A method for preparing single particle samples for three-dimensional nano X-ray imaging

Abstract

The present invention belongs to the field of X-ray imaging technology, and particularly relates to a method for preparing a single-particle sample specifically for three-dimensional nano X-ray imaging. The method comprises: dispersing particles with a size of 10 to 50 μm; screening the particles; processing and preparing a cylinder of a certain diameter as a support rod; preparing a glue solution, placing the glue solution on the top surface of the lowest end of a vertically fixed support rod to form a hemispherical glue droplet; using a thin mirror to determine the height of the lowest point of the hemispherical glue droplet; adjusting the plane position of the particle so that the lowest point of the hemispherical glue droplet contacts the particle, and further lowering the height to increase the bonding volume; raising the support rod, and after the bonding strength reaches maximum, removing the support rod and starting the three-dimensional nano X-ray imaging single-particle sample scan. The present invention overcomes the drawbacks of existing methods such as easy obstruction, high failure rate, expensive equipment, and high technical barriers, and achieves the precise, simple, rapid, and low-cost preparation of samples specifically for three-dimensional X-ray imaging of various metal, ceramic, and composite material particles.

Description

Technical Field

[0001] The present invention belongs to the technical field of X-ray imaging, and in particular relates to a method for preparing a special single particle sample for three-dimensional nano X-ray imaging. Background Art

[0002] The demand for three-dimensional structural detection of particle samples is increasing. Representative application scenarios include additive manufacturing powder quality control, battery positive electrode material particle design, and catalytic particle structure design. The basis of additive manufacturing technology is powder. The quality of powder affects the performance of additive manufacturing products. For example, internal holes or cracks in the powder itself may be inherited into the final additive manufacturing product. The three-dimensional structure of the battery positive electrode material particles determines the availability of the positive electrode material during charging and discharging, which in turn affects the cycle life of the battery. The structure of the catalytic particles directly determines the catalytic efficiency and has always been one of the key research directions in the field of catalysis. However, the size of the particle samples generally ranges from a few microns to hundreds of microns, and most of the size is distributed in tens of microns. Imaging its three-dimensional structure is a difficult problem.

[0003] In recent years, X-ray 3D imaging technology has rapidly developed. It can be used to reveal internal heterogeneity in materials, such as the three-dimensional spatial distribution and quantitative information of pores, cracks, segregation, inclusions, secondary phases, and hierarchical phases, establishing relationships between composition, structure, properties, or service performance. Currently, the spatial resolution of laboratory-based 3D nano X-ray microscopy reaches 50 nanometers, while the spatial resolution of 3D nano X-ray imaging based on synchrotron radiation sources can reach 20-30 nanometers. 3D nano X-ray imaging technology offers opportunities for 3D imaging of granular samples. However, the difficulty of sample preparation has limited the application and widespread adoption of 3D nano X-ray imaging technology. There are only approximately 10 instruments or imaging beamlines in China capable of 3D nano X-ray imaging. The low energy X-rays used in this technology have relatively good penetration for rock samples, but relatively poor penetration for samples containing heavy metals. Samples are typically on the order of 10 microns, and the samples must not exhibit nanometer-scale drift over scanning times of tens of hours. These requirements pose significant challenges to sample preparation. Sample preparation methods such as micron CT and other seemingly similar methods are not suitable for preparing particle samples specifically for 3D nano-X-ray imaging. This is primarily due to two reasons: First, the specific location requirements for sample bonding or fixation vary. Samples may contain multiple particles with inter-particle occlusion, or may contain a single particle obscured by colloids or other objects. In these cases, micron CT testing and certain probe tests are possible, but not 3D nano-X-ray imaging. This obscuration results in low transmittance, severely insufficient photons received by the detector, and incapable of 3D nano-imaging. Second, the required fixation strength varies. Micron CT pixel sizes typically range from a few hundred nanometers to microns. Sample drift of a few hundred nanometers during scanning is negligible, but 3D nano-imaging is impossible. 3D nano-X-ray imaging can achieve pixel sizes up to 16 nanometers, and sample drift during scanning must be controlled to within 10 nanometers. Sample drift of a few hundred nanometers prevents 3D reconstruction from 3D nano-X-ray imaging. Currently, the predominant preparation method utilizes a focused ion beam system equipped with a scanning electron microscope and micro-nanofabrication capabilities. However, this method has many disadvantages, such as poor access to instrument resources, high price, high technical threshold, and complex operation.

[0004] In summary, there is an urgent need to develop a simple method for preparing single-particle samples specifically for three-dimensional nano-X-ray imaging, so that researchers can use existing ordinary laboratory resources to realize the preparation of special samples for three-dimensional nano-X-ray imaging of various particles, meet the requirements of unobstructed three-dimensional nano-imaging of particle samples and dozens of hours of fixed drift-free, obtain more non-uniform structural information inside various particles, and be widely used in various types of metal, ceramic and composite material particle samples. Summary of the Invention

[0005] The purpose of the present invention is to provide a precise, simple and fast method for preparing single-particle samples for three-dimensional nano-X-ray imaging, which can meet the requirements of unobstructed three-dimensional nano-imaging of particle samples and dozens of hours of fixed drift-free imaging, and obtain more heterogeneous structural information inside various particles.

[0006] The technical solution of the present invention is:

[0007] A method for preparing a single particle sample for a three-dimensional nano X-ray microscope comprises the following steps:

[0008] Step 1: Place multiple particles on a flat substrate and apply slight vibration to the substrate to disperse the particles;

[0009] Step 2: Place the substrate under an optical microscope, screen the target particles, and mark around the target particles;

[0010] Step 3: Process and prepare the cylinder. The surfaces of both ends of the cylinder should be flat and the roughness should not exceed 10μm.

[0011] Step 4: Select the cylinder processed in step 3 as the support rod and fix one end of it vertically with a clamp;

[0012] Step 5: Prepare the glue solution, wait 1 to 3 minutes, dip the glue solution, and place it on the top surface of the bottom end of the support rod fixed in step 4 to obtain a hemispherical glue droplet;

[0013] Step 6: Place the substrate with target particles from step 2 on the table below the support rod from step 5;

[0014] Step 7: Select a thin sheet with a mirrored top surface and record the thickness of the sheet as h1;

[0015] Step 8: Place the wafer from step 7 on the particle-free area of the substrate from step 6. Use a micrometer to adjust the wafer's plane position so that it is below the support rod. Using a magnifying glass, adjust the height of the support rod so that the initially solidified hemispherical droplet just touches the mirror surface. Record the Z coordinate of the lowest point of the hemispherical droplet at this time as Z1.

[0016] Step 9: Use a micrometer to measure the particle height, recorded as h2;

[0017] Step 10: Roughly adjust the plane position of the target particle so that it is directly below the support rod. Adjust the Z coordinate of the lowest point of the hemispherical glue droplet to Z1+h1-h2. At this time, the lowest point of the hemispherical glue droplet and the highest point of the target particle are located at the same Z coordinate point;

[0018] Step 11: Raise the support rod, remove the initially solidified hemispherical glue droplet, repeat step 5, and readjust the Z coordinate of the lowest point of the hemispherical glue droplet to Z1+h1-h2;

[0019] Step 12: Under observation with a magnifying glass, finely adjust the plane position of the target particle so that the lowest point of the unsolidified hemispherical glue drop on the top surface of the lower end of the support rod contacts the target particle;

[0020] Step 13: Adjust the lowest point height of the hemispherical glue droplet. According to the size of the particles, continue to lower it to a certain height to increase the contact volume and strengthen the fixing strength.

[0021] Step 14: Raise the support rod, let it stand for a while, then remove the support rod and start 3D nano X-ray imaging single particle sample scanning.

[0022] The top and bottom surfaces of the substrate in step 1 must be flat and parallel to the surface. Particles contain heavy metal elements and are limited to a size of 10 to 50 μm. Dispersed particles do not necessarily mean that all particles are completely dispersed, but rather that a few particles are independently dispersed.

[0023] The optical microscope in step 2 refers to various optical microscopes that can magnify and observe particles.

[0024] In step 3, the diameter of the cylinder is 100 to 600 μm, and the diameter of the cylinder matches the size of the particles.

[0025] The clamp in step 4 can fix the cylinder in step 3 and serve as a clamping device with the length direction of the cylinder perpendicular to the placement table.

[0026] The glue used in step 5 should be one that cures in 5 minutes and reaches full strength in 24 hours. Examples include epoxy AB glue and methyl acrylate AB glue. The hemispherical glue droplet should match the cylinder diameter. The smaller the cylinder diameter, the smaller the hemispherical glue droplet, which is more conducive to precise bonding of small particles.

[0027] The thin sheet in step 7 is made of metal or ceramic, with a thickness ranging from tens of microns to millimeters, and the upper and lower surfaces must be flat and parallel to each other.

[0028] The removal of the glue droplets in step 11 can be carried out by cutting with scissors, soaking in hot water, burning with a lighter, and breaking by hand, or a combination of two or more methods.

[0029] The magnifying glass in step 12 can be used with different magnifications depending on the size of the particles, as long as you can clearly see the particles and their positions. The unsolidified glue droplets are not yet completely solidified and lose their adhesive properties. On the other hand, the glue droplets still have a certain viscosity, which allows them to maintain their hemispherical shape and have a certain degree of adhesion.

[0030] The descent height in step 13 refers to a descent of 2 to 10 μm. The smaller the particle size, the smaller the descent height. For a 50 μm particle, the descent height is approximately 10 μm; for a 10 μm particle, the descent height is approximately 2 μm. After the lowest point of the hemispherical droplet contacts the target particle, continuing to descend by a certain height effectively increases the contact volume between the droplet and the particle, enhancing the droplet's ability to secure the particle.

[0031] The 3D nano-X-ray imaging in step 14 can be performed using nano-CT, a 3D nano-X-ray microscope, or a nano-imaging beamline at a synchrotron radiation source. The reason for the adhesive to stand for a period of time is that the curing strength increases over time. For example, after 2 hours of bonding, the curing strength is approximately 20% of the maximum strength; after 12 hours of bonding, the curing strength is approximately 60%-70% of the maximum strength. After 24-48 hours of standing, the curing strength reaches its maximum value, meeting the requirement for long-term high stability and no drift of the particles.

[0032] The design concept of the present invention:

[0033] like Figure 1 As shown, the present invention aims to develop a simple, low-cost method for preparing single-particle samples specifically for 3D nano-X-ray imaging. This method avoids the use of large, expensive instruments such as focused ion beam systems and utilizes only ordinary laboratory resources to produce samples that meet the requirements of 3D imaging. This method utilizes the fact that an inverted droplet of glue bonded to a flat surface can spontaneously form a hemispherical shape under gravity. Using simple tools such as a micrometer and ingeniously utilizing the principle of a mirror, a single particle is precisely bonded and fixed to the top of the hemisphere. This method meets the requirements of 3D nano-imaging of particle samples with a size of 10 to 50 μm, with unobstructed, strong penetration, and high stability (nanometer-level drift accuracy).

[0034] The advantages and beneficial effects of the present invention are:

[0035] 1. The sample prepared by the present invention is a single-particle sample. On the one hand, the penetrability is guaranteed, and a single particle can be placed alone in the field of view, avoiding the problem of difficulty in penetration caused by mutual obstruction of multiple particles, obstruction of a single particle by glue, or obstruction of a single particle by other objects; on the other hand, the sample can be accurately positioned and has high stability, avoiding drift of the order of 10 nanometers under the influence of various environmental factors, which seriously affects the imaging quality and leads to the problem of inability to reconstruct three-dimensionally.

[0036] 2. The present invention has two characteristics: First, considering that the field of view of three-dimensional nano X-ray imaging is only on the order of 10 microns and the sample position needs to be precisely controlled, it is necessary to relatively strictly match the sizes of the support rod cylinder, hemispherical glue droplets and particles. Small particles correspond to small-diameter cylinders and small hemispherical glue droplets. The smaller the cylinder diameter, the smaller the hemispherical glue droplets obtained, which is more conducive to precise bonding of small particles; second, an innovative design of the bonding method is made, which not only uses a micrometer, a mirror, and a hemispherical glue droplet to achieve precise and unobstructed bonding of particles, but also, on this basis, further increases the bonding volume and improves the stability of the particles, so that long-term scanning of particles can be achieved to obtain high-quality three-dimensional nano imaging data.

[0037] 3. The present invention overcomes the drawbacks of existing methods, for example, ordinary bonding methods easily block target particles, resulting in impenetrable conditions, a high failure rate, or insufficient bonding strength, and particles easily drift due to environmental interference, which seriously affects imaging quality and three-dimensional data reconstruction. The most suitable focused ion beam equipment has obvious disadvantages, such as high price, the need for professional personnel to use and maintain, limited machine time, and low availability. The present invention can complete sample preparation using only ordinary laboratory resources, without the need for automated control tools and special preparation devices. The tools used, such as micrometers, are tools that are commonly found in ordinary laboratories. The entire sample preparation method not only meets the requirements of unobstructed and high stability, but is also simple, fast, low-cost, easy to learn, and easy to promote. It can be widely used in particle samples of various metals, ceramics, and composite materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Schematic diagram of the tools used in the single-particle sample preparation method for 3D nanoscale X-ray imaging. Reference symbols in the figure: 1 - optical microscope; 2 - table; 3 - X-micrometer; 4 - Y-micrometer; 5 - Z-micrometer; 6 - fixture; 7 - cylinder; 8 - magnifying glass.

[0039] Figure 2 Schematic diagram of using a clamp to vertically fix the cylinder.

[0040] Figure 3 Schematic diagram of the X-direction micrometer, Y-direction micrometer, and table assembly.

[0041] Figure 4 Schematic diagram of a hemispherical glue droplet.

[0042] Figure 5 (a)-(b) are schematic diagrams (a) and actual sample images (b) of a nearly spherical three-dimensional nano X-ray imaging single particle sample; Figure 5 (c)-(d) are a schematic diagram of an irregularly shaped three-dimensional nano X-ray imaging single particle sample (c) and an actual sample image (d). DETAILED DESCRIPTION

[0043] In the specific implementation process, the present invention provides a method for preparing a single-particle sample specifically for three-dimensional nano-X-ray imaging, including: dispersing particles with a size of 10 to 50 μm; screening the particles; processing and preparing a cylinder of a certain diameter as a support rod; preparing a glue solution, and placing the glue solution on the top surface of the lower end of a vertically fixed support rod to form a hemispherical glue droplet; using a thin film mirror to determine the height of the lowest point of the hemispherical glue droplet; adjusting the plane position of the particle so that the lowest point of the hemispherical glue droplet contacts the particle, continuing to lower the height and increasing the bonding volume; raising the support rod, and after the bonding strength reaches the maximum, removing the support rod and starting the three-dimensional nano-X-ray imaging single-particle sample scanning.

[0044] like Figure 1 As shown, the tools used in the method for preparing a single particle sample for three-dimensional nano X-ray imaging of the present invention mainly include: an optical microscope 1, a table 2, an X-direction micrometer 3, a Y-direction micrometer 4, a Z-direction micrometer 5, a fixture 6, a cylinder 7, and a magnifying glass 8. The specific structure and composition are as follows:

[0045] A horizontal table 2 is used to place a substrate with target particles. A clamp 6 is used to clamp a cylinder 7 with a fixed length perpendicular to the table 2 above the table 2. An optical microscope 1 is used to screen the particles, and a magnifying glass 8 is used to adjust the height of the cylinder 7. An X-direction micrometer 3 is set on the X-direction side of the table 2, a Y-direction micrometer 4 is set on the Y-direction side of the table 2, and a Z-direction micrometer 5 is set on the Z-direction of the table 2.

[0046] Use Figure 1 The specific preparation steps for the tool shown are as follows:

[0047] Step 1: Place multiple particles on a flat substrate and apply slight vibration to the substrate to disperse the particles. The upper and lower surfaces of the substrate are required to be flat and parallel to the table 2 on which it is placed. The color of the substrate is preferably selected to have a large contrast with the color of the particles, such as: if the particles are black, the substrate color is white; if the particles are white, the substrate color is black, so that the particles are easy to distinguish. Particles refer to particles containing heavy metal elements, and the size range is limited to 10 to 50 μm. The dispersion of particles does not mean that all particles are completely dispersed, but that several (preferably 1 to 10) particles are in an independently dispersed state.

[0048] Step 2: Place the substrate under an optical microscope (1), screen for target particles, and mark the area around them. The optical microscope (1) should be sufficient to magnify, locate, and observe the particles. To mark the particles, use a colored marker, pencil, fountain pen, or ballpoint pen to circle the particles. Alternatively, draw a short line or dot next to the particles.

[0049] Step 3: Process and prepare a cylinder 7 with a diameter of 100 to 600 μm. The surfaces of both ends of the cylinder 7 must be flat with a roughness not exceeding 10 μm. The cylinder 7 can be made of metal, ceramic, polymer or composite material.

[0050] Step 4: If Figure 2 As shown, the cylinder 7 processed in step 3 is selected as the support rod, and one end of the cylinder 7 is fixed vertically with a clamp 6, so that the clamp 6 is on top and the support rod is on the bottom. The clamp 6 can fix the cylinder 7 in step 3 and serve as a clamping device to ensure that the length direction of the cylinder 7 is perpendicular to the placement table 2.

[0051] Step 5: Prepare the glue and wait for 1 to 3 minutes; if the amount of glue prepared is large, its curing rate is relatively fast, and you can wait for 1 minute; if the amount of glue prepared is small, its curing rate is relatively slow, and you can wait for 3 minutes; then dip the glue and place it on the top surface of the lower end of the support rod fixed in step 4.

[0052] The requirements for large-area bonding in the existing technology are low, and general glue can be used to achieve it. However, for three-dimensional nano-imaging, the smaller the area, the smaller the contact area is in the square order of magnitude, the more difficult the bonding is, and the greater the strength requirement for the glue after solidification. The glue used here refers to a glue that meets the initial curing requirements of 5 minutes and can basically reach the maximum strength in 24 hours. For example: epoxy resin AB glue and methyl acrylate AB glue, etc. For particles with a size of 10 to 50 μm, it is necessary to control the particles after bonding so that they cannot sink into the glue as a whole, nor can they slide to one side of the glue. After curing, they must maintain high stability and no drift of more than 10 nanometers will occur within dozens of hours (preferably 72 hours) and under the influence of various environmental factors such as external vibration, sample translation, sample rotation, and temperature fluctuation. Therefore, during the bonding process, there are requirements for the curing state, placement position, and placement direction of the glue. For example, when the glue is first prepared, it is highly fluid and gradually solidifies over time. When the degree of solidification is low, the viscosity is low, which can easily cause the particles to be bonded to sink into the glue or shift. When the glue is placed on the side or top surface of the support rod, it can easily spread along the support rod, making it more difficult for the particles to bond and increasing the possibility of obstruction. Therefore, the present invention sets the rest time to 1 to 3 minutes, which is conducive to reducing the fluidity of the glue droplets to a suitable state. Figure 4 As shown, when the glue is placed on the top surface of the lower end of the support rod, combined with the gravity of the glue, the glue droplets will spontaneously form a hemispherical shape, providing excellent position conditions for the subsequent bonding of particles.

[0053] Step 6: Place the substrate with target particles from step 2 on table 2 below the support rod from step 5.

[0054] Step 7: Select a thin sheet, which can be made of ceramic, titanium alloy, zirconium alloy, aluminum alloy, magnesium alloy or steel, with a thickness of tens of microns to millimeters (preferably 100-1000 microns). Use grinding and polishing technology to grind both sides of the sheet flat, with the upper and lower surfaces parallel, and polish the upper surface to a mirror finish. Record the thickness of the sheet as h1.

[0055] Step 8: Place the sheet from step 7 on the particle-free area of the substrate from step 6. Use a micrometer to adjust the plane position of the sheet so that it is located below the support rod. With the help of a magnifying glass 8, adjust the height of the support rod so that the hemispherical glue drop that has been initially solidified just touches the mirror surface. Record the Z coordinate of the lowest point of the hemispherical glue drop at this time as Z1. Figure 1 As shown in the figure, in actual operation, the height of the support rod is adjusted using a micrometer. The Z coordinate is mapped to the micrometer reading, and the coordinate position of the hemispherical glue drop in the Z direction is adjusted by increasing or decreasing the micrometer reading. For example, if the hemispherical glue drop needs to be lowered by a height a based on Z1, then the micrometer reading can be adjusted to Z1 + a. The micrometer will then drive the hemispherical glue drop on the top surface of the bottom end of the support rod to drop by a height a.

[0056] Step 9: Use a micrometer to measure the height of the particle on the substrate, recorded as h2.

[0057] Step 10: Figure 3 As shown, use a micrometer to roughly adjust the plane position of the target particle so that it is directly below the support rod, and adjust the Z-direction coordinate of the lowest point of the hemispherical glue droplet to Z1+h1-h2; at this time, the lowest point of the hemispherical glue droplet and the highest point of the target particle are located at the same Z-direction coordinate point.

[0058] Step 11: Raise the support rod and remove the initially solidified hemispherical droplet. This can be done by cutting with scissors, soaking in hot water, burning with a lighter, or manually breaking it apart, or by a combination of these methods. Repeat step 5 and readjust the Z coordinate of the lowest point of the hemispherical droplet to Z1+h1-h2.

[0059] Step 12: Under magnifying glass 8, use a micrometer to finely adjust the planar position of the target particle so that the lowest point of the unsolidified hemispherical droplet on the lower surface of the support rod contacts the target particle. The unsolidified droplet refers to the fact that, on the one hand, the droplet has not completely solidified and has lost its adhesive strength, but on the other hand, it still has a certain viscosity, which allows it to maintain its hemispherical shape and possess a certain degree of adhesive strength.

[0060] Step 13: Adjust the lowest point height of the hemispherical glue droplet by further decreasing it by 2 to 10 μm, depending on the particle size, to increase the contact volume and strengthen the fixation strength. A further preferred method is to decrease the lowest point height by 2 μm when the particle size is 10 μm and by 10 μm when the particle size is 50 μm.

[0061] Step 14: Raise the support rod. Under the influence of gravity and adhesive forces, the particles, adhesive, and support rod gradually stabilize in their positions. The adhesive is then allowed to stand for a period of time. The curing strength of the adhesive increases over time. For example, after 2 hours of bonding, the curing strength is approximately 20% of the maximum strength; after 12 hours, the curing strength is approximately 60%-70% of the maximum strength. After 24-48 hours of standing, the curing strength reaches its maximum value, meeting the requirement for long-term high stability and no drift of the particles. The smaller the particle size, the longer the standing time should be. For example, for 50μm particles, the standing time is 24 hours, while for 10μm particles, the standing time is 48 hours to ensure that the curing strength reaches its maximum value. Finally, remove the support rod and begin 3D nano-X-ray imaging of the single particle sample. 3D nano-X-ray imaging can be performed using nano-CT, 3D nano-X-ray microscopy, or a nano-imaging beamline at a synchrotron radiation source. 3D nano-X-ray imaging utilizes differences in X-ray absorption contrast or phase contrast between different regions to achieve non-destructive 3D imaging of the sample's internal microstructure. During the experiment, X-rays are focused by a focusing mirror, pass through the sample, amplified by a zone plate, and received by a detector. The sample is rotated 180 degrees, and simultaneously, 1,000 X-ray projections are collected, each of which is similar to a chest X-ray taken during a hospital physical. Three-dimensional mathematical reconstruction algorithms are then used to obtain absorption contrast information about the sample's internal microstructure. A phase ring is added between the zone plate and the detector to achieve three-dimensional phase contrast imaging of the sample's internal microstructure. The maximum individual voxel size is 7 to 16 nanometers, with a maximum spatial resolution of 20 to 50 nanometers. This places stringent demands on the sample: within the field of view, target particles with micron-sized dimensions in the X, Y, and Z directions must not be obstructed by other particles or objects, thereby ensuring X-ray penetration into the sample. High bonding strength ensures that sample drift caused by external vibrations, sample stage translation, sample stage rotation, and temperature fluctuations within the device cavity is controlled to the nanometer level within a scan time of tens of hours (preferably 72 hours). In conventional characterization, such as scanning electron microscopy or metallographic microscopy samples, there are no high requirements for fixation strength and long-term stability. Only slight fixation is required to meet the requirements of planar observation for a few minutes.

[0062] The following are preferred embodiments of the present invention. It should be understood that the preferred embodiments described herein are merely preferred solutions of the present invention and can be used to explain the present invention, but are not intended to limit the present invention.

[0063] Example 1:

[0064] In this example, Ti6Al4V powder for additive manufacturing was selected to prepare a 3D nano X-ray imaging sample. The steps are as follows:

[0065] Step 1: Place multiple powders on a flat substrate and apply slight vibration to the substrate to disperse the powders;

[0066] Step 2: Place the substrate under an optical microscope, screen the target powder with a size of about 25 μm, and mark around the target powder;

[0067] Step 3: Process and prepare an AZ31 cylinder with a diameter of about 300 μm. The surfaces of both ends of the cylinder should be flat and the roughness should not exceed 8 μm.

[0068] Step 4: Select the cylinder processed in step 3 as the support rod and fix one end of it vertically with a clamp;

[0069] Step 5: Select epoxy resin AB glue, prepare the glue solution, wait for 3 minutes, dip the glue solution, and place it on the top surface of the bottom end of the support rod fixed in step 4 to obtain a hemispherical glue drop;

[0070] Step 6: Place the substrate with the target powder from step 2 on the table below the support rod from step 5;

[0071] Step 7: Select a titanium alloy sheet and use metallographic grinding and polishing technology to grind both sides of the titanium alloy sheet flat, making the upper and lower surfaces parallel, and polish the upper surface to a mirror finish. Record the thickness of the titanium alloy sheet as 600 μm.

[0072] Step 8: Place the titanium alloy sheet from step 7 on the powder-free area of the substrate from step 6. Use a micrometer to adjust the plane position of the titanium alloy sheet so that it is located below the support rod. With the help of a magnifying glass, adjust the height of the support rod so that the initially solidified hemispherical glue droplet just touches the mirror surface. Record the Z coordinate of the lowest point of the hemispherical glue droplet at this time as 300μm.

[0073] Step 9: Use a micrometer to measure the powder height, which is 20 μm.

[0074] Step 10: Roughly adjust the plane position of the target powder so that it is directly below the support rod. Adjust the Z coordinate of the lowest point of the hemispherical glue droplet to 600 + 300 - 20 = 880 μm. At this point, the lowest point of the hemispherical glue droplet and the highest point of the target powder are located at the same Z coordinate point.

[0075] Step 11: Raise the support rod, remove the initially solidified hemispherical glue droplet, repeat step 5, and readjust the Z-direction coordinate of the lowest point of the hemispherical glue droplet to 880 μm;

[0076] Step 12: Under the observation of a magnifying glass, finely adjust the plane position of the target powder so that the lowest point of the unsolidified hemispherical droplet on the lower surface of the support rod contacts the target powder;

[0077] Step 13: Adjust the lowest point height of the hemispherical glue droplet and continue to lower it by 4μm according to the size of the powder to increase the contact volume and strengthen the fixing strength.

[0078] Step 14: Raise the support rod, let it stand for 36 hours, remove the support rod, and start 3D nano X-ray imaging single powder sample scanning.

[0079] Example 2:

[0080] In this example, LiFePO4 positive electrode material particles are selected to prepare a three-dimensional nano X-ray imaging sample, and the steps are as follows:

[0081] Step 1: Place multiple particles on a flat substrate and apply slight vibration to the substrate to disperse the particles;

[0082] Step 2: Place the substrate under an optical microscope, screen target particles with a size of approximately 45 μm, and mark the area around the target particles.

[0083] Step 3: Process and prepare a TC4 cylinder with a diameter of about 500 μm. The surfaces of both ends of the cylinder should be flat and the roughness should not exceed 8 μm.

[0084] Step 4: Select the cylinder processed in step 3 as the support rod and fix one end of it vertically with a clamp;

[0085] Step 5: Select acrylic AB glue, prepare the glue solution, wait for 1 minute, dip the glue solution, and place it on the top surface of the bottom end of the support rod fixed in step 4 to obtain a hemispherical glue drop;

[0086] Step 6: Place the substrate with target particles from step 2 on the table below the support rod from step 5;

[0087] Step 7: Select a magnesium alloy sheet and use metallographic grinding and polishing technology to grind both sides of the magnesium alloy sheet flat, making the upper and lower surfaces parallel, and polish the upper surface to a mirror finish. Record the thickness of the magnesium alloy sheet as 800 μm.

[0088] Step 8: Place the magnesium alloy sheet from step 7 onto the particle-free area of the substrate from step 6. Use a micrometer to adjust the plane position of the magnesium alloy sheet so that it is located below the support rod. With the help of a magnifying glass, adjust the height of the support rod so that the initially solidified hemispherical glue droplet just touches the mirror surface. Record the Z coordinate of the lowest point of the hemispherical glue droplet at this time as 100 μm.

[0089] Step 9: Use a micrometer to measure the particle height, which is 40 μm.

[0090] Step 10: Roughly adjust the plane position of the target particle so that it is directly below the support rod. Adjust the Z coordinate of the lowest point of the hemispherical glue droplet to 800 + 100 - 40 = 860 μm. At this point, the lowest point of the hemispherical glue droplet and the highest point of the target particle are located at the same Z coordinate point.

[0091] Step 11: Raise the support rod, remove the initially solidified hemispherical glue droplet, repeat step 5, and readjust the Z-direction coordinate of the lowest point of the hemispherical glue droplet to 860 μm;

[0092] Step 12: Under observation with a magnifying glass, finely adjust the plane position of the target particle so that the lowest point of the unsolidified hemispherical glue drop on the lower surface of the support rod contacts the target particle;

[0093] Step 13: Adjust the lowest point height of the hemispherical glue droplet and continue to lower it by 8μm according to the particle size to increase the contact volume and strengthen the fixing strength.

[0094] Step 14: Raise the support rod, let it stand for 28 hours, remove the support rod, and start 3D nano X-ray imaging single particle sample scanning.

[0095] like Figure 5 As shown, the results of the embodiments show that the present invention overcomes the shortcomings of the existing technical means such as easy obstruction, high failure rate, expensive instruments, poor resource acquisition, high technical threshold, and complex operation, and innovatively realizes the use of ordinary laboratory resources to complete the accurate, simple, fast, and low-cost preparation of single-particle samples for three-dimensional nano X-ray imaging with a size of 10 to 50 μm, providing a convenient and effective sample preparation method for obtaining three-dimensional non-uniform structural information inside various metal, ceramic and composite material particle samples.

Claims

1. A method for preparing a single particle sample for three-dimensional nano X-ray imaging, characterized in that: The steps include: Step 1: Place multiple particles on a flat substrate and apply slight vibration to the substrate to disperse the particles; Step 2: Place the substrate under an optical microscope, screen the target particles, and mark around the target particles; Step 3: Process and prepare a cylinder. The surfaces of both ends of the cylinder must be flat, with a roughness not exceeding 10 μm. The diameter of the cylinder is 100 to 600 μm, and the size of the particles is limited to 10 to 50 μm. The diameter of the cylinder, the size of the hemispherical droplet, and the size of the particles must match. Step 4: Select the cylinder processed in step 3 as the support rod, fix one end of it vertically with a clamp, and use it as a clamping device so that the length direction of the cylinder is perpendicular to the placement table; Step 5: Prepare the glue solution, wait 1 to 3 minutes, dip the glue solution, and place it on the top surface of the bottom end of the support rod fixed in step 4 to obtain a hemispherical glue droplet; Step 6: Place the substrate with target particles from step 2 on the table below the support rod from step 5; Step 7: Select a thin sheet with a mirrored top surface and record the thickness of the sheet as h1; Step 8: Place the wafer from step 7 on the particle-free area of the substrate from step 6. Use a micrometer to adjust the wafer's plane position so that it is below the support rod. Using a magnifying glass, adjust the height of the support rod so that the initially solidified hemispherical droplet just touches the mirror surface. Record the Z coordinate of the lowest point of the hemispherical droplet at this time as Z1. Step 9: Use a micrometer to measure the particle height, recorded as h2; Step 10: Roughly adjust the plane position of the target particle so that it is directly below the support rod. Adjust the Z coordinate of the lowest point of the hemispherical glue droplet to Z1+h1-h2. At this time, the lowest point of the hemispherical glue droplet and the highest point of the target particle are located at the same Z coordinate point. Step 11: Raise the support rod, remove the initially solidified hemispherical glue droplet, repeat step 5, and readjust the Z coordinate of the lowest point of the hemispherical glue droplet to Z1+h1-h2; Step 12: Under observation with a magnifying glass, finely adjust the plane position of the target particle so that the lowest point of the unsolidified hemispherical glue drop on the top surface of the lower end of the support rod contacts the target particle; Step 13: Adjust the lowest point height of the hemispherical glue droplet and continue to lower it by 2 to 10 μm according to the particle size to increase the contact volume and strengthen the fixing strength. Step 14: Raise the support rod, let it stand for a while, then remove the support rod and start 3D nano X-ray imaging single particle sample scanning.

2. The method according to claim 1, characterized in that The bonding of large-sized particles corresponds to large-diameter cylinders and large hemispherical droplets, while the bonding of small-sized particles corresponds to small-diameter cylinders and small hemispherical droplets.

3. The method according to claim 1, characterized in that The particles in step 1 are particles containing heavy metal elements.

4. The method according to claim 1, wherein The particles in step 1 are dispersed, which does not mean that all particles are completely dispersed, but that several particles are in an independently dispersed state.

5. The method according to claim 1, characterized in that The glue used in step 5 is one that can initially cure in 5 minutes and reach maximum strength in 24 hours.

6. The method according to claim 1, characterized in that The thin sheet in step 7 is made of metal or ceramic, with a thickness ranging from tens of microns to millimeters, and the upper and lower surfaces must be flat and parallel to each other.

7. The method according to claim 1, characterized in that The upper and lower surfaces of the substrate in step 1 must be flat and parallel to the placement table.

8. The method according to claim 1, characterized in that The three-dimensional nano X-ray imaging in step 14 uses a nano CT, a three-dimensional nano X-ray microscope or a nano imaging beamline of a synchrotron radiation light source.

Images