JPH07110943B2 - Luminescent composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Field The present invention relates to improvements in luminescent compositions. More specifically, the present invention relates to a light emitting composition that exhibits high-luminance light emission under low-voltage electron beam excitation with an accelerating voltage of several hundred V or less and that reduces the decrease in light emission luminance over time due to long-term use.

(Prior Art) Conventionally, as a phosphor that emits light with high brightness when excited by a low-speed electron beam with an accelerating voltage of 1 KV or less, particularly several hundred V or less,
Zinc-activated zinc oxide phosphor (ZnO: Zn) is well known. This ZnO: Zn exhibits high-intensity green-white emission when excited by a low-speed electron beam, and a fluorescent display tube using this as a fluorescent film is a display element for desktop electronic calculators, in-vehicle instruments, electric appliances such as VTRs, etc. Is widely used as.

In recent years, as the fields of use of fluorescent display tubes have expanded, it has become desirable to diversify the emission colors of fluorescent display tubes, and the development of luminescent materials that emit light other than green under the excitation of low-speed electron beams has been actively pursued. Came. As a result, several luminescent materials were found, one of which was the composition formula (Zn1-x, C
dx) S (where x is a number satisfying the condition 0 ≦ x ≦ 1) is used as a base material, and zinc (Z
n), silver (Ag), gold (Au), copper (Cu), manganese (Mn)
Etc., and further co-activate halogen, aluminum (Al), gallium (Ga), indium (In), etc., if necessary, sulfide phosphor {hereinafter, composition formula (Zn1-x, Cdx )
S (however, x is a number that satisfies the condition 0 ≦ x ≦ 1)
In the represented sulfides are collectively phosphor as a base "(Zn1-x, Cdx) S series sulfide phosphor" will be abbreviated as} indium oxide (In ₂ O _3), zinc oxide ( ZnO),
A light-emitting composition obtained by mixing a conductive material such as tin oxide (SnO ₂ ) is known (Japanese Patent Publication Nos. 59-33153 and 59-331).
55, JP-A-55-23104, JP-A-55-23106, etc.). These light-emitting compositions are one of the constituents of the light-emitting composition (Zn1-x, Cdx) due to low-speed electron beam excitation with an accelerating voltage of 1 KV or less.
n) and cadmium (Cd) as solid solution ratio (x value) and combination of activator and co-activator, it shows high brightness visible light emission from blue to red. The fluorescent display tube can be multicolored, and the amount of information has dramatically improved.

(Problems to be Solved by the Invention) However, a fluorescent display tube using a light-emitting composition containing a (Zn1-x, Cdx) S-based sulfide phosphor as a main component as a fluorescent film is required to operate for a long time. The (Zn1−
x, Cdx) S-based sulfide phosphor has a major drawback that the brightness of the phosphor screen is likely to decrease and the emission unevenness is likely to occur due to deterioration of the sulfide phosphor or adhesion of decomposition products of the phosphor to the filament. Therefore, there has been a demand for the development of a light-emitting composition which is less likely to be deteriorated or decomposed even after being excited by a low-speed electron beam for a long time, and which is less likely to cause a decrease in emission brightness and uneven emission.

The present invention has been made in view of the above demands, and exhibits high-brightness emission under an accelerating voltage of 1 KV or less, particularly under low-energy electron beam excitation of several hundred V or less, and uses this as a fluorescent film. It is an object of the present invention to provide a light emitting composition which is less likely to be deteriorated or decomposed even when it is made to emit light for a long time, and which is less likely to cause a decrease in light emission luminance with time and uneven light emission on the fluorescent film surface.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present inventors (Zn1-x, Cdx)
As a result of various investigations on the surface treatment method of the S-based sulfide phosphor, especially the surface treatment agent, zirconium (Zr), yttrium (Y), lanthanum (La) was formed on the surface of the (Zn1-x, Cdx) S-based phosphor. ), Scandium (Sc), gallium (Ga), gadolinium (Gd), cerium (Ce) and samarium (Sm) refractory oxides and zinc oxide (ZnO) or heat treatment By using a (Zn1-x, Cdx) S-based sulfide phosphor that has been subjected to a treatment for adhering a zinc (Zn) compound that can be changed to zinc oxide (ZnO) as a constituent of a light emitting composition, The inventors have found that this can be achieved and have reached the present invention.

That is, the light emitting composition of the present invention has a composition formula of (Zn1-x, Cdx) S
(However, x is a number satisfying the condition of 0 ≦ x ≦ 1. The same applies hereinafter).
Zirconium (Zr), Yttrium (Y), Lanthanum (La), Scandium (Sc), Gallium (Ga), Gadolinium (Gd), Cerium (Ce) and Samarium (Sm)
A high-melting point oxide consisting of an oxide of at least one of the elements, and ii) zinc oxide (ZnO) or a zinc (Zn) compound that can be converted to zinc oxide (ZnO) by heat treatment (hereinafter referred to as “Zn compound”). (Hereinafter collectively referred to)) and a conductive material.

Hereinafter, a method for producing the light emitting composition of the present invention will be described.

The method for producing a luminescent composition of the present invention is characterized in that zirconium (Zr), yttrium (Y), lanthanum (La), scandium (Sc), gallium (Ga), gadolinium (Gd),
A (Zn1-x, Cdx) S-based sulfide phosphor obtained by adhering a Zn compound with a refractory oxide consisting of an oxide of at least one element of cerium (Ce) and samarium (Sm) Except that it is used as one of the regenerated products.
It is the same as the conventional light emitting composition composed of a mixture of a phosphor and a conductive substance, and is known as a (Zn1-x, Cdx) S-based sulfide phosphor formed by adhering the above-mentioned high melting point oxide and Zn compound. It is manufactured by mixing or adhering a conductive substance by the method of.

That is, by the method described below,
A (Zn1-x, Cdx) S-based sulfide phosphor to which a Zn compound is attached is prepared.

First of all, it has a desired composition in pure water (Zn1-x, Cd
x) Add S-type sulfide phosphor and stir it sufficiently to suspend it. Used in the light emitting composition of the present invention (Zn1-x, Cdx)
Examples of S-based sulfide phosphors include ZnS: Zn, ZnS: Ag, Cl, ZnS: Ag,
Cl, Li, ZnS: Ag, Al, ZnS: Mn, Cl, (Zn, Cd) S: Cu, Al, (Z
n, Cd) S: Au, Al, (Zn, Cd) S: Au, Cu, Al, CdS: Ag, etc., and the zinc sulfide matrix represented by the composition formula (Zn1-x, Cdx) Activated with an activator such as (Zn), silver (Ag), copper (Cu), gold (Au), manganese (Mn) and, if necessary, aluminum (Al), halogen element (Cl , Br, I or F) and other first co-activators and alkali metal elements (L
i, Na, K, Rb, or Cs), gallium (Ga), indium (I
Any known sulfide formed by co-activating with a second co-activator such as n) can be used. Among these sulfide phosphors, the range of x value in the above composition formula is When a sulfide phosphor having a solid solution of ZnS and CdS in the range of about 0.3 to 0.7 as a matrix is used, the degree of decrease in emission luminance of the obtained light emitting composition with time can be further reduced.

Next, a predetermined amount of alumina and a Zn compound are put into an aqueous suspension of (Zn1-x, Cdx) S-based sulfide phosphor, sufficiently stirred, filtered, and then heated to a temperature of 130 ° C or higher. Or to dry
Alternatively, by evaporating to dryness, a (Zn1-x, Cdx) S-based sulfide phosphor having a high-melting point oxide, which is one of the constituents of the present invention, and a Zn compound attached to the surface is obtained.

As the refractory oxide to be attached to the (Zn1-x, Cdx) S-based sulfide phosphor, a refractory metal oxide having a melting point of at least 1500 ° C. or higher can be used. Among them, zirconium oxide (ZrO _{2 )} , Yttrium oxide (Y ₂ O ₃ ), lanthanum oxide (La ₂ O ₃ ), scandium oxide (Sc ₂ O ₃ ), gallium oxide (Ga ₂ O ₃ ), gadolinium oxide (Gd ₂ O ₃ ), cerium oxide ( Ce ₂ O ₃ ), samarium oxide (Sm ₂ O ₃ ), Z
Most, or all, of the oxides of r, Y, La, Sc, Ga, Gd, Ce and Sm or oxides of these oxides or hydroxides obtained by dehydration of some or all of them by heat treatment. A dehydration product consisting of an oxide (these are collectively referred to as “high melting point oxide” in the present specification) in order to suppress a decrease in emission luminance of the obtained light emitting composition over time. Among these refractory oxides, it is particularly preferable to use a refractory oxide containing at least one metal element selected from Zr, Y, Ce and Sm. From the viewpoint of the emission brightness of the obtained light-emitting composition, these refractory oxides attached to the (Zn1-x, Cdx) S-based sulfide phosphor are ultrafine particles having an average particle size of 1 μm or less. It is especially recommended to use

Zn attached to the (Zn1-x, Cdx) S-based sulfide phosphor
As the compound, zinc oxide (ZnO) or zinc (Zn) hydroxide, sulfate, nitrate, carbonate, halide, hydroxy salt, etc. are thermally decomposed by heat treatment at a temperature of 100 ° C to 700 ° C, Z, at least part of which can turn into ZnO
n compounds are used.

However, when the Zn compound is attached to the (Zn1-x, Cdx) S-based sulfide phosphor together with the refractory oxide, the sulfide phosphor and the refractory oxide are simply suspended as described above. Add the Zn compound to the solution, filter or evaporate to dryness as it is, and add the Zn compound that is soluble in water to the sulfide phosphor with the high-melting-point oxide, and not attach the Zn compound that was added first to the sulfide phosphor. NH ₄ O in this solution
Alkali such as H, NaOH, ammonium carbonate, Zn compound initially added by adding oxalic acid, etc. is precipitated as hydroxide, carbonate, oxalate, etc. It is more preferable to adhere it to the surface in order to suppress a decrease in the emission luminance of the obtained light-emitting composition over time. Therefore, as the Zn compound used, a water-soluble Zn compound such as a sulfate, a nitrate or a halide is used. It is preferably used.

On the other hand, from the viewpoint of the initial emission brightness of the obtained light emitting composition, it is desirable that at least ZnO is finally attached to the surface of the (Zn1-x, Cdx) S-based sulfide phosphor, and therefore,
Among the above-mentioned Zn compounds, the thermal decomposition temperature is low, and it is easy to change to ZnO by applying heat treatment.
Zn hydroxide is used as a compound and is attached to the (Zn1-x, Cdx) S-based sulfide phosphor together with the above-mentioned high melting point oxide, or (Zn1-x, Cdx) S-based sulfide fluorescence. Body and the above-mentioned high-melting-point oxide and zinc ions coexist in the solution to finally precipitate as a hydroxide of Zn by addition of an alkali, and this precipitates together with the high-melting-point oxide in (Zn1-x, Cdx) S system. More preferably, it is attached to the sulfide phosphor.

Next, the (Zn1-x, Cdx) S-based sulfide phosphor formed by adhering the refractory oxide and the Zn compound produced as described above on the surface uses a mortar, ball mill, mixer mill, or the like. And a conductive substance which is the other constituent of the luminescent composition of the present invention is thoroughly mixed, or gelatin and gum arabic are used as an adhesive on the surface of the sulfide phosphor (Japanese Patent Publication No. 54-3677). No. 54), electrostatic coating method (Japanese Patent Publication No. 54)
-44275), a method using an organic binder such as ethyl cellulose or nitrocellulose (Japanese Patent Publication No. 62-33).
The light emitting composition of the present invention can be obtained by depositing a conductive substance by a known method (see Japanese Patent No. 266).

The conductive material used in the light emitting composition of the present invention includes indium oxide (In ₂ O ₃ ), zinc oxide (ZnO), tin oxide (Sn
O ₂ ), titanium oxide (TiO ₂ ), tungsten oxide (W
O ₃ ), niobium oxide (Nb ₂ O ₅ ), cadmium sulfide (CdS),
Any material used in conventional light emitting compositions for low-speed electron beams, such as copper sulfide (Cu ₂ S), can be used. Also, (Zn
The mixing weight ratio of the 1-x, Cdx) S-based sulfide phosphor and the conductive substance may vary depending on the particle diameter of the conductive substance used, but the conventional low-speed electron composed of the mixture of the phosphor and the conductive substance is used. Almost the same as in the case of the light emitting composition for lines, a high brightness light emitting composition that can be put to practical use can be obtained when it is compounded in the range of 1:99 to 1: 1.

Figures 1 and 2 show (Zn _0.55 , Cd _0.45 ) S: Ag,
0.1% by weight of ZnO on the surface of Cl, Li phosphor converted to predetermined zirconia and zinc (Zn) (Zinc sulfate was used as a Zn compound, and this was once deposited as a hydroxide with an alkali. And then changed to ZnO by heat treatment)
And a (Zn _0.55 , Cd _0.45 ) S: Ag, Cl, Li phosphor mixed with 10% by weight of In ₂ O ₃ as a conductive substance to fluoresce the luminescent composition of the present invention. A fluorescent display tube used as a film was prepared, and when it was operated at an anode plate voltage of 30 V, (Zn _0.55 , Cd _0.45 ) S: Ag in the luminescent composition used for the fluorescent film of each fluorescent display tube. Between the amount of zirconia deposited on the phosphors, Cl and Li phosphors and the relative initial emission brightness of the fluorescent display tube (Fig. 1), and the relative emission brightness after the fluorescent display tube was lit for 1000 hours (the first (Fig. 2) respectively, and the emission luminance on the vertical axis is shown as a relative value with respect to the case where zirconia is not attached.

As is clear from FIGS. 1 and 2, (Zn _0.55 , Cd
_{When 0.45} ) S: Ag, Cl, Li zirconia is attached to the phosphor together with ZnO, the initial emission brightness of the luminescent composition using this gradually decreases with an increase in the amount of zirconia attached, but after 1000 hours of lighting The emission brightness of is higher than when zirconia is not attached (Zn _0.55 , Cd _0.45 ) S: Ag, Cl, Li phosphor only when the amount of zirconia adhered is about 1 wt% or less, and when lit for a long time The decrease in emission luminance with time is small. And, in particular, in that the decrease in initial brightness is kept within a practically acceptable range, and the decrease in emission brightness over time can be further suppressed (Zn _0.55 , Cd _0.45 ) S: Ag,
The amount of zirconia deposited on Cl and Li phosphors is 0.002-
More preferably, it is 0.1 wt%.

In addition, in the light emitting composition of the present invention, (Zn
_0.55 , Cd _0.45 ) S: Ag, Cl, Li When the amount of ZnO deposited on the phosphor is 0.005% by weight or less, or conversely 1% by weight or more, the amount of ZnO The emission brightness is low, and even if the amount of zirconia deposited on the (Zn _0.55 , Cd _0.45 ) S: Ag, Cl, Li phosphor is increased, the emission brightness after 1000 hours of lighting is not so high. No significant effect was observed.

In addition, in FIG. 1 and FIG. 2, it was produced from zinc sulfate.
ZnO (0.1 wt% Zn) and zirconia were adhered (Zn
_0.55 , Cd _0.45 ) S: Ag, Cl, Li Phosphors and In ₂ O ₃ (10% by weight of conductive material) A fluorescent display tube using a light-emitting composition comprising a mixture is used for its fluorescent film ( Zn _0.55 , Cd
_0.45 ) S: Ag, Cl, Li exemplifies the correlation between the amount of zirconia adhered in the phosphor and the initial emission brightness of the fluorescent display tube and the emission brightness after 1000 hours of lighting, but these correlations are (Zn1-x , Cd
x) As an S-based sulfide phosphor (Zn _0.55 , Cd _0.45 ) S: Ag, Cl,
When using a phosphor other than Li, when using a Zn compound other than zinc sulfate as the Zn compound, when using an oxide other than zirconia as the refractory oxide, In ₂ O ₃
When a conductive substance other than the above is used, it is almost similar to FIGS. 1 and 2 and is one component of the light emitting composition (Zn1−
x, Cdx) S-based sulfide phosphor has a high melting point oxide amount of 1 wt% or less, more preferably 0.002 to 0.1 wt%, and a Zn compound amount of 0.005 to 1 wt%
It was confirmed that in the case of the above range, a fluorescent display tube using the obtained light-emitting composition as a fluorescent film has a small decrease in emission luminance over time after long-time lighting and can maintain high luminance.

(Examples) Next, the present invention will be described by examples.

Examples 1 to 9 (Zn _0.55 , Cd _0.45 ) S: Ag, Cl, Li phosphor 100 g was put in 400 ml of pure water, and after stirring for about 10 minutes, 5.2 mg of zirconia sol as a high melting point oxide raw material (Nissan Chemical, ZrO ₂ content 19.1 wt%) was added dropwise and stirring was continued. Separately from this suspension, 230 mg of zinc sulfate {(ZnSO ₄ ) · 7H ₂ O} was dissolved in 50 ml of pure water, sufficiently stirred, and then added to the above suspension. After stirring for about 10 minutes, add NaOH little by little to this suspension,
The pH of this suspension was adjusted to about 9, and zinc hydroxide with zirconia was deposited on the surface of the phosphor. After dehydrating this suspension, it was placed in a heat-resistant container, baked for 24 hours in an electric furnace kept at 180 ° C, and then taken out.
A 1% by weight zirconia (ZrO ₂ ) and 0.1% by weight ZnO (Zn _0.55 , Cd _0.45 ) S: Ag, Cl, Li phosphor, converted to the amount of Zn, were obtained.

Then, the thus obtained (Zn _0.55 , Cd _0.45 ) S: Ag, Cl, L
90 parts by weight of the phosphor and 10 parts by weight of In ₂ O ₃ (conductive substance) having an average particle size of 0.24 μm were thoroughly mixed using a ball mill,
A luminescent composition [I] was produced.

Further, as the high-melting point oxide raw material, 0.001 wt% of zirconia sol was replaced with the raw material compounds shown in Table 1 and addition amounts of the respective high-melting point oxide raw materials (each oxide sol),
Similar to the light emitting composition [1], the light emitting composition [2] to
[9] was produced.

Separately, zirconium oxide (ZrO ₂ ) and ZnO were attached to the surface for comparison (Zn _0.55 , Cd _0.45 ) S: Ag, Cl,
Instead of Li phosphor, ZrO ₂ is not attached to the surface of each (Zn _0.55 , Cd _0.45 ) S: Ag, Cl, Li phosphor and Z on the surface.
No rO ₂ or ZnO attached (Zn _0.55 , Cd _0.45 ) S: Ag, C
Except for using the l, Li phosphor, the luminescent composition [1] to [9]
And the light emitting compositions [R-1] and [R-2]
(Conventional light emitting composition) was manufactured.

Then, the light emitting compositions [1] to [9], the light emitting composition [R-1] and the light emitting composition [R-2] are respectively used as fluorescent films by a known method to display fluorescent display tubes [1] to [9]. (Fluorescent display tube of the present invention), a fluorescent display tube [R-I] and a fluorescent display tube [R-2] (conventional fluorescent display tube) were produced, and these were turned on under a driving condition of an anode plate voltage of 30V, The emission brightness immediately after lighting (initial emission brightness) and the emission brightness after 1000 hours of lighting were measured, respectively, as shown in Table 1. The high melting point oxide (ZrO ₂ , Y ₂ O ₃ or CeO ₂ ) and oxidation were observed on the surface. Zinc (ZnO) and (Zn _0.55 , Cd _0.45 ) S: Ag, Cl,
Fluorescent display tubes ([1] to [9]) using a light-emitting composition composed of Li phosphor have only ZnO attached (Zn _0.55 , Cd
_0.45 ) Conventional fluorescent display tube using S: Ag, Cl, Li phosphor [R
The initial emission luminance was lower than that of -1], but depending on the amount of refractory oxide deposited on the (Zn _0.55 , Cd _0.45 ) S: Ag, Cl, Li phosphor used, refractory oxide may also be present. A conventional fluorescent display tube [R-
The initial luminance is higher than that of 2], and the emission luminance after 1000 hours of lighting is the same as that of the conventional fluorescent display tubes [R-1] and [R-.
Compared with 2], both were high, and the decrease in emission luminance with time was significantly suppressed, and the occurrence of uneven light emission of the fluorescent film was also reduced.

Examples 10 to 13 Each high melting point oxide raw material compound (each oxide sol) shown in Table 1 and the raw material compound shown in Table 2 in place of the addition amount and each high melting point oxide raw material (Sumitomo Cement In the same manner as in the light emitting compositions [1] to [9] of Examples 1 to 9 except that ultrafine particle oxide manufactured by Co., Ltd.) was used, each high melting point oxide and zinc oxide (shown in Table 2) were formed on the surface. ZnO) was attached (Z
n _0.55 , Cd _0.45 ) S: Ag, Cl, Li phosphors and luminescent compositions [10] to [13] composed of a mixture of In ₂ O ₃ were prepared.

Next, instead of the light emitting compositions [1] to [9], the light emitting composition [1
Examples 1 to 9 except that 0] to [13] are used as the fluorescent film.
The fluorescent display tubes [10] to [13] were manufactured in the same manner as the fluorescent display tubes [1] to [9] of Example 1, and the fluorescent display tubes were compared with Examples 1 to 9 prepared for comparison. The described fluorescent display tube [R-1] (conventional fluorescent display tube) is lit under the driving condition of the anode plate voltage of 30 V, and the luminescent brightness immediately after lighting (initial luminescent brightness) and the luminescent brightness after 1000 hours of lighting are displayed. The measurement results are shown in Table 2, respectively, and refractory oxide and zinc oxide (ZnO) were attached to the surface (Zn _0.55 , Cd _0.45 ).
Each of the fluorescent display tubes [10] to [13] using the light emitting composition including the S: Ag, Cl, Li phosphor has a lower initial emission brightness than the conventional fluorescent display tube [R-1]. However, the emission brightness after 1000 hours of lighting was high, the decrease in emission brightness over time was significantly suppressed, and the occurrence of uneven emission of the phosphor film was also reduced.

Examples 14 to 19 Instead of the raw materials shown in the raw material column of Table 1, each phosphor shown in the raw material column of Table 3 and zirconium oxide sol which is a high melting point oxide raw material (manufactured by Nissan Chemical Co., Ltd.) ), And zirconium oxide (ZrO ₂ ) and zinc oxide (Zn) on the surface in the same manner as in the light emitting compositions [1] to [9] of Examples 1 to 9.
O) and (Zn _0.22 , Cd _0.78 ) S: Ag, Cl, Na phosphor, (Zn _0.90 , Cd _0.10 ) S: Au, Al, Na phosphor and ZnS: Cu,
Each of the light emitting compositions [14] to [19] made of a mixture of each phosphor of Al and Na phosphors and In ₂ O ₃ was manufactured.

Separately, for comparison, ZrO ₂ and ZnO were attached to the surface of (Zn _0.22 , Cd _0.78 ) S: Ag, Cl, Na phosphor, (Zn _0.90 ,
Cd _0.10 ) S: Au, Al, Na phosphors and ZnS: Cu, Al, Na phosphors were replaced with neither ZrO ₂ nor ZnO on the surface (Zn _0.22 ,
Cd _0.78 ) S: Ag, Cl, Na phosphor, (Zn _0.90 , Cd _0.10 ) S: Au, A
Luminescent compositions [R-3] and [R- 4] and [R-
5] was produced.

Then, the fluorescent display tubes [14] to [19] and the fluorescent display tube [R] using the light emitting compositions [14] to [19] and the light emitting compositions [R-3] to [R-5] as fluorescent films, respectively. -3]
~ [R-5] (conventional fluorescent display tube) was produced, lighted under the driving condition of the anode plate voltage of 30V, and the light emission brightness immediately after lighting (initial light emission brightness) and the light emission brightness after 1000 hours of light emission were measured. As shown in Table 3, a comparison is made between fluorescent display tubes having the same phosphor composition in the light emitting composition constituting the phosphor film, and zirconium oxide (ZrO ₂ ) on the surface is compared.
The fluorescent display tubes [14] to [19] using a phosphor to which zinc oxide and zinc oxide (ZnO) are attached are conventional fluorescent display tubes [R-3] to
Although the initial light emission brightness was lower than that of [R-5], the light emission brightness after 1000 hours of lighting was high, the decrease in light emission brightness over time was significantly suppressed, and the light emission unevenness of the fluorescent film was also generated. It was decreasing.

(Effect of the invention) The luminescent composition of the present invention has an accelerating voltage of several KV or less, particularly 100 V.
It exhibits high-intensity emission under the following low-voltage voltage line excitation, and in particular, under long-time low-voltage electron beam excitation as compared with the conventional light-emitting composition composed of (Zn1-x, Cdx) S-based sulfide phosphor. It is useful for a fluorescent film of a fluorescent display tube because it has little advantage of decomposition and deterioration of emission luminance with time due to deterioration, and when it is used as a fluorescent film of a fluorescent display tube, uneven emission is unlikely to occur. .

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the amount of zirconia attached to the sulfide phosphor contained in the light emitting composition of the present invention and the initial emission brightness of a fluorescent display tube made of this light emitting composition. FIG. 2 is a graph showing the relationship between the amount of zirconia attached to the sulfide phosphor contained in the light emitting composition of the present invention and the emission brightness of a fluorescent display tube made of this light emitting composition after 1000 hours of lighting. Is.

Claims (1)

[Claims] 1. A composition formula is (Zn1-x, Cdx) S (where x is 0).
It is a number satisfying the condition of ≦ x ≦ 1. ) As a matrix, i) zirconium (Zr),
Refractory oxide consisting of at least one element selected from yttrium (Y), lanthanum (La), scandium (Sc), gallium (Ga), gadolinium (Gd), cerium (Ce) and samarium (Sm). And ii) zinc oxide (ZnO) or a compound of zinc (Zn) that can be converted into zinc oxide (ZnO) by heat treatment, and a mixture of a sulfide-based phosphor and a conductive material. Luminescent composition.