JP2002038148A - Green phosphor, method for producing the same, and light-emitting device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a green phosphor made of a manganese-activated zinc silicate (Zn2SiO4: Mn) phosphor used for a vacuum ultraviolet ray-excited light- emitting device, such as a PDP(plasma display panel), improved so as to have a shortened afterglow time, while preventing decrease of luminance which is excited by vacuum ultraviolet rays having, for example, wavelength of <=200 nm. SOLUTION: This green phosphor comprises the finely-divided manganese- activated zinc silicate (Zn2SiO4: Mn) phosphor having an average primary particle diameter of <1 μm. The green fluorescent material is preferably used for emitting the light which is excited by the vacuum ultraviolet rays, for example, having the wavelength of <=200 nm. The finely-divided manganese-activated zinc silicate phosphor having the average primary particle diameter of <1 μm can be used not only solely, but also used after being mixed with a coarse- grained manganese-activated zinc silicate phosphor having an average primary particle diameter of 2-4 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a green phosphor suitable as a phosphor for exciting vacuum ultraviolet rays, a method for producing the same, and a light emitting device using the same.

[0002]

2. Description of the Related Art In recent years, light emitting devices using short-wavelength vacuum ultraviolet rays emitted by rare gas discharge as an excitation source of a phosphor have been developed. In such a light emitting device, a phosphor that emits light using vacuum ultraviolet light as an excitation source, that is, a vacuum ultraviolet light excited phosphor is used. As a display device using a light emitting device excited by vacuum ultraviolet light, a plasma display panel (PDP) is well known.

[0003] With the advent of the multimedia era, PDPs have characteristics such as large screens and thinness that enable digital display, which are required for displays as core devices of digital networks. That is, PDPs are attracting attention as digital display devices capable of projecting various kinds of information with high precision and high definition, and capable of increasing the screen size and thinning.

As a device for emitting light by exciting a phosphor with vacuum ultraviolet rays, not only a display device such as a PDP but also a rare gas discharge lamp utilizing discharge light emission by a rare gas such as xenon (Xe) is known. ing. Rare gas discharge lamps such as Xe discharge lamps have come to be used in applications requiring safety and the like, such as backlights for in-vehicle liquid crystal displays, instead of conventional mercury (Hg) discharge lamps. ing. Since noble gas discharge lamps do not use harmful mercury, they are also attracting attention as discharge lamps having excellent environmental safety.

What is common to the vacuum ultraviolet excitation type light emitting devices described above is that instead of the conventional ultraviolet rays (wavelength: 254 nm) from an electron beam or mercury, the excitation source of the phosphor is replaced with a conventional one.
That is, vacuum ultraviolet rays having a wavelength of 147 nm, 172 nm, or the like emitted by rare gas discharge are used. Since there are few studies on emitting phosphors in the vacuum ultraviolet region, luminous devices of the vacuum ultraviolet excitation type are empirically selected from among conventionally known phosphors that have relatively excellent emission characteristics with vacuum ultraviolet rays. Select and use.

For example, in order to realize full-color display on a PDP, phosphors that emit red, green, and blue light are required. Therefore, in the conventional full-color PDP,
(Y, Gd) BO3: Eu phosphor is used as a red phosphor, Zn2SiO4: Mn phosphor is used as a green phosphor, and BaMgAl10O17: Eu phosphor is used as a blue phosphor. In addition, in the rare gas discharge lamp, a mixture of the above-described phosphors of each color emission is generally used. (Ba, Sr) A
l12O19: Mn or (Ba, Sr) MgAl10O17: Mn
Such manganese-activated alkaline earth aluminate phosphors are also known.

[0007]

As described above, a conventional green phosphor for exciting vacuum ultraviolet light is Zn2Si.
O4: Manganese activated zinc silicate phosphor such as Mn and (B
Manganese activated alkaline earth aluminate phosphors such as a, Sr) MgAl10O17: Mn are known. Among these, a manganese-activated zinc silicate phosphor is mainly used as a green phosphor for excitation of vacuum ultraviolet rays from the viewpoint of luminance characteristics and the like.

However, a long afterglow time has been regarded as a problem with manganese-activated phosphors such as Zn2SiO4: Mn. In this regard, it is known that the afterglow time is shortened by increasing the amount of Mn. However, the luminance decreases when the Mn concentration is increased.
As described above, at present, there is a trade-off between the afterglow time and the luminance.

For these reasons, it is important to shorten the afterglow time while suppressing a decrease in luminance of the manganese-activated zinc silicate phosphor. Furthermore, in order to realize a high-luminance light-emitting device in a PDP or a rare gas discharge lamp, it is essential to increase the luminous efficiency when each color phosphor is excited by vacuum ultraviolet rays having a wavelength of 147 nm or 172 nm. . Among them, in order to improve white brightness,
In particular, it is important to increase the luminous efficiency of the green phosphor having high visibility. From such a point, there is a strong demand for further improving the luminous efficiency of the green phosphor by vacuum ultraviolet excitation.

[0010] The present invention has been made to address such a problem, and a green phosphor which has a reduced afterglow time while suppressing a decrease in luminance of a manganese-activated zinc silicate phosphor. It is intended to provide a manufacturing method thereof. Another object of the present invention is to provide a green phosphor in which the luminance of green light emission when excited by vacuum ultraviolet light is further improved. It is another object of the present invention to provide a light-emitting device having improved luminance characteristics and display characteristics by using such a green phosphor.

[0011]

The present inventors have studied various Zn2SiO4: Mn phosphors in order to achieve the above-mentioned object. As a result, the present inventors have applied the sol-gel method to the production of Zn2SiO4: Mn phosphors. As a result, a fine particle phosphor having an average primary particle diameter of less than 1 μm is obtained, and it has been found that such a fine particle phosphor of Zn2SiO4: Mn can reduce the afterglow time while suppressing the decrease in luminance. Was. Further, the fine particle phosphor of Zn2SiO4: Mn also contributes to the improvement of luminance. The fine particle phosphor of Zn2SiO4: Mn is not limited to the case where it is used alone.
It can also be used as a mixture with a SiO4: Mn phosphor (coarse particle phosphor).

The present invention has been made based on such findings, and the green phosphor of the present invention is a green phosphor composed of a manganese-activated zinc silicate phosphor as described in claim 1. The manganese-activated zinc silicate phosphor is characterized in that the manganese-activated zinc silicate phosphor is composed of fine particles having an average primary particle diameter of less than 1 μm.

According to another aspect of the present invention, there is provided a green phosphor comprising a manganese-activated zinc silicate phosphor, wherein the manganese-activated zinc silicate phosphor has an average primary particle size. It is characterized by comprising a mixture of a fine particle phosphor having a diameter of less than 1 μm and a coarse particle phosphor having an average primary particle diameter in a range of 2 to 4 μm.

The green phosphor according to the present invention is effective as a phosphor for exciting vacuum ultraviolet rays. More specifically, as described in claim 7,
It is particularly effectively used as a vacuum ultraviolet ray excited phosphor for a plasma display panel.

According to the method for producing a green phosphor of the present invention, a water-soluble manganese compound and a zinc compound are prepared in a predetermined manner in producing a green phosphor comprising a manganese-activated zinc silicate phosphor. A step of preparing an aqueous solution containing at a ratio of, and adjusting the pH of the aqueous solution to a range of 6 to 9 to generate hydroxides of manganese and zinc, then adding a predetermined amount of an alkoxide compound of silicon and mixing. A step of synthesizing the manganese-activated zinc silicate phosphor, filtering and drying a solution containing the manganese-activated zinc silicate phosphor, and firing the dried product in a reducing atmosphere to obtain an average primary particle diameter. Obtaining manganese-activated zinc silicate phosphor fine particles having a particle size of less than 1 μm.

According to the method for producing a green phosphor of the present invention, the manganese-activated zinc silicate phosphor fine particles having an average primary particle diameter of less than 1 μm and the average primary particle diameter of 2
A step of mixing manganese-activated zinc silicate phosphor coarse particles in the range of 44 μm may be included.

According to a tenth aspect of the present invention, there is provided a light emitting device including the above-described light emitting layer containing the green phosphor of the present invention. As a specific mode of the light emitting device of the present invention, for example, as described in claim 11, a light emitting layer including a blue light emitting phosphor and a red light emitting phosphor excited by vacuum ultraviolet in addition to the green phosphor, A light-emitting device which comprises a means for irradiating the light-emitting layer with vacuum ultraviolet rays and constitutes a display portion of a plasma display panel.

[0018]

Embodiments of the present invention will be described below.

The green phosphor of the present invention is substantially composed of Zn2S
iO4: A manganese-activated zinc silicate phosphor having a composition represented by Mn. Here, the activation amount of Mn is preferably in the range of 3 to 13 mol% with respect to the phosphor base material (Zn2SiO4) in order to obtain good emission chromaticity and high luminance as a green phosphor.

Such a green phosphor of the present invention is suitable as a phosphor for exciting vacuum ultraviolet rays. Specifically, for example, it is suitable for applications in which light is emitted by excitation with ultraviolet light (vacuum ultraviolet light) having a short wavelength of 200 nm or less. Wavelength
Xe gas, Xe gas
It is emitted by discharge using a rare gas such as -Ne gas (rare gas discharge), and practically, vacuum ultraviolet rays having a wavelength of 147 nm or vacuum ultraviolet rays having a wavelength of 172 nm are used.

The green phosphor of the present invention is the above-mentioned manganese-activated zinc silicate phosphor having an average primary particle diameter of less than 1 μm, and an aggregate of fine particle phosphors having an average primary particle diameter of less than 1 μm. It has. Such finely divided manganese-activated zinc silicate phosphor can be obtained with good reproducibility by applying a sol-gel method described in detail below.

As described above, by making the average primary particle diameter of the manganese-activated zinc silicate phosphor finer than 1 μm, the afterglow time can be shortened while suppressing a decrease in emission luminance. Such a short afterglow is particularly effective when excited by vacuum ultraviolet light having a wavelength of 200 nm or less.

Further, the manganese-activated zinc silicate phosphor finely divided as described above not only improves the luminance as a powder, but also increases the density of a phosphor layer (light-emitting layer) containing the same. It is possible to further improve the emission luminance of green light emission. Such an improvement in light emission luminance
It can be obtained particularly effectively when excited by vacuum ultraviolet light having a wavelength of 200 nm or less as described above.

The average primary particle diameter of the manganese-activated zinc silicate phosphor according to the present invention is preferably 1 μm or less. The manganese-activated zinc silicate phosphor has a primary particle size of
It is preferable that fine particles having a size of less than 1 μm are contained in an amount of 80% by mass or more.
According to such a manganese-activated zinc silicate phosphor, the effect of improving the emission luminance and the effect of suppressing the afterglow time can be more remarkably obtained.

Here, the average primary particle diameter of the manganese-activated zinc silicate phosphor of the present invention indicates a value measured by the Blaine method. Specifically, using a device as shown in FIG. 3, first, a phosphor is packed in a cell and compressed with a plunger at a constant pressure. A cell in which a certain gap and a compact are formed is brought into close contact with a manometer, and the liquid level in the manometer is raised to A by an aspirator. Turn off the aspirator, measure the time for the liquid level to drop from B to C, calculate the specific surface area S based on the following equation (1), and calculate the specific surface area S based on the following equation (2) from the obtained specific surface area S. The average particle diameter D is calculated.

S = S0 (ρ0 / ρ) (t / t0) 1/2 · (1-e0) / e03 / 2 · e3 / 2 / (1-e) (1) D = 6 / (ρ · S) ... (2) (where, S is the specific surface area of the unknown sample, ρ is the specific gravity of the unknown sample, e is the porosity of the unknown sample, t is the liquid surface descent time of the unknown sample, and S0 is the specific surface area of the standard sample. , Ρ0 is the specific gravity of the standard sample,
e0 is the porosity of the standard sample, t0 is the liquid surface falling time of the standard sample, and D is the average particle size. Further, the ratio of the fine particles having a primary particle size of less than 1 μm is obtained from, for example, a scanning electron microscope (SEM) photograph. Shall be.

The green phosphor of the present invention as described above, that is, the finely divided manganese-activated zinc silicate phosphor (fine particle phosphor) exhibits the above-mentioned effects when used alone. However, for example, it is also possible to use a mixture with a manganese-activated zinc silicate phosphor (coarse particle phosphor) obtained by a usual firing method. As the coarse particle phosphor, it is preferable to use a manganese-activated zinc silicate phosphor having an average primary particle diameter in the range of 2 to 4 μm.

As described above, by mixing and using the fine particle phosphor of manganese-activated zinc silicate and the coarse particle phosphor, the effect of shortening the afterglow and the effect of improving the brightness by the fine particle phosphor can be applied to the entire mixed phosphor. It works effectively for them. In particular, by attaching the fine particle phosphor to the surface of the coarse particle phosphor, the effect of the fine particle phosphor can be more effectively exerted. On top of that, by using a coarse-grained manganese-activated zinc silicate phosphor in combination with a normal firing method,
The manufacturing cost of the green phosphor can be reduced.

That is, the manganese-activated zinc silicate phosphor to which the sol-gel method described later is applied slightly increases the production cost as compared with the ordinary calcination method. By using the phosphor in combination with the zinc silicate phosphor, it is possible to obtain the effect of shortening the afterglow and the effect of improving the luminance by the fine particle phosphor, and also to reduce the production cost of the green phosphor.

The average primary particle diameter of the coarse-grained manganese-activated zinc silicate phosphor is preferably in the range of 2 to 4 μm as described above. The average primary particle diameter of the coarse particle phosphor is 2
If it is less than μm, the effect of mixing with the fine particle phosphor cannot be sufficiently obtained. On the other hand, if the average primary particle diameter of the coarse particle phosphor exceeds 4 μm, the density of the phosphor layer (light-emitting layer) may be reduced when the device is manufactured, and the luminance may be reduced.

The mixing ratio between the fine particle phosphor and the coarse particle phosphor of manganese-activated zinc silicate is not particularly limited, but in order to more effectively obtain the effect of the fine particle phosphor, the mixing ratio is determined by mass. Preferably, the ratio is in the range of 1 to 50%. That is, if the ratio of the fine particle phosphor in the mixture is less than 1% by mass, the effect of the fine particle phosphor may not be sufficiently obtained. Further, in order to reduce the production cost of the manganese-activated zinc silicate phosphor as a mixture, the ratio of the fine particle phosphor is preferably set to 50% or less by mass ratio. The mixing ratio of the fine particle phosphor is more preferably in the range of 5 to 40% by mass, and the mixing ratio of the fine particle phosphor is preferably 10% or less by mass.

The green phosphor of the present invention can be manufactured, for example, as follows. First, the method for producing the fine manganese-activated zinc silicate phosphor will be described in detail.

That is, an aqueous solution containing a water-soluble manganese compound and a water-soluble zinc compound at a predetermined ratio is prepared.
Specifically, water-soluble compounds that become Mn ions or Zn ions in water, such as chlorides and nitrates of Mn and Zn, are respectively prepared by Zn2SiO4: Mn (Mn content is, for example, Zn).
A predetermined amount is weighed so as to satisfy the composition formula (3 to 13 mol% based on 2SiO4 base), and these are weighed and poured into pure water heated to about 60 to 80 ° C, and well stirred to dissolve.

Next, for example, NH4OH is added to the above aqueous solution.
Or NaOH is added to adjust the pH of the aqueous solution containing Mn ions and Zn ions to a range of 6 to 9. By this pH adjustment, hydroxides such as Zn (OH) 2 and Mn (OH) 2 are generated. Then, an alkoxide compound of silicon weighed according to the above composition formula, for example, ethyl silicate (Si
(OC2H5) 4) is added and stirred, for example, for 2-3 hours.
As described above, the alkoxide compound such as ethyl silicate is added, and the mixture is sufficiently stirred to hydrolyze the ethyl silicate or the like on the surface of the hydroxide of Zn and Mn.
2SiO4: Mn is synthesized.

Thereafter, the solution containing Zn2SiO4: Mn is washed, filtered and dried, and the dried product is calcined in a reducing atmosphere, for example, at 800 to 1100 ° C. for 3 to 6 hours to obtain an average primary solution. A manganese-activated zinc silicate phosphor (particle phosphor) having a particle diameter of less than 1 μm can be obtained with good reproducibility.

When the above-mentioned finely divided manganese-activated zinc silicate phosphor is used by mixing it with a coarse-grained manganese-activated zinc silicate phosphor obtained by a usual firing method, for example, the coarse-particle manganese-activated zinc silicate phosphor is added to pure water. After dispersing the particles (average primary particle diameter: 2 to 4 μm), a fine particle phosphor (average primary particle diameter: less than 1 μm) similarly dispersed in pure water is added, and the mixture is stirred, for example, for about 1 hour. This is filtered and dried to obtain a manganese-activated zinc silicate phosphor in which a fine particle phosphor is attached to the surface of a coarse particle phosphor.

The green phosphor of the present invention has a wavelength of 147 nm or 1
A light-emitting device using a vacuum ultraviolet ray such as 72 nm as a phosphor excitation source, specifically a plasma display panel (PDP)
And a light source of a rare gas discharge lamp such as a Xe discharge lamp. Since the green phosphor of the present invention has excellent afterglow characteristics, it is particularly suitable for a green phosphor for a full-color PDP.

When the green phosphor of the present invention is applied to a display portion of a full-color PDP, the green phosphor according to the present invention (green-light-emitting vacuum ultraviolet-excited phosphor) and a known blue and red light-emitting vacuum ultraviolet-excited phosphor are used. Is formed on one of a pair of substrates having an electrode group arranged in a matrix, and the space between the substrates is hermetically sealed with a rare gas such as Xe. Then, a rare gas discharge is generated between the electrodes of the pair of substrates, and the phosphor layer is caused to emit light by vacuum ultraviolet rays generated by the rare gas discharge. These constitute a display unit of the plasma display panel.

When the VUV-excited phosphor of the present invention is applied to a rare gas discharge lamp, the green phosphor of the present invention is mixed with known blue and red phosphors, and the mixed phosphor (3 A light emitting layer (phosphor layer) is formed by applying a wavelength type white light emitting phosphor on the inner surface of the glass bulb.
Electrodes are attached to both ends of the glass bulb, and the bulb is sealed while being filled with a rare gas such as Xe gas.
A voltage is applied between the electrodes at both ends to generate a rare gas discharge,
The phosphor layer is caused to emit light by vacuum ultraviolet rays generated by the rare gas discharge. These constitute a rare gas discharge lamp.

The light emitting device of the present invention has the above-described configuration, and is specifically used as a display portion of a plasma display panel or a rare gas discharge lamp. Since the green phosphor of the present invention has excellent luminance and afterglow characteristics, display characteristics of a plasma display panel or the like using the same can be enhanced.

Various known phosphors can be used as the blue and red light emitting vacuum ultraviolet excited phosphors.
Although not particularly limited to these, for example, as a vacuum-ultraviolet-excited phosphor emitting blue light, BaMgAl10O1
7: Eu phosphor and the like, and (Y, Gd) BO3: Eu phosphor and (Y, Gd) 2O3: Eu phosphor can be used as a red-light-emitting vacuum ultraviolet excitation phosphor.

[0042]

Next, specific examples of the present invention and evaluation results thereof will be described.

Example 1 and Comparative Example 1 First, Zn (NO 3) 2 and MnCl 2 were used as phosphor raw materials.
And Si (OC2H5) 4 were prepared. Zn (NO3) 2 is 2mo
l, MnCl2 was weighed to be 0.5 mol,
It was dissolved in 300 cc of pure water (DW) heated to ℃. Next, NH4OH was added to this aqueous solution to adjust the pH of the aqueous solution to 8.
Was adjusted. After pH adjustment, the aqueous solution was stirred for 1 hour. During this time, the water temperature was maintained at 60 ° C. Then, 1 mol of Si (OC
Ethanol equivalent to 2H5) 4 was added and stirred for 2-3 hours.

After the stirred aqueous solution was allowed to stand, it was filtered and dried. The dried product was once sieved, and then baked in a reducing atmosphere at, for example, 1000 ° C. for 3 hours to obtain a desired Zn 2 SiO 4: Mn phosphor. When the average primary particle diameter of the obtained Zn2SiO4: Mn phosphor was measured by the Blaine method described above, it showed a value of 0.47 μm. FIG. 1 shows an SEM photograph of the Zn2SiO4: Mn phosphor particles. As is clear from the SEM photograph of FIG. 1, the primary particle diameter of almost all the phosphor particles is 1 μm.
It turns out that it is less than.

Next, the obtained Zn2SiO4: Mn phosphor was irradiated with vacuum ultraviolet rays having a wavelength of 147 nm, and the emission luminance, emission chromaticity and afterglow time were measured. Afterglow time is
The time until the luminance after blocking the ultraviolet rays became 1/10 of the luminance immediately before the blocking was defined as the time. The emission luminance was obtained as a relative luminance when the luminance of a Zn2SiO4: Mn phosphor (Comparative Example 1) having an average primary particle diameter of 2.30 μm by a conventional firing method was set to 100. FIG. 2 shows Zn2SiO4: Mn of Comparative Example 1.
3 shows an SEM photograph of phosphor particles.

As a result, the emission luminance of the particulate Zn2SiO4: Mn phosphor obtained in Example 1 was 105%, and the emission chromaticity was (0.23, 0.72). The afterglow time was the same as in Comparative Example 1.
In contrast to 14 ms, it was 11 ms in the first embodiment. Thus, the Zn2SiO4: Mn phosphor of Example 1 is different from Comparative Example 1
It can be seen that the afterglow time is shorter and the luminance is also improved as compared with the phosphor of Example 1. Further, the chromaticity of green light emission of Example 1 is equivalent to that of Comparative Example 1.

PDPs were formed using the Zn2SiO4: Mn phosphors of Example 1 and Comparative Example 1, respectively, and the emission luminance and emission chromaticity when each PDP was turned on were measured. As a result, the light emission luminance of the PDP using the phosphor of Example 1 was lower than that of the PDP using the phosphor of Comparative Example 1.
The light emission luminance of P was 108% when the light emission luminance was 100, and the light emission chromaticity was (x, y) = (0.23, 0.72). Example 1
It is considered that the enhancement of the brightness due to the fineness of the phosphor due to the fine particles of the phosphor contributes to the improvement of the brightness.

Example 2 First, 2 mol of Zn (NO 3) 2 and Mn
0.8 mol of Cl2 and 1 mol of Si (OC2H5) 4 were prepared. 2m
ol of Zn (NO3) 2 and 0.8 mol of MnCl2 were dissolved in 300 cc of pure water (DW) heated to 60 ° C. next,
The pH of the aqueous solution was adjusted to 8 by adding NH4OH to the aqueous solution. After pH adjustment, the aqueous solution was stirred for 1 hour. During this time,
The water temperature was kept at 60 ° C. Then, 1 mol of Si (OC2H
5) Ethanol equivalent to 4 was added and stirred for 2-3 hours.

After the aqueous solution after stirring was allowed to stand, it was filtered and dried. After the dried product was once sieved, it was baked in a reducing atmosphere at, for example, 1000 ° C. for 6 hours to obtain a desired Zn2SiO4: Mn phosphor. When the average primary particle diameter of the obtained Zn2SiO4: Mn phosphor was measured by the Blaine method described above, it was found to be 0.57 μm.

The particulate Zn2Si thus obtained is
Example 1 shows the emission luminance, emission chromaticity and afterglow time when the O4: Mn phosphor was irradiated with vacuum ultraviolet light, and the emission luminance and emission chromaticity of a PDP manufactured using this phosphor.
The measurement was performed in the same manner as described above. Table 1 shows the results.

Example 3 First, 2 mol of ZnCl 2 and MnCl 2 were used as phosphor materials.
Was prepared, and 1 mol of Si (OC2H5) 4 was prepared. 2 mol ZnCl 2 and 0.5 mol MnCl 2 were heated to 80 ° C.
It was dissolved in 300 cc of pure water (DW). Next, NH4OH was added to the aqueous solution to adjust the pH of the aqueous solution to 8. pH
After the adjustment, the aqueous solution was stirred for 1 hour. During this time, the water temperature is 80 ℃
Held. Next, ethanol equivalent to 1 mol of Si (OC2H5) 4 was added and stirred for 2 to 3 hours.

After the aqueous solution after stirring was allowed to stand, it was filtered and dried. The dried product was once sieved, and then baked in a reducing atmosphere at, for example, 1000 ° C. for 3 hours to obtain a desired Zn 2 SiO 4: Mn phosphor. When the average primary particle diameter of the obtained Zn2SiO4: Mn phosphor was measured by the Blaine method described above, it showed a value of 0.44 μm.

The fine-particle Zn2Si thus obtained is
Example 1 shows the emission luminance, emission chromaticity and afterglow time when the O4: Mn phosphor was irradiated with vacuum ultraviolet light, and the emission luminance and emission chromaticity of a PDP manufactured using this phosphor.
The measurement was performed in the same manner as described above. Table 1 shows the results.

Example 4 First, 2 mol of ZnCl 2 and MnCl 2 were used as phosphor materials.
Was prepared and 1 mol of Si (OC2H5) 4 was prepared. 2 mol ZnCl 2 and 0.8 mol MnCl 2 were heated to 80 ° C.
It was dissolved in 300 cc of pure water (DW). Next, NH4OH was added to the aqueous solution to adjust the pH of the aqueous solution to 8. pH
After the adjustment, the aqueous solution was stirred for 1 hour. During this time, the water temperature is 80 ℃
Held. Next, ethanol equivalent to 1 mol of Si (OC2H5) 4 was added and stirred for 2 to 3 hours.

After the stirred aqueous solution was allowed to stand, it was filtered and dried. After the dried product was once sieved, it was baked in a reducing atmosphere at, for example, 1000 ° C. for 4 hours to obtain a desired Zn 2 SiO 4: Mn phosphor. When the average primary particle diameter of the obtained Zn2SiO4: Mn phosphor was measured by the Blaine method described above, a value of 0.52 μm was shown.

The thus obtained fine-grained Zn2Si
Example 1 shows the emission luminance, emission chromaticity and afterglow time when the O4: Mn phosphor was irradiated with vacuum ultraviolet light, and the emission luminance and emission chromaticity of a PDP manufactured using this phosphor.
The measurement was performed in the same manner as described above. Table 1 shows the results.

[0057]

[Table 1] As is evident from Table 1, fine-grained Zn according to the present invention
It can be seen that the 2SiO4: Mn phosphor has excellent brightness when excited by vacuum ultraviolet light, and has a short afterglow time. Therefore, by forming a light emitting device such as a display portion of a PDP using such a green phosphor, it is possible to improve the light emission characteristics and display characteristics.

Example 5 First, 30 g of the Zn2SiO4: Mn coarse particle phosphor (average primary particle diameter: 2.30 μm) of Comparative Example 1 was dispersed in 100 cc of pure water. On the other hand, the Zn2SiO
4: Fine particle phosphor of Mn (average primary particle diameter: 0.47 μm) 1.
5 g was dispersed in 15 cc of pure water.

Next, the dispersion containing the fine particle phosphor was added to the dispersion containing the coarse particle phosphor described above, and the mixture was stirred for 1 hour. After stirring, the mixture is filtered and dried to obtain Zn2S
ZnO 4: Mn on the surface of iO 4: Mn phosphor coarse particles
A phosphor to which the phosphor fine particles were attached was obtained.

The Zn2SiO4: Mn phosphor thus obtained is irradiated with vacuum ultraviolet rays to emit light, emit light, have a chromaticity and afterglow time.
The light emission luminance and light emission chromaticity of DP were measured in the same manner as in Example 1. Table 2 shows the results.

Examples 6 to 8 In the same manner as in Example 5 except that the ratio of the fine particle phosphor mixed with the coarse particle phosphor (shown in Table 2) was changed, Zn2
SiO4: Mn phosphor Zn2SiO4: M
Each phosphor to which n phosphor fine particles were adhered was obtained. The emission luminance, emission chromaticity, and afterglow time when the Zn2SiO4: Mn phosphor was irradiated with vacuum ultraviolet light, and the emission luminance and emission chromaticity of the PDP manufactured using this phosphor were the same as in Example 1. Was measured. Table 2 shows the results.

[0062]

[Table 2] As is evident from Table 2, the Zn2SiO4 according to the invention:
It can be seen that the mixed phosphor of Mn has excellent brightness when excited by vacuum ultraviolet light, and has a short afterglow time. Therefore,
By forming a light emitting device such as a display portion of a PDP using such a green phosphor, it is possible to improve its light emitting characteristics and display characteristics.

[0063]

As described above, according to the green phosphor of the present invention, the afterglow time can be shortened while suppressing the decrease in emission luminance. Further, the emission luminance can be further improved as well as suppressed. Therefore, by using such a green phosphor of the present invention for a light emitting device such as a PDP, it is possible to provide a light emitting device having excellent light emitting characteristics and display characteristics.

[Brief description of the drawings]

FIG. 1 shows Zn2Si obtained according to Example 1 of the present invention.
5 is an SEM photograph showing an enlarged shape of O4: Mn phosphor particles.

FIG. 2 is an SEM photograph showing an enlarged shape of Zn2SiO4: Mn phosphor particles of Comparative Example 1.

FIG. 3 is a view for explaining a method for measuring the average particle diameter D of the powder by the Blaine method.

Claims (11)

[Claims] 1. A green phosphor comprising a manganese-activated zinc silicate phosphor, wherein the manganese-activated zinc silicate phosphor is composed of fine particles having an average primary particle diameter of less than 1 μm. Phosphor. 2. The green phosphor according to claim 1, wherein the manganese-activated zinc silicate phosphor contains at least 80% by mass of fine particles having a primary particle diameter of less than 1 μm. 3. A green phosphor comprising a manganese-activated zinc silicate phosphor, wherein the manganese-activated zinc silicate phosphor has an average primary particle diameter of less than 1 μm and an average primary particle diameter of 2 to 4 μm. A green phosphor comprising a mixture with a coarse particle phosphor in the range of: 4. The green phosphor according to claim 3, wherein the fine particle phosphor is attached to a surface of the coarse particle phosphor. 5. The green phosphor according to claim 3, wherein a mixing ratio of the fine particle phosphor is in a range of 1 to 50% by mass. 6. The green phosphor according to claim 1, wherein the green phosphor is used as a phosphor for exciting a vacuum ultraviolet ray. 7. The green phosphor according to claim 6, wherein the green phosphor is used as a vacuum ultraviolet excitation phosphor for a plasma display panel. 8. When producing a green phosphor comprising a manganese-activated zinc silicate phosphor, a step of preparing an aqueous solution containing a water-soluble manganese compound and a zinc compound in a predetermined ratio, and adjusting the pH of the aqueous solution to 6 to After adjusting the manganese and zinc hydroxide to a range of 9, a predetermined amount of silicon alkoxide compound is added and mixed to synthesize the manganese-activated zinc silicate phosphor, Filtering and drying the solution containing the active zinc silicate phosphor, and firing the dried product in a reducing atmosphere to obtain manganese-activated zinc silicate phosphor fine particles having an average primary particle diameter of less than 1 μm. A method for producing a green phosphor. 9. The method for producing a green phosphor according to claim 8, wherein the manganese-activated zinc silicate phosphor fine particles having an average primary particle diameter of less than 1 μm have an average primary particle diameter of 2 to 4 μm. A green phosphor comprising a step of mixing manganese-activated zinc silicate phosphor coarse particles. 10. The method according to claim 1, wherein:
A light-emitting device comprising a light-emitting layer containing the green phosphor described in the above item. 11. The light emitting device according to claim 10, wherein in addition to the green phosphor, the light emitting layer includes a blue phosphor and a red phosphor excited by vacuum ultraviolet light, and means for irradiating the light emitting layer with vacuum ultraviolet light. And a display unit of a plasma display panel.