Method for obtaining single crystal iron atomic-scale clean surface

Abstract

The invention discloses a method for obtaining a single crystal iron atomic-scale clean surface, and belongs to the technical field of material science and surface engineering.The method comprises the following steps that under the room temperature and ultrahigh vacuum, electron beams are adopted for conducting surface treatment on a single crystal iron sample, and the single crystal iron atomic-scale clean surface is obtained; wherein the surface treatment process comprises electron beam cutting and electron beam irradiation. According to the method, the electron beam is used for accurately treating the surface oxide layer under the high-vacuum condition, the atomic-scale clean single crystal iron surface can be effectively obtained, and the problem that the oxide layer on the iron surface is difficult to completely remove through existing (electro) chemical cleaning and mechanical polishing is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of material science and surface engineering, and in particular relates to a method for obtaining a clean surface at the atomic level of single crystal iron. Background Art

[0002] The atomically clean surface of single-crystal iron is of great significance to the fields of surface science, catalysis, and thin film growth. Existing surface treatment methods include electrochemical cleaning and mechanical polishing. Among them, electrochemical cleaning removes the surface oxide layer and pollutants by applying an electric current in the electrolyte to cause anodic dissolution or cathodic reduction reaction on the surface of single-crystal iron. However, after electrochemical cleaning, ions in the electrolyte may remain on the surface, requiring further cleaning. In addition, new impurities may be introduced or the chemical composition of the surface may be changed during the cleaning process. Mechanical polishing is a common surface treatment method that is widely used to remove oxide layers, scratches, and other defects on metal surfaces. However, this method may introduce problems such as surface damage, impurity contamination, and incomplete removal of the oxide layer. In addition, the above two methods have obvious disadvantages in treating the surface oxide layer of single-crystal iron, especially in applications with high requirements for surface quality and microstructure, and cannot obtain an atomically clean surface.

[0003] Therefore, there is an urgent need to provide a new atomic-level surface treatment method to obtain single-crystalline iron. Summary of the invention

[0004] In view of the above technical problems, the present invention proposes a method for obtaining a clean surface of single crystal iron at the atomic level.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for obtaining an atomically clean surface of single-crystalline iron comprises the following steps:

[0007] At room temperature and ultra-high vacuum conditions, the single crystal iron sample was surface treated with an electron beam to obtain an atomic-level clean surface of the single crystal iron.

[0008] Optionally, the ultra-high vacuum condition is: the vacuum degree is 4.0×10 -9 mbar-3.2×10 -7 mbar.

[0009] Optionally, the preparation process of the single crystal iron sample is:

[0010] The iron oxide is reduced at high temperature under closed conditions using hydrogen to obtain the single crystal iron sample.

[0011] Further, the pressure of the hydrogen is 1 bar; and / or

[0012] The iron oxide is ferric oxide and / or ferroferric oxide powder.

[0013] Further, the high temperature reduction process is specifically as follows:

[0014] The temperature was raised to 400-800°C at a heating rate of 20-30°C / min, and then kept at this temperature for 1-5h.

[0015] Optionally, the method for obtaining an atomically clean surface of single-crystalline iron comprises the following steps:

[0016] (1) Under room temperature, the single crystal iron sample was quickly transferred to the electron microscope sample holder for transmission electron microscopy observation;

[0017] (2) The electron microscope in step (1) is converted into a vacuum mode, and the electron beam roller of the electron microscope is used to move the electron beam to perform surface treatment on the oxide layer on the surface of the single crystal iron, thereby obtaining an atomic-level clean surface of the single crystal iron.

[0018] Furthermore, the surface treatment in step (2) includes electron beam cutting and electron beam irradiation.

[0019] Furthermore, when the surface treatment is electron beam cutting, the electron beam is converged to a point, wherein the energy of the electron beam is 300 KV and the dose rate of the electron beam is The cutting time is 1-10s.

[0020] Beneficial effects: The present invention utilizes electron beam to cut the surface oxide layer of a single crystal sample, which has the following advantages:

[0021] Electron beam cutting uses a highly focused high-energy electron beam, concentrated on a very small area, which can quickly remove the surface oxide layer and achieve atomic-level surface treatment.

[0022] Furthermore, when the surface treatment is electron beam irradiation, the energy of the electron beam is 300KV and the dose rate of the electron beam is The irradiation time is 200s-300s.

[0023] Beneficial effects: The present invention utilizes electron beam irradiation to remove the oxide layer on the surface of a single crystal sample, which has the following advantages:

[0024] 1. The electron beam has extremely high spatial resolution, which can precisely control the irradiation area at the nanoscale to avoid affecting non-target areas, which is especially important for samples with complex shapes or fine structures;

[0025] 2. There is no mechanical contact between the electron beam and the surface, avoiding scratches or surface damage that may be introduced by traditional mechanical polishing;

[0026] 3. Compared with traditional chemical cleaning or thermal annealing methods, electron beam irradiation can remove the oxide layer in a short time, which is particularly suitable for batch processing;

[0027] 4. Electron beam irradiation does not use any chemical reagents and will not introduce new impurities on the surface of the iron crystal.

[0028] Compared with the prior art, the present invention has the following advantages and technical effects:

[0029] 1. The present invention provides an efficient and reliable method for preparing an atomically clean surface of single-crystalline iron. By using an electron beam to precisely cut the surface oxide layer and contaminants or irradiate the surface oxide layer and contaminants under ultra-high vacuum conditions, an atomically clean single-crystalline iron surface can be effectively obtained.

[0030] 2. The method of the present invention is accurate and efficient, suitable for surface science research and high-precision material preparation, and can significantly improve the surface cleanliness of material samples, which is of great significance to the field of materials science. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0032] Figure 1 This is a TEM image before electron beam cutting in step S3 of Example 1 of the present invention;

[0033] Figure 2 This is a high-resolution transmission electron microscope image of the oxide layer after electron beam cutting in step S4 of Example 1 of the present invention;

[0034] Figure 3 TEM image (left) before electron beam irradiation in step S3 of Example 2 of the present invention and a high-resolution transmission electron microscope image after electron beam irradiation of the oxide layer in step S4. DETAILED DESCRIPTION

[0035] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0036] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0037] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0038] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0039] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0040] The embodiment of the present invention discloses a method for obtaining a clean surface of single crystal iron at the atomic level, comprising the following steps:

[0041] S1: Powdered iron oxide is loaded in a heating container;

[0042] S2: At room temperature, pure gas is added to the heating container for gas replacement, and high-temperature reduction is performed in a closed environment. After gas replacement, high-temperature reduction is performed in a closed environment to obtain single crystal iron. The pure gas is 1 bar, and the temperature is raised to 400-800°C, and then kept warm for 1-5 hours;

[0043] S3: The powder sample after high-temperature reduction in S2 is naturally cooled to room temperature, and then the powder sample is quickly transferred to the electron microscope sample rod for transmission electron microscopy observation;

[0044] S4: The electron microscope in S3 is converted into a vacuum mode. The single crystal iron with an oxide layer in S3 is placed at room temperature. The electron beam roller of the electron microscope is used to move the electron beam to process the oxide layer on the surface of the single crystal iron to obtain an atomically clean surface of the single crystal iron.

[0045] In some optional embodiments, the iron oxide powder in S1 is single crystal ferric oxide or ferrous oxide nanosheets.

[0046] In some optional embodiments, the heating rate in S2 is 20-30° C. / min.

[0047] In some optional embodiments, the pure gas in the S2 heating container is H2, and the gas replacement purge time is 20 minutes.

[0048] In some optional embodiments, the electron beam treatment in S4 is to obtain a clean surface of single crystal iron at atomic level by electron beam cutting or irradiation.

[0049] The "room temperature" in the present invention refers to 20-30°C unless otherwise specified.

[0050] The raw materials used in the present invention are all purchased from the market.

[0051] The technical solution of the present invention is further described below by way of examples. In the following example 1, electron beam cutting refers to: using a transmission electron microscope to focus an electron beam into a point, and then using a trackball device to move the electron beam to achieve the purpose of cutting the oxide layer on the surface of the single crystal iron.

[0052] Example 1

[0053] A method for obtaining an atomically clean surface of single-crystalline iron comprises the following steps:

[0054] S1: Select single crystal ferric oxide powder as raw material and load it in a heating container;

[0055] S2: Put the ferric oxide powder in S1 into a quartz tube, introduce 1 bar of hydrogen, seal the quartz tube, introduce H2 for high-temperature reduction, and heat up at a rate of 20°C / min. After heating to 800°C, keep warm for 5 hours. Before high-temperature reduction, first purge hydrogen in the quartz tube for 20 minutes at room temperature. After high-temperature reduction, a single crystal iron sample will be obtained in a hydrogen environment;

[0056] S3: The heating chip after high-temperature reduction in S2 is naturally cooled to room temperature, and the powder sample in the quartz tube is taken out from the glove box. The powder sample is transferred to the electron microscope sample rod and inserted into the electron microscope, and then the transmission electron microscope is observed. Before the electron microscope sample rod is inserted into the electron microscope, the single crystal iron is in contact with the air to form an oxide layer. The electron microscope image of the single crystal iron and the oxide is as follows: Figure 1 As shown;

[0057] S4: Convert the electron microscope in S3 to ultra-high vacuum mode with a vacuum degree of 3.2×10 -7mbar, a single crystal iron with an oxide layer in S3 is placed at room temperature, and an electron beam is focused into a point (the energy of the electron beam is 300KV, and the dose rate of the electron beam is The cutting time is 10s), and the electron beam roller of the electron microscope is used to move the electron beam to cut the oxide layer on the surface of the single crystal iron to obtain a clean surface at the atomic level of the single crystal iron, such as Figure 2 shown.

[0058] The above results show that electron beam cutting can obtain an atomically clean iron surface under high vacuum environment.

[0059] Example 2

[0060] A method for obtaining an atomically clean surface of single-crystalline iron comprises the following steps:

[0061] S1: Select single crystal ferric oxide powder as raw material and load it in a heating container;

[0062] S2: Put the ferric oxide powder in S1 into a quartz tube, introduce 1 bar of hydrogen, seal the quartz tube, introduce H2 for high-temperature reduction, and heat up at a rate of 20°C / min. After heating to 800°C, keep warm for 5 hours. Before high-temperature reduction, first purge hydrogen in the quartz tube for 20 minutes at room temperature. After high-temperature reduction, a single crystal iron sample will be obtained in a hydrogen environment;

[0063] S3: The heating chip after high-temperature reduction in S2 is naturally cooled to room temperature, and the powder sample in the quartz tube is taken out from the glove box. The powder sample is transferred to the electron microscope sample rod and inserted into the electron microscope, and then the transmission electron microscope is observed. Before the electron microscope sample rod is inserted into the electron microscope, the single crystal iron is in contact with the air to form an oxide layer. The electron microscope image of the single crystal iron and the oxide is as follows: Figure 3 As shown;

[0064] S4: Convert the electron microscope in S3 to ultra-high vacuum mode with a vacuum degree of 3.2×10 -7 mbar, the single crystal iron with oxide layer in S3 was irradiated by moving electron beam on the iron single crystal using electron beam roller of electron microscope at room temperature (energy of electron beam was 300KV, and dose rate of electron beam was The irradiation time is 219s) to obtain a clean surface of single crystal iron at atomic level, such as Figure 3 shown.

[0065] The above results show that electron beam irradiation can obtain an atomically clean iron surface under high vacuum environment.

[0066] The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for obtaining an atomically clean surface of single-crystalline iron, characterized in that: The following steps are involved: At room temperature and ultra-high vacuum conditions, the single crystal iron sample was surface treated with an electron beam to obtain an atomic-level clean surface of the single crystal iron.

2. A method for obtaining an atomically clean surface of single-crystalline iron according to claim 1, characterized in that: The vacuum degree of the ultra-high vacuum is 4.0×10 -9 mbar-3.2×10 -7 mbar.

3. A method for obtaining an atomically clean surface of single-crystalline iron according to claim 1, characterized in that: The preparation process of the single crystal iron sample is as follows: The iron oxide is reduced at high temperature under closed conditions using hydrogen to obtain the single crystal iron sample.

4. A method for obtaining an atomically clean surface of single-crystalline iron according to claim 3, characterized in that: The pressure of the hydrogen is 1 bar; and / or The iron oxide is ferric oxide and / or ferroferric oxide powder.

5. The method for obtaining an atomically clean surface of single-crystalline iron according to claim 3, characterized in that: The high temperature reduction process is specifically as follows: The temperature was raised to 400-800°C at a heating rate of 20-30°C / min, and then kept at this temperature for 1-5h.

6. The method for obtaining an atomically clean surface of single-crystalline iron according to claim 1, characterized in that: The method for obtaining a clean surface of single-crystal iron at the atomic level specifically comprises the following steps: (1) Under room temperature, the single crystal iron sample was quickly transferred to the electron microscope sample holder for transmission electron microscopy observation; (2) The electron microscope in step (1) is converted into a vacuum mode, and the electron beam roller of the electron microscope is used to move the electron beam to perform surface treatment on the oxide layer on the surface of the single crystal iron, thereby obtaining an atomic-level clean surface of the single crystal iron.

7. A method for obtaining an atomically clean surface of single-crystalline iron according to claim 6, characterized in that: The surface treatment in step (2) includes electron beam cutting and electron beam irradiation.

8. The method for obtaining an atomically clean surface of single-crystalline iron according to claim 7, characterized in that: When the surface treatment is electron beam cutting, the electron beam is focused to a point, wherein the energy of the electron beam is 300KV and the dose rate of the electron beam is The cutting time is 1s-10s.

9. The method for obtaining an atomically clean surface of single-crystalline iron according to claim 7, characterized in that: When the surface treatment is electron beam irradiation, the energy of the electron beam is 300KV, and the dose rate of the electron beam is The irradiation time is 200s-300s.

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