Isomeric chromium atomic cluster and self-assembly method and application thereof

Abstract

The application discloses a kind of full same chromium atomic cluster and its self-assembly method and application, comprising the following steps: preparation Cr x NbSe2 Single crystal;Fix the single crystal to the sample holder, and fix the ceramic rod on the surface of the single crystal far from the sample holder on one side, place the assembled sample in an ultrahigh vacuum cavity, and impact the ceramic rod by external force to realize sample cleavage, then transfer the cleaved sample in situ to the scanning tunneling microscope cavity, and perform temperature reduction and surface morphology characterization. The application successfully realizes the self-assembly of large-area chromium atomic clusters by using single crystal cleavage technology, the cluster size is consistent and uniformly distributed, has extremely high chemical and structural stability, and the sample size can reach centimeter level, which lays a foundation for the application of magnetic atomic clusters in new generation semiconductor devices.

Description

Technical Field

[0001] This invention relates to the field of single crystal technology, and more specifically, to an isochromium atom cluster and its self-assembly method and application. Background Technology

[0002] Atomic clusters, as an important intermediate state between single atoms and bulk materials, exhibit immense potential in basic scientific research and cutting-edge technological applications due to their unique quantum effects and size dependence. Among them, magnetic atomic clusters, with their ultra-high specific surface area and significant surface effects, allow for precise control of magnetic properties by manipulating the size, composition, and structure of the clusters, making them promising for applications in spintronics, catalysis, energy, and biomedicine. Particularly in spintronics, magnetic atomic clusters are considered ideal candidate materials for next-generation spintronic devices and single-molecule magnets due to their ultra-high magnetic storage density. Furthermore, magnetic atomic clusters also exhibit potential qubit properties, which can be used for information storage and processing in quantum computing. In catalysis, magnetic clusters such as iron and cobalt have demonstrated excellent performance in key catalytic processes such as oxygen reduction and hydrogen evolution. Moreover, the efficient adsorption and degradation capabilities of magnetic clusters for pollutants are also attracting significant attention in environmental protection.

[0003] However, despite the enormous application potential shown by magnetic atomic clusters, their development still faces many challenges. Cluster stability is a significant issue limiting their practical application. Due to their small size and high surface energy, clusters are prone to oxidation, aggregation, or dissolution, thus affecting their performance. Current magnetic atomic cluster preparation technologies, including vapor-phase cluster condensation, laser evaporation, solution chemistry, and atomic beam deposition, still have bottlenecks in achieving high stability, large-scale production, and selective growth of single structures, severely restricting their application potential in semiconductor devices.

[0004] Therefore, developing a new method to prepare high-quality, large-area, and highly stable magnetic atomic clusters has become the key to solving this problem. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned defects in the prior art and provide an efficient method for preparing large-area identical chromium atom clusters and their self-assembly and application. By utilizing single-crystal cleavage technology, the self-assembly of large-area chromium atom clusters has been successfully achieved. The clusters are uniform in size and distribution, and have extremely high chemical and structural stability. The sample size can reach the centimeter scale, laying the foundation for the application of magnetic atom clusters in next-generation semiconductor devices.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A self-assembly method for isochromium atom clusters includes the following steps:

[0008] (1) Cr, Nb and Se are weighed according to the stoichiometric ratio x:1:2 and then mixed to obtain a mixture; wherein x is 14% to 33%;

[0009] (2) The mixture is pressed into a disc shape, then sealed in a quartz tube and preheated at 950℃~1050℃ for 22h~26h to obtain the pretreated precursor;

[0010] (3) The pretreated precursor and iodine are sealed again in a quartz tube and placed in a horizontal furnace. Crystal growth is carried out using the standard chemical vapor transport method. The temperatures of the hot end and cold end of the horizontal furnace are 1040℃~1060℃ and 990℃~1010℃, respectively. The growth time is >7d. CrxNbSe2 single crystal is obtained at the cold end.

[0011] (4) The Cr x The NbSe2 single crystal was fixed onto the sample holder, and the ceramic rod was fixed onto the Cr. x The assembled sample is obtained on the surface of the NbSe2 single crystal away from the sample holder;

[0012] (5) The assembled sample is placed in an ultra-high vacuum chamber and the ceramic rod is impacted by external force to achieve sample cleavage. Then the cleaved sample is transferred in situ to the scanning tunneling microscope chamber and cooled to 77K to complete the self-assembly of isochromium atom clusters.

[0013] Optionally, in step (4), the fixing uses EPO-TEK H20E silver paste; the fixing includes the following steps:

[0014] Weigh parts A and B of EPO-TEK H20E silver paste and mix them at a mass ratio of (0.9-1.1):1 (preferably 1:1). Stir well and let stand for 15-20 minutes, preferably 20 minutes.

[0015] Use the prepared silver paste to coat Cr x The NbSe2 single crystal was adhered to the sample holder and dried at 110°C–130°C for 25–30 minutes, preferably at 120°C for 30 minutes. Then, a ceramic rod was bonded to the Cr sample holder using a prepared silver paste. x The NbSe2 single crystal is dried on the surface away from the sample holder at a temperature of 110°C to 130°C for 25 min to 30 min, preferably at 120°C for 30 min.

[0016] Optionally, in step (5), the ultra-high vacuum conditions in the ultra-high vacuum cavity and the scanning tunneling microscope cavity are 5x10⁻⁶. -10 mbar ~ 1x10 -9 mbar.

[0017] Optionally, in step (4), the sample holder is made of stainless steel.

[0018] Optionally, the sample holder and the ceramic rod are respectively a sample holder and a ceramic rod that have been cleaned with anhydrous ethanol. Specifically, the sample holder and the ceramic rod are placed in anhydrous ethanol and ultrasonically cleaned for 15 minutes. After cleaning, they are picked up with tweezers and gently wiped with lint-free paper to remove residual ethanol from the surface.

[0019] Optionally, the diameter of the isochromium atom cluster is 0.76 nm, and the height is... And the cluster coverage is related to Cr x The chromium doping level is consistent in NbSe2 single crystals.

[0020] Optionally, in step (5), the tool used to strike the ceramic rod may be a rocker arm or other tools suitable for striking operations.

[0021] Optionally, in step (5), an external force impacts the ceramic rod in a direction perpendicular to the ceramic rod to achieve sample cleavage.

[0022] The present invention also discloses a self-assembly method for isochromium atom clusters as described above to obtain isochromium atom clusters.

[0023] The present invention also discloses a self-assembly method for isochromium atom clusters as described above, or the application of isochromium atom clusters as described above in next-generation semiconductor devices.

[0024] Implementing the embodiments of the present invention will have the following beneficial effects:

[0025] (1) The self-assembly method of isomeric chromium atom clusters provided by the present invention successfully prepares large-area ordered isomeric chromium atom clusters by in-situ cleaving of chromium-doped NbSe2 single crystals under ultra-high vacuum conditions. The atom clusters are spontaneously formed after cleaving under ultra-high vacuum and are highly ordered in distribution, effectively avoiding interference from impurities, and can obtain chromium atom clusters with extremely high purity.

[0026] (2) The chromium atom clusters obtained by the self-assembly method of the identical chromium atom clusters provided by the present invention remain stable in morphology after being placed in a vacuum environment for several hours, exhibiting extremely high structural stability, which is suitable for subsequent device processing and is beneficial to the application of magnetic clusters in the next generation of semiconductor devices.

[0027] (3) The single-crystal cleavage method used in this invention can cleave Cr with different chromium doping. x NbSe2 single crystals were used to obtain chromium atom clusters with different coverage; at the same time, the coverage and area size of the chromium atom clusters prepared by this invention can be controlled by the amount of chromium doping and the size of the single crystal sample.

[0028] (4) The self-assembly method of identical chromium atom clusters provided by the present invention has the advantage of realizing the self-assembly of large-area magnetic atom clusters. The sample can reach the centimeter scale, which provides an ideal material for the development of next-generation semiconductor devices. It is expected to be applied to information storage, transmission and processing and will play an important role in the post-Moore era.

[0029] In summary, this invention represents the first successful fabrication of large-area isomeric chromium atom clusters using single-crystal cleavage technology. Through in-situ cleavage of chromium-doped NbSe2 single crystals, scanning tunneling microscopy revealed the formation of large-area, ordered isomeric chromium atom clusters on the single crystal surface. Each cluster has a diameter of 0.76 nm and a height of [missing information]. The number and density of clusters can be controlled by the amount of chromium doping, and they maintain stable crystal structure and size even after long-term storage, making them suitable for subsequent device fabrication and applications. This invention overcomes the problems of existing technologies in the large-scale production of atomic clusters, selective growth of single structures, and high stability control. It expands new preparation processes, lays a solid foundation for the application of magnetic atomic clusters in next-generation semiconductor devices, provides a new experimental platform for studying cutting-edge scientific issues such as quantum materials and spintronics, and opens up new possibilities for developing high-performance, low-power functional devices. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the self-assembly of chromium atom clusters in Embodiment 1 of the present invention.

[0031] Figure 2 Cr for Test Example 1 of the present invention 0.14 Scanning tunneling microscopy (STM) image of chromium atom clusters on the surface of a NbSe2 single crystal.

[0032] Figure 3 Cr for Test Example 1 of the present invention 0.14 Three-dimensional image of chromium atom clusters on the surface of NbSe2 single crystal.

[0033] Figure 4 Cr for Test Example 1 of the present invention 0.14 Size calibration of chromium atom clusters on the surface of NbSe2 single crystals.

[0034] Figure 5 Cr for Test Example 2 of the present invention 0.14Transmission electron microscopy (TEM) and energy scattering X-ray spectroscopy (EDS) scan images of NbSe2 single crystals.

[0035] Figure 6 Cr in the embodiments of the present invention 0.14 Schematic diagram of NbSe2 single crystal size and cluster formation. Single crystal size is ~5mm.

[0036] Figure 7 Cr for Test Example 1 of the present invention 0.14 NbSe2 and Cr 0.33 STM image of chromium atom clusters on the surface of NbSe2 single crystal.

[0037] Figure 8 Cr in Example 1 of the present invention 0.14 STM image of chromium atom clusters on the surface of NbSe2 single crystal.

[0038] Figure 9 Cr in Example 1 of the present invention 0.14 Angle-resolved photoelectron spectroscopy (ARPES) image of NbSe2 single crystal. Detailed Implementation

[0039] The present invention will be further described below with reference to specific embodiments, but this does not limit the present invention in any way.

[0040] Example 1

[0041] The self-assembly method of isochromium atom clusters in this embodiment includes the following steps:

[0042] (1) Cr, Nb and Se were weighed and mixed in a stoichiometric ratio of 0.14:1:2. The resulting mixture was pressed into a disc shape, then sealed in a quartz tube and preheated at 1000℃ for 24h to obtain the pretreated precursor.

[0043] (2) The pretreated precursor and iodine were resealed in a quartz tube and placed in a horizontal furnace. Crystal growth was performed using the standard chemical vapor deposition method. The temperatures of the hot and cold ends of the horizontal furnace were 1050℃ and 1000℃, respectively. The growth time was >7 days. Cr was obtained at the cold end. 0.14 NbSe2 single crystal.

[0044] (3) Weigh part A and part B of EPO-TEK H20E silver paste, mix them at a mass ratio of 1:1, stir evenly and let stand for 20 minutes.

[0045] (4) After ultrasonically cleaning the sample holder and ceramic rod with anhydrous ethanol, use the silver paste obtained in step (3) to coat the Cr. 0.14The NbSe2 single crystal was adhered to the sample holder and dried at 120°C for 30 min on a heating stage; subsequently, the ceramic rod was bonded to the Cr using the silver paste obtained in step (3). 0.14 The NbSe2 single crystal sample holder was placed on one side of the sample holder and dried under the same conditions.

[0046] (5) Transfer the processed sample to an ultra-high vacuum chamber and place it under ultra-high vacuum conditions of 5 x 10⁻⁶. -10 Within the mbar sample processing chamber, sample cleavage is achieved by striking the ceramic rod with a rocker bar in a direction perpendicular to the ceramic rod (e.g., Figure 1 As shown), immediately after cleavage, the sample was transferred to an ultra-high vacuum condition of 5 x 10⁻⁶. -10 The scanning tunneling microscope chamber of mbar was cooled to 77K, and the Cr was cleaved. 0.14 In NbSe2 single crystals, chromium atoms spontaneously form large-area atomic clusters on the surface.

[0047] Example 2

[0048] The only difference between this embodiment and Embodiment 1 is that the chromium doping amount is 33%.

[0049] Test Example 1

[0050] Scanning tunneling microscopy test

[0051] Chromium atom clusters obtained in Examples 1 and 2 were measured using a low-temperature scanning tunneling microscope (LT-STM) manufactured by Scienta Omicron, Germany, with a testing temperature range of 4.5 K to 77 K. The morphology of the clusters could be measured using the scanning tunneling microscope. STM images at different scanning ranges show the chromium... 0.14 The chromium clusters obtained after cleaving NbSe2 single crystals are of uniform size and evenly distributed across the entire cleavage surface, such as... Figure 2 and Figure 3 As shown. The size of the cleavage planes in the sample determines the array size of the atomic clusters. The single crystal size of the cleavage is ~5 mm. Figure 6 (Left), which means that the size of the chromium atom cluster array prepared by single-crystal cleavage technology is also ~5mm. STM can accurately measure the size of the clusters, with a height of The diameter is 0.76 nm. Figure 4 STM can also measure cluster coverage. Cr 0.14 NbSe2 single crystal and Cr 0.33 The chromium clusters formed on the surface of NbSe2 single crystals were 14.16% and 36.78%, respectively, consistent with the chromium doping concentration. Figure 7This indicates that the coverage of chromium clusters increases with increasing chromium doping concentration. After being placed in a vacuum environment for 1 hour, the morphology of the chromium atom clusters remained stable, exhibiting extremely high structural stability. Figure 8 ).

[0052] Test Example 2

[0053] Scanning transmission microscopy test

[0054] The Cr used in Example 1 0.14 TEM measurements were performed on NbSe2 single crystals using a 120kV field emission transmission electron microscope (JEM-1400FLASH) manufactured by NJE Ltd., with a line resolution of 0.20nm and an accelerating voltage of 20-200kV. The TEM results indicate that chromium atoms are not located in the interlayer positions of NbSe2, but rather in the niobium atom layers. Figure 5 After single-crystal cleavage, chromium atoms migrate from the niobium atomic layer to the sample surface. Figure 6 right).

[0055] Test Example 3

[0056] Angle-resolved photoelectron spectroscopy

[0057] The Cr used in Example 1 0.14 ARPES analysis was performed on NbSe2 single crystals using an angle-resolved photoelectron spectrometer (ARPES) manufactured by Scienta Omicron, Germany. The analyzer model was DA30L, with an energy resolution of 150 meV and an angular resolution of 0.1°. The ARPES measurement results showed that, compared to intrinsic NbSe2 in the literature [Nature Communications 7, 11711 (2016)], Cr... 0.14 The band structure of the NbSe2 sample shifts downwards overall, indicating that chromium-doped Cr... x Electron doping was achieved in the NbSe2 single crystal sample. Figure 9 ).

[0058] Example 3

[0059] The self-assembly method of isochromium atom clusters in this embodiment includes the following steps:

[0060] (1) Cr, Nb and Se were weighed and mixed in a stoichiometric ratio of 0.20:1:2. The resulting mixture was pressed into a disc shape, then sealed in a quartz tube and preheated at 1050℃ for 22h to obtain the pretreated precursor.

[0061] (2) The pretreated precursor and iodine were resealed in a quartz tube and placed in a horizontal furnace. Crystal growth was performed using the standard chemical vapor transport method. The temperatures of the hot and cold ends of the horizontal furnace were 1040℃ and 990℃, respectively. The growth time was >7 days. Cr was obtained at the cold end. 0.20 NbSe2 single crystal.

[0062] (3) Weigh part A and part B of EPO-TEK H20E silver paste, mix them at a mass ratio of 1:1, stir evenly and let stand for 20 minutes.

[0063] (4) After ultrasonically cleaning the sample holder and ceramic rod with anhydrous ethanol, use the silver paste obtained in step (3) to coat the Cr. 0.20 The NbSe2 single crystal was adhered to the sample holder and dried at 120°C for 30 min on a heating stage; subsequently, the ceramic rod was bonded to the Cr using the silver paste obtained in step (3). 0.20 The NbSe2 single crystal sample holder was placed on one side of the sample holder and dried under the same conditions.

[0064] (5) Transfer the processed sample to an ultra-high vacuum chamber and place it under ultra-high vacuum conditions of 5 x 10⁻⁶. -10 Inside the mbar sample processing chamber, sample cleavage is achieved by striking the ceramic rod with a rocker arm in a direction perpendicular to the ceramic rod. Immediately after cleavage, the sample is transferred to an ultra-high vacuum condition of 5 x 10⁻⁶. -10 The scanning tunneling microscope chamber of mbar was cooled to 77K, and the Cr was cleaved. 0.20 In NbSe2 single crystals, chromium atoms spontaneously form large-area atomic clusters on the surface.

[0065] The effect of this embodiment is the same as that of Embodiment 1.

[0066] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for the self-assembly of isochromium atom clusters, characterized in that, Includes the following steps: (1) Cr, Nb and Se are weighed according to the stoichiometric ratio x:1:2 and then mixed to obtain a mixture; wherein x is 14%~33%; (2) The mixture is pressed into a disc shape, then sealed in a quartz tube and preheated at 950°C~1050°C for 22h~26h to obtain the pretreated precursor; (3) The pretreated precursor and iodine were sealed again in a quartz tube and placed in a horizontal furnace. Crystal growth was performed using the standard chemical vapor transport method. The temperatures of the hot and cold ends of the horizontal furnace were 1040°C~1060°C and 990°C~1010°C, respectively. The growth time was >7 days. Cr was obtained at the cold end. x NbSe2 single crystal; (4) The Cr x The NbSe2 single crystal was fixed onto the sample holder, and the ceramic rod was fixed onto the Cr. x The assembled sample is obtained on the surface of the NbSe2 single crystal away from the sample holder; (5) The assembled sample is placed in an ultra-high vacuum chamber and the ceramic rod is impacted by external force to achieve sample cleavage. Then the cleaved sample is transferred in situ to the scanning tunneling microscope chamber and cooled to 77 K. The self-assembly of isochromium atom clusters is observed using a scanning tunneling microscope. Chromium atoms are not located in the NbSe2 interlayer position, but in the niobium atom layer position; after single crystal cleavage, chromium atoms move from the niobium atom layer to the sample surface; The isochromium atom clusters have a diameter of 0.76 nm and a height of 1.47 Å, and their cluster coverage is similar to that of Cr. x The chromium doping level is consistent in NbSe2 single crystals; The morphology of the chromium atom clusters remained stable after being placed in a vacuum environment for 1 hour.

2. The self-assembly method for isochromium atom clusters according to claim 1, characterized in that, In step (4), the fixing uses EPO-TEK H20E silver paste; the fixing includes the following steps: Weigh parts A and B of EPO-TEK H20E silver paste and mix them at a mass ratio of (0.9~1.1):

1. Stir well and let stand for 15min~20min. Use the prepared silver paste to coat Cr x The NbSe2 single crystal was adhered to the sample holder and dried at 110℃~130℃ for 25min~30min. Then, a ceramic rod was bonded to the Cr sample holder using a prepared silver paste. x The NbSe2 single crystal was placed on the surface away from the sample holder and dried at 110°C to 130°C for 25 to 30 minutes.

3. The self-assembly method for isochromium atom clusters according to claim 1, characterized in that, In step (5), the ultra-high vacuum conditions in the ultra-high vacuum cavity and the scanning tunneling microscope cavity are 5 × 10. -10 mbar~1 x 10 -9 mbar.

4. The self-assembly method for isochromium atom clusters according to claim 1, characterized in that, In step (4), the sample holder is made of stainless steel.

5. The self-assembly method for isochromium atom clusters according to claim 1, characterized in that, The sample holder and the ceramic rod are respectively the sample holder and the ceramic rod after being cleaned with anhydrous ethanol.

6. The self-assembly method of isochromium atom clusters according to claim 1, characterized in that, In step (5), an external force impacts the ceramic rod in a direction perpendicular to the ceramic rod to achieve sample cleavage.

7. A self-assembly method for isochromium atom clusters as described in any one of claims 1-6, resulting in isochromium atom clusters.

8. A self-assembly method for isochromium atom clusters as described in any one of claims 1-6, or the application of isochromium atom clusters as described in claim 7 in next-generation semiconductor devices.

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