A method for strain-assisted co-production of large-size single-crystal metal foils

Abstract

The present application belongs to the technical field of metal foil single crystal technology, and particularly relates to a method for preparing large-size single crystal metal foil by strain coordination. The original metal foil is subjected to first annealing treatment to obtain a recrystallized polycrystal metal foil, the polycrystal metal foil is subjected to rolling treatment, the polycrystal metal foil is compressed in the thickness direction to obtain a strained metal foil, and the strained metal foil is subjected to second annealing treatment to obtain a large-size single crystal metal foil with low-index crystal faces. The method provided by the present application can be applied to metal foils with low purity (99% or above), and can obtain single crystal metal foils with low-index crystal faces. The method has strong universality, is simple, efficient, highly repeatable and low in cost, and can be widely used for preparing large-size single crystal metal foil substrates with low-index crystal faces and high quality, and has great application potential in the field of epitaxial preparation of novel two-dimensional photoelectric materials.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metal foil single crystal technology, and particularly relates to a method for preparing large-size single crystal metal foil through strain coordination. BACKGROUND

[0002] At present, most commercial metal foils are polycrystalline foils, however, single crystal metal foils have more excellent physical properties, such as better electrical and thermal conductivity, more excellent flexibility and ductility, and meanwhile, since single crystal metal foils have no grain boundaries and the surface atoms have consistent orientation, some individual crystal planes of certain metals have very small lattice mismatch with graphene [Cu(111): ~3-4%; Ni(111): ~1%; Co(0001): ~2%], which can be used as the epitaxial growth substrate of large-size single crystal new two-dimensional materials (graphene, hexagonal boron nitride, transition metal sulfide, etc.), such as copper foil, nickel foil, gold foil, etc. For example, graphene single crystal thin film is epitaxially grown on a Cu(111) single crystal substrate, single-layer MoS2 single crystal thin film of transition metal sulfide two-dimensional material is epitaxially grown on an Au(111) substrate, and multi-layer hexagonal boron nitride single crystal thin film and multi-layer graphene single crystal thin film are prepared on a Ni(111) substrate.

[0003] The traditional method for synthesizing single crystal metal is through bulk crystal growth (vertical pulling method or Bridgman method), a seed crystal of single crystal is used as the initial growth surface, and the material in a molten state is slowly pulled up through rotation, so as to realize the growth of single crystal. At present, there are also research works reporting that copper thin film is deposited on sapphire or copper foil is annealed to form single crystal foil, such as temperature gradient annealing, non-contact annealing and cyclic polishing annealing. These research works have achieved good results in the preparation of single crystal substrates.

[0004] However, the deposition of copper and other metal thin films on sapphire substrates faces problems such as high cost of sapphire substrates, rarity of magnetron sputtering equipment, and easy shrinkage of copper thin film to form discontinuous film in the process of high-temperature annealing; in the method of annealing single crystal metal foil, temperature gradient annealing needs precise temperature control experimental device, and both the method and non-contact annealing need the original copper foil to have a specific texture to be annealed into single crystal copper foil, and cyclic polishing annealing has a complex operation. The complexity of the operations, equipment or use of polycrystalline metal foils with specific textures involved in these researches hinders the wide application of the preparation method of single crystal metal.

[0005] How to improve the size of metal single crystal and reduce the preparation cost is of great significance to the application of various metal single crystals. Therefore, at present, the field of metal material research in China still needs to provide key technologies for large-scale preparation of metal single crystals. SUMMARY

[0006] The application aims to provide a method for preparing large-size single-crystal metal foil in coordination with strain, which can be applied to metal foils with low purity (more than 99%) to obtain single-crystal metal foils with low-index crystal faces, and has the advantages of wide applicability, simplicity, high efficiency, high repeatability and low cost, and can be widely used for preparing large-size single-crystal metal foil substrates with low-index crystal faces and high quality, and has great application potential in the field of epitaxial preparation of new two-dimensional photoelectric materials.

[0007] In order to achieve the above-mentioned purpose, the application provides the following technical scheme.

[0008] The application provides a method for preparing large-size single-crystal metal foil in coordination with strain, comprising the following steps.

[0009] The original metal foil is subjected to first annealing treatment to obtain a recrystallized polycrystal metal foil, the surface of the original metal foil is distributed with rolling stripes, and the wide edge of the original metal foil is greater than or equal to 0.5 cm.

[0010] The polycrystal metal foil is subjected to rolling treatment, the polycrystal metal foil is compressed in the thickness direction to obtain a strain metal foil.

[0011] The deformed metal foil is subjected to second annealing treatment, abnormal grain growth occurs, single-crystal growth is carried out, and a large-size single-crystal metal foil is obtained, and the large-size single-crystal metal foil is a single-crystal metal foil with a low-index crystal face.

[0012] Preferably, the original metal foil comprises a copper foil, a gold foil, a nickel foil, a silver foil, a cobalt foil, a platinum foil or a ruthenium foil.

[0013] Preferably, the purity of the original metal foil is greater than or equal to 99 wt%.

[0014] Preferably, the thickness of the original metal foil is greater than or equal to 10 microns, the width is 0.5-30 cm, and the length is 1-100 cm.

[0015] Preferably, the temperature of the first annealing treatment is 850-2000 DEG C, and the time is 0.5-12 h.

[0016] Preferably, the compression deformation amount is 0.1-15%.

[0017] Preferably, the temperature of the second annealing treatment is 850-2000 DEG C, and the time is 0.5-16 h.

[0018] Preferably, the first annealing treatment and the second annealing treatment are carried out in a reducing gas atmosphere, and the reducing gas comprises an inert gas and hydrogen.

[0019] The application provides a large-size single-crystal metal foil, which is prepared by the method.

[0020] Preferably, the single-crystal face of the large-size single-crystal metal foil is a 111 face or a 100 face.

[0021] The application provides a method for preparing a large-size single-crystal metal foil by strain synergy, which comprises the following steps: performing first annealing treatment on an original metal foil to obtain a recrystallized polycrystal metal foil, wherein the original metal foil has surface distribution of rolling stripes, and the width of the original metal foil is greater than or equal to 0.5 cm; performing rolling treatment on the polycrystal metal foil, so that the polycrystal metal foil is compressed in the thickness direction to obtain a strain metal foil; and performing second annealing treatment on the strain metal foil to cause abnormal grain growth and single-crystal growth to obtain a large-size single-crystal metal foil, wherein the large-size single-crystal metal foil is a single-crystal metal foil with a low-index crystal face. The method provided by the application first performs first annealing treatment on an original metal foil, then performs rolling treatment on the polycrystal metal foil obtained after the first annealing treatment to apply a certain amount of strain to the metal foil, stores energy by strain, and then performs second annealing treatment, so that the strain energy promotes abnormal grain growth, thereby obtaining a large-size single-crystal metal foil, which can be used as a growth substrate of a new two-dimensional material. The method provided by the application can be applied to a metal foil with low purity (more than 99 %), and a single-crystal metal foil with a low-index crystal face is obtained. The method has the advantages of strong universality, simplicity, high efficiency, high repeatability and low cost, and can be widely used for preparing a large-size single-crystal metal foil with a low-index crystal face and high quality, and has great application potential in the field of epitaxial preparation of new two-dimensional photoelectric materials.

[0022] Meanwhile, the method provided by the application is not limited by specific original texture of the original metal foil and precise temperature gradient of a tube furnace, and can be applied to treatment of various original metal foils with any size to obtain a large-size single-crystal metal foil by annealing, and has the characteristics of strong universality, simplicity, high efficiency and high repeatability, and has important practical application value.

[0023] Further in the present application, the purity of the original metal foil is ≥ 99wt%. Compared with the prior art, only high-purity (99.99% or more) commercial nickel foil can be used, and then stress treatment is directly applied, and then high-temperature annealing is performed, so that only single crystal nickel foil with high-index crystal faces can be obtained. The method provided by the present application is suitable for preparing large-size single crystal metal foil from metal foil with lower purity (99% or more). The present application first anneals the commercial metal foil (99% or more) to obtain a polycrystalline metal foil with a recrystallized grain distribution, then applies a roll stress treatment, and finally performs annealing treatment to obtain a single crystal metal foil with low-index crystal faces (such as 111 crystal faces or 100 crystal faces). The method provided by the present application is also suitable for metal foil with lower purity (99% or more). In the polycrystalline metal foil composed of multiple grains, the grain boundaries reach a state of balance and stability, and the surface energy is insufficient to drive the grain boundary migration to make the abnormal grains grow. However, the introduction of strain energy can break this balance, and the strain energy and the surface energy work together to make the grains with low-index crystal faces expand and migrate, thereby forming a large-size single crystal metal foil. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 Digital images and optical microscope images of polycrystalline copper foil prepared by the conventional annealing method and single crystal copper foil prepared by the roll annealing method in the present application;

[0025] Figure 2 XRD diffraction pattern of the single crystal copper foil prepared in the present application;

[0026] Figure 3 EBSD patterns of four random positions of the single crystal copper foil prepared in the present application;

[0027] Figure 4 Optical microscope images of graphene grown on the single crystal copper foil prepared in the present application;

[0028] Figure 5 Digital images and optical microscope images and XRD diffraction patterns of polycrystalline gold foil prepared by the conventional annealing method and single crystal gold foil prepared by the roll annealing method in the present application;

[0029] Figure 6 Optical microscope images of polycrystalline copper foil after direct roll annealing with a purity of 99% in the present application;

[0030] Figure 7 Operation flowchart and product characterization chart of the method in the present application. DETAILED DESCRIPTION

[0031] The present application provides a method for preparing a large-size single crystal metal foil by strain synergy, comprising the following steps:

[0032] carrying out a first annealing treatment on the original metal foil to obtain a recrystallized polycrystalline metal foil, the original metal foil having surface distributed rolling stripes, the width of the original metal foil being ≥0.5 cm;

[0033] carrying out a rolling treatment on the polycrystalline metal foil, the polycrystalline metal foil being compressed in the thickness direction to obtain a strain metal foil;

[0034] carrying out a second annealing treatment on the deformed metal foil to obtain a large-size single crystal metal foil by abnormal grain growth and single crystal growth, the large-size single crystal metal foil being a single crystal metal foil having a low-index crystal face.

[0035] In the present application, all the preparation raw materials / components are commercially available products well known to those skilled in the art, unless otherwise specified.

[0036] The present application carries out a first annealing treatment on the original metal foil to obtain a recrystallized polycrystalline metal foil, the original metal foil having surface distributed rolling stripes, the width of the original metal foil being ≥0.5 cm. In the present application, the original metal foil is preferably a commercially available metal foil, which is directly commercially available. The original metal foil preferably includes a copper foil, a gold foil, a nickel foil, a silver foil, a cobalt foil, a platinum foil, a tungsten foil, an iron foil or a ruthenium foil, more preferably a copper foil, a gold foil, a nickel foil or a silver foil. The purity of the original metal foil is preferably ≥99 wt%, and is particularly preferably 99 wt%.

[0037] In the present application, the thickness of the original metal foil is preferably ≥10 μm, more preferably 10-300 μm, further preferably 10-200 μm, and most preferably 20-120 μm. The width of the original metal foil is preferably 0.5-30 cm, and more preferably 1-20 cm. The length of the original metal foil is preferably 1-100 cm, and more preferably 1-40 cm. In a specific embodiment of the present application, the width of the original metal foil is 10 cm, the length is 30 cm, and the thickness is 30-100 μm.

[0038] In the present application, the first annealing treatment is preferably performed in a chemical vapor deposition tube furnace. The temperature of the first annealing treatment is preferably 850-2000°C, more preferably 900-1500°C, and particularly preferably 1050°C. The time of the first annealing treatment is 0.5-12 h, and more preferably 1-10 h. In the present application, the temperature rising time from room temperature to the temperature of the first annealing treatment is preferably 100-150 min. The first annealing treatment is preferably performed under normal pressure or negative pressure, and further preferably under normal pressure. The first annealing treatment is preferably performed in a reducing gas atmosphere, and the reducing gas preferably includes an inert gas and hydrogen. The inert gas is preferably argon. In the present application, the reducing gas is preferably a flowing gas, and the flow rate of the inert gas in the reducing gas is preferably 400-450 seem, and the flow rate of hydrogen is preferably 80-90 seem.

[0039] In the present application, the original metal foil is recrystallized in the first annealing treatment, and the surface is covered with grain boundaries, thereby obtaining a recrystallized polycrystalline metal foil.

[0040] After obtaining the polycrystalline metal foil, the polycrystalline metal foil is subjected to a roll pressing treatment in the present application, and the polycrystalline metal foil is compressed in the thickness direction, thereby obtaining a strained metal foil. In the present application, the roll pressing treatment preferably involves applying pressure to the surface of the polycrystalline metal foil using a press roller, thereby compressing the polycrystalline metal foil in the thickness direction. In the present application, the compression deformation amount is preferably 0.1-15%, more preferably 0.2-12%, and most preferably 0.5-10%. The compression deformation amount is the deformation amount of the polycrystalline metal foil in the thickness direction. In the present application, the roll pressing treatment preferably involves performing roll pressing of the polycrystalline metal foil in the form of self-rotation using an upper press roller and a lower press roller. The upper press roller and the lower press roller are located at the upper and lower surfaces of the polycrystalline metal foil. The moving speed of the polycrystalline metal foil during the roll pressing treatment is preferably 0.1-0.2 m / s.

[0041] After obtaining the strained metal foil, the present application performs a second annealing treatment on the strained metal foil to obtain a large-size single-crystal metal foil, which is a single-crystal metal foil with a low-index crystal face. In the present application, the second annealing treatment is performed in a chemical vapor deposition tube furnace. The temperature of the second annealing treatment is preferably 850-2000°C, more preferably 900-1800°C, most preferably 900-1500°C, and particularly preferably 1050°C. The time of the second annealing treatment is preferably 0.5-16h, more preferably 0.5-14h, most preferably 0.2-12h, and particularly preferably 6h. In the present application, the temperature rising time from room temperature to the temperature of the second annealing treatment is preferably 100-150min. The second annealing treatment is preferably performed under normal pressure or negative pressure, and further preferably under normal pressure. The second annealing treatment is preferably performed in a reducing gas atmosphere, and the reducing gas preferably includes an inert gas and hydrogen. The inert gas is preferably argon. The present application does not have special requirements for the volume ratio of the inert gas and hydrogen.

[0042] The method provided by the present application can effectively solve the problem that the existing method for preparing a single-crystal metal foil is limited by the texture and thickness of the original copper foil, and can efficiently and stably prepare a large-size single-crystal metal foil. For individual metal foils, the crystal face can also be regulated to obtain a single-crystal metal foil with a low-index crystal face, thereby realizing the epitaxial growth of a two-dimensional material single-crystal thin film.

[0043] The present application provides a large-size single-crystal metal foil, which is prepared by the method described in the above technical solution, and is a single-crystal metal foil with a low-index crystal face.

[0044] In the present application, the single-crystal crystal face of the large-size single-crystal metal foil is a 111 crystal face or a 100 crystal face.

[0045] In order to further illustrate the present application, the technical solutions provided by the present application are described in detail below in conjunction with examples, but they should not be understood as limiting the scope of protection of the present application.

[0046] The following examples are prepared according to the preparation process in the Figure 7 The following examples are prepared according to the preparation process in the

[0047] Example 1

[0048] This example provides a method for cooperatively preparing a large-size single-crystal metal foil by strain, which includes the following steps for copper foil:

[0049] A 10 cm wide, 30 cm long, 30 micrometer thick commercial copper foil with a purity of 99% was subjected to a first annealing treatment in a chemical vapor deposition tube furnace. The annealing treatment was performed under normal pressure in a reducing atmosphere containing a mixture of argon and hydrogen. The chemical vapor deposition tube furnace was purged with 400 sccm argon and 80 sccm hydrogen, and after the air was removed, the temperature was raised to 1050 °C within 100 min. The copper foil was subjected to isothermal annealing treatment under normal pressure for 1 h. The metal foil recrystallized, and the surface was covered with grain boundaries. A recrystallized polycrystalline copper foil was obtained.

[0050] The polycrystalline copper foil was then subjected to a rolling treatment in a biaxial rolling machine. The deformation amount of the copper foil was controlled by adjusting the distance between the two rolling shafts. The polycrystalline copper foil was then passed between the two rolling shafts at a speed of 0.1 m / s, and the deformation amount was between 1.5% and 2%.

[0051] The copper foil after the rolling treatment was subjected to a second annealing treatment. The chemical vapor deposition tube furnace was purged with 400 sccm argon and 80 sccm hydrogen, and after the air was removed, the temperature was raised to 1050 °C within 100 min. The copper foil was subjected to isothermal annealing treatment under normal pressure for 6 h. After natural cooling, a large-size single-crystal copper foil was obtained.

[0052] Comparative Example 1

[0053] The method was basically the same as that of Example 1, except that the rolling treatment step between the first annealing and the second annealing in Example 1 was omitted. In the method provided in this comparative example, no strain was applied, and a polycrystalline copper foil was obtained, and no large-area single-crystal growth occurred.

[0054] Digital images and optical microscope images of the polycrystalline copper foil prepared by the conventional annealing method in Comparative Example 1 and the single-crystal copper foil prepared by the annealing-rolling-reannealing method in Example 1 are shown in FIGS. 1 and 2, respectively. Figure 1 In FIG. 1, Figure 1 (a) is a digital image of the polycrystalline metal foil prepared in Comparative Example 1, Figure 1 (f) is a digital image of the large-size single-crystal copper foil prepared in Example 1, Figure 1 (b), (c), (d), and (e) are optical microscope images of the polycrystalline metal foil prepared in Comparative Example 1, Figure 1 (g), (h), (i), and (j) are optical microscope images of the large-size single-crystal copper foil prepared in Example 1. Figure 2 is an XRD diffraction pattern of the single-crystal copper foil prepared in Example 1, and specifically, Figure 2 the four XRD diffraction curves in Figure 1 (f) are the test results at four random positions in Figure 2It can be seen that the test results of any position of the large-size single-crystal copper foil prepared in Example 1 are 111 crystal face diffraction peaks, which can more illustrate the single-crystal property of the large-size copper foil prepared in Example 1. Figure 3 The EBSD patterns of four random positions of the single-crystal copper foil prepared in Example 1 are shown in FIG. 2. Figures 1 to 3 It reflects the single-crystal property of the large-size single-crystal copper foil prepared in Example 1. Figure 4 The optical microscope image of the graphene grown on the large-size single-crystal copper foil prepared in Example 1 is shown in FIG. 3, wherein the graphene is grown by chemical vapor deposition method, that is, the single-crystal copper foil is heated to 1050℃ under the atmosphere of 250sccm argon and 20sccm hydrogen, 3sccm methane is introduced for 10min. Figure 4 It can be seen that the large-size single-crystal copper foil prepared in Example 1 can realize epitaxial growth of two-dimensional material single-crystal thin film.

[0055] Example 2

[0056] The method for preparing the large-size single-crystal gold foil in the present example is different from that in Example 1 in that the commercial copper foil in Example 1 is replaced by a commercial gold foil, the thickness of the gold foil is 100μm, the second annealing temperature is 1050℃, and the rest of the steps and parameters are the same as those in Example 1.

[0057] The XRD diffraction pattern and the optical microscope image of the large-size single-crystal gold foil prepared in the present example are shown in FIG. 4. Figure 5 As shown in the right image in FIG. 4, the crystal face of the large-size single-crystal gold foil prepared in the present example is 111 crystal face.

[0058] Comparative Example 2

[0059] The method in the present comparative example is basically the same as that in Example 2, except that the rolling treatment step between the first annealing and the second annealing in Example 2 is omitted. In the method provided in the present comparative example, no strain is applied, and a polycrystal gold foil is obtained, without large-area single-crystal growth.

[0060] The digital image and the optical microscope image and the XRD diffraction pattern of the polycrystal gold foil prepared by the conventional annealing method involved in Comparative Example 2 and the single-crystal gold foil prepared by the first annealing-rolling-the second annealing method in Example 2 are shown in FIG. 5. Figure 5 As shown in FIG. 5, Figure 5 The XRD diffraction pattern and the optical microscope image of the polycrystal gold foil prepared in Comparative Example 2 are shown in the left image in FIG. 5. Figure 5 The XRD diffraction pattern and the optical microscope image of the large-size single-crystal gold foil prepared in Example 2 are shown in the right image in FIG. 5. Figure 5 It can be seen that the crystal face of the large-size single-crystal gold foil prepared in Example 2 is 111 crystal face, while the product prepared in Comparative Example 2 is a polycrystal gold foil.

[0061] Comparative Example 3

[0062] The method provided by Comparative Example 3 is basically the same as that of Example 1, except that the 99% purity commercial copper foil of Example 1 is omitted from the first annealing treatment, and is directly subjected to the rolling treatment and the second annealing treatment, and the optical microscope image of the obtained metal foil product is as shown in Figure 6 . Figure 6 The optical microscope image of the polycrystalline copper foil after the direct rolling annealing of the 99% purity commercial copper foil in Comparative Example 3. It can be seen from Figure 6 that the 99% purity commercial copper foil cannot obtain a single crystal copper foil after direct rolling annealing, but only a polycrystalline copper foil.

[0063] From the above examples, it can be seen that the original metal foil is subjected to a first annealing treatment, the original metal foil is recrystallized to obtain a polycrystalline metal foil, the polycrystalline metal foil is subjected to a rolling treatment, the polycrystalline metal foil is compressed in the thickness direction to obtain a strained metal foil, and the strained metal foil is subjected to a second annealing treatment to obtain a large-size single crystal metal foil with a low-index crystal face. The method provided by the present application can be adapted to a metal foil with lower purity (99% or more), and a single crystal metal foil with a low-index crystal face is obtained. The method has strong universality, is simple and efficient, has high repeatability, and has low cost, and can be widely used for preparing a large-size high-quality single crystal metal foil with a low-index crystal face, and has great application potential in the field of epitaxial preparation of new two-dimensional photoelectric materials.

[0064] Although the above examples have made a detailed description of the present application, it is only a part of the embodiments of the present application, but not all the embodiments, and other embodiments can be obtained according to the present embodiments without creativity, and these embodiments all belong to the protection scope of the present application.

Claims

1. A method for strain-coordinated fabrication of large-size single-crystal metal foil, characterized in that, Includes the following steps: The original metal foil is subjected to a first annealing treatment to obtain a recrystallized polycrystalline metal foil. The surface of the original metal foil is distributed with rolling stripes, the width of the original metal foil is ≥0.5cm, and the purity of the original metal foil is ≥99wt%. The recrystallized polycrystalline metal foil is subjected to roll forming, in which the polycrystalline metal foil undergoes compressive strain in the thickness direction to obtain a strained metal foil, wherein the compressive strain deformation is 0.1% to 15%. The strained metal foil is subjected to a second annealing treatment, which causes abnormal grain growth and single crystal growth to obtain a large-size single crystal metal foil. The large-size single crystal metal foil is a single crystal metal foil with a low index crystal plane.

2. The method according to claim 1, characterized in that, The original metal foils include copper foil, gold foil, nickel foil, silver foil, cobalt foil, platinum foil, tungsten foil, iron foil, or ruthenium foil.

3. The method according to claim 1 or 2, characterized in that, The original metal foil has a thickness ≥10μm, a width of 0.5~30cm, and a length of 1~100cm.

4. The method according to claim 1, characterized in that, The first annealing treatment is performed at a temperature of 850~2000℃ for a time of 0.5~12h.

5. The method according to claim 1, characterized in that, The second annealing process is carried out at a temperature of 850~2000℃ for a time of 0.5~16h.

6. The method according to claim 1, 4, or 5, characterized in that, The first and second annealing processes are carried out in a reducing gas atmosphere, which includes an inert gas and hydrogen.

7. A large-size single-crystal metal foil, characterized in that, The large-size single-crystal metal foil is prepared by the method according to any one of claims 1 to 6, wherein the large-size single-crystal metal foil is a single-crystal metal foil with a low-index crystal plane.

8. The large-size single-crystal metal foil according to claim 7, characterized in that, The large-size single-crystal metal foil has a single-crystal plane of 111 or 100.

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