Method for removing carbon from to-be-detected sample of in-situ transmission electron microscope and application
By removing deep adsorption of hydrocarbons in nanocarbide samples under vacuum conditions and high-temperature insulation steps, the problem of carbon deposit in in-situ transmission electron microscopy affects imaging and observation, and an efficient carbon removal effect is achieved.
Patent Information
- Application Number
- CN202510349058.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-24
- Publication Date
- 2025-06-20
AI Technical Summary
In in situ transmission electron microscopy, deeply adsorbed hydrocarbon carbon deposits in nanocarbide samples affect real-time observation of imaging effects and real reactions.
Under vacuum conditions, the organic matter in the sample to be tested is volatile by heating step, and the volatile organic matter is extracted by vacuum, the high-temperature insulation step makes the unvolatile organic matter carbonized, and finally the inert gas is purged and the residual organic matter and impurities are removed.
Effectively remove deep carbon deposits in the sample to be tested, improve real-time observation effect and imaging quality in in-situ transmission electron microscopy, with simple steps and low cost.
Smart Images
Figure CN120177173A_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the technical field of transmission electron microscope sample preparation, and specifically relates to a method for removing carbon from a sample to be measured in an in-situ transmission electron microscope and its application. Background Art
[0002] In recent years, the in-situ transmission electron microscope technology has developed rapidly. Currently, in-situ heating and in-situ gas-phase transmission electron microscopes usually use an in-situ reaction chamber system, which generally consists of an upper chip + a lower chip, and there is a small window between the two chips serving as a micro-reaction chamber. This system can ensure that the sample to be observed is heated and undergoes gas-phase reactions under the conditions of high vacuum and high cleanliness in the transmission electron microscope chamber. Therefore, the in-situ reaction chamber system can obtain the microscopic structural changes on the surface of nanomaterials during heating and gas-phase reactions under real reaction conditions, which helps to study the reactions occurring in nanomaterials in real time and in depth.
[0003] Currently, there are mainly two sources of carbon deposition in the samples to be measured in the in-situ transmission electron microscope of nanocarbides: one source is the carbon deposition caused by solvents, adhesives, etc. during the in-situ transmission electron microscope sample preparation process; the second is the carbon deposition generated during the preparation of nanocarbides. For the first source of carbon deposition, the plasma cleaning technology can be used to remove it.
[0004] For the second source of carbon deposition, the methods for preparing nanocarbides are mainly chemical vapor deposition, precursor pyrolysis, carbothermal reduction reaction, etc. However, the reaction raw materials such as excessive carbon source gases and organic solvents used in these methods are likely to cause deep hydrocarbon adsorption on the nanocarbide samples, and these deeply adsorbed hydrocarbons are the second source of carbon deposition in nanocarbides. And these deeply adsorbed hydrocarbons (the second source of carbon deposition) have a great impact on the imaging effect of the sample to be measured under the in-situ transmission electron microscope, and also hinder the contact between nanocarbides and gas molecules under the in-situ transmission electron microscope, thereby affecting the real-time observation effect of the real reaction of nanocarbides under the in-situ transmission electron microscope. Summary of the Invention
[0005] To solve the above problems, this application proposes a method for removing carbon from a sample to be measured in an in-situ transmission electron microscope and its application. The carbon removal method can remove the deeply adsorbed hydrocarbons in the sample to be measured, and improve the real-time observation effect and imaging effect of the sample to be measured in the in-situ transmission electron microscope.
[0006] This application is achieved through the following technical solutions:
[0007] One of the purposes of this application is to provide a method for removing carbon from a sample to be measured in an in-situ transmission electron microscope, including the following steps:
[0008] Under vacuum conditions, perform carbon removal treatment on the sample to be measured to obtain the sample to be measured after carbon removal;
[0009] The decarbonization treatment includes a heating step, a heat preservation step, and a cooling step;
[0010] The temperature of the heat preservation step is 800°C to 1200°C.
[0011] The decarbonization method for the in-situ transmission electron microscopy sample to be measured provided by this application, under vacuum, the heating step volatilizes the organic matter in the sample to be measured, and uses vacuum (negative pressure) to extract the volatilized organic matter, and the high-temperature heat preservation step carbonizes the un-volatilized organic matter in the sample to be measured. The decarbonization method for the in-situ transmission electron microscopy sample to be measured provided by this application can effectively remove the deep carbon deposits (organic matter) remaining in the sample to be measured during the preparation process, with simple steps and low cost.
[0012] In some possible implementation manners, in the heating step, the heating rate is 20°C / min to 100°C / min.
[0013] In some possible implementation manners, in the heat preservation step, the heat preservation time is 30 min to 120 min.
[0014] In some possible implementation manners, the degree of vacuum of the vacuum condition is 10 -3 Pa to 10 Pa.
[0015] In some possible implementation manners, the degree of vacuum of the vacuum condition is 10 -3 Pa to 1 Pa.
[0016] In some possible implementation manners, background gas is continuously introduced and purged during the decarbonization treatment.
[0017] In some possible implementation manners, the flow rate of the background gas is 0.5 ml / min to 50 ml / min.
[0018] In some possible implementation manners, the background gas includes at least one of argon, nitrogen, helium, and neon.
[0019] In some possible implementation manners, the sample to be measured is a nanocarbonide, and the nanocarbonide includes at least one of SiC, ZrC, HfC, and TiC.
[0020] The second object of this application is to provide an application of the decarbonization method for the in-situ transmission electron microscopy sample to be measured provided by this application in the field of transmission electron microscopy sample preparation. Description of the Drawings
[0021] To more clearly illustrate the technical solutions in the embodiments of the present drawings or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present drawings. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.
[0022] Figure 1 It is a schematic flow chart of a method for removing carbon from a sample to be measured by an in-situ transmission electron microscope in an embodiment of the present invention.
[0023] Figure 2 It is an in-situ transmission electron microscope image of a sample to be measured prepared by a method for removing carbon from a sample to be measured by an in-situ transmission electron microscope in Embodiment 1 of the present application;
[0024] Figure 3 It is an in-situ transmission electron microscope image of a sample to be measured prepared by a method for removing carbon from a sample to be measured by an in-situ transmission electron microscope in Embodiment 2 of the present application;
[0025] Figure 4 It is an in-situ transmission electron microscope image of a sample to be measured prepared by a method for removing carbon from a sample to be measured by an in-situ transmission electron microscope in Embodiment 3 of the present application;
[0026] Figure 5 It is an in-situ transmission electron microscope image of a sample to be measured provided in Comparative Example 1 of the present application.
[0027] The realization of the purpose of the present drawings, functional features and advantages will be further described in conjunction with the embodiments with reference to the drawings. Detailed Embodiments
[0028] In order to make the purpose, technical solutions and advantages of the present application clearer, the following will describe and explain the present application in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application. Based on the embodiments provided by the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.
[0029] Obviously, the following description is only some examples or embodiments of the present application. For those of ordinary skill in the art, without creative efforts, the present application can also be applied to other similar scenarios. In addition, it can also be understood that although the efforts made in this development process may be complex and lengthy, for those of ordinary skill in the art related to the content disclosed in the present application, some design, manufacturing or production changes based on the technical content disclosed in the present application are only conventional technical means and should not be understood as the content disclosed in the present application being insufficient.
[0030] However, there are cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually identical structures are omitted. This is to avoid making the following descriptions unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the following descriptions are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter recited in the claims.
[0031] If there is no special description, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, and all technical features and optional technical features of the present application can be combined with each other to form new technical solutions.
[0032] An embodiment of the present application provides a method for removing carbon from a sample to be measured by in-situ transmission electron microscopy, as Figure 1 shown, including the following steps:
[0033] S1. Under vacuum conditions, perform carbon removal treatment on the sample to be measured to obtain the sample to be measured after carbon removal;
[0034] The carbon removal treatment includes a heating step, a heat preservation step, and a cooling step;
[0035] The temperature of the heat preservation step is 800 °C to 1200 °C.
[0036] The method for removing carbon from the sample to be measured by in-situ transmission electron microscopy provided by the embodiment of the present application, under vacuum, the heating step volatilizes the organic matter in the sample to be measured, and uses vacuum (negative pressure) to extract the volatilized organic matter, and the high-temperature heat preservation step carbonizes the organic matter that has not volatilized in the sample to be measured. The method for removing carbon from the sample to be measured by in-situ transmission electron microscopy provided by the embodiment of the present application can effectively remove the deep carbon deposition caused by the use of excessive organic solvents, methane, propylene, propane and other C 1-5 organic gases, excessive polycarbosilane and organic solvents, with simple steps and low cost.
[0037] In the embodiment, in the heat preservation step, the heat preservation temperature is 800 °C to 1200 °C, which can be typical but non-limiting temperatures such as 800 °C, 900 °C, 1200 °C or the range between any two temperatures. At this temperature, the organic matter that has not volatilized during the heating process can be fully carbonized to avoid affecting the imaging quality.
[0038] In some embodiments, in the above step S1, the vacuum degree of the vacuum condition is 10 -3 Pa to 10 Pa. In the exemplary example, it can be 10 -3Typical but non-limiting vacuum degrees such as 10-3 Pa, 1 Pa, 10 Pa, etc., or the range between any two vacuum degrees. In this case, a high vacuum degree is a low-pressure condition, which is beneficial for the organic matter in the sample to be measured to escape at a lower temperature during the heating step; moreover, the oxygen content in the high vacuum degree is low, and it is easy to carbonize and remove the organic matter in the sample to be measured during heat preservation.
[0039] In some specific embodiments, the vacuum degree of the vacuum condition is 10-3 -3 Pa to 1 Pa.
[0040] In some embodiments, in the above step S1, during the heating step, the heating rate is 20 °C / min to 100 °C / min, and it can be typical but non-limiting heating rates such as 20 °C / min, 50 °C / min, 100 °C / min, etc., or the range between any two heating rates. In this case, a higher heating rate combined with a low-pressure condition can quickly cause the organic matter molecules in the sample to be measured to escape, and then be removed by negative pressure.
[0041] In some embodiments, in the above step S1, during the heat preservation step, the heat preservation time is 30 min to 120 min, and it can be typical but non-limiting times such as 30 min, 60 min, 120 min, etc., or the range between any two times. Within this time range, the organic matter in the sample to be measured can be fully carbonized.
[0042] In some embodiments, in the above step S1, during the decarbonization treatment process, a background gas is continuously introduced for purging; the flow rate of the background gas is 0.5 ml / min to 50 ml / min. In exemplary embodiments, it can be typical but non-limiting flow rates such as 0.5 ml / min, 50 ml / min, etc., or the range between any two flow rates. In this case, the organic matter volatilized from the sample to be measured and the gas generated by the carbonization of the organic matter are removed synergistically by vacuum (negative pressure) and purging with a high-purity inert gas.
[0043] In some embodiments, the background gas includes at least one of argon, nitrogen, helium, and neon;
[0044] The purity of the background gas is above 99.999%. In this case, during the decarbonization treatment process, an inert gas such as high-purity argon or high-purity nitrogen with a purity of 99.999% is continuously introduced as the background gas for purging to remove the organic matter from the reaction system, and the organic matter volatilized from the sample to be measured and the gas generated by the carbonization of the organic matter can be removed more quickly.
[0045] In some embodiments, in the above step S1, the cooling step includes: cooling the sample to be measured to room temperature (20 °C to 25 °C). In this case, purging with an inert gas can remove the residual organic carbon on the surface of the sample to be measured, further reducing the residual carbon content of the sample to be measured.
[0046] In some embodiments, in the above step S1, the temperature of the sample to be tested is lowered by natural cooling.
[0047] In some embodiments, in the above step S1, the sample to be tested is a nanocarbide, and the nanocarbide includes at least one of SiC, ZrC, HfC, and TiC. In this case, the sample to be tested has good vacuum thermal stability and contains carbon elements, and no new impurities will be introduced during carbonization.
[0048] In some specific embodiments, a method for removing carbon from a sample to be tested in an in-situ transmission electron microscope is proposed, and the steps are as follows:
[0049] Step 1. After placing the sample to be tested in the sample preparation device, evacuate the air;
[0050] Among them, the evacuation step includes: evacuating the sample preparation device to reduce the pressure to a vacuum degree of 10 -3 Pa to 10 Pa, and then introducing an inert gas (such as high-purity argon, high-purity nitrogen, etc.) at a flow rate of 0.5 ml / min to 50 ml / min until the pressure of the sample preparation device is above 101 kPa; repeat the evacuation and inert gas introduction steps until the oxygen partial pressure in the vacuum system is 3×10 -4 Below, repeat 3 to 7 times.
[0051] Step 2. Carbon removal treatment: The following heating step, heat preservation step, and cooling step are carried out under the condition of continuously purging with a background gas with a flow rate of 0.5 ml / min to 50 ml / min:
[0052] Heating step, heat preservation step: Heat the sample to be tested to 800 °C to 1200 °C at a heating rate of 20 °C / min to 100 °C / min, and then keep it warm for 30 min to 120 min.
[0053] Cooling step: Cool the sample to be tested to room temperature (20 °C to 25 °C).
[0054] In some embodiments, in the above step 1, the sample preparation device includes an in-situ gas-thermal coupling sample rod or a high-vacuum muffle furnace.
[0055] The following further illustrates the method for removing carbon from a sample to be tested in an in-situ transmission electron microscope according to the embodiments of the present application with specific embodiments.
[0056] Example 1
[0057] Example 1 provides a method for removing carbon from a sample to be tested in an in-situ transmission electron microscope, and the steps are as follows:
[0058] ① Use SiC nanowires as the sample to be tested.
[0059] ② Place the SiC nanowires in the micro-reaction chamber of an in-situ gas-thermal coupling transmission electron microscope sample holder, and evacuate the vacuum in the micro-reaction chamber to 10 -3 Pa; then introduce high-purity argon (purity above 99.999%) at a flow rate of 0.5 ml / min to increase the pressure to 101 kPa; repeat the evacuation and argon introduction cycles 3 times to make the oxygen partial pressure in the system 3×10 -4 Pa.
[0060] ③ Under the condition of continuously purging with high-purity argon at a flow rate of 0.5 ml / min, heat the sample to be measured from room temperature (25°C) to 900°C at a heating rate of 50°C / min, hold for 60 min, and then cool to room temperature (25°C) to obtain carbon-free SiC nanowires.
[0061] Example 2
[0062] Example 2 provides a method for removing carbon from a sample to be measured by in-situ transmission electron microscopy. The steps are basically the same as those in Example 1, except that:
[0063] In step ③, the holding time is 30 min.
[0064] Example 3
[0065] Example 3 provides a method for removing carbon from a sample to be measured by in-situ transmission electron microscopy. The steps are as follows:
[0066] ① Take the SiC nanowires as the sample to be measured and load them into a corundum crucible that has been calcined to constant weight.
[0067] ② Place the crucible in a high-vacuum muffle furnace, evacuate the system to 10 Pa, and introduce high-purity argon (purity above 99.999%) at a speed of 50 ml / min to increase the pressure to 101 kPa; repeat the evacuation and argon introduction cycles 3 times to reduce the oxygen partial pressure level in the system.
[0068] ③ Under the condition of continuously purging with high-purity argon at a flow rate of 0.5 ml / min, heat the sample to be measured from room temperature (25°C) to 1200°C at a heating rate of 20°C / min, hold for 30 min, and then cool to room temperature (25°C) to obtain carbon-free SiC nanowires.
[0069] Comparative Example 1
[0070] Comparative Example 1 provides a kind of SiC nanowires, and the carbon of the SiC nanowires is removed by using the existing plasma cleaning technology: after ultrasonically dispersing the SiC nanowires in absolute ethanol, dropping them on an in-situ gas-phase chip, drying, and then using plasma to clean for 5 min.
[0071] To verify the progressiveness of the carbon removal method for the in-situ transmission electron microscopy (TEM) sample to be measured provided in the embodiments of the present application, the carbon-removed samples to be measured (SiC nanowires) obtained by the carbon removal methods provided in the embodiments and comparative examples were subjected to in-situ TEM detection, and the obtained in-situ TEM images are as shown in the attached Figures 2 to 5 as shown
[0072] The steps for in-situ TEM detection of the SiC nanowires in Example 3 are as follows: The carbon-removed SiC nanowires (samples to be measured) were ultrasonically dispersed in absolute ethanol and then dropped onto an in-situ gas-phase chip and dried; then, after plasma cleaning for 1 min, they were placed in an in-situ reaction chamber system; at a temperature of 900 °C, in-situ TEM observation was carried out to obtain in-situ TEM images.
[0073] The steps for in-situ TEM detection of the SiC nanowires in the comparative example are as follows: The SiC nanowires after plasma cleaning were placed in an in-situ reaction chamber system; at a temperature of 900 °C, in-situ TEM observation was carried out to obtain in-situ TEM images.
[0074] As can be seen from the attached Figures 2 to 5 it can be seen that:
[0075] For the carbon-removed sample to be measured obtained by the carbon removal method for the in-situ TEM sample to be measured in the embodiments of the present application, there is no longer any escaped organic matter deposited on the upper chip, and the sample morphology is clearly visible (as Figures 2 to 4 shown); while for the sample to be measured obtained by traditional plasma cleaning, a large amount of escaped organic matter is deposited on the upper chip, affecting the imaging effect of the in-situ TEM (as Figure 5 shown). Thus, it can be seen that for the carbon removal method for the in-situ TEM sample to be measured provided in the embodiments of the present application, under vacuum, the heating step volatilizes the organic matter in the sample to be measured, and the volatilized organic matter is extracted by vacuum (negative pressure), the high-temperature heat preservation step carbonizes the unvolatilized organic matter in the sample to be measured, and finally an inert gas is introduced to purge the residual organic matter and impurity gases (such as the gases generated by carbonization). The carbon removal method for the in-situ TEM sample to be measured provided in the embodiments of the present application can effectively remove the deep carbon deposits (organic matter) remaining during the preparation of the sample to be measured, with simple steps and low cost.
[0076] It should be noted that the present application is not limited to the above embodiments. The above embodiments are only examples, and embodiments having the same constitution and the same effect as the technical idea within the technical solution scope of the present application are all included in the technical scope of the present application. In addition, within the scope not departing from the gist of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other ways constructed by combining some constituent elements of the embodiments are also included in the scope of the present application.
Claims
1. A method for removing carbon from a sample to be tested by an in-situ transmission electron microscope, characterized in that: The steps include: Under vacuum conditions, the sample to be tested is subjected to a decarbonization treatment to obtain a decarbonized sample to be tested; The carbon removal process comprises a heating step, a heat preservation step and a temperature reduction step; The temperature of the heat preservation step is 800°C to 1200°C.
2. The in-situ transmission electron microscope sample removal method according to claim 1, characterized in that: In the heating step, the heating rate is 20°C / min to 100°C / min.
3. The method for removing carbon from a sample to be tested by an in-situ transmission electron microscope according to claim 2, characterized in that: In the heat preservation step, the heat preservation time is 30 minutes to 120 minutes.
4. The method for removing carbon from a sample to be tested by an in-situ transmission electron microscope according to any one of claims 1 to 3, characterized in that: The vacuum degree of the vacuum condition is 10 -3 Pa~10Pa.
5. The method for removing carbon from a sample to be tested by an in-situ transmission electron microscope according to claim 4, characterized in that: The vacuum degree of the vacuum condition is 10 -3 Pa~1Pa.
6. The method for removing carbon from a sample to be tested by an in-situ transmission electron microscope according to any one of claims 1 to 3 and 5, characterized in that: During the carbon removal process, background gas is continuously introduced for purging.
7. The method for removing carbon from a sample to be tested by an in-situ transmission electron microscope according to claim 6, characterized in that: The flow rate of the background gas is 0.5 ml / min to 50 ml / min.
8. The method for removing carbon from a sample to be tested by an in-situ transmission electron microscope according to claim 7, characterized in that: The background gas includes at least one of argon, nitrogen, helium and neon.
9. The in-situ carbon removal method for a sample to be tested by a transmission electron microscope according to any one of claims 1 to 8, characterized in that: The sample to be tested is a nano carbide, and the nano carbide includes at least one of SiC, ZrC, HfC, and TiC.
10. A method for removing carbon from a sample to be tested by an in-situ transmission electron microscope as claimed in any one of claims 1 to 9, and its use in the field of sample preparation for a transmission electron microscope.