CN107572476B - A method of preparing metal micro-nano structure - Google Patents

Abstract

The invention discloses a kind of methods for preparing metal micro-nano structure, the metal includes pure metal or metal alloy, metal or metal alloy is heated first, then apply the mold that the metal or metal alloy indentation of heating is had micro nano structure by load, to form the composite construction of the mold and metal or metal alloy with micro nano structure；Then the mold in composite construction is removed, to form metal or metal alloy micro nano structure.The present invention applies thermoplasticity stamped method to prepare at a temperature of lower than material melting point less than the metal or metal alloy micro nano structure of metal grain size for the first time: preparation method is simple, at low cost, yield is high, precision is high and size is controllable；The metal nanometer line array prepared has significant Raman enhancement effect, has a wide range of applications.

Description

A kind of method for preparing metal micro-nano structure

technical field

The invention relates to a method for preparing a metal micro-nano structure, and belongs to the field of nano-manufacturing.

Background technique

Micro- and nano-sized structured materials can significantly improve the properties of materials in optical, electrical, magnetic, and catalytic fields, and thus have a wide range of applications in batteries, catalysis, optics, sensing, and surface physicochemistry. For example, platinum nanomaterials have been widely used in automobile exhaust purification, petrochemical, fuel cells and other fields due to their high catalytic properties. The amount of platinum used for catalysts in the world is about 100 tons per year, with a value of more than 4 billion US dollars. The surface plasmon optics of gold, silver, copper and other metal nanostructures have a wide range of applications in the fields of photocatalysis, nano-integrated photonics, optical sensing, biomarkers, medical imaging, solar cells, and surface-enhanced Raman spectroscopy (SERS). application prospects.

At present, the preparation methods of metal or metal alloy micro-nanostructures reported in the literature are mainly divided into two categories. One is the "top-down" method of obtaining micro-nanostructures from bulk materials, including:

a) Use pulsed laser to selectively process the surface of materials to obtain micro-nano structures, such as the patent of US Patent Publication No. US20140154526A1, published on April 1, 2014, and the invention name is "Femtosecond laser pulsesurface structuring methods and materials resulting therefrom" , which is based on the locally generated heating, melting and evaporation effects when a high-energy laser beam irradiates a surface. The main disadvantages of this patent are that high-power laser is required, the energy consumption is large, the size of the prepared micro-nano structure pattern is limited by the size of the laser beam spot (generally more than 1 micron), and it is difficult to process a large aspect ratio. Or micro-nano structures with slenderness ratios.

b) The macro-scale filaments (or filament bundles) of metals or metal alloys are drawn above their melting point temperature to reduce the diameter of the filaments, such as US Patent Publication No. US 8658880 B2, published in 2014 On February 25, the patent titled "Methods of drawing wire arrays", and the US patent publication number US 9245671B2, the publication date was January 26, 2016, and the invention title was "Electrically Isolated, High Melting Point, Metal Wire Arrays" And Method Of Making Same" patent. The main disadvantage of the above patents is that the equipment and process are complicated, and it is necessary to prepare filaments with a uniform diameter in the sub-millimeter order first. In particular, the drawing process occurs above the melting point temperature. Since the viscosity of the material is very low and the flow resistance is small at this time, any minor disturbances from initial defects such as uneven diameter, drawing speed or the environment in which the filament is located, such as temperature, are possible. This leads to the occurrence of locally unstable fractures (Reynolds instability).

c) Injection of molten metal into nanopores under high pressure. For example, the US patent publication number is US 6231744 B1, the publication date is May 15, 2001, and the invention title is "Process for fabricating an array of nanowires". This patent needs to melt the metal first, and then press the molten metal into the nanopores under high pressure and vacuum environment, so generally only low melting point metal nanostructures can be prepared; and due to the flow resistance and pore size of the molten metal in the nanopores is inversely proportional to the 4th power, so it is difficult to prepare nanowires with high aspect ratio.

d) For a special class of amorphous metal alloy materials, thermoplastic nanoimprinting is performed between their glass transition temperature (Tg) and crystallization temperature (Tx) to obtain nanostructures, as published on February 12, 2009 in Paper titled "Nanomoulding with amorphous metals" in Nature, Vol. 457, pp. 868-872, and "General nanomoulding with bulk metallic glasses" in Nanotechnology, Vol. 26, Issue 14, March 18, 2015 "Thesis. The main disadvantage of the above methods is that the viscosity of amorphous alloys is generally still higher than 10 ⁵ MPa·s between the glass transition temperature and the crystallization temperature, so it is still challenging to perform nanoimprinting on amorphous metal alloys with poor formability. The currently reported imprintable amorphous metal alloys are limited to platinum-based, palladium-based, gold-based, and zirconium-based amorphous alloy systems with excellent formability. On the other hand, since the amorphous alloy is a metastable structure, the process between its glass transition temperature and crystallization temperature is time-limited, so it is generally difficult to process a high slenderness ratio. micro-nano structures.

The other is the "bottom-up" method of preparing micro-nano structures, mainly including:

a) Liquid phase synthesis. For example, the Chinese patent publication number is CN1727523, the publication date is February 1, 2006, and the invention title is "Method for liquid phase synthesis of one-dimensional ultra-long metallic copper nanowires". The Chinese patent publication number is CN103540995A, and the publication date is 2014. On January 29, 2009, the patent titled "A method for liquid-phase synthesis of germanium nanowires" was published, and published on Angew.Chem.Int.Ed. on December 3, 2009, Volume 48, No. 1, Paper titled "Shape-Controlled Synthesis of Metal Nanocrystals: Simple Chemistry Meets ComplexPhysics?" As the most widely used nano-metal synthesis method at present, this method relies on the decomposition or degradation of metal-containing precursor compounds and nucleation to grow nanostructures. Nanostructures are difficult to disperse.

b) Thermal evaporation method. For example, the US patent publication number is US 6808605 B2, the publication date is October 26, 2004, the invention title is "Fabrication method of metallic nanowires", and it was published on February 17, 2003 in Adv.Mater. Journal No. 15 Volume 4, paper titled "A novel method for preparing coppernanorods and nanowires". This method generally requires first forming a catalytic metal layer on the substrate, and then placing the substrate in an evaporation furnace for autocatalytic reaction, or directly depositing metal vapor on the surface of the substrate, the main disadvantage is that the equipment is expensive and the process is complicated.

c) Sputtering method. For example, the paper titled "Hybridnanocolloids with programmed three-dimensional shape and materialcomposition" was published in the Nat.Mater. Journal Volume 12 on June 23, 2013. The main disadvantage of this method is that the equipment is expensive, it is difficult to prepare micro-nanostructures with high aspect ratio, and the prepared metal nanostructures have the problem of poor compactness and thus poor mechanical properties.

d) Electrodeposition method. For example, the Chinese patent publication number is CN102251232A, the publication date is November 23, 2011, and the invention title is "a method for preparing silver nanowire arrays in an ordered porous alumina template", and the Chinese patent publication number is CN 104152958 A. The publication date is November 19, 2014, and the invention title is "Method for preparing multilayer nanowires using template electrochemical synthesis technology". The main disadvantage of the above patents is that it is difficult to deposit nanomaterials in long template holes or small diameter template holes.

e) Chemical deposition method, which is the most commonly used method at present. For example, the US Patent Publication No. US 7217650B1, the publication date is May 15, 2007, and the invention name is "Metallic nanowire interconnections forintegrated circuit fabrication", and the US Patent Publication No. US 7344753 B2, the publication date is May 2008 On the 18th, a patent named "Nanostructures including a metal" was invented. The main disadvantages of the above-mentioned patents are that they need to rely on organometallic compounds, and the organometallic compounds need to be vaporized and introduced onto the substrate, and the equipment is expensive and the process is complicated.

f) The metal nanowires are prepared by a method in which a metal film with a high initial compressive stress is diffused on a metal substrate with a higher melting point to release the compressive stress. For example, the U.S. Patent Publication No. is US 20040146710A1, the publication date is July 29, 2004, and the invention title is "Metallic nanowire and method of making the same", and the US Patent Publication No. US 20040146735A1, the publication date is July 2004. On March 29, the patent named "Metallicnanowire and method of making the same" was invented. The main disadvantage of this method is that metal composite films with different melting points need to be prepared, and an initial high-pressure stress state needs to be formed in the upper layer film; in addition, the method of releasing the compressive stress through the diffusion of low-melting metal atoms to form nanowires cannot prepare nanowires with variable sizes. Controlled and uniformly distributed nanowire arrays.

To sum up, the previous preparation process of metal or metal alloy micro-nano structure is often complicated, or the size of the prepared micro-nano structure is limited and difficult to control, or the equipment is expensive, the cost is high, and the output is low. Thermoplastic nanoimprinting provides an inexpensive, fast and ordered method for the preparation of micro-nanostructures, but it is currently limited to glassy materials such as polymers and amorphous metal alloys. For a long time, it was believed that crystalline metals or alloys were not able to prepare micro-nanostructures smaller than the metal grain size by thermoplastic nanoimprinting below the melting temperature due to the limitation of their intrinsic grain size. For details, see December 2014. Paper titled "Large-scalenanoshaping of ultrasmooth 3D crystalline metallic structures" published in Science, Vol. 346, No. 6215, Feb. 12, 2009, and Nature, Vol. 457, p. 868, Feb. 12, 2009 -872. Thesis titled "Nanomoulding with Amorphous Metals".

SUMMARY OF THE INVENTION

Aiming at the defects of the prior art, the present invention applies the thermoplastic imprinting method for the first time to prepare metal or metal alloy micro-nano structures smaller than the metal grain size at a temperature lower than the melting point of the material: firstly heat the metal or metal alloy, and then apply a load to The heated metal or metal alloy is pressed into the mold with the micro-nano structure to form the mold with the micro-nano structure and the composite structure of the metal or metal alloy; then the mold in the composite structure is removed to form the metal or metal alloy micro-nano structure.

The technical solutions provided by the present invention are as follows:

A method for preparing metal micro-nano structure, comprising the following steps:

(1) Heating the metal and the mold with the micro-nano structure to a temperature T, where 0.5T _m ≤ T < T _m , T represents the absolute temperature, and T _m represents the melting point temperature of the metal according to the absolute temperature scale;

(2) applying a load to press the metal with a temperature of T into the mold to obtain a composite structure formed by the mold and the metal;

(3) removing the mold to obtain metal with micro-nano structure;

The metal is any pure metal or alloy of In, Ge, Sn, Bi, Pb, Zn, Al, Cu, Au, Ag, Pt and Pd.

The characteristic scale of the micro-nano structure is 1 nm-50 μm.

The characteristic scale of the micro-nano structure is 1 nm-100 nm.

The characteristic scale of the micro-nano structure is 100 nm-50 μm.

The mold material with micro-nano structure is silicon, silicon oxide, aluminum oxide or other inorganic oxides.

The removal method described in step (3) is chemical corrosion.

The step (3) specifically includes the following steps: placing the composite structure formed by the mold and the metal in an alkali solution or an acid solution, heating, and after the mold is completely corroded, then soaking and rinsing with deionized water and anhydrous ethanol in turn to obtain Metals with micro-nano structures.

The metal is in bulk, flake or granular form.

The inventive principle of the present invention is specifically as follows:

The invention utilizes that the metal or metal alloy atoms and the defect fluidity (or diffusion motion) thereof are significantly enhanced under the action of high temperature and high pressure, so that the metal or metal alloy can precisely replicate the micro-nano structure in the mold. Without loss of generality, take a mold with columnar nanoholes as an example, the diameter of the nanohole is denoted as d, and the length L of the metal or metal alloy material pressed into the hole under constant stress conditions is investigated. It is obvious that L can be generally expressed as a function of temperature T, constant stress σ, pore diameter d and time t.

L=f(σ,T,t,d) (1)

Applying the classical Norton-Bailey power law relation, we have

L=L ₀ +Aσ ⁿ t ^m (2)

Among them, L ₀ represents the length that the material has flowed into the hole when the load reaches the constant stress σ, which generally depends on the pore diameter, temperature, constant stress value, and loading rate; the constant A depends on the temperature, pore diameter and material parameters of the material such as shear modulus Wait. Therefore, for the examples of preparing metal or metal alloy micro-nanostructures under constant temperature and constant load conditions, the relationship between the length of the prepared nanowires and the hot pressing time can be simply expressed as

L=L ₀ +Bt ^m (3)

The present invention has the following advantages and beneficial effects:

(1) the preparation method of the present invention is simple, low in cost, high in yield, high in precision and controllable in size;

(2) The characteristic size of the micro-nano structure prepared by the present invention is small and the slenderness ratio can be up to 200-400;

(3) The metal or metal alloy micro-nano structures prepared by the present invention have wide application prospects; for example: the application of Ag, Cu and other nanoparticles with good electrical conductivity in the field of microelectronics; Drug resistance and super-permeability in medical applications; surface plasmon resonance properties of nanoparticles such as Au, Ag, and Cu in biochemical sensing, surface-enhanced Raman spectroscopy, biomedicine, and nanophotonics The application of platinum group metals such as Pt, Pd and Cu and corresponding alloys as high-efficiency catalysts in the fields of fuel cells and petrochemicals.

Description of drawings

Fig. 1 is a schematic diagram of the method of the present invention; wherein, 1 is a metal or metal alloy block, and 2 is a mold having a micro-nano structure.

FIG. 2 is a schematic flow chart of the preparation of metal micro-nano structures according to the present invention.

3 is a diagram of the Au nanowire array prepared in Example 1 of the present invention, and a transmission electron microscope (TEM) high-resolution image of a single Au nanowire with a diameter of about 8 nm, the lattice of the prepared Au nanowire can be clearly seen orientation;

Fig. 4 is a graph showing the effect of hot pressing temperature on the length of prepared Au nanowires;

Fig. 5 is a graph showing the effect of hot pressing time on the length of prepared Au nanowires;

Fig. 6 is the Ag nanowire array diagram prepared by the present invention;

Fig. 7 is the Bi nanowire array diagram prepared by the present invention;

Fig. 8 is the Pt nanowire array diagram prepared by the present invention;

Fig. 9 is the Pd nanowire array diagram prepared by the present invention;

Figure 10 is an array diagram of metal alloy Au ₈₀ Si ₂₀ nanowires prepared by the present invention;

Figure 11 is an array diagram of metal alloy Au ₇₄ Co ₂₆ nanowires prepared by the present invention;

Figure 12 is a diagram of an array of metal alloy Ag ₃ In nanowires prepared by the present invention;

Fig. 13 is the metal alloy Ag ₅₅ Al ₄₅ nanowire array diagram prepared by the present invention;

Fig. 14 is the metal alloy Ag ₇₅ Ge ₂₅ nanowire array diagram prepared by the present invention;

Figure 15 is an array diagram of metal alloy Cu _34.7 Zn _3.0 Sn _62.3 nanowires prepared by the present invention;

16 is a diagram of a metal alloy ordinary copper wire nanowire array prepared by the present invention;

Figure 17 is a diagram of the micro-nano secondary structure of Ag prepared by the present invention, Figure 17 (a) is a diagram of the secondary structure observed under a smaller magnification, Figure 17 (b) is a partial enlarged diagram of Figure 17 (a), with Clearer observation of micro-nano secondary structure;

FIG. 18 is a diagram of the Au nano-multilevel structure prepared by the present invention, FIG. 18(a) is a diagram of the nano-level structure observed under a smaller magnification, and FIG. 18(b) is a partially enlarged part of the smaller size of the multilevel structure;

Figure 19 is a Raman spectrum diagram comparing Crystal Violet (CV) molecules placed on the Au nanowire array prepared by the present invention and the bulk Au surface without nanowires: Figure 19(a) is the bulk Au surface without nanostructures Figure 19(b), Figure 19(c), Figure 19(d) show the significant enhancement of CV molecular Raman spectra by Au nanowire arrays with nanowire diameters of 200 nm, 90 nm, and 35 nm, respectively. effect.

Detailed ways

Presently preferred embodiments and methods of the invention, which constitute the present inventors' preferred modes for practicing the invention, will now be described in greater detail with reference to the accompanying drawings. However, the embodiments disclosed herein are merely exemplary of the invention, and thus the disclosed implementation details are provided only as a representative basis for the invention and should not be construed as limitations of the invention. The present invention may encompass schemes and methods of varying implementation details.

Example 1

1) The Au block of 43mg was weighed and placed on the porous anodic aluminum oxide (hereinafter referred to as AAO mould: purchased from Hefei Puyuan Nanotechnology Co., Ltd.) mould with a through hole diameter of about 20nm;

2) Use a high-temperature furnace to heat two flat plates placed opposite each other, and the two flat plates are connected to a device that can apply a load (in all embodiments of the present invention, the two flat plates are respectively connected to the upper and lower clamps of the testing machine). Set the target temperature of the plate to 940K (the temperature of the plate is monitored by the temperature control system of the high temperature furnace);

3) After the plate temperature reaches the predetermined temperature and is stable, place the stacked Au blocks/AAO molds together between the two plates, wait for the Au blocks to be heated, and control the two plates at a constant displacement loading rate through the testing machine control software. 0.5mm/min for relative movement, when the load reaches 20KN, it is completely unloaded at a rate of 14.4mm/min;

4) Take out the sample, use 1-3mol/L acid or alkaline aqueous solution (if no special instructions, in all embodiments of the present invention, all use potassium hydroxide (KOH) aqueous solution) and under the temperature condition of room temperature to 100 degrees Celsius Corrode the AAO mold, and after the AAO is completely corroded, soak and rinse the sample with deionized water, acetone or absolute ethanol in turn (if there is no special instruction, in the following examples, the concentration and corrosion temperature within the above-mentioned range are selected to completely corrode the AAO mold. or silicon mold, and use the same process steps to clean the sample);

5) Using a scanning electron microscope (SEM) to observe the surface of the cleaned sample, the nanowire array on the surface of Au can be clearly seen (FIG. 3).

Example 2

In order to study the influence of holding time, a key preparation process parameter in the present invention, five Au samples of the same mass were weighed in this example. Except for the different holding times of the samples under constant load, all other process conditions were the same. To investigate the relationship between the length of the prepared Au nanowires and the retention time. The specific process steps are as follows:

1) Weigh 61.8 ± 0.5 mg of Au block and place it on an AAO mold with a through hole diameter of about 200 nm;

2) Set the target temperature of the plate to 773K. When the plate temperature reaches the set temperature, place the stacked Au block/AAO mold between the two plates;

3) After the Au block is heated, the two plates are controlled to move relative to each other at a constant force loading rate of 1KN/s through the testing machine control software. The rate of /s is completely unloaded;

4) Take out the sample, place it in KOH aqueous solution and completely corrode AAO at a temperature of 85 degrees Celsius, then soak and rinse with deionized water and absolute ethanol in turn;

5) Observe and measure the length of the nanowires in the central area of the sample with SEM.

According to the results of the nanowire length and force holding time measured experimentally (black dots in Fig. 4(a)), the above experimental data are nonlinearly fitted by equation (3), and the fitting result is: L=1269.2+434.8 ×t _^0.35 (solid line in Fig. 4(a)), where the length of the nanowire is in nm and the time in s. And define the apparent strain rate as follows: Then, the apparent strain rates at different times can be obtained according to the fitting results ( FIG. 4( b )). It can be seen that in this embodiment, the apparent strain rates can reach the order of 10 ^-3 s ^-1 . This example shows that nanowire arrays of different lengths can be precisely controlled and fabricated by controlling the force dwell time.

Example 3

In order to study the influence of the key preparation process parameter in the present invention, the hot-pressing temperature, five Au samples of the same quality were weighed in this example. Except for the different hot-pressing temperatures of the samples, all other process conditions were The relationship between the length of Au nanowires and the hot pressing temperature. The specific process steps are as follows:

1) Weigh 29.5±0.5mg of Au block and pre-press at about 688K into a thin sheet with a thickness of 0.35±0.05mm; place the pre-pressed Au sheet on an AAO mold with a through hole diameter of about 100nm;

2) Set different plate target temperatures for the 5 samples respectively, when the plate temperature reaches the set temperature, place the stacked Au flakes/AAO molds between the two plates;

3) After the Au sheet is heated, the two plates are controlled to move relative to each other at a constant force loading rate of 0.5KN/s through the testing machine control software. completely uninstall;

4) Take out the sample, place it in KOH aqueous solution and completely corrode AAO at a temperature of 85 degrees Celsius, then soak and rinse with deionized water and absolute ethanol in turn;

5) Observe and measure the length of the nanowires in the central area of the sample with SEM.

The results of the experimentally measured nanowire length and hot-pressing temperature are shown as black dots in Fig. 5 . It can be seen that with the increase of the hot-pressing temperature, the length of the prepared Au nanowires first increases in the investigated temperature range, then decreases slightly, and finally continues to increase. The overall trend of nanowire length increasing with temperature can be explained by the fact that increasing temperature reduces the activation energy barrier of atoms (or defects), while the behavior around 550 degrees Celsius (i.e. 823 K) suggests that the The dominant creep mechanism has changed significantly.

Example 4

1) Weigh 0.14g Ag block and place it on an AAO mold with a pore diameter of about 200nm;

2) The target temperature of the set plate is 980K, when the plate temperature reaches the set temperature, place the stacked Ag block/AAO mold between the two plates;

3) After the Ag block is heated, the two plates are controlled by the testing machine control software to move relative to each other at a constant displacement loading rate of 18mm/min. completely uninstall;

4) Take out the sample, place it in KOH aqueous solution and completely corrode AAO at a temperature of 85 degrees Celsius, then soak and rinse with deionized water and absolute ethanol in turn;

5) The morphology of the nanowires on the surface of the sample was observed by SEM.

As shown in Figure 6, the Ag nanowires have completely filled the AAO mold with a thickness of about 50 μm, that is, the slenderness ratio of the prepared Ag nanowires is as high as 250.

Example 5

1) Weigh 32 mg of Bi blocks and place them on an AAO mold with a pore size of about 200 nm;

2) The target temperature of the set plate is 533K, when the plate temperature reaches the set temperature, place the stacked Bi block/AAO mold between the two plates;

3) After the Bi block is heated, control the two flat plates to move relative to each other at a constant displacement loading rate of 3mm/min through the testing machine control software. When the load reaches 8KN, it is completely unloaded at a rate of 8KN/s;

4) Take out the sample, place it in KOH aqueous solution and completely corrode AAO at a temperature of 85 degrees Celsius, then soak and rinse with deionized water and absolute ethanol in turn;

5) The morphology of the nanowires on the surface of the sample was observed by SEM.

As shown in Figure 7, the Bi nanowires have completely filled the AAO mold with a thickness of about 50 μm, that is, the slenderness ratio of the prepared Bi nanowires is as high as 250.

Example 6

1) Weigh 60 mg of Pt block and place it on an AAO mold with a pore size of about 200 nm;

2) Set the target temperature of the flat plate to be 1093K, when the flat plate temperature reaches the set temperature, place the stacked Pt block/AAO mold between the two flat plates;

3) After the Pt block is heated, the two plates are controlled to move relative to each other at a constant displacement loading rate of 1.8mm/min through the testing machine control software. rate completely unloaded;

4) Take out the sample, place it in KOH aqueous solution and completely corrode AAO at a temperature of 85 degrees Celsius, then soak and rinse with deionized water and absolute ethanol in turn;

5) The morphology of the nanowires on the surface of the sample was observed by SEM.

As shown in Fig. 8, all Pt nanowires have regular and similar edges and faces, indicating that the prepared Pt nanowires are uniform single crystal nanowires.

Example 7

1) Weigh 50 mg of Pd block and place it on an AAO mold with a pore size of about 130 nm;

2) The target temperature of the set plate is 1093K, when the plate temperature reaches the set temperature, place the stacked Pd block/AAO mold between the two plates;

3) After the Pd block is heated, the two plates are controlled to move relative to each other at a constant displacement loading rate of 1.8mm/min through the testing machine control software. rate completely unloaded;

4) Take out the sample, place it in KOH aqueous solution and completely corrode AAO at a temperature of 85 degrees Celsius, then soak and rinse with deionized water and absolute ethanol in turn;

5) The morphology of the nanowires on the surface of the sample was observed by SEM.

As shown in Figure 9, the details of the prepared Pd nanowires such as edges and faces are not very clear in the SEM, which may be due to the serious oxidation of Pd at high temperature.

In addition to the above examples for the preparation of pure metal nanowire arrays, examples of nanowire preparation of metal alloys will also be shown below.

Example 8

1) Weigh 15 mg of Au ₈₀ Si ₂₀ (the subscripts refer to atomic percentages unless otherwise specified below) and place it on an AAO mold with a pore size of about 200 nm;

2) The target temperature of the set plate is 573K, when the plate temperature reaches the set temperature, place the stacked Au ₈₀ Si ₂₀ pieces/AAO molds between the two plates;

3) After the Au ₈₀ Si ₂₀ pieces are heated, the two plates are controlled by the testing machine control software to move relative to each other at a constant displacement loading rate of 0.6mm/min. When the load reaches 10KN, it is completely unloaded at a rate of 10KN/s;

4) Take out the sample, put it in KOH aqueous solution and completely corrode AAO at a temperature of 80 degrees Celsius, then soak and rinse with deionized water and absolute ethanol in turn;

5) The morphology of the nanowires on the surface of the sample was observed by SEM (Fig. 10).

Example 9

1) Weigh 10 mg of Au ₇₄ Co ₂₆ pieces and place them on an AAO mold with a pore diameter of about 200 nm;

2) The target temperature of the set plate is 1048K, when the plate temperature reaches the set temperature, place the stacked Au ₇₄ Co ₂₆ pieces/AAO molds between the two plates;

3) After the Au ₇₄ Co ₂₆ block is heated, the two flat plates are controlled by the testing machine control software to move relative to each other at a constant displacement loading rate of 1.8mm/min. The rate of s is completely unloaded;

4) Take out the sample, put it in KOH aqueous solution and completely corrode AAO at a temperature of 80 degrees Celsius, then soak and rinse with deionized water and absolute ethanol in turn;

5) The morphology of the nanowires on the surface of the sample was observed by SEM (Fig. 11).

Example 10

1) Weigh 25 mg of Ag ₃ In (here represents that the atomic ratio of Ag and In is 3:1) and place it on an AAO mold with a pore size of about 100 nm;

2) The target temperature of the set plate is 720K, when the plate temperature reaches the set temperature, place the stacked Ag ₃ In block/AAO mold between the two plates;

3) After the Ag ₃ In block is heated, the two plates are controlled by the testing machine control software to move relative to each other at a constant displacement loading rate of 1.8 mm/min. When the load reaches 10 KN, it is completely unloaded at a rate of 10 KN/s;

4) Take out the sample, put it in KOH aqueous solution and completely corrode AAO at a temperature of 80 degrees Celsius, then soak and rinse with deionized water and absolute ethanol in turn;

5) The morphology of the nanowires on the surface of the sample was observed by SEM (Fig. 12).

Example 11

1) Weigh 20mg Ag ₅₅ Al ₄₅ pieces and place them on an AAO mold with a hole diameter of about 100 nm;

2) The target temperature of the set plate is 720K, and after the plate temperature reaches the set temperature, the stacked Ag ₅₅ Al ₄₅ /AAO molds are placed between two plates;

3) After the Ag ₅₅ Al ₄₅ is heated, the two plates are controlled by the testing machine control software to move relative to each other at a constant displacement loading rate of 0.6mm/min. When the load reaches 10KN, it is completely unloaded at a rate of 10KN/s;

4) Take out the sample, put it in KOH aqueous solution and completely corrode AAO at a temperature of 80 degrees Celsius, then soak and rinse with deionized water and absolute ethanol in turn;

5) The morphology of the nanowires on the surface of the sample was observed by SEM (Fig. 13).

Example 12

1) Weigh 30 mg of Ag ₇₅ Ge ₂₅ pieces and place them on an AAO mold with a pore diameter of about 200 nm;

2) Set the target temperature of the plate to be 720K, when the plate temperature reaches the set temperature, place the stacked Ag ₇₅ Ge ₂₅ /AAO molds between the two plates;

3) After the Ag ₇₅ Ge ₂₅ is heated, the two plates are controlled by the testing machine control software to move relative to each other at a constant displacement loading rate of 1.8mm/min. When the load reaches 5KN, it is completely unloaded at a rate of 5KN/s;

4) Take out the sample, put it in KOH aqueous solution and completely corrode AAO at a temperature of 80 degrees Celsius, then soak and rinse with deionized water and absolute ethanol in turn;

5) The morphology of the nanowires on the surface of the sample was observed by SEM (Fig. 14).

Example 13

1) Weigh 15 mg of Cu _34.7 Zn _3.0 Sn _62.3 pieces and place them on an AAO mold with a hole diameter of about 100 nm;

2) The target temperature of the set plate is 768K, when the plate temperature reaches the set temperature, place the stacked Cu _34.7 Zn _3.0 Sn _62.3 pieces/AAO mold between the two plates;

3) After the Cu _34.7 Zn _3.0 Sn _62.3 is heated, the two plates are controlled by the testing machine control software to move relative to each other at a constant displacement loading rate of 1.8 mm/min. The rate of /s is completely unloaded;

4) Take out the sample, place it in KOH aqueous solution and completely corrode AAO at a temperature of 60 degrees Celsius, then soak and rinse with deionized water and absolute ethanol in sequence;

5) The morphology of the nanowires on the surface of the sample was observed by SEM (Fig. 15).

Example 14

1) Weigh 20mg of ordinary Cu wire block and place it on an AAO mold with a diameter of about 200nm;

2) Set the target temperature of the flat plate to 720K. When the flat plate temperature reaches the set temperature, place the stacked Cu wire block/AAO mold between the two flat plates;

3) After the Cu wire block is heated, control the two flat plates to move relative to each other at a constant displacement loading rate of 1.8mm/min through the testing machine control software. rate completely unloaded;

4) Take out the sample, place it in KOH aqueous solution and completely corrode AAO at a temperature of 40 degrees Celsius, then soak and rinse with deionized water and absolute ethanol in turn;

5) The morphology of the nanowires on the surface of the sample was observed by SEM (Fig. 16).

The above are only the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, without departing from the principles of the present invention, several improvements and modifications can be made. It should be regarded as the protection scope of the present invention.

Example 15

Using silicon mold and AAO mold to prepare Ag micro-nano secondary composite structure, the process steps are as follows:

1) A silicon wafer with a through hole diameter of 0.3 mm is stacked on the surface of an AAO mold with a diameter of 200 nm, and 0.11 g of Ag block is weighed and placed on top of the silicon mold;

2) The target temperature of the set plate is 943K, when the plate temperature reaches the set temperature, place the stacked Ag block/Si mold/AAO mold between the two plates;

3) After the Ag block is heated, the two plates are controlled by the testing machine control software to move relative to each other at a constant displacement loading rate of 0.1mm/min. rate completely unloaded;

4) Take out the sample, put it in KOH aqueous solution and completely corrode AAO at a temperature of 80 degrees Celsius, then soak and rinse with deionized water and absolute ethanol in turn;

5) The morphology of the micro-nano secondary structure on the surface of the sample was observed by SEM (Fig. 17). Example 16

Similarly, metal or metal alloy nano-hierarchical structures can be fabricated using composite AAO molds.

1) The Au block of about 40mg is weighed and placed on the upper surface of the composite AAO mold (the AAO mold body aperture is 200nm, but a thin layer of activation layer is attached on the upper surface, and the nanometer aperture in the activation layer is about 8nm);

2) Set the target temperature of the flat plate to be 773K, when the flat plate temperature reaches the set temperature, place the stacked Au block/AAO composite mold between the two flat plates;

3) After the Au block is heated, the two plates are controlled to move relative to each other at a constant displacement loading rate of 0.05mm/min through the testing machine control software. rate completely unloaded;

4) Take out the sample, put it in KOH aqueous solution and completely corrode AAO at a temperature of 80 degrees Celsius, then soak and rinse with deionized water and absolute ethanol in turn;

5) The morphology of the nano-multilevel structure on the surface of the sample was observed by SEM (Fig. 18).

In addition, this example also shows that the nanowire feature size that can be prepared by the method of the present invention can be as small as 8 nm.

In order to demonstrate the excellent performance of the prepared metal (or metal alloy) micro-nanostructures, in this example, the prepared Au nanowire arrays with different diameters are used as the substrate, and Crystal Violet (CV for short) molecules are used as the probes in this example. molecules, the significant enhancement effect of Au nanowire arrays on CV molecular Raman spectra was investigated (Figure 19). Wherein, the CV molecule used is an anhydrous ethanol solution with a concentration of 10 ^-5 mol/L. Compared to the bulk Au surface without the surface micro-nanostructure, the Au surface with the nanowire array resulted in a significant enhancement of all the characteristic Raman peaks of the CV molecules (Fig. 19). This example fully demonstrates the potential application of metal or metal alloy nanostructures represented by Au in high-sensitivity molecular detection.

The above examples illustrate schematically that the methods and principles of the present invention can be generally used to fabricate metal or metal alloy micro-nanowire arrays with various physicochemical properties and functional applications, including surface plasmonic optical properties Nanostructures represented by metals such as Au, Ag, Cu, nanostructures represented by Pt, Pd, Cu, etc. with photocatalytic and chemical catalytic properties, and nanostructures represented by Au ₇₄ Co ₂₆ with magnetic properties, Nanostructures represented by Cu _34.7 Zn _3.0 Sn _62.3 with shape memory properties.

Claims (5)

1. a method for preparing metal micro-nano structure, is characterized in that, comprises the following steps: (1) heating the metal and the mold with the micro-nano structure to a temperature T, wherein 0.5T _m <T < T _m , T represents the absolute temperature, and T _m represents the melting point temperature of the metal according to the absolute temperature scale; (2) applying a load to press the metal with a temperature of T into the mold to obtain a composite structure formed by the mold and the metal; (3) removing the mold to obtain a metal with a micro-nano structure feature size of 8nm-200nm; The metal is any of Bi, Cu, Au, Ag, Pt, Pd, Au ₈₀ Si ₂₀ , Au ₇₄ Co ₂₆ , Ag ₃ In, Ag ₅₅ Al ₄₅ , Ag ₇₅ Ge ₂₅ , Cu _34.7 Zn _3.0 Sn _62.3 A sort of; When the metal is Au, T≥773K; When the metal is Ag, T≥943K; When the metal is Bi, T≥533K; When the metal is Pt, T≥1093K; When the metal is Pd, T≥1093K; When the metal is Au ₈₀ Si ₂₀ , T≥573K; When the metal is Au ₇₄ Co ₂₆ , T≥1048K; When the metal is Ag ₃ In, T≥720K; When the metal is Ag ₅₅ Al ₄₅ , T≥720K; When the metal is Ag ₇₅ Ge ₂₅ , T≥720K; When the metal is Cu _34.7 Zn _3.0 Sn _62.3 , T≥768K; When the metal is Cu, T≥720K. 2 . The method of claim 1 , wherein the mold material with the micro-nano structure is silicon, silicon oxide, aluminum oxide or other inorganic oxides. 3 . 3 . The method for preparing a metal micro-nano structure according to claim 2 , wherein the removal method in step (3) is chemical corrosion. 4 . 4. the method for preparing metal micro-nano structure as claimed in claim 3 is characterized in that: described step (3) specifically comprises the following steps: the composite structure formed by mould and metal is placed in lye or acid solution, Heating, until the mold is completely corroded, and then soaking and rinsing with deionized water, acetone or absolute ethanol in sequence to obtain a metal with a micro-nano structure. 5. The method for preparing a metal micro-nano structure according to claim 1, wherein the metal is in the form of a block, a sheet or a particle.