Sample particle observation method, and manufacturing method of sample for transmission electron microscope

Abstract

To provide a technique for observing sample particles using a transmission electron microscope, while restricting contamination due to scattering of the sample particles.SOLUTION: A sample particle observation method using a transmission electron microscope includes: a sample particle adhesion step for making sample particles adhere to a metal mesh with supporting film; a sample particle catching step for sandwiching sample particles by using two metal meshes with supporting film; and an observation step for observing the sample particles caught by the two metal meshes with supporting film, by using a transmission electron microscope.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for observing a sample particle and a method for preparing a sample for a transmission electron microscope. [Background technology]

[0002] In order to analyze microparticles (hereinafter referred to as sample particles) constituting a powder sample, the sample particles may be observed using a transmission electron microscope. For example, Patent Document 1 discloses a method for preparing a thin sample for observing a powder, which is characterized by comprising a mixing step of obtaining a mixture of the powder and a resin, and a pressurizing step of applying pressure to the mixture to form a thin sample. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2003-294594 A Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a technique for observing sample particles using a transmission electron microscope while suppressing contamination due to scattering of sample particles. [Means for solving the problem]

[0005] The first aspect of the present invention is A method for observing a sample particle using a transmission electron microscope, comprising the steps of: a sample particle attachment step of attaching the sample particles to a metal mesh with a support film; a sample particle clamping step of clamping the sample particle between two of the metal meshes with support films; and observing the sample particle sandwiched between the two metal meshes with support film by the transmission electron microscope.

[0006] A second aspect of the present invention is In the sample particle attachment step, the sample particle is transferred onto the support film, which is the sample particle observation method according to the first aspect.

[0007] A third aspect of the present invention is In the sample particle sandwiching step, the sample particle is sandwiched between the support films, which is the sample particle observation method according to the first aspect.

[0008] A fourth aspect of the present invention is In the sample particle attachment step, the sample particle is transferred in a solid state onto the metal mesh with a support film without using a solvent, in the method for observing a sample particle according to the first aspect.

[0009] A fifth aspect of the present invention is The sample particle adhering step and the sample particle sandwiching step are carried out under an inert atmosphere; The method further includes a TEM holder storage step of storing the sample particle sandwiched between the two metal meshes with support films in a TEM holder for observation without exposure to air under an inert atmosphere; In the observation step, the TEM holder for non-exposure-to-air observation is introduced into the transmission electron microscope to observe the sample particle, which is the method for observing a sample particle according to the first aspect.

[0010] A sixth aspect of the present invention is a method for producing a composition comprising the steps of: In the method for observing a sample particle according to any one of the first to fifth aspects, the sample particle contains an alkali metal salt or an alkaline earth metal salt.

[0011] A seventh aspect of the present invention is A method for preparing a transmission electron microscope specimen including a sample particle, comprising the steps of: a sample particle attachment step of attaching the sample particles to a metal mesh with a support film; and a sample particle clamping step of clamping the sample particle between two of the metal meshes with supporting film. Effect of the Invention

[0012] According to the present invention, sample particles can be observed using a transmission electron microscope while suppressing contamination caused by scattering of the sample particles. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a flowchart showing an example of a method for observing a sample particle according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram illustrating the sample particle adhering step S101 and the sample particle sandwiching step S102 according to the first embodiment of the present invention. [Diagram 3] FIG. 3 is a schematic cross-sectional view of a metal mesh 20 with a support film according to the first embodiment of the present invention. [Figure 4] FIG. 4 is a TEM observation image of a sample particle 10 according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] <Inventor's findings> First, the findings of the present inventors will be described.

[0015] When observing sample particles with a particle size of about 100 nm using a transmission electron microscope (hereinafter also referred to as TEM), thin section processing as described in Patent Document 1 is not necessary. For example, the sample particles can be fixed to a metal mesh with a supporting film and then directly observed.

[0016] However, if the sample particles are not fixed sufficiently, some of them may scatter in the TEM sample chamber and adhere to the CCD camera, etc., resulting in contamination. In particular, when the sample particles are fixed to the metal mesh with a supporting film by transferring and fixing the solid sample particles to the metal mesh with a supporting film without using a solvent, the sample particles are fixed by static electricity, so that the sample particles are likely to scatter in the TEM sample chamber under high vacuum, easily causing contamination.

[0017] The present inventors have conducted extensive research into the above-mentioned problems, and have found that by adhering a sample particle to a metal mesh with a supporting film and then sandwiching the sample particle between two metal meshes with supporting films, it is possible to perform TEM observation while suppressing the scattering of the sample particle in the TEM sample chamber.

[0018] First embodiment of the present invention (1) Observation method of sample particles A method for observing a sample particle according to this embodiment will be described.

[0019] Fig. 1 is a flow chart showing an example of a sample particle observation method of this embodiment. As shown in Fig. 1, the sample particle observation method of this embodiment includes, for example, a sample particle attachment step S101, a sample particle clamping step S102, and an observation step S103. In addition, a TEM holder storage step S104 may be performed between the sample particle clamping step S102 and the observation step S103.

[0020] (Sample particle attachment step S101) 2 is a schematic diagram illustrating a sample particle adhering step S101 and a sample particle sandwiching step S102 of this embodiment. As shown in FIG. 2, the sample particle adhering step S101 is, for example, a step of adhering a sample particle 10 to a metal mesh 20 with a support film.

[0021] The sample particle 10 used in this embodiment is, for example, a powder containing an alkali metal salt or an alkaline earth metal salt. In this case, when the sample particle 10 is fixed to the metal mesh 20 with a supporting film, if the sample particle 10 is dispersed in a solvent, the alkali metal salt or the alkaline earth metal salt reacts with the solvent, and the shape and the like of the particle cannot be observed accurately. Therefore, in the sample particle attachment step S101, it is preferable to transfer the sample particle 10 in a solid state onto the metal mesh 20 with a supporting film without using a solvent. This allows the shape, particle size, and the like of the sample particle 10 to be observed accurately. The particle size of the sample particle 10 is not particularly limited, but is, for example, 10 to 1000 nm.

[0022] Fig. 3 is a schematic cross-sectional view of a metal mesh 20 with a support film used in this embodiment. As shown in Fig. 3, the metal mesh 20 with a support film is configured by forming a support film portion 22 on a metal mesh portion 21. The metal mesh portion 21 is made of copper, for example, with a diameter of 1 to 3 mm and a thickness of 10 to 30 µm, and has a large number of through holes formed at a pitch of 50 to 300 µm. The support film portion 22 is, for example, configured by laminating a polymer film and a carbon film, and has a film thickness of about 20 nm.

[0023] In the sample particle attachment step S101, for example, it is preferable to transfer the sample particle 10 onto the support film part 22. To transfer the sample particle 10 onto the support film part 22, for example, the metal mesh 20 with the support film may be held using tweezers or the like, the surface on the support film part 22 side may be brought close to the sample particle 10, and the sample particle 10 may be attached to the support film part 22 by static electricity.

[0024] Although the amount of sample particles 10 attached to the metal mesh 20 with a support film is not particularly limited, if an excessive amount of sample particles 10 is attached, it may be difficult to observe the sample particles 10 by TEM in the observation step S103. Therefore, after the sample particles 10 are attached to the metal mesh 20 with a support film, the metal mesh 20 with a support film may be vibrated to shake off some of the attached sample particles 10.

[0025] (Sample particle clamping step S102) The sample particle sandwiching step S102 is, for example, a step of sandwiching the sample particle 10 between two metal meshes 20 with a support film. Specifically, as shown in FIG. 2, the metal mesh 20 with a support film to which the sample particle 10 is attached in the sample particle attachment step S101 is placed with the side to which the sample particle 10 is attached facing up, and another metal mesh 20 with a support film is placed on top of it. The sample particle sandwiching step S102 completes a TEM sample. In the TEM sample completed in a series of steps, scattering of the sample particle 10 in the TEM sample chamber can be suppressed in the observation step S103. In addition, since a large number of through holes are formed in the two metal meshes 20 with a support film, an electron beam can pass through the overlapping portion of the through holes of the two metal meshes 20 with a support film, and TEM observation can be performed.

[0026] In the sample particle sandwiching step S102, for example, it is preferable to sandwich the sample particle 10 between the support film part 22. That is, it is preferable to transfer the sample particle 10 onto the support film part 22 in the sample particle attachment step S101, and to place another metal mesh 20 with a support film on the metal mesh 20 with the support film to which the sample particle 10 has been attached, so that the sample particle 10 is sandwiched between the support film part 22 in the sample particle sandwiching step S102. This makes it possible to suppress scattering of the sample particle 10 within the TEM sample chamber in the observation step S103.

[0027] (Observation step S103) The observation step S103 is, for example, a step of observing a sample particle 10 sandwiched between two metal meshes 20 with support films, which are samples for TEM, with a transmission electron microscope. Since the sample particle 10 is sandwiched between the two metal meshes 20 with support films, it is difficult for the particle to scatter even in a TEM sample chamber in a high vacuum state, and contamination of the device can be suppressed. In addition, since an electron beam passes through the overlapping portion of the through holes of the two metal meshes 20 with support films, the sample particle 10 can be observed with a TEM even when sandwiched between the two metal meshes 20 with support films. Furthermore, if the element is other than the constituent elements of the mesh, a TEM equipped with an energy dispersive X-ray spectroscopy device (EDS) can be used to perform composition analysis in the sample. The specifications of the transmission electron microscope and the observation method are not particularly limited, and known methods can be used.

[0028] (TEM holder storage process S104) Alternatively, the sample particle attachment step S101 and the sample particle sandwiching step S102 may be performed in a glove box under an inert atmosphere, and then a TEM holder storage step S104 may be performed in which the sample particle 10 sandwiched between two metal meshes 20 with support films is stored in a known TEM holder for observation without exposure to the atmosphere in the glove box under an inert atmosphere. Then, in the observation step S103, the TEM holder for observation without exposure to the atmosphere may be introduced into a transmission electron microscope to observe the sample particle 10. This makes it possible to observe powders that easily react with components in the atmosphere.

[0029] When the TEM holder storing step S104 is performed, the sample particle attaching step S101 and the sample particle sandwiching step S102 are performed in an inert atmosphere, and the sample particle is thus the same as the above-mentioned sample particle attaching step S101 and sample particle sandwiching step S102, so that the obtained TEM sample can suppress scattering of the sample particles 10 in the TEM sample chamber in the observation step S103. In addition, since a large number of through-holes are formed in the two metal meshes 20 with support films, an electron beam can pass through the overlapping portions of the through-holes of the two metal meshes 20 with support films, and TEM observation can be performed.

[0030] Depending on the type of sample particle 10, the surface of the sample particle 10 may be altered or a precipitate may be generated due to exposure to the atmosphere. In particular, when the sample particle 10 is a particle containing an alkali metal salt, an alkaline earth metal salt, or a phosphate compound, the particle may be altered and a precipitate may be generated due to exposure to the atmosphere. As a result, the intended observation may not be possible due to exposure to the atmosphere. When the sample particle 10 is altered and a precipitate is generated due to exposure to the atmosphere, it is desirable that the powder sample to be the sample particle 10 is placed in a sealed container filled with the same atmosphere as the glove box to be used after sampling and then carried into the glove box. Then, the sealed container is opened in the glove box, the sample particle 10 is separated from the powder sample, and the sample particle attachment step S101 may be performed. Here, the inert atmosphere is an atmosphere of an inert gas such as nitrogen gas or argon gas. The inside of the TEM holder for non-exposure to the atmosphere observation is the same inert atmosphere as the glove box.

[0031] Through the above steps, the sample particles 10 can be observed under a transmission electron microscope while preventing contamination due to scattering of the sample particles 10.

[0032] The present invention can also be applied to a method for preparing a specimen for a transmission electron microscope. In that case, only the specimen particle attachment step S101 and the specimen particle clamping step S102 may be performed, and the observation step S103 may be omitted.

[0033] (2) Effects of this embodiment According to this embodiment, one or more of the following advantages are achieved.

[0034] (a) In the method for observing a sample particle of this embodiment, TEM observation is performed in a state where the TEM sample has the sample particle 10 sandwiched between two metal meshes 20 with supporting films. This makes it possible to perform TEM observation while suppressing contamination due to scattering of the sample particle 10.

[0035] (b) In the sample particle clamping step S102 of the present embodiment, it is preferable to clamp the sample particle 10 with the support film portion 22. Thereby, when observing the sample particle 10 with a TEM in the observation step S103, the metal mesh portion 21 is unlikely to come into the field of view, so that TEM observation can be performed while suppressing contamination due to scattering of the sample particle 10.

[0036] (c) In the sample particle attachment step S101 of the present embodiment, it is preferable to transfer the sample particle 10 in a solid state onto the metal mesh 20 with the support film without using a solvent. This allows the particle shape, particle size, etc. of the sample particle 10 to be accurately observed.

[0037] (d) The method for observing sample particles of this embodiment is particularly suitable because it allows accurate observation of the particle shape, particle size, etc., even when the sample particle 10 is a powder containing an alkali metal salt or an alkaline earth metal salt.

[0038] <Other embodiments of the present invention> Although the embodiment of the present invention has been specifically described above, the present invention is not limited to the above-mentioned embodiment, and various modifications can be made without departing from the gist of the present invention.

[0039] For example, in the above embodiment, the sample particle 10 is a powder containing an alkali metal salt or an alkaline earth metal salt, but the present invention can also be applied to a case where the sample particle 10 is a powder not containing an alkali metal salt or an alkaline earth metal salt. In this case as well, TEM observation can be performed while suppressing contamination due to scattering of the sample particle 10.

[0040] Furthermore, for example, in the above embodiment, the case where the sample particle 10 is transferred as a solid onto the metal mesh 20 with a support film without using a solvent has been described, but if the sample particle 10 does not react easily with a solvent, the sample particle 10 may be dispersed in a solvent, an appropriate amount of the solvent in which the sample particle 10 is dispersed may be dropped onto the metal mesh 20 with a support film, and then the sample particle 10 may be fixed to the metal mesh 20 with a support film by drying. In this case as well, by performing TEM observation while sandwiching the sample particle 10 between two metal meshes 20 with support films, it is possible to perform TEM observation while suppressing contamination due to scattering of the sample particle 10. EXAMPLES

[0041] Next, examples of the present invention will be described. These examples are merely examples of the present invention, and the present invention is not limited to these examples.

[0042] Example 1 A sample particle 10 (average particle size: about 500 nm) containing an alkali metal salt was prepared. Elastic carbon, ELS-C10, and Cu100P grids (manufactured by Oken Shoji Co., Ltd.) were used as the metal mesh 20 with a support film, and the sample particle 10 was transferred onto the support film portion 22.

[0043] Thereafter, a metal mesh 20 with a support film of the same specifications was placed on the metal mesh 20 with the support film to which the sample particle 10 had been transferred, so that the sample particle 10 was sandwiched between the support film portions 22, thereby obtaining a TEM sample for Example 1.

[0044] The obtained TEM sample according to Example 1 was introduced into a transmission electron microscope (JEM-ARM200F, manufactured by JEOL Ltd.), and the sample particle 10 was observed under the condition of an acceleration voltage of 200 kV. The obtained observation image is shown in FIG.

[0045] As shown in Fig. 4, it was confirmed that the shape and particle size of the sample particle 10 can be observed by TEM even when the sample particle 10 is sandwiched between two metal meshes 20 with supporting films. In addition, when the inside of the sample chamber was checked after the TEM observation, it was confirmed that the sample particle 10 had not scattered and the apparatus was not contaminated.

[0046] Example 2 A sealed container containing a powder sample of the same sample particle 10 as in Example 1 was prepared and placed in a glove box. The atmosphere in the glove box was replaced with Ar gas. In addition, a metal mesh 20 with a support film was placed in the glove box as in Example 1.

[0047] The sealed container was opened, and the sample particles 10 were taken from the powder sample, and the sample particles 10 were transferred onto the support film part 22. Then, in the glove box, a metal mesh 20 with a support film of the same specifications was placed on the metal mesh 20 with the support film to which the sample particles 10 were transferred, so that the sample particles 10 were sandwiched by the support film part 22, to obtain a TEM sample according to Example 2. The TEM sample according to Example 2 was stored in a TEM holder for non-exposure to air observation. The TEM holder for non-exposure to air observation was sealed and removed from the glove box. The TEM holder for non-exposure to air observation was introduced into the TEM, and the TEM sample according to Example 2 was observed in the same manner as in Example 1. It was confirmed that observation could be performed in Example 2, the sample particles 10 according to Example 2 did not scatter, and the device was not contaminated. [Explanation of symbols]

[0048] 10 Sample particles 20 Metal mesh with supporting membrane 21 Metal mesh section 22 Support membrane part S101 Sample particle attachment process S102 Sample particle clamping process S103 Observation process S104 TEM holder storage process

Claims

1. A method for observing a sample particle using a transmission electron microscope, comprising the steps of: a sample particle attachment step of attaching the sample particles to a metal mesh with a support film; a sample particle sandwiching step of sandwiching the sample particle between two of the metal meshes with support films; and observing the sample particle sandwiched between the two metal meshes with support films using the transmission electron microscope.

2. 2. The method for observing a sample particle according to claim 1, wherein in the sample particle adhering step, the sample particle is transferred onto the support film.

3. 2. The method for observing a sample particle according to claim 1, wherein in the sample particle sandwiching step, the sample particle is sandwiched between the support films.

4. 2. The method for observing a sample particle according to claim 1, wherein in the sample particle attachment step, the sample particle is transferred in a solid state onto the metal mesh with a supporting film without using a solvent.

5. The sample particle adhering step and the sample particle sandwiching step are carried out under an inert atmosphere; The method further includes a TEM holder storing step of storing the sample particle sandwiched between the two metal meshes with support films in a TEM holder for observation without exposure to air under an inert atmosphere, 2. The method for observing a sample particle according to claim 1, wherein in the observation step, the TEM holder for non-exposure to air observation is introduced into the transmission electron microscope to observe the sample particle.

6. 6. The method for observing a sample particle according to claim 1, wherein the sample particle contains an alkali metal salt or an alkaline earth metal salt.

7. A method for preparing a transmission electron microscope specimen including a sample particle, comprising the steps of: a sample particle attachment step of attaching the sample particles to a metal mesh with a support film; a sample particle sandwiching step of sandwiching the sample particle between two of the metal meshes with supporting film.

Images