JPS64999B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates primarily to a green-emitting phosphor used in the green-emitting phosphor surface of an electron tube, particularly a color cathode ray tube, and more particularly to a phosphor with improved light-emitting characteristics. Conventionally, copper-activated zinc cadmium sulfide, copper-activated zinc sulfide, copper-gold co-activated zinc sulfide, etc. have been used as green-emitting phosphors for color cathode ray tubes. Among these, copper-gold co-activated zinc sulfide phosphors have recently come into widespread use, as they are suitable for obtaining a relatively low-temperature white color, 6500〓+7 MPCD, and do not cause pollution problems because they do not contain cadmium. However, this copper-gold co-activated zinc sulfide phosphor contains gold in its composition, and the size of the gold ions is similar to that of the zinc ions that form the crystal lattice and the copper and aluminum ions that form the activator. It is extremely large in comparison and brings about various problems in light emission characteristics and manufacturing technology. For example, in the case of phosphors for color cathode ray tubes, a heat treatment process at approximately 400 to 500°C, that is, a baking process, is performed during the formation of the cathode ray tube. Compared to the initial characteristics, the body makes the luminescent color more bluish and lowers the luminance by several percent. The green-emitting fluorescent surface is an important material that determines the luminance color and brightness of color cathode ray tubes, and it is important that the brightness is even slightly superior, and changing the characteristics before and after baking treatment is important for quality stability. This is also undesirable from this point of view. This copper-gold co-activated zinc sulfide phosphor can be obtained by appropriately adding some flux to the raw material composition and firing at a high temperature of just under 1000°C, but this condition depends on the conditions for introducing gold. It's almost decided. Therefore, even if it is attempted to change the degree of growth of crystal grains, the conditions are limited, making control extremely difficult.
In particular, even if an attempt is made to obtain a crystal in which all the particles are uniformly and sufficiently grown, only a crystal with an unsatisfactory level of luminescent properties can be obtained, and a crystal that satisfies both properties at the same time cannot be obtained. Promoting crystal growth and improving the uniformity of growth improves the efficiency of the phosphor, improves the structure of the phosphor, and increases the brightness of the phosphor.
This will improve mechanical strength. Therefore, improving both characteristics is an important factor in preventing deterioration during the manufacturing process, and the fact that this is difficult to achieve is one of the obstacles to improving color cathode ray tube characteristics. It's summery. The object of the present invention is to eliminate these drawbacks and provide a green-emitting phosphor with further improved characteristics. That is, in this invention, a small amount of both cerium and erbium is added to the conventional copper-gold co-activated zinc sulfide phosphor composition, and the amount of addition is regulated as well as the activation amount, thereby making it possible to reduce the amount of cerium and erbium during the manufacturing process of color cathode ray tubes. It is a copper-gold co-activated zinc sulfide phosphor that does not cause baking deterioration and all particles grow uniformly and sufficiently to have improved characteristics. Examples of the present invention will be described in more detail below. Example 1 First, for 100 g of zinc sulfide, 0.07 g of copper sulfate (CuSO ₄ 5H ₂ O) and chloroauric acid (HAuC) were added.
0.04g of _{4.4H 2} O), aluminum nitrate (A
(NO ₃ ) ₃・9H ₂ O), 0.25 g of cerium nitrate (Ce
(NO ₃ ) _{3.6H 2} O) was weighed out, 0.08 g of a suitable flux such as ammonium iodide was added, and the mixture was calcined at 980° C. for 2 hours in a hydrogen sulfide atmosphere.
Thus 0.018% by weight copper, 0.019% by weight gold,
A green-emitting zinc sulfide phosphor containing 0.018% by weight of aluminum and further 0.01% by weight of cerium is obtained. The particles of this phosphor grow almost uniformly, exhibit a polyhedral shape with well-developed crystal faces, and have good transparency. The average particle size of these particles was approximately 10μ as evaluated by the Blaine method based on the aeration method. Next, the brightness after baking this phosphor powder at 450℃ for 90 minutes compared to before baking.
An increase of 1.5% was observed. In addition, this brightness evaluation was performed by irradiating the phosphor powder with an electron beam of 10KV and 1μA/cm ² and measuring the emitted light by receiving it with a photocell.It is expressed as a relative value to the standard value. be. In this example, the brightness after baking is improved compared to before baking, but some do not change at all before and after baking, some improve by about 0.5%, and others improve by nearly 1.5% as in this example. There are various things. This means that the phosphor of the present invention shows no essential change in efficiency as a result of the baking treatment. Rather, due to contamination during the phosphor treatment process or insufficient cleaning treatment, the surface of the phosphor particles is contaminated with impurities to varying degrees, and these impurities are removed by baking, resulting in varying brightness. You can consider doing so. Table 1 shows the luminance after baking and the average particle size of this example phosphor. However, the conventional example phosphor shown in the table was obtained in the same manner as the example phosphor except that cerium was not added, and therefore 0.018% by weight of copper,
It is a zinc sulfide green emitting phosphor activated with 0.019% gold and 0.018% aluminum by weight.

[Table] Optical micrographs of particle shapes are also shown. FIG. 1 shows an example, and FIG. 2 shows a conventional example. In the phosphor of the embodiment shown in FIG. 1, each crystal plane has grown more fully and has a polyhedral shape compared to the phosphor shown in FIG. 2, and the crystal transparency is improved. When this example phosphor is applied to an actual phosphor surface for a color cathode ray tube, it has excellent mechanical strength because the phosphor crystals have grown sufficiently, and when applied to the phosphor surface of a bead mill or the like prior to coating the phosphor surface. In the light dispersion process, brightness deterioration can be reduced and sufficient dispersion processing can be performed. In addition, it was observed that the shape characteristics of each particle were well aligned immediately after firing, and even though the particles were large, a dense fluorescent surface could be obtained, compared to conventional fluorescent surfaces. , it is possible to provide a fluorescent surface that is about 10% brighter. In this way, compared to conventional phosphors, this phosphor is a green-emitting phosphor with improved characteristics, less change during baking treatment, and stable quality.
Excellent for use on green-emitting fluorescent surfaces. Such an effect can be obtained by adding either cerium or erbium, or both, to the conventional copper-gold coactivated zinc sulfide phosphor. At that time, cerium and erbium may be added in the form of cerium compounds or erbium compounds such as cerium nitrate, erbium nitrate, cerium fluoride, erbium fluoride, cerium oxide, and erbium oxide. Also, even a very small amount is effective, so you can add a small amount, but if you add a large amount, the color of the phosphor's emission changes from red-green to green, and the amount added is 0.15% by weight.
When it exceeds the green luminescent material for color cathode ray tubes, it becomes unsuitable. This is because in this case, the luminescent color deviates from the preferred luminescent color that allows a relatively low-temperature white color of 6500〓+7 MPCD to be obtained. However, if the amount is 0.15% by weight or less, the change in luminescent color is within the range of manufacturing variations and does not pose a practical problem. The activation amount of copper, gold, and aluminum is not directly related to the amount of cerium and erbium, but is
0.001wt% to 0.10wt%, 0.005wt% to
Desirable brightness and emission color are exhibited in the range of 0.25% by weight, 0.005% by weight to 0.5% by weight. If the activation amount of copper or gold deviates from these ranges, either the brightness or the emitted color will deviate from the desired characteristics as a green component for a color cathode ray tube, and the current ratio or This causes problems in practical characteristics such as overall brightness. Further, in this embodiment, aluminum is used as a co-activator for copper and gold, but aluminum and chlorine may be used together or chlorine may be used alone. The activation amount of chlorine at this time is preferably 0.001% by weight to 0.05% by weight. Raw materials for these activators and co-activators include copper compounds such as copper sulfate (CuSO _{4.5H 2} O), gold compounds such as chloroauric acid (HAuC _{4.4H 2} O), aluminum nitrate (A(NO ₃ ) ₃・9H ₂ O),
Aluminum compounds such as aluminum sulfate (A ₂ (SO ₄ ) ₃・18H ₂ O), ammonium chloride (NH ₄ C)
), potassium chloride (KC), and other chlorine compounds may be selected and used. Also, alkali metals as fluxing agents,
It is sufficient to use a suitable combination of alkaline earth metal halides. Example 2 First, 100g of zinc sulfide, 0.063g of copper sulfate, chloroauric acid
0.063, 0.25 g of aluminum sulfate, 0.038 g of erbium oxide, 0.70 g of ammonium iodide, 0.1 g of rubidium iodide, and 1.5 g of sulfur. As a result, it is 0.016% by weight based on the total amount of phosphor.
A green-emitting zinc sulfide phosphor is obtained which is doped with copper, 0.03% by weight of gold, 0.02% by weight of aluminum and furthermore 0.03% by weight of erbium. This phosphor differs from a conventional copper-gold-activated zinc sulfide phosphor in that no erbium is added.The brightness after baking at 400°C for 2 hours is
Table 2 shows a comparison of the color cathode ray tube fluorescent film brightness and average particle size. From the table, it can be seen that the Example phosphor has good brightness after baking, has large particles, and is excellent in practical brightness characteristics.

[Table] The brightness after baking treatment was measured in the same manner as in the above example, and is shown as a relative value. The luminance of the fluorescent film was determined by drawing a raster of a certain area under a constant cathode current with a 25KV electron beam, measuring the luminance of the fluorescent film with a foot lamp part meter, and expressing it as a relative value. These evaluation methods are the same for the following examples. Example 3 First, 100g of zinc sulfide, 0.039g of copper sulfate, chloroauric acid
0.105g, potassium chloride 0.013g, cerium fluoride
0.028g of erbium sulfate, 0.053g of erbium sulfate, and 0.06g of ammonium chloride are thoroughly mixed and fired at 1000°C for 80 minutes in a hydrogen sulfide atmosphere. This results in 0.01 wt% copper, 0.05 wt% gold, 0.01 wt% chlorine,
A green-emitting zinc sulfide phosphor doped with 0.02% by weight of cerium and 0.02% by weight of erbium is obtained. This example phosphor differs from a conventional copper-gold activated zinc sulfide phosphor in that neither cerium nor erbium is added. Table 3 shows a comparison of the luminance of the fluorescent film and the average particle size.
The phosphor of the example has good brightness after baking treatment, has larger particles, and has excellent brightness characteristics in practical use.

[Table] Example 4 First, 100g of zinc sulfide, 0.031g of copper sulfate, chloroauric acid
Thoroughly mix each raw material of 0.032g, aluminum nitride 0.42g, cerium oxide 0.13g, ammonium iodide 0.1g, potassium iodide 0.1g, and sulfur 2g,
Bake at 980℃ for 60 minutes in a reducing sulfiding atmosphere.
This results in 0.008 wt% copper, 0.015 wt% gold,
A green-emitting zinc sulfide phosphor doped with 0.03% by weight aluminum and 0.10% by weight cerium is obtained. This example phosphor differs from a conventional copper-gold activated zinc sulfide phosphor in that cerium is not added. After baking at 400°C for 2 hours, the luminance, color cathode ray tube phosphor film luminance, and average Table 4 shows a comparison of particle sizes. The phosphor of the example has good brightness after baking treatment, has larger particles, and has excellent brightness characteristics in practical use.

【table】 [Brief explanation of the drawing]

FIG. 1 shows an optical micrograph of the present invention, and FIG. 2 shows a conventional green-emitting zinc sulfide phosphor.

Claims (1)

[Claims] 1 A green light-emitting phosphor that uses zinc sulfide as a matrix, uses aluminum or chlorine as a co-activator in addition to copper and gold, and contains at least one of cerium and erbium, where the content of copper and gold is less than the total amount of the phosphor. 0.001% to 0.10% by weight and
0.005% to 0.025% by weight, and the content of cerium and erbium is both greater than 0 and less than 0.15% by weight based on the total amount of the phosphor.