JP2000226574A - Blue-color fluorescent material for plasma display panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject fluorescent material substantially freed from decline in luminous efficiency or change in luminescent color due to baking in the production of PDP panels. SOLUTION: This blue-color fluorescent material consists of an aluminate of the compositional formula (Ba1-mSrm)iMgAljOn:Euk (0<=m<=0.25; 1.0<=i<=1.8; 12.7<=j<=21.0; 0.01<=k<=0,20; 21.0<=n<=34.5); wherein n is such a value as to be unequivocally determined from the respective valences of the oxygen atom and the other atoms constituting the aluminate, and calculated by the equation: [(2(1-m)+2m)i+2+3j+2k]/2=(2i+3j+2k+2)/2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blue phosphor for a plasma display panel (PDP), and more particularly, to a novel blue phosphor which has no or drastic decrease in luminous efficiency or color change due to baking during a PDP manufacturing process. And a blue phosphor for PDP.

[0002]

2. Description of the Related Art Recently, a plasma display panel (PD) has been considered as a display (image display device) replacing a plow tube (CRT) because it is considered that a large screen, high image quality, high definition, and digitization can be supported.
P) is attracting attention. Currently, a blue phosphor of aluminate mainly developed as a blue phosphor for PDP is used in combination with a red phosphor and a green phosphor. This aluminate blue phosphor is BaMgAl ₁₄
O ₂₃ : Eu ²⁺ or BaMgAl ₁₀ O ₁₇ : Eu
²⁺ (often referred to as BAM phosphor) is currently in use (1998 FPD Technology Taizen, p. 474).
478, electronic journal).

[0003] One of the major problems of such an aluminate blue phosphor is thermal deterioration due to baking treatment in the PDP manufacturing process. That is, a phosphor used for a PDP or the like is generally mixed with a binder (usually an organic compound), applied to a predetermined portion, and then heated to 400 to 500 ° C. in order to burn and remove the binder. Due to this treatment, degradation of the obtained phosphor, such as a decrease in luminous efficiency and a change in emission color, is observed. In particular, the thermal degradation phenomenon of blue phosphor is remarkable (1998 FPD Technology Taizen, pp. 474-478, electronic journal).

[0004] As measures against the thermal deterioration of the aluminate blue phosphor, attempts have been made to lower the heating temperature and to select an effective binder material, but this has not been a fundamental solution. As a measure against thermal degradation from the side of the phosphor, a method of coating the surface of the phosphor with a stable substance has been proposed.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a PD
It is an object of the present invention to provide a new type of blue phosphor for aluminate PDP which has reduced or drastically reduced the emission efficiency and the change in emission color due to baking during P panel production.

[0006]

SUMMARY OF THE INVENTION The present inventors have developed an aluminate blue phosphor currently used, for example, BaMgA.
l ₁₄ O ₂₃ : Eu ²⁺ or BaMgAl
A new type of aluminate phosphor having a composition different from that of ₁₀ O ₁₇ : Eu ²⁺ , having a different crystal structure, and having extremely reduced thermal degradation due to baking during PDP panel production has been found.

Thus, the present invention provides a composition represented by the formula (Ba _{1-m
Sr m) i MgAl j O n} : Eu k at aluminate (0 ≦ m ≦ represented 0.25,1.0 ≦ i ≦ 1.8,12.7 ≦ j ≦ 21.0,0.0
(1 ≦ k ≦ 0.20, 21.0 ≦ n ≦ 34.5) A blue phosphor for a plasma display panel is provided.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The phosphor of the present invention has a composition formula (Ba)
_{1-m Sr m) i MgAl} j O n: Eu k at aluminate represented (0 ≦ m ≦ 0.25,1.0 ≦ i ≦ 1.8,12.7 ≦ j ≦ 21.
0, 0.01 ≦ k ≦ 0.20, 21.0 ≦ n ≦ 34.5). However, the value of n relating to the oxygen atom is uniquely determined from the valences of the oxygen atom and other atoms constituting the aluminate, and specifically, the formula [(2 (1-m) + 2m ) I + 2 + 3j + 2k]
/ 2 = (2i + 3j + 2k + 2) / 2.

In addition to aluminate phosphors represented by BAM phosphors, phosphors for PDP are disclosed in JP-A-8-11567.
3 is described. This Japanese Patent Application Laid-Open No. 8-11567
The phosphor Ba _1-x Eu _x MgAl ₁₀ described in _No. 3
O ₁₇ (0.05 ≦ x ≦ 0.5) is BaMgAl
₁₄ O ₂₃ : This is an improvement in the life characteristics of Eu ²⁺ .

The phosphor of the present invention is disclosed in Japanese Patent Application Laid-Open No. 8-11567.
The phosphor has a larger amount of barium and aluminum than the phosphor described in No. 3.

The present inventors have paid attention to the phenomenon of deterioration of the blue phosphor for PDP due to baking, and as a result of repeated studies, have found that BaMgAl which is currently used for PDP panels is used.
₁₄ O ₂₃ : Eu ²⁺ or BaMgAl ₁₀ O ₁₇ :
It has been found that when the amount of barium and aluminum is increased from the Eu ²⁺ blue phosphor, the resulting phosphor has a significantly reduced decrease in luminous efficiency and a change in luminescent color even after baking. In addition, it has been clarified that even when barium is partially replaced with strontium, it is effective against thermal deterioration due to baking.

The composition formula (Ba) of the present invention_1-mSr_m)_iMg
Al_jO_n: Eu_kAluminate blue phosphor represented by
(0 ≦ m ≦ 0.25, 1.0 ≦ i ≦ 1.8, 12.7 ≦ j ≦ 21.0, 0.01
≤ k ≤ 0.20, 21.0 ≤ n ≤ 34.5)
BaMgAl used ₁₀O₁₇: Eu²⁺No
It has a different crystal structure from the blue phosphor. Detail
Then, BaMgAl₁₀O₁₇: Eu²⁺Crystal structure of
Then, the (008) and (110) plane X-ray diffraction peaks overlap.
However, in the crystal structure of the phosphor of the present invention, (008)
And (110) plane X-ray diffraction peaks are separated. Further
The X-ray diffraction peaks of the (112) and (107) planes
However, the former is clearly divided, but the latter tends to overlap.
(See FIG. 1). That is, from these facts
As will be appreciated, the aluminates of the present invention have been previously known.
BaMgAl₁₀O₁₇: Eu²⁺like
The crystal lattice constants a and b are smaller than those of the aluminate.
And the lattice constant c is large (c / a or c
/ B increased from 0.042% to 0.53%), all
It has a distinct crystal structure.

[0013] In accordance with the present invention, the composition formula (Ba _1-m Sr _{m)
i MgAl j O n: Eu k} (0 ≦ m ≦ 0.25,1.0 ≦ i ≦ 1.
8, 12.7 ≦ j ≦ 21.0, 0.01 ≦ k ≦ 0.20, 21.0 ≦ n ≦ 34.
The detailed reason why the thermal degradation phenomenon caused by baking is drastically reduced by adopting the phosphor composed of 5) is not clear yet, but is presumed as follows: BaMgAl ₁₀ O
_{1 7:} aluminate phosphors such as Eu ²⁺ is, beta comprises a-alumina structure, which largely adopting a structure in which it was laminated configured spinel blocks as skeleton with alumina, referred to as conductive layer on the interlayer Where the pair of alkaline earth metal and oxygen ion is located and the emission center (Eu)
²⁺ ) doped structures exist. Composition formula of the present invention _{(Ba 1-m Sr m)} i MgAl j O n: Eu k (0 ≦ m ≦
0.25, 1.0 ≦ i ≦ 1.8, 12.7 ≦ j ≦ 21.0, 0.01 ≦ k ≦ 0.2
0, 21.0 ≦ n ≦ 34.5) is BaMgAl
_It has a β-alumina structure like an aluminate phosphor such as ₁₀ O ₁₇ : Eu ²⁺ , but the crystal lattice constant changes due to an increase in the amount of barium and aluminum, and the ion arrangement of the spinel block and the conductive layer is different. . This makes it difficult for the luminescent center (Eu ²⁺ ) to be oxidized to Eu ³⁺ or that the crystal structure itself has become more stable, so that thermal degradation due to baking may have been drastically reduced in the phosphor of the present invention. unknown.

Thus, according to the present invention, it is possible to obtain a blue phosphor for PDP with reduced thermal degradation phenomenon even by baking in which the binder is removed at 400 to 500 ° C. in an oxidizing atmosphere. In particular, a blue phosphor with a very small change in emission color can be obtained even by baking at 400 to 500 ° C.

The blue phosphor of the present invention may be prepared by mixing raw materials (generally as oxides, carbonates, or hydroxides) of each metal with a predetermined composition, or, if necessary, by using a reaction accelerator (for example, fluorine). (Aluminum chloride), followed by mixing and baking. At the beginning of firing, one or more firings may be performed in an oxidizing atmosphere, but finally, at 1300 ° C. in an inert gas or reducing atmosphere.
In the above, firing is performed for at least one hour.

The point of producing the blue phosphor of the present invention lies in the compounding ratio of the raw materials and the firing step. By strictly adjusting the compounding ratio of the raw materials and firing under sufficient time and temperature conditions, the desired composition is obtained. Is obtained. Further, the fact that it has a crystal structure different from that of a normal aluminate can be confirmed by, for example, X-ray diffraction.
In general, 147 nm vacuum ultraviolet rays by xenon discharge are applied to excite the phosphor for PDP.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The characteristics of the present invention will be described below.
Therefore, an example will be described, but the present invention is limited by this example.
It is not done.Example 1  BaCO₃ 1.32mol 4MgCO₃・ Mg (OH)₂・ 3H₂O 0.20mol Al₂O₃ 8.20 mol Eu₂O₃ 0.07mol AlF₃ 0.27mol

After mixing the raw materials having the above composition, firing (at a maximum temperature of 1600 ° C. for 3 hours, atmosphere: 10 vol% H ₂ /
N ₂ ), pulverize, classify, and dry to obtain Ba _1.32 MgAl
_{16.4 0} O _27.06 : Divalent E represented by the composition formula Eu _0.14
A u-activated blue light-emitting barium aluminate phosphor was obtained. For comparison, normal composition (conventional composition) Ba _0.9 MgAl _{1 0}
A phosphor of O ₁₇ : Eu _0.1 was simultaneously produced under the same conditions.
The obtained phosphor and an aluminate phosphor of normal composition (Ba)
One example of an X-ray diffraction chart of _0.9 MgAl ₁₀ O ₁₇ : Eu _0.1 ) is shown in FIG. 1 (measurement conditions: X-ray source to CuKα; tube voltage to 40 kV; tube current to 30 mA; scanning speed to 2).
Degree 2θ / min; scattering slit (SS) to 1 degree; divergence slit (DS) to 1 degree; light receiving slit (RS) to 0.3
mm). As shown in this X-ray diffraction chart, Ba _1.32 MgAl _{16.4 0} O _27.06 consisting of the present invention: the crystal structure of the Eu _0.14 phosphor, conventional Ba _0.9 MgAl
₁₀ O ₁₇ : different from the crystal structure of Eu _0.1 (2θ = 3
Around 1.5 degrees or 33 degrees). The respective crystal lattice constants are as _follows : a _1.32 MgAl _16.40 O _27.06 : Eu _0.14 a
= B = 5.6167 (6) and c = 22.668 (3) and Ba _0.9
A = b = 5.6247 for MgAl ₁₀ O ₁₇ : Eu _0.1 (2)
And c = 22.634 (1).

The obtained phosphor and a normal composition Ba _0.9 MgA
l ₁₀ O _17: phosphor oxidizing atmosphere of Eu _0.1 (atmosphere)
The resultant was kept at 500 ° C. for 30 minutes to simultaneously perform a baking treatment. The phosphor before and after baking was irradiated with vacuum ultraviolet light of 147 nm using a self-made microwave oscillation Xe vacuum ultraviolet light source, and the emission intensity and emission color were measured. 147
Table 1 shows changes in emission characteristics before and after baking due to nm excitation.

The fluctuation rate of the chromaticity y of the phosphor before and after baking is calculated as follows. Fluctuation rate (%) of chromaticity y = (△ y / y ₀ ) × 100 = ((y _t −y ₀ ) / y ₀ ) × 100 y ₀ is the chromaticity y value of the phosphor before baking, y _t Represents the chromaticity y value of the phosphor after baking (at temperature t ° C.),
When the variation rate (%) = 0, it indicates that the chromaticity y value before and after baking does not change. The chromaticity y value is a measure of the color purity of a color display, and indicates that the larger the value, the worse the color purity.

The fluctuation rate of the emission intensity of the phosphor after baking is calculated as follows. Variation rate of the emission intensity (%) = (△ I / I 0) × 100 = ((I t -I 0) / I 0) × 100 I 0 is the emission intensity of the phosphor before baking, I _t is baked ( Represents the emission intensity of the phosphor (at a temperature t ° C.)
When the fluctuation rate (%) = 0, it indicates that the emission intensity before and after baking does not change.

[0022] As understood from Table 1, the composition formula in accordance with the present invention _{(Ba 1-m Sr m)} i MgAl j O n: Eu k (0
≦ m ≦ 0.25, 1.0 ≦ i ≦ 1.8, 12.7 ≦ j ≦ 21.0, 0.01 ≦ k
≤ 0.20, 21.0 ≤ n ≤ 34.5), the change in chromaticity y and the decrease in emission intensity are extremely small even after baking.

[0023]

[Table 1]

[0024] Example 2: by a method analogous to that described in Example _{1, (Ba 1-m Sr} m) i MgAl j O n: E
u _k (0 ≦ m ≦ 0.25, 1.0 ≦ i ≦ 1.8, 12.7 ≦ j ≦ 21.0,
0.01 ≦ k ≦ 0.20, 21.0 ≦ n ≦ 34.5)
Various phosphors having different i, j, k, and m and phosphors deviating from the composition range of the present invention were adjusted, the baking temperature was changed (each temperature was maintained for 30 minutes), and the chromaticity y and emission intensity were changed. The variability was measured. Table 2 shows the composition of these phosphors.
FIG. 2 shows the fluctuation rate of the chromaticity y of the phosphor after baking.
FIG. 3 shows the fluctuation rate of the light emission intensity. As can be understood from Table 2, FIG. 2 and FIG. 3, the blue phosphor in the composition range of the present invention undergoes very little thermal deterioration even after baking at 400 to 500 ° C.

[0025]

[Table 2]

[Brief description of the drawings]

FIG. 1 is an X-ray diffraction chart showing the structures of one example of the phosphor of the present invention and a phosphor of a normal composition for comparison.

FIG. 2 is a graph showing a variation rate of chromaticity y after baking processing in the phosphor of the present invention and a comparative example.

FIG. 3 is a graph showing the fluctuation rate of the emission intensity after baking treatment in the phosphor of the present invention and a comparative example.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Kanekin Yokota 3330 Nakatsukuma, Kitamoge-cho, Miyomoto-gun, Saga Prefecture Inside the Saga Plant of Daiden Co., Ltd. Inside the Saga Plant of Denden Co., Ltd. No. 1 Inside Shanghai Yulong Colored Metal Co., Ltd. (72) Inventor Chiang Kenping No. 1 East East Road, Baoshan District, Shanghai, China F-term inside Shanghai Yulong Colored Metal Co., Ltd. 4H001 XA08 XA12 XA13 XA38 XA56 YA63 5C028 FF16 HH14 5C040 FA01 FA02 GA03 GG08 KB28 MA03

Claims (1)

[Claims] 1. A composition formula _{(Ba 1-m Sr m)} i MgAl j
O _n: aluminate represented by _{Eu k (0 ≦ m ≦ 0.25,1} .
0 ≦ i ≦ 1.8, 12.7 ≦ j ≦ 21.0, 0.01 ≦ k ≦ 0.20, 21.0 ≦
A blue phosphor for a plasma display panel, comprising: n ≦ 34.5).