JPS637595B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to long afterglow blue emitting zinc sulfide phosphors.

It is desired to use high-resolution cathode ray tubes for computer terminal display devices that display detailed characters and graphics, display devices for aircraft control systems, and the like. An effective way to improve the resolution of cathode ray tubes is to increase the scanning speed of the fluorescent film using an electron beam by 2 times higher than that of ordinary cathode ray tubes for display devices.
It is known that the phosphor that makes up the phosphor film of such a high-resolution cathode ray tube has a 10% afterglow time (after excitation stops, the luminance decreases to 10% of the excitation level). It is necessary that the time required for the phosphor film to be formed is several tens to hundreds of times longer than that of the phosphor that constitutes the phosphor film of a typical cathode ray tube for display devices.

Conventionally, long-afterglow phosphors that can be used in the above high-resolution cathode ray tubes include manganese- and arsenic-activated zinc silicate green-emitting phosphors (Zn ₂ SiO ₄ :Mn, As), and manganese-activated potassium/magnesium fluoride. Orange-emitting phosphor (KMgF ₃ Mn), lead- and manganese-activated calcium silicate orange-emitting phosphor (CaSiO ₃ :Pb,
Mn), manganese-activated magnesium fluoride red-emitting phosphor (MgF ₂ :Mn), manganese-activated zinc/magnesium orthophosphate red-emitting phosphor [(Zn,
Mg) ₃ (PO ₄ ) ₂ :Mn] and the like are known, but there is no known long-afterglow blue-emitting phosphor that can be used in the above-mentioned high-resolution cathode ray tubes. 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 requests, silver, which is used in cathode ray tubes for black and white television, cathode ray tubes for color television, etc., is used as an activator, and chlorine, bromine, iodine, etc.
A short-afterglow blue-emitting zinc sulfide phosphor (ZnS: Ag, X, where X is a coactivator of at least one of fluorine and aluminum) The above-mentioned long-afterglow green-emitting phosphor and red-emitting phosphor are mixed in a specific ratio with at least one type of phosphor (at least one type), and this mixed phosphor (called a light blue phosphor)
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 10% afterglow time of the ZnS:Ag, 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 blue emitting phosphor suitable for use in the above-mentioned high resolution cathode ray tube. The purpose is to provide the body.

In order to achieve the above object, the present inventors developed the above-mentioned ZnS, which is widely used as a blue-emitting phosphor.
Various studies have been conducted on making Ag,X phosphors into phosphors with long afterglow properties. As a result, when zinc sulfide is activated with an appropriate amount of indium along with an appropriate amount of silver and X (where X is at least one of chlorine, bromine, iodine, fluorine, and aluminum), ZnS:Ag, 10% more than X phosphor
It has been found that it is possible to obtain a blue-emitting phosphor with a significantly long afterglow time. This long afterglow ZnS:
In Ag, In, X blue-emitting phosphors, indium also affects the luminance, and as the amount of indium activation increases, the luminance of the phosphor decreases. Of course, when using ZnS:Ag, In, We conducted research on increasing the luminance of phosphors. 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. It has been found that the reduction in luminance caused by indium activation can be considerably suppressed.

The present invention has been made based on the above findings. That is, the long-afterglow blue-emitting phosphor of the present invention uses zinc sulfide as a matrix, silver as an activator, indium as a first co-activator, and chlorine, bromine, iodine, fluorine, and aluminum. as a second co-activator, at least one of the above-mentioned activators,
The amounts of the first co-activator and the second co-activator are 5 x 10 ^-4 to 10 ^-1 weight %, 10 ^-6 to 10 ^-1 weight % and 5 x 10 ^- of the zinc sulfide matrix, respectively. ⁶ to 5×
10 ^-2 % by weight, and sulfur is contained in an amount of 10 ^-5 to 8×10 ^-1 % by weight of the zinc sulfide matrix.

The above blue-emitting zinc sulfide phosphor of the present invention is similar to the conventional blue-emitting zinc sulfide phosphor.
ZnS: The 10% afterglow time after stopping excitation by electron beams, ultraviolet rays, etc. is several tens to hundreds of times longer than that of Ag and X blue-emitting phosphors. The phosphor of the present invention has a cubic system or a hexagonal system as its main crystal phase depending on the annealing temperature during production, but a phosphor with a cubic system as its main crystal phase is more likely to have a hexagonal system. The former is 10% more luminous than the latter in the indium activation amount range that provides a phosphor with higher luminance and luminance color purity than a phosphor with a main crystalline phase of
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 all values of the 10% afterglow time described in this specification are values when the current density of the stimulating electron beam is 1 μA/cm ² .

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 (i) raw zinc sulfide powder containing a large amount of sulfur during refining (base material and raw material for sulfur), (ii) silver compounds such as silver nitrate, silver sulfide, and silver halide (activating agent). raw materials) (iii) indium compounds such as indium nitrate, indium sulfide, and indium halides (first coactivator raw materials), and (iv) alkali metals (Na, K, Li, Rb, and Cs)
and alkaline earth metals (Ca, Mg, Sr, Zn,
At least one compound selected from the group consisting of chlorides, bromides, iodides, and fluorides of Cd and Ba), and aluminum compounds such as aluminum nitrate, aluminum sulfate, aluminum oxide, and aluminum halide (second compound); activator raw material) is used. The base material and sulfur raw material in (i) above are prepared, for example, by adding ammonium sulfide to a weakly acidic zinc sulfate aqueous solution with a pH of 6 to 4 while maintaining the PH value of the aqueous solution constant to precipitate zinc sulfide. be able to. The amount of sulfur other than the stoichiometric amount contained in the raw zinc sulfide powder prepared in this way depends on the PH value of the aqueous solution at the time of precipitation,
The lower the PH value (that is, the higher the acidity), the greater the amount. Generally, 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 raw zinc sulfide powder mentioned in (i) above, which is both the base material and the raw material for the trace amount of sulfur contained in the obtained phosphor, is prepared by taking into consideration the firing temperature, firing time, etc. during the production of the phosphor. 10 ^-5 of zinc sulfide matrix
A material containing sulfur in an amount other than the stoichiometric amount that can achieve the target sulfur content, which is selected from the range of 8 x 10 ^-1 % by weight, is used.

The base material and sulfur raw material in (i) above, the activator raw material in (ii) and the first co-activator raw material in (iii) are determined based on the amount of silver in the activator raw material in (ii) and the amount of silver in the activator raw material in (iii). The amount of indium in the first coactivator raw material of (i) is 5 × 10 ^-4 to the amount of zinc sulfide contained in the base material and sulfur raw material of (i), respectively.
It is used in an amount ratio of 10 ^-1 % by weight and 10 ^-6 to 10 ^-1 % by weight. The second coactivator raw material (iv) is the amount of at least one of chlorine, bromine, iodine, fluorine, and aluminum contained in the obtained phosphor (i.e., the amount of the second coactivator). The amount used is such that the amount (amount) is 5 x 10 ^-6 to 5 x 10 ^-2 % by weight of the zinc sulfide matrix. That is, like silver and indium, most of the aluminum in the second coactivator raw material remains in the obtained phosphor and becomes the second coactivator; Most of the halogen in the agent raw material is lost during firing, and only a small portion remains in the resulting phosphor. Therefore, the above-mentioned alkali metal or alkaline earth metal halide, which is a raw material for halogen, is used in an amount that contains several tens to hundreds of times as much halogen as the desired amount of halogen activation, depending on the firing temperature, etc. .
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, A portion 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. This phosphor raw material is mixed by adding the base material and sulfur raw material in (i) above, the activator raw material in (ii) above, the first co-activator raw material in (iii), and the second raw material in (iv). The co-activator raw material may be added as a solution and carried out in a wet manner. In this case, the phosphor raw material mixture obtained after mixing is sufficiently dried.

Next, the obtained phosphor raw material mixture was placed in a quartz crucible.
It is filled into a heat-resistant container such as a quartz tube and fired. Firing is carried out in hydrogen sulfide atmosphere, sulfur vapor atmosphere,
The test is carried out in a sulfidic atmosphere such as a carbon disulfide atmosphere.
A suitable firing temperature is 600 to 1200°C. When the firing temperature is higher than 1050°C, a phosphor with a hexagonal system as the main crystal phase is obtained;
In the following cases, a phosphor having a cubic crystal system as the main crystal phase can be obtained. That is, the phosphor of the present invention is
It has a phase transition point around 1050℃. 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 600 to 1050
It is preferably 800°C to 800°C, more preferably 800 to
The temperature is 1050℃. The firing time depends on the firing temperature used,
Although it varies depending on the amount of the phosphor raw material mixture filled in the heat-resistant container, 0.5 to 7 hours is appropriate in the above firing temperature range. 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 host, silver activator, indium as the first co-activator, chlorine, bromine, iodine, fluorine, and aluminum. at least one of them is used as a second co-activator, the above-mentioned activator,
The amounts of the first co-activator and the second co-activator are 5 x 10 ^-4 to 10 ^-1 weight %, 10 ^-6 to 10 ^-1 weight % and 5 x 10 ^- of the zinc sulfide matrix, respectively. ⁶ to 5×
10 ^-2 % by weight and sulfur in an amount of 10 ^-5 to 8 x 10 ^-1 % by weight based on the zinc sulfide matrix. Like conventional ZnS:Ag and Conventional ZnS depending on:Ag,X
It is several tens to hundreds of times longer than the fluorescent material. 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. It exhibits higher luminance than the ZnS:Ag, In, X phosphor, which has the same composition except that it does not contain a trace amount of sulfur.

Furthermore, as explained earlier, the phosphor of the present invention
It has a phase transition point around 1050℃, and the phosphor obtained by firing at a temperature below 1050℃ has a cubic crystal system as the main crystal phase, while the phosphor obtained by firing at a temperature higher than 1050℃ has a cubic crystal phase. The phosphor obtained by this process has a hexagonal crystal system as its main crystal phase. 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 former has a luminance that is approximately higher than the latter.
For phosphors with a relatively low amount of indium activation, which is 1.3 to 2 times higher and has higher emission brightness and emission color purity, 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.

FIG. 1 illustrates the emission spectrum of the phosphor of the present invention in comparison with that of a conventional ZnS:Ag,X phosphor. In Figure 1, curve a represents conventional ZnS whose main crystal phase is a cubic system in which the activation amounts of silver and chlorine are 10 ^-2 % and 10 ^-4 % by weight of the zinc sulfide matrix, respectively: Ag, Cl In the emission spectrum of the phosphor, curves b and c, the activation amounts of silver and chlorine are the same as above, and the indium activation amount and sulfur content are 10 ^-2 % and 10 ^-4 % by weight of the zinc sulfide matrix, respectively. % of the sulfur-containing ZnS:Ag, In, Cl phosphor of the present invention with cubic and hexagonal main crystal phases,
Curve d shows that the activation amount of silver and chlorine and the sulfur content are the same as above, and the indium activation amount is 2 x 10 ^-2 % by weight of the zinc sulfide matrix.The main crystal phase is the cubic system of the present invention. Emission spectrum of sulfur-containing ZnS: Ag, In, Cl phosphor.

As illustrated in FIG. 1, the phosphor of the present invention (curves b, c and d) exhibits blue emission similar to the conventional ZnS:Ag,X phosphor (curve a). Furthermore, as is clear from the comparison between curve b and curve d, when the indium activation amount of the phosphor of the present invention increases significantly (2×10 ^-2 weight % or more), the half-width of the emission spectrum becomes wider and the emission color becomes larger. color purity decreases. The emission spectrum (curve b) of the phosphor of the present invention with an indium activation amount of 10 ^-2 % by weight is different from that of the conventional ZnS:Ag,
The half width is narrower than the emission spectrum of the phosphor (curve a), so the indium activation amount is at least
The phosphor of the present invention, which is 10 ^-2 % by weight or less, is
ZnS:Exhibits blue light emission with higher color purity than Ag and X phosphors. Furthermore, as is clear from the comparison between curve b and curve c, in the phosphor of the present invention, the phosphor having a cubic system as the main crystal phase (curve b) is different from the phosphor having a hexagonal system as the main crystal phase. (curve c) has an emission spectrum on the slightly longer wavelength side.

Note that the changes in the emission spectrum (changes in the color purity of the emitted light color) due to changes in the amount of indium activation in the phosphor of the present invention explained above with reference to FIG. , In, and X phosphors. 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 the conventional one.
It is a graph illustrating a comparison with the afterglow characteristics of ZnS:Ag and X phosphors. In Figure 2, curve a shows the activation amount of silver and chlorine, respectively, in the zinc sulfide matrix.
Curve b shows the afterglow characteristics of ZnS:Ag,Cl phosphors with the main crystalline phase of the conventional cubic system, which are 10 ^-2 and 10 ^-4 wt%, after electron beam excitation is stopped. The activation amount is the same as above, and the indium activation amount and sulfur content are respectively 2× of the zinc sulfide matrix.
The sulfur-containing ZnS with the main crystalline phase of the cubic system of the present invention, which is 10 ^-3 % by weight and 10 ^-4 % by weight: Ag, In,
This is the afterglow characteristic of a Cl phosphor after electron beam excitation is stopped.

As is clear from FIG. 2, the sulfur-containing
ZnS:Ag, In, Cl phosphor is conventional ZnS:Ag, Cl
It has a significantly longer afterglow compared to fluorescent materials. Traditional
ZnS: The 10% afterglow time of Ag, Cl phosphor is about 150 microseconds, whereas the sulfur-containing ZnS of the present invention:
The 10% afterglow time of the Ag, In, Cl phosphor is approximately 40 milliseconds, which is more than 250 times that of the conventional ZnS:Ag, Cl phosphor.

FIG. 3 is a graph illustrating the relationship between the amount of indium activation and the 10% afterglow time in the phosphor of the present invention. In Figure 3, curve a shows that the activation amounts of silver and chlorine are 10 ^-2 % and 10 -4% by weight of the zinc sulfide matrix, respectively, and the sulfur content is 10 -2% and 10 ^-4 % by weight of the zinc sulfide matrix.
The above relationship in the sulfur-containing ZnS:Ag, In, Cl phosphor with cubic crystal system as the main crystal phase with 10 ^-4 % by weight,
Curve b shows the above relationship in a sulfur-containing ZnS:Ag, In, Cl phosphor having a hexagonal system as the main crystal phase and having the same activation amounts of silver and chlorine and the same sulfur content as above. In addition, the mark ○ shown on the vertical axis representing the 10% afterglow time in Figure 3 indicates the conventional ZnS:Ag whose main crystal phase is the cubic system with the same activation amounts of silver and chlorine as above. , 10% afterglow time of Cl phosphor (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 hexagonal crystal phase. In both cases, the afterglow time is 10% lower than that of the conventional
ZnS: Ag, several tens to hundreds of times longer than X fluorophore.
In particular, the indium activation amount is 5×10 ^-4 to 10 ^-1 % by weight.
The phosphor of the present invention in the range of 10% afterglow time is significantly long. However, as explained above, the luminance of the phosphor of the present invention decreases as the amount of indium activation increases, and the purity of the luminescent color of the phosphor of the present invention decreases as the amount of indium activation increases. When it increases, it decreases. Taking into consideration the emission brightness and emission color purity, the preferred indium activation amount of the phosphor of the present invention is 5 x 10 ^-6 to 10 ^-2 % by weight. Third
As illustrated in the figure, the 10% afterglow time of the phosphor of the present invention having an indium activation amount within this range is about 5 to 55 milliseconds, but this 10% afterglow time is suitable for high resolution cathode ray tubes. This is sufficient as a blue-emitting phosphor.

As explained above, among the phosphors of the present invention, a phosphor having a cubic crystal system as a main crystal phase has a luminance of about 1.3 to 2 times higher than a phosphor having a hexagonal system as a main crystal phase.
twice as expensive. Furthermore, in the preferred indium activation amount range (5 x 10 ^-6 to 10 ^-2 % by weight), the phosphor having a cubic system as its main crystal phase is more effective than the phosphor having a hexagonal system as its main crystal phase. 10% long afterglow time. 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, a phosphor having an indium activation amount in the range of 5×10 ^-6 to 10 ^-2 weight % and having a cubic crystal system as its main crystal phase is most suitable for high-resolution cathode ray tubes.

Figure 3 is a graph showing the relationship between indium activation amount and 10% afterglow time for a sulfur-containing ZnS:Ag, In, Cl phosphor. In the case of fluorine or aluminum, the relationship between indium activation amount and 10% afterglow time is the third
It was confirmed that the trend was similar to that shown in the figure.

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 the 10% afterglow 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 trace amount of sulfur contained in the phosphor of the present invention has almost no effect on the luminous color purity and afterglow characteristics of the phosphor. 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 exhibits higher luminance than a ZnS:Ag, In, X phosphor having the same composition except that it does not contain a trace amount of sulfur.

Figure 4 shows the relationship between the amount of indium activation and luminance in the phosphor of the present invention, which does not contain sulfur.
It is a graph illustrating a comparison of the relationship between the amount of indium activation and luminance in a ZnS:Ag, In, X phosphor. In Figure 4, curve a indicates that the activation amount of silver and chlorine is 10 ^-2 % by weight of the zinc sulfide matrix.
and 10 ^-4 % by weight of sulfur-free ZnS with a cubic system as the main crystal phase: The above relationship in the Ag, In, Cl phosphor shows that the activation amounts of silver and chlorine are the same as above. Yes, the sulfur content is higher than that of the zinc sulfide matrix.
This is the above relationship in the sulfur-containing ZnS:Ag, In, Cl phosphor of the present invention whose main crystal phase is cubic system, which is 10 ^-4 % by weight.

As illustrated in FIG. 4, the luminance of the phosphor of the present invention or the sulfur-free ZnS:Ag, In, and X phosphor decreases as the amount of indium activation increases. . however,
As is clear from FIG. 4, the phosphor of the present invention has the same composition except that it does not contain a trace amount of sulfur.
ZnS: Shows higher luminance than Ag, In, and X phosphors. 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. This effect occurs when the sulfur content is between 5×10 -5 and 5×10 ⁻⁵ of the zinc sulfide matrix.
This appears to be particularly noticeable in the range of 10 ^-3 % by weight. As explained above, the luminescent color purity and afterglow characteristics of the phosphor of the present invention are the same as those of the ZnS:Ag, In, X phosphor having the same composition except that it does not contain sulfur. is almost the same. Taking into account the luminance, it can therefore 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 its industrial utility value is extremely large. be. In addition,
In the phosphor of the present invention, a portion 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.
Further, in the phosphor of the present invention, part of the zinc in the zinc sulfide matrix may be replaced by cadmium, or part of the sulfur may be replaced by selenium, in order to shift the emission wavelength to a somewhat longer wavelength side.

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

Example 1 Ammonium sulfide was added to an aqueous solution of zinc sulfate while constantly maintaining the pH value of the aqueous solution at 5 by adding sulfuric acid to precipitate zinc sulfide. The raw zinc sulfide powder thus prepared contained 7% by weight of zinc sulfide of non-stoichiometric sulfur. 2140g raw zinc sulfide powder containing more sulfur than this stoichiometric amount
(i.e. zinc sulfide 2000g + sulfur 140g), silver nitrate (AgNO ₃ ) 0.32g, indium nitrate [In(NO ₃ ) ₃ .
3H ₂ O〕0.618g, sodium chloride (NaCl) 10g
After thoroughly mixing 10 g of magnesium chloride (MgCl ₂ ) using a ball mill, appropriate amounts of sulfur and carbon were added and the mixture was filled into a quartz crucible. After covering the quartz crucible, place the crucible in an electric furnace and heat it to 950℃.
Firing was carried out at a temperature of 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, silver
Sulfur content with activation amount of indium and chlorine and sulfur content of 10 ^{-2 wt} %, 10 ^-2 wt%, 10 ^-4 wt% and 10 ^-4 wt% of zinc sulfide matrix, respectively
A ZnS:Ag, In, Cl phosphor was obtained.

The above phosphor exhibits blue light emission with high color purity, whose emission spectrum is shown by curve b in Figure 1 under electron beam excitation, and the 10% afterglow time after the electron beam excitation stops is approximately 55 milliseconds. It was hot.

Example 2 In the same manner as in Example 1 except that 6.18 g of indium nitrate was used, the activation amounts of silver, indium, and chlorine and the sulfur content were changed to the zinc sulfide matrix
10 ^-2 wt%, 10 ^-1 wt%, 10 ^-4 wt% and 10 ^-4
A sulfur-containing ZnS:Ag, In, Cl phosphor with weight % was obtained.

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

Example 3 Same as Example 1 except that 0.0124 g of indium nitrate was used. The activation amount of silver, indium and chlorine and the sulfur content were respectively 10 ^-2 % by weight and 2 x 10 ^-4 of the zinc sulfide matrix. Sulfur-containing ZnS with wt%, ^10-4 wt% and ^10-4 wt%: Ag, In, Cl
I got a phosphor.

The above-mentioned phosphor exhibited blue light emission with high color purity under electron beam excitation, and the 10% afterglow time after the electron beam excitation stopped was 14 milliseconds.

Example 4 Same as Example 1 except that 1.236 g of indium nitrate was used. The activation amount of silver, indium and chlorine and the sulfur content were respectively 10 ^-2 % by weight and 2 x 10 ^-2 of the zinc sulfide matrix. Sulfur-containing ZnS with wt%, ^10-4 wt% and ^10-4 wt%: Ag, In, Cl
I got a phosphor.

The above phosphor exhibited blue light emission whose emission spectrum was shown by curve d in Figure 1 under electron beam excitation, and the 10% afterglow time after the electron beam excitation was 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. Figure 3 shows the indium activation amount and 10% in the blue-emitting phosphor of the present invention.
It is a graph illustrating the relationship with afterglow time. Fourth
The figure shows the relationship between indium activation amount and luminance in the blue-emitting phosphor of the present invention, which does not contain sulfur.
It is a graph illustrating a comparison of the relationship between the amount of indium activation and luminance in a ZnS:Ag, In, X blue light emitting phosphor.

Claims (1)

[Claims] 1 Zinc sulfide is used as a matrix, silver is used as an activator, indium is used as a first co-activator, and at least one of chlorine, bromine, iodine, fluorine and aluminum is used as a second co-activator. As a co-activator, the amounts of the above-mentioned activator, the first co-activator and the second co-activator are 5×10 ^-4 to 10 ^-1 % by weight and 10 ^-6 of the zinc sulfide matrix, respectively.
10 ^-1 % by weight and 5×10 ^-6 to 5×10 ^-2 % by weight, and containing 10 ^-5 to 8×10 ^-1 % by weight of the zinc sulfide matrix. Afterglow blue-emitting zinc sulfide phosphor. 2 The amount of the first co-activator is 5×10 ^-6 to 10 ^-2
% by weight of the phosphor according to claim 1. 3 The above sulfur content is 5×10 ^-5 to 10 ^-3 % by weight
A phosphor according to claim 1 or 2, characterized in that: 4. The phosphor according to any one of claims 1 to 3, wherein the main crystal phase is cubic.