KR100656242B1 - Manufacturing method of spherical phosphor powder of compact structure - Google Patents

Abstract

The present invention relates to a method for producing a spherical phosphor powder having a compact structure, and more particularly, in the production of phosphor powder by spray pyrolysis, a certain amount of a specific hydrophilic organic compound in a spray solution for spray pyrolysis as a drying regulator. When the spray pyrolysis process is added, the resulting phosphor powder particles have a spherical shape and at the same time, the surface area decreases due to an increase in the internal density, and exhibits excellent luminescence properties, resulting in high brightness of the next-generation plasma flat panel display, which is easy to thin and light. It relates to a method for producing a spherical phosphor powder of a compact structure that can be usefully used as a phosphor for improving the performance of illumination.

Drying regulator, compact structure, spherical phosphor powder

Description

Preparation Method of Spherical Phosphor Powder of Compact Structure {Preparation method of Spherical and Dense Phosphor Powders}             

1 is a photograph showing a Y ₂ O ₃ : Eu phosphor powder prepared in Example 4 according to the present invention with a scanning electron microscope.

2 is a photograph showing the surface of the Y ₂ O ₃ : Eu phosphor powder particles prepared in Example 4 according to the present invention with a scanning electron microscope.

Figure 3 is a photograph showing the surface of the Y ₂ O ₃ : Eu phosphor powder particles prepared in Example 5 according to the present invention with a scanning electron microscope.

Figure 4 is a photograph showing the Y ₂ O ₃ : Eu phosphor powder particles prepared in Comparative Example 1 by a scanning electron microscope.

5 is a photograph showing the Y ₂ O ₃ : Eu phosphor powder particles prepared in Comparative Example 5 with a scanning electron microscope.

6 is a photograph showing the surface of the Y ₂ O ₃ : Eu phosphor powder particles prepared in Comparative Example 5 with a scanning electron microscope.

Figure 7 shows the surface area change of the phosphor powders prepared in Examples 4 to 6 according to the present invention.

8 shows surface area changes of phosphor powders prepared in Comparative Examples 1 to 5. FIG.

9 shows emission spectra of the phosphor powders prepared in Examples 4 to 6 and Comparative Example 5 according to the present invention.

The present invention relates to a method for producing a spherical phosphor powder having a compact structure, and more particularly, in the production of phosphor powder by spray pyrolysis, a certain amount of a specific hydrophilic organic compound in a spray solution for spray pyrolysis as a drying regulator. When the spray pyrolysis process is added, the resulting phosphor powder particles have a spherical shape and at the same time, the surface area decreases due to an increase in the internal density, and exhibits excellent luminescence properties, resulting in high brightness of the next-generation plasma flat panel display, which is easy to thin and light. It relates to a method for producing a spherical phosphor powder of a compact structure that can be usefully used as a phosphor for improving the performance of illumination.

Phosphors are materials that emit light in the visible region that can be seen by the human eye by receiving high energy in the form of light or electronics from the outside, and these phosphors are key materials that determine the quality of lamps or display products. In particular, in order for plasma displays and field emission displays to realize natural colors, excellent phosphors are necessary. The development of such display technology requires improvement of the photochemical properties of the phosphor as well as powder properties such as shape and size. That is, as flat panel displays gradually become high quality and fine, a phosphor having a spherical shape with a fine size is required, and efforts have been made to synthesize such phosphors and improve light emission characteristics.

On the other hand, one of the most typical vapor phase synthesis method for producing the spherical phosphor powder is spray pyrolysis.

In the spray pyrolysis process, the shape and luminescence properties of the phosphor powder vary according to the characteristics of the precursor solution. In general, a phosphor powder prepared from a solution in which a nitrate or chloride precursor is dissolved in water is prepared with a hollow structure, and a colloidal solution [Korea Patent Publication No. 2001-0002822] is prepared to improve the porous shape. It can be used as or by adding citric acid and ethylene glycol [Korean Patent Publication No. 2002-0075058] to modify the precursor solution to obtain a spherical powder filled inside. These methods enable the production of phosphor powders having a spherical shape in the filled structure, but retain much of the porous property and are not made of a dense structure powder. This is because the powder formed from the colloid is composed of secondary particles formed from the primary particles, respectively, causing voids between the primary particles, and when the organic addition method is used, a powder containing a large amount of carbon components is produced and the carbon The components undergo post heat treatment to generate voids.

The microporosity thus formed can be reduced later by increasing the temperature of the heat treatment. However, the excessive heat treatment temperature causes the spherical shape to be lost or the powders are severely aggregated to deteriorate their properties. Accordingly, in the case of the aluminate-based phosphor, Korean Patent Registration No. 10-0411176 discloses that the aluminate-based phosphor manufactured by spray pyrolysis using an inorganic polymer solution has a spherical shape with high density of particles and high thermal stability. It is known that not only has agglomeration between powder particles, but also mass production.

Without being limited to this, if the density of the phosphor powder can be further improved, the luminous efficiency can be further improved. In other words, when the phosphor particle size is fixed, the smaller the surface area is, the more favorable the light emission characteristics, since the main factor causing the non-luminescent consumption of the electrons excited from the external excitation source is the internal defect or the surface defect. Therefore, since a small surface area means a small surface defect, it is possible to increase the luminous efficiency by reducing the non-luminous consumption rate of the excitation electrons.

In general, the phosphor powder prepared by the spray pyrolysis process tends to have a porous powder form rather than a dense structure because the droplets of the precursor solution droplets are rapidly dried and pyrolyzed in a high temperature reactor. As a result, the emission luminance of the phosphor is lowered.

Therefore, there is an urgent need for a method for producing a phosphor having excellent luminous intensity by improving the density in manufacturing a spherical phosphor powder having a structure filled by a spray pyrolysis process.

Accordingly, the present inventors have tried to improve the density of the phosphor powder prepared by the spray pyrolysis process as described above. As a result, the spray solution used in the conventional spray pyrolysis process is carried out by adding a hydrophilic organic compound having affinity for water while maintaining a specific vapor pressure and boiling point range in order to prevent the droplets from drying or pyrolyzing rapidly. As a result, it was found that the surface area was significantly reduced by increasing the density while having a spherical shape, thereby completing the present invention.

Accordingly, an object of the present invention is to provide a method for producing spherical phosphor powder having excellent luminescence intensity because the density is greatly improved by using a specific hydrophilic organic compound as a drying regulator during spray pyrolysis.

The present invention provides a method for producing phosphor powder by spray pyrolysis, wherein the spray solution for spray pyrolysis is a hydrophilic organic compound having a vapor pressure of 0.05 to 25 mmHg (room temperature) and a boiling point of 110 to 250 ° C. as a drying regulator. There is a feature in the method for producing the phosphor powder prepared by adding at a concentration of -2.0 M.

Hereinafter, the present invention will be described in detail.

In the spray pyrolysis process, a specific hydrophilic organic compound is added to the precursor solution as a drying control agent, thereby preventing droplets of the dropletized precursor solution from being rapidly dried or pyrolyzed in a high temperature reactor, thereby making the structure compact. The present invention relates to a method for producing a spherical phosphor powder having improved lightness and thereby excellent light emission intensity and relatively low light emission luminance.

The spray pyrolysis process according to the present invention is a method for producing ordinary spherical phosphor powder particles, which is not particularly limited, and the vapor pressure is 0.05 to 25 mmHg at room temperature, and the boiling point is 110 to 250 ° C. in the precursor solution for producing the phosphor powder. Phosphorus hydrophilic organic compound is added as a drying regulator to prepare a spray solution. The organic compound is not used as a drying regulator because it contains a certain amount in the art, and they are generally used as a solvent using a large amount, or for the purpose of washing, a relatively small amount in the concept of additives as in the present invention This is different from that used for the purpose of drying control.

If the vapor pressure is less than 0.05 mmHg or the boiling point is higher than 250 ℃ at room temperature of the organic compound, the affinity with water or high viscosity cannot be used, and if the vapor pressure is higher than 25 mmHg or boiling point is less than 100 ℃ Since the problem of volatilization occurs earlier, it is preferable to use an organic compound having the above-mentioned range. Such drying regulators are particularly desirable to be readily soluble in water, for example N, N-dimethylformamide (DMF), formamide, glycerol and the like. They have specific boiling points and vapor pressures as described above, and at the same time, are easily dissolved in water, and thus are effective in the production of phosphor powders according to the present invention. That is, the present invention is characterized by the technical constitution of the addition and use of the spray solution of the spray pyrolysis process by selectively using an organic compound which has a specific boiling point and vapor pressure and can be easily dissolved in water.

Such a drying regulator is preferably added in a concentration range of 0.05 to 2.0 M, preferably 0.1 to 2.0 M. When the amount of the drying regulator is less than 0.05 M, the amount is too small to achieve the purpose of expressing the densification effect, and when it exceeds 2.0 M, it becomes difficult to droplet the solution.

Since it is difficult to form spherical shapes or densities only with the above-mentioned drying regulators, it is not used in all methods of producing phosphors, but a solution preparation method capable of making a filled structure, that is, processes such as spray pyrolysis as in the present invention and It is preferable to use in combination.

In addition, it can be used in combination with a process for preparing a spherical phosphor powder filled in the prior art, for example, a method for producing a phosphor powder filled inside by using a colloidal solution of Korea Patent Registration No. 10-0323404, A method for preparing a phosphor powder having a structure filled with an inorganic polymer solution of Korean Patent No. 10-0411176, or an organic additive of citric acid and ethylene glycol of Korean Patent No. 10-0419859 in a proper ratio By adding a specific drying regulator to the method for producing the phosphor, it is possible to use a phosphor powder having a more compact structure.

The production method according to the present invention may be further applied to conventional phosphor powders, but is not particularly limited, and specifically, for example, Y ₂ O ₃ : Eu, Gd ₂ O ₃ : Eu, (Y, Gd) ₂ O ₃ : Eu, Zn ₂ SiO ₄ : Mn, CaMgSi ₂ O ₆ : Eu, Y ₂ SiO ₄ : (Tb or Ce), Y ₂ Al ₅ O ₁₂ : (Eu, Tb, or Ce), BaMgAl ₁₀ O ₁₇ :( Eu or Mn), BaMgAl ₁₄ O ₂₃ : (Eu or Mn), MAl ₂ O ₄ : Eu (M = Ba, Sr, Ca) and the like can be prepared.

As described above, the phosphor powder prepared according to the present invention has excellent light emission characteristics while being compact and having a small surface area in the range of 1 to 7 m 2 / g.

Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by these Examples.

 Example 1

1 L of a precursor solution was prepared using a solution in which yttrium nitrate was dissolved in nitric acid in distilled water and a solution in which eu nitrate was dissolved in nitric acid. At this time, the concentration of the yttrium solution was 0.5M, the Eu activator concentration was 12.5% based on the yttrium (Y). To the precursor solution prepared above, DMF was added as 1.0 M as a drying regulator to prepare a spray solution. The spray solution prepared above was prepared by using a spray pyrolysis process, followed by heat treatment at 1150 ° C. for 3 hours to prepare a phosphor powder.

Examples 2-4

The same procedure as in Example 1 was carried out, but the powder was prepared by spray pyrolysis using citric acid and ethylene glycol as an organic additive to the spray solution, and then heat-treated at 1150 ° C. for 3 hours. To prepare a phosphor powder. At this time, the citric acid (citric acid) and ethylene glycol (ethylene glycol) was used in the same molar ratio, the concentration of 0.1 M (Example 2), 0.15 M (Example 3) and 0.2 M (Example 4), respectively The reaction was performed while changing.

Examples 5-6

In the same manner as in Example 1, the molar concentration of the organic additives citric acid (citric acid) and ethylene glycol (ethylene glycol) is fixed to 0.2 M, spray pyrolysis process while changing the molar concentration of the DMF drying control agent After the powder was prepared to perform a heat treatment for 3 hours at 1150 ℃ to prepare a phosphor powder. At this time, the drying regulator DMF was changed to 0.25 M (Example 5), 0.75 M (Example 6), respectively.

Examples 7-8

In the same manner as in Example 1, but by adding a different type of the drying regulator, by performing a spray pyrolysis process to prepare a powder, and then heat-treated at 1150 ℃ for 3 hours to prepare a phosphor powder. At this time, formamide (Example 7) and glycerol (Example 8) were used as drying regulators.

Comparative Example 1

In the same manner as in Example 1, the powder was prepared by performing a spray pyrolysis process without using the drying regulator, followed by heat treatment at 1150 ℃ for 3 hours to prepare a phosphor powder.

Comparative Examples 2 to 5

In the same manner as in Example 1, except the drying control agent, using a citric acid (citric acid) and ethylene glycol (ethylene glycol) as an organic additive to perform a spray pyrolysis process to prepare a powder, at 1150 ℃ The phosphor powder was prepared by heat treatment for 3 hours. At this time, the citric acid (citric acid) and ethylene glycol (ethylene glycol) was used in the same molar concentration ratio, respectively, the concentration of 0.05 M (Comparative Example 2), 0.1 M (Comparative Example 3), 0.15 M (Comparative Example 4) And the reaction was carried out while changing to 0.2 M (Comparative Example 5).

The components and contents of the above Examples 1 to 6 and Comparative Examples 1 to 5 are briefly shown in the following table.

division Precursor solution Drying regulator (m) Organic additives Relative brightness (%) matrix Active agent Citric Acid (M) Ethylene Glycol (M) Yttrium Nitrate (M) Eu nitrate (%) ¹⁾ Example One 0.5 12.5 DMF, 1.0 0.0 0.0 101 2 0.5 12.5 DMF, 1.0 0.1 0.1 129 3 0.5 12.5 DMF, 1.0 0.15 0.15 167 4 0.5 12.5 DMF, 1.0 0.2 0.2 208 5 0.5 12.5 DMF, 0.25 0.2 0.2 121 6 0.5 12.5 DMF, 0.75 0.2 0.2 150 7 0.5 12.5 Formamide, 1.0 0.2 0.2 143 8 0.5 12.5 Glycerol, 1.0 0.2 0.2 130 Comparative example One 0.5 12.5 - - - 100 2 0.5 12.5 - 0.05 0.05 68 3 0.5 12.5 - 0.1 0.1 52 4 0.5 12.5 - 0.15 0.15 68 5 0.5 12.5 - 0.2 0.2 93 1): The concentration of Eu nitrate represents the% concentration relative to yttrium (Y).

As described in Table 1, Examples 1 to 8 prepared the phosphor powder using the drying regulator as a main component in the precursor solution, and Comparative Examples 1 to 5 prepared the phosphor powder by excluding the drying regulator.

The phosphor powders of Examples 1 to 8 prepared by adding the drying regulator according to the present invention have a high density while maintaining a perfect spherical shape compared to the phosphor powders prepared in Comparative Examples 1 to 5, thereby greatly improving the luminescence properties. It could be confirmed. The luminescence property was confirmed by the result of measuring the relative intensity of the luminescence spectrum obtained by exciting with ultraviolet light of 254 nm wavelength using a fluorescence spectrophotometer having an Xe lamp.

1 and 2 are Example 4, FIG. 3 is Example 5, FIG. 4 is Comparative Example 1 and FIG. 5 is an electron scanning micrograph of the phosphor powder prepared in Comparative Example 5. You can see that it has a structure. Particularly, Figure 4 shows the hollowness and porosity by excluding the drying regulator and the organic additives, and when only the organic additive is used as shown in Figure 5, the shape of the powder, spherical shape is maintained, but it is more clearly shown in Figure 6 that it is a porous powder. Giving.

On the other hand, Figure 7 is a change in the surface area of Examples 4 to 6 according to the change in the concentration of the drying regulator, Figure 8 shows a change in the surface area of Comparative Examples 1 to 5 according to the change in the concentration of the organic additives. That is, although the surface area is drastically decreased as the concentration of the drying regulator is increased, it can be seen that the decrease in the surface area due to the change in the concentration of the organic additive does not occur.

In addition, Figure 9 shows the relative emission intensity of the phosphor powder prepared in Examples 4 to 6 and Comparative Example 5, it can be seen that greatly improved with the use of the drying regulator.

As described above, the spray pyrolysis process using a certain amount of a specific drying regulator according to the present invention, the spherical, compact structure has a dramatically reduced surface area, so that the luminous intensity is significantly improved, thinning and light weight easy generation It can be usefully used as a phosphor for increasing the brightness of plasma flat panel display and improving the performance of lighting.

Claims (4)

In the method for producing a phosphor powder by spray pyrolysis process, Phosphor powder, characterized in that the precursor solution for spray pyrolysis is prepared by adding a hydrophilic organic compound having a vapor pressure of 0.05 to 25 mmHg (room temperature) and a boiling point of 110 to 250 ° C. at a concentration of 0.05 to 2.0 M as a drying regulator. Manufacturing method. The method of claim 1, wherein the drying regulator is selected from N, N-dimethylformamide (DMF), formamide and glycerol. The method for producing a phosphor powder according to claim 1, wherein the phosphor powder has a surface area of 1 to 7 m 2 / g. The method for producing a phosphor powder according to claim 1, wherein 0.05 to 0.3 M of an organic additive of citric acid or ethylene glycol is further used as the precursor solution.

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