JPS5943507B2 - Method for manufacturing blue-emitting phosphor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a blue-emitting phosphor, and more particularly to a method for producing an alkaline earth metal aluminate phosphor activated with divalent europium.

Recently, gas discharge light-emitting devices have been actively developed in which a gas having a discharge emission spectrum in a wavelength region shorter than 200 nm, a phosphor, and a discharge electrode are sealed in a container.

This gas discharge light emitting element is used, for example, as a miniature light source in the form of a miniature lamp, or arranged in a matrix or segment form for display panels for characters, figures, and images. Conventionally, a fluorescent lamp is well known as a light source that excites a fluorescent substance to emit light using ultraviolet rays emitted by a gas discharge. This is caused by the discharge of mercury vapor.
Ultraviolet light of 53.7 nm is mainly emitted, and this ultraviolet light excites the phosphor to emit light. However, small lamp-shaped light sources and image display panels are characterized by the fact that the individual gas discharge light emitting elements are small, so the discharge gap is limited to about 2 to 3 mm or less. In this case, according to Patsien's law, which is well known in discharge physics, the pressure of the sealed gas needs to be quite high, from several tens to several hundreds of T0rr, but for example, at 15°C, it is less than 10''3T0rr, and even at 40°C, it is less than 10-2T0rr. Even if a mixed gas of mercury and argon gas is used, which provides only a saturated vapor pressure, the content ratio of mercury gas atoms is extremely low, and its radiation cannot be used effectively. Therefore, such a gas discharge light emitting device is usually filled with a rare gas that can easily obtain a pressure of several tens to several hundreds of tons at room temperature, or a suitable mixed gas such as hydrogen or nitrogen with this gas, and utilizes the discharge radiation. There were many cases where I did so.
The ultraviolet rays emitted by discharge in the single gas or mixed gas often have a strong emission spectrum in the so-called vacuum ultraviolet region, which is a wavelength region shorter than 200 nm. Conventional phosphors that emit blue light when excited by ultraviolet rays, cathode rays, or
Divalent europium-activated alkaline earth metal aluminate phosphor (BaO.6A!203:E
u2+, MgO-BaO,8Aノ,03:Eu2+,2
Mg0-BaO.7A1203:Eu2+ etc.) are well known.

However, this phosphor emits ultraviolet light emitted by a discharge of mercury vapor, that is, 253.7 nm (in the case of a low-pressure mercury lamp).
Alternatively, it is considered to be an excellent phosphor based on its emission characteristics under excitation of 365 nm (in the case of high-pressure mercury lamps).
The emission characteristics under vacuum ultraviolet excitation of 200 nm or less have not been investigated at all. In other words, the conventionally known phosphors have relatively high radiation efficiency (emission intensity/excitation intensity) under excitation of ultraviolet rays of 253.7 nm or 365 nm.
However, little is known about vacuum ultraviolet excitation in the wavelength region of 200 nm or less. According to experiments conducted by the present inventors, the compositional formula is AMg
O-BBaO-CAl2O3・DEuO (However, A, b,
When cl and d are respectively a+b+c+d=10, 0×a≦2.00, 0.25≦b≦2.00, 6.
The divalent europium-activated alkaline earth metal aluminate phosphor is a number that satisfies the following conditions: 0≦c≦8.5 and 0.05≦d≦0.30. It was found that the excitation also has a relatively high radiation efficiency.

The present inventors have developed a divalent europium-activated alkaline earth metal aluminate phosphor represented by the above composition formula.
Various experiments have been conducted regarding the manufacturing method for the purpose of further improving the radiation efficiency under vacuum ultraviolet excitation of 00 nm or less. As a result, it was discovered that when producing the above-mentioned phosphor, the radiation efficiency can be improved by using special additives and strictly specifying the firing conditions, and the above-mentioned object of the present invention has been achieved. The present invention particularly applies to 20
The present invention provides a method for producing a divalent europium-activated alkaline earth metal aluminate phosphor that has high radiation efficiency and high emission brightness under vacuum ultraviolet excitation of 0 nm or less.

According to experiments conducted by the present inventors, the divalent europium-activated alkaline earth metal aluminate fluorophore obtained by the production method of the present invention can be used not only under vacuum ultraviolet light excitation of 200 nm or less, but also under ultraviolet light excitation. It was found that the material also emitted high-intensity light under cathode ray or X-ray excitation. That is, the present invention provides a method for producing a divalent europium-activated alkaline earth metal aluminate phosphor that has high radiation efficiency and high luminance even under ultraviolet, cathode, or X-ray excitation. The manufacturing method of the present invention will be explained in detail below.

First, as a raw material for the phosphor, magnesium oxide (MgO) or carbonate, nitrate, sulfate, etc. can be easily used at high temperatures.
Barium oxide (Ba
O) or barium compounds that can be easily converted to BaO at high temperatures such as carbonates, nitrates, and sulfates; aluminum compounds that can be easily converted to Al2O3 at high temperatures such as aluminum oxide (Al2O3) or hydroxides, nitrates, and sulfates; europium oxide (EU2O3) or carbonate,
Europium compounds that can be easily converted to EU2O3 at high temperatures, such as nitrates and sulfates, are used.

Moreover, an alkali metal halide is used as an additive. That is, additives such as LiCl, NaCl, K
At least one of CI, NaF, KF, RbF and CsF is used. When all of the above-mentioned phosphor raw materials are converted into oxides (however, divalent oxides for europium), the composition formula is as follows: A, b, c and d are respectively a + b + c + d = 10. Time, 0
a≦2.00, 0.25≦b≦2.00, 6.0≦c
≦8.5 and 0.05≦d≦0.30), and then an appropriate amount of the above alkali metal halide additive is added and mixed to obtain The mixture is placed in a heat-resistant container such as a crucible and fired.

Firing is performed twice. That is, primary firing in air and secondary firing in a reducing atmosphere such as a nitrogen atmosphere containing, for example, 0.5 to 5% hydrogen. The firing temperature for the primary firing in air is suitably 1200°C to 1600°C. If the firing temperature is lower than 1200°C, the reaction will not be sufficiently promoted, and if it is higher than 1600°C, sintering will begin to occur, and in either case, a phosphor with high radiation efficiency and high luminance cannot be obtained. do not have. A more preferred firing temperature is 1300°C to 1500°C. The firing time varies depending on the firing temperature, filling amount, etc., but within the above firing temperature range, 30 minutes to 5 hours is appropriate. After the above-mentioned primary firing, the fired product is once pulverized and thoroughly mixed, and then filled into a heat-resistant container again and subjected to secondary firing in a reducing atmosphere. The firing temperature for the secondary firing is 1000°C to 1600°C, more preferably 1200°C to 150°C. If the firing temperature is lower than 1000°C, the reaction will not be sufficiently promoted, and if it is higher than 1600°C, sintering will begin to occur.
In either case, a phosphor with high radiation efficiency and high luminance cannot be obtained. The appropriate firing time is 30 minutes to 5 hours, same as the primary firing. By this secondary firing, trivalent europium is reduced to divalent europium. After firing, the fired product is washed with water, dried, passed through a sieve, and classified. In this way, particles with uniform particle diameters have high radiation efficiency under vacuum ultraviolet excitation of 200 nm or less, and high emission brightness.
It is possible to obtain a divalent europium-activated alkali metal aluminate phosphor whose composition formula is represented by A, b, c and d having the same definitions as above.

In the above description of the present invention, the alkali metal halide additive was added to and mixed with the phosphor raw material before the primary firing, but the timing of addition of the alkali metal halide additive is not limited to this. It may be added before firing, or it may be added both before primary firing and before secondary firing. That is, in the production method of the present invention, the alkali metal halide additive is added at least one of before primary firing and before secondary firing, but
There is a limit to the amount added at any time as described below. Figure 1 shows the amount of addition when the alkali metal halide additive in the production method of the present invention is NaF and the amount of addition of the obtained phosphor by vacuum ultraviolet rays of 200 nm or less (discharge with helium-xenon mixed gas). This is a graph showing the relationship between the emission brightness under excitation (emitted 147 nm bright line).

The amount of NaF added (horizontal axis) is calculated based on the composition formula (where A, b, c, and d are as above) when all of the raw materials for each phosphor are converted into oxides (however, divalent oxides for europium). weight for mixed oxides (with the same definition)? The luminance (vertical axis) is expressed as a relative value, with the luminance when no alkali metal halide is added as 100.

Note that point A on the vertical axis is a co-reducing atmosphere ( 211fi europium-activated alkaline earth metal aluminate phosphor, characterized in that the process is carried out in a nitrogen stream containing several percent hydrogen. Indicates the luminance of the light object. As is clear from FIG. 1, when the amount of NaF added is 20% by weight or less, a phosphor with higher luminance can be obtained than when no NaF is added. A more preferable addition amount range is 1 to 10% by weight, and an even more preferable addition amount range is 2 to 8% by weight. It is. In addition, Figure 1 shows the force D
This is a graph showing the relationship between the amount of addition and the luminance when NaF is used as the additive and the additive is added before primary firing. When two or more types of metal halides are used together, and when an alkali metal halide additive is added before secondary firing, or when added separately both before primary firing and before secondary firing, the amount of addition Regarding the relationship between luminance and power, results similar to those shown in Figure 1 were obtained. Based on the above, the amount of the alkali metal halide additive used in the production method of the present invention is determined based on the amount of the alkali metal halide additive used in the production method of the present invention.
The compositional formula is AMgO-B when converted to
It is not more than 20% by weight of the mixed oxide represented by BaO--CAl2O3.DEuO (where A, b, c and d have the same definitions as above).

A more preferable addition amount range is 1 to 10% by weight,
More preferably, it is 2 to 8% by weight. Table 1 below shows the phosphors obtained when the alkali metal halide additives used in the production method of the present invention are variously changed. 147 nm emission line)
It is a table showing luminescence brightness under excitation. The luminance is 10% the luminance when no alkali metal halide is added.
It is shown as a relative value set to 0. The composition of the phosphor in Table 1 above is MgO.0.8Ba0.8A1203.0.2Eu0, and the alkali metal halide additive is 5% by weight. was added before primary firing.

In addition, the primary firing was performed in air at 1500°C for 2 hours, and the secondary firing was performed at 1400°C in a nitrogen stream containing 5% hydrogen.
℃ for 2 hours. Note that the primary firing is performed in a reducing atmosphere (
When a phosphor was produced under exactly the same conditions as above, except that it was carried out in a nitrogen stream containing 5% hydrogen, the luminance was significantly reduced (10-30%). The reason for this is that, as shown in the excitation spectrum in Figure 2, the primary firing in air (curve a) is better than the primary firing in a reducing atmosphere (curve b). This is because the excitation efficiency in the vacuum ultraviolet region of 200 nm or less is far superior. As described above, in the production method of the present invention, it is an essential condition that the primary firing is performed in air, and if the atmosphere for the primary firing is made reducing like in the conventional method, the production method of the present invention can reduce the It is not possible to obtain a phosphor with high emission brightness and improved radiation efficiency under vacuum ultraviolet excitation of 200 nm or less as shown in FIG. As described below, according to the manufacturing method of the present invention, a high-brightness blue-emitting phosphor with improved radiation efficiency under vacuum ultraviolet excitation of 200 nm or less can be obtained. The thus obtained phosphor also exhibits high brightness and intense blue luminescence with improved radiation efficiency even under ultraviolet, cathode, or X-ray excitation.

That is, the phosphor obtained by the production method of the present invention is
Also when excited with 53.7 nm or 365 nm ultraviolet rays, cathode rays, or X-rays, the luminance was improved as shown in FIG. 1 and Table 1. The manufacturing method of the present invention not only improves the practicality of the 2gH europium-activated alkaline earth metal aluminate phosphor as a phosphor for gas discharge light emitting devices, but also improves the practicality of the 2gH europium-activated alkaline earth metal aluminate phosphor, as well as for low-pressure mercury lamps, high-pressure mercury lamps, cathode ray tubes, and X-ray tubes. The present invention has great industrial utility value as it improves its practicality as a phosphor for line image intensifier tubes and the like.

Next, the present invention will be explained with reference to Examples.

Example 1 The above-mentioned phosphor raw materials and additives were thoroughly mixed, and the resulting mixture was filled into a 501 aluminum crucible and fired in air at a temperature of 1500° C. for 2 hours.

After thoroughly pulverizing and mixing the fired product, it was again filled into an alumina crucible and fired at a temperature of 1300° C. for 2 hours in a nitrogen stream containing 2% hydrogen. After firing, the fired product was washed with water, dried, passed through a sieve, and classified. In this way, the particle size was uniform, and the composition formula was MgO・0.8Ba0・8A1203・
A divalent europium-activated alkaline earth metal aluminate phosphor represented by 0.2Eu0 was obtained. When this phosphor is excited by a 147 nm emission line emitted by a discharge in a helium-xenon mixed gas, it can be produced using the conventional manufacturing method (without using an alkali metal halide additive, by primary and secondary firing). The phosphor of the same composition obtained by the manufacturing method carried out in a co-reducing atmosphere (the same applies to Example 2 and below) exhibited blue light emission with a high brightness of 170%. In addition, this phosphor can be used for 253.7 nm or 365 nm ultraviolet rays,
When excited with cathode rays or X-rays, high-intensity blue light emission was also exhibited as in the case of vacuum ultraviolet ray excitation. Example 2 The above-mentioned phosphor raw materials and additives were thoroughly mixed, and the resulting mixture was filled into a 50 cc aluminum crucible and fired in air at a temperature of 1500° C. for 2 hours.

After thoroughly pulverizing and mixing the fired product, it was again filled into an alumina crucible and fired at a temperature of 1400° C. for 2 hours in a nitrogen stream containing 2% hydrogen. After firing, the fired product was washed with water, dried, passed through a sieve, and classified. In this way, the particle size was uniform, and the composition formula was MgO-0.93Ba0.8A1203
- A divalent europium-activated alkaline earth metal aluminate phosphor represented by 0.17Eu0 was obtained. When this phosphor is excited by a 147 nm emission line emitted by a discharge in a helium-xenon mixed gas, the phosphor of the same composition obtained by the conventional manufacturing method has a
% of high-intensity blue light emission. In addition, this phosphor is 25
When excited with 3.7 nm or 365 nm ultraviolet rays, cathode rays, or X-rays, high-intensity blue light emission was also exhibited as in the case of vacuum ultraviolet ray excitation. Example 3 The above-mentioned phosphor raw materials and additives were thoroughly mixed, and the resulting mixture was filled into a 50 cc aluminum crucible and fired in air at a temperature of 1400° C. for 2 hours.

After thoroughly pulverizing and mixing the fired product, it was again filled into an alumina crucible and fired at a temperature of 1400° C. for 2 hours in a nitrogen stream containing 2% hydrogen. After firing, the fired product was washed with water, dried, passed through a sieve, and classified. In this way, the particle size was uniform, and the composition formula was MgO-0.8Ba0.8A1203.
A divalent europium-activated alkaline earth metal aluminate phosphor represented by 0.2Eu0 was obtained. When this phosphor is excited by a 147 nm emission line emitted by a discharge in a helium-xenon mixed gas, it is 154% more active than a phosphor of the same composition obtained by conventional manufacturing methods. It showed high brightness blue light emission. This phosphor is 253.
7nm or 365nm ultraviolet rays, cathode rays or X
When excited by UV rays, high-intensity blue light emission was also exhibited as in the case of vacuum ultraviolet ray excitation. Example 4 Magnesium carbonate 4MgC03・Mg(0H)2 The above phosphor raw materials and additives were thoroughly mixed, the resulting mixture was filled into a 50CC alumina crucible, and the mixture was heated in air for 1 hour.
It was baked at a temperature of 400°C for 2 hours.

After thoroughly pulverizing and mixing the fired product, it was again filled into an alumina crucible and fired at a temperature of 1400° C. for 2 hours in a nitrogen stream containing 2% hydrogen. After firing, the fired product was washed with water, dried, passed through a sieve, and classified. In this way, the particle size is uniform, and its composition formula is 1.2Mg0-BaO・7.6A120
A divalent europium-activated alkaline earth metal aluminate phosphor represented by 3.0.2Eu0 was obtained. When this phosphor is excited by a 147 nm emission line emitted by a discharge in a helium-xenon mixed gas, the phosphor of the same composition obtained by the conventional manufacturing method has 156
% of high-intensity blue light emission. In addition, this phosphor is 25
When excited with 3.7 nm or 365 nm ultraviolet rays, cathode rays, or X-rays, high-intensity blue light emission was also exhibited as in the case of vacuum ultraviolet ray excitation.Example 5 Each of the above phosphor raw materials and additives was sufficiently added The resulting mixture was filled into a 50 cc aluminum crucible and fired in air at a temperature of 1300° C. for 3 hours.

Thoroughly crush the fired product, and then add sodium fluoride (NaF)
After adding 0.90f7 and mixing thoroughly, the aluminum crucible was filled again and heated to 1400 ml in a nitrogen stream containing 2% hydrogen.
Firing was carried out for 2 hours at a temperature of .degree. After firing, the fired product was washed with water, dried, passed through a sieve, and classified. In this way, a divalent europium-activated alkaline earth metal aluminate phosphor having a uniform particle size and having the composition formula was obtained.

When this phosphor is excited by a 147 nm bright line emitted by a discharge in a helium-xenon mixed gas, it is 165% as bright as a phosphor of the same composition obtained by conventional manufacturing methods. It showed high brightness blue light emission. Note that when this phosphor was excited with 253.7 nm or 365 nm ultraviolet rays, cathode rays, or X-rays, it also exhibited high-intensity blue light emission as in the case of vacuum ultraviolet ray excitation. Example 6 The above-mentioned phosphor raw materials and additives were thoroughly mixed, and the resulting mixture was filled into a 50 cc aluminum crucible and fired in air at a temperature of 1400° C. for 1.5 hours.

Thoroughly crush the fired product, and then add sodium fluoride (NaF)
After adding 0.90y and mixing thoroughly, the aluminum crucible was filled again and heated to 1500°C in a nitrogen stream containing 2% hydrogen.
Firing was carried out at a temperature of 1.5 hours. After firing, the fired product was washed with water, dried, passed through a sieve, and classified. In this way, a divalent europium-activated alkaline earth metal aluminate phosphor having a uniform particle size and having the composition formula was obtained.

When this phosphor is excited by a 147 nm emission line emitted by a discharge in a helium-xenon mixed gas, it is 180% more active than a phosphor of the same composition obtained by conventional manufacturing methods. It showed high brightness blue light emission. Note that when this phosphor was excited with 253.7 nm or 365 nm ultraviolet rays, cathode rays, or X-rays, it also exhibited high-intensity blue light emission as in the case of vacuum ultraviolet ray excitation. Example 7 Mixture 1 obtained by thoroughly mixing each of the above-mentioned materials for fire extinguisher! ,1
11. ．． ah? ? ＼． 1 BX. 4. J-11. fart? ---
―●Lei deception. Ka. I7”? 6, 2 It was fired at a temperature of 1300°C for 3 hours.

Thoroughly crush the baked product and reduce sodium iodide (Nal) to 2.1
41 was added and thoroughly mixed, the mixture was again filled into an alumina crucible and fired at a temperature of 1400° C. for 2 hours in a nitrogen stream containing 2% hydrogen. After firing, the fired product was washed with water, dried, passed through a sieve, and classified. In this way, a divalent europium-activated alkaline earth metal aluminate phosphor having a uniform particle size and having the composition formula was obtained.

When this phosphor is excited by a 147 nm emission line emitted by a discharge in a helium-xenon mixed gas, it is 162% of the phosphor of the same composition obtained by the conventional manufacturing method. It showed high brightness blue light emission. When this phosphor was excited with ultraviolet rays of 253.7 nm or 365 nm, cathode rays, or X-rays, it also emitted high-intensity blue light as in the case of vacuum ultraviolet ray excitation. Example
8 Thoroughly mix each of the above phosphor raw materials, and mix the resulting mixture with 50%
It was filled into a CC aluminum crucible and fired in air at a temperature of 1500°C for 1.5 hours.

Thoroughly crush the baked product to reduce potassium chloride (KC/l) to 1.9
After adding 0f and thoroughly mixing, the mixture was again filled into an alumina crucible and fired at a temperature of 1400° C. for 2 hours in a nitrogen stream containing 2% hydrogen. After firing, the fired product was washed with water, dried, passed through a sieve, and classified. In this way, a divalent europium-activated alkaline earth metal aluminate phosphor having a uniform particle size and having a composition formula represented by is obtained.

When this phosphor is excited by a 147 nm emission line emitted by a discharge in a helium-xenon gas mixture, it has a 155% increase in brightness compared to a phosphor of the same composition obtained by conventional manufacturing methods. It showed bright blue emission. Note that when this phosphor was excited with 253.7 nm or 365 nm ultraviolet rays, cathode rays, or X-rays, it also exhibited high-intensity blue light emission as in the case of vacuum ultraviolet ray excitation.

[Brief explanation of drawings]

FIG. 1 is a graph illustrating the relationship between the amount of alkali metal halide added and the luminance of the obtained phosphor under vacuum ultraviolet excitation at 200 nm or less in the production method of the present invention.

Claims (1)

[Claims] 1 Magnesium oxide (MgO) or a magnesium compound that can be easily converted to MgO at high temperatures, barium oxide (BaO) or a barium compound that can be easily converted to BaO at high temperatures, aluminum oxide (Al_2O_3) or easily converted to BaO at high temperatures. Aluminum compounds and europium oxide (Eu_2O_3) that can be converted into Al_2O_3
) or europium compounds that can be easily converted to Eu_2O_3 at high temperatures, when all of these are converted into oxides (however, europium is a divalent oxide), the composition formula is aMgO・bBaO・cAl_2O_3・d
EuO (however, a, b, c and d are a+b+c, respectively)
When +d=10, 0<a≦2.00, 0.25≦
b≦2.00, 6.0≦c≦8.5 and 0.05≦d
This is a number that satisfies the condition of ≦0.30. ) and mix it in the air at 1200
The composition formula 1. A method for producing a divalent europium-activated alkaline earth metal aluminate blue-emitting phosphor, which comprises adding an alkali metal halide in an amount of 20% or less by weight of a mixed oxide represented by: 2 The amount of the alkali metal halide added is 1 to 1
A method for producing a blue-emitting divalent europium-activated alkaline earth metal aluminate phosphor according to claim 1, wherein the amount is 0% by weight. 3 The amount of the alkali metal halide added is 2 to 8
% by weight. A method for producing a divalent europium-activated alkaline earth metal aluminate blue-emitting phosphor according to claim 2. 4 The primary firing temperature and secondary firing temperature are each 130
Divalent europium-activated alkaline earth metal aluminate blue-emitting fluorescence according to any one of claims 1 to 3, characterized in that the temperature is 0°C to 1500°C and 1200°C to 1500°C. How the body is manufactured.