JPS6166785A - Fluorescent substance - Google Patents

Abstract

PURPOSE:A red fluorescent substance excitable with electron beams that is obtained by activating Y2O3:Eu with Tb or Pr at a specific ratio, thus showing good current-brightness saturation properties. CONSTITUTION:The objective fluorescent substance is obtained by activating Y2O3:Eu with less than 500X10<-6>mol of Tb or Pr (where 0mol is excluded). The objective fluorescent substance is obtained by subjecting a starting mixture containing Y2O3 and others to first calcination in air at 1,500 deg.C for 2hr, then second calcination in a gas atmosphere containing 4% H2 and 96% Ar at 1,000 deg.C for 4hr. Then, they are a little loosened and washed with 3% HNO3 aqueous solution to remove remaining flux and rinsed with water.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a phosphor, particularly an electron beam excited red phosphor Y2O3:
This invention relates to improving the current brightness saturation characteristics of Eu.

[Conventional technology]

Y2O2S:Eu is used as the red color of the electron beam excited phosphor in ordinary color cathode ray tubes. Furthermore, a phosphor in which Tb is added to Y2O2S:Eu has also been proposed (Japanese Patent Publication No. 47-13243). However, in the case of color cathode ray tubes used in high current density regions such as projector tubes, brightness saturation becomes a problem, and Y2O3:Eu, which has excellent brightness saturation characteristics as a red phosphor,
has been used.

[Problem that the invention seeks to solve]

However, in order to realize a brighter and more compact projector tube, it is necessary to excite the phosphor in a higher current density range. Further, improvements have been made to the electron gun to improve the resolution of the projector tube, and the spot diameter of the electron beam, that is, the spot characteristics, has also been improved, and the diameter has been reduced by 60%. In other words, the area is approximately 17
6, which means that the instantaneous current density (cathode current/spot area) has increased approximately six times. This improvement in the spot characteristics of the electron gun is equivalent to an increase in the excitation current density for the phosphor. For this reason, Y2O3 has traditionally been said to have excellent brightness saturation characteristics: ! ! There is also a need for improvement in u.

In view of the above-mentioned points, the present invention provides a red phosphor with better brightness saturation characteristics.

[Means for solving problems]

In the present invention, 500% of Tb or Pr is added to V2O3: Eu.
X 10'mol or less, preferably 200 X 10''8
A red phosphor is formed by co-activation in a mole or less range (excluding 0 mole).

[Effect]

FIG. 1 is a current brightness characteristic curve diagram of a phosphor in which Y2O3:Eu is coactivated, and FIG. 2 is a current brightness characteristic curve diagram of a phosphor in which V2O3:Eu is coactivated with Pr. Each figure uses the concentration of TbSPr as a parameter, as will be described later.The vertical axis shows the brightness and the horizontal axis shows the current density.As is clear from these characteristic curves, Tb or Pr is
If 10'mol or less of X is added, unadded Y2
O3: I! Compared to u, the brightness in the high current density region is high, and the current brightness saturation characteristics are improved. When the addition of Tb or Pr exceeds 500 x 10' moles, conventional Y2O3
: No significant effect can be obtained compared to Eu.

[Example] The phosphor of the present invention has the general formula (1-x) Y2O3: 2xBu, 2yM However,
M is a rare earth element consisting of Tb or Pr 0.02≦2x≦
It is composed of the following: 0.10 0ku2y≦5X 10-4.

In this example, in the above phosphor, 2χ-0,0365
Regarding the phosphor when ゜2y=5X10″S,
It will be explained in detail along with its manufacturing method.

Composition'/203 (purity 99.99%) 108
．． 79gF! u203 (purity 99.99%) 6
．． 42gTb◆07 (purity 99.99%) 0.
0094gBaF2 (purity reagent special grade) 17.5
3 g of the above raw material is placed in a polyethylene container (11) together with 100 cc of ethanol, mixed by rotation at a rotational speed of 60 to 1100 rpm, and then filtered and dried to obtain a starting material for calcination. Note that other alkaline earth or alkali metal halides are also effective as the flux.

Also, the amount of flux in the example is '/203 @ Eu
Although the amount is 20 mol % relative to 1 mol, the effect can be obtained even at 1 mol % to 40 mol %.

Next, the synthesis of Y2O3:εU, which enters the firing process, is carried out in air at 1400° C. to 1500° C. for 2 to 6 hours. That is, the main process is heat treatment to replace Euj+ with Y3÷. However, in the case of the present invention, for example, Tb is added, so obtaining a high-brightness phosphor cannot be achieved by just one firing. Tb is commercially available in the form of tb+Ot. The valence of this Tb ion is between 3 and 4 and must be reduced in order to replace it with Y3+.

Therefore, in the present invention, first, the above-mentioned starting material for calcination is subjected to a first calcination in air at 1500° C. for 2 hours, and at this time, an alumina crucible with a lid is used as the crucible. In order to increase the flux effect, the crucible body and lid were bonded together using, for example, Aron Ceramic D (trade name) manufactured by Toagosei.

Next, a second firing is performed at 1000° C. for 4 hours in a gas atmosphere consisting of 4% H2 and 96% Ar.

At this time, use a crucible without a lid.

The body color of the sample after the first firing is slightly yellowish. This indicates that Tb in the raw material was not completely substituted with Y. Since the sample after the 21st firing was fired in a reducing atmosphere, the body color was also white, indicating that Tb was completely replaced with Y.

The relative brightness of the sample after the first firing was also 100 when excited by electron beam.
%, the improvement was 111% after the second firing. The reason for this is that when examining the residual flux, the amount of Ba'' in 1 g of the sample was determined to be 103 μ/g after the first firing.
, after the second firing, it was 99 .mu./g, and since it was almost the same after the first firing and after the second firing, it is thought that this is due to the degree of substitution of Tb with Y. In this way, T
When b is added, firing in a reducing atmosphere becomes necessary.

Next, a cleaning step is performed to remove the residual flux BaF2. That is, after firing, the sample was loosened slightly and 3% HNO3
The solution was stirred with a stirrer (rotation speed 100 rpm+) for 60 minutes, and then washed with water to remove BaF2. In this case, 3% HNO3 solution is stirred at a rate of 5 Qcc per 4 g of the sample phosphor. Note that if the acid concentration during cleaning is too high, the base Y2O3:Eu and Tb themselves will be dissolved.The best concentration is around 3%, and even this will dissolve about 1 to 2% of the base surface by weight. However, it actually has the effect of removing the non-emissive layer on the surface. When the relative brightness and amount of residual flux after cleaning are expressed as Ba'', the relative brightness is 100% and the amount of BaO is 99% before cleaning.
The relative brightness is 111r/g, but after cleaning the relative brightness is 110%.
, the amount of Ba''+ is 2■/g.

In this way, the desired Y20*: Flu, Tb is obtained.

Note that ')'203: Eu and Pr can be obtained by going through the same process using 0.00851 g of PrgOsl (purity 99.99%) in place of the above-mentioned composition ':CTb+Ov.

Figure 1 shows '/2 according to the present invention obtained in this way.
03: In Bu and Tb phosphors, the Tb concentration is 50X 104 mol (curve x mark) and 100
XIO″6 mol (curve △ mark), 200 X 10’
Mol (curve mark), 500 x 101 mole (curve ◇ mark)
, 100OX 10-'mol (curve ○ mark) and 1500
The current brightness characteristic curves when changing the current brightness characteristic curve to
Compare it with the one (curve/mark) and post it.

FIG. 2 similarly shows Y203: lEu according to the present invention.
+ In the phosphor of Pr, increase the concentration of Pr by 50×
1 inch mole (curve x mark), 100 XIO"G mole (Ell to curve), 200 x 10"6 mole (curve mark)
, 500 x 1 inch mole (curve ◇ mark), 100OX
The brightness characteristic curves of each type and flow when changing to 10 (mole (curve O mark)) and 1500 x 10' mole (curve mark M),
A comparison is shown with that of conventional '1xox:Eu without Pr addition (curve/mark).

The measurements of the characteristics shown in FIGS. 1 and 2 were carried out using the respective phosphors in an 8-inch projector tube at an excitation voltage of 30 KV. The vertical axis shows the brightness, and the horizontal axis shows the current density, which is the value obtained by dividing the cathode current by the raster size.

As is clear from Figures 1 and 2, '/203:
lEu, Tb and V203: For both Flu + Pr, if the concentration of Tb or Pr is 500X10''6 mol or less (however, 0 mol is not included), the conventionally used Y2O3: [higher current compared to Eu The brightness in the density region is higher and the brightness saturation characteristics are better.
The Tb concentration in the figure is 50 × 1 mmol (curve × mark) and 100
X 10'mol (curve Δ mark) added'/lox:
Looking at Eu and Tb phosphors, these are conventional '
/203: Compared to Flu (curve/mark), it has the same brightness in the low current density region, but it has the same brightness in the high current density region (100
μA/-), the brightness increases by more than 20%, and the difference widens in the high current density region.If we calculate the γ value that determines the current brightness saturation characteristic from this characteristic, at Tb-0, r -0, At 78°Tb-50x104 moles, γ-0,
82,, Tb-100x 10'mol γ-0,85
Therefore, the current brightness saturation characteristics are improved by adding dichloromethane.

〔Effect of the invention〕

- According to the present invention described above, 500 x 10 of Tb or Pr is added to Y2O3:Eu, which is an electron beam excited red phosphor.
By co-activating in the range of -' molar or less, the brightness in the high current density region is further improved and the current brightness saturation characteristics are improved. Therefore, the red phosphor according to the present invention is suitable for application to a red phosphor for a projector tube used in a high current density region, for example.

[Brief explanation of drawings]

FIG. 1 is a current brightness characteristic curve diagram of a phosphor in which Y2O3: Flu and Tb are coactivated according to the present invention, and FIG. 2 is a current brightness characteristic curve of a phosphor in which Y2O3: Hu and Pr are coactivated according to the present invention. It is a characteristic curve diagram.

Claims (1)

[Claims] Y_2O_3: 500×10^ of Tb or Pr in Eu
- A phosphor formed by coactivation in a range of 6 moles or less (excluding 0 moles).