JPS61136580A - Preparation of phosphor - Google Patents

Abstract

PURPOSE:To obtain a blue light-emitting phosphor with prolonged after-grow for a color display tube with excellent luminance, by baking oxides of Sr, Ca, Mn and Sb, etc. with addition of a sulfate of K, Rb, Na or Cs as a flux. CONSTITUTION:Oxides of Sr, Ca, Mn and Sb, or compounds forming these oxides by heating are well mixed and then fired at about 1,100 deg.C. The fired product is crushed and then fired again at about 1,200 deg.C in O2 with addition of at least one comp. selected from among K2SO4, Rb2SO4, Na2SO4 and Cs2SO4 as a flux, to obtain a blue light-emitting phosphor of the formula (wherein 0<=x<=0.99; 0.01<=y<=0.25).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a long afterglow blue phosphor for color display tubes.

[Background of the invention]

With the spread of computers, the demand for color display tubes as input/output terminals is rapidly increasing.

Performance items required for color display tubes include:
These include higher-definition phosphor screens, increased display capacity, and improved focusing characteristics of electron guns. In order to increase the display capacity, it is necessary to increase the number of scanning lines and the horizontal (signal) frequency, but from a cost and technical standpoint, a method that lowers the frame frequency is usually used. It has been adopted. In this method, flicker (flickering of the screen) naturally becomes a problem when a short afterglow phosphor such as a phosphor for a color picture tube is used.

Therefore, three-color (red, green, and red phosphors) with long afterglow properties are required.

The afterglow characteristic is usually expressed as the 10% afterglow time (the time required for the emission intensity to decrease to 10% of the excitation level after the excitation by the Seiko beam is stopped), but as a phosphor for color display tubes, this is 10% to 200m5. (depending on frame frequency) is desirable.

Generally, color display tubes contain (Zn, Mg)3(PO4h: Mn (long afterglow red phosphor), Znz5io4: Mn, As
(long afterglow green phosphor) and Zrl:Ag (short afterglow blue phosphor). In addition, the above-mentioned ZnS
: Instead of Ag, Znz is used as a light blue component.
S i04: 1ldn, As, (zn, Mg
)s (PO+)z: A mixture of Mn and ZnS:Ag is used. As is clear from this, since the blue component has a short afterglow or is a mixture with different afterglow characteristics, flicker and color shift become a problem. In color display tubes, the functions of the three colors are fully demonstrated by using long-lasting phosphors.
#There is a strong desire to develop a single-component blue phosphor with long afterglow properties.

As a known blue phosphor, 5rSbzOs:Mn (Izv
est, Akad Nank 888几23 134
6 (19591), but its brightness is not very high.

[Purpose of the invention]

An object of the present invention is to provide a method for producing a long-lasting blue phosphor suitable for color display tubes.

[Summary of the invention]

The decay time constant of the luminescence of the long afterglow phosphor is at least several I
It is desirable that Q m s or more, but Mn is the only luminescent center that satisfies this. This luminescence varies widely from blue to red depending on the parent body. However, as a known blue phosphor, the above-mentioned 5rSbl Os: Mf
It's the only one. Therefore, we preliminarily synthesized the phosphor and investigated its luminescent properties. As a result, 1 of 1 light emission
0% afterglow time is approximately 35ms, emission peak position is 471
nm, and the chromaticity coordinates are X-0, 13, Y-0, 14.

Furthermore, when i9r is substituted with position 1&:ca in this phosphor, one emission color can be made into green, bluish-green, or green depending on the amount of substitution. As described above, it has desirable characteristics as a long afterglow blue phosphor, but its only drawback is low brightness. Therefore, in order to improve the brightness, we investigated various synthesis methods and found that alkali metal sulfates have a remarkable effect on improving brightness.

That is, the present invention is based on the general formula (8rs -x -y Ca z'Mny
) Sbz Os (however, Q <: , in a method for preparing a fluorescent material in which a compound capable of becoming an oxide of those elements is fired as a raw material, Km 804 , Rbz 8 as a flux
This is achieved by adding at least -at of Na2804, Na2804 and C5'2SO4.

Figure 1 shows (SraasCa (L23 Mno, os)
This figure shows the relationship between the amount of 2SO4 added to Sbz Os and the relative brightness. Note that the amount added is based on the above compositional formula. As is clear from the figure, K2804
When K28Ch is added at 30%, the amount is about 4 times as large as when K28Ch is not added. Although the fluxes other than K2 S04 are not shown, substantially the same effects as Kx 804 can be obtained.

Figure 2 shows (Sr as+tx Can Mnaos
) This shows the relationship between Ca substitution amount (X) and brightness in Sbz Os. Song +1jA is Km when Km 804 t-wt% is added, Song @B is! This is the case without 804 addition. Although the rate of increase in brightness varies depending on the amount of Ca substitution, it is clear that it increases significantly by adding KzSOa.

Fig. 3 Fi (Sr (L92-x Cam Mno,
os ) Sbz The relationship between the amount of Ca substitution and the chromaticity coordinate (Y value) is shown, and it can be seen that as the amount of Ca substitution increases, the emitted light color becomes greenish. Note that the X value of the chromaticity coordinate is almost unaffected by the amount of Ca substitution and is around 0.11.

[Embodiments of the invention]

Examples 1-5 8rCOs 1.358g 8bz Os 3.235gMn5O4II
Weigh out 0.1352 g of Ha0, mix well with an agate mortar, spread thinly on an alumina boat, and bake in air at 1100C for 30 minutes. This fired product was pulverized, the flux shown in the table below was added thereto, it was packed in an alumina crucible, and re-fired at 1200 C for 30 minutes in oxygen. After cooling, it was washed with water to remove flux. The phosphor obtained in this way.

When the brightness of a sample synthesized in the same manner without adding flux and having a composition of SrccezMno and osSbzOs was set to 1, the results shown in the table below were obtained.

Example 6 SrCOs 1018g CaCOs 0.230g8b20s
3.235gMn804・Hzo 0.1
Weigh out 352g, mix well with an agate pestle, spread it thinly on an alumina boat, and leave it in the air for 110 g.
Complete at 0C for 30 minutes. Crush this baked product and use it! 804 fe was added, the material was packed in an aluminum crucible, and refired at 1200G for 30 minutes in oxygen. The thus obtained phosphor has a composition of 8ra, a*Cao, z3Mno, oaSbzo6, and the brightness of this phosphor is set to the brightness t-1 of a sample synthesized in the same way without adding K2SO3.
It was the 38th.

〔Effect of the invention〕

As mentioned above, the method for manufacturing the long afterglow blue phosphor of the present invention: (Sr+-z-rcaxMny)Sbz06O brightness can be reduced by about 1.4 to λ4 compared to the conventional one (no flux added).
can be doubled to provide the desired phosphor for color display tubes.

[Brief explanation of drawings]

Figure 1 shows (S r (L69Ca o, zsMnao
a) A diagram showing the relationship between the amount of Kz804 added to 5b206 and relative brightness. Figure 2 shows (8ro, ez-+cCaxMnoAa)Sb
In the diagram showing the relationship between Ca substitution amount (X) and 4 degrees in zOs, curve A is the case when 2804 f: 40 times F is added and curve B is the case when Km 804 is not added. Figure 3 shows (Sro, ez-xcaxMnthos>8b
In zOs, the relationship between Ca +t[:l<x) and the chromaticity coordinate (Y if!E) is expressed as follows:

Claims (1)

[Claims] 1. General formula (Sr_1_-_x_-_yCa_xMn_y)Sb_
The phosphor represented by In the method for preparing a fluorescent material in which a compound capable of becoming an oxide of
A method for producing a phosphor, the method comprising adding at least one of O_4 and CS_2SO_4.