JPH069204A - Preparation of high purity metal sulfide for phosphor base material - Google Patents

Abstract

PURPOSE: To produce a high purity metallic sulfide having a uniform particle size distribution and excellent in fluorescent efficiency by blending a sulfite or a thiosulfate with sulfur powder and a metallic compd. in a prescribed ratio and heating the resultant mixture at a prescribed temp. for a prescribed time.

CONSTITUTION: A mixture of 1-5 mol sulfite or thiosulfate (e.g. sodium sulfite or sodium thiosulfate), 1-20 mol sulfur powder and 1 mol metallic compd. (e.g. sulfate, halide or oxide of a metal selected from the group consisting of prim. transition metals, alkaline earth metals and rare earth metals) is comminuted and heated at 300-800°C for 2-6 hr to obtain particles of the objective metallic sulfide (e.g. ZnS, CaS, Y₂O₂S, Gd₂O₂S) having a relatively uniform particle size distribution of 6-8 μm as a simple compd. in high purity. The fluorescent efficiency of a phosphor obtd. from the metallic sulfide is comparable to that of the conventional phosphor or is higher than that by about 15%.

COPYRIGHT: (C)1994,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a metal sulfide useful as a base material for various phosphors in high purity.

[0002]

2. Description of the Related Art Conventionally, zinc sulfide (Z
nS), yttrium oxysulfide (Y ₂ O ₂ S), calcium sulfide (CaS) and other metal sulfides are used. As a method for producing a metal sulfide for such an application, an aqueous solution method, a flux high temperature reaction method, a gas high temperature reaction method and the like are known.

Electrochem.Technol., Vol.6, No.7-8, P
246-251 (1968) and J. Am. Ceram. Soc., Vol. 73 (2), P245.
~ 250 (1990) describes an aqueous solution method in which hydrogen sulfide gas is passed through a zinc ion solution or a sodium sulfide solution is added to precipitate zinc sulfide, and this method is an industrially important method. Is. However, in this aqueous solution method, the size of the obtained zinc sulfide particles is within the preferable range, and in order to produce zinc sulfide with high fluorescence efficiency in a high yield, the zinc ion concentration in the reaction solution, pH, The concentration of impurities must be controlled by strictly adjusting the supply rate and stirring rate of hydrogen sulfide gas or sodium sulfide solution. In addition to this step, filtration, washing and drying are further required, so that the number of steps is increased and the chance that impurities are mixed in the final product is increased.

The high temperature gas reaction method is a method of producing a metal sulfide by reacting at high temperature in an atmosphere of a gas such as hydrogen sulfide or carbon disulfide that produces sulfur vapor at high temperature.
It is also used industrially. This method is described in US Pat.
No. 418,246. However, the high-temperature reaction method using hydrogen sulfide can obtain a high-purity sulfide, but must use a high-purity gas,
Further, the yield is low, which is economically unfavorable. Further, in the high temperature reaction method using carbon disulfide, a polymer of carbon disulfide may be formed at a high temperature, or carbon disulfide may be decomposed to generate carbon powder, and these black by-products emit fluorescence. The obtained metal sulfide is not preferable as a raw material for the phosphor because it has an absorbing property.

The flux high-temperature reaction method is a technique for producing mainly calcium sulfide (CaS), yttrium oxysulfide (Y ₂ O ₂ S) and the like by using a mixture of sodium carbonate and sulfur as a flux (J. Electrochem.Soc., Vol.130 (2), P432〜
437 (1983)). However, since the metal sulfide obtained by this method contains carbon powder or a polymer of carbon disulfide as an impurity, like the above-described high temperature gas reaction method,
The obtained metal sulfide is not preferable as a raw material for a phosphor because it has a property of absorbing fluorescence. In the above method, the reaction in which a carbon powder or a polymer of carbon disulfide is produced is as follows. The carbonate used as a raw material is
First, it reacts with sulfur to produce carbon monoxide and carbon dioxide. At this time, if sulfur is present, the following side reaction occurs.

2CO → CO ₂ + C (1) CO + 1 / nS _n → OCS (2) C + S ₂ → CS ₂ (3) OCS + CO → SO ₂ + 2C (4) 2CO ₂ + 1 / 2S ₂ → SO ₂ + 2CO (5) CO ₂ + 1 / 2S ₂ → SO ₂ + C (6)

As shown in the above reaction formula, carbon monoxide produces carbon and carbon dioxide by the reaction (1), while it reacts with sulfur by the reaction (2) to produce OCS. The carbon produced in the reaction (1) will produce carbon disulfide by the reaction (3), and the carbon disulfide will be polymerized at a high temperature to produce a black carbon disulfide polymer (Physic
a Status Solidi, 32. P749 (1969)). In addition, carbon dioxide is easily reduced by sulfur vapor at high temperature and reacts (5)
As shown in, it is converted to carbon monoxide, and the reaction (6)
It is converted to carbon as shown in. And reaction (2)
The OCS gas generated in step 2 produces carbon by the reaction (4). Depending on the conditions, the produced carbon is converted into carbon disulfide or a carbon disulfide polymer again by the reaction (3). This addition product, carbon or carbon disulfide polymer, absorbs the fluorescence emitted by the phosphor and lowers the fluorescence efficiency, so it is necessary to remove it, but an appropriate solvent or chemical reaction for removing them is required. Therefore, it is difficult to remove the carbon once produced and the carbon disulfide polymer.

[0008]

DISCLOSURE OF THE INVENTION An object of the present invention is to produce a high-purity metal sulfide useful as a base material for a phosphor, which does not produce carbon or carbon disulfide polymer which deteriorates the fluorescence efficiency. To provide.

[0009]

According to the present invention, 1 to 5 mol of a sulfite or thiosulfate, 1 to 20 mol of a sulfur powder and 1 mol of a metal compound are mixed and crushed, and then 300 to
It is a method for producing a high-purity metal sulfide for a phosphor substrate, which comprises heating at 800 ° C. for 2 to 6 hours.

The present invention will be described in detail below. As the sulfite or thiosulfate used in the present invention, sodium sulfite, sodium thiosulfate, potassium sulfite and potassium thiosulfate are preferable. Examples of the metal compound used in the present invention include first transition metals such as zinc; Ca, Mg, Ba, Sr.
A single alkaline earth metal such as Ca-Mg, Ca-Sr,
Metals consisting of two alkaline earth metals capable of forming solid solution sulfides such as Ca-Ba, Mg-Sr, Mg-Ba, Sr-Ba; and rare earths such as Y, Gd, La, Nd and Eu. Sulfates, halides or oxides of metals selected from the group consisting of metals are preferred.

The metal sulfide which is the object of the present invention is a sulfide or oxysulfide of the metal used as the above-mentioned metal compound, for example ZnS, CaS, Y ₂ O ₂ S, G.
Examples thereof include d ₂ O ₂ S. In the present invention,
The reaction of the metal compound with sulfite (or thiosulfate) and sulfur powder is described below.

Sulfite reacts with sulfur powder to give 200
At ˜600 ° C., thiosulfate is produced, and this thiosulfate reacts with the metal compound to produce metal sulfide and alkali metal sulfate. At this time, if an excessive amount of sulfite and sulfur powder is used, an alkali metal sulfide and a sulfate are produced together. As an example, the reaction formulas of the metal oxide with sodium sulfite and sulfur powder, the reaction of the metal oxide with thiosulfate, and the reaction formulas of sodium sulfite with sulfur powder are shown below.

CaO + Na ₂ SO ₃ + S → CaS + Na ₂ SO ₄ (7) CaO + Na ₂ S ₂ O ₃ → CaS + Na ₂ SO ₄ (8) Y ₂ O ₃ + Na ₂ SO ₃ + S → Y ₂ O ₂ S + Na ₂ SO ₄ (9) ) ZnO + Na ₂ SO ₃ + S → ZnS + Na ₂ SO ₄ (10) Na ₂ SO ₃ + S → Na ₂ S ₂ O ₃ (11) 4Na ₂ S ₂ O ₃ → Na ₂ S ₅ + 3Na ₂ SO ₄ (12) 4Na ₂ SO ₃ → Na ₂ S + 3Na ₂ SO ₄ (13)

The alkali metal sulfides obtained in reactions (12) and (13) act as a flux for the grain growth of alkaline earth metal sulfides, transition metal sulfides or rare earth metal sulfides. According to the reaction formulas (7) to (10), the reaction substance,
For example, sodium sulfite (or sodium thiosulfate) and sulfur powder are stoichiometric amounts, ie 1 mole of CaO.
For each one must be used in an amount of 1 mol,
In practice, the reaction is carried out at 400 ° C or higher, so in consideration of sulfur evaporation at high temperature and sulfur loss due to thermal decomposition of sulfite (or thiosulfate), excess amounts of these raw materials should be used. I have to.

As a result of the reaction, in order to grow the obtained particles of calcium sulfide to a desired size, a predetermined amount of flux is required. For this purpose, a larger amount of sulfite (or thiosulfate) is required. ) And sulfur powder must be replenished. The amount of sulfite (or thiosulfate) and sulfur powder that must be replenished will depend on the size and morphology of the reaction vessel and electric furnace used and the amount of reactants. Considering the above matters, 1 to 5 mol of sulfite (or thiosulfate) is added to 1 mol of metal compound.
And a composition of 1 to 20 mol of sulfur powder is preferred. When thiosulfate is used instead of sulfite, the amount of sulfur powder can be reduced to 1/2.

The sulfurization reaction of the metal compound is 300 to 800.
It can be performed within 2 to 6 hours at ℃, but at 600 ℃ 2
It is preferably completed within 4 hours. If water is contained in the sulfite salt (or thiosulfate salt) and the metal compound that is a reactant, an undesirable side reaction occurs. That is, the water content may participate in the reaction, resulting in loss of sulfur powder and decomposition of sulfides. Therefore, it is preferable to increase the reaction temperature after preheating the reaction material at 100 to 200 ° C. and drying it in advance.

[0017]

According to the present invention, metal sulfide particles having a relatively uniform particle size distribution of 6 to 8 μm can be obtained as a single compound in high purity, and a phosphor obtained from this metal sulfide is obtained. The fluorescence efficiency of is equal to or better than that of the conventional phosphor by about 15%.

[0018]

【Example】

Hereinafter, the present invention will be described in more detail with reference to Examples. Example 1 4.000 g of calcium carbonate was placed in an alumina crucible,
Using an electric furnace, it was baked at 900 ° C. for 2 hours to obtain calcium oxide. This calcium oxide was thoroughly mixed with 7.562 g of anhydrous sodium sulfite and 12.83 g of sulfur powder in a mortar to prepare a reaction mixture.

This reaction mixture was placed in an alumina crucible with a lid and heated at 600 ° C. for 2 hours to cause a reaction, and then the temperature in the electric furnace was cooled to room temperature. Next, in the obtained reaction product, water-soluble sodium sulfate, sulfide, thiosulfate, sulfite, etc. are dissolved in ice water,
The remaining calcium sulfide powder which had been removed was further washed with cold distilled water (7 ± 2 ° C.) three times. This was dried at 110 ± 10 ° C. for 2 hours to obtain 2.783 g of the desired product. As a result of comparison between the X-ray diffraction analysis chart of the target substance shown in FIG. 1 and JCPDS data, it was confirmed that it was a single compound of calcium sulfide. Also, as is clear from the scanning electron micrograph shown in FIG. 2, calcium sulfide had a particle size of 6 to 8 μm, and the particle size distribution was relatively uniform.

Example 2 4.516 g of yttrium oxide, 3.781 g of anhydrous sodium sulfite and 6.40 g of sulfur powder were thoroughly mixed in a mortar and then placed in an alumina crucible with a lid and heated at 600 ° C. in an electric furnace at 600 ° C. After heating for an hour, it was cooled to room temperature. Next, the water-soluble sodium sulfate, other trace amounts of thiosulfate, sulfite and sulfide in the obtained reaction product are dissolved and removed with distilled water to completely remove the sodium salt. For this purpose, it was further washed 3 times with cold distilled water. This was dried at 110 ± 10 ° C for 5 hours to obtain the desired product 4.659.
got g. From the X-ray diffraction analysis diagram of the target substance shown in FIG. 3, it was confirmed that the target compound was a single compound of yttrium oxysulfide. Yttrium oxysulfide has a particle size of 6 to 8 μm, as is clear from the scanning electron micrograph shown in FIG.
The particle size distribution was relatively uniform.

Example 3 4.883 g zinc oxide, 18.97 sodium thiosulfate
After thoroughly mixing 3 g and sulfur powder 4.811 g in a mortar, put in an alumina crucible and use an electric furnace to 700
After heating at ℃ for 2 hours, it was cooled to room temperature. Next, the water-soluble sodium salt and the like in the obtained reaction product are dissolved and removed with distilled water, and then the remaining zinc sulfide is removed with distilled water.
Washed twice. Dry this at 110 ± 10 ° C for 2 hours,
5.757 g of the desired product was obtained. From the X-ray diffraction analysis diagram of the target product shown in FIG. 5, it was confirmed to be a single compound of zinc sulfide. Further, zinc sulfide had a particle size of 6 to 8 μm, and the particle size distribution was relatively uniform, as is clear from the scanning electron micrograph shown in FIG.

Example 4 4.516 g of yttrium oxide doped with 4.5% by weight of europium oxide (Eu ₂ O ₃ ), sodium thiosulfate 4.
A reaction mixture was prepared by thoroughly mixing 743 g and 6.40 g of sulfur powder in a mortar. The reaction mixture was placed in a 50 ml alumina crucible and heated in an electric furnace. As a heating method, first, heating at 120 to 150 ° C. for 30 minutes,
Then, a method of heating at 600 ° C. for 2 hours was adopted. At this stage, yttrium and europium oxysulfides are formed, and the temperature was further raised to 1100 ° C. and heating was performed for 2 hours so that europium was doped with yttrium oxysulfide. After turning off the electric furnace and cooling to 800 ° C., the crucible was taken out and rapidly cooled to room temperature.

The reaction product was washed with distilled water three times to remove sodium sulfate and sodium sulfide. The remaining sulfur was washed with a (NH ₄ ) ₂ S _X (x = 2 to 5) solution or CS ₂ and then dried at 110 ± 10 ° C for 5 hours to obtain 4.66 g of Y ₂ O ₂ S: Eu phosphor. Got The emission spectrum of the obtained phosphor is shown in FIG. As a result of comparing the emission intensity of the obtained phosphor with the emission intensity of the phosphor produced under the same conditions using sodium carbonate, a slightly higher efficiency was shown at 100: 97.

Example 5 3.996 g calcium oxide, 7.5 sodium sulfite
A mixture of 62 g and 12.8 g of sulfur was kneaded with an aqueous solution of manganese acetate containing manganese (II) in an amount of 0.2 mol% with respect to calcium oxide. This kneaded product was placed in an alumina crucible having a capacity of 50 ml, and first heated in an electric furnace at 150 ° C. for 1 hour to evaporate water, and then heated to 800 ° C. and further heated for 2 hours. It was further heated at 1000 ° C. so that the crystals of calcium sulfide produced by this reaction were doped with manganese (II). After lowering the temperature of the electric furnace to 800 ° C., the crucible was taken out and rapidly cooled to room temperature, and the water-soluble salt was dissolved and removed with cold distilled water at about 5 ° C., and washed thoroughly. 110 this
After drying at ± 10 ° C. for 5 hours, 2.794 g of a calcium sulfide-based phosphor was obtained. The emission spectrum of the obtained phosphor is shown in FIG. As a result of comparing the emission intensity of the obtained phosphor with the emission intensity of the phosphor produced under the same conditions using sodium carbonate, a considerably high efficiency was shown at 100: 84.

[Brief description of drawings]

FIG. 1 is an X-ray diffraction diagram of CaS obtained in Example 1.

2 is a scanning electron micrograph of CaS obtained in Example 1. FIG.

FIG. 3 is an X-ray diffraction diagram of Y ₂ O ₂ S obtained in Example 2.

FIG. 4 is a scanning electron micrograph of Y ₂ O ₂ S obtained in Example 2.

5 is an X-ray diffraction diagram of ZnS obtained in Example 3. FIG.

6 is a scanning electron micrograph of ZnS obtained in Example 3. FIG.

FIG. 7 is a fluorescence spectrum of Y ₂ O ₂ S: Eu obtained in Example 4.

8 is a fluorescence spectrum of CaS: Mn obtained in Example 5. FIG.

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[Procedure amendment]

[Submission date] July 15, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is an X-ray diffraction diagram of CaS obtained in Example 1.

2 is a scanning electron micrograph showing the particle structure of CaS obtained in Example 1. FIG.

FIG. 3 is an X-ray diffraction diagram of Y ₂ O ₂ S obtained in Example 2.

FIG. 4 is a scanning electron micrograph showing the particle structure of Y ₂ O ₂ S obtained in Example 2.

5 is an X-ray diffraction diagram of ZnS obtained in Example 3. FIG.

6 is a scanning electron micrograph showing the particle structure of ZnS obtained in Example 3. FIG.

FIG. 7 is a fluorescence spectrum of Y ₂ O ₂ S: Eu obtained in Example 4.

8 is a fluorescence spectrum of CaS: Mn obtained in Example 5. FIG.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor 卞 Jong Hong No. 19 Shincheon-dong, Songpa-gu, Seoul, Republic of Korea No. 1207, Rose Apartment 19 (72) Inventor Zhang Su, England 647, Jeongneung-dong, Seongbuk-gu, Seoul, Republic of Korea No. 4 Sanmak Villa No. 206 (72) Inventor's car Zhong Yei, No. 328, Shintyeong 6-dong, Yangcheon-gu, Seoul, Republic of Korea 1330, Mok-dong New Town Apartment No. 104 (72) Inventor Choi ▲ Han ▼ Special in Seoul, South Korea No.3, No.3, 780, Incheon-dong, Seocho-gu, Seocho-gu (72) Inventor ▲ Yu-Yu, 39, No. 1, Shimogetsu-dani, Seongbuk-gu, Seoul, Republic of Korea

Claims (6)

[Claims] 1. A mixture of 1 to 5 mol of sulfite or thiosulfate, 1 to 20 mol of sulfur powder and 1 mol of a metal compound,
A method for producing a high-purity metal sulfide for a phosphor base material, which comprises heating the ground mixture at 300 to 800 ° C. for 2 to 6 hours. 2. The at least one sulfite or thiosulfate selected from the group consisting of sodium sulfite, sodium thiosulfate, potassium sulfite and potassium thiosulfate.
The method according to claim 1, which is a seed. 3. The metal compound is selected from the group consisting of two metals, a first transition metal, an alkaline earth metal, and an alkaline earth metal capable of forming a solid solution sulfide, and a rare earth metal. The production method according to claim 1, which is a sulfate, a halide or an oxide. 4. The metal sulfide is ZnS, CaS, Y.
The production method according to claim 1, which is ₂ O ₂ S or Gd ₂ O ₂ S. 5. The method according to claim 1, wherein the mixture is heated at 600 ° C. for 2 to 4 hours. 6. The metal compound and the sulfite or thiosulfate are preheated and dried at 100 to 200 ° C., and then the sulfur powder is mixed, and then the reaction temperature is raised to be sulfided.
The manufacturing method described.