JPS5940869B2 - luminescent composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel luminescent composition that emits red light, and more particularly to a novel luminescent composition that emits high-intensity red light when excited by a slow electron beam.

BACKGROUND ART Conventionally, a zinc-activated zinc oxide phosphor, ZnOZn, has been known as a phosphor that emits light with high brightness by excitation with a slow electron beam. This phosphor can be obtained by firing zinc oxide (ZnO) in a reducing atmosphere or by adding a small amount of a zinc compound such as zinc sulfide (ZnS) to ZnO and firing it in air, and then exciting it with a slow electron beam. When exposed, it emits a high-intensity green-white color. For example, it is used as a phosphor for low-voltage excitation (low-speed electron beam excitation) fluorescent display tubes used as display elements in desktop computers, various measuring instruments, etc. ing. Other than this phosphor, there are almost no known phosphors that emit light with high brightness when excited by slow electron beams. The object of the present invention is to provide a phosphor other than ZnO and Zn that emits light with high brightness by excitation with a slow electron beam.

The present inventors have made various attempts on various phosphors with the aim of obtaining phosphors that emit high-intensity light by excitation with slow electron beams.

As a result, the europium-activated yttrium oxysulfide phosphor Y202S exhibits high-intensity red light emission under electron beam excitation with an accelerating voltage of several KV, but hardly emits light under low-speed electron beam excitation. EU, europium activated yttrium oxide phosphor Y203: Eu and europium activated yttrium vanadate phosphor YVO4:E
An appropriate amount of cadmium sulfide photoconductor (
They found that by adding and mixing CdS photoconductor, red light was emitted under low-speed electron beam excitation, which led them to the present invention. That is, the luminescent composition of the present invention comprises a Cd reading conductor, Y2O2S:Eu, Y2O3:EU and YVO4.
This is a mixed composition formed by mixing at least one of :Eu and Eu, and is characterized in that the mixing weight ratio of the two is in the range of 1:4 to 7:3. As the CdS photoconductor which is a component of the luminescent composition of the present invention, in addition to photoconductive CdS without Cu activation, CdS:Cu activated with Cu of lo-3y or less per 1 g of CdS is used.
can also be used. In this specification, including the claims, a CdS photoconductor is defined as a CdS photoconductor having a Cu activation amount of 1.
CdS having a value of 0-09/θ or less: This term includes both Cu and photoconductive CdS in which Cu is not activated. In particular, as a Cd bladder conductor, the Cu activation amount is 10-4.
By using CdS:Cu in the range of 9/9 to 5×10 g/9, a luminescent composition with high brightness can be obtained. The CdS photoconductor used in the luminescent composition of the present invention is produced by adding a predetermined amount of Cu to CdS raw powder obtained by chemically precipitating it with dichloromethane.
After adding and mixing copper as CuCl2・2H20 etc. (Cu
(This addition of Cu is unnecessary if photoconductive CdS is not activated), 400 to 6
Obtained by firing at a temperature of 00°C. At this time, it is more preferable to add CdCl2 as a fluxing agent in an amount of 6% by weight or less, since a photoconductor having a uniform particle size can be obtained. When the firing temperature is lower than 400°C, the obtained Cd
This is not preferred because the photoconductivity of the S photoconductor is insufficient. Furthermore, if the firing temperature is higher than 600°C, sintering will occur, which is not preferable. The other component of the luminescent composition of the present invention is Y2O2S:EU, . Y2O3:EU and YVO4:Eu are generally produced by the method described below.

First, Y2O2S:EU is a mixed rare earth oxide made by mixing yttrium oxide Y2O3 with a predetermined amount of europium oxide EU2O3, further 20 to 40% by weight of sulfur S, and 20 to 40% by weight of sodium carbonate Na2 as a flux.
Add and mix cO3 and heat to 1200 to 1300℃ in air.
It can be obtained by firing for 1 to 5 hours. This Y
2O2S: The amount of the preferred activator Eu for EU is the parent Y2O
2Sl9 to 1.5×10 9 , more preferably 5×10 to 6×10 9 .

Next, Y2O3:EU is a mixed rare earth oxide made by mixing Y2O3 with a predetermined amount of EU2O3, and 0.0% as a flux.
01 to 1 weight? boric acid H3BO3, potassium tetraborate K
Add and mix boron compounds such as 2B4O, and sodium tetraborate, Na2B4O7, and heat at 1300 to 1400°C in air.
It can be obtained by firing for 1 to 5 hours.

The preferred amount of the activator Eu in this Y2O3:EU is the base Y
It is 10-2 to 1.5×12109 with respect to 2O3l9, and more preferably 5×10 to 6×109.
Further, YVO4:Eu is obtained by adding and mixing vanadium pentoxide 205 in an equimolar amount to the mixed rare earth oxide to a mixed rare earth oxide formed by mixing a predetermined amount of EU2O3 with Y2O3,
It is obtained by firing in air at 1000 to 1100°C for 1 to 5 hours. The preferable amount of activator Eu for this YVO4:Eu is the base YVO4lf! -21 against
0 to 1.5×109, more preferably 7×10
-2 to 8×10 −2 g. In addition, in the above three types of phosphor manufacturing methods, the method for obtaining the mixed rare earth oxide consisting of Y2O3 and EU2O3 is simply Y2O3.
Although Y2O3 and EU2O3 may be physically mixed, in general, in order to improve their miscibility, Y2O3 and EU2O3 are once dissolved in nitric acid, and an oxalic acid aqueous solution is added thereto to dissolve yttrium oxalate and europium oxalate. A method has been adopted in which the co-precipitated rare earth oxalate is thermally decomposed to produce a mixed rare earth oxide. Y2O2S:EU, Y2O3:EU and YVO4 obtained by the above production method:
Eu emits high-intensity red light under electron beam excitation at an accelerating voltage of several k, and is used as a phosphor for the red light-emitting component of color television cathode ray tubes.

However, the luminescence of these phosphors under slow electron beam excitation is very weak, and especially under slow electron beam excitation with an accelerating voltage of 100 V or less, the brightness rapidly decreases and almost no light is emitted, making it impractical for practical use. I can't help it. The luminescent composition of the present invention is produced by adding a CdS photoconductor to a rare earth phosphor that is at least one of these Y2O2S:EUlY2O3:EU and YVO4:Eu, and then thoroughly milling the mixture in a mortar, ball mill, mixer mill, etc. It can be obtained by mixing.

Both are mixed in a weight ratio such that the CdS photoconductor/rare earth phosphor value ranges from 1/4 to 7/3. If the value of CdS photoconductor/rare earth phosphor is less than 1/4, the resulting composition will have properties close to those of a rare earth phosphor, will not emit light under slow electron beam excitation, and will not be of practical use. On the other hand, if the value of CdS photoconductor/rare earth phosphor is greater than 7/3, the resulting composition will emit very little light due to the small amount of rare earth phosphor and the strong coloring caused by the CdS photoconductor. However, it is still not practical. In terms of brightness, a more preferred value for the CdS photoconductor/rare earth phosphor is in the range of 13/20 to 3/2. FIG. 1 is a graph showing the relationship between the CdS photoconductor/rare earth phosphor value (weight ratio) and brightness of the luminescent composition of the present invention under slow electron beam excitation at a voltage of 80 V; The rare earth phosphors of B and C are Y2O2S:EUlY2O3:EU and YVO4:Eu, respectively, and the CdS photoconductors are both C
It is a graph when CdS:Cu has a u activation amount of 10 −4 g/9. As is clear from Figure 1, in both cases of rare earth phosphor, when the value of CdS photoconductor/rare earth phosphor is smaller than 1/4 or larger than 7/3, the brightness is extremely reduced. . In addition, in both cases of rare earth phosphor, the value of CdS photoconductor/rare earth phosphor is 13/20.
Luminescent compositions in the range of 3/2 to 3/2 have particularly high brightness.
Furthermore, as is clear from comparing Figure 1-A, B, and C,
If the value of CdS photoconductor/rare earth phosphor is constant,
The luminescent composition using Y2O2S:Eu (FIG. 1-A) exhibits the highest luminance. Although not shown in FIG. 1, the rare earth phosphors are Y2O2S:EU, . Y2O3:E
Similar results can be obtained when the CdS photoconductor/rare earth phosphor is composed of two or more of u and YVO4:Eu, and if the value of the CdS photoconductor/rare earth phosphor is in the range of 1/4 to 7/3, the present invention can be achieved. Needless to say, it is included in The luminescent composition of the present invention exhibits high-intensity red luminescence when excited by a slow electron beam. Figure 2 shows the relationship between accelerating voltage and brightness in the luminescent composition of the present invention (curve a), and the relationship between accelerating voltage and luminance in the rare earth phosphor alone (curve b), which is a component of the luminescent composition. This is shown for comparison, and A has a Cu activation amount of 1.
The luminescent composition of the present invention (curve a) obtained by mixing equal weight parts of CdS:Cu and Y2O2S:Eu, which are 09/9, and Y
2O2S: A graph showing the relationship between acceleration voltage and brightness for EU alone (curve b), B is a graph showing the relationship between acceleration voltage and brightness for EU alone (curve b), B is for Cu activation amount of 10-49/
The luminescent composition of the present invention (curve a) obtained by mixing equal weight parts of CdS:Cu and Y2O3:Eu, which is 9, and Y2O3:
A graph showing the relationship between acceleration voltage and brightness in EU alone (curve b) and C are Cd with Cu activation amount of 109/9
1 is a graph showing the relationship between accelerating voltage and brightness in a luminescent composition of the present invention prepared by mixing equal weight parts of S:Cu and YVO4:Eu (curve a) and YO4:EU alone (curve b). As is clear from FIG. 2, the luminescent composition of the present invention is
In the case of a rare earth phosphor alone, the brightness rapidly decreases and almost no light is emitted.Even under slow electron beam excitation at an accelerating voltage of 100 or less, it emits high-intensity red light.

For example, in Figure 1-A, B, and C, the acceleration voltage is 1.
Under low-speed electron beam excitation at 00V, the luminescent composition of the present invention (curve a) has luminance that is 1000 times or more higher than that of the rare earth phosphor alone (curve b), which is a component of the luminescent composition. . There are various possible reasons why these rare earth phosphors, which hardly emit light under slow electron beam excitation, emit light even under slow electron beam excitation by adding and mixing CdS photoconductors, but the main reasons are as follows. By adding and mixing the CdS photoconductor (the conductivity of the CdS photoconductor is improved by the emission of the rare earth phosphor), the conductivity of the entire composition is improved, resulting in a charge-up phenomenon upon excitation. It is thought that this is because the excitation efficiency is improved as the CdS photoconductor is eliminated and the excitation efficiency is improved. Figure 3 shows the emission spectrum of the luminescent composition of the present invention under slow electron beam excitation. B is the emission spectrum of the luminescent composition formed by mixing a CdS photoconductor and Y2O3:Eu, and C is the emission spectrum of the luminescent composition formed by CdS photoconductor and Y2O3:Eu.
This is an emission spectrum of a luminescent composition formed by mixing an S photoconductor and YVO4:Eu.

Figure 3 - Emission spectra of A, B and C are all Eu
It has a linear spectrum in the red region unique to 3+, and its emission color (emission chromaticity point) is only slightly different. Therefore, the rare earth phosphor which is one of the constituent components of the luminescent composition of the present invention is Y2O2S:EU1Y2O3:EU and YVO4:
Even if the luminescent composition is composed of two or more kinds of Eu, the luminescent color of the obtained luminescent composition is different from that of the rare earth phosphor when Y2O2S:EU, . Y
The luminescent color is almost the same as that of a luminescent composition composed of one of 2O3:EU and YVO4:Eu. The luminescent composition of the present invention is particularly useful as a phosphor for red-emitting fluorescent display tubes excited by slow electron beams.

For example, CdS photoconductor with Cu activation amount of 109/9 and Y2O2S:Eu with Eu activation amount of 5×109/fl.
A luminescent composition prepared by mixing equal parts of
09/9 CdS photoconductive growth and Eu activation amount is 5X10
A luminescent composition prepared by mixing equal weight parts of Y2O3:EU with a ratio of 9/9 and Cd with a Cu activation amount of 10-49/9.
YV whose S photoconductor Ju activation amount is 7×10-29/9
Approximately 5T of a luminescent composition prepared by mixing equal weight parts of O4 and Eu is placed on an aluminum substrate (anode plate).
When the anode plate voltage of each fluorescent display tube coated to a thickness of ny/~ is 80V1, the heater (cathode) voltage is 0.6V, and the heater current is 40mA, the luminance of each fluorescent display tube is 2.0ft-LlO. ．． 7ft-L and 1.0ft
-L level. The present invention will be explained below with reference to Examples.

Example 1 CdS:Cul weight part with Cu activation amount of 109/9 and Y2O2S:E with Eu activation amount of 5 x 10-29/9
A luminescent composition that emits high-intensity red light under low-speed electron beam excitation was obtained by thoroughly mixing the mixture and the weight parts of Ul using a mortar.

Similarly, luminescent compositions with different compositions could be obtained by varying the mixing weight ratio of both in the range of 1:4 to 7:3. Example 2 After CdS calcined at 500°C was thoroughly ground using a ball mill, the weight part of CdSl and the Eu activation amount were 5 x 10
By sufficiently mixing Y2O2S:Eul (9/9 parts by weight) using a mortar, a luminescent composition exhibiting high-intensity red light emission under low-speed electron beam excitation was obtained.

Similarly, luminescent compositions with different compositions could be obtained by varying the mixing weight ratio of both in the range of 1:4 to 7:3. Example 3 CdS:Cul weight part with Cu activation amount of 109/9 and Y2O3:EU with Eu activation amount of 5X10-29/9
1 part by weight was sufficiently mixed using a mortar to obtain a luminescent composition that emits high-intensity red light under low-speed electron beam excitation.

Similarly, luminescent compositions with different compositions could be obtained by varying the mixing weight ratio of both in the range of 1:4 to 7:3. Example 4 CdS:Ch1 weight part with Cu activation amount of 5 x 109/9 and YVO4:Eu with Eu activation amount of 7 x 109/9
1 part by weight was sufficiently mixed using a mortar to obtain a luminescent composition that emits high-intensity red light under low-speed electron beam excitation.

Similarly, luminescent compositions with different compositions could be obtained by varying the mixing weight ratio of both in the range of 1:4 to 7:3. Example 5 CdS:Cu2 weight part with Cu activation amount of 10g/9 and Y2O2S:E with Eu activation amount of 5 x 10-29/9
The weight part of ul and the amount of Eu activation are 5 x 10-2g/f! By sufficiently mixing Y2O3:EUl parts by weight in a mortar, a light-emitting composition that emits high-intensity red light under low-speed electron beam excitation was obtained.

Similarly, CdS: Cu and Y2O2S: EU and Y2O
3: Mixing weight ratio with rare earth phosphor consisting of Eu is 1:4.
By changing the ratio between 7:3 and 7:3, luminescent compositions with different compositions could be obtained.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the CdS photoconductor/rare earth phosphor value (weight ratio) and brightness of the luminescent composition of the present invention under slow electron beam excitation at an accelerating voltage of 80V;
and C are rare earth phosphors Y2O2S:EU, .
Y2O3:EU and YVO4:Eu, and both CdS photoconductors have a Cu activation amount of 109/fl (DCdS:
It is a graph in the case of Cu.

Claims (1)

[Claims] 1 Cadmium sulfide photoconductor CdS photoconductor and europium activated yttrium oxysulfide phosphor Y_2O_2S:
Eu, europium activated yttrium oxide phosphor Y_2O
A luminescent composition obtained by mixing Eu and at least one of europium-activated yttrium vanadate phosphor TVO_4:Eu in a weight ratio of 1:4 to 7:3.