JP2013112739A - Method of manufacturing rare-earth doped sulfide phosphors - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a rare earth doped sulfide phosphors in which the reduction and sulfuration of a container used in the method is prevented and a problem of the deterioration of the container due to the reaction with flux in the use of the flux is solved while applying an efficient reduction sulfuration method of carbon disulfide.SOLUTION: In the method of manufacturing the rare earth doped sulfide phosphors expressed by general formula [AS:RE] in which A expresses an alkaline earth metal element and RE expresses a rare earth element, a step of reducing and sulfurating a precursor by carbon disulfide is executed to a mixture of the precursor with flux, wherein the precursor is prepared by mixing at least one kind of a rare earth doped oxide expressed by general formula [AO:RE], a rare earth doped carbonate expressed by general formula [ACO:RE] and an alkaline earth metal carbonate [ACO] with REOor REFwhich is a salt of rare earth. Therefore, the container in which the mixture is charged has a double structure comprising an inner container and an outer container, the inner container is made of graphite, and space between the outer container and the inner container is filled with an inert gas.

Description

  The present invention relates to a method for producing a rare earth-added sulfide phosphor suitable for a phosphor that emits high-intensity fluorescence with near-ultraviolet to blue light used in lighting, displays, and the like.

In recent years, with the development of blue LEDs and near-ultraviolet LEDs, development of white light-emitting elements that obtain white by combining these LEDs and phosphors is progressing. When a white light emitting element is produced using a blue LED, as described in Patent Documents 1, 2, and 3, a white light emitting element is obtained by combining a blue LED and a yellow phosphor.
However, white light composed of blue and its complementary color has poor color reproducibility and low color rendering, so a white light-emitting element called a three-wavelength type has been developed.

A light emitting element that emits blue light as a three-wavelength type white light emitting element, and a white light emitting element using a phosphor that emits green light and a phosphor that emits red light by receiving blue light emitted from the light emitting element (see Patent Document 4) See).
Examples of red phosphors that can be excited by blue light include CaAlSiN: Eu (Patent Document 5), (Sr, Ca) AlSiN (Non-Patent Document 1), Ca ₂ Si ₅ N ₈ , and Sr ₂ Si ₅ N _8. Nitride phosphors such as (Patent Document 6) and sulfide phosphors (Patent Document 7) such as CaS: Eu, SrS: Eu, and (Ca, Sr) S: Eu are known.

Sulfide phosphors have been known for a long time, and phosphors are produced by mixing calcium, strontium carbonate, sulfate and europium oxide as precursors and firing them in hydrogen sulfide.
For this reason, many attempts have been made to improve the characteristics of red phosphors.
For example, Patent Document 8 and Patent Document 9 describe red phosphors having calcium sulfide as a host center, Eu as a luminescent center, and Mn, Li, Ce, Gd and the like as sensitizers.

In addition, it is well known that a flux is used in the production of a phosphor. Patent Document 10 describes that a sulfur is sulfided in hydrogen sulfide at a temperature of about 1000 ° C., and then a flux is added to perform heat treatment. Further, Patent Document 11 describes a method in which sulfide and flux are mixed and fired.
However, in the sulfurization method using hydrogen sulfide, hydrogen sulfide is not only toxic, but also a malodorous substance and an unstable substance. There are also problems such as incurring a decline in

In order to solve these problems, a reductive sulfidation method for oxides and carbonates using carbon disulfide has been developed as a sulfidation method (Patent Document 12, Non-Patent Document 2).
In addition, it has been known that, when flux is added, sulfiding and flux firing are separately performed twice.

Japanese Patent Laid-Open No. 10-093146 Japanese Patent Application Laid-Open No. 10-065221 Japanese Patent Laid-Open No. 10-242513 JP 2000-244021 A JP 2006-008721 A JP 2006-152296 A JP 56-82876 A JP 2002-80845 A JP 2003-41250 A JP 2005-509081 A JP 2005-146190 A JP 2009-212264 A

Hiromu Watanabe and Naoto Kijima, Journal of Alloys and Compounds, 475, 2009, p. 434. Valery Petrykin and Masato Kakihana, Journal of the American Ceramic Society, 92, 2009, [S1] S27-S31.

The method of sulfiding oxides and carbonates using carbon disulfide has the advantage that it can be sulfided at a lower temperature and in a shorter time than when hydrogen sulfide is used because of its strong reducing power. When decomposed, the quartz tube or alumina tube generally used in tubular furnaces is reduced and sulfided due to its strong reducing power, and the generated sulfide is mixed into the phosphor.
Mixing chlorides and fluorides and sulfiding is efficient because the number of firings is reduced, but the chlorides and fluorides evaporate, so the quartz tube may be devitrified and damaged. There is also the problem of reacting with.

  As a result of intensive studies to solve the various technical problems, the present inventors have adopted an efficient carbon disulfide reductive sulfidation method, and in this method, a container made of carbon is optimal. It has been found that the atmosphere around the carbon container is made inert gas so that the carbon is not oxidized, thereby preventing the reduction and sulfidation of the container and solving the problem of deterioration due to the reaction with the flux when using the flux. The invention has been completed.

A first invention of the present invention is a method for producing a rare earth-added sulfide phosphor represented by a general formula [AS: RE], wherein A is an alkaline earth metal element, and RE is a rare earth element. At least one of a rare earth-added oxide represented by A _X O _Z : RE], a rare earth-added carbonate represented by the general formula [A _X CO _{3 + Z} : RE], and an alkaline earth metal carbonate [ACO ₃ ]; In the step of reducing and sulfiding a precursor mixed with RE ₂ O ₃ or REF ₃ which is a rare earth salt with carbon disulfide, the reduction and sulfidation is performed on the mixture of the precursor and the flux. The container into which the mixture is put in the case of reductive sulfidation has a double structure composed of an inner container and an outer container, and the inner container is made of graphite, and an inert gas is filled between the outer container and the inner container. It is characterized by being A method for producing a rare earth doped sulfide phosphor.

  In the second invention of the present invention, the flux in the first invention is at least one selected from alkali metal chlorides, bromides, fluorides, alkaline earth metal chlorides, bromides, and fluorides. This is a method for producing a rare earth-added sulfide phosphor.

  The third invention of the present invention is characterized in that the alkaline earth metal element A in the first and second inventions is composed of one or more selected from Ca and Sr, and the rare earth metal element RE is Eu. This is a method for producing a rare earth-added sulfide phosphor.

The present invention relates to a rare earth-added oxide represented by the general formula [A _X O _Z : RE], a rare earth-added carbonate represented by the general formula [A _X CO _{3 + Z} : RE], an alkaline earth metal carbonate (ACO ₃ ) In a reductive sulfidation process in which a precursor mixed with at least one kind of rare earth salt RE ₂ O ₃ or REF ₃ and a flux are heat-treated in an inert gas containing carbon disulfide, the reaction vessel has a double structure. The inner container through which carbon disulfide flows is made of graphite, and an inert gas is filled between the inner container and the outer container. According to the present invention, Without causing damage to the reaction vessel by carbon disulfide or flux vapor, and without using toxic hydrogen sulfide, the phase purity is high, and high-luminance red light-emitting phosphor particles can be stably obtained. , Production stability, safety, is intended to achieve the high-quality, industrially remarkable effects.

The Ar gas is an explanatory diagram showing an example of a method to include carbon disulfide (CS _2). It is a figure which shows the structure of the core tube of the tubular furnace to be used, (A) is a conventional core tube, (B) is a figure which shows the core tube of the double tube structure which used the graphite tube for the inner tube of this invention, (C) is a figure which shows the core tube which has another structure which has a graphite tube in an inner tube. It is a figure which shows an example of a structure of the box furnace using a graphite container. Generating at equilibrium in the degradation of CS ₂ was calculated from the reaction formula (1) is a diagram showing a change in the percentage of S _2. It is a figure which shows Gibbs free energy change ((DELTA) G) in Reaction formula (2). It is a figure which shows the result of having calculated Gibbs free energy change (DELTA) G in Reaction formula (3)-(6). It is a figure which shows the result of having calculated the equilibrium constant K in Reaction formula (3)-(6). In Scheme (3) to (6), is a diagram showing a calculation result of the free energy change ΔG Gibbs when using _Al 2 _{O 3} instead of SiO ₂ (alumina). It is a figure which shows the emission spectrum of Example 1, 2, 5, 6.

In general, in the production of a compound using a reducing reaction gas, a furnace container that does not react with a reaction gas or a generated gas is used.
In a reducing atmosphere, a metallic container can be used. However, since metals such as iron, tungsten, and molybdenum often sulfidize, an inert gas containing carbon disulfide generated by the method shown in FIG. 1 is used. In the case of carrying out reductive sulfidization by flowing, a tubular furnace using a quartz tube, an alumina tube or the like as a furnace core tube is conventionally used as shown in FIG.

FIG. 1 is a schematic diagram showing a carbon disulfide (gas) generator, wherein 1 is a carbon disulfide generator, 10 is a water bath, and carbon disulfide {liquid} is applied to a water bath 10 filled with water 11 of appropriate temperature. The beaker 12 is immersed in a bath to control the temperature, an inert gas (Ar gas in FIG. 1) is blown into the carbon disulfide (liquid) as a carrier gas, and gaseous carbon disulfide is sent out.
FIG. 2A is a cross-sectional view showing an outline of a core tube portion of a conventionally used tubular furnace, 21 is a conventional quartz tube, 23 is a quartz sliding lid, and is placed in the quartz tube 21. A carrier gas (Ar) containing carbon disulfide (CS ₂ ) is passed through the sample.

Reductive sulfidation of oxides and carbonates using carbon disulfide has stronger reducing power than hydrogen sulfide, and can be sulfided at a low temperature and in a short time.
This is not only because of the strong reducing power of carbon disulfide, but also as shown in the following reaction formula (1), carbon disulfide decomposes into carbon and sulfur at a high temperature, and carbon fine particles adhere to the raw material, which is used for reduction. This is to contribute.

The Gibbs free energy change (ΔG) and the equilibrium constant K are calculated from the above reaction formula (1) using thermodynamic calculation software (“HSC chemistry ver4.1” manufactured by Autotec Research Oy.), And [S ₂ (g )] / [CS ₂ (g)] is shown in FIG.

FIG. 4 shows that CS ₂ is decomposed by 10% at 600 ° C. and 15% or more at 1000 ° C. In this decomposition, sulfur (S ₂ (g)) moves to the low temperature part and precipitates, but carbon (C) adheres to the high temperature part. Further, when carbon monoxide is present in the system, the reaction of the following reaction formula (2) may occur.

The calculation result of ΔG of this reaction is shown in FIG.
From the calculation results, if CO is present, ΔG becomes negative at 775 ° C. or lower, and C is generated. That is, if the CO generated in the sulfurization reaction with CS _2. In this case, C is generated when the temperature is lowered while flowing CS ₂ with CO remaining in the pipe.

When the CS ₂ reduction sulfidation is actually performed at 900 ° C. or higher for a long time, the sample becomes black. In the XRD measurement of this sample, no diffraction peak other than sulfide is detected. Further, impurities such as EPMA are not detected. Further, the black color disappears when firing in air or carbon dioxide.
From these facts, it seems that the blackening of the sulfide is due to the adhesion of carbon.
Therefore, when CS ₂ is subjected to reductive sulfidation using a quartz tube, it is necessary to take into account C generated for the above reasons, particularly when it is repeatedly used.
Next, the calculation results of Gibbs free energy change ΔG and equilibrium constant K using the following reaction formulas (3) to (6) are shown in FIGS.

The results of calculating the Gibbs free energy (ΔG) change and the equilibrium constant K using the above reaction formulas (3) to (6) are shown in FIGS.
From the change in ΔG, the reaction of the above reaction formula (6): “SiO ₂ + C + CS ₂ (g) = SiS ₂ + 2CO (g)” is most likely to occur at 800 ° C. or higher, and the value becomes negative at 1300 ° C. or higher.
This is 100 ° C. lower than when there is no carbon. The equilibrium constant K at 1000 ° C. in this case was calculated to be 0.00247.
From this, it can be seen that when [CO (g)] is 4.8%, ([CO (g)] ² / [CS ₂ (g)] = 0.242) or less, the reduction sulfurization proceeds.

Moreover, the result of having performed the same calculation regarding alumina is shown in FIG.
ΔG becomes negative at 1200 ° C. or higher when carbon is present. This was lower by 100 ° C. than when no carbon was present, and it was found that when solid carbon was present, it was easily reduced and sulfided.
Actually, when CS ₂ was supplied using a quartz tube and reduced and sulfided at 950 ° C. for 2 hours, cotton-like SiS ₂ was precipitated in the tube. Further, when alumina was put in a quartz tube and CS ₂ was flowed and reduced and sulfidized at 950 ° C. for 2 hours, a dome-shaped protrusion was generated on the surface.
From these points, it can be seen that the quartz tube and the alumina tube are not suitable for a production method in which carbon disulfide is used for reduction sulfidation at 800 ° C. or higher. In particular, repeated use at 950 ° C. or higher is not preferable because foreign matter such as SiS ₂ generated from the quartz tube may be mixed into the phosphor.

Therefore, graphite can be considered as a material that can be used at high temperatures, but it is optimal for flowing an inert gas containing carbon disulfide. However, since graphite reacts with oxygen and burns, it is necessary to shut off the container from the atmosphere.
As a method of blocking the graphite container from the atmosphere, it is effective to use a double structure of the graphite container as an inner container and an outer (atmosphere side) container.

The outer container (atmosphere side) of the double structure can be used without limitation, such as quartz, alumina, or metal container, but if the outer container and the graphite inner container are brought into contact, the outer container on the atmosphere side If it is made of metal, it may react to form a carbide, and if it is made of oxide, the oxide container may be reduced.
Therefore, it is necessary that there is a space between the graphite inner container and the atmosphere side container.
However, if there is oxygen in the space between the graphite inner container and the atmospheric outer container, the graphite inner container oxidizes, so it is necessary that the space portion does not contain oxygen, and inert gas is introduced into the space portion. This can be achieved by flowing.

As an example of such a reducing sulfide apparatus, FIGS. 2B and 2C show a sectional view of a core tube portion of a tubular furnace using a graphite inner vessel (core tube), and the structure thereof is shown.
2B and 2C, 20 is a graphite tube (inner vessel: inner core tube), 22 is a quartz tube (outer vessel: outer core tube), 24 is a carbon sheet, 25 is a sulfur reservoir, and 26 is a flange. It is.
2 (B) and 2 (C) both adopt a double tube structure, using a graphite tube 20 for the inner vessel (inner core tube) and using a quartz tube 22 for the outer vessel (outer core tube), An inert gas (Ar is used in the figure) is circulated between the outer containers so as to be filled.
Furthermore, as a furnace form other than the tubular furnace, a box furnace using a graphite container as shown in FIG. 3 as an inner container may be used. In FIG. 3, 30 is a box furnace, 31 is a graphite vessel (inner vessel), 32 is an outer vessel (quartz / carbon sheet composite), and 36 is a heater.

By using the production method of the present invention, rare earth-added sulfide fluorescence represented by the general formula [AS: RE], wherein A is one or more alkaline earth metal elements of Ca and Sr, and RE is rare earth Eu. The body can be made.
Specifically, a rare earth-added oxide of the general formula [A _X O _Z : RE], at least one of the general formula [A _X CO _{3 + Z} : RE], an alkaline earth metal carbonate (ACO ₃ ), and a rare earth salt A precursor in which RE ₂ O ₃ or REF ₃ is mixed is reduced and sulfided using carbon disulfide.
When a rare earth-added oxide or rare earth-added carbonate in which rare earth elements are uniformly distributed is used as a precursor raw material to be used, reductive sulfidization at a low temperature becomes possible. On the other hand, a mixture of alkaline earth metal carbonate (ACO ₃ ) and a rare earth salt such as RE ₂ O ₃ or REF ₃ as a raw material may be used as a precursor, and the phosphor may be produced by reduction-sulfurization. .

Furthermore, in the method for producing a sulfide phosphor of the present invention, firing using a flux is effective for reducing the temperature and shortening the reduction sulfur reaction.
The flux used, KCl and NaCl, BaCl ₂ and SrCl _2, CaCl alkali metal or alkaline earth metal chlorides, such as, KBr or _NaBr, BaBr _2, bromides such as SrBr _2, CaBr 2, BaF 2 and SrF ₂ , fluorides such as CaF ₂ can be suitably used.

In the method for producing a sulfide phosphor of the present invention, since the flux is melted and used, the heat treatment temperature is preferably above the melting point of the flux and below the boiling point, and the flux does not react with the phosphor to form a compound. desirable. From these points, it is particularly preferred to use chlorides such as KCl and SrCl _2.
If the flux is used above its melting point, it may evaporate and react with the container. Therefore, when using alkali metal or alkaline earth metal chloride as a flux, if a quartz tube is used as an inner container, it will react and devitrification will occur. The quartz tube may be damaged.
Therefore, as in the present invention, in the manufacturing method using a graphite container as the inner container, there is almost no damage due to the flux, no foreign matter is mixed into the generated sulfide phosphor, and it can be used stably and repeatedly. Is also a feature.

  Hereinafter, the present invention will be described using examples.

Europium oxide (3N: Eu ₂ O ₃ manufactured by Furuuchi Chemical Co., Ltd.) 0.005 mol (1.9126 g) was completely dissolved in nitric acid (60% manufactured by Kanto Chemical Co., Ltd.), and the solution was evaporated. It was dried to obtain Eu nitrate (Eu nitrate). Distilled water was added to this Eu nitrate and the resulting solution was dissolved in 100 ml to prepare an aqueous solution with an Eu concentration of 0.1 mol / liter.

Next, 2.4595 g of strontium carbonate (3N, manufactured by Kanto Chemical Co., Inc.) was added to a beaker containing 50 ml of distilled water, and the mixture was stirred at a set temperature of the hot stirrer of 80 ° C. and a rotation speed of 150 rpm. In this stirred state, 16 g of citric acid was added and stirred for 1 hour to prepare a solution in which strontium carbonate was completely dissolved. 0.56 ml of an aqueous solution of Eu nitrate (0.1 mol / liter) was added to the solution, and the mixture was stirred at 80 ° C. for 2 hours. 12.7 g of propylene glycol was added, and the mixture was stirred at 120 ° C. for 3 hours to cause gelation.
The ratio of metal moles (Sr + Eu): citric acid: propylene glycol is 1: 5: 10. The Eu concentration (Eu / (Sr + Eu)) is 0.2%.

Next, the gel body was put in a mantle heater placed in a draft, heated to 450 ° C., and the gel body was thermally decomposed to prepare an oxide precursor. Further, this was pulverized with a mortar to prepare an oxide precursor powder.
The obtained oxide precursor powder was baked at 750 ° C. for 2 hours to burn away residual organic substances.

To 0.3960 g of the obtained powder, 0.0442 g of potassium chloride (KCl) was added, and this was pulverized in a mortar. A tubular furnace using a furnace core tube in which a graphite tube is placed in a quartz tube shown in FIG. 2 (B) under Ar circulation through liquid carbon disulfide by the method shown in FIG. Then, heat treatment was performed at 925 ° C. for 1 hour to perform reduction sulfidation to produce Eu-added SrS sulfide. In FIG. 2B, 20 is an inner core tube (graphite tube), 22 is an outer core tube (quartz tube), and 24 is a carbon sheet.
Ar flow rate is 50 ml / min for 10 minutes from the start of heat treatment, then 10 ml / min until the temperature reaches 460 ° C., 20 ml / min until the temperature reaches from 460 ° C. to 925 ° C. The flow rate was adjusted to 10 ml / min for a total of 4 hours and 20 minutes until the furnace temperature reached 40 ° C.

2.7678 g of calcium carbonate (3N manufactured by Kanto Chemical Co., Inc.) was added to a beaker containing 100 ml of distilled water, and the hot stirrer was set at a set temperature of 80 ° C. and a rotation speed of 150 rpm. To this stirred state, 31.878 g of citric acid was added and stirred for 1 hour to prepare a solution in which calcium carbonate was completely dissolved. 0.277 ml of an aqueous solution of Eu nitrate (0.1 mol / liter) was added thereto, and the mixture was stirred at 80 ° C. for 2 hours. To this was added 21.06 g of propylene glycol, and the mixture was stirred at 120 ° C. for 3 hours to gel.
The ratio of moles of metal (Ca + Eu): citric acid: propylene glycol is 1: 6: 10. The Eu concentration (Eu / (Ca + Eu)) is 0.2%.

Next, the gel body was put in a mantle heater placed in a draft, heated to 450 ° C., and the gel body was pyrolyzed to prepare an oxide precursor. Furthermore, this was pulverized in a mortar to prepare an oxide precursor powder, and the obtained oxide precursor powder was baked at 750 ° C. for 2 hours to burn off residual organic substances. 0.0382 g of potassium chloride (KCl) was added to 0.3071 g of the obtained powder, and this was pulverized in a mortar.
This pulverized product was reduced and sulfided under the same conditions as in Example 1 to produce Eu-added CaS sulfide.

  An Eu-added SrS sulfide was produced in the same manner as in Example 1 except that the maximum retention temperature of reduced sulfurization in Example 1 was 950 ° C.

  An Eu-added CaS sulfide was produced in the same manner as in Example 2 except that the maximum retention temperature of reduced sulfidation in Example 2 was 950 ° C.

  Eu was added in the same manner as in Example 2 except that Sr carbonate and Ca carbonate were added so that the maximum retention temperature of reduced sulfide in Example 2 was 950 ° C. and the ratio of Sr to Ca was 85:15 (Sr , Ca) S sulfide was prepared.

  Eu addition (Sr , Ca) S sulfide was prepared.

  Eu-added (Sr, Ca) S sulfide was produced in the same manner as in Example 5 except that the flux was changed to strontium chloride.

  Eu-added (Sr, Ca) S sulfide was produced in the same manner as in Example 6 except that the flux was changed to strontium chloride.

Calcium carbonate, strontium carbonate and europium oxide powders were weighed to a molar ratio of 0.499: 0.499: 0.002 and mixed in an agate mortar.
To this mixed powder, 15% by weight of potassium chloride was added and further mixed to obtain a raw material powder, which was put into a graphite container and Eu-added (Sr, Ca) S sulfide was produced in the same manner as in Example 1.

(Comparative Example 1)
Eu-added SrS sulfide was prepared in the same manner as in Example 1 except that potassium chloride was not added.

(Comparative Example 2)
An Eu-added CaS sulfide was produced in the same manner as in Example 2 except that potassium chloride was not added.

(Comparative Example 3)
Eu-added SrS sulfide was produced in the same manner as in Example 1 except that potassium chloride was not added and the maximum retention temperature of reduced sulfurization was 800 ° C.

(Comparative Example 4)
An Eu-added CaS sulfide was produced in the same manner as in Example 2 except that potassium chloride was not added and the maximum retention temperature for sulfurization was 800 ° C.

(Conventional example 1)
Eu-added SrS sulfide was produced in the same manner as in Example 1 except that a synthetic quartz tube was used instead of the graphite tube in Example 1.
After reductive sulfidation, a flocculent substance adhered to the quartz tube.

(Conventional example 2)
An Eu-added CaS sulfide was prepared in the same manner as in Example 2 except that a synthetic quartz tube was used instead of the graphite tube in Example 2.
After reductive sulfidation, a flocculent substance adhered to the quartz tube, and when the sulfurized sample black light was irradiated, the surface emitted green light. This luminescence was not visible when the sample was ground in a mortar.

(Conventional example 3)
Eu-added SrS sulfide was produced in the same manner as in Example 1 except that an alumina container was used instead of the graphite container in Example 1.
Discoloration of the alumina container occurred after sulfurization, and when the black light was irradiated, the discolored portion emitted green light. Further, when the alumina container was repeatedly used, irregularities were generated on the surface.

  In addition, when a firing test with potassium chloride is performed using a synthetic quartz tube in Conventional Example 1, fogging occurs inside the tube after three sulfidation tests, and further reduction sulfidation results in a grainy shape from the quartz tube. Quartz peeled off.

(Conventional example 4)
An Eu-added CaS sulfide was produced in the same manner as in Example 2 except that a synthetic quartz tube was used instead of the graphite tube of Example 1.
After reductive sulfidation, a flocculent substance adhered to the quartz tube.

  The prepared samples were evaluated by measuring the following items.

[Brightness evaluation]
The evaluation of the brightness was performed using YAG: Ce (P61: manufactured by Kasei Opto), which is well known as a yellow phosphor for LED, as a reference material, and Examples 1 to 9, Comparative Examples 1 to 4, and The comparison was made with Eu-added sulfide phosphors produced in Conventional Example 1 to Conventional Example 4.
Table 1 summarizes the results of measuring the emission spectrum and comparing the peak intensity and the emission wavelength.
The measured emission spectra of Examples 1, 2, 5, and 6 are shown in FIG.

When comparing the peak intensities of Examples 1 to 9 produced by the production method of the present invention and Comparative Examples 1 to 4 where the production conditions were not satisfied, the reduced sulfurization temperature was 900 ° C. or higher, and the flux was It can be seen that the luminance is greatly improved by adding KCl, which is equal to or higher than YAG: Ce.
In the Eu-added CaS of Comparative Example 2, it is considered that the brightness of the sample was also reduced because the sample was blackened. At 800 ° C., there was no blackening of the sample, so the luminance of Eu-added CaS was improved, but the temperature was insufficient and the crystallinity was not sufficient. Eu-added SrS lacks brightness unless KCl is added.

In Conventional Example 1 to Conventional Example 4, the luminance of Conventional Example 2 and Conventional Example 3 in which the quartz tube or the alumina container and the sulfide reacted is significantly reduced.
In the conventional example 1 and the conventional example 4 that did not react, the luminance was relatively high, but a foreign substance presumed to be SiS ₂ was generated and could be mixed into the phosphor. It turns out that the pipe is broken, and there is a problem in terms of quality and safety.

DESCRIPTION OF SYMBOLS 1 Carbon disulfide generator 10 Water bath 11 Water 12 Beaker 20 Graphite tube 21 Quartz tube (conventional single tube core tube)
22 Quartz tube (outer container)
23 Quartz sliding lid 24 Carbon sheet 25 Sulfur reservoir 26 Flange 30 Box furnace 31 Graphite container (inner container)
32 Outer container (quartz / carbon sheet composite)
36 Heater

Claims (3)

It is represented by the general formula [AS: RE], wherein A is an alkaline earth metal element and RE is a rare earth element-added sulfide phosphor,
At least one of a rare earth-added oxide represented by the general formula [A _X O _Z : RE], a rare earth-added carbonate represented by the general formula [A _X CO _{3 + Z} : RE], and an alkaline earth metal carbonate [ACO ₃ ]. A precursor obtained by mixing one kind and RE ₂ O ₃ or REF ₃ which is a rare earth salt,
In the process of reducing and sulfiding with carbon disulfide,
The reduced sulfidation is performed on the mixture of the precursor and the flux;
The container in which the mixture is put in the reduction sulfurization has a double structure composed of an inner container and an outer container, and the inner container is made of graphite, and an inert gas is filled between the outer container and the inner container. A method for producing a rare earth-added sulfide phosphor.   2. The rare earth additive according to claim 1, wherein the flux is at least one selected from an alkali metal chloride, bromide, fluoride, alkaline earth metal chloride, bromide, and fluoride. A method for producing a sulfide phosphor. The alkaline earth metal element A is composed of one or more selected from Ca and Sr,
The method for producing a rare earth-added sulfide phosphor according to claim 1 or 2, wherein the rare earth metal element RE is Eu.

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