RU2412108C2 - Method to produce nanoparticles and device for its realisation - Google Patents

Abstract

FIELD: nanotechnologies.

SUBSTANCE: invention relates to methods and devices to produce particles of nanometre size, to create sensor, electronic and optoelectronic instruments and highly selective solid-state catalysts. Melted material is dispersed. Produced liquid microdrops of this material are sent into flow of electrons to recharge microdrops to condition, when their cascade division starts to produce nanoparticles applied onto substrate. At the same time parametres of electrons flow and time of liquid drops stay in it comply with certain ratios. Proposed device comprises the following components arranged in vacuum chamber and installed coaxially - unit of microdrops flow formation with cathode and anide, unit of microdrops recharging and unit of nanoparticles deposition with disk cathode with central hole, anode and substrate installed on anode. At the same time unit of microdrops flow formation is installed with axial gap relative to unit of microdops recharging, around which a circular control electrode is installed, connected to controlled source of voltage. Additionally unit of microdrops flow formation comprises dielectric disk with central hole, in circular slot of which there is a circular cathode installed, and anode is arranged in the form of metal needle, being the first anode. And unit of microdrops recharging comprises dielectric vessel in the form of round hollow cylinder with central end holes, where the first round cylindrical cathode and the first round cylindrical metal net, being the second anode, are installed, between which the first emitter of electrons is installed.

EFFECT: invention provides for formation of nanostructure from nanoparticles of smaller size and with narrower dispersion.

15 cl, 3 dwg

Description

The invention relates to methods and devices for producing nanometer-sized particles that are used in various fields of science and technology, in particular, metal nanostructures are considered as a promising material for creating new sensor, electronic and optoelectronic devices, as well as in the development of new types of highly selective solid-state catalysts .

Nanostructures with a surface density of particles of the order of 10 ¹² cm ^-2 are promising for the creation of efficient nanoelectronic devices, such as ultrafast switches or ultracompact memory cells (K.-H.Yoo, JWPark, J.Kirn, KSPark, JJLee and JBChoi. Appt. Phys. Lett., 1999, v. 74 (14), p. 2073).

So, when forming close-packed nanostructures with a granule size of ~ 4 nm, it is possible to create memory devices with an information recording density of ~ 10 ¹¹ bit / cm ² (F. Picus and Likharev. Appl. Phys. Lett., 1997, v. 71, p. 3666 ; Y. Naveh and Likharev. Superlattices and Microstructures 2000, v. 27, p. 1). In the extreme case, reducing the size of the granules to ~ 1 nm leads to an increase in the recording density of information to 10 ¹² bit / cm ² .

A new direction in catalytic chemistry is also developing intensively - heterogeneous catalysis on nanostructured materials (P.S. Vorontsov, E.I. Grigoriev, S.A. Zavyalov, L.M. Zavyalova, T.N. Rostovschikova, O.V. Zagorskaya Chem. Physics, 2002, v.21, p. 1). Most of the catalysts studied in laboratories and used in technology contain nanoparticles, i.e. particles whose size lies in the range of 1-100 nm. The fundamental difference between nanoparticles and bulk materials is that in them the fraction of surface atoms is comparable with the number of atoms in the volume, and the radius of curvature of the surface is comparable to the lattice constant. It is generally accepted that precisely these features provide a high catalytic activity of nanostructured catalysts in comparison with their analogues based on bulk materials. For a number of important practical applications, the most promising are catalysts based on metal nanostructures containing nanoparticles of Cu, Pt, Pd, Ni, Fe, Co, and other metals.

Known methods and devices for producing nanoparticles of various materials can be divided into two large groups: in the first, nanoparticles are formed as a result of combining atoms (or more complex radicals and molecules), in the second - as a result of dispersion of bulk materials.

Numerous methods and devices are known based on combining atoms (radicals, molecules) into nanoparticles, including, for example, thermal evaporation and condensation (see S. Tohno, M. ltoh, S. Aono, H. Takano, J. Colloid Interface Sci . - 1996, v.180, p.574), ion sputtering (see US patent No. 5879827, IPC H01M 04/36, published 09.03.1999), recovery from solutions (see US patent No. 6090858; IPC C09K 03 / 00, published July 18, 2000), recovery in microemulsions (see H. Herrig, R. Hempelmann, Mater. Lett. - 1996, v. 27, p. 287).

A known method of producing nanoparticles of platinum metals with iron, in particular Fe-Pt, Fe-Pd nanoparticles (see application RU No. 2007106183, IPC B22F 9/14, published on 08.27.2008), in which an alloy is used to obtain particles of a certain composition and size iron and platinum metals. The alloy is electrochemically dissolved at an anode potential lower than the dissolution potential of platinum metal microareas in the crystal lattice of the alloy and nanoparticles are obtained in the form of an undissolved precipitate — anode sludge.

It should be noted that the resulting nanoparticles have a crystalline structure and also coagulate upon contact, which limits the applicability of the fabricated structures.

A device for producing microparticles is known (see US patent No. 7252814, IPC СВВ 17/20, published 07.08.2007) containing a reaction chamber with an inlet pipe for supplying a reagent and an outlet pipe for outputting the resulting crystalline nanoparticles. A heater is placed in the chamber to create a temperature gradient along the reaction chamber, as well as an optical radiation source that creates a radiation intensity gradient along the reaction chamber.

Nanoparticles obtained using a known device have a crystalline structure and also coagulate upon contact.

A known method of producing microfibers from diamond nanoparticles (see patent RU No. 2244680, IPC C01B 31/06, B82B 3/00, published January 20, 2005), in which a sample of ultrafine diamonds with an average particle size of 4 nm is loaded into a mold, pressed into a pill. A compressed tablet is used as a target, which is placed in a vacuum chamber. After evacuation of the chamber, buffer gas is introduced. The target is cooled to -100 ° C and maintained until the mass increases by 2.0-4.0 times from the initial mass. A constant voltage is applied to the electrodes of the vacuum chamber. The target is irradiated with pulsed laser radiation with a power that causes the heating of the nanodiamond particles to no more than 900 ° C. The sprayed target material forms microfibers between the electrodes. To reduce the brittleness of microfibers, non-ionic type polymer vapors, such as polyvinyl alcohol, polyvinyl butyral, polyacrylamide, are fed into the chamber immediately after exposure to laser radiation to a pressure of 10 ^-2 -10 ^-4 atm. The resulting microfibers have a diamond structure, are stable after storage for a month, and the fraction of the non-diamond phase does not exceed 6.22%.

However, this method is not intended for the formation of metal nanoparticles, which significantly limits the possibilities of its application.

A device for producing microfibers from diamond nanoparticles is known (see patent RU No. 2244680, IPC СВВ 31/06, В82В 3/00, published January 20, 2005), containing a pulsed He-Ne laser, a vacuum chamber filled with buffer gas to a pressure of 0.5 atm and equipped with optical windows for inputting a laser beam and observing the growth of filaments using an external optical microscope. In the chamber, the target is mounted on a holder equipped with a cooling system to cryogenic temperatures. The axis of the laser beam was perpendicular to the surface of the target. At a distance from the target in the chamber there are two metal electrodes on both sides of the axis of the laser beam and parallel to it to create an electric field with a strength of 100-1000 V / cm. After evacuation of the chamber, carbon dioxide was injected into it to a pressure of 0.5 atm.

The known device has a limited scope.

A known method of producing glass nanoparticles (see PCT application WO2008118536, IPC C03B 23/04, published 02.10.2008), in which a glass target is irradiated by a pulsed periodic laser with a short pulse length in a gas at atmospheric pressure or in a liquid cell. Nanoparticles formed during laser ablation are deposited on a substrate.

The potential attractiveness of the formed nanostructures is determined by their increased emissivity, however, the wide dispersion of the sizes of the resulting nanoparticles and the inability to produce metal nanoparticles determine a narrow range of possible applications of the method.

A device for producing glass nanoparticles is known (see PCT application WO 2008118536, IPC С03В 23/04, published October 2, 2008), containing a pulsed laser, a glass target, and a substrate on which the resulting nanoparticles are deposited.

Nanoparticles obtained using a known device have a wide range of sizes. In addition, the device allows to obtain particles from a limited number of materials.

A known method of producing nanoparticles (see patent RU No. 2242532, IPC C23C 4/00, B01J 2/02, published December 20, 2004), comprising dispersing the molten material, feeding the resulting liquid droplets of this material into a plasma formed in an inert gas at a pressure of 10 ^-1 -10 ^-4 Pa, cooling in an inert gas of liquid nanoparticles formed in the plasma to solidify and applying the resulting solid nanoparticles to the carrier, while the plasma parameters satisfy certain ratios. The dispersion of the molten material and the delivery of the obtained liquid droplets into the plasma is carried out by laser ablation of the target or by applying an electric field to the tip cathode of the conductive material. The radius of curvature of the tip is selected no more than 10 μm, and the electric field strength at the tip of the tip is not less than 10 ⁷ V / cm.

Structures fabricated in a known manner are characterized by unique electrical, magnetic and catalytic properties. However, the low productivity of the method and the high cost of the equipment used significantly limit the possibilities of industrial application of the method.

A device for producing nanoparticles is known (see patent RU No. 2242532, IPC С23С 4/00, B01J 2/02, published December 20, 2004), including a chamber filled with an inert gas, in which a tip cathode, an anode with a hole, a cathode with a hole and ring anode on which the substrate is fixed.

When an appropriate potential difference is applied between the tip cathode and the anode, molten droplets fly out from the surface of the cathode, which, flying through the plasma region, divide, forming nanoparticles and larger droplets than nanoparticles.

A known method of producing nanoparticles (see patent RU No. 2265076, IPC С23С 4/00, B01J 2/02, published November 27, 2005), in accordance with which the material is dispersed by applying to the tip cathode of a conductive material with a radius of curvature of the tip of not more than 10 μm of an electric field with a field strength at the tip tip of at least 10 ⁷ V / cm and the resulting liquid droplets of this material are fed into an electric discharge plasma with a pulse duration of at least 10 μs. The plasma is created in an inert gas at a pressure of 10 ^-3 -10 ^-1 Pa between the electrodes with a potential difference of at least 2 kV and is simultaneously exposed to a magnetic field of at least 600 Gs normal to the mentioned electric field creating the plasma. Next, the liquid nanoparticles formed in the plasma are cooled in an inert gas until solidified and the resulting solid nanoparticles are applied to the carrier. The plasma parameters satisfy the given relations.

The advantages of this method compared to the method in which droplets are charged in a plasma of a laser torch is a significant increase in the productivity of the method and a decrease in the cost of the equipment used. At the same time, in order to effectively transform the starting material into a nanostructured state, it is necessary to coordinate the vacuum conditions in the plasma formation chamber and in the droplet source. For this reason, not all methods of dispersing the starting material can be used, which imposes restrictions on the choice of starting materials. For example, difficulties arise when working with refractory metals, for which the most attractive is the use of electrohydrodynamic spraying, which requires the creation of a high vacuum in the chamber.

A known installation for producing nanoparticles (see patent RU No. 2265076, IPC С23С 4/00, B01J 2/02, published November 27, 2005), which includes a vacuum chamber in which are placed: tip cathode, anode with a hole, cathode with a hole and a ring anode on which the substrates are fixed, as well as a block that creates a magnetic field. The chamber is filled with an inert gas at a pressure of 10 ⁻³ −10 ⁻¹ Pa.

The known installation does not allow spraying refractory materials, coordination of vacuum conditions in the plasma forming chamber and in the source of droplets is required.

A known method of producing nanoparticles that matches the claimed technical solution for the largest number of essential features and adopted as a prototype (see M.V. Gorokhov, V.M. Kozhevin, S.A. Gurevich, D.A. Yavsin, ZhTF 2008, vol. 78, issue 9, p. 46). The prototype method includes dispersing the molten material using an electrohydrodynamic source with electron beam melting of the tip surface of the metal anode, feeding the obtained liquid droplets of this material into the electron cloud, cooling the liquid nanoparticles formed during the passage of the electron cloud and solidifying the obtained solid nanoparticles on the substrate. Modes were discovered in which the formation of nanoparticles with a size of 20-30 nm occurred. An analysis of the processes occurring in the prototype method showed that nanoparticles are formed as a result of cascade fission of the initial micron-sized metal droplets emitted from the surface of the anode under the influence of an electric field. It was also shown that the fission of the initial droplets occurs when these droplets pass through an electron beam focused at the surface of the anode. The absence of smaller nanoparticles indicates that the process of recharging particles in a metal chamber practically does not work.

A device for producing nanoparticles is known, which coincides with the claimed technical solution for the largest number of essential features and is taken as a prototype (see M.V. Gorokhov, V.M. Kozhevin, S.A. Gurevich, D.A. Yavsin, ZhTF 2008, Volume 78, Issue 9, p. 46). The device comprises an apparatus for producing nanoparticles (see FIG. 1), consists of three nodes: a microdrop droplet forming unit, a micro droplet recharging unit, and a nanoparticle deposition unit. The microdroplet flow forming unit includes a metal needle, which is an anode, and an annular cathode with a central hole. The microdroplet reloading unit includes a metal grounded casing in the form of a hollow round cylinder with central end openings providing an exit of an electron flow and passage of generated nanoparticles. The nanoparticle deposition site includes a substrate. An electron emitter is installed in the housing, which is made in the form of tungsten spirals connected to a current source.

In the prototype device, the division of the initial droplets occurs when these droplets pass through an electron beam focused at the surface of the anode, so the device allows to obtain particles with a size of at least 20-30 nm.

The objective of the invention is the development of such a method for producing nanoparticles and a device for its implementation, which would allow the formation of nanostructures from nanoparticles of smaller size and with a narrower dispersion of sizes than obtained by the prototype method.

The problem is solved by a group of inventions, united by a single inventive concept.

In terms of the method, the task is solved in that the method of producing nanoparticles involves dispersing the molten material, feeding the formed liquid microdrops of this material into the electron stream to recharge the microdrops to the state where their cascade fission begins, to obtain nanoparticles and applying the resulting nanoparticles to the substrate. To recharge microdrops to the state in which their cascade division begins, the parameters of the electron flow and the residence time of the liquid microdrops in it are selected from the following relationships:

where: r is the radius of the charged liquid droplets, m;

E is the average electron energy, J;

n is the electron flux density, m ^-3 ;

τ is the droplet charging time, s;

σ is the coefficient of surface tension of the dispersible material at its melting temperature, N / m;

e is the electron charge, C;

ε ₀ is the electric constant, f / m;

m _e is the mass of the electron, kg.

The dispersion of the molten material can be carried out by any known method, for example, by electron beam melting of the surface of the tip of a metal anode, in which the electric field strength at the top of the tip of the anode is maintained at a level of at least 10 ⁷ V / cm. It is also possible to disperse the molten material using the laser ablation of the target from any material that can be transferred to a liquid state.

Improving the efficiency of the proposed method compared to the prototype is achieved by increasing the electron energy while satisfying the conditions of sufficient electron flux density and the residence time of the charged liquid droplets in it to enable droplets to be charged to the state in which their cascade division begins.

In terms of the device, the problem is solved in that the device for producing nanoparticles contains a microdroplet with a cathode and anode arranged in a vacuum chamber and coaxially mounted, a microdroplet recharger and a nanoparticle deposition unit with a disk cathode with a central hole, anode and substrate mounted on the anode . The micro-droplet flow forming unit is installed with an axial clearance relative to the micro-droplet recharging unit, around which an annular control electrode is mounted connected to an adjustable voltage source. The microdroplet flow forming unit further comprises a dielectric disk with a central hole, in the annular groove of which an annular cathode is installed, and the anode is made in the form of a metal needle, which is the first anode. The microdroplet recharging unit comprises a dielectric body in the form of a hollow circular cylinder with central end openings, in which a first circular cylindrical cathode and a first circular cylindrical metal grid are installed, which is the second anode, between which the first electron emitter is placed.

In the device, the anode of the nanoparticle deposition unit can be made in the form of a disk, ring or torus.

The microdroplet recharging unit may include a second round cylindrical cathode and a second round cylindrical metal grid, which is the fourth anode, between which there is a second electron emitter installed behind the first electron emitter and separated from it by an annular dielectric partition.

Both the first and second electron emitters can be made in the form of a tungsten filament placed on a circular cylindrical surface and connected to a current source.

In the device, the dielectric disk, the dielectric body, the annular dielectric partition and the disk cathode can have the same radius of the holes.

The control electrode can be made in the form of a ring with a cylindrical or concave inner surface or in the form of a hollow truncated cone.

The essence of the invention lies in the fact that, in contrast to the known prototype method, the parameters of the electron flow into which liquid microdrops are transported are selected based on the requirement of the simultaneous fulfillment of conditions (1) - (2), ensuring cascade fission of all electrons injected into the stream source liquid microdrops of material. The fulfillment of these conditions makes it possible to reproducibly form monodisperse structures consisting of amorphous nanoparticles with a variable, including extremely high, packing density, and efficient conversion of the starting material into nanoparticles is achieved. When implementing the proposed method, the density and average electron energy are selected based on condition (1). When condition (1) was derived, which implies charging the initial microdrops to the threshold of Rayleigh capillary instability (A.I. Grigoriev, S.O. Shiryaeva, ZhTF, 1991 vol. 61, issue 3, p. 19), the charge of the microdrops was calculated using the dependence of the potential of microdrops located in the electron cloud on the average electron energy, taking into account the process of field emission from the surface of a microdrop (see Elinson MI, Vasiliev GF Field emission. M: Fizmatgiz, 1958).

It is also important that expression (1) is valid only in the case when the initial liquid microdrops are in the electron flow for a sufficiently long time, during which their stationary charge state is reached. The stationary state is achieved if condition (2) is fulfilled, which means that the time of flight of microdrops through the volume occupied by the electron flow is longer than their charging to a floating potential. If condition (2) is not fulfilled, then the initial microdrops will not have time to charge during the time spent in the electron flow, and their division will not occur. Thus, the requirement of the joint fulfillment of conditions (1) and (2) is a significant difference from the prototype method, which ensures the involvement in the process of division of all the original microdroplets of the material supplied to the electron stream.

The inventive method for producing nanoparticles is illustrated in the drawing, where:

figure 1 shows a diagram of an installation that implements the inventive method of producing nanoparticles, with one emitter of electrons;

figure 2 shows a diagram of an installation with two electron emitters;

figure 3 shows a diagram of an electron emitter.

A device for producing nanoparticles (see Fig. 1) consists of three nodes: node 1 for forming a droplet flow, node 2 for recharging microdrops and node 3 for nanoparticle deposition. The micro-droplet flow forming unit 1 is installed with an axial clearance relative to the micro-droplet recharging unit 2. The assembly of nodes 1, 2, 3 is placed in a vacuum chamber (not shown in the drawing), the pressure in which does not exceed 10 ^-3 Pa. The microdroplet flow forming unit 1 consists of a metal needle 4, which is the anode, and an annular cathode 5 inserted into the annular groove of the dielectric disk 6 with a central hole 7. The microdroplet recharging unit 2 is a dielectric body 8 in the form of a hollow circular cylinder, into which the first a hollow circular cylindrical cathode 9, as well as a first electron emitter 10 and a first circular cylindrical metal grid 11, which is the second anode. The inner radius of the hollow circular cylindrical cathode 9 is greater than the radius of the grid 11, the emitter 10 is located between the cathode 9 and the metal grid 11. At the ends of the dielectric housing 8 there are central holes 12. The nanoparticle deposition unit 3 consists of a disk cathode 13 with a central hole 14, of the third anode 15 in the form of, for example, a disk and a substrate 16 mounted on the third anode 15. The radii of the holes 7, 12, 14, respectively of the dielectric disk 6, the dielectric body 8 and the disk cathode 13 are preferably the same and different GOVERNMENTAL R, casing length is L. The nodes 1, 2, 3 coaxially collected. Around the gap between the micro-droplet flow forming unit 1 and the micro-droplet recharging unit 2, a control electrode 17 is connected to an adjustable voltage source 18. The control electrode 17 may be in the form of a ring with a cylindrical or concave inner surface. The control electrode 17 can be made in the form of a hollow truncated cone, facing a large base to the metal needle 4. The metal needle 4, the grid 11 and the third anode 15 are connected respectively to the first voltage source 19, to the second voltage source 20 and to the third voltage source 21. The first electron emitter 10 is made (see figure 3) in the form of a tungsten filament 22, in the form of a spiral of tungsten filament placed on a circular cylindrical surface and connected to a current source 23. The microdroplet recharging unit 2 may include (see FIG. 2) a second round cylindrical cathode 24 and a second round cylindrical metal grid 25, which is the fourth anode, between which a second electron emitter 26 is placed, located behind the first electron emitter 10 and separated from it by a ring dielectric the partition 27. The second metal grid 25 is connected to the fourth voltage source 28. Adding a second cylindrical cathode 24, a second cylindrical grid 25 and a second electron emitter 26 is intended for monitoring the point in space at which the division of the drops occurs. Moving this point to the area of the hole 14 leads to increased reproducibility and productivity of the process. In order to separate the resulting nanoparticles from larger residues of unfinished microdrops, the third anode 15 can be made in the form of a ring or a torus. This embodiment of the third anode 15 makes it possible to reduce the dispersion of nanoparticle sizes in the structures formed.

The inventive method for producing nanoparticles is as follows. The molten material from which it is necessary to obtain nanoparticles is dispersed in the microdroplet flow forming unit 1 by any known method (for example, by electrohydrodynamic spraying). The obtained liquid microdroplets of this material are charged in the micro-droplet recharging unit 2 by a stream of high-energy electrons to the limit at which the microdroplets begin to divide. The nanoparticles formed during microdroplet division are deposited on a substrate 16, which can be any solid material. As the authors established, the parameters of the electron flow and the residence time of liquid microdrops in it must satisfy the relations:

In the case of applying the method of electrohydrodynamic sputtering of the tip anode, the potential difference between the metal needle 4 and the ring cathode 5 in the node 1 of the formation of the flow of microdrops U ₀ must satisfy the ratio

where r _c is the outer radius of the disk cathode 5, m;

r _a is the radius of the metal needle 4, m;

L ₀ is the distance from the end of the metal needle 4 to the plane of the disk cathode 5, m

The potential difference U between the cylindrical cathode 9 and the cylindrical metal mesh 11 in the micro-droplet recharging unit 2 is selected in accordance with the requirement of the formula (1) of the proposed method and must satisfy the ratio

the emission current of electrons in the node 2 recharging microdrops I, A, is selected in accordance with the requirement of formula (2) of the proposed method and must satisfy the ratio

The potential difference U ₁ between the disk cathode 13 and the ring anode 15 in the node 3 of the deposition of nanoparticles must satisfy the ratio

where L ₁ is the distance from the plane of the disk cathode 13 to the plane of the annular focusing anode 15, m;

4 · 10 ⁴ - proportionality coefficient, V / m.

The potential difference between the disk cathode 5 and the regulating ring anode 17 is selected so that the current flowing through the metal needle 4, satisfies the ratio

where χ is the thermal conductivity of the material, W / (m · K)

T _m is the melting temperature of the conductive material, K;

4,5 · 10 ^-8 is the coefficient of proportionality, W / (m ² · K ⁴ ).

When a second cylindrical cathode 24, a second cylindrical grid 25 and a second electron emitter 26 are added, the potential difference U between the cylindrical cathode 9 and the cylindrical metal grid 11 decreases to

and the potential difference U ₂ between the second cylindrical cathode 24 and the second cylindrical metal grid 25 is chosen equal

Example. A method was implemented for producing copper nanoparticles from microdrops charged by a stream of high-energy electrons. In this case, microdroplets were created by the method of electrohydrodynamic sputtering of a copper tip cathode 300 μm thick. The electron flux was created in the microdroplet recharging chamber upon acceleration of electrons emitted by a set of tungsten spirals into the gap between a continuous cylindrical cathode and a cylindrical anode-grid, the potential difference between which was 1.2 kV, which ensured that condition (1) was satisfied. The obtained nanoparticles were deposited on the surface of a substrate located at the outlet of the microparticle recharge chamber. The radius of the holes of the disk cathode and the dielectric casing of the recharging chamber is R = 0.5 cm, and the length of the dielectric casing is L = 10 cm. For these dimensions of the dielectric casing, condition (2) is determined by choosing the emission current from the surface of the tungsten spirals, which was chosen to be I≈2 BUT.

Using the process parameters described above, copper nanoparticles 5 nm in size were obtained on an oxidized silicon substrate. Note that when the accelerating potential in the recharging chamber was turned off, the size of the nanoparticles deposited on the substrate was not less than 20-30 nm.

Claims (15)

1. A method of producing nanoparticles, including the dispersion of molten material, feeding the formed liquid microdrops of this material into an electron stream to recharge the microdrops to the state in which they cascade division, to obtain nanoparticles and applying the resulting nanoparticles to a substrate, characterized in that for recharging the microdrops to the state in which their cascade fission begins, the parameters of the electron flow and the residence time of the liquid microdroplets in it are selected from the following relations:

;

;
where r is the radius of the charged liquid droplets, m,
E is the average electron energy, J,
n is the electron flux density, m ^-3 ,
τ is the droplet charging time, s,
σ is the coefficient of surface tension of the dispersible material at its melting temperature, N / m,
e is the electron charge, C,
ε ₀ - electric constant f / m,
m _e is the mass of the electron, kg. 2. The method according to claim 1, characterized in that the molten material for dispersion is obtained by electron beam melting of the surface of the tip of the metal anode at an electric field strength at the top of the tip of the anode, maintained at a level of at least 10 ⁷ V / cm. 3. The method according to claim 1, characterized in that the molten material for dispersion is obtained by laser ablation of a target from a material transferred to a liquid state. 4. A device for producing nanoparticles, containing placed in a vacuum chamber and coaxially mounted unit for forming a flow of microdrops with a cathode and anode, a microproplet recharging unit and a deposition unit for nanoparticles with a disk cathode with a central hole, anode and substrate mounted on the anode, characterized in that the micro-droplet flow forming unit is installed with an axial clearance relative to the micro-droplet recharging unit, around which an annular control electrode is mounted connected to an adjustable voltage source In this case, the microdroplet flow forming unit further comprises a dielectric disk with a central hole, in which an annular cathode is installed in the annular groove, and the anode is made in the form of a metal needle, which is the first anode, the microdroplet recharging unit contains a dielectric body in the form of a hollow round cylinder with central end holes, in which the first round cylindrical cathode and the first round cylindrical metal grid are installed, which is the second anode, between which The first electron emitter. 5. The device according to claim 4, characterized in that the anode of the nanoparticle deposition site is made in the form of a disk. 6. The device according to claim 4, characterized in that the anode of the nanoparticle deposition site is made in the form of a ring. 7. The device according to claim 4, characterized in that the anode of the nanoparticle deposition site is made in the form of a torus. 8. The device according to claim 4, characterized in that the first electron emitter is made in the form of a tungsten filament placed on a circular cylindrical surface and connected to a current source. 9. The device according to claim 4, characterized in that the micro-droplet recharging unit further comprises a second circular cylindrical cathode and a second circular cylindrical metal grid, which is the fourth anode, between which there is a second electron emitter installed behind the first electron emitter and separated from it by a ring dielectric septum. 10. The device according to claim 9, characterized in that the second electron emitter is made in the form of a tungsten filament placed on a round cylindrical surface and connected to a current source. 11. The device according to claim 9, characterized in that the dielectric disk, the dielectric housing, the annular dielectric partition and the disk cathode are made with the same radius of the Central holes. 12. The device according to claim 4, characterized in that the control electrode is made in the form of a ring. 13. The device according to p. 12, characterized in that the control electrode is made in the form of a ring with a cylindrical inner surface. 14. The device according to p. 12, characterized in that the control electrode is made in the form of a ring with a concave inner surface. 15. The device according to claim 4, characterized in that the control electrode is made in the form of a hollow truncated cone.

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