JP2005239960A - Method for producing phosphor fine particle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing phosphor fine particles that can produce more fine, uniform sphere particles, can readily expand the industrial application range and easily permits mass production to further improve the process relating to the prior art and produce phosphor fine particles having more improved properties. <P>SOLUTION: In this method for producing phosphor fine particles, the solution including phosphor raw material is atomized to fine liquid drops and the resultant liquid drops are introduced into flame 3e together with the carrier gas, as the temperature of the flame 3e is controlled by adjusting the flow volume of the fuel gas to form fine particles in the flame and the formed fine particles are heated again. This second heating is preferably carried out in a reductive atmosphere. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing phosphor fine particles, and more particularly to a method for producing phosphor fine particles having excellent characteristics using a flame method.

  At present, many fine particles (particulate materials) used industrially are produced by a solid phase method. The solid phase method is a method in which a mixture of raw material powders is placed in a baking container, heated at a high temperature for a long time to cause a solid phase reaction, and then pulverized with a ball mill or the like. However, since the solid phase method is subjected to a pulverization process, the produced fine particles are irregular in shape and have a poor particle size distribution, and it is difficult to produce uniform fine particles. In particular, in the case of producing fine particles of a material containing multiple components (such as an electronic material) (multicomponent material), there is a problem that impurities are included.

  Therefore, a method for producing fine particles by a spray pyrolysis method has been developed as a fine particle production method that can replace the solid phase method. In the spray pyrolysis method, the raw material solution mixed well at the molecular level is sprayed to form microdroplets, and then these microdroplets are introduced into a pyrolysis synthesis furnace and heated for thermal decomposition synthesis. This is a method for producing chemically uniform fine particles. The spray pyrolysis method has an advantage that the reaction time is as short as a few seconds, fine particles can be continuously produced, and the apparatus such as a pyrolysis synthesis furnace used for this is simple. For this reason, research on the production of functional fine particles by the spray pyrolysis method using an electric furnace as a pyrolysis synthesis furnace (pyrolysis reactor) is being actively conducted.

  The following Patent Document 1 discloses a method for producing a cerium-activated yttrium aluminate phosphor, in which an aqueous solution containing yttrium, cerium, and aluminum is prepared, and the aqueous solution is formed into droplets together with a carrier gas and introduced into a thermal decomposition reactor. Is disclosed.

JP 2000-87033 A

  However, in the conventional method for producing fine particles by the spray pyrolysis method as described above, as shown in Patent Document 1, fine particles having a particle size uniform enough to be used as a phosphor because of poor crystallinity when heated once. It is necessary to heat again in order to produce. For this reason, two stages of manufacturing processes are required, which is complicated and may hinder mass production. Further, in the conventional pyrolysis synthesis furnace, fine particles are generated by heat transfer in the air, so that energy efficiency and productivity are low, and it is difficult to expand the application range industrially.

  In view of such circumstances, the present applicant previously proposed a method for producing phosphor fine particles using a flame method according to Japanese Patent Application No. 2003-358527 “Method for producing fine particles” (hereinafter referred to as the prior application). doing. In this method, a raw material solution containing a phosphor raw material is formed into droplets, the droplet-formed raw material solution is introduced into a flame together with a carrier gas, and the flow rate of the fuel gas is controlled to control the temperature of the flame. Is controlled to produce fine particles in a flame.

  The present invention is a further improvement of this method. The main point is that the phosphor fine particles produced by the flame method having the above-mentioned characteristics have sufficiently practical characteristics. It is the point which discovered that the characteristic as the fluorescent substance can be improved drastically by reheating (additional heating).

  That is, the object of the present invention is to produce spherical and homogeneous fine particles having a smaller particle diameter, and suppress the production cost, expand the industrial application range, and facilitate mass production (scale-up). An object of the present invention is to provide a method for producing phosphor fine particles, which is a further improvement of the “method for producing fine particles” according to the prior application and can produce phosphor fine particles having further improved characteristics.

  In order to solve the above-described problems, a method for producing phosphor fine particles according to the present invention includes forming a raw material solution containing a phosphor raw material into droplets and putting the raw material solution into a flame together with a carrier gas in a flame. The temperature of the flame is controlled by introducing and controlling the flow rate of the fuel gas, fine particles are generated in the flame, and the generated fine particles are reheated.

  In the method for producing phosphor fine particles according to the present invention, it is preferable to control the size of the produced fine particles by controlling the concentration of the raw material solution containing the phosphor raw material. Moreover, it is preferable to make the said raw material solution into droplets using an ultrasonic wave.

  Further, in the method for producing phosphor fine particles according to the present invention, the flame has an equivalent ratio of methane and oxygen as fuel of 0.9 or more of a theoretical value, and the flow rate of methane is within a predetermined range. It is preferable to form in a certain state. Furthermore, the temperature of the flame is preferably controlled in the range of 1700 ° C to 4700 ° C.

In the method for producing phosphor fine particles according to the present invention, the reheating treatment is preferably performed in a reducing atmosphere. Here, as the reducing atmosphere, for example, an atmosphere realized by a mixed gas of 30% hydrogen: 70% argon can be suitably used.
Furthermore, in the method for producing phosphor fine particles according to the present invention, the reheating treatment is preferably performed in a temperature range of 1200 ° C. to 1400 ° C. using, for example, an electric furnace.

  Here, the phosphor raw material is preferably any one selected from the group consisting of barium, magnesium, aluminum, europium, yttrium, europium, yttrium, aluminum, terbium, or gadolinium, and europium.

  According to the method for producing phosphor fine particles according to the present invention having the above-described configuration, it is possible to produce phosphor fine particles having further improved characteristics as a phosphor as compared with the case of the method according to the previous application. There is a remarkable effect of being able to.

  The method for producing phosphor fine particles according to the present invention provides a method for further improving the characteristics of the phosphor fine particles produced by using the flame method by reheating. The method for producing phosphor fine particles according to the present invention (hereinafter also simply referred to as the production method according to the present invention) is a method of heating a phosphor raw material produced by the flame method according to the prior application, and further heating in an electric furnace or the like. In this method, reheating treatment is performed under a predetermined condition using an apparatus.

  Various methods are used for forming droplets of the raw material solution. For example, a method of spraying raw material solution while sucking up the raw material solution with pressurized air, a method of dropping the raw material solution on a rotating disk at a constant speed to form droplets by centrifugal force, a raw material solution surface A method of generating a droplet by applying a high voltage to the substrate, a method of forming a raw material solution into a droplet using ultrasonic waves, and the like are conceivable.

  Sub-micron to micron order particle size used for display phosphors such as cathode ray tubes (CRTs), field emission displays (FEDs), and plasma display panels (PDPs) For producing fine particles (that is, phosphor fine particles, hereinafter simply referred to as fine particles), a method of forming droplets using ultrasonic waves capable of forming droplets having a relatively uniform droplet diameter is preferable. In addition, in this specification, the manufacturing method of microparticles | fine-particles which uses a flame method after making a raw material solution into droplets using such an ultrasonic wave is called an ultrasonic spray flame method.

  In the case of the fine particles as described above, the raw material of the phosphor raw material that is a constituent metal element is an inorganic salt or organic material that is water-soluble and can generate oxides and sulfides when heated to high temperatures. Metal compounds and the like can be used. Moreover, the oxide of the phosphor raw material used as the constituent metal element of such fine particles can be used by dissolving in an acid. In addition, when manufacturing microparticles | fine-particles, it is preferable to use the nitrate of the constituent metal element. This is because the constituent metal elements are ionized in the form of nitrate, so that they are easily decomposed by heating to produce fine particles.

  As the carrier gas, use of air, nitrogen, argon, hydrogen, or the like can be considered, but neutral or reducing gas such as nitrogen, argon, or hydrogen is preferable, and in particular, neutral nitrogen, argon is used. Is preferred.

  As the flame fuel gas, for example, methane and oxygen are used. However, the fuel gas is not limited to these materials, and other fuel gas may be used. By controlling the flow rate of these fuel gases, the flame temperature is controlled in the range of 1700 ° C to 4700 ° C. This is because the temperature range of the heating temperature of the pyrolysis reactor in the conventional spray pyrolysis method is a temperature range of about 600 ° C. to about 1900 ° C. or lower (specifically, It can be heated at a temperature of twice or more. In the examples (experimental examples) described below, fine particles are produced by changing the flame temperature at a temperature around 3700 ° C.

  Together with the carrier gas as described above, the raw material solution that has been made into droplets, that is, droplets, are directly introduced into the flame to produce fine particles in the flame. In such a method for producing phosphor fine particles according to the present invention, the droplets need only be heated once in the flame. In this method, since the fine particles are heated by directly introducing the droplets into the flame, the fine particles can be produced at a high temperature which has not been conventionally obtained, and fine particles having good crystallinity are produced. Because it can.

  In the production method according to the present invention, the concentration of the raw material solution containing the phosphor raw material, that is, the concentration of the phosphor raw material that is a constituent element of the fine particles is changed (controlled). It is possible to control the size (particle size).

  The manufacturing method according to the present invention is the main part of the ultrasonic spray flame method, because the operation temperature (control temperature) of the flame is higher as described above than the spray pyrolysis method using a conventional electric furnace. , The generation amount of fine particles increases, the heat of the flame is used as it is, the production cost is low, and the range that can be used industrially is widened, making mass production (scaling up) easy And so on.

  Specifically, in the production amount of fine particles, in the production method according to the present invention, for example, several hundreds per hour is produced in comparison with the conventional production method in which about several grams of fine particles are produced in one hour. Fine particles of the order of grams can be manufactured, and mass productivity can be greatly improved.

  Further, in the reheating treatment method which is an additional part of the production method according to the present invention, by reheating the fine particles produced by the flame method under special conditions, the fluorescence characteristics of the fine particles (fluorescence emission intensity, hereinafter, This also has a great practical effect in that it can dramatically improve the fluorescence intensity).

  Hereinafter, the best mode for carrying out the manufacturing method according to the present invention will be described with reference to the drawings based on the embodiments.

In the examples (experimental examples) described below, BaMgAl ₁₀ O ₁₇ : Eu fine particles used as blue phosphors in the above-described displays such as CRT, FED, and PDP were manufactured by the manufacturing method according to the present invention. .

〔Example〕
FIG. 1 is a schematic diagram of a production apparatus (experimental apparatus) 1 used in the method for producing fine particles according to an embodiment of the present invention. The manufacturing apparatus 1 according to the present example is generated by using an ultrasonic sprayer 2 that sprays a raw material solution containing a phosphor raw material substance into droplets using ultrasonic waves, and a burner 3 that generates a flame. And an electrostatic collector 4 for collecting fine particles.

The phosphor raw material is a substance that becomes a constituent metal element of the generated fine particles. For example, when producing BaMgAl ₁₀ O ₁₇ : Eu fine particles in which Eu is doped in BaMgAl ₁₀ O ₁₇ called BAM of this embodiment, the phosphor raw material is barium (Ba), magnesium (Mg), aluminum (Al ), And europium (Eu). Therefore, as a raw material solution containing a phosphor raw material, barium nitrate (Ba (NO ₃ ) ₂ ), magnesium nitrate (Mg (NO ₃ ) ₂ .6H ₂ O), aluminum nitrate (Al (NO ₃ )) in ultrapure water. ) ₂ · 9H ₂ O) and europium nitrate (Eu (NO ₃ ) ₃ · 6H ₂ O) were used.

In the case of using the manufacturing method according to the present invention, the present embodiment _BaMgAl 10 _O 17: not limited to Eu microparticles, other particles can be generated. As other fine particles that can be generated, for example, Y ₂ O ₃ : Eu fine particles, Y ₃ Al ₅ O ₁₂ called YAG, Y ₃ Al ₅ O ₁₂ : Tb doped with Tb, and Gd ₂ O ₃ : Eu Etc. When producing Y ₂ O ₃ : Eu fine particles, the phosphor raw material is yttrium (Y) and europium (Eu).

Further, for example, when producing Y ₃ Al ₅ O ₁₂ : Tb fine particles, the phosphor raw material that is a constituent metal element of the fine particles is yttrium (Y), aluminum (Al), and terbium (Tb). _Further, Gd ₂ O 3: When producing the Eu particles, phosphor raw material is a metal element for the fine particles, a gadolinium (Gd) and europium (Eu).

  In this example, barium (Ba), magnesium (Mg), aluminum (Al), and europium (Eu) were used as the phosphor raw material. However, as examples of other phosphor raw materials, yttrium (Y) and europium were used. Other fine particles can be produced using (Eu), yttrium (Y), aluminum (Al), terbium (Tb), gadolinium (Gd), europium (Eu), or the like.

The ultrasonic sprayer 2 sprays this raw material solution using, for example, ultrasonic waves from a piezoelectric crystal to form droplets. A burner 3 is installed above the ultrasonic sprayer 2, and a flame 3 e is generated above the burner 3. The burner 3 is composed of a plurality of cylinders 3a to 3d having a coaxial center. A carrier gas is fed into the ultrasonic sprayer 2 and the burner 3. By feeding the carrier gas, the droplets formed by the ultrasonic sprayer 2 are directly introduced into the flame 3e of the burner 3 through the cylinder 3a of the burner 3. For example, nitrogen (N ₂ ) is used as the carrier gas. A flow meter 9 is attached to the pipe 8 for feeding the carrier gas.

  FIG. 2 shows an enlarged schematic view of the burner 3. The burner 3 is comprised from the some cylinder 3a-3d which has a coaxial center as mentioned above. 2A is a front view of the burner 3 in the direction perpendicular to the coaxial direction, and FIG. 2B is a side view of the burner 3 in the direction parallel to the coaxial direction. The cylinder 3a is located at the most center of the burner 3, and the circumference is surrounded by the cylinder 3b, the cylinder 3c, and the cylinder 3d in order. The length of the cylinder 3a is the longest and protrudes downward. The cylinder 3b, the cylinder 3c, and the cylinder 3d that sequentially surround the outside of the cylinder 3a are configured such that the lengths thereof are sequentially shortened.

In the present embodiment, two pipes 5a and 5b are connected to the burner 3, and fuel gas is fed into the burner 3 through these pipes 5a and 5b. For example, methane (CH ₄ ) and oxygen (O ₂ ) are used as the fuel gas. The flow rates of these fuel gases can be changed by the mass flow controllers 6a and 6b attached to the pipes 5a and 5b, and the fuel gas is controlled. By controlling the fuel gas, the temperature in the flame 3e generated in the burner 3 is controlled. For safety, check valves 7a and 7b are provided in the pipes 5a and 5b through which the fuel gas passes.

In the burner 3, methane (CH ₄ ) is fed into the cylinder 3b surrounding the outer periphery of the cylinder 3a through the pipe 5b. Oxygen (O ₂ ) is fed into the cylinder 3c surrounding the outer periphery of the cylinder 3b through the pipe 5a. In addition, droplets formed by the ultrasonic sprayer 2 are directly introduced into the cylinder 3 a located at the center of the burner 3 together with nitrogen as a carrier gas. In addition, the inside of the cylinder 3d surrounding the outer periphery of the cylinder 3c is provided as a spare.

The electrostatic collector 4 collects the fine particles generated by the reaction in the flame 3e of the burner 3 in the main body 4a using the electrostatic force generated by the high voltage applied by the high voltage generator 4b. The electrostatic collector 4 is heated by a heater (not shown) or the like in order to improve the collection efficiency. In order to suck the NO _x and the like in the carrier gas increases with particles produced in a flame, the pump 4d is provided, the suction gas is collected in a cold trap (cold trap) within 4c The clean gas is discharged via the pump 4d.

  FIG. 3 shows an example of the configuration of an electric furnace 10 used as a reheating device for reheating fine particles collected by the electrostatic collector 4. In this configuration example, Red Devil 14 (trademark) manufactured by Ishikawa Sangyo Co., Ltd. was used as the electric furnace 10 for reheating. This apparatus is capable of high-temperature treatment (2200 ° C. in the case of an argon atmosphere) in various gas atmospheres.

  The electric furnace 10 used in this configuration example is centered on a processing chamber 12b in which a heater 12c for heating is disposed around and on the bottom surface of a main body 12 having a lid 12a, and a desired atmosphere is provided in the processing chamber 12b. A gas introduction pipe 16 and an exhaust pipe 18 are provided for formation. The gas introduction pipe 16 is provided with a mass flow controller 16a for adjusting the gas flow rate, and the exhaust pipe 18 is provided with an exhaust adjustment valve 18a.

  When reheating is performed by the electric furnace 10, the processing target fine particles are placed in, for example, the crucible 14 and placed in the processing chamber 12b, and heating by the heater 12c is started. A predetermined amount of a gas for forming a desired atmosphere is flowed through the tube 18, and the temperature of the processing chamber is controlled to a predetermined temperature by a temperature adjusting means (not shown), and the processing target fine particles are reheated.

  Here, since the reheating treatment temperature described above greatly affects the fluorescence characteristics (fluorescence intensity) of the treated fine particles, it is assumed that the experiment is performed by changing to a plurality of levels (multiple stages), and the atmosphere in the treatment chamber Is a predetermined reducing atmosphere obtained in advance by a prior experiment. In addition, it is practically effective that the gas flow rate for forming this reducing atmosphere is in a range of, for example, about 1 to 10 L / min.

Next, the manufacturing method according to the present embodiment will be described in detail.
First, barium nitrate (Ba (NO ₃ ) ₂ ), magnesium nitrate (Mg (NO ₃ ) ₂ .6H ₂ O), aluminum nitrate (Al (NO ₃ ) ₂ .9H ₂ O), and europium nitrate (Eu ( the _{NO 3) 3 · 6H 2 O} ) a raw material solution obtained by dissolving in ultrapure water was prepared. These raw material solutions were sprayed by the ultrasonic sprayer 2 to form droplets, and introduced directly into the center of the flame 3e through the cylinder 3a of the burner 3 with nitrogen (N ₂ ) as a carrier gas.

  Here, the effect on the fluorescence emission intensity is examined by changing the content of europium (Eu) as an activator into four stages of 8%, 10%, 12%, and 14%. This is because, in the manufacturing method according to the present example, the effect of increasing the content of europium (Eu) over 6%, which is the conventional general content, has an effect on fluorescence characteristics (improvement of fluorescence intensity). This is because is estimated.

Methane (CH ₄ ) and oxygen (O ₂ ) were used as the fuel gas for the flame 3e, and the temperature of the flame 3e was controlled by changing the flow rate of these fuel gases by the mass flow controllers 6a and 6b. . Specifically, by fixing methane (CH ₄ ) at 1.5 L / min, nitrogen (N ₂ ) as a carrier gas at 2.0 L / min, and changing only the flow rate of oxygen (O ₂ ), The temperature of the flame 3e was controlled. Here, L / min represents the flow rate of gas flowing in 1 minute / liter: 1 minute.

Fine particles produced by reaction in the flame of the burner 3 were collected by an electrostatic collector 4 heated to about 200 ° C.
Next, the collected fine particles were reheated using the above-described reheating electric furnace 10. In this reheating treatment, 5 grams of the collected fine particles are put in a crucible 14 and placed in the treatment chamber 12b of the electric furnace 10, and a reducing atmosphere forming gas (mixed gas of 30% hydrogen and 70% argon) is used. The temperature in the furnace was changed in three stages of 1200 ° C., 1300 ° C., and 1400 ° C. while flowing 5 L / min.

  FIG. 4 shows an example of an SEM photograph of fine particles after the reheating treatment in the electric furnace 10. The example shown in FIG. 4 is an example of an SEM photograph of fine particles obtained when reheating is performed at a temperature of 1400 ° C. Although illustration is omitted, no particular noticeable change is observed in the shape, size, etc. of the fine particles due to changing the temperature in the reheating treatment to three stages of 1200 ° C., 1300 ° C., and 1400 ° C.

In FIG. 5, as described above, the change in fluorescence intensity when the content of europium (Eu) as an activator is changed in four stages of 8%, 10%, 12%, and 14% is shown in FIG. Shown in the situation before and after. In addition, the reheating temperature here is 1400 degreeC.
As shown in FIG. 5, when the content rate of europium (Eu) is changed as described above, it appears that there is a maximum value of the fluorescence intensity around the content rate of 10% to 12%.

  In addition, the absolute value of the fluorescence intensity changes greatly before and after reheating. In this example, the absolute value of the fluorescence intensity is increased by about 3.5 times (when the europium (Eu) content is 12%) to about 5 times (when 8%). . However, the tendency of having the maximum value of the fluorescence intensity with respect to the europium (Eu) content is maintained as it is.

Next, from the result of FIG. 5, here, the content rate of europium (Eu) is fixed to 12%, and as described above, the temperature in the reheating treatment is three stages of 1200 ° C., 1300 ° C., and 1400 ° C. Fine particles were produced in place of the above, and the change in fluorescence intensity of the obtained fine particles was measured.
The result was as shown in FIG.

  That is, as shown in FIG. 6, when the europium (Eu) content is 12%, the fluorescence intensity of the fine particles obtained by reheating under the reheating treatment conditions of 1200 ° C., 1300 ° C., and 1400 ° C. is About 70% of the product particles (when the reheating temperature is 1200 ° C.) to about 90% (when the temperature is 1400 ° C.). Here, the product particles are particles that are generally distributed as products.

From the results shown in FIG. 6, it can be seen that the fine particles produced by the production method according to the present invention exhibit fluorescence characteristics (fluorescence intensity) that are very close to those of commercial particles.
As a result, it has been known that phosphor fine particles have a characteristic that the fluorescence intensity increases as the particle diameter increases. However, the fine particles produced by the production method according to the present example Considering that there is only a fraction of the size of product particles, it can be said that a remarkable fluorescence intensity improvement effect was obtained.

  That is, the particle size of the fine particles produced by the production method according to this example is about 1.0 μm, whereas the particle size of the commercial particles is about 5 μm to about 5 μm as shown in the SEM photograph in FIG. Considering the number of fine particles in the layer (film) when the phosphor is used in the form of a layer (film), the fluorescence intensity as the phosphor layer (film) is determined by the manufacturing method according to this example. When the manufactured fine particles are used, there is a possibility that the number of times is improved several times as compared with the case of using commercial particles.

  In summary, in this example, when the content of europium (Eu) is set within a preferable range and a BAM fine particle is manufactured by applying a manufacturing method called flame method plus reheating, a simple substance (individual fine particles) In the mean of, it is possible to obtain fine particles having a fluorescence intensity of about 70% to 90% of conventional product particles, and when this is used as a phosphor layer (film), It can be said that it is possible to obtain a phosphor layer (film) that exhibits a fluorescence intensity several times that of product particles.

  In addition, when the fine particles produced by the production method according to the present embodiment are used in the above-mentioned display such as CRT, FED, PDP, etc., the unevenness at the time of coating and vapor deposition can be reduced because the particle size is small, It is also possible to reduce the thickness of the phosphor layer.

  As mentioned above, although the manufacturing method of the microparticles | fine-particles based on this invention was demonstrated based on one embodiment, this invention is not limited to such embodiment, In the range which does not deviate from the meaning of this invention, it changes suitably. -Needless to say, improvements may be made.

It is a typical schematic diagram of a manufacturing device used for a manufacturing method of particulates concerning an example of the present invention. FIG. 2 is an enlarged schematic view of a burner. It is a typical schematic block diagram of a reheating apparatus. It is an example of the SEM photograph of the reheated microparticles. It is a graph which shows the change of the fluorescence intensity at the time of changing the content rate of europium (Eu). It is a graph which shows the change of the fluorescence intensity at the time of changing reheating temperature. It is an example of the SEM photograph of a common commercial particle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Manufacturing apparatus 2 Ultrasonic atomizer 3 Burner 3a, 3b, 3c, 3d Cylinder 3e Flame 4 Electrostatic collector 4a Main body 4b High voltage generator 4c Cooling trap 4d Pump 5a, 5b, 8 Piping 6a, 6b Mass flow controller 7a, 7b Check valve 8 Carrier gas inlet piping 9 Flow meter 10 Reheating device 12 Main body 12a Lid 12b Processing chamber 12c Heater 14 Crucible 16 Gas introduction pipe 16a Mass flow controller 18 Exhaust pipe 18a Exhaust adjustment valve

Claims (8)

The raw material solution containing the phosphor raw material is made into droplets,
The raw material solution that has been made into droplets together with a carrier gas is introduced into the flame,
Controlling the temperature of the flame by controlling the flow rate of the fuel gas to produce fine particles in the flame,
A method for producing phosphor fine particles, wherein the produced fine particles are reheated.   2. The method for producing phosphor fine particles according to claim 1, wherein the size of the fine particles produced is controlled by controlling the concentration of the raw material solution containing the phosphor raw material.   The method for producing phosphor fine particles according to claim 1 or 2, wherein the raw material solution is formed into droplets using ultrasonic waves.   4. The flame according to claim 1, wherein an equivalent ratio of methane and oxygen as fuel is 0.9 or more of a theoretical value, and a flow rate of methane is within a predetermined range. A method for producing the phosphor fine particles according to Item.   The method for producing phosphor fine particles according to any one of claims 1 to 4, wherein the temperature of the flame is controlled in a range of 1700 ° C to 4700 ° C.   The method for producing phosphor fine particles according to claim 1, wherein the reheating treatment is performed in a reducing atmosphere.   The method for producing phosphor fine particles according to claim 6, wherein the reheating treatment is performed in a temperature range of 1200 ° C to 1400 ° C.   2. The phosphor raw material is any one selected from the group consisting of barium, magnesium, aluminum, europium, yttrium, europium, yttrium, aluminum, terbium, or gadolinium, and europium. 8. The method for producing phosphor fine particles according to any one of 7 to 7.

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