RU2555366C2 - Method of obtaining anode aluminium oxide with highly ordered porous structure and method of forming arrays of anisotropic nanostructures on its base - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to method of obtaining porous film with highly ordered system of pores, forming strict hexagonal grid, as well as to method of forming highly ordered arrays of anisotropic structures. Monocrystalline aluminium with crystallographic orientation A1 (111), A1(110) are used as initial material to realise method of obtaining porous film with highly ordered system of pores, forming strict hexagonal grid, by anode aluminium oxidation. Method of forming highly ordered arrays of anisotropic nanostructures is realised by electrochemical precipitation of introduced substance from respective solutions of electrolytes in channels of porous matrix. Porous film, obtained by said method, is used as matrix.

EFFECT: increased regularity and homogeneity of porous structure of anode aluminium oxide films, possibility to obtain highly ordered arrays of anisotropic nanostructures based on said films and to extend area of practical application of porous anode aluminium oxide films and based on it arrays of nanostructures.

19 cl, 1 tbl, 11 dwg, 4 ex

Description

The invention relates to the field of nanotechnology, and in particular to a method for producing anodic alumina films with a highly ordered pore system forming a strict hexagonal lattice over an area of more than 1 cm ² and arrays of anisotropic nanostructures based on them and can be used to obtain nanostructures with various functional properties ( magnetic, optical, catalytic, etc.) and the creation on their basis of calibration gratings for atomic force microscopes, magnetic information storage devices and high resolution of electromagnetic radiation detectors.

The technology of anodic oxidation of metals and the use of oxide films as protective and decorative coatings has a long history. The first patent on the use of anode coatings to protect aluminum and its alloys from corrosion appeared in 1923 [British Patent 223994, 1923]. In 1995, anodic alumina again attracted the attention of researchers, due to the discovery of the possibility of producing films with a self-ordered porous structure over a large area after prolonged anodic oxidation [Masuda Η., K. Fukuda, Science (1995), v. 268, pp. 1466-14682]. This discovery made a breakthrough in the technology of producing porous structures with a very narrow pore size distribution and high values of geometric anisotropy (more than 1000).

The ideal structure of anodic alumina films can be represented as a system of ordered pores with dense hexagonal packing. In this case, the pores are located perpendicular to the surface of the substrate, and their diameter D _p , as well as the distance between adjacent pores D _int , can be varied over a wide range (D _p = 3-250 nm; D _int = 5-500 nm).

Studies of the process of anodic oxidation of aluminum have shown that an ordered pore structure is formed only under certain conditions. For example, oxide films with an ordered porous structure with a distance between adjacent pores of 65, 105 and 500 nm are formed at a voltage of 25 V in sulfuric acid, at 40 V in oxalic acid, and 195 V in phosphoric [Nielsch K., Choi J., Schifrin K., Wehrspohn R. B., Gosele U., Nano Letters (2002), v. 2, pp. 677-680]. It should be emphasized that the degree of ordering of the porous structure of the anode films is critical for their practical application. Two-dimensional photonic crystals, storage devices with ultra-high recording density, submicron analogues of lithographic gratings for calibrating scanning probe microscopes, position-sensitive detectors with record resolution are all devices that can only be obtained using porous oxide films with a highly ordered structure.

Currently, porous alumina films are most widely used as matrices for the synthesis of ordered arrays of anisotropic nanostructures of various compositions.

The creation of practically defect-free single-domain structures is possible using the "nanoimprint" technology, which consists in preliminary applying small depressions on a flat aluminum surface, in which pores are formed during subsequent metal oxidation [Choi J., K. Nielsch, Reiche Μ., Wehrspohn RB, Gosele U., J. Vac. Sci. Technol. In (2003), v. 21, pp. 763-766]. To obtain such recesses, a special stamp with periodic protrusions made using x-ray or electronic lithography is used. Despite the fact that lithographic technologies are characterized by low productivity and high cost, the possibility of repeated use of the stamp makes this method as a whole quite technological and economical.

It should be remembered that the distance between adjacent pores depends on the voltage (D _int = kU, where 2.0≤k (nm / V) ≤ 2.8). Anodic oxidation of aluminum with printed recesses on the surface is carried out, respectively, at a voltage of U = D _int / k.

The disadvantages of the nanoimprint technology are:

1) the impossibility of creating ordered structures with a short period (less than 200 nm), which is primarily associated with the problems of manufacturing a suitable stamp even with the use of modern lithographic technologies;

2) violation of the ordering of pores as the length of the formed channels increases.

Note that the shape and orientation of the pores in the oxide film completely determine the size and relative position of the nanostructures formed on their basis. For the synthesis of one-dimensional nanostructures, matrices based on mesoporous silica [US 7001669], block copolymer films [US 7190049], porous films of anodic alumina [US 6231744] are used. The disadvantage of the proposed methods is the use of porous matrices with an insufficiently ordered structure, which excludes the possibility of obtaining highly ordered arrays of anisotropic nanostructures.

Several methods are known for producing porous anodic alumina films with an ordered structure, for example, the two-stage anodic oxidation method [Shingubara S., Journal of Nanoparticle Research (2003), v. 5, pp. 17-30].

Closest to the claimed method for producing an anodic alumina film (prototype) is the method of "hard" anodic oxidation - a method for producing anodic alumina film with a highly ordered pore system forming a strict hexagonal lattice, according to the international application WO 2008/014977 [Lee W., Ji R., Gosele U., Nielsch K., Nature Materials (2006), v. 5, pp. 741-747], including anodic oxidation of aluminum at high current densities.

Also, from the international application WO 2008/014977, a method is known for forming a highly ordered array of nanostructures by electrochemical deposition of an introduced substance - a metal or a semiconductor compound from an appropriate electrolyte solution in the pores of a porous matrix - anodic alumina film.

Using this method, it is possible to obtain porous films of anodic alumina with an ordered arrangement of channels with a structure period from 65 to 500 nm. The disadvantage of this method is the formation of a multidomain porous structure with a small size (usually less than 10 microns in the lateral direction) of ordered regions. Hereinafter, by “domain” is meant the region of the oxide film within which the pores form a strict hexagonal packing. In addition, the domains in the oxide films obtained by self-organization are completely misoriented relative to each other. The mutual orientation of the ordered regions is judged by the diffraction patterns recorded during normal incidence of the probe radiation on the film plane, or by Fourier images from microphotographs obtained from a large region of the sample [Napolskii KS, Roslyakov IV, Eliseev A.A., Petukhov AV, Byelov DV, Grigoryeva NA, Bouwman WG, Lukashin AV, Kvashnina KO, Chumakov AP, Grigoriev SV, Journal of Applied Crystallography, (2010), v. 43, pp. 531-538.]. Note that in small-angle diffraction patterns (or Fourier images of microphotographs), concentric rings with a uniform intensity distribution are observed for samples with a system of misoriented domains, while for porous films with a highly ordered structure, a set of diffraction peaks with hexagonal symmetry is observed.

In connection with the foregoing, the development of methods for producing films of anodic alumina with a highly ordered porous structure (single-domain or multi-domain with low mosaicity) with a frequency of less than 200 nm, as well as the development of methods for the formation of anisotropic nanostructures based on them is an important task of modern science and technology.

The objective of the invention is to develop a method for producing films based on anodic alumina with a highly ordered pore system forming a strict hexagonal lattice over an area of more than 1 cm, obtained without using lithography techniques, as well as a method for forming highly ordered arrays of anisotropic nanostructures for various functional purposes.

The technical result of the invention lies in the possibility of obtaining films of anodic alumina with a highly ordered structure (standard deviation of the average orientation of the pore system at various points of the porous film is less than 3 °) over a large area (at least 1 cm), with a small dispersion of the distance between the pores (less than 5% ) and a small dispersion of pores in size (less than 15%), as well as the possibility of obtaining highly ordered arrays of anisotropic nanostructures based on these films with the corresponding organization of nanostructures in porous matrix, and expanding the range of practical applications of porous films of anodic alumina and arrays of nanostructures based on them (for example, as two-dimensional photonic crystals, storage devices with ultra-high recording density, submicron analogs of lithographic gratings for calibrating scanning probe microscopes, position-sensitive detectors with record resolution).

To achieve this result, in the method for producing an anodic alumina film with a highly ordered system of pores forming a strict hexagonal lattice, high-purity (more than 99.99%) single-crystal aluminum with (111) orientation is used. To improve the ordering of the structure, aluminum substrates with a smooth or periodically rough surface are anodized.

Anodic oxidation of aluminum is carried out in an aqueous or aqueous-alcoholic acid solution.

The formed oxide films are characterized by a standard deviation of the average orientation of the pore system at various points of the porous film, not exceeding 3 °.

The film thickness of the anodic alumina is from 500 nm to 300 μm.

The diameter of the channels in the film of anodic alumina is from 5 nm to 300 nm.

The dispersion of pores in size is less than 15%.

The period of the porous structure of the film of anodic alumina is from 10 nm to 500 nm.

The dispersion of the distances between adjacent pores is less than 5%.

The specified technical result is also achieved by the fact that for a controlled increase in pore diameter, additional chemical etching of the film of anodic aluminum oxide in a dilute acid solution is carried out at a temperature of 20 ÷ 90 ° C.

The indicated technical result for the method of forming highly ordered arrays of anisotropic nanostructures is achieved by the fact that a porous film of anodic alumina with a highly ordered pore system obtained by the above method is used as a matrix, and the formation of highly ordered arrays of anisotropic nanostructures is carried out by the method of electrochemical deposition of the introduced substance from the corresponding electrolyte solutions.

The degree of filling of the pores with the introduced substance exceeds 80%. The geometric anisotropy factor of nanostructures is up to 100,000.

The diameter of anisotropic nanostructures is from 5 nm to 300 nm. The dispersion of anisotropic nanostructures in size is less than 15%.

The distance between adjacent nanostructures in their array is from 10 nm to 500 nm.

The dispersion of the distances between adjacent nanostructures is less than 5%.

The standard deviation of the average orientation of the system of nanostructures at various points in the array does not exceed 3 °.

The invention is illustrated by the following drawings.

FIG. 1. Scheme for the production of anodic alumina films with a highly ordered pore system forming a strict hexagonal lattice over an area of more than 1 cm ² and arrays of anisotropic nanostructures based on them.

FIG. 2. Small-angle X-ray diffraction data for an alumina film with a highly ordered porous structure obtained on Α1 (111) in 0.3 Μ oxalic acid at 40 V.

FIG. 3. Micrograph of the lower surface of the porous alumina film obtained by anodic oxidation of high-purity aluminum with an orientation of (111) of 0.3 Μ (COOH) ₂ at 40 V (A). Schematic representation of the mutual orientation of the pore system in the oxide film and the crystal structure of the metal substrate with the (111) (B) orientation.

FIG. 4. Micrograph of the lower surface of the porous alumina film obtained by anodic oxidation of high-purity single-crystal aluminum with a smooth surface (A) and a periodically rough surface (B) of 0.3 Μ (COOH) ₂ at 40 V for 24 hours. The period of roughness on the surface of the starting aluminum coincides with the period of the porous structure and is equal to 105 nm.

FIG. 5. Micrograph of the transverse cleavage of the Co_Al ₂ O ₃ nanocomposite containing filamentous cobalt nanostructures in the porous matrix of anodic alumina. An oxide film was obtained by anodic oxidation of an aluminum single crystal in 0.3 Μ an aqueous solution of oxalic acid at 40 V (A). Micrograph of filamentous Co nanostructures after dissolution of matrix (B).

FIG. 6. Scanning electron microscopy data for the transverse cleavage of the Ni _1-x Cu _x / Cu_Al ₂ O ₃ nanocomposite containing layered whisker nanostructures in the porous matrix of anodic alumina. An oxide film was obtained by anodic oxidation of an aluminum single crystal with a (111) orientation in a 0.3 Μ aqueous solution of oxalic acid at 40 V. Microphotographs of layered filamentous Ni _1-x Cu _x / Cu nanostructures after dissolution of the matrix (B, C).

The proposed method is as follows.

Films of aluminum oxide with a highly ordered porous structure, which subsequently act as matrices for obtaining an array of anisotropic nanostructures of various functional purposes, are obtained by the method of anodic oxidation of aluminum (Fig. 1). As a billet (source material), plates with a thickness of at least 0.1 mm high-purity (A1 content of at least 99.99%) single-crystal (misorientation of blocks no more than 3 °) aluminum are used. A single crystal of aluminum with a known crystallographic orientation is used (optimal (111), (110) and faces of lower symmetry are also suitable, A1 (100) is undesirable). It is also possible to use polycrystals with a large grain size of the metal. In this case, the proposed approach is valid when using an oxide film formed on a single grain. Before anodic oxidation, the metal surface is subjected to mechanical and / or electrochemical polishing (roughness class not lower than 12).

As anodic oxidation electrolytes are used aqueous solutions of acids that slightly dissolve alumina (for example, solutions of oxalic Н ₂ С ₂ О ₄ , phosphoric Н ₃ РО ₄ , sulfuric Н ₂ SO ₄ , succinic C ₄ H ₆ O ₄ , citric С _b H ₈ O ₇ acids). The electrolyte concentration varies from 0.05 to 0.5 mol / liter. It is possible to use additives leading to lowering the freezing temperature of the electrolyte, such as ethanol, ethylene glycol, etc. Anodic oxidation is carried out at a temperature of -20 ÷ 10 ° C and a voltage in the range from 5 to 250 V. The thickness of the obtained aluminum oxide film can vary from 0 , 1 to 200 microns, depending on the mode of anodic oxidation and its duration. The pore diameter (from 5 to 300 nm) and the distance between adjacent channels (from 20 to 600 nm) in the oxide film depends on the anodic oxidation mode.

In the case of using aluminum with a smooth surface to form an oxide film with a highly ordered structure, anodic oxidation is carried out in two stages. After the first cycle of anodic oxidation (Fig. 1, stage 2), the oxide film formed on the surface A1 is selectively dissolved (Fig. 1, stage 3). Then spend the second cycle of anodic oxidation in the same conditions (Fig. 1, stage 4). The duration of the second anodic oxidation is selected taking into account the required thickness of the oxide film.

In the case of using substrates with a periodically rough surface, which is created by anodizing and removing the oxide film or by mechanical action on the smooth surface of aluminum, stages 1-3 (Fig. 1) are excluded from the process.

The result is a porous alumina film in which all domains over a large area are oriented along the selected direction (Fig. 2) defined by the crystallographic orientation of the substrate (Fig. 3).

To separate the oxide film from the aluminum substrate, selective dissolution of the unreacted metal is carried out (Fig. 1, stage 5). To obtain a material with through pores, chemical etching of oxide films in dilute acid solutions is carried out at a temperature of 20 ÷ 90 ° C (Fig. 1, stage 6). If necessary, the pore diameter can be increased by chemical etching of the oxide film in the used electrolyte solution or dilute acid solutions at a temperature of 20 ÷ 90 ° C for 5 ÷ 600 minutes (Fig. 1, stage 7). Then the film is washed and dried in air.

The resulting thin ceramic porous film can be subjected to high-temperature annealing (up to 1200 ° C) to increase the mechanical strength and chemical stability in acidic and alkaline solutions of electrolytes, which are subsequently used to deposit nanostructures in the channels of the porous matrix.

To form a porous electrode, a layer of metal (Au, Pt, etc.) is sprayed (thermally, magnetron, etc.) onto one of the sides of the resulting template (porous matrix), see FIG. 1, stage 8.

The synthesis of nanostructures based on metals, their alloys, as well as semiconductors is carried out by electrodeposition of the required compounds in the channels of the porous matrix (Fig. 1, stage 9). Potentiostatic electrocrystallization modes are preferred. The diameter of the formed nanostructures coincides with the pore diameter of the initial matrix, and their length is determined by the charge missed during the electrocrystallization process and by the geometric characteristics of the template.

The following examples illustrate the invention, but in no way limit its scope.

Example 1

Films of anodic alumina with a highly ordered porous structure with a period of 105 nm are obtained as follows.

An aluminum single crystal with a known crystallographic orientation (optimal (111), A1 (110) is also suitable and faces of lower symmetry, but the porous films formed have a higher mosaic structure than A1 (111), A1 (100) is undesirable) subjected to mechanical or electrochemical polishing to a mirror finish. Then the smooth surface of the metal is thoroughly washed with acetone and distilled water; the sample is fixed in a two-electrode electrochemical cell. Anodic oxidation of aluminum is carried out at a temperature of 0 ° C in an aqueous solution of oxalic acid 0.3 Μ (COOH) ₂ at a constant voltage of 40 V. An anode is an aluminum plate, and a platinum wire or plate serves as an auxiliary electrode. After the first cycle of anodic oxidation, the duration of which is more than 24 hours, the oxide film formed on the surface A1 is selectively dissolved in an aqueous solution containing 0.2 Μ CrO ₃ and 0.6 Μ H ₃ PO ₄ at a temperature of 70 ° C for 1 hour . Then spend the second cycle of anodic oxidation in the same conditions. The duration of the second anodic oxidation is selected taking into account the required thickness of the oxide film (the growth rate of the oxide layer under the selected conditions is about 2 μm / h). To separate the oxide film from the aluminum substrate, the latter is selectively dissolved in 10 vol. % solution of Br ₂ in CH ₃ OH or in an aqueous solution containing 0.5 Μ CuCl ₂ and 5% Hcl. Then the film is washed with distilled water and dried in air.

The result is a film of anodic alumina with a highly ordered porous structure with a period of 105 nm, in which the orientation of the pore system is determined by the crystallographic orientation of the substrate. According to scanning electron microscopy (Fig. 3), in the case of the (111) face, the rows of pores are oriented along the <110> directions. It is important to note, since the rows of pores are oriented along the directions <110> in the plane of the substrate, which is a single crystal, the orientation of the rows of pores is the same at different points of the sample, arbitrarily far removed from each other. On the contrary, during the oxidation of commonly used polycrystalline substrates, the orientation of the pore system at different points of the porous film is different, which does not allow the use of such films in a number of applications, including the creation of calibration gratings for atomic force microscopes and magnetic devices for storing information with an ultrahigh recording density high-resolution electromagnetic radiation detectors, etc.

Example 2

The ordering of the porous structure of the films of anodic alumina is improved as follows.

An aluminum single crystal with a known crystallographic orientation (optimal (111), A1 (110) is also suitable and faces of lower symmetry, but the porous films formed have a higher mosaic structure than A1 (111), A1 (100) is undesirable) subjected to mechanical or electrochemical polishing to a mirror finish. Then, a periodically rough relief is formed on a smooth metal surface with a periodicity that coincides with the period created in the future by the porous structure of anodic alumina. This relief can be obtained in several ways, for example, by anodic oxidation of aluminum and selective removal of the oxide film or by mechanical deposition of microroughnesses using a stamp with protrusions periodically located on its surface.

Anodic oxidation of aluminum is carried out at a temperature of 0 ° C in an aqueous solution of oxalic acid 0.3 M (COOH) ₂ at 40 V for 24 hours. An anode is an aluminum plate, and an auxiliary electrode is a platinum wire or plate. To separate the oxide film from the aluminum substrate, the latter is selectively dissolved in 10 vol. % solution of Br ₂ in CH ₃ OH or in an aqueous solution containing 0.5 Μ CuCl ₂ and 5% Hcl. Then the film is washed with distilled water and dried in air.

The result is a film of anodic alumina with a highly ordered porous structure with a period of 105 nm, in which the orientation of the pore system is determined by the crystallographic orientation of the substrate. Moreover, the domain size is larger when anodizing aluminum with a periodically rough surface (see Fig. 4A) compared with an oxide film obtained on a polished smooth metal surface (see Fig. 4B).

Example 3

Highly ordered arrays of anisotropic magnetic nanostructures based on metals (Ni, Co) and alloys (Νi _1-x Cu _x ) are obtained as follows.

The synthesis of a porous matrix that determines the diameter and relative orientation of metal nanowires is carried out according to the method described in detail in examples 1 and 2. To obtain a template with through pores, etching of oxide films of 5 masses is carried out. % solution of H ₃ PO ₄ at 60 ° C for 5 minutes A layer of gold 100-200 nm thick is thermally sprayed on one side of the resulting template. Thermal spraying of gold is carried out using a vacuum post (vacuum is not higher than 10 ^-5 mm Hg, the temperature of the evaporator is about 2000 ° C). A portion of 80-100 mg of Au is placed on a W plate serving as a heater. Porous films are placed above the evaporator at a distance of 100-200 mm. After pumping the chamber to a residual pressure of 10 ^-5 mm RT. Through a tungsten plate, a current of ~ 5 A is passed, which leads to its heating. After evaporation of the entire sample of gold, the supply of electric current is stopped. Then air is blown into the chamber until atmospheric pressure is reached and the porous films are removed.

The synthesis of magnetic nanostructures based on metals and alloys is carried out by electrocrystallization in a potentiostatic mode. An electrode based on porous anode films is placed in an electrolyte solution of the required composition, the vessel is connected to a water-jet pump. The sample is kept in an electrolyte solution under reduced pressure for 30 minutes, and then fixed in a three-electrode electrochemical cell. A platinum wire is used as an auxiliary electrode, and a saturated silver chloride electrode is used as a reference electrode. The working electrode is a porous film with a sprayed layer of gold.

The template is fixed horizontally, the tip of the Luggin capillary connecting the working space of the electrochemical cell with the capacitance for the reference electrode is brought to the surface of the porous matrix no further than 1-2 mm.

The electrodeposition of a metal or alloy is carried out in a potentiostatic mode. The composition of the electrolyte and the deposition potential are selected depending on the required chemical composition of the resulting nanostructures (table 1).

According to scanning electron microscopy (Fig. 5A, B), the indicated conditions of electrocrystallization lead to the formation of extended (more than 30 microns in length, 50 nm in diameter) metal nanostructures. The resulting material exhibits anisotropy of magnetic properties. The axis of easy magnetization is directed along the long axis of the nanowires.

Example 4

Highly ordered arrays of layered Ni _1-x Cu _x / Cu nanowires are prepared as follows.

The synthesis of a porous matrix that determines the diameter and relative orientation of metal nanowires is carried out according to the method described in detail in examples 1 and 2. To obtain a template with through pores, etching of oxide films of 5 masses is carried out. % solution of H ₃ PO ₄ at 60 ° C for 5 minutes A layer of gold 100-200 nm thick is thermally sprayed on one side of the resulting template. Thermal spraying of gold is carried out using a vacuum post (vacuum is not higher than 10 ^-5 mm Hg, the temperature of the evaporator is about 2000 ° C). A sample of Au weighing 80-100 mg is placed on a W plate serving as a heater. Porous films are placed above the evaporator at a distance of 100-200 mm. After pumping the chamber to a residual pressure of 10 ^-5 mm RT. Art. A current of about 5 A is passed through the tungsten plate, which leads to its heating. After evaporation of the entire sample of gold, the supply of electric current is stopped. Then air is blown into the chamber until atmospheric pressure is reached and the porous films are removed.

The synthesis of magnetic nanostructures with a variable composition (layered nanowires) is carried out by alternating electrocrystallization of metals in a potentiostatic mode from a joint electrolyte. An electrode based on porous anode films is placed in an electrolyte solution of the required composition, the vessel is connected to a water-jet pump. The sample is kept in an electrolyte solution under reduced pressure for 30 minutes, and then fixed in a three-electrode electrochemical cell. A platinum wire is used as an auxiliary electrode, and a saturated silver chloride electrode is used as a reference electrode. The working electrode is a porous film with a sprayed layer of gold.

The template is fixed horizontally, the tip of the Luggin capillary connecting the working space of the electrochemical cell with the capacitance for the reference electrode is brought to the surface of the porous matrix no further than 1-2 mm.

The electrodeposition of layered nanowires is carried out by alternating deposition of metals from an electrolyte of the following composition 0.005 Μ CuSO ₄ +0.5 Μ NiSO ₄ +0.6 Μ H ₃ VO ₃ . The deposition potential of copper segments E _d (Cu) = - 0.4 V, the nickel deposition potential Ed (Ni) = - 1.0 V.

According to scanning electron microscopy (Fig. 6A-B), these electrocrystallization conditions lead to the formation of extended (over 40 microns in length, 50 nm in diameter) metal layered nanostructures. The resulting material exhibits anisotropy of magnetic properties. The direction of the axis of easy magnetization depends on the geometric anisotropy of the magnetic segments.

Thus, the proposed technical solution allows the manufacture of films of anodic alumina with a highly ordered porous structure and arrays of anisotropic nanostructures based on them. Geometrical characteristics of nanostructures: pore diameter 5-300 nm, porous structure periodicity 10-500 nm, oxide film thickness 0.5-300 μm, standard deviation of the average orientation of the pore system at various points of the porous film on a scale of more than 1 cm less than 3 °, diameter anisotropic nanostructures of 5-300 nm, a length of 0.5-300 microns, the degree of filling of the channels with the introduced substance is not less than 80%, the standard deviation of the average orientation of the system of nanostructures at various points of the array at a scale of more than 1 cm less than 3 °.

Claims (19)

1. A method of producing a porous film with a highly ordered system of pores forming a strict hexagonal lattice by anodic oxidation of aluminum, characterized in that single-crystal aluminum with a crystallographic orientation of A1 (111), A1 (110) is used as the starting material. 2. The method according to p. 1, characterized in that A1 is used as a substrate with a smooth or periodically rough surface. 3. The method according to p. 1, characterized in that as single-crystal aluminum using high-purity aluminum (more than 99.99%). 4. The method according to p. 1, characterized in that the anodic oxidation of aluminum is carried out in an aqueous or aqueous-alcoholic acid solution. 5. The method according to p. 1, characterized in that the standard deviation of the average orientation of the pore system at various points of the porous film does not exceed 3 °. 6. The method according to p. 1, characterized in that the film thickness of the anodic alumina is from 500 nm to 300 microns. 7. The method according to p. 1, characterized in that the diameter of the channels in the film of anodic alumina is from 5 nm to 300 nm. 8. The method according to p. 1, characterized in that the dispersion of pores in size is less than 15%. 9. The method according to p. 1, characterized in that the period of the porous structure of the film of anodic alumina is from 10 nm to 500 nm. 10. The method according to p. 1, characterized in that the dispersion of the distances between adjacent pores is less than 5%. 11. The method according to p. 1, characterized in that it further conducts chemical etching of the film of anodic alumina in a dilute acid solution at a temperature of 20 ÷ 90 ° C. 12. The method of forming highly ordered arrays of anisotropic nanostructures by electrochemical deposition of the introduced substance from the corresponding solutions of electrolytes in the channels of the porous matrix, characterized in that a porous film obtained by the method according to claim 1 is used as a porous matrix. 13. The method according to p. 12, characterized in that the degree of filling of the pores with the introduced substance exceeds 80%. 14. The method according to p. 12, characterized in that the geometric anisotropy factor of the nanostructures is up to 100,000. 15. The method according to p. 12, characterized in that the diameter of the anisotropic nanostructures is from 5 nm to 300 nm. 16. The method according to p. 12, characterized in that the dispersion of anisotropic nanostructures in size is less than 15%. 17. The method according to p. 12, characterized in that the distance between adjacent nanostructures in their array is from 10 nm to 500 nm. 18. The method according to p. 12, characterized in that the dispersion of the distances between adjacent nanostructures is less than 5%. 19. The method according to p. 12, characterized in that the standard deviation of the average orientation of the system of nanostructures at various points in the array does not exceed 3 °.

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