A method for preparing a transmission electron microscope sample of magnetic powder particles

Abstract

A method for preparing a transmission electron microscope sample of magnetic powder particles belongs to the technical field of transmission electron microscope sample preparation, and comprises the following steps: embedding magnetic powder particles in a transmission electron microscope sample support net, further fixing them with a special resin for ion thinning, respectively arranging thin film materials on the upper and lower layers, applying pressure with a clamp, making the special resin for ion thinning evenly distributed, completely wrapping the transmission electron microscope sample support net and the magnetic powder particles, exhausting the existing air, heating and heat preservation and then cooling, taking out the support net, preparing a thin area, and obtaining a transmission electron microscope sample of magnetic powder particles. The present invention can make the magnetic powder particles be subjected to transmission electron microscope microstructure observation, ensure that the magnetic powder particles can be stable and immobile under high-intensity magnetic field conditions, and make transmission electron microscope observation of the microstructure of the magnetic powder particles possible.

Description

Technical Field

[0001] The invention belongs to the technical field of transmission electron microscope sample preparation, and particularly relates to a method for preparing a magnetic powder particle transmission electron microscope sample. Background Art

[0002] The preparation of existing powdered TEM samples first requires mixing the powder with a special resin for ion thinning of TEM samples and curing it into a shape, then using a cutting device to cut it into thin slices and process it into discs, and finally preparing the thin area required for TEM observation by ion thinning. This method cannot guarantee that the cut slices are thin enough, and a long mechanical thinning process is required. At the same time, due to the presence of powder particles, there is a significant difference in hardness between the powder particles and the special resin for ion thinning of TEM, which will cause the resin to soften and deform during the cutting process, making the thickness of the resin sheet uneven. At the same time, it cannot be guaranteed that the powder particles are effectively cut. Since the particles cannot be effectively cut and the thickness of the resin sample sheet cannot be thin enough, it cannot be guaranteed that the powder particles can be effectively thinned in the final ion thinning process. As a result, the electron beam cannot penetrate the powder particles, a clear transmission electron image cannot be obtained, and research characterization methods such as electron beam diffraction cannot be performed. In the process of mixing the resin and powder particles, all air cannot be discharged. During the heating and curing process, these air will gather on the surface of the resin and powder particles to form bubbles. Therefore, there will be a large number of bubbles in the cured resin block, especially on the surface of the powder particles. The presence of bubbles reduces the degree of resin wrapping of powder particles. During transmission electron microscopy observation, powder particles will move or even fall off due to high magnetic field intensity and incomplete resin wrapping. Or the surface tension of the film on the transmission electron microscope sample support net is used to adsorb magnetic powder particles. However, this method cannot effectively restrain magnetic powder particles. Under the action of the strong magnetic field in the transmission electron microscope sample chamber, magnetic powder particles are easy to move or fall off. Moreover, the magnetic powder particles are not thinned, and the electron beam cannot penetrate the particles. In summary, the efficiency of preparing powder particle transmission electron microscope samples using traditional process methods is relatively low, the preparation cycle is long, and the effect is not good, which seriously restricts the observation and research of the microstructure characteristics of powder particle samples. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a method for preparing a transmission electron microscope sample of magnetic powder particles, which can effectively solve the problems of thickness of the transmission electron microscope sample of magnetic powder particles and cutting of powder particles.

[0004] The technical solution adopted by the present invention is as follows:

[0005] A method for preparing a transmission electron microscope sample of magnetic powder particles comprises the following steps: embedding magnetic powder particles in a transmission electron microscope sample support net, further fixing them with a special resin for ion thinning, arranging thin film materials on the upper and lower layers respectively, applying pressure with a clamp to make the special resin for ion thinning evenly distributed and completely wrap the transmission electron microscope sample support net and the magnetic powder particles, exhausting the existing air, heating and heat preservation and then cooling, taking out the support net, preparing a thin area, and obtaining a transmission electron microscope sample of magnetic powder particles.

[0006] Furthermore, the film is a metal film, specifically aluminum foil.

[0007] Furthermore, the clamp includes an upper fixing plate, a lower fixing plate, bolts and a pressure block. Four bolt holes are equidistantly provided at corresponding positions of the upper fixing plate and the lower fixing plate. Bolts are provided in the bolt holes. The upper fixing plate and the lower fixing plate of the clamp are adjusted by bolts. The pressure block is placed between the upper fixing plate and the lower fixing plate of the clamp.

[0008] Furthermore, the specific steps are as follows: (1) placing a metal block with a smooth surface on the bottom layer; (2) laying a layer of aluminum foil on the metal block, and placing a number of transmission electron microscope sample holders on the aluminum foil; (3) evenly laying a layer of magnetic powder particles on the transmission electron microscope sample holder, and then dripping a special resin for ion thinning of transmission electron microscope samples; (4) covering the upper layer of the resin with aluminum foil to make a thin sheet with aluminum foil wrapped on both the top and the bottom; (5) placing a metal block with a smooth surface on the upper layer of the aluminum foil, with an aluminum foil sheet between the two metal blocks, and with a transmission electron microscope sample holder, magnetic powder particles and the like in the middle of the aluminum foil sheet. (6) using a clamp to clamp two metal blocks containing aluminum foil, and applying force evenly to the metal blocks, so that the magnetic powder particles are embedded in the holes of the transmission electron microscope sample support net; (7) placing the clamp with the aluminum foil in a heating furnace for heating and keeping warm; (8) after cooling down, taking out the aluminum foil, and using a carving knife to take out the transmission electron microscope sample support net according to the contour of the transmission electron microscope sample support net; (9) using an ion thinning instrument to bombard the aluminum foil transmission electron microscope sample surface at a large angle, so that the magnetic powder particles are thinned, and a magnetic powder particle transmission electron microscope sample is obtained.

[0009] The present invention solves the problem of forming and cutting magnetic powder particle transmission electron microscope samples. It overcomes the problem of deformation of resin samples during cutting, ensures the thickness of transmission electron microscope samples, and enables magnetic powder particles to be effectively thinned. It reduces the air in the sample, enables transmission electron microscope ion thinning resin and magnetic powder particles to fully contact and completely wrap the magnetic powder particle sample. In the traditional powder particle transmission electron microscope sample preparation process, the uniform distribution of powder particles cannot be guaranteed, which affects the efficiency of powder particle transmission electron microscope sample preparation.

[0010] The advantages and effects of the present invention are:

[0011] 1. Sheet-shaped transmission electron microscope samples can be directly prepared. While ensuring the thickness of the sample, the sample cutting process is avoided; 2. Due to the different hardness of the special resin for ion thinning and the powder particles, the special resin for ion thinning may produce a rough surface during the cutting process, and the powder particles are not effectively cut, which affects the subsequent ion thinning effect. At the same time, the surface of the special resin for ion thinning is not easy to process smooth. The use of the new process involved in the patent of this invention can effectively avoid the above problems; 3. Ensure that the magnetic powder particles can be fully wrapped by the special resin for ion thinning, reduce the air content in the special resin sample for ion thinning, and enable the magnetic powder particles to be doubly fixed by the special resin for ion thinning and the transmission electron microscope sample support. There is a high-intensity magnetic field in the transmission electron microscope sample chamber. Under the fixation of the special resin for ion thinning and the transmission electron microscope sample holder, the magnetic powder particles can overcome the effect of the magnetic field and ensure that the position of the magnetic powder particles remains unchanged; Fourth, during the ion thinning process, the thinning area can be determined, which is beneficial to the thinning and observation of the magnetic powder particles; Fifth, the new process can increase the distribution density of magnetic powder particles in the transmission electron microscope sample holder, increase the probability of effective thinning of magnetic powder particles, and improve the preparation efficiency of magnetic powder particle transmission electron microscope samples.

[0012] The present invention has the advantages of high efficiency and speed, can ensure the firm fixation of magnetic powder particles and the thickness of transmission electron microscope samples, the magnetic powder particles are fully ion-thinned, no additional sample cutting steps are required, the consumption of special resin for ion thinning is low, and the air content in the sample is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 3D schematic diagram of the transmission electron microscope sample preparation device for magnetic powder particles of the present invention;

[0014] Figure 2 This is a 3D axial view of the transmission electron microscope sample preparation device for magnetic powder particles of the present invention;

[0015] Figure 3 It is a schematic diagram of a transmission electron microscope sample preparation device for magnetic powder particles of the present invention;

[0016] Figure 4 It is a schematic diagram of the assembly of the transmission electron microscope sample preparation device of magnetic powder particles of the present invention;

[0017] Figure 5 It is a bottom view of the transmission electron microscope sample preparation device of magnetic powder particles of the present invention;

[0018] Figure 6 This is a schematic diagram of the structure of a pressure block in the magnetic powder particle transmission electron microscope sample preparation device of the present invention;

[0019] Figure 7 It is a schematic diagram of the upper and lower fixing plates of the fixture in the transmission electron microscope sample preparation device of the magnetic powder particles of the present invention. DETAILED DESCRIPTION

[0020] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0021] The present invention is a method for preparing a transmission electron microscope sample of magnetic powder particles, comprising a transmission electron microscope sample support net, a special resin for ion thinning, aluminum foil (metal foil of other materials, such as tantalum foil, etc.), a pressurizing device, a heating furnace, and a special device for ion thinning. The method is to embed magnetic powder particles in the transmission electron microscope sample support net, and further fix them with the special resin for ion thinning. The fixing method of magnetic powder particles is different from that of traditional powder particle transmission electron microscope samples. The special resin for ion thinning is evenly distributed by applying pressure, completely wrapping the transmission electron microscope sample support net, and exhausting the existing air.

[0022] The main structure is as follows: (1) Place a flat metal block at the bottom layer to ensure that the surface of the metal block is flat: (2) Place a layer of aluminum foil on the metal block, and place multiple transmission electron microscope sample holders on the aluminum foil; (3) Evenly spread a layer of magnetic powder particles on the transmission electron microscope sample holder, and then drip a special resin for ion thinning of transmission electron microscope samples; (4) Cover the upper layer of the resin with aluminum foil to make a thin sheet with aluminum foil wrapped on both the top and the bottom; (5) Place a metal block with a flat surface on the upper layer of the aluminum foil. In the middle of the two metal blocks is an aluminum foil sheet, and in the middle of the aluminum foil sheet are transmission electron microscope sample holders, magnetic powder particles, and transmission electron microscope sample ion thinning resin. Form an object similar to a sandwich structure; (6) Use a specially designed clamp to clamp the two metal blocks containing aluminum foil. Use bolts in four directions to apply pressure so that the metal block is evenly stressed and the force is transmitted to the aluminum foil, so that the magnetic powder particles can be embedded in the holes of the TEM sample holder. (7) Put the special fixture with the aluminum foil into the heating furnace to heat and keep it warm. (8) After cooling down, take out the aluminum foil and use a carving knife to take out the TEM sample holder according to the outline of the TEM sample holder. (9) Use a special ion thinning device to bombard the sample surface to thin the magnetic powder particles for easy observation under the TEM. The position relationship of all components is up and down. Stack and rise layer by layer.

[0023] The present invention spreads magnetic powder particles on the transmission electron microscope sample support net, and uses the transmission electron microscope special ion thinning resin and stress to embed the magnetic powder particles in the holes of the transmission electron microscope sample support net. The upper and lower layers of aluminum foil on the transmission electron microscope sample support net ensure the integrity of the transmission electron microscope sample. Figure 1-Figure 7The special fixture shown applies pressure to the aluminum foil to ensure that the aluminum foil is evenly stressed. Finally, the aluminum foil TEM sample is bombarded at a large angle using an ion thinning instrument to prepare a thin area. This method ensures that the magnetic powder particles are distributed in the TEM observation area and that the magnetic powder particles can be fully thinned by ions. It ensures that the high-intensity magnetic field in the TEM sample chamber does not move the magnetic powder particles.

[0024] The present invention uses a film material (metal foil) such as aluminum foil to wrap a magnetic powder particle transmission electron microscope sample. The magnetic powder transmission electron microscope sample special fixture device is provided with four screw holes around it, and the diameter of the screw hole circle is 4.5 mm. The compressive stress can be uniformly applied by the bolts, so that the stress is transmitted to the magnetic powder particles, so that the magnetic powder particles can be embedded in the holes of the transmission electron microscope sample support net.

[0025] Embodiment 1:

[0026] like Figure 1-Figure 7 As shown, the clamp comprises a clamp upper fixing plate 1, a clamp lower fixing plate 2, a bolt 3 and a pressure block 4. The clamp upper fixing plate 1 and the clamp lower fixing plate 2 are square plates with a side length of 50mm and a thickness of 3mm, and arcs with a radius of 5 are formed at the four corners. Four bolt holes with a hole diameter of 4.5mm are equidistantly opened at the corresponding positions 10mm away from the central axis, and bolts 3 are arranged in the bolt holes. The clamp upper fixing plate 1 and the clamp lower fixing plate 2 are adjusted by bolts 3. The pressure block 4 is placed between the clamp upper fixing plate 1 and the clamp lower fixing plate 2, and the pressure block is a square block with a side length of 16mm and a thickness of 4mm.

[0027] The magnetic powder particles are spread on the transmission electron microscope sample support net and a special resin for ion thinning of the transmission electron microscope is added. The special resin for ion thinning is M-BOND 610 special resin for ion thinning. Pressure is applied so that the special resin for ion thinning can fully wrap the magnetic powder particles and embed the magnetic powder particles into the holes of the transmission electron microscope sample support net. Under the action of aluminum foil, a thin sheet sample is formed so that the special resin for ion thinning of the transmission electron microscope sample does not overflow. At this time, the special heating fixture can solidify the special resin for ion thinning of the transmission electron microscope sample. Since the holes of the transmission electron microscope sample support net also play a fixing role, the magnetic powder particles are not affected by the strong magnetic field in the transmission electron microscope sample chamber. The transmission electron microscope sample support net is removed according to the outline of the transmission electron microscope sample support net. The thin area required for transmission electron microscope observation is prepared by the ion thinning method.

[0028] The present invention can directly prepare a sheet-like transmission electron microscope sample, avoid the sample cutting process, improve the preparation efficiency of the magnetic powder particle transmission electron microscope sample, and save the special resin for ion thinning of the transmission electron microscope sample. The preparation process of the magnetic powder particle transmission electron microscope sample is simplified, and the problem of uneven surface caused by the cutting process of the traditional magnetic powder particle transmission electron microscope sample is overcome.

[0029] The present invention selects a transmission electron microscope sample support net with suitable aperture and hole shape, embeds magnetic powder particles in the transmission electron microscope sample support net, wraps it with aluminum foil and adds special resin for ion thinning. A specially designed fixture is used to squeeze the aluminum foil up and down, so that the special resin for ion thinning can completely cover the transmission electron microscope sample support net and the magnetic powder particles, and at the same time, the magnetic powder particles can be embedded in the pores of the transmission electron microscope sample support net, and the existing air is exhausted as much as possible to make it as thin as possible, thereby reducing the subsequent mechanical thinning process time. Avoid introducing excess stress and impurities due to the mechanical thinning process. Place it in a heating furnace for heating and heat preservation, so that the special resin for ion thinning is completely cured. The magnetic powder particles can be further fixed by curing the special resin for ion thinning, ensuring that they will not fall off and move during subsequent processing and transmission electron microscope observation. Select a suitable area for ion thinning for transmission electron microscope observation. The invention can enable transmission electron microscope microstructure observation of magnetic powder particles, ensuring that the magnetic powder particles can be stable and motionless under high-intensity magnetic field conditions. Transmission electron microscope observation of the microstructure of magnetic powder particles becomes possible.

[0030] The above is only a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered as the protection scope of the present invention.

Claims

1. A method for preparing a transmission electron microscope sample of magnetic powder particles, characterized in that: The method comprises the following steps: embedding magnetic powder particles in a transmission electron microscope sample support net, further fixing them with a special resin for ion thinning, respectively arranging thin film materials on the upper and lower layers, applying pressure with a clamp to evenly distribute the special resin for ion thinning, completely wrapping the transmission electron microscope sample support net and the magnetic powder particles, exhausting the existing air, heating and heat preservation and then cooling, taking out the support net, preparing a thin area, and obtaining a transmission electron microscope sample of magnetic powder particles; the thin film is a metal thin film, specifically aluminum foil; The specific steps are as follows: (1) Place a metal block with a smooth surface on the bottom layer; (2) Lay a layer of aluminum foil on the metal block, and place several transmission electron microscope sample holders on the aluminum foil; (3) Evenly lay a layer of magnetic powder particles on the transmission electron microscope sample holder, and then drip a special resin for ion thinning of transmission electron microscope samples; (4) Cover the upper layer of the resin with aluminum foil to make a thin sheet with aluminum foil wrapped on both the top and the bottom; (5) Place a metal block with a smooth surface on the upper layer of the aluminum foil, with an aluminum foil sheet between the two metal blocks, and with the transmission electron microscope sample holder, magnetic powder particles, and transmission electron microscope sample holder in the middle of the aluminum foil sheet. (6) Use a clamp to clamp the two metal blocks containing the aluminum foil, and evenly apply force to the metal blocks so that the magnetic powder particles are embedded in the holes of the transmission electron microscope sample holder; (7) Put the clamp with the aluminum foil into a heating furnace to heat and keep it warm; (8) After cooling, take out the aluminum foil and use a carving knife to take out the transmission electron microscope sample holder according to the contour of the transmission electron microscope sample holder; (9) Use an ion thinning instrument to bombard the aluminum foil transmission electron microscope sample surface at a large angle to thin the magnetic powder particles and obtain a magnetic powder particle transmission electron microscope sample.

2. The method for preparing a magnetic powder particle transmission electron microscope sample according to claim 1, characterized in that: The clamp comprises an upper fixing plate (1), a lower fixing plate (2), a bolt (3) and a pressure block (4); four bolt holes are equidistantly provided at corresponding positions of the upper fixing plate (1) and the lower fixing plate (2); bolts (3) are provided in the bolt holes; the upper fixing plate (1) and the lower fixing plate (2) are adjusted by the bolts (3); and the pressure block (4) is placed between the upper fixing plate (1) and the lower fixing plate (2).

Images