RU2756051C1 - Device for producing nanoparticles from gases and vapors of liquids at ultra-low temperatures - Google Patents

Abstract

FIELD: nanotechnology.SUBSTANCE: invention relates to the field of nanotechnology, namely, the proposed device makes it possible to obtain small particles (nanoparticles) from materials that exist at room temperatures in the form of gases or vapors. The device for producing nanoparticles from materials existing at room temperature in the form of gases and vapors of liquids includes a helium cryostat with windows, a condensation tube, an ampoule for collecting nanoparticles. The ampoule for collecting nanoparticles contains superfluid helium. The level of superfluid helium in the ampoule is maintained by a cryopump through an additional supply tube. The condensation tube is made with the possibility of supplying an impurity-helium mixture.EFFECT: invention makes it possible to avoid losses of the condensed flow and increase the nanoparticle collection time.1 cl, 1 dwg

Description

The invention relates to the field of nanotechnology, namely, the proposed device makes it possible to obtain small particles (nanoparticles) from materials existing at room temperatures in the form of gases or vapors, the condensation of which is carried out on the surface of a superfluid liquid.

The device contains a cryostat with superfluid helium as a low-temperature substrate for condensation of nanoparticles, a tube for supplying a mixture of helium and the required impurity, an ampoule for collecting nanoparticles, a device for maintaining the level of superfluid helium above the end of the tube for creating a low-temperature substrate for condensation of nanoparticles on the surface of superfluid helium and preventing losses mixtures during the formation of nanoparticles.

A device and method for producing nanoparticles in a continuous mode is known, consisting of several reactors with a heated reaction zone, with the transfer of material sequentially from reactor to reactor using a propulsion device (K. Nues, A. Vootsch, M. Groualle, J. Eshves, F. Darvas, Patent 2486003). The device is characterized in that after each heated reaction zone, a corresponding cooling device is installed in the material flow channel to reduce the size of nanoparticles in the process of their production, and the cooling devices are additionally configured to stop this process of nanoparticle production.

The device is suitable for the synthesis of nanoparticles from one, two or more constituents, preferably metals; nanoparticles, nanoemulsions, nanosuspensions and colloidal solutions containing biologically active organic molecules, as well as nanoparticles with a core-shell structure.

A device for producing metal powders was used as a prototype (DS Belinin, PS Kuchev, Yu.D. Shchitsyn, NN Strukov, RF Patent 2532215). The device contains a water-cooled working chamber with a controlled atmosphere, a plasmatron installed in the upper part of the working chamber for forming a plasma flow, one or more devices for feeding bar material into the plasma flow, and a powder collector installed in the lower part of the working chamber. Provides the production of spherical powders in the absence of particle adhesion. The invention relates to the field of obtaining metal powders using plasma spraying.

The disadvantages of the prototype are the impossibility of forming nanoparticles from substances that exist at room temperatures in the form of gases or vapors and for substances decomposed by plasma spraying (a fundamentally different class of substances).

The common features of the devices described above and the device we propose is the creation of an atomic or molecular flux of impurity atoms in a controlled atmosphere, condensed onto a cold surface, which makes it possible to form nanoparticles. The applied atmosphere allows the creation of conditions that limit the growth of particles.

The technical result, which the claimed invention is aimed at, is to obtain nanoparticles from materials that exist at room temperatures in the form of gases or vapors or substances that do not allow heating to high temperatures, the device avoids losses of condensed matter and increases the amount of nanoparticles formed.

To achieve this technical result, a helium cryostat was used, a quartz condensation tube with a diameter of 2 cm was manufactured, which allows directing a mixture of material for the preparation of nanoparticles and gaseous helium onto the surface of superfluid helium from the upper part of the cryostat, the upper end of the condensation tube is at room temperature and is connected to the system preparation of the mixture, a quartz ampoule in which the formed nanoparticles are collected and the level of superfluid helium in which is located above the end of the condensation tube. The level of superfluid helium in the ampoule is maintained using our proposed helium filling system, which consists of a cryopump and a filling tube.

The main differences from the prototype are that the flow of atoms is not formed by plasma heating of a metal target in a controlled atmosphere, which is unsuitable for this class of substances, but is prepared in advance by mixing an impurity gas and helium. To create a flow of impurity atoms existing at room temperature in the form of a liquid, the liquid is bubbled with a flow of helium gas, the concentration of liquid vapors in the finished mixture is determined by the temperature of the liquid. Helium is used as a controlled and cooling atmosphere. An impurity-helium mixture prepared in this way is directed to a cold surface, however, unlike the prototype, this is a surface of superfluid helium, which is determined by the class of substances used to form nanoparticles in this device. In this case, the vapor pressure of superfluid helium satisfies the conditions for the formation of a laminar flow of a mixture that is cooled during condensation in times of the order of tens of seconds. Another fundamental difference from the prototype is the presence of a cryopump, which maintains a constant level of superfluid liquid to condense the entire mixture flow, which eliminates the possibility of flow losses during condensation and increases the accumulation time of nanoparticles in the collection ampoule.

FIG. 1 shows: 1 - helium cryostat with vacuum insulation, 2 - windows, 3 - condensation tube, 4 - ampoule for collecting nanoparticles, 5 - bar, 6 - cryopump, 7 - filling tube, 8 - impurity-helium mixture flow, 9 - condensed nanoparticles, 10 is the helium level in the ampoule, 11 is the helium level in the cryostat, 12 is the superfluid helium flow, 13 is a fine powder, 14 is a heater.

During the operation of the device, the flow of an impurity-helium mixture (8) is fed through a condensation tube (3) to the surface of superfluid helium in an ampoule (4), the level of which in the ampoule is kept constant (10) above the end of the condensation tube to prevent losses of the condensed mixture. A mixture of a small amount (of the order of several percent) of an impurity (for example, gases: deuterium, methane, nitrogen or water vapor, heavy water, alcohol, etc.) and gaseous helium in the process of moving along the condensation tube in times of the order of several tens of seconds is cooled from room temperature to helium and forms nanoparticles (9), while helium atoms prevent the formation of large particles. In the process of cooling the mixture, intense evaporation of superfluid helium occurs, which lowers the level of helium in the ampoule. If the helium level is below the lower end of the condensation tube, the condensation process stops. To maintain a constant level of superfluid helium in the ampoule above the end of the condensation tube, we used a cryopump (6). The principle of operation of the cryopump is based on the ability of the superfluid component to flow through small gaps between the particles of fine powder (13), while the normal component of helium (after heating by the heater (14) in the upper part of the cryopump and the transition of the superfluid component to the normal one) has a large hydraulic resistance at moving through the powder. Due to the increased pressure in the cryopump, superfluid helium rises up the filling tube (8), which makes it possible to add helium to the ampoule (4), despite the fact that the helium level in the cryostat (11) can be significantly lower than in the ampoule (10 ). The use of such a device as cryonancer increases the accumulation time of nanoparticles and increases the yield of the finished product.

Claims (1)

A device for producing nanoparticles from materials existing at room temperature in the form of gases and vapors of liquids, including a helium cryostat with windows, a condensation tube made with the possibility of supplying an impurity-helium mixture, an ampoule for collecting nanoparticles, characterized in that the ampoule for collecting nanoparticles contains into superfluid helium and the level of superfluid helium in the ampoule is maintained by a cryopump through the filling tube.

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