JPS58115024A - Zinc sulfide fluorescent substance - Google Patents

Abstract

PURPOSE:A long afterglow fluorescent substance, emitting light of blue color, obtained by using ZnS as a parent material, Ag as an activator and In as the first co-activator and at least one of Cl, Br, I, F and Al as the second co-activator, and usable for cathode-ray tubes of high resolution. CONSTITUTION:In preparing a long afterglow fluorescent substance emitting light of blue color, and suitable for use in cathode-ray tubes of high resolution, the following substances are weighed in amounts based on the weight of ZnS powder as a parent material: 5X10<-4>-10<-1>wt% silver nitrate, silver sulfide, etc. as a raw material for an activator Ag, 10<-6>-10<-1>wt% indium nitrate, indium sulfide, etc. as a raw material for the first co-activator and 5X10<-6>-5X10<-2>wt% at least one of chlorides, bromides, iodides, fluorides of alkali metals, etc. or aluminum compounds as a raw material for the second co-activator. The resultant substances are then ground and mixed in a ball mill, etc. to give a mixture of the raw materials for a fluorescent substance. The resultant mixture is then calcined in a quartz crucible at 600-1,050 deg.C for 0.5-7hr to afford the aimed fluorescent substance.

Description

[Detailed description of the invention] Awesome about the body.

It is desired to use high-resolution cathode ray tubes for terminal display devices in computers that display detailed characters and graphics, display devices for aircraft control systems, and the like. It is known that one effective method for improving the resolution of cathode ray tubes is to make the scanning speed of the fluorescent film by electron beams two to three times slower than that of cathode ray tubes for ordinary display devices. The phosphor that makes up the phosphor film of a high-resolution cathode ray tube has an afterglow time of 10 seconds (the time required for the luminance to drop to 10% of the excitation level after excitation stops), which is the phosphor film of a normal display cathode ray tube. It is necessary that the length be several tens to hundreds of times longer than the phosphor constituting the phosphor.

Conventionally, a manganese- and arsenic-activated zinc silicate green-emitting phosphor (Zn 2 S 10 4 :Mn #8
), manganese-activated potassium fluoride orange-emitting phosphor (KMgF3: Mn), lead- and manganese-activated calcium silicate orange-emitting phosphor (easioa)
: Pb, Mn), manganese-activated fluoride mag, nesium red-emitting phosphor (MgF2:Mn), manganese-activated zinc/magnesium orthophosphate red-emitting phosphor C (
Zn, Mg)3(PO4)2:Mn, ), etc. are known, but there is no known blue-emitting phosphor with long afterglow that can be used in the above-mentioned high-resolution cathode ray tube. As is well known, a blue-emitting phosphor is necessary to obtain black-and-white cathode ray tubes and color cathode ray tubes, and from this point of view, a blue-emitting phosphor with long afterglow that can be used in the above-mentioned high-resolution cathode ray tubes has been developed. desired.

In view of the above request, silver, which is used in cathode ray tubes for black and white televisions, cathode ray tubes for color television, etc., is used as an activator, and at least one of chlorine, bromine, iodine, fluorine and aluminum is used as a co-activator. A short afterglow W color luminescent zinc sulfide phosphor (ZnS: Ag,
, where X is at least one of chlorine, bromine, iodine, fluorine, and aluminum) and the above-mentioned long-afterglow green-emitting phosphor and red-emitting phosphor are mixed in a specific ratio, and this mixture Fluorescent material (called light pull fluorescent material)
It has been proposed to use this material as a blue-emitting phosphor constituting the fluorescent film of the high-resolution cathode ray tube to make the human eye feel as if the blue light has an afterglow. However, the above mixed phosphor is ZnS:Ag,
Because the phosphor has a very short afterglow time of several hundred to several hundred microseconds, a color shift occurs in the emitted light color after excitation is stopped.
Furthermore, since it is a mixture of phosphors that emit light of different colors, color unevenness tends to occur in the emitted light, and the color purity of the emitted color (blue) is also poor.

As mentioned above, no long-afterglow blue-emitting phosphor that can be used in the above-mentioned high-resolution cathode ray tubes has been known, and this is a major cause of inhibiting the spread of high-resolution cathode ray tubes.

The present invention was made under the above-mentioned circumstances, and provides a long afterglow blue-emitting phosphor, particularly a long afterglow material suitable for use in high resolution cathode ray tubes. The purpose of the present invention is to provide a blue-emitting phosphor.

In order to achieve the above object, the present inventors have conducted various studies on converting the ZnS:Ag, I've done it.

As a result, when activating zinc sulfide with an appropriate amount of indium along with an appropriate amount of silver and X (X being at least one of chlorine, bromine, iodine, fluorine, and aluminum), Zns:Ag, It has been found that it is possible to obtain a blue-emitting phosphor that has a significantly longer afterglow time by 10% than the X phosphor. This long afterglow ZnS: Agy
In the I n +X blue-emitting phosphor, indium also affects the luminance, and as the amount of indium activation increases, the luminance of the phosphor decreases. Of course ZnS
:Ag, In,
, In, and X phosphors have been studied to increase their luminance. As a result, when raw zinc sulfide powder containing a large amount of sulfur during refining is used as a base material and a small amount of sulfur is included in the resulting phosphor, it has little effect on the afterglow properties. We have found that the decrease in luminance caused by activating indium can be significantly suppressed.

The present invention has been made based on the above findings. That is, the uninvented long-afterglow blue-emitting phosphor is made of zinc sulfide as the matrix, silver as the activator, and indium as the primary material.
as a co-activator, and at least one of chlorine, bromine, iodine, fluorine and aluminum as a second co-activator,
The amounts of the activator, the first co-activator and the second co-activator are 5 x 10'-' to 10-1% by weight and 1O-6 to 10-6% by weight of the zinc sulfide matrix, respectively; and sulfur in an amount of 10-5 to 8 x 10-'% by weight of the zinc sulfide matrix.
It is characterized by containing.

The above blue-emitting zinc sulfide phosphor of the present invention is a conventional ZnS phosphor.
: Ag, The phosphor of the present invention has a cubic or hexagonal crystal phase as its main crystal phase depending on the firing temperature during production, but phosphors with a cubic system as its main crystal phase tend to have a hexagonal crystal phase. The former is 10% more luminescent than the latter in the indium activation amount range that provides a phosphor with higher luminance and higher emission color purity than the phosphor with the main crystal phase.
Long afterglow time. From this point of view, among the phosphors of the present invention, a phosphor having a cubic crystal system as its main crystal phase is more suitable for use as a blue-emitting phosphor for high-resolution cathode ray tubes than a phosphor having a hexagonal system as its main crystal phase. It is more preferable as

Note that the values of the 10% afterglow time described in this specification are all values when the current density of the stimulating electron beam is 1 μm.

The present invention will be explained in detail below.

The phosphor of the present invention is manufactured by the manufacturing method described below.

First, the raw materials for the phosphor are 1) raw zinc sulfide powder containing a large amount of sulfur during refining (base material and raw material for sulfur); 11) silver compounds such as silver nitrate, silver sulfide, and silver chloride (
activator raw material) 111) Indium compounds such as indium nitrate, indium sulfide, and indium chloride (first coactivator raw material), and iv) alkali metals (Na, K, Li%Rb and Cs) and Alkaline earth metals (Ca, Mg.

At least one compound selected from the group consisting of chlorides, bromides, iodides, and fluorides (Sr, Zn, Cd, and Ba), and aluminum compounds such as aluminum nitrate, aluminum sulfate, aluminum oxide, and aluminum halides ( Second co-activator raw material) is used. The base material and sulfur' raw material in I) above can be prepared, for example, by adding ammonium sulfide to a weakly acidic zinc sulfate aqueous solution with a pH of 6 to 40 while maintaining the pH value of the aqueous solution to precipitate zinc sulfide. . The amount of sulfur other than the stoichiometric amount contained in the zinc sulfide raw powder prepared in this way depends on the pH value of the aqueous solution at the time of precipitate formation, and the lower the pH value (that is, the higher the acidity) The amount will increase. In general, raw zinc sulfide powder precipitated from an aqueous solution with a pH of 6 to 4 contains sulfur in an amount other than the stoichiometric amount, ranging from a few tenths of a percent to several tens of percent by weight of zinc sulfide. Most of the sulfur contained in the raw zinc sulfide powder other than the stoichiometric amount is lost during firing, and only a small portion remains in the resulting phosphor. Therefore, the zinc sulfide raw powder mentioned above, which is both the base material and the raw material for the trace amount of sulfur contained in the obtained phosphor, is A material containing sulfur in an amount other than the stoichiometric amount that can achieve the desired sulfur content, which is selected from the range of 10-5 to s x io = "wt% of the zinc sulfide matrix, is used.

The base material and sulfur raw material in I) above, the activator raw material in ++) and the first co-activator raw material in 111) are the same as the amount of silver in the activator raw material in 11) and the first co-activator raw material in 111). The amount of indium in the co-activator raw material is the sulfide contained in the matrix () and the sulfur raw material, respectively. The amount used is such that the amount of zinc is 5 x 10-' to 10-1% by weight and 10-6 to 10-1% by weight. In addition, the second coactivator raw material in iV) is chlorine, bromine, etc. contained in the obtained phosphor.
The amount of at least one of iodine, fluorine and aluminum (i.e. the amount of the second co-activator) is used in an amount such that the amount is 5 x 10' to 5 x 10-2% by weight of the zinc sulfide matrix. . That is, the aluminum in the second co-activator raw material remains in the phosphor containing silver and becomes the second co-activator, while the halogen in the second co-activator raw material remains in the phosphor. Most of it is lost during firing, and only a small portion remains in the resulting phosphor. Therefore, the above alkali metal or alkaline earth metal halides, which are raw materials for halogen, contain tens to hundreds of times the desired amount of halogen activation, depending on the firing temperature, etc. l used. In addition, when silver halide is used as a raw material for the activator silver, when indium halide is used as a raw material for the first co-activator indium, or when aluminum halide is used as a raw material for aluminum, Some of the necessary halogen is also provided by these raw materials.

The alkali metal or alkaline earth metal halide acts both as a halogen donor and as a flux.

Required amounts of the above four phosphor raw materials are weighed out and thoroughly mixed using a grinding mixer such as a ball mill or a mixer mill to obtain a phosphor raw material mixture.

Note that this phosphor raw material is mixed with the above matrix and sulfur raw materials, the above 11) activator raw material, 111) the first coactivator raw material, and iv) the second coactivator raw material. It may also be carried out in a wet manner by adding as a solution. In this case, the phosphor raw material mixture obtained after mixing is sufficiently dried.

Next, the barreled phosphor raw material mixture is filled into a heat-resistant container such as a quartz crucible or a quartz tube, and fired. Firing is performed in a sulfidic atmosphere such as a hydrogen sulfide atmosphere, a sulfur vapor atmosphere, or a carbon disulfide atmosphere. Firing temperature is 600 to 120
0°C is appropriate. When the firing temperature is higher than 1050°C, a phosphor having a hexagonal system as the main crystal phase is obtained;
On the other hand, when the firing temperature is 1050°C or less, a phosphor having a cubic crystal system as the main crystal phase can be obtained. That is, the phosphor of the present invention has a phase transition point around 1050°C. As will be explained later, a phosphor having a cubic crystal system as its main crystal phase is more preferable as a blue-emitting phosphor for a high-resolution cathode ray tube than a phosphor having a hexagonal system as its main crystal phase. . Therefore, the firing temperature is preferably 600 to 1050°C, more preferably 800 to 1050°C.
It is °C. The firing time varies depending on the firing temperature used, the amount of the phosphor raw material mixture filled in the heat-resistant container, etc., but in the above firing temperature range, 0.5 to 7 hours is appropriate. After firing, the obtained fired product is washed with water, dried, and sieved to obtain the phosphor of the present invention.

The phosphor of the present invention obtained by the manufacturing method described above uses zinc sulfide as a matrix, silver as an activator, indium as a first co-activator, and is selected from among chlorine, bromine, iodine, fluorine and aluminum. (one kind is used as a second co-activator, and the amount of the above-mentioned activator, the first co-activator and the second co-activator is 5 x 10' of the above-mentioned zinc sulfide matrix, respectively)
10-1 to 10-1% by weight, 10-6 to 10-1% by weight and 5X10' to s
% by weight of the phosphor. This phosphor is a conventional Zn
S: Like Ag and X phosphors, it emits high-intensity blue light when excited by electron beams, ultraviolet light, etc.
The 0% afterglow time depends on the activation amount of indium and is different from the conventional Z
nS: Several tens to hundreds of times longer than Ag, X fluorophore.

As described above, the phosphor of the present invention exhibits a long afterglow, and its afterglow characteristics vary depending on the activation amount of the first coactivator indium. It also affects. That is, in the phosphor of the present invention, as the amount of indium activation increases, the luminance of the emitted light decreases, and when the amount of indium activation increases significantly, the purity of the emitted light color decreases. However, as mentioned above, the trace amount of sulfur contained in the phosphor of the present invention has the effect of suppressing the reduction in luminance caused by activating indium. ZnS is shown having the same composition except that it does not contain any traces of sulfur.

Further, as explained earlier, the phosphor of the present invention is heated to 1050°C.
The phosphor has a phase transition point in the vicinity, and the phosphor obtained by firing at a temperature below 1050°C has the cubic crystal system as the main crystal phase, whereas the phosphor obtained by firing at a temperature higher than 10500°C has the cubic crystal system as the main crystal phase. The main crystal phase of the resulting phosphor is a hexagonal system.

When comparing a phosphor with a cubic crystal system as the main crystal phase and a phosphor with a hexagonal system as the main crystal phase, the luminance of the former is approximately 1.3 to 2 times higher than that of the latter; Regarding phosphors with higher emission color purity and a comparatively lower indium activation amount bt, the former has a 10% longer afterglow time than the latter. From these points of view, a phosphor having a cubic system as its main crystal phase is more preferable as a blue-emitting phosphor for a high-resolution cathode ray tube than a phosphor having a hexagonal system as its main crystal phase.

Note that the emission spectrum of a phosphor having a cubic crystal system as its main crystal phase is slightly on the longer wavelength side than that of a phosphor having a hexagonal system as its main crystal phase.

Figure 1 shows the emission spectrum of the phosphor of the present invention compared to that of conventional Zn.
The following is an example of comparison with the emission spectrum of S:Ag,X phosphor. In FIG. 1, curve a represents conventional ZnS with cubic crystal system as the main crystal phase in which the activation amounts of silver and chlorine are 10-% and 10-4% by weight of the zinc sulfide matrix, respectively. The emission spectra of the light body, curves and C, have the same activation amounts of silver and chlorine as above, and the indium activation amount and sulfur content are 10-2% by weight and 10% by weight of the zinc sulfide matrix, respectively.
-4% by weight of the sulfur-containing ZnS whose main crystal phases are cubic and hexagonal systems: Ag, In,
The emission spectrum of the C1 phosphor, curve d, is the same as the activation amount of silver and chlorine and the sulfur content as above, and the indium activation amount is 2 X 10-''% by weight of the zinc sulfide matrix. Sulfur-containing ZnS whose main crystalline phase is
: Emission spectra of Ag, In, CI phosphors.

As illustrated in FIG.
C and d) are conventional ZnS:Ag,X fluorophores (
Like curve a), it shows blue light emission. Also, curve d
As is clear from the comparison, in the phosphor of the present invention, when the amount of indium activation increases significantly (more than 2X 10-"ilt amount %), the half-width of the emission spectrum becomes wider and the color purity of the emitted color decreases. The emission spectrum (curve b) of the phosphor of the present invention with an indium activation amount of 10% by weight has a narrower half-width than the emission spectrum (curve a) of the conventional ZnS:Ag,X phosphor. Therefore, the phosphor of the present invention having an indium activation amount of at least 10% by weight or less emits blue light with higher color purity than the conventional ZnS:Ag,X phosphor. As is clear from the comparison, in the phosphor of the present invention, the phosphor with a cubic crystal system as the main crystal phase (curve b) has a slightly smaller crystalline structure than the phosphor with a hexagonal crystal system as the main crystal phase (curve C). It has an emission spectrum on the long wavelength side.

Note that the changes in the emission spectrum (changes in the color purity of the emitted light) due to changes in the amount of indium activation in the phosphor of the present invention explained above with reference to FIG.

It is almost the same as the case of In,X' fluorophore. That is, the trace amount of sulfur contained in the phosphor of the present invention has almost no effect on the emission spectrum (color purity of emitted light) of the phosphor.

Figure 2 shows the afterglow characteristics of the phosphor of the present invention compared to conventional ZnS:
3 is a graph illustrating a comparison with the afterglow characteristics of Ag p X phosphor. In FIG. 2, curve a is a conventional ZnS:Ag, CIX whose main crystal phase is a cubic system in which the activation amounts of scissors and chlorine are 10-21% by weight and 10-4% by weight of the zinc sulfide matrix, respectively. The afterglow characteristics after the phosphor electron beam excitation is stopped, the curves are silver and salt, and the activation amount of the vine is the same as above, and the indium 1 activity and sulfur content are respectively 2 X to” of the zinc sulfide matrix. 1% by weight and 10-4
This is the afterglow characteristic of the sulfur-containing ZnS:Ag, In, C6 phosphor having a cubic main crystal phase of the present invention in terms of weight percent after termination of electron beam excitation.

As is clear from FIG. 2, the sulfur-containing ZnS of the present invention
: Ag, In, C1 phosphor is conventional ZnS:
It has a significantly longer afterglow compared to Ag and CIX phosphors. While the 10% afterglow time of the conventional ZnS:Ag, CIX phosphor is about 150 microseconds, the 10% afterglow time of the sulfur-containing ZnS:Ag, In, C1 phosphor of the present invention is about 40 microseconds. milliseconds, and conventional ZnS
: Ag, 250 times more than CIX phosphor.

Figure 3 shows the amount of indium activation in the phosphor of the present invention and 1
It is a graph illustrating the relationship with 0% afterglow time. In Figure 3, curve a shows activation amounts of silver and chlorine of 10-1% by weight and 10-1% by weight of the zinc sulfide matrix, respectively, and a sulfur content of 10-4% by weight of the zinc oxide matrix. Sulfur-containing ZnS whose main crystal phase is cubic system: Ag sIn
, The above relationship in the CIX phosphor, the curve is a sulfur-containing ZnS whose main crystal phase is a hexagonal system in which the activation amounts of silver and chlorine and the sulfur content are the same as above: Ag,
This is the above relationship for In and C1 fluorophores. In addition,
The mark ○ shown on the vertical axis representing the 10% afterglow time in FIG. 3 indicates conventional ZnS whose main crystal phase is cubic system with the same activation amounts of silver and chlorine as above: Ag, CIX
The phosphor has a 10% afterglow time (approximately 150 microseconds).

As illustrated in FIG. 3, the phosphor of the present invention, in which the indium activation amount is in the range of 10-6 to 10-1% by weight of the zinc sulfide matrix, has a cubic or macrogonal crystal phase. In both cases, the 10% afterglow time is the same as that of conventional ZnS: Ag
, X Several tens to hundreds of times longer than the phosphor. In particular, the phosphor of the present invention having an indium activation amount in the range of 5.times.10" to 10@-1% by weight has a significantly long 10% afterglow time.

However, as explained above, the luminance of the phosphor of the present invention decreases as the amount of indium activation increases.
Furthermore, the luminescent color purity of the phosphor of the present invention decreases when the amount of indium activation increases significantly. Taking into consideration the emission brightness and emission color purity, the preferred indium activation amount of the phosphor of the present invention is 5.times.10' to 10.sup.-2% by weight.

As illustrated in FIG. 3, the 10% afterglow time of the phosphor of the present invention having an indium activation amount within this range is about 5 to 55.
Although it is milliseconds, this 10% afterglow time is sufficient for a blue-emitting phosphor for high-resolution cathode ray tubes.

As explained above, among the phosphors of the present invention, a phosphor having a cubic crystal system as its main crystal phase has a luminance of about 1.3 to 100% higher than a phosphor having a hexagonal system as its main crystal phase. Twice as expensive. In addition, the preferred indium activation amount range (5X 10-' to 10
%), a phosphor having a cubic crystal system as its main crystal phase has a 10% longer afterglow time than a phosphor having a hexagonal system as its main crystal phase. From these points of view, a phosphor having a cubic system as its main crystal phase is more preferable as a blue-emitting phosphor for a high-resolution cathode ray tube than a phosphor having a hexagonal system as its main crystal phase. In particular, the indium activation amount is 5 x 10-6
A phosphor having a cubic crystal system as a main crystal phase in the range of 10-1% by weight is most suitable for high-resolution cathode ray tubes.

Note that FIG. 3 shows sulfur-containing ZnS: Ag, In,
This is a graph showing the relationship between the indium activation amount and the 10% afterglow time for the C1 phosphor, and the indium activation amount also changes when the second co-activator is bromine, iodine, fluorine or aluminum. It was confirmed that the relationship between 10% afterglow time and 10% afterglow time has the same tendency as shown in FIG.

The relationship between the amount of indium activation and the 10% afterglow time in the phosphor of the present invention explained above with reference to FIG. The relationship is almost the same as that with light time.

That is, the trace amount of sulfur contained in the phosphor of the present invention has almost no effect on the afterglow properties of the phosphor.

As mentioned above, the presence of a trace amount in the phosphor of the present invention has almost no effect. However, the trace amount of sulfur contained in the phosphor of the present invention has the effect of increasing the luminance of the phosphor. Therefore, the phosphor of the present invention has the same composition as ZnS:Ag,I except that it does not contain a trace amount of sulfur.
n.

It emits light with higher brightness than the X phosphor.

Figure 4 shows the relationship between the amount of indium activation and the luminance in the phosphor of the present invention using sulfur-free ZnS: Ag.
, In, and X phosphors are graphs illustrating a comparison of the relationship between the amount of indium activation and luminance. Fourth
In the figure, curve a indicates that the activation amounts of silver and chlorine are 10"fE amount% and 10-4% by weight of the zinc sulfide matrix, respectively.
Sulfur-free Zn whose main crystal phase is cubic system
S: Ag, In, CA! The above relationships and curves in the phosphor are the same as above, and the sulfur content is 101% by weight of the zinc sulfide matrix. ZnS: Ag
, In, and CIX phosphors.

As illustrated in FIG. 4, the phosphor of the present invention or sulfur-free ZnS:Ag,In.

In any of the X phosphors, the luminance decreases as the amount of indium activation increases.

However, as is clear from FIG. 4, the phosphor of the present invention exhibits higher luminance than the ZnS:Ag,In,X phosphor having the same composition except that it does not contain a trace amount of sulfur. That is, the trace amount of sulfur contained in the phosphor of the present invention has the effect of suppressing the reduction in luminance caused by activation of indium. Such an effect occurs when the sulfur content of the zinc sulfide matrix ranges from 5 x 10-' to 1
This seems to be particularly noticeable when the amount is in the range of o-'ii amount %. As explained above, the luminescent color purity and afterglow characteristics of the phosphor of the present invention are those of the ZnS:Ag, In, X phosphor having the same composition except that it does not contain sulfur. is almost the same. Therefore, taking into account the luminance, it can be said that the phosphor of the present invention is more suitable for high-resolution cathode ray tubes than the sulfur-free ZnS:Ag,In,X phosphor.

As explained above, the present invention provides a long-lasting blue-emitting phosphor that is particularly useful as a blue-emitting phosphor for high-resolution cathode ray tubes, and has very high industrial utility value. It is. In addition, in the phosphor of the present invention, a part of the first coactivator indium may be replaced with gallium, scandium, or both. Further, the phosphor of the present invention may be further activated with an activator such as copper, gold, divalent europium, bismuth, or antimony. Furthermore, in the phosphor of the present invention, a portion of the zinc in the zinc sulfide matrix may be substituted with cadmium, or a portion of the sulfur may be substituted with selenium in order to shift the emission wavelength to a somewhat longer wavelength side.

Next, the present invention will be explained by examples.

Example 1 Ammonium sulfide was added to an aqueous zinc sulfate solution while the pH value of the aqueous solution was constantly maintained at 5 by addition of sulfuric acid to precipitate zinc sulfide.

The raw zinc sulfide powder thus prepared contained 7% by weight of zinc sulfide of non-stoichiometric sulfur. Zinc sulfide raw powder 2140 containing more sulfur than this stoichiometric amount
g (i.e. 2000 g zinc sulfide + 140 p sulfur),
Silver nitrate (AgN0a) 032g, indium nitrate ACI
n (NOs)a e3H20]0.618. ! i'
, sodium chloride A (NaC1) 10g and magnesium chloride (MgC1z) 10. ! After thoroughly mixing i' using a ball mill, appropriate amounts of sulfur and carbon were added and the mixture was filled into a quartz crucible. After the quartz crucible was covered, the crucible was placed in an electric furnace and fired at a temperature of 950°C for 3 hours. During this firing, the inside of the crucible is in a carbon disulfide atmosphere. The fired product obtained after firing was taken out from the crucible, washed with water, dried, and passed through a sieve. In this way, ZnS:Ag, In, C1 phosphors were obtained in which the activation amounts of silver, indium, and chlorine and the sulfur content were 10-1% by weight and 10-1% by weight, respectively, based on the zinc sulfide matrix. .

The above-mentioned phosphor has a first emission spectrum under electron beam excitation.
It exhibited blue light emission with high color purity as shown by the curve in the figure, and the 10% afterglow time after the electron beam excitation was stopped was about 55 milliseconds.

Example 2 The same process as in Example 1 was carried out except that 6.1.8 g of indium nitrate was used. -1 wt%, 10-4 wt% and 1o-4 wt% sulfur-containing ZnS':'Ag, In,
A C6 phosphor was obtained.

The phosphor exhibited blue light emission under electron beam excitation, and the 10% afterglow time after the electron beam excitation was stopped was 12 milliseconds.

Example 3 Same as Example 1 except that 124 g of indium nitrate was used, and the activation amount of silver, indium, and chlorine and the sulfur content were 10-1 mass % and 2 X 10- of the zinc sulfide matrix, respectively. 'wt%, 10-4 wt% and 1
〇-1% sulfur-containing ZnS: Ag, In
, C1 phosphor was obtained.

The above phosphor emits blue light with high color purity under electron beam excitation, and the 10% afterglow time after the electron beam excitation is stopped is 14
It was milliseconds.

Example 4 Same as Example 1 except that 1.2369 indium nitrate was used, and the activation amount of silver, indium and chlorine and the sulfur content were each 101% by weight of the zinc sulfide matrix.
, 2 X to-1% by weight, 10-4% by weight and 10-
ZnS containing 4% by weight of sulfur: Ag, In
, C1 phosphor was obtained.

The above-mentioned phosphor has a first emission spectrum under electron beam excitation.
It exhibited blue light emission as shown by curve d in the figure, and the 10% afterglow time after the electron beam excitation stopped was about 50 milliseconds.

[Brief explanation of the drawing]

FIG. 1 illustrates the emission spectrum of the blue-emitting phosphor of the present invention in comparison with that of a conventional ZnS:Ag,X blue-emitting phosphor. FIG. 2 is a graph illustrating the afterglow characteristics of the blue-emitting phosphor of the present invention in comparison with the afterglow characteristics of a conventional ZnS:Ag,X blue-emitting phosphor. FIG. 3 is a graph illustrating the relationship between the amount of indium activation and the 10% afterglow time in the blue-emitting phosphor of the present invention. Figure 4 shows the relationship between the amount of indium activation and the luminance in the blue-emitting phosphor of the present invention using sulfur-free ZnS:
2 is a graph illustrating a comparison of the relationship between the amount of indium activation and luminance in Ag, In, X blue light emitting phosphors.

Claims (4)

[Claims] (1) Zinc sulfide is used as a matrix, silver is used as an activator, indium is used as a first coactivator, and at least one of chlorine, bromine, iodide, fluorine, and aluminum is used as a second coactivator. and the amounts of the activator, first co-activator and second co-activator are 5×1 of the zinc sulfide matrix, respectively.
0'-' to 10-'% by weight, 10-6 to 10-1% by weight, and 5 x 10-' to 5 x 10-2% by weight, and the sulfur is 10-5 to 8% by weight of the zinc sulfide matrix. A long-afterglow blue-emitting zinc sulfide phosphor, characterized in that it contains 10""% by weight of X. (2) The phosphor according to claim 1, wherein the amount of the first co-activator is 5 x 10-6 to 10-2% by weight. (3) The above sulfur content is 5 x 10"" to 10-
The phosphor according to claim 1 or 2, characterized in that the amount is 3% by weight. (4) The phosphor according to any one of claims 1 to 3, wherein the main crystal phase is cubic.