JPH078792A - Production of superfine particle - Google Patents

Abstract

PURPOSE:To provide a method for easily and efficiently producing and collecting superfine particles wherein unevenness of distribution of particle diameter is small by increasing the nonlinear effect of the superfine particles. CONSTITUTION:Material 2 becoming the raw material of superfine particles is irradiated and heated with laser beams 4 in a vacuum vessel 1 into which inert gas has been introduced. A part of movement of the generated vapor or superfine particles formed from the generated vapor is disturbed by a shielding body 3. Superfine particles are collected by disposing a base plate 5 in such a position in the vacuum vessel 1 that the vapor or the superfine particles traveling straight are not reached.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing ultrafine particles utilizing a non-linear effect, and more particularly to a method for producing ultrafine particles having a small variation in particle size distribution.

[0002]

2. Description of the Related Art Ultrafine particles are known to have properties different from those of bulk, and are expected to be applied as functional materials. For example, in compound semiconductor ultrafine particles such as CdS, the band structure becomes discrete as the particle size becomes smaller, and so-called quantum size effect such as shift of the absorption edge to the high energy side occurs (for example, AJ Nozi).
c et al. J. Phys. Chem. , 89,
397 (1987)).

It is known that such a material having a quantum size effect has a large non-linear optical effect,
It can be applied to optical control devices using nonlinear optical effects such as ultrafast optical switches and optical logic devices.

A so-called gas evaporation method is known as a method for producing ultrafine particles. This manufacturing method is a method of heating and evaporating a substance in an inert gas such as Ar, colliding the vapor with the inert gas to lose kinetic energy, and rapidly cooling to form ultrafine particles.

In order to use the manufactured ultrafine particles in a light control element or the like, it is necessary to collect them by some method, and some evaporation methods in gas have conventionally been used (for example, some collection methods). , Superfine handbook, supervised by Shinroku Saito, 1990, Fuji Techno System).

When ultrafine particles are used as a non-linear optical material, the magnitude of the non-linearity is closely related to the wavelength of light used and the particle size of the ultra-fine particles, and the non-linearity is most significant for light of a certain energy. There is an increasing particle size (hereinafter referred to as "optimal particle size"). Therefore, in order to obtain a material with a large non-linearity at the target wavelength of light, the proportion of ultrafine particles with an optimum particle size should be increased and the variation in particle size centered on that optimum particle size should be kept low. There must be.

Fine particles having a particle size larger than the optimum particle size have their optical absorption edges shifted to the lower energy side than the optical absorption edges of the fine particles having the optimum particle size due to the quantum size effect. Not only is the particle size not optimal for the light to be emitted, but it is necessary to make the ratio particularly small in order to increase the absorption coefficient in the light and reduce the magnitude of the effective nonlinearity.

As described above, the particle size distribution of ultrafine particles is
It is desirable that the ratio of the fine particles having the optimum particle size is the maximum, and the distribution is as small as possible, and in particular, the ratio of the fine particles having a particle size larger than the optimum particle size is as small as possible. When collecting ultrafine particles, it is desired to collect ultrafine particles having such a particle size distribution.

Regarding the operation of selecting only ultrafine particles of a certain size (hereinafter referred to as “classification”), various methods have been proposed for classifying fine particles having a relatively larger particle size than ultrafine particles having a particle size of 1 μm or more. However, some methods have already been put to practical use. The most general method among them is a classification method which utilizes the fact that the fine particles are moved together with the gas flow and the inertial force of the fine particles and the diffusion distance in the gas differ depending on the size of the fine particles.

Even in the collecting method conventionally used in the gas evaporation method for producing ultrafine particles, it is recognized that the size of the particles tends to be small as a whole when collected in the vicinity of the evaporation source.

However, this difference is not sufficient to improve the effective nonlinearity because the difference in size between the ultrafine particles is not so large, and it cannot be said to be practical.

Therefore, for ultrafine particles having a diameter of several nm to several tens of nm, a classification method using an electric field called electrostatic classification has been devised (for example, superfine particle handbook supervised by Shinroku Saito, 1990, Fuji Techno). system).

As shown schematically in FIG. 3, an electrostatic classifier in which a high-voltage DC power supply 16 is connected to an electrode 15 inserted in a low-pressure container 14 is charged with charged ultrafine particles 17 together with sheath air 18 at a constant pressure. By applying an electric potential opposite to that of the ultra-fine particles to the electrode while sending in, an electrostatic attractive force is applied to the ultra-fine particles passing through the vessel, and the inertia of the ultra-fine particles differs depending on its mass, that is, the particle size. It is a method of collecting by classifying according to the diameter.

[0014]

However, the classification method utilizing the electrostatic attraction has some problems as described below.

That is, in order to perform classification by utilizing electrostatic attraction, it is necessary to charge ultrafine particles by some method, but ultrafine particles having a diameter of several 10 nm or less are difficult to be charged. The proportion of particles that are not charged increases, and as a result, the proportion of particles that can be classified is very small. Further, there is a problem that the accuracy of classification is lowered when the ultrafine particle concentration is increased, and the amount of ultrafine particles that can be processed is very small. Further, as shown in FIG. 3, various additional devices such as a high-voltage DC power supply and electrodes are required to perform electrostatic classification, and the operation is complicated.

As described above, the electrostatic classification method has a problem that it is not practical because it is a classification method capable of treating a large amount of ultrafine particles without waste and with a simple device and operation.

As a result, the particle size of 10 in the gas evaporation method was obtained.
In the production of ultrafine particles having a particle size of nm or less (particularly, a particle size of 20 nm or less), it is the actual situation that the produced ultrafine particles are collected without any classification treatment, and have the above desirable particle size distribution. A method for producing ultrafine particles by a gas evaporation method has not been sufficiently established in practice.

[0018]

The above-mentioned conventional problems can be solved by the following method.

That is, in the in-gas evaporation method, a part of the movement of the ultrafine particles from the raw material of the ultrafine particles is obstructed by the shielding object, so that the ultrafine particles which go straight or the vapor forming the ultrafine particles arrives. Forming a space that does not
A method for producing ultrafine particles, characterized in that ultrafine particles are collected in the space.

The vapor, which is the raw material for the ultrafine particles generated in the inert gas, moves from the heating material as the source of the ultrafine particles at a constant speed and collides with the inert gas. At this stage, the vapor is rapidly cooled to form ultrafine particles, and the formed ultrafine particles change their moving speed and direction due to collision with the inert gas.

Here, considering how ultrafine particles having different particle diameters change their moving directions through the process of collision with an inert gas, if the speeds are the same, the ultrafine particle diameters are the same. That is, the larger the mass, the larger the momentum and kinetic energy. Therefore, as is naturally derived from the mechanical law, the larger the particle size, the smaller the amount of change in direction due to collision.

As described above, in general, due to collisions with other particles, it becomes more difficult for the ultrafine particles having a larger particle size to change its direction. This tendency is due to movement from ultrafine particle groups having various directions. When a group of ultra-fine particles whose direction is limited to a certain range is extracted and compared, the direction of each ultra-fine particle before the collision is limited to a certain range. To reflect more accurately.

Therefore, for example, as shown in FIG.
If the movement of the ultrafine particles is partially controlled by the shielding plate 3 and the movement direction of the ultrafine particles is limited to a certain range to collide with the inert gas, the density distributions of the large particles and the small particles are significantly different. become.

Ultrafine particles can be classified by utilizing such a difference in density distribution. For example, in the case of FIG.
When the substrate is installed at the position A, the number of small ultrafine particles is relatively reduced here, so that the ratio of large ultrafine particles is larger than the original size distribution of the ultrafine particles. On the contrary, if ultrafine particles are collected at the position 5B in FIG.
Since the number of large ultrafine particles is relatively small here, the ratio of small ultrafine particles increases.

However, when the ejected ultrafine particles are collected at a position where they can go straight and reach as shown in 5A of FIG. 4, large ultrafine particles are included, so that the ultrafine particles are used as a nonlinear optical material or the like. When doing so, it is not preferable. Therefore, in this case, as shown in 5B of FIG. 4, it is necessary to collect the ultrafine particles ejected into the gas at a position where they cannot go straight and reach.

The ultrafine particle shielding plate is not limited to the one having one opening as shown in FIG. 4, but may be any object capable of effectively shielding a part of the movement of the ultrafine particles.

The effect of classification according to the present invention varies depending on various factors described below.

First, the classification effect does not work effectively unless the initial velocity (hereinafter simply referred to as "initial velocity") when the ultrafine particles are ejected into the gas is relatively large. This is because when the initial velocity is small, the ultrafine particles immediately reach an equilibrium state due to collision with an inert gas and only exhibit isotropic diffusion due to Brownian motion.

Secondly, the control of the spread of the ultrafine particles in the direction of the initial velocity is also an important factor. If this control is not sufficient, a sufficient classification effect cannot be obtained. This is because the effect of the difference in particle size is less likely to appear even by collision with an inert gas as a whole.

Thirdly, since the influence of the collision on the velocity magnitude and direction of the ultrafine particles changes depending on the pressure of the inert gas and the type of gas, the distance that each ultrafine particle can reach (the distance to reach the equilibrium state) ) And the divergence angle of ultrafine particles change.

When these factors change, the size of the obtained ultrafine particles changes even if they are collected at the same position.
Therefore, the collection speed of the ultrafine particles is changed according to the initial velocity of the ultrafine particles, its spread, the type and pressure of the inert gas used, or the initial velocity of the ultrafine particles, its spread, and the inert gas used. It is necessary to collect the ultrafine particles at a position where the relative density of the ultrafine particles of the desired size is the highest by changing the type and pressure of.

When a high energy laser is used as a heating source in the gas evaporation method, the ultrafine particles form at least several tens of particles in the direction perpendicular to the target of the raw material.
It is known to fly at 0 m / sec, and the initial velocity of ultrafine particles can be increased. Further, it is possible to widen the range of adjustment of the initial velocity of the ultrafine particles.

Other heating sources such as a resistance heating method can be used, but since the initial velocity of the ultrafine particles is smaller than that when a high energy laser is used as the heating source, the collection position of the ultrafine particles is used as the raw material in this case. Ingenuity is needed to bring it closer to the material.

Another method of colliding the ultrafine particles of various sizes produced by the in-gas evaporation method with an inert gas at a speed and a degree of extent that the classification effect effectively works is shown in FIG. As described above, the ultrafine particle generation container 9 for generating ultrafine particles by the gas evaporation method, the ultrafine particle collection container 10 for collecting the ultrafine particles, and the ultrafine particle transport pipe 11 having pores connecting the internal spaces of these containers There is a method for producing ultrafine particles using an apparatus composed of (hereinafter referred to as "orifice").

According to this manufacturing method, the ultrafine particle generating container 9 is directed from the orifice 11 toward the ultrafine particle collecting container 10.
Ultrafine particles formed by heating and evaporation of the material inside and collision with the inert gas pass through the orifice 11 due to the internal pressure difference of the inert gas between the ultrafine particle generation container 9 and the ultrafine particle collection container 10. The particles are introduced and collected in the fine particle collection container 10.

Here, the movement of the ultrafine particles when being introduced into the ultrafine particle collection container 10 is controlled within a certain range by the inner diameter of the orifice 11 or the like, and
Since the initial velocity can also be maintained at a constant velocity or higher by the flow rate of the inert gas passing through the orifice, the ultrafine particles introduced into the ultrafine particle collecting container 10 collide with the inert gas in the container, The particle size will change the density distribution.

Therefore, the collection of the ultrafine particles in the ultrafine particle collecting container 10 is performed by the orifice 11 as shown in FIG.
By carrying out with the substrate 5 in a position where the ultrafine particles introduced from the above cannot go straight, only the ultrafine particles having a certain particle diameter or less can be collected from the formed ultrafine particles.

[0038]

According to the method for producing ultrafine particles of the present invention, ultrafine particles having a large variation in particle size distribution produced by the gas evaporation method are jetted into an inert gas, and the ultrafine particles are made to collide with the inert gas, Since the density distribution of ultrafine particles varies depending on the particle size, it becomes possible to selectively collect the ultrafine particles according to the particle size, and as a result, the dispersion of the particle size distribution of the ultrafine particles can be reduced. it can.

According to the present invention, in order to reduce the variation in the particle size distribution of the ultrafine particles, there is a change in the velocity of movement of the ultrafine particles which is naturally derived from the mechanical law at the time of collision between the ultrafine particles and the inert gas. Since the particle size dependence of the direction change is merely utilized, it is necessary to perform a secondary treatment that is difficult and inefficient for ultrafine particles such as charging the ultrafine particles as in the conventional method. In addition, the apparatus and operation are simple, and a large amount of ultrafine particles having a desired particle size distribution can be produced.

[0040]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 shows a schematic view of a manufacturing apparatus used for manufacturing ultrafine particles in Embodiment 1. This apparatus includes a vacuum container 1 for producing ultrafine particles in a gas, a material 2 as a raw material for ultrafine particles, an ultrafine particle shielding object 3, a laser beam introduction window 4A, a substrate 5 for collecting ultrafine particles, The substrate holder 6 and the inert gas introducing pipe 7 are provided. The vacuum container 1 is connected to an exhaust system via a gate valve 8, and the substrate holder 6 is movable so that its position and angle can be changed. Thereby, it is possible to collect fine particles at various positions in the vacuum container. The shielding object 3 has one rectangular opening 3A of 1.5 cm × 0.4 cm.

In a state where the vacuum container 1 is filled with an inert gas, the surface of the material 2 which is the raw material of the ultrafine particles is irradiated with the high energy laser light 4 through the above-mentioned opening to vaporize the raw material, and this vapor is inactive. Collisions with gas produce ultrafine particles. The produced ultrafine particles are emitted in a direction substantially perpendicular to the surface of the material 2 as a raw material together with the vapor which has not formed the ultrafine particles, and are ejected into the gas through the opening. The size of the ultrafine particles ejected in the gas varies in the direction of scattering, so the substrate holder 6
As shown in FIG. 1, for example, the position of is set to a position where the ultrafine particles cannot go straight from the material 2 which is the raw material of the ultrafine particles, so that there is a variation smaller than the original particle size distribution. Ultrafine particles can be collected on the substrate.

A method for producing CdTe ultrafine particles using this apparatus will be described. A disc-shaped CdTe with a diameter of 5 cm and a thickness of 0.5 cm is used as a raw material for the ultrafine particles.
A polycrystalline target was used. Vacuum container 1 to 5 × 10 ^-6 T
After evacuation to about orr, the gate valve 8 was closed, Ar gas was introduced from the inert gas introducing pipe 7, and the pressure was adjusted to about 0.5 Torr. In this state, the target is irradiated with the second harmonic of the Nd: YAG pulse laser (wavelength 532 nm, laser light intensity 25 J / cm ² , repetition frequency 10 Hz) through the laser light introduction window 4.
The CdTe target was evaporated. The target was rotated at a speed of about 24 rpm during evaporation by the rotation introducing mechanism so that the same position on the target was not continuously irradiated with laser light. Change the position of the substrate holder 6,
Ultrafine particles were collected at various positions in the vacuum container 1. In order to directly observe the collected ultrafine particles, a microgrid for electron microscope observation was used as a substrate. Also,
The number of times of pulsed laser irradiation was 50 shots for each position of the substrate holder.

When the CdTe ultrafine particles collected at the positions 5C and 5D in FIG. 5 were observed by a transmission electron microscope and the distribution of the respective particle sizes was examined, the results shown in FIGS. 6 and 7 were obtained. Was obtained. The position 5C in FIG. 5 is a position where the ultrafine particles can fly straight forward from the evaporation source, while the position 5D in FIG. However, there is a difference that you cannot go straight and fly. Comparing FIG. 6 and FIG. 7, the variation in the particle size distribution is obviously changed, and the ultrafine particles collected at the position 5D have a smaller concentration of large particles and the variation in the particle size distribution is smaller. You can see that

From the result of electron microscope observation, it was also confirmed that the collected CdTe ultrafine particles were crystallized.

When the CdTe ultrafine particles collected at the collection positions 5C and 5D in FIG. 5 were dispersed in glass and the light absorption characteristics thereof were measured, the results shown in FIG. 8 were obtained. In the case of ultrafine particles collected at the 5D position, near the absorption edge (6
Absorption shoulder is observed at around 00 nm), while 5
Such a shoulder is not observed in the ultrafine particles collected at the position C, and the absorption edge is also shifted to the longer wavelength side compared to 5D. Since such a change is caused by the so-called quantum size effect, the shape near the absorption edge is closely related to the variation in the average particle size and particle size distribution of ultrafine particles, and generally,
It is known that the shoulder-like structure near the absorption edge is observed only when the variation in particle size distribution is small. Therefore, the results of the optical absorption measurement shown in FIG. 8 also show that the dispersion of the particle size distribution of the ultrafine particles produced according to the present invention is small.

This time, the CdTe ultrafine particles have been described, but the present invention is not limited to this, and for example, 2-6 group compound semiconductors such as CdSe and ZnSe, GaAs and In.
3-5 group compound semiconductors such as P and InGaAsP, S
Various semiconductors such as Group IV semiconductors such as i and Ge,
The method for producing ultrafine particles of the present invention can be applied to various materials that can be produced by the gas evaporation method, such as metals such as gold and silver, magnetic materials containing Fe and Co, and the like.

Also, this time, an example using a high power pulsed laser beam as a heating source of the raw material in the vaporization method in gas was described, but the present invention is not limited to this, and it may depend on induction heating, resistance heating, and pressure in the evaporation container. Various methods such as electron beam heating and arc discharge can be applied.

(Embodiment 2) Next, FIG. 2 shows a manufacturing apparatus used for manufacturing ultrafine particles in Embodiment 2.

The present apparatus comprises an ultrafine particle generating container 9, an ultrafine particle collecting container 10 and an orifice 11 connecting these two containers. The ultrafine particle generation container 9 is provided with a material 2 as a raw material of ultrafine particles, a laser beam introduction window 4A and an inert gas introduction pipe 7, and the evaporation chamber is filled with an inert gas as in the first embodiment. In this state, the target 2 is irradiated with the high-energy laser beam 4 to produce ultrafine particles. The ultrafine particle collecting container 10 includes a substrate 5 for collecting ultrafine particles and a substrate holder 6 for holding the substrate 5.
And is connected to the exhaust system via the conductance variable valve 12. The substrate holder 6 is the first embodiment.
It is also movable like the, and its position and angle are variable. Thereby, it is possible to collect the fine particles at various positions in the ultrafine particle collecting container 10. Orifice 11
The inner diameter of is a parameter that determines the velocity of the ultrafine particles at the outlet, that is, the magnitude of the initial velocity of the ultrafine particles. In this embodiment, the inner diameter was 0.5 cm.

An inert gas introducing pipe 7 is attached to the ultrafine particle generating container 9.
Ar gas is introduced through the chamber, and the conductance variable valve 12 controls the pressures of the ultrafine particle generation container 9 and the ultrafine particle collection container 10 to 0.5 Torr and 0.05, respectively.
It was adjusted to be Torr. In this state, the material 2 as a raw material for the ultrafine particles was irradiated with a laser beam 4, heated and evaporated, and rapidly cooled by collision with an inert gas to produce ultrafine particles. The ultrafine particles pass through the orifice 11 and are transported to the ultrafine particle collecting container 10 together with the inert gas. During the passage of the orifice 11, the velocity of the ultrafine particles and the velocity of the inert gas are substantially equal. The speed of ultrafine particles in the orifice calculated from the Ar gas flow rate and the inner diameter of the orifice is about 100 m / sec. Therefore, at the exit of the orifice, the ultrafine particles are about 100 m / se.
It is introduced into the ultrafine particle collection container 10 at a speed of c. As in Example 1, since the ultrafine particles jetted into and collided with the inert gas have different spreads in the direction of movement depending on their sizes,
As shown in FIG. 2, for example, the position of the substrate holder 6 is transported through the orifice 11 so that the ultrafine particle collecting container 10 is transported.
By setting the ultrafine particles to be introduced in the position where they cannot go straight, the ultrafine particles having a variation smaller than the original particle size distribution can be collected on the substrate.

A method for producing CdTe ultrafine particles using this apparatus will be described. 5 cm in diameter as raw material for ultrafine particles
A disk-shaped CdTe polycrystal target having a thickness of 0.5 cm was used. After vacuuming the vacuum container 1 to about 5 × 10 ⁻⁶ Torr, Ar gas is introduced from the inert gas introducing pipe 7, and the conductance variable valve 12 is used to control the pressure of the ultrafine particle generating container 9 and the ultrafine particle collecting container 10. Were adjusted to 0.5 Torr and 0.05 Torr, respectively. In this state, the second harmonic of the Nd: YAG pulse laser (wavelength 532 nm, laser light intensity 2
Irradiation with 5 J / cm ² and repetition frequency 10 Hz, Cd
The Te target was evaporated to produce ultrafine particles. The material 2 which is the raw material of the ultrafine particles is being evaporated by the rotation introduction mechanism 2
It was rotated at a speed of about 4 rotations / minute so that the laser beam 4 was not continuously applied to the same position. The manufactured ultrafine particles were introduced into the ultrafine particle collection container 10 together with Ar gas through the orifice 11, the position of the substrate holder 6 was changed, and the ultrafine particles were collected at various positions. In order to directly observe the collected ultrafine particles, a microgrid for electron microscope observation was used as a substrate.

When the collected ultrafine particles were observed with a transmission electron microscope at a position where the straight-moving ultrafine particles could not reach as shown in FIG. 2, the ultrafine particles collected here were the same as in Example 1. Revealed that the concentration of the apparently large particles decreased, and the variation in the particle size distribution was smaller at the points on the axis of the orifice pores than the collected ultrafine particles.

When the collected ultrafine particles were dispersed in glass and the optical absorption characteristics were measured, a quantum size effect was observed and an absorption shoulder near the absorption edge was observed as in Example 1. . Therefore, it was confirmed from the results of optical absorption measurement that the dispersion of the particle size distribution of the ultrafine particles produced by the production method of the present invention was small.

[0055]

According to the production method of the present invention, since ultrafine particles having a particle size of several tens of nm or less produced by the in-gas evaporation method can be selectively collected according to the particle size, the ultrafine particles are subjected to nonlinear optical When used as a material or the like, the optical nonlinearity per unit concentration of ultrafine particles increases.

In particular, it is possible to exclude fine particles having a particle diameter larger than the optimum particle diameter at the light wavelength used, and the effect of reducing the optical nonlinear effect of such fine particles can be effectively eliminated.

Since the production method of the present invention can be carried out without depending on whether or not the ultrafine particles are charged, as compared with the electrostatic classification method, a large amount of ultrafine particles can be operated at a time with a simple device and operation. Can be classified.

Furthermore, in the electrostatic classification method, ultrafine particles that can be classified are limited to a certain proportion of ultrafine particles that can be charged, but in the method according to the present invention, even ultrafine particles that are difficult to be charged can be charged. Since the ultrafine particles can be classified without any trouble, the classification efficiency is good, and as a result, a good particle size distribution with little variation can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic view of an apparatus used for manufacturing ultrafine particles of Example 1 of the present invention.

FIG. 2 is a schematic diagram of an apparatus used for manufacturing ultrafine particles of Example 2 of the present invention.

FIG. 3 is a schematic view of an example of an apparatus used for producing ultrafine particles by a conventional electrostatic classification method.

FIG. 4 is a schematic diagram showing the difference in density distribution depending on the particle size of ultrafine particles according to Example 1 of the present invention.

FIG. 5 is a diagram showing collection positions of ultrafine particles in Example 1 of the present invention.

FIG. 6 is an example of particle size distribution of CdTe ultrafine particles produced according to Example 1 of the present invention.

FIG. 7 is an example of the particle size distribution of CdTe ultrafine particles produced according to Example 1 of the present invention.

FIG. 8 is an example of optical absorption characteristics measured by dispersing ultrafine particles produced according to Example 1 of the present invention in glass.

[Explanation of symbols]

1: Vacuum container, 2: Material used as raw material for ultrafine particles, 3: Ultrafine particle shielding object 3A: Opening of ultrafine particle shielding object, 4: Laser light, 4
A: Laser light introduction window 5, 5A, 5B, 5C, 5D: Substrate, 6: Substrate holder, 7: Inert gas introduction pipe 8: Gate valve, 9: Ultrafine particle generation container, 10: Ultrafine particle collection container 11 : Orifice, 12: Conductance variable valve 13: Mass flow controller, 14: Low pressure container, 1
5: Electrode 16: High-voltage DC power supply, 17: Charged ultrafine particles, 1
8: Sheath air 19: Classified ultrafine particles, 20: Excess air, 21: Ultrafine particles, 22: Inert gas 23: Density distribution of small particles, 24: Density distribution of large particles

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shuhei Tanaka 3-5-11 Doshomachi, Chuo-ku, Osaka City Japan Sheet Glass Co. Ltd.

Claims (5)

[Claims] 1. A method for producing ultrafine particles, which comprises forming ultrafine particles by rapidly evaporating a material, which is a raw material for ultrafine particles, in an inert gas by heating and vaporizing the generated vapor to collide with the inert gas, By blocking a part of the movement of the vapor or the ultrafine particles with a shielding object, a space not reached by the vapor or the ultrafine particles traveling straight is formed, and the ultrafine particles are collected in the space. Method for producing ultrafine particles. 2. An ultrafine particle generation container having a heating and evaporation means for a raw material of the ultrafine particles, an ultrafine particle collection container having an ultrafine particle collecting means, and a fine space in which the internal spaces of both containers are integrated. Using an apparatus composed of an ultrafine particle transport tube having holes to rapidly cool the vapor of the raw material of the ultrafine particles heated and vaporized in the ultrafine particle generation container into which the inert gas is introduced, by colliding with the inert gas. To form ultrafine particles, and introduce the ultrafine particles through the ultrafine particle transport pipe into the ultrafine particle collecting container in which the internal pressure of the inert gas is kept lower than that of the ultrafine particle generating container to collect the ultrafine particles. In the manufacturing method,
A method for producing ultrafine particles, characterized in that ultrafine particles are collected in a space in the ultrafine particle collection container that does not reach the ultrafine particles traveling straight from the ultrafine particle transport pipe. 3. The manufacturing method according to claim 1, wherein the heating and evaporating means is a high energy laser for irradiating the material. 4. The method for selecting the particle size of the ultrafine particles to be collected is
The production method according to claim 1 or 2, which is a selection method by changing the type or pressure of the inert gas, the magnitude or direction of the initial velocity of the vapor or ultrafine particles, or the position for collecting the ultrafine particles. . 5. The method according to claim 4, wherein the ultrafine particles to be collected have a particle size of 20 nm or less.