a nanoscale. For example, a particle with a particle size greater than 1 micrometer (pm) may be milled or ground to a particle or plurality of particles with a particle size of 100 nanometers (nm) or less. However, milling and / or grinding of the particles can, itself, introduce damage to the lattice (e.g., reduce the crystallinity) of the diamond grains. The damage to the lattice can adversely affect the performance of the FND and / or reduce the manufacturing yield. In some embodiments, applying HPHT conditions to the nanodiamond particles of the nanodiamond powder increases the crystallinity of the lattice and / or reduces internal strain in the lattice while increasing the NV center count of nanodiamond particle. In at least some embodiments, manufacturing of FND via HPHT processing of nanodiamond powder provides increased performance, increased yield, decreased cost, or combinations thereof relative to conventional FND manufacturing.

[0016] In some embodiments, sintering of nanodiamond powder can promote agglomeration of nanodiamond particles, which can require additional processing to separate the nanodiamond particles. In some examples, such additional processing can introduce damage to the diamond lattice and / or reduce a yield of the FND manufacturing. For example, agglomeration can occur at HPHT conditions from interstitial growth between particles, mechanical locking of particles, or other diamond-to-diamond bonding of the nanodiamond particles. The additional processing can include grinding, milling, or crushing of the agglomeration(s) to separate the nanodiamond particles. In some embodiments, manufacturing FND according to the present disclosure further includes introducing, mixing, or otherwise adding at least one secondary material to the nanodiamond powder to limit and / or prevent the agglomeration of the nanodiamond particles.

[0017] In some embodiments, the nanodiamond powder is mixed with a salt to form a nanodiamond-salt mixture prior to sintering at HPHT conditions. The salt may flow in the HPHT conditions into pores or other space between the nanodiamond particles. The presence of the salt between the nanodiamond particles limits and / or prevents agglomeration. In some embodiments, thePATENTDocket No. IS22.0489-WO-PCT nanodiamond powder or nanodiamond-salt mixture includes a fluid source that, under HPHT conditions, forms a supercritical fluid between the nanodiamond particles. In some embodiments, the supercritical fluid enters smaller pores and / or spaces between nanodiamond particles than a salt and limits and / or prevents agglomeration.

[0018] The nanodiamond particles may be loosely bonded to one another after sintering at HPHT temperatures. In some embodiments, a method according to the present disclosure includes separating the FND particles without milling or grinding. In some examples, the loosely bonded FND particles may be separated by a subsequent heat-treatment after cooling from sintering. In some examples, the loosely bonded FND particles may be separated by a subsequent washing in a solvent or other fluid after cooling from sintering. In some examples, the loosely bonded FND particles may be separated by dissolving the salt in a solvent after cooling from sintering. In some examples, the loosely bonded FND particles may be separated by tumbling or agitation after cooling from sintering. In some examples, the loosely bonded FND particles may be separated by combination of the foregoing examples.

[0019] FIG. 1 is a diamond crystal lattice 100 including a plurality of carbon atoms 102 covalently bonded to one another. In some embodiments, a diamond crystal lattice 100 includes at least one nitrogen atom 104 adjacent to (i.e., forms a near east-neighbor pair with) a vacancy 106 in the lattice. The nitrogen atom 104 has 5 valence electrons, with three valence electrons covalently bonded to an adjacent carbon atom 102 and two valence electrons in a lone pair. The nitrogen atom 104 adjacent to the vacancy 106 creates a photoluminescent point defect. The NV center emits light when externally excited, and FND can be useful in a variety of sensors including optically detected magnetic resonance (ODMR).

[0020] While FIG. 1 illustrates a single nitrogen atom 104 adjacent to the vacancy 106 in an NV center, in some embodiments, more than one nitrogen atom 104 is adjacent to the vacancy 106. For example, a vacancy 106 with two adjacent nitrogen atoms 104 forms an NVN (or NV2) center, and a vacancy 106 with threePATENTDocket No. IS22.0489-WO-PCT adjacent nitrogen atoms 104 forms an NV3 center. An NV center, an NVN center, and an NV3 center each have different optical properties. It should be understood that, as used herein, “NV center” refers collectively to an NV center, an NVN center, and an NV3 center unless otherwise noted.

[0021] In an unprocessed diamond lattice, nitrogen atoms 104 are naturally occurring defects. Methods described herein including HPHT conditions, in some embodiments, create vacancies 106 in a diamond crystal lattice 100 to produce NV centers. Methods described herein including HPHT conditions, in some embodiments, increase atomic mobility in the diamond crystal lattice 100 to allow diffusion and / or migration of nitrogen atoms 104 and / or vacancies 106 in a diamond crystal lattice 100 to produce NV centers. In some embodiments, methods described herein including HPHT conditions create vacancies 106 and increase atomic mobility in the diamond crystal lattice 100 to allow diffusion and / or migration of nitrogen atoms 104 and / or vacancies 106 in a diamond crystal lattice 100 to produce NV centers.

[0022] FIG. 2 is a schematic illustration of an HPHT press 208 in which one or more movable anvils 210 apply force to a can 212. In some embodiments, the can 212 contains a nanodiamond powder 214. In some embodiments, the can 212 contains a nanodiamond powder 214 and a salt in a nanodiamond-salt mixture. In some embodiments, the nanodiamond-salt mixture is at least 15% salt by weight percentage. In some embodiments, the nanodiamond-salt mixture is at least 25% salt by weight percentage. In some embodiments, the nanodiamond powder 214 has an average particle size no more than 100 nm. In some embodiments, the nanodiamond powder 214 has an average particle size no more than 50 nm.

[0023] In some embodiments, at least some of the nanodiamond particles of the nanodiamond powder 214 are irradiated prior to loading into the can 212. Irradiated nanodiamond particles may have lattice defects that include vacancies (such as a vacancy described in relation to FIG. 1 ). In some embodiments, an irradiated nanodiamond particle includes more vacancies than a non-irradiated nanodiamond particle. An irradiated nanodiamond particle, therefore, producesPATENTDocket No. IS22.0489-WO-PCT more NV centers. In some embodiments, the crystal lattice of the irradiated nanodiamond particle has a vacancy count greater than 1000 parts per million (ppm). In some embodiments, the crystal lattice of the irradiated nanodiamond particle has a vacancy count greater than 5000 ppm. In some embodiments, the irradiated nanodiamond particle has a greater amount of damage to the crystal lattice relative to a non-irradiated nanodiamond particle. In such embodiment, sintering at HPHT conditions may repair at least a portion of the damage to the crystal lattice (e.g., increase crystallinity of the crystal lattice), which may improve optical performance of the resulting FND.

[0024] In some embodiment, a fluid source is included in the can 212 with the nanodiamond powder 214. As will described in more detail herein, the fluid source may convert to a supercritical fluid at HPHT conditions in the press 208 during sintering. The supercritical fluid may limit and / or prevent diamond-to-diamond bonding to improve yield.

[0025] The press 208 may provide an isotropic pressure to the can 212 and / or the nanodiamond powder 214 therein. In some embodiments, the press 208 provides a substantially uniform heat to the can 212 and / or the nanodiamond power 214 therein to limit and / or prevent temperature gradients across the can 212 and / or the nanodiamond power 214.

[0026] FIG. 3 is a flowchart illustrating an embodiment of a method 316 of manufacturing FND. In some embodiments, the method 316 includes mixing a nanodiamond powder with a salt powder to create a nanodiamond-salt mixture at 318. In some embodiments, the salt is a binary salt. For example, the salt may be an ionic compound with equal atomic stoichiometry of a first element and a second element. In at least one example, the salt is sodium chloride (NaCI). In some embodiments, the nanodiamond-salt mixture is no more than 25% salt by weight. In some embodiments, the nanodiamond-salt mixture is no more than 15% salt by weight. In some embodiments, the nanodiamond-salt mixture is homogenous. In some embodiments, the nanodiamond-salt mixture has a gradient of at least salt concentration in the mixture, such as in the can described in relation to FIG. 2.PATENTDocket No. IS22.0489-WO-PCT

[0027] In some embodiments, the method 316 further includes sintering the nanodiamond-salt mixture under HPHT conditions for a sintering duration to create a sintered nanodiamond-salt block at 320. The pressure of the HPHT condition is, in some embodiments, a pressure of no less than 4 gigapascal (GPa) during the sintering duration. In some embodiments, the pressure of the HPHT condition is a pressure of no more than 9 GPa during the sintering duration. In some embodiments, the pressure of the HPHT condition is a pressure of no less than 4 GPa and no more than 9 GPa during the sintering duration. In some embodiments, the pressure during the sintering duration is substantially constant. For example, the pressure during the sintering duration may not vary by more than 10%. In some embodiments, the pressure is continuously increased during the sintering duration. In some embodiments, the pressure is continuously decreased during the sintering duration.

[0028] The temperature of the HPHT condition is, in some embodiments, a temperature of no less than 1000°C during the sintering duration. In some embodiments, the temperature of the HPHT condition is a temperature of no more than 2500°C during the sintering duration. In some embodiments, the temperature of the HPHT condition is a temperature of no less than 1000°C and no more than 2500°C during the sintering duration. In some embodiments, the temperature of the HPHT condition is a temperature of no less than 1200°C and no more than 1800°C during the sintering duration. In some embodiments, the temperature of the HPHT condition is a temperature of approximately 1650°C. In some embodiments, the temperature during the sintering duration is substantially constant. For example, the temperature during the sintering duration may not vary by more than 10%. In some embodiments, the temperature is continuously increased during the sintering duration. In some embodiments, the temperature is continuously decreased during the sintering duration.

[0029] In some embodiments, the sintering duration is greater than 1 minute. In some embodiments, the sintering duration is less than 60 minutes. In some embodiments, the sintering duration is between 1 and 60 minutes. During the sintering duration, the salt may plastically deform and / or flow betweenPATENTDocket No. IS22.0489-WO-PCT nanodiamond particles of the nanodiamond powder. The salt present between the nanodiamond particles may limit and / or prevent diamond-to-diamond bonding or other agglomeration of the nanodiamond particles during the HPHT conditions.

[0030] The HPHT conditions, in some embodiments, create at least one vacancy in the crystal lattice of a nanodiamond particle. For example, the strain on the crystal lattice at the HPHT conditions may cause a dislocation and / or mobility in the lattice that results in a newly created vacancy in the crystal lattice. In some embodiments, the HPHT conditions promote or cause the migration of at least one of a nitrogen atom and a vacancy within the crystal lattice. For example, the increased pressure and increased temperature of the crystal lattice may allow greater mobility of the nitrogen atom(s) and vacancy(ies) through lattice sites. The mobility of the nitrogen atom(s) and vacancy(ies) and / or the creation of at least one vacancy creates at least one NV center in the nanodiamond particle during the sintering at HPHT conditions.

[0031] During the sintering, an outer region of the nanodiamond particle may graphitize during sintering and be lost from the diamond lattice during subsequent heat-treating. For example, the nanodiamond particles of the nanodiamond powder may experience weight loss between 5 and 10 wt% after heat treating.

[0032] In some embodiments, the method 316 further includes washing at least a portion of the sintered nanodiamond-salt block with a fluid at 322. In some embodiments, the fluid is water. In some embodiments, the fluid is alcohol.

[0033] In some embodiments, the method 316 further includes dissolving at least a portion of the salt from the nanodiamond particles at 324. For example, the fluid may be a polar solvent that dissolves the salt into solution in the solvent. In some examples, the salt may disperse into suspension in the fluid.

[0034] In some embodiments, the method 316 further includes separating an FND from the salt at 326. For example, separating the FND from the salt may include filtering the FND and / or salt from the fluid. In some examples, separating the FND from the salt may include centrifuging the nanodiamond particles andPATENTDocket No. IS22.0489-WO-PCT fluid. The supernatant FND particles may be removed from the fluid and / or salt therein.

[0035] In some embodiments, the method 316 includes separating a first FND from a second FND. In some examples, a first FND and a second FND loosely bond to one another. In some examples, separating a first FND from a second FND may include sonicating the FNDs for a sonication duration between 1 hour and 1 month. In some embodiments, the sonication occurs at 40 kilohertz (kHz) and 110 Watts (W). In some examples, separating a first FND from a second FND may include heat-treating the FNDs. In some embodiments, heat treatment includes heating the FNDs to between 475°C and 525°C for between 1 hour and 5 hours. During heat treatment, loss of a graphitized outer surface weakens the bonding between particles.

[0036] FIG. 4 is a detail cross-sectional view of an embodiment of a sintered nanodiamond block 428 during and / or after sintering at HPHT conditions. In some embodiments, the sintered nanodiamond block 428 includes a plurality of nanodiamond particles of the nanodiamond powder 414. The nanodiamond particles have salt 430 positioned between and / or around the nanodiamond particles. In some embodiments, the salt 430 penetrates into and fills the pores 432 between the nanodiamond particles to limit and / or prevent agglomeration of the nanodiamond powder 414. In some embodiments, at least some of the pores 432 are too small for the salt to enter. A supercritical fluid has substantially no surface tension and may flow into the small pores 432 between the nanodiamond particles.

[0037] FIG. 5 is a flowchart illustrating an embodiment of another method 532 of manufacturing an FND using a supercritical fluid. In some embodiments, the method 532 includes adding a fluid source to a nanodiamond powder at 534. In some embodiments, adding the fluid source includes mixing the fluid source into the nanodiamond powder. In some embodiments, adding the fluid source includes positioning a separate layer of the fluid source proximate to and / or adjacent to the nanodiamond powder. In some examples, the fluid source may be a separate layerPATENTDocket No. IS22.0489-WO-PCT that is positioned through at least a portion of the nanodiamond powder. In some examples, the fluid source may be a separate layer that is positioned around at least a portion of the nanodiamond powder, such as between the nanodiamond powder and a can as described in relation to FIG. 2.

[0038] The fluid source may be any material that produces a supercritical fluid at HPHT conditions. For example, the fluid source may be a liquid at standard temperature and pressure (STP) and a supercritical fluid at HPHT conditions. In some examples, the fluid source may be liquid water that converts to supercritical H2O at HPHT conditions. In some examples, the fluid source is a solid at STP, such as a wax. In at least one embodiment, the fluid source is a material that decomposes into at least two components between STP and the HPHT conditions, where one of the components is the supercritical fluid at the HPHT conditions. For example, the fluid source may be, produce, or decomposed into at least carbon dioxide, where the carbon dioxide is the supercritical fluid at HPHT conditions.

[0039] In some embodiments, the fluid source is less than 5 percentage by volume (vol%) of the total weight of the nanodiamond powder and the fluid source. In some embodiments, the fluid source is less than 2 wt% of the total weight of the nanodiamond powder and the fluid source.

[0040] In some embodiments, the nanodiamond powder is combined with a salt. In some embodiments, the nanodiamond-salt mixture is no more than 25% salt by weight. In some embodiments, the nanodiamond-salt mixture is no more than 15% salt by weight. In some embodiments, the nanodiamond-salt mixture is homogenous. In some embodiments, the nanodiamond-salt mixture has a gradient of at least salt concentration in the mixture. In some embodiments, the fluid source is less than 5 percentage by volume (vol%) of the total weight of the nanodiamondsalt mixture and the fluid source. In some embodiments, the fluid source is less than 2 wt% of the total weight of the nanodiamond-salt m ixture and the fluid source. The fluid source may be added to the nanodiamond after the salt is added to the nanodiamond powder. For example, the fluid source may be added to aPATENTDocket No. IS22.0489-WO-PCT nanodiamond-salt mixture. In some examples, the fluid source is added to the nanodiamond powder before the salt is added to the nanodiamond powder.

[0041] In some embodiments, the method 532 includes sintering the nanodiamond powder (and optionally a salt) under HPHT conditions for a sintering duration to create a sintered nanodiamond block, wherein at least a portion of the fluid source changes to a supercritical fluid at the HPHT conditions at 536.

[0042] The pressure of the HPHT condition is, in some embodiments, a pressure of no less than 4 gigapascal (GPa) during the sintering duration. In some embodiments, the pressure of the HPHT condition is a pressure of no more than 9 GPa during the sintering duration. In some embodiments, the pressure of the HPHT condition is a pressure of no less than 4 GPa and no more than 9 GPa during the sintering duration. In some embodiments, the pressure during the sintering duration is substantially constant. For example, the pressure during the sintering duration may not vary by more than 10%. In some embodiments, the pressure is continuously increased during the sintering duration. In some embodiments, the pressure is continuously decreased during the sintering duration.

[0043] The temperature of the HPHT condition is, in some embodiments, a temperature of no less than 1000°C during the sintering duration. In some embodiments, the temperature of the HPHT condition is a temperature of no more than 2500°C during the sintering duration. In some embodiments, the temperature of the HPHT condition is a temperature of no less than 1000°C and no more than 2500°C during the sintering duration. In some embodiments, the temperature of the HPHT condition is a temperature of no less than 1200°C and no more than 1800°C during the sintering duration. In some embodiments, the temperature of the HPHT condition is a temperature of approximately 1650°C. In some embodiments, the temperature during the sintering duration is substantially constant. For example, the temperature during the sintering duration may not vary by more than 10%. In some embodiments, the temperature is continuouslyPATENTDocket No. IS22.0489-WO-PCT increased during the sintering duration. In some embodiments, the temperature is continuously decreased during the sintering duration.

[0044] In some embodiments, the sintering duration is greater than 1 minute. In some embodiments, the sintering duration is less than 60 minutes. In some embodiments, the sintering duration is between 1 and 60 minutes. During the sintering duration, the salt may plastically deform and / or flow between nanodiamond particles of the nanodiamond powder. The salt present between the nanodiamond particles may limit and / or prevent diamond-to-diamond bonding or other agglomeration of the nanodiamond particles during the HPHT conditions.

[0045] The HPHT conditions, in some embodiments, create at least one vacancy in the crystal lattice of a nanodiamond particle. For example, the strain on the crystal lattice at the HPHT conditions may cause a dislocation and / or mobility in the lattice that results in a newly created vacancy in the crystal lattice. In some embodiments, the HPHT conditions promote or cause the migration of at least one of a nitrogen atom and a vacancy within the crystal lattice. For example, the increased pressure and increased temperature of the crystal lattice may allow greater mobility of the nitrogen atom(s) and vacancy(ies) through lattice sites. The mobility of the nitrogen atom(s) and vacancy(ies) and / or the creation of at least one vacancy creates at least one NV center in the nanodiamond particle during the sintering at HPHT conditions.

[0046] During the sintering, an outer region of the nanodiamond particle may graphitize during sintering and be lost from the diamond lattice during subsequent heat-treating. For example, the nanodiamond particles of the nanodiamond powder may experience weight loss between 5 and 10 wt% after heat treating.

[0047] In some embodiments, sintering the nanodiamond powder includes flowing the supercritical fluid between nanodiamond particles of the nanodiamond powder. For example, the supercritical fluid has no surface tension, which allows the supercritical fluid to enter small pores. The supercritical fluid between the nanodiamond particles of the nanodiamond powder, in some embodiments, limitsPATENTDocket No. IS22.0489-WO-PCT and / or prevents agglomeration of the nanodiamond powder to increase the yield of FNDs.

[0048] In some embodiments, the method 532 further includes washing at least a portion of the sintered nanodiamond block with a fluid at 538. In some embodiments, the fluid is water. In some embodiments, the fluid is alcohol.

[0049] In some embodiments, the method 532 optionally includes dissolving at least a portion of the optional salt from the nanodiamond particles. For example, the fluid may be a solvent that dissolves the salt into solution in the solvent. In some examples, the salt may disperse into suspension in the fluid.

[0050] In some embodiments, the method 532 further includes separating an FND from the fluid at 540. For example, separating the FND from the salt may include filtering the FND and / or salt from the fluid. In some examples, separating the FND from the salt may include centrifuging the nanodiamond particles and fluid. The supernatant FND particles may be removed from the fluid and / or salt therein.

[0051] In some embodiments, the method 542 optionally includes separating a first FND from a second FND. In some examples, a first FND and a second FND loosely bond to one another. In some examples, separating a first FND from a second FND may include sonicating the FNDs. In some examples, separating a first FND from a second FND may include heat-treating the FNDs.

[0052] FIG. 6 is a chart 642 illustrating an example of pressure and density of water supercritical fluid inside a tantalum canister (such as the can 212 described in relation to FIG. 2) at various temperatures. The density of the supercritical fluid can be adjusted based on adjustments to the pressure and / or temperature of the HPHT conditions. For example, in a method of manufacturing FND such as described in relation to FIG. 5, the supercritical fluid may have a density greater than 1 gram per milliliter (g / ml) at the HPHT conditions. In some examples, the supercritical fluid may have a density greater than 1.1 g / ml at the HPHT conditions.PATENTDocket No. IS22.0489-WO-PCT

[0053] FIG. 7 is a detail cross-sectional view of another embodiment of a sintered nanodiamond block 728. The sintered nanodiamond block 728 includes nanodiamond particles of the nanodiamond powder 712. The sintered nanodiamond block 728 further includes a salt 730 and pores 732. In some embodiments, the pores 732 are too small for the salt to flow into, and the supercritical fluid 744 enters the pores 732. In some embodiments, at least a portion of the sintered nanodiamond block 728 is not filled by the nanodiamond particle(s), the salt 730, or the supercritical fluid 744 and a void 746 is formed. In some embodiments, the sintered nanodiamond block 728 has a void percentage by volume (vol%) at the HPHT conditions is no more than 1vol%.

[0054] Systems, devices, and methods for the manufacturing of FNDs are described herein and at least according to the following clauses:

[0055] Clause 1. A method of manufacturing fluorescent nanodiamond, the method comprising: mixing a nanodiamond powder with a salt to create a nanodiamond-salt mixture; sintering the nanodiamond-salt mixture under high- pressure high-temperature (HPHT) conditions for a sintering duration to create a sintered nanodiamond-salt block; washing at least a portion of the sintered nanodiamond-salt block with a fluid; dissolving at least a portion of the salt from at least one fluorescent nanodiamond (FND) of the sintered nanodiamond-salt block; and separating a fluorescent nanodiamond from the salt.

[0056] Clause 2. The method of clause 1 , wherein the salt is a binary salt.

[0057] Clause 3. The method of any preceding clause, wherein the salt is sodium chloride.

[0058] Clause 4. The method of any preceding clause, wherein the nanodiamond-salt mixture is no less than 15% salt by weight.

[0059] Clause 5. The method of any preceding clause, wherein the nanodiamond-salt mixture is no less than 25% salt by weight.

[0060] Clause 6. The method of any preceding clause, wherein the nanodiamond powder has an average particle size less than 100 nanometers (nm).PATENTDocket No. IS22.0489-WO-PCT

[0061] Clause 7. The method of any preceding clause, wherein the nanodiamond powder has an average particle size less than 50 nm.

[0062] Clause 8. The method of any preceding clause, wherein the HPHT conditions include a pressure between 4 gigapascal (GPa) and 9 GPa.

[0063] Clause 9. The method of any preceding clause, wherein the HPHT conditions include a temperature between 1000°C and 2500°C.

[0064] Clause 10. The method of any preceding clause, wherein the sintering duration is between 1 minute and 60 minutes.

[0065] Clause 11. The method of any preceding clause, further comprising sonicating at least a first FND and a second FND of the sintered nanodiamond-salt block.

[0066] Clause 12. The method of any preceding clause, further comprising heat treating the FND.

[0067] Clause 13. A method of manufacturing fluorescent nanodiamond, the method comprising: adding a fluid source to a nanodiamond powder; sintering the nanodiamond powder under high-pressure high-temperature (HPHT) conditions for a sintering duration to create a sintered nanodiamond block, wherein at least a portion of the fluid source changes to a supercritical fluid at the HPHT conditions; washing at least a portion of the sintered nanodiamond block with a fluid; and separating a fluorescent nanodiamond from the fluid.

[0068] Clause 14. The method of clause 13, wherein the fluid source is liquid water.

[0069] Clause 15. The method of clause 13, wherein the fluid source is wax.

[0070] Clause 16. The method of clause 13, wherein the supercritical fluid is carbon dioxide.

[0071] Clause 17. The method of any of clauses 13-16, wherein the supercritical fluid has a density greater than 1 gram per milliliter (g / ml) at the HPHT conditions.PATENTDocket No. IS22.0489-WO-PCT

[0072] Clause 18. The method of any of clauses 13-17, wherein the supercritical fluid has a density greater than 1.1 gram per milliliter (g / ml) at the HPHT conditions.

[0073] Clause 19. The method of any of clauses 13-18, wherein adding a fluid source to the nanodiamond powder includes mixing the fluid source with the nanodiamond powder.

[0074] Clause 20. The method of any of clauses 13-19, wherein adding a fluid source to the nanodiamond powder includes adding a separate layer to the nanodiamond powder.

[0075] Clause 21. The method of any of clauses 13-20, further comprising mixing a nanodiamond powder with a salt powder to create a nanodiamond-salt mixture prior to sintering.

[0076] Clause 22. The method of any of clauses 13-21 , wherein the fluid source is less than 5 percentage by volume (vol%) of a total weight of the nanodiamondsalt mixture and the fluid source.

[0077] Clause 23. The method of any of clauses 13-22, wherein the fluid source is no more than 2 percentage by weight (wt%) of a total weight of the nanodiamond-salt mixture and the fluid source.

[0078] Clause 24. The method of any of clauses 13-23, wherein a void percentage by volume (vol%) in a sintered block of the nanodiamond-salt mixture and supercritical fluid at the HPHT conditions is no more than 1vol%.

[0079] Clause 25. The method of any of clauses 13-24, wherein separating the fluorescent nanodiamond from the fluid includes removing supernatant nanodiamonds from the fluid.

[0080] Clause 26. The method of any preceding clause, wherein the nanodiamond powder includes an irradiated diamond particle.

[0081] Clause 27. The method of clause 26, wherein the irradiated diamond particle has a greater than 1000 parts per million (ppm) vacancy count.PATENTDocket No. IS22.0489-WO-PCT

[0082] Clause 28. The method of clause 27, wherein the irradiated diamond particle has greater than 5000 ppm vacancy count.

[0083] One or more specific embodiments of the present disclosure are described herein. These described embodiments are examples of the presently disclosed techniques. Additionally, in an effort to provide a concise description of these embodiments, not all features of an actual embodiment may be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous embodiment-specific decisions will be made to achieve the developers’ specific goals, such as compliance with system -related and business-related constraints, which may vary from one embodiment to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

[0084] Additionally, it should be understood that references to “one embodiment” or “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. For example, any element described in relation to an embodiment herein may be combinable with any element of any other embodiment described herein. Numbers, percentages, ratios, or other values stated herein are intended to include that value, and also other values that are “about” or “approximately” the stated value, as would be appreciated by one of ordinary skill in the art encompassed by embodiments of the present disclosure. A stated value should therefore be interpreted broadly enough to encompass values that are at least close enough to the stated value to perform a desired function or achieve a desired result. The stated values include at least the variation to be expected in a suitable manufacturing or production process, and may include values that are within 5%, within 1 %, within 0.1 %, or within 0.01 % of a stated value.

[0085] A person having ordinary skill in the art should realize in view of the present disclosure that equivalent constructions do not depart from the spirit andPATENTDocket No. IS22.0489-WO-PCT scope of the present disclosure, and that various changes, substitutions, and alterations may be made to embodiments disclosed herein without departing from the spirit and scope of the present disclosure. Equivalent constructions, including functional “means-plus-function” clauses are intended to cover the structures described herein as performing the recited function, including both structural equivalents that operate in the same manner, and equivalent structures that provide the same function. It is the express intention of the applicant not to invoke means-plus-function or other functional claiming for any claim except for those in which the words ‘means for’ appear together with an associated function. Each addition, deletion, and modification to the embodiments that falls within the meaning and scope of the claims is to be embraced by the claims.

[0086] The terms “approximately,” “about,” and “substantially” as used herein represent an amount close to the stated amount that is within standard manufacturing or process tolerances, or which still performs a desired function or achieves a desired result. For example, the terms “approximately,” “about,” and “substantially” may refer to an amount that is within less than 5% of, within less than 1 % of, within less than 0.1 % of, and within less than 0.01 % of a stated amount. Further, it should be understood that any directions or reference frames in the preceding description are merely relative directions or movements. For example, any references to “up” and “down” or “above” or “below” are merely descriptive of the relative position or movement of the related elements. Additionally, as used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items.

[0087] The present disclosure may be embodied in other specific forms without departing from its spirit or characteristics. The described embodiments are to be considered as illustrative and not restrictive. The scope of the disclosure is, therefore, indicated by the appended claims rather than by the foregoing description. Changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

PATENTDocket No. IS22.0489-WO-PCTCLAIMSWhat is claimed is:

1. A method of manufacturing fluorescent nanodiamond, the method comprising: mixing a nanodiamond powder with a salt to create a nanodiamond-salt mixture; sintering the nanodiamond-salt mixture under high-pressure high- temperature (HPHT) conditions for a sintering duration to create a sintered nanodiamond-salt block; washing at least a portion of the sintered nanodiamond-salt block with a fluid; dissolving at least a portion of the salt from at least one fluorescent nanodiamond (FND) of the sintered nanodiamond-salt block; and separating the FND from the salt.

2. The method of claim 1 , wherein the salt is a binary salt.

3. The method of claim 1 , wherein the salt is sodium chloride.

4. The method of claim 1 , wherein the nanodiamond-salt mixture is no less than15% salt by weight.

5. The method of claim 1 , wherein the nanodiamond-salt mixture is no less than25% salt by weight.

6. The method of claim 1 , wherein the nanodiamond powder has an average particle size less than 100 nanometers (nm).

7. The method of claim 1 , wherein the nanodiamond powder has an average particle size less than 50 nm.PATENTDocket No. IS22.0489-WO-PCT8. The method of claim 1 , wherein the HPHT conditions include a pressure between 4 gigapascal (GPa) and 9 GPa.

9. The method of claim 1 , wherein the HPHT conditions include a temperature between 1000°C and 2500°C.

10. The method of claim 1 , wherein the sintering duration is between 1 minute and 60 minutes.

11. The method of claim 1 , further comprising sonicating at least a first FND and a second FND of the sintered nanodiamond-salt block.

12. The method of claim 1 , further comprising heat treating the FND.

13. The method of claim 1 , wherein the fluid is water.

14. The method of claim 13, wherein dissolving at least a portion of the salt includes dissolving the portion of the salt into solution in the water.

15. The method of claim 1 , wherein the nanodiamond powder includes an irradiated diamond particle.

16. A method of manufacturing fluorescent nanodiamond, the method comprising: adding a fluid source to a nanodiamond powder; sintering the nanodiamond powder under high-pressure high-temperature (HPHT) conditions for a sintering duration to create a sintered nanodiamond block, wherein at least a portion of the fluid source changes to a supercritical fluid at the HPHT conditions;PATENTDocket No. IS22.0489-WO-PCT washing at least a portion of the sintered nanodiamond block with a fluid; and separating a fluorescent nanodiamond from the fluid.

17. The method of claim 16, wherein the fluid source is liquid water.

18. The method of claim 16, wherein the fluid source is wax.

19. The method of claim 16, wherein the supercritical fluid is carbon dioxide.

20. The method of claim 16, wherein the supercritical fluid has a density greater than 1 gram per milliliter (g / ml) at the HPHT conditions.21 . The method of claim 16, wherein the supercritical fluid has a density greater than 1.1 gram per milliliter (g / ml) at the HPHT conditions.

22. The method of claim 16, wherein adding a fluid source to the nanodiamond powder includes mixing the fluid source with the nanodiamond powder.

23. The method of claim 16, wherein adding a fluid source to the nanodiamond powder includes adding a separated layer to the nanodiamond powder.

24. The method of claim 16, further comprising mixing a nanodiamond powder with a salt powder to create a nanodiamond-salt mixture prior to sintering.

25. The method of claim 24, wherein the fluid source is less than 5 percentage by volume (vol%) of a total weight of the nanodiamond-salt mixture and the fluid source.PATENTDocket No. IS22.0489-WO-PCT26. The method of claim 24, wherein the fluid source is no more than 2 percentage by weight (wt%) of a total weight of the nanodiamond-salt mixture and the fluid source.

27. The method of claim 24, wherein a void percentage by volume (vol%) in a sintered block of the nanodiamond-salt mixture and supercritical fluid at the HPHT conditions is no more than 1vol%.

28. The method of claim 27, wherein the nanodiamond-salt mixture is no less than 25% salt by weight.

29. The method of claim 16, wherein separating the fluorescent nanodiamond from the fluid includes removing supernatant nanodiamonds from the fluid.

30. The method of claim 16, wherein the nanodiamond powder includes an irradiated diamond particle.

31. A method of manufacturing fluorescent nanodiamond, the method comprising: mixing a nanodiamond powder with a salt and a fluid source to create a nanodiamond-salt mixture including the fluid source; sintering the nanodiamond-salt mixture under high-pressure high- temperature (HPHT) conditions for a sintering duration to create a sintered nanodiamond-salt block, wherein at least a portion of the fluid source changes to a supercritical fluid at the HPHT conditions; washing at least a portion of the sintered nanodiamond-salt block with a solvent; dissolving at least a portion of the salt from at least one fluorescent nanodiamond (FND) of the sintered nanodiamond-salt block with the solvent; and separating the FND from the salt.

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