KR100280369B1 - Manufacturing method of green light emitting phosphor - Google Patents

Abstract

The present invention relates to a method for producing a green light emitting phosphor, and more particularly, a base is added to a solution containing a gallium component, and heat-treated by hydrolysis, and then dispersed in a solution containing zinc and manganese components. Oxylic acid was added to precipitate zinc and manganese with oxalate to prepare ZnGa ₂ O ₄ : Mn green luminescent phosphor by wet precipitation method of drying and heat-treating the mixed precipitate. It is a columnar type and has no cohesiveness in powder, and its uniform distribution of manganese, which is an activator, has a very good luminous intensity compared to the conventional manufacturing method, making it suitable for use in electronic display tubes as a low voltage phosphor, and can be widely used in the display industry. So that the green light-emitting phosphor is excited by an electron beam and exhibits an emission spectrum in the visible region. Peaceful relates to a method of manufacturing the same.

Description

Manufacturing method of green light emitting phosphor

The present invention relates to a method for producing a green light emitting phosphor, and more particularly, a base is added to a solution containing a gallium component, and heat-treated by hydrolysis, and then dispersed in a solution containing zinc and manganese components. Oxylic acid was added to precipitate zinc and manganese with oxalate to prepare ZnGa ₂ O ₄ : Mn green luminescent phosphor by wet precipitation method of drying and heat-treating the mixed precipitate. It is a columnar type and has no cohesiveness in powder, and its uniform distribution of manganese, which is an activator, has a very good luminous intensity compared to the conventional manufacturing method, making it suitable for use in electronic display tubes as a low voltage phosphor, and can be widely used in the display industry. So that the green light-emitting phosphor is excited by an electron beam and exhibits an emission spectrum in the visible region. Peaceful relates to a method of manufacturing the same.

Much research has been conducted on phosphors for electronic display tubes, which are used as core materials for color in the display industry. Among them, fluorescence characteristics have been studied for ZnGa ₂ O ₄ : Mn phosphors driven at low voltages using ZnGa ₂ O ₄ having a spinel structure as a matrix and manganese as an activator.

In general, it is known that the luminescence properties of the phosphors are largely dependent on the particle size and crystal structure, so that new matrix materials or methods for manufacturing the phosphors have been developed to improve the luminescence properties of the phosphors. In order to prepare a ZnGa ₂ O ₄ : Mn phosphor, a phosphor was prepared in a powder form by introducing a solid-phase reaction method in which raw materials were mixed and heat-treated. However, since the high temperature is applied to the final calcination process, the phosphor particles are used. Because of the coagulation, the surface of the phosphor is damaged during the grinding process such as grinding, grinding or ball milling, which is necessarily included in the manufacturing process of the phosphor, resulting in the formation of a dead layer on the surface of the phosphor or the incorporation of impurities, resulting in loss of luminescence intensity. There is a problem that comes. In addition, the volatilization of ZnO and Ga ₂ O ₃ due to the high vapor pressure causes serious problems in many cases as the high calcination temperature is applied in the preparation of ZnGa ₂ O ₄ : Mn phosphors by the solid-phase reaction method. In order to reduce the need for a ZnGa ₂ O ₄ : Mn phosphor manufacturing method at a low temperature. For this reason, there is an urgent need for other manufacturing methods that can replace the solid state reaction method.

On the other hand, in order to manufacture high-efficiency phosphors, particle size, particle shape, and even distribution of the active agent in the matrix should be controlled. Therefore, there is an urgent need for a new production method capable of producing phosphor powder having uniform particles and good crystallinity.

The present inventors have found that ZnGa ₂ O _4: Here improve the luminescence properties of Mn phosphor and a result of extensive studies, ZnGa ₂ O ₄ by a wet precipitation method: When manufacturing the Mn phosphor while being phosphor is formed at a low temperature rather than the emission intensity greatly The present invention has been completed by knowing that an excellent green light emitting phosphor can be obtained.

Therefore, the present invention uses the wet precipitation method for the production of ZnGa ₂ O ₄ : Mn phosphor, the phosphor is formed at a lower temperature than the conventional method, the powder particles are coherent in a constant columnar shape, and the luminous intensity is due to the uniform distribution of the active agent. It is an object of the present invention to provide a method for producing a green light emitting phosphor which is excellent.

1 is an X-ray diffraction diagram of a ZnGa ₂ O ₄ : 0.005Mn phosphor prepared in Example 1 according to the present invention,

2 is a photograph of a powder particle of ZnGa ₂ O ₄ : 0.005Mn phosphor prepared in Example 1 according to the present invention with a scanning electron microscope,

Figure 3 is a graph showing the emission intensity according to the concentration of manganese active agent in the ZnGa ₂ O ₄ : Mn phosphor according to the present invention and the phosphor prepared by a conventional solid-phase reaction method,

Figure 4 shows the emission spectrum of the ZnGa ₂ O ₄ : 0.005Mn phosphor prepared in Example 1 according to the present invention.

The present invention provides a method for producing a ZnGa ₂ O ₄ : Mn green light-emitting phosphor, in which a base is added to a solution containing a gallium component to precipitate with a hydroxide, and the solution is heat-treated to convert to a GaO (OH) precipitate. A method for producing a green light-emitting phosphor, in which a precipitate is dispersed in an aqueous zinc compound solution containing a manganese component, and the mixed precipitate obtained by adding oxalic acid and a base is filtered, dried, and calcined.

The present invention will be described in more detail as follows.

In the method for preparing a green light emitting phosphor according to the present invention, as a wet precipitation method, a base is added to a solution containing a gallium component, precipitated with hydroxide, heat treated to hydrolyze, converted to GaO (OH), and then filtered to deposit this precipitate. ZnGa ₂ O ₄ : dispersed in a solution containing zinc and manganese, oxalic acid solution is added thereto, and the hydrogen ion concentration is adjusted with a base to precipitate zinc and manganese with oxalate, filtered and dried and heat treated in air and a reducing atmosphere. It is a method of manufacturing Mn phosphor.

The ZnGa ₂ O ₄ : Mn phosphor prepared by the manufacturing method according to the present invention as described above is formed in a single phase from a low temperature of 700 ° C. and has a uniform columnar shape in which powder particles are not aggregated and are excited by electron beams. Very good green light emission intensity in the region.

In order to synthesize the phosphor according to the present invention, a gallium compound, a zinc compound and a manganese compound may be prepared according to the above-described method.

In the production method according to the present invention, a base is first added to a solution containing a gallium component to precipitate as a hydroxide. As the gallium compound for preparing the solution containing the gallium component, for example, an aqueous solution of gallium nitrate, gallium sulfate or gallium chloride and one or more selected from metal gallium dissolved in nitric acid or hydrochloric acid may be used. In the solution containing the gallium component, it is preferable that the gallium component has a concentration of 0.01 to 5 M in a mixing ratio according to the composition of ZnGa ₂ O ₄ : Mn. If the concentration of the gallium component is less than 0.01M, the amount of water and energy used is excessive and uneconomical. If it exceeds 5M, there is a process problem in that stirring and filtration of the resulting precipitation solution becomes difficult.

At this time, in order to completely precipitate the gallium component, the hydrogen ion concentration of the solution is preferably 5 or more, but preferably adjusted to 6-9. The base added to precipitate the gallium component may be any base capable of precipitating the gallium component such as ammonia water, sodium hydroxide and organic amines. The gallium hydroxide precipitated here is heated and hydrolyzed at a temperature of 80 to 110 ° C. for 30 minutes to 4 hours while stirring in a solution state, and then filtered to obtain a GaO (OH) precipitate. The GaO (OH) precipitate thus obtained is dispersed in an aqueous zinc compound solution containing the manganese component.

The zinc compound solution containing manganese components used in this process is a mixture of zinc compound solution and manganese compound solution. Zinc compounds include, for example, zinc acetate, zinc chloride, zinc nitrate or zinc sulfate, or metal zinc or zinc oxide. And at least one selected from those dissolved in nitric acid, hydrochloric acid, sulfuric acid, etc. may be used, and as the manganese compound, at least one selected from water-soluble manganese acetate, manganese chloride, manganese nitrate, and manganese sulfate may be used. At this time, the zinc component of the zinc compound aqueous solution containing the manganese component according to the composition preferably has a concentration of 0.01 to 5M, preferably to a concentration of 0.1 to 3M. The concentration of manganese used here as an activator for the parent is preferably in the range of 0.01 to 3 mol%. If the concentration of manganese is less than 0.01 mol% or more than 3 mol%, there is a problem that the emission intensity is weak.

In order to precipitate zinc and manganese in an aqueous zinc compound solution containing a manganese component in which the GaO (OH) precipitate is dispersed, an oxalic acid solution is added and a base is added to give a hydrogen ion concentration of 6-10, preferably 7-9. By adjusting between the precipitates are precipitated without loss of zinc and manganese components. At this time, the oxalic acid to be used is suitable in an amount ratio of 100 to 110% with respect to the zinc component contained in the solution, and the oxalic acid solution is dissolved in oxalic acid in water or alcohol to a concentration of about 1 M, and the base prevents the loss of the zinc component. For this purpose, one or more selected from organic amines such as diethylamine, diethanolamine and triethylamine can be used.

Next, the mixed precipitate of gallium, zinc, and manganese prepared above was filtered and dried, and the dried product was filled in a heat-resistant container of the crucible and calcined in air at 700 to 1,300 ° C. for 1 to 10 hours, and the active manganese component. ZnGa ₂ O ₄ : Mn phosphor powder can be obtained by re-firing at 700 to 1,200 ° C. for 1 hour using a hydrogen / nitrogen or carbon monoxide / carbon dioxide mixed gas in order to reduce the temperature.

As described above, the method for producing a ZnGa ₂ O ₄ : Mn phosphor according to the present invention is different from the conventional method, in which a phosphor is prepared in a single phase from a low temperature of 700 ° C., and has no agglomerated columnar powder particles, and uniformity of the active agent. It exhibits excellent green luminescence intensity by one distribution and is very suitable for an electronic display tube as a low voltage phosphor, and is characterized by being excited by an electron beam so as to be widely used in the display industry and displaying an emission spectrum in the visible region.

X-ray diffraction analysis of ZnGa ₂ O ₄ : Mn phosphor powders heat-treated at 800 ° C. in air and reducing atmosphere in the final firing step according to the preparation method of the present invention, obtained as a single phase as shown in FIG. Reaction method [J. Electrochem. Soc., 141, 1950 (1994)] can be confirmed that the phosphor is formed at a temperature lower than 1,100 ℃.

In addition, ZnGa ₂ O ₄ : Mn phosphor powder prepared according to the method of the present invention was observed by scanning electron microscopy (SEM), as shown in Figure 2, the phosphor particles according to the present invention is not agglomerated and constant columnar You can see that you are doing a brother.

On the other hand, ZnGa ₂ O ₄ : Mn phosphor according to the present invention was excited with an electron beam of 254nm to compare the concentration of manganese and the emission intensity of the phosphor in the phosphor prepared by the conventional solid-phase reaction method, shown in Figure 3 As shown in FIG. 2, the maximum emission intensity is shown when the concentration of manganese is 0.5 mol% in both manufacturing methods. However, the phosphor according to the present invention exhibits better green emission intensity in the entire concentration range of manganese. In the case of the method, it is determined that manganese, which is an active agent, is uniformly distributed in the mother.

As described above, as a result of confirming the presence or absence of green light emission of the ZnGa ₂ O ₄ : Mn phosphor according to the manufacturing method of the present invention, as shown in FIG. 4, a green light emission spectrum peculiar to manganese ions having a light emission center at a wavelength of 505 nm was obtained. It was confirmed to show.

Although this invention is demonstrated in detail based on an Example, this invention is not limited to an Example.

Example 1

Aqueous ammonia was added to 200 ml of a 1 M gallium nitrate solution to adjust the hydrogen ion concentration of the solution to 8 to precipitate as gallium hydroxide. The precipitate was converted to GaO (OH) precipitation by hydrolysis at 90 ° C. for 2 hours with stirring in solution. The precipitate was filtered, 100 ml of an aqueous 0.995 M oxalic acid solution containing 0.0005 mol of manganese nitrate was added thereto, and slowly added with diethylamine while stirring to adjust the hydrogen ion concentration of the solution to 8.8. A mixed precipitate of zinc and manganese was obtained. The mixed precipitate was dried at 80 ° C. for 4 hours, then placed in an alumina crucible and calcined at 800 ° C. for 4 hours in air, and then the resulting fired product was heated at 800 ° C. in a reducing atmosphere of 5% hydrogen / nitrogen mixed gas. It was calcined again for 1 hour to obtain the desired phosphor powder.

The composition of the phosphor thus obtained was ZnGa ₂ O ₄ : 0.005 Mn, and exhibited a green emission spectrum having an emission center at 505 nm as shown in FIG. 4 under electron beam excitation of 254 nm.

Examples 2-5

A phosphor powder was prepared in the same manner as in Example 1 except that the composition of the phosphor was carried out as shown in Table 1 below. The luminous intensity according to the composition of the phosphor thus obtained is shown in Table 1 below.

division Composition of phosphor Luminous intensity (arbitrary value) Example 1 ZnGa ₂ O ₄ : 0.005Mn 1,180 Example 2 ZnGa ₂ O ₄ : 0.0001Mn 125 Example 3 ZnGa ₂ O ₄ : 0.001Mn 280 Example 4 ZnGa ₂ O ₄ : 0.01Mn 420 Example 5 ZnGa ₂ O ₄ : 0.03Mn 95

Comparative Example 1

ZnO 4.980 g

Ga ₂ O ₃ 11.529 g

MnCO ₃ 0.035 g

The high purity raw materials were wet-mixed in 20 ml of ethanol and evaporated to dryness, and then placed in an alumina crucible, calcined at 1,100 ° C. for 4 hours in an air atmosphere, and again at 900 ° C. in a reducing atmosphere of 5% hydrogen / nitrogen mixed gas. It was refired for 1 hour at temperature. The final fired product was ground to prepare a phosphor powder.

The composition of the prepared phosphor was ZnGa ₂ O ₄ : 0.005Mn, and showed a green emission spectrum having an emission center at 505 nm under electron beam excitation of 254 nm.

The luminous intensity according to the composition of the phosphor thus obtained is shown in Table 2 below.

Comparative Examples 2 to 5

In the same manner as in Comparative Example 1, the composition of the phosphor was carried out as shown in Table 2 to prepare a phosphor powder. In addition, the luminous intensity according to the composition of the phosphor thus obtained is shown in Table 2 below.

division Composition of phosphor Luminous intensity (arbitrary value) Comparative Example 1 ZnGa ₂ O ₄ : 0.005Mn 315 Comparative Example 2 ZnGa ₂ O ₄ : 0.0001Mn 45 Comparative Example 3 ZnGa ₂ O ₄ : 0.001Mn 75 Comparative Example 4 ZnGa ₂ O ₄ : 0.01Mn 25 Comparative Example 5 ZnGa ₂ O ₄ : 0.03Mn 10

From the comparative results of Examples 1 to 5 and Comparative Examples 1 to 5, the phosphor according to the manufacturing method of the present invention has a very excellent luminous intensity compared to the phosphor prepared according to the conventional method, and particularly ZnGa exhibiting the maximum luminous intensity. _{In the} composition of ₂ O ₄ : 0.005Mn, green emission intensity of about 4 times can be seen.

As described above, the new method for producing a ZnGa ₂ O ₄ : Mn phosphor according to the present invention, unlike the conventional manufacturing method by producing a phosphor at a low temperature, by suppressing the volatilization of zinc and gallium components, the reproducible physical properties of the phosphor It can be expected to have excellent effect in terms of environmental pollution prevention. Especially, it has a uniform columnar shape without agglomeration and has excellent luminous intensity compared to the conventional method, and is very suitable for electronic display tubes as a low voltage driving phosphor. There is a useful effect that can be widely used in the display industry.

Claims (4)

In the method for producing a ZnGa ₂ O ₄ : Mn green light emitting phosphor, A solution containing gallium is selected from ammonia water, sodium hydroxide and organic amines, and a base is added to precipitate the gallium component, which is precipitated with hydroxide. The solution is heat-treated at a temperature of 80-110 ° C. to convert into a GaO (OH) precipitate. And then dispersing the precipitate in an aqueous zinc compound solution containing a manganese component, and filtering, drying and firing the mixed precipitate obtained by adding oxalic acid and an organic amine base. The method according to claim 1, wherein the solution containing gallium component is at least one selected from an aqueous solution of gallium nitrate, gallium sulfate or gallium chloride, and metal gallium dissolved in nitric acid or hydrochloric acid. . The method of claim 1, wherein the aqueous zinc compound solution containing the manganese component is one or more selected from an aqueous solution of zinc acetate, zinc chloride, zinc nitrate or zinc sulfate and a solution in which metal zinc or zinc oxide is dissolved in nitric acid, hydrochloric acid or sulfuric acid. A method for producing a green light emitting phosphor, wherein the manganese component is contained in an amount of 0.01 to 3 mol%. The method of claim 1, wherein the firing is carried out for 1 to 10 hours at a temperature of 700 to 1,300 ℃ in air and reducing atmosphere.