JPS6136038B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a phosphor suitable for use in index type color cathode ray tubes, flying spot tubes and the like.

For example, it is desirable that a phosphor for obtaining a beam index signal of an index-type color cathode ray tube have a brightness peak as high as possible and an afterglow time as short as possible. However, it is generally desired that the fluorescent material has a short afterglow time. Conversely, those with high brightness have a long afterglow time.

The present invention aims to provide a phosphor having a short afterglow time and a high brightness peak, that is, a high brightness peak/afterglow time ratio.

For example, cerium-activated yttrium-based phosphor,
For example, Y ₃ Al ₅ O _{12 :} Ce is known to have _a long life and _a relatively high brightness peak. Y ₃ Al ₃ Ga ₂ O ₁₂ :Ce substituted with Ga provides a relatively high brightness peak even though the afterglow time is shortened.

What contributes to the strength of the index signal is the P _H /γ value (where P _H is the relative peak intensity indicating the relative peak height in the afterglow curve of the phosphor, and γ is the decay time). Therefore, the cerium-activated yttrium aluminum gallium oxide phosphor described above is advantageous as a phosphor for obtaining an index signal.

The present invention provides a phosphor that can further improve the brightness peak in the phosphor of so-called cerium-activated yttrium aluminum gallium oxide such as Y ₃ Al ₃ Ga ₂ O ₁₂ :Ce described above. This is what we offer.

That is, in the present invention, a cerium-activated yttrium aluminum gallium oxide phosphor, for example, Y ₃ AlxGayO ₁₂ :Ce (where x+y=
5, in order to obtain x = 1 to 4, y = 4 to 1), a fluorine compound powder, for example, is added to the raw material powder.
1 to 50 mol %, more preferably 2.5 to 40 mol % of BaF ₂ is mixed with the raw material powder, and this is fired.

Examples of the present invention will be described below.

Example Raw material for Y ₃ Al ₃ Ga ₂ O ₁₂ :Ce phosphor having the following composition Y ₂ O ₃ 3/2×0.98 mol Al ₂ O ₃ 3/2 mol Ga ₂ O ₃ 1 mol CeO ₂ 3 0.1 mol of BaF ₂ is mixed in /2 x 0.02 mol, mixed in a ball mill using ethyl alcohol as a solvent, then dried at 80°C and calcined in air at 1550°C for 2 to 4 hours in an aluminum crucible with a lid. did.

The brightness peak of the phosphor obtained in this example is 100% the brightness peak of a phosphor obtained by firing without mixing the fluorine compound BaF ₂ , although it has the same composition as this example. When doing so, the relative brightness peak was 200%, and the brightness peak was significantly improved.

Although the phosphor according to this embodiment of the present invention was able to greatly improve its brightness peak, its afterglow time, that is, the time γ1/10 required for its luminance to decrease to 1/10, The afterglow time was 120 nsec when no compound was mixed, but it became 110 nsec according to the above-mentioned example of the present invention, and the afterglow time did not become longer, but rather became shorter. At the firing temperature, a fluorine compound, such as barium fluoride, acts as a flux and promotes the growth of the phosphor crystal, resulting in the formation of a phosphor crystal free of defects.

This defect causes a decrease in the amount of radiation (light) such as heat, or delays the radiation process and increases the afterglow time.

In the above-mentioned example, when the relative brightness peak and afterglow time γ were measured while changing the amount of BaF ₂ mixed, the results shown in FIGS. 1 and 2 were obtained. In FIGS. 1 and 2, the horizontal axis indicates the amount (mol %) of BaF ₂ added to the raw material of Y ₃ Al ₃ Ga ₂ O ₁₂ :Ce. As is clear from these measurement results, when the amount of BaF ₂ added is selected to be 1 to 50 mol%, preferably 2.5 to 40 mol%, a high brightness peak is obtained, and the afterglow time γ is It can be seen that the length can be kept shorter or the same as when _{the two} are not mixed.

In addition, in the above-mentioned example, Y ₃ A ₃ Ga ₂ O ₁₂ :
This is a case where BaF ₂ compound is mixed into the raw material of Ce phosphor, but Y ₃ Al ₂ Ga ₃ O ₁₂ :Ce, or
It was confirmed that the brightness peak could be improved even if each phosphor was obtained by mixing a BaF ₂ compound with each raw material of Y ₃ Al ₄ Ga′O ₁₂ :Ce or Y ₃ AlGa ₄ O ₁₂ :Ce. I met.

Further, it is also possible to use a pre-fired raw material for the phosphor, mix the BaF ₂ compound therein, and perform the above-mentioned firing.

In Figures 3 to 6, Al of Y ₃ AlxGayO ₁₂
Characteristics of each phosphor when 10 mol% of BaF ₂ is mixed and fired by changing the molar ratio x/y of Ga and Ga (solid line polarity) and when BaF ₂ is not mixed (dashed line curve) The measurement results are shown below. Figure 3 shows the attenuation characteristic curve (brightness-time characteristic) for each phosphor.
Fig. 4 shows the relative peak value P H of a similar attenuation characteristic curve, and Fig. 5 shows the relative peak value P _H of the same attenuation characteristic curve. Figure 6 shows the measurement result of the decay time γ1/10 until the brightness reaches 1/10 of the initial brightness.
This shows the calculation result of _H /γ.

As is clear from these figures 3 to 6, the phosphor having the garnet structure of yttrium aluminum gallium oxide containing Ga is
Compared to a garnet structure phosphor that does not contain P _H
can exhibit a high value and a small value of γ1/10, and the fluorescence becomes more pronounced by using _BaF2 .

As described above, according to the present invention in which BaF ₂ is used as a flux during firing of a phosphor having a Ga-containing garnet structure, it is possible to obtain a phosphor with a high P _H /γ, which is a characteristic value for evaluation of an index signal. I can do it. This fact is also supported by the fact that by mixing BaF ₂ during firing of the phosphor, a phosphor having a large grain size, a single phase, and excellent crystallinity can be obtained. Figures 7 to 11 are electron micrographs of each phosphor, and Figure 7 is a book obtained by baking Y ₃ Al ₃ Ga ₂ O ₁₂ :Ce with 10 mol% of BaF ₂ mixed in. A phosphor according to the invention, FIG.
Y ₃ Al ₃ Ga ₂ O ₁₂ : Ce sintered phosphor without mixing BaF ₂ , Figure 9 shows Y ₃ Al ₅ O ₁₂ : Ce which does not contain Ga.
3 is an electron micrograph of a phosphor obtained by mixing 10 mol% of BaF 2 with 10% of BaF ₂ and sintering it. In addition, Fig. 10 shows a phosphor obtained by adding another flux KF to Y ₃ Al ₃ Ga ₂ O ₁₂ :Ce containing Ga and sintering it, and Fig. 11 shows a similar Y ₃ Al ₃ Ga ₂ O ₁₂ phosphor. : Electron micrographs of sintered phosphors made by adding NH ₄ F/HF as a flux to Ce, each magnified 5000 times.

As is clear from comparing the 3000x photograph of Figure 7 with the other 3000x photographs of Figures 8 and 9 and 5000x Figures 10 and 11, the present invention shown in Figure 7 The phosphor has excellent crystallinity.

As mentioned above, the phosphor of the present invention has a short afterglow time and can increase its brightness peak, so it is suitable for use as a phosphor for index type color cathode ray tubes or flying spot tubes.

[Brief explanation of the drawing]

Figure 1 shows the Ba addition amount vs. relative brightness peak curve.
Figure 2 is Ba addition amount vs. afterglow time curve, Figure 3~
Figure 6 is a measurement curve diagram of each characteristic versus x/y _{of Y3AlxGayO12} :Ce with and without _BaF2 added, and Figures 7 to 11 are electron micrographs of various phosphors. It is.

Claims (1)

[Claims] 1 to a mixture of 1 Y ₂ O ₂ , Al ₂ O ₃ , Ga ₂ O ₃ , CeO ₂
Calcined with the addition of 50 mol% barium fluoride
Y ₃ AlxGayO ₁₂ :Ce (However, x+y=5, 1≦x
≦4, 1≦y≦4).