JPS5913625A - Manufacture of oxysulfide of rare earth element - Google Patents

Abstract

PURPOSE:To manufacture easily the oxysulfide of a rare earth element of high quality, by reacting rare earth element ion with sulfate ion and urea and heating the resulting oxysulfate of the rare earth element in a hydrogen atmosphere. CONSTITUTION:>=1 Kind of rare earth element ion is reacted with sulfate ion and urea in an aqueous soln., and the resulting precipitate or the oxysulfate of the rare earth element obtd. by roasting the precipitate is heated in an atmosphere of gaseous hydrogen or a gaseous mixture of gaseous hydrogen with an inert gas to obtain the oxysulfide of the rare earth element. The rare earth element ion is prepared by dissolving an inorg. or org. acid salt of the rare earth element such as the sulfate, hydrochloride, formate or acetate in an aqueous soln. The sulfate ion is prepared by dissolving sulfuric acid, the sulfate of the rare earth element, the quat. ammonium salt of sulfuric acid such as ammonium sulfate or other salt of sulfuric acid such as pyridinium sulfate in an aqueous soln. A phosphor contg. the oxysulfide of the rare earth element as the base is obtd. by adding an activator for a phosphor to said aqueous soln.

Description

[Detailed Description of the Invention] The present invention relates to a new manufacturing technology for rare earth element oxysulfides, which is easier to operate than conventional manufacturing methods, and has less variation in the quality of the resulting products. It has the characteristic of less sticking. Furthermore, the rare earth element oxysulfide obtained by the production method of the present invention is excellent as a matrix for a phosphor.

Rare earth element oxysulfide has the general formula Ln,0
28 (Ln: rare earth element), and is currently widely used as a fluorescent substance for fluorescent lamps for cathode ray tube illumination for color televisions. As a method for producing this compound on an industrial scale,
Conventionally, a method has been used in which rare earth element oxides are heated and reacted with sulfur in the presence of a brax agent such as soda carbonate or potassium phosphate. This reaction is a reaction between solids at high temperatures, and has the drawback of requiring a long time to increase the reaction rate. Furthermore, when the reaction product obtained by this method is used as a normal inorganic powder material such as a quenching material, pickling and water washing are performed to remove the fluxing agent adhering to the product. It had to be carried out thoroughly and a subsequent drying step was also required.

By roasting the precipitate obtained by first reacting rare earth element ions, sulfate ions, and urea, the present inventors have achieved extremely high uniformity in terms of purity and powder particle size distribution. It was discovered that it was possible to produce rare earth element oxytool fae-1, and applied for a patent.However, by using the precipitate obtained here or the oxysulphate obtained by roasting the precipitate as a raw material, The inventors have discovered a method for producing rare earth element oxysulfide that is much easier than conventional methods and has greater uniformity in terms of purity and particle size distribution, leading to the present invention.

That is, the present invention provides a precipitate obtained by reacting one or more rare earth element ions, sulfate ions, and urea in an aqueous solution, or a rare earth element oxysilane obtained by roasting the precipitate. This is a method for producing oxysulfide of seasonal earth elements, which is characterized in that phenate is heated and reduced in an atmosphere of hydrogen gas or a mixed gas of hydrogen gas and an inert gas.

The rare earth elements in the present invention are elements of the lanthanide group, namely lanthanum, cerium, praseodymium, neodymium, glomethium, samarium, europium, cadrinium, terbium, dysprosicum, holmium, erbium, thulium, ytterbium, and lutetium.
It is a general term for 17 elements including scandium and yttrium. Rare earth element ions are water-soluble salts of one or more elements selected from these, such as sulfates, chlorides, nitrates, formates, acetates, etc.
It may be obtained by dissolving a mechanical salt or an organic salt in water, or it may be obtained by dissolving an oxide, hydroxide, etc. in an acid such as sulfuric acid or hydrochloric acid. That is, the raw material may contain anions other than sulfate ions, such as chloride ions and nitrate ions.

The sulfate ion mixed as a raw material in the present invention can be obtained by dissolving sulfuric acid, a sulfate of a rare earth element, a quaternary ammonium salt of sulfuric acid such as ammonium sulfate, and a salt such as pyridinium sulfate in water.

In carrying out the present invention, the concentration of rare earth element ions in the mixed aqueous solution serving as the raw material is not limited to %. The chemical reaction used in the present invention is a reaction in an aqueous solution, and the product exits the reaction system as a solid. Even if it is filled and remains as a precipitate, as the reaction progresses, the solution will be released and used in the reaction.

In addition, the amount of sulfate ions in the mixed aqueous solution that is the raw material is 1/1/1 mole of rare earth element ions, considering the structure of oxysulfide, which is the target product.
It is clear that 2 moles or more is required. If the sulfate ion is 1/2 or more in molar ratio to the rare earth element ion,
The products obtained are all the same.

Further, the amount of urea varies depending on the quality of the raw material for rare earth element ions and the raw material for sulfate ions. In particular, when there is free sulfuric acid or when sulfuric acid itself is used as a raw material for sulfate ions, the amount of urea required increases. That is, the precipitate, which is an intermediate of the product of the present invention, is decomposed by acid, and is decomposed by free sulfuric acid. This is because it is necessary to neutralize the acid with ions. Naturally, if the amount of urea used is too small, the yield will be low, and the preferable amount is equal to or greater than the number of moles of rare earth element ions. Even if the amount of urea is present in excess of the amount necessary for chemical reactions, the quality of the product will not change.In fact, considering the decomposition of the raw material urea during storage and the increase in reaction rate, the amount of rare earth element ions 8
It is practical to use twice the molar amount.

In order to proceed with the decomposition reaction of urea, water dissolution of the raw material7
Urease, which is a urea degrading enzyme, is added to the aqueous solution by heating it to 0° C. or higher or at around room temperature to cause a reaction. When carrying out thermal decomposition, the preferable reaction temperature is in the range of 90 to 100°C. If the temperature is lower than this,
The decomposition rate of urea is slow and requires a very long reaction time. Further, when all of the urease is used, there is no particular limitation on the amount of urease, but when the amount of urease 11 added is large, the reaction proceeds quickly. In that case, the pH of the water bath solution is preferably 6.4 to 7.6, which is the optimum pH range for urease. Since the enzyme activity decreases at a pH outside this range, the pH is adjusted to the optimum range using an appropriate pH adjuster.

The reaction time varies depending on the reaction temperature, the amount of urea added, the amount of urease added, the type of rare earth element, etc., but as a guide, the reaction is completed in 1 to 5 hours after the reaction solution becomes cloudy. The composition of the precipitate changes as the reaction time progresses;
Although its structure is still unknown, the product obtained by heating and roasting this precipitate in an atmosphere of hydrogen gas or a mixed gas of hydrogen gas and inert gas, regardless of the composition of the precipitate at this time, is It is a rare earth element oxysulfide.

The above sediment'! f) The precipitate is heated once in the air without heating directly in a hydrogen gas atmosphere to convert the precipitate into oxysulfate using the method previously applied for a patent, and then mixed with hydrogen gas or an inert mixture with hydrogen gas. Even if the oxysulfate is heated in a mixed gas atmosphere, the rare earth element oxysulfide that is the object of the present invention can be obtained.

In carrying out the present invention, the temperature at which the precipitate or oxysulfate is heated and reduced in an atmosphere of hydrogen gas or a mixed gas of hydrogen gas and an inert gas is 500 to 1
A suitable range is 000°C, more preferably 550-7
It is in the range of 00°C.

Further, the heating time varies depending on the heating temperature, etc., but in the above heating temperature range, 0.5 to 2 hours is appropriate. Further, hydrogen gas may be used by mixing with an inert gas, specifically, nitrogen gas, argon gas, helium gas, etc. in any proportion.

A practical value for the mixing ratio of hydrogen gas and inert gas is determined by the structure of the heating furnace, the amount of the material to be reduced installed in the heating furnace, the shape of the container, etc. When using a heating furnace that has a structure that makes it difficult for gas to diffuse around the material to be reduced, keep the hydrogen gas mixture ratio low and increase the flow rate to maintain the required amount of hydrogen supply and diffuse the gas around the material to be reduced. Removal of cracked gases in the reactor will increase the rate of reduction.

On the other hand, if the hydrogen gas mixing ratio is made too small, the reducing power will be too weak and the oxidation rate will conversely become slow.

Practical hydrogen gas mixing ratio is 10 as hydrogen gas capacity
It ranges from 0 to 5%, preferably from 7° to 20°.

Unexploded E! A [In the mixed aqueous solution of rare earth element ions, sulfate ions, and urea, as raw materials, elements added to the matrix as activating materials during normal phosphor production, namely europium, terbium, bismuth, By adding a 73-soluble salt such as cerium, for example, chloride, nitrate, sulfate, etc., it is possible to produce a phosphor based on oxysulfide of a rare earth element.

The concentration of the activating material is such that the number of moles of ions of the activating element is 0.1 to 10 (the number of moles of ions of the rare earth element constituting the matrix).
% is appropriate, and the optimum amount varies depending on the combination of elements.

The phosphor obtained in this way is a conventionally known phosphor based on rare earth element oxysulfide, that is, rare earth element oxide and sulfur are combined with sodium carbonate, potassium phosphate, etc. Compared to the powder obtained by heating reaction in the coexistence of a fluxing agent, the present invention shows the same or better performance in terms of brightness. The phosphor obtained by this method has a relative brightness that is comparable to that of the phosphor obtained by the conventional method.

The particle size and particle size distribution of the rare earth element oxysulfide obtained by the method of the present invention can be controlled by fully adjusting the particle size and particle size distribution of the precipitate, which is a precursor, whereas in the conventional method. The particle size of oxosulfide varies depending on the particle size of the rare earth element oxide, which is the front material, and also due to agglomeration under high temperature flux reaction, so it may be difficult to control the particle size [7] It is difficult to obtain all the powder with narrow distribution.

Examples of the present invention are described below.

Examples 1 to 10 The raw materials having the compositions shown in Examples 1 to 10 in Table 1 were each dissolved in 1 t of water and reacted at 95°C for 6 hours with stirring, and the resulting precipitate was collected at 100°C. Hot air drying with temperature adjusted to 0 to 4
It was left to dry for a while. The obtained powder was placed in an alumina crucible, placed in a normal tubular electric furnace, and a mixed gas of 3 volumes of hydrogen gas and 70 volumes of nitrogen gas was added to one side of the furnace tube in 1 minute. The mixture was continuously supplied in an amount equal to the inner volume of the furnace and the tube B, and the crucible was heated to 114° C. so that the internal temperature of the crucible reached 650° C., and was heated for 1 hour.

After 6 hours, X-ray diffraction analysis of each reaction product revealed that
The diffraction peaks shown in Tables 2(A) to (Jl) were shown, respectively, and were in good agreement with the values of oxysulfide of each rare earth element listed in the ASTM card.

Furthermore, when the molar ratio of rare earth elements to sulfur (Ln/S) in the powders obtained in Examples 1 to 1o was measured by fluorescent X-ray, the values shown in Table 1 were obtained. These values are in close agreement with the theoretical values for pure oxysulfide. Based on the above results, Examples 1 to 1o
In both cases, the powder obtained proves to be pure oxysulfide.

Comparative Example 1 Yttrium oxide Y, 0310y Sulfur S
49 Sodium Carbonate Na2CO36f Potassium Phosphate +7 3PO4・3H201V Put the above substances into a polyethylene bottle and mix thoroughly.

This was placed in an alumina crucible and heated to 1150' in air.
Roasted at C for 3 hours. After firing, the powder is crushed and
Conventional post-treatments such as classification, pickling, water washing, and drying were performed.

The product thus obtained was similar to that of Example 1.
Although the line diffraction pattern shows a slight yellowish tinge, the molar ratio of Y and S (Y/s) was added to d using fluorescent Xi and was 1.95, and the flame atomic absorption When the sodium content was measured by the method, it was found that 0.2% of Na remained in the product.

Fig. 1 shows the particle size and distribution of the .f sotrium oxysulfide powder obtained in Example 1 and Example 1. As can be seen from FIG. 1, the oxynalphide obtained by the present invention has a smaller particle size and a wider distribution than that obtained by the conventional method.

Comparative example 2 Acclimatized lanthanum La2O310f Rest Yellow S
2f charcoal 11 cheap boot lium Na, C
o,, 6f! Phosphorus 1ga Potassium K, PO, ・3H101f Above y4.1. −
Pour into a polyethylene bottle and shake to mix thoroughly. This material was placed in an all-alumina crucible and heated for 1100' in air.
Roasted at C for 3 hours. After roasting, the powder is crushed and
Conventional post-treatments such as classification, pickling, water washing, and drying were performed.

As a result of X-ray diffraction of the powder obtained in (2), the diffraction pattern showed that in addition to the peak of lanthanum oxysulfide, there was also a peak other than the compound (peak of La20.). As can be seen, in the raw material composition in this comparative example, lanthanum oxide was also mixed together with lanthanum oxysulfide.

-Furthermore, FIG. 2 shows the particle size distribution of the lanthanum oxysulfide powder obtained in Example 6 and Comparative Example 2, respectively. As can be seen from FIG. 2, the lanthanum oxysulfide obtained by the present invention had a smaller particle size and a sharper distribution than that obtained by the conventional method.

Examples 11 to 14 Each of the raw materials having the compositions listed in Examples 11 to 14 in Table 3 was
The precipitate produced as a result of reaction in water at 95'C for 3 hours with stirring was heated to 800 °C after drying.
It was incubated at ℃ for 2 hours. The powder obtained by the above procedure was found to be oxysulfate of each of yttrium, gadolinium, lanthanum, and samarium by X-ray diffraction and by dissolving the powder in hydrochloric acid and measuring the molar ratio of rare earth elements and sulfur in the solution. It was confirmed that there is. Therefore, each powder obtained was placed in an alumina crucible, placed in a regular tubular electric furnace, and a mixed gas of 30 volumes of hydrogen gas and 70 volumes of nitrogen gas was applied from one side of the furnace tube for 1 minute. The crucible was continuously supplied at a rate of 1/6 of the internal volume of the furnace tube, and the temperature inside the crucible was adjusted to 650° C., and roasted for 2 hours.

After cooling, each reaction product was subjected to X-ray diffraction, and the results showed the diffraction peaks shown in Tables 4 (A) to (D), respectively.
Good agreement was observed with the values for oxysulfide of each rare earth element listed on the STM card.

Furthermore, regarding the powders obtained in Examples 11 to 14, the molar ratio of rare earth elements to sulfur (Ln /
S) 11! I determined that each was 2.05.

2.05, JOB, 2.08. The above results prove that the powders obtained in all of Examples 11 to 14 are pure oxysulfides.

≠ 1 Table 3 Table 2 (J) Table 4 (D) Table 2 (■) Table 4 (B) Example 15 Yttrium sulfate Y! (SO4)3・8H, O45,
75F urea
60 2 11 t of mixed aqueous solution of the above substances were washed, the precipitate formed as a result of reaction at 95°C for 6 hours was filtered, and the powder obtained after drying was placed in an alumina crucible and placed in an ordinary tubular electric Installed in the furnace, a mixed gas of 50 volumes of hydrogen gas and 50 volumes of nitrogen gas was introduced from one side of the furnace core tube.
'R' continuously at a supply rate of 1/3 of the inner volume of the reactor core tube per minute.
The temperature inside the crucible was adjusted to 600℃.
Roast for 2 hours [7 hours].

After cooling, the reaction product was subjected to X-ray diffraction, and as a result, a diffraction pattern similar to that of yttrium oxysulfide obtained in Example 1 was obtained. In addition, Keikou X
The molar ratio of Y and S (Y/S) was measured using a line and found to be 2.06. The above results demonstrate that the obtained powder is pure yttrium oxysulfide. Note that the yield was 96 times.

Example 16 Yttrium sulfate Y2(804)3.8H, O45,
75r urea
60 1 1 ton of mixed aqueous solution of the above substances was added to Keyaki,
Filter the precipitate formed as a result of reacting at 95°C for 3 hours,
After drying, the obtained powder was placed in an alumina crucible, placed in a normal tubular electric furnace, and a mixed gas of 50 volumes of hydrogen gas and 50 volumes of nitrogen gas was supplied from one side of the furnace tube to the core every minute. Flow continuously at a supply rate of 1/6 of the internal volume of the tube,
The temperature inside the crucible was adjusted to 900°C and roasted for 2 hours.

After cooling, the reaction product was subjected to X-ray diffraction, and the results are shown in Table 5.
However, as can be seen from this table, the diffraction pattern included a peak of yttrium oxide as well as a peak of yttrium oxysulfide. That is, in this experiment, some yttrium oxysulfide was produced, but yttrium oxide was also mixed.

Example Yttrium sulfate yt(so4)s・8H2045,
759 Urea
60 7 Mixed aqueous solution of the above substances/(Mt Hayashi, accounted for,
The precipitate formed as a result of reaction at 95°C for 6 hours was filtered,
After drying, put the obtained powder into an alumina IJt receptacle,
Installed in an ordinary tubular electric furnace, a mixed gas of 5 volumes of hydrogen gas and 95 volumes of nitrogen gas is supplied from one side of the furnace core tube at a rate of one-third of the inner volume of the furnace core tube per minute. The mixture was poured continuously, the temperature inside the roots pot was adjusted to 600°C, and roasted for 2 hours.

After cooling, the reaction product was subjected to X-ray diffraction, and the results are shown in Table 6.
However, as can be seen from this table, the diffraction pattern included a peak of yttrium oxysulfide as well as a peak believed to be ocyanide of yttrium. That is, in this experiment, some yttrium oxysulfide was produced, but yttrium oxide was also mixed.

Table 5 Table 6 Example 18 Sulfuric acid 1) Ram Yz(SO4)3・8 ■I, 04
5.759 urine cumulative
1 t of mixed aqueous solution of 20 g of the above substances to 4+il
After reacting at 95°C for 3 hours under constant stirring, the resulting powder was filtered through Kanazawa and dried. A mixed gas of 50 volumes of hydrogen gas and 50 volumes of nitrogen gas is continuously flowed from one side at a supply rate of 1/6 of the internal volume of the furnace tube per minute, and the temperature inside the crucible reaches 650℃. The temperature was adjusted accordingly and roasted for 2 hours.

After cooling, the reaction product was subjected to X-ray diffraction, and as a result, a diffraction pattern similar to that of yttrium oxysulfide obtained in Example 1 was obtained. Furthermore, when the molar ratio of Y and S (Y, /S) was measured using fluorescent X-rays, it was found that 2
．． 02, and the above results prove that the obtained powder is pure yttrium oxysulfide. The yield was 65% and 7v.

Example 19 Yttrium sulfate Yt(SO4)3.8H, O45,
75r urea
60 7 1 t of mixed aqueous solution of the above substances was stirred, 9
Filter the precipitate # generated as a result of reacting at 5°C for 30 minutes,
After drying, the obtained powder was placed in an alumina crucible, placed in a normal tubular electric furnace, and a mixed gas of 60 volumes of hydrogen gas and 50 volumes of nitrogen gas was added to one side of the furnace tube.
The crucible was continuously flowed at a feed rate of one-fifth of the inner volume of the furnace tube per minute, and the temperature inside the crucible was adjusted to 650° C., and roasted for 2 hours.

After cooling, the reaction product was subjected to X-ray diffraction, and as a result, a diffraction pattern similar to that of the yttrium oxysulfide obtained in Example 1 was obtained. Furthermore, when the molar ratio of Y and S (Y/S) was measured using fluorescent X-rays, it was found that 2.
05, and the above results prove that the obtained powder is pure yttrium oxysulfide. Note that the yield was 68%.

Example 20 Yttrium sulfate Yt (804)3.8H2045
,75r urea
60 2 While stirring 1 t of mixed aqueous solution of the above substances,
The precipitate produced as a result of reaction at 95°C for 6 hours was filtered,
After drying, the obtained powder was placed in an alumina crucible, placed in an ordinary tubular electric furnace, and hydrogen was injected into it from one side of the furnace tube.
A mixed gas of 50 volumes of gas and 50 volumes of nitrogen gas is continuously supplied at a rate of 1/6 of the internal volume of the furnace tube per minute.
Then, the temperature inside the crucible was adjusted to 650° C., and calcined for 6 hours.

After cooling, the reaction product was subjected to X-ray diffraction, and as a result, a diffraction pattern similar to that of the yttrium oxysulfide obtained in Example 1 was obtained.

Furthermore, when the molar ratio of Y and S (Y/S) was measured using fluorescent X-rays, it was 2.00, and based on the above results,
The powder obtained is proven to be pure yttrium oxysulfide. In addition, from 7 yield V, 5
%Met.

Example 21 Yttrium sulfate Yz (SOJs・8H, O45,75
rEuropium sulfate Eu, (804)3.8H,01
,66V urea
The precipitate produced as a result of reacting 1 t of mixed aqueous solution of the above substances at 95°C for 5 hours with stirring was filtered, dried, and placed in the resulting powdered gold-alumina crucible, and placed in a conventional tubular electric furnace. A mixed gas of 30 volumes of hydrogen gas and 70 volumes of nitrogen gas is captured from one side of the reactor core tube.
The crucible was continuously fed at a rate of one-third of the internal volume of the furnace tube per minute, heated to a crucible internal temperature of 650°C, and roasted for 2 hours.

After cooling, the reaction product was subjected to X-ray diffraction, and as a result, a diffraction pattern similar to that of the yttrium oxysulfide obtained in Example 1 was obtained.

Furthermore, when the molar ratio of Y and S (Y/S) was measured using fluorescent X-rays, it was 2.05, and the ratio of europium to yttrium, which was measured at the same time, was 6.02 molar. Based on the above results, is the europium activation amount 1 yttrium oxysulfide? to Xj l-, 0,
KJR stylish Y2O2S which is 0369f/; proves that Eu was obtained.

Comparative Example 3 Yttrium oxide Y, 0310 @ europium oxide raw +20. 0.8Fish 1 [Yellow S
4 ≦-1st generation Na2Co,
6! ;') /$-h! To J Ram, PO
4.3H, O' I V's direct product d' k Pour into a polyethylene bottle and shake 7. Mix and sweeten thoroughly. Put this in a gold alumina nozzle, and
[((' lil Q roasted. R, 1
After that, it was subjected to the usual post-treatments such as crushing, classification, pickling, water washing, and drying.

When X-ray diffraction was performed on the powder thus mixed, it was found that 1TFC was in good agreement with the yttrium oxysulfide V which is included in the ASTM card. Instead of profit i white, ya −τ・y(
Color fL color is 1ζ. When the cell ratio of Y and S (Y/S) was measured using Kuiko X-con, it was 1.96! r
When the sodium content was measured by the Flame Prince method, 0.1% of Na remained in the product.

Retaeuropium-activated yttriutoxysulfide Y2O obtained in Example 21 and Comparative Example 3, respectively
When the particle size distribution of the 25iEu powder was determined, it was found that the yttrium oxysulfide obtained by the present invention had a smaller particle size and sharper distribution than that obtained by the conventional method. The average particle size is 6 each
．． They were 8μ and 5.5μ.

Next, these powders were packed into a sample cell and molded, and then set in a Shimadzu fluorescence photometer RF-500, and detected with a photomultiplier tube to detect the emission in the 90° direction (wavelength) at an excitation wavelength of 527 nm. 626 nm) When all measurements were carried out, the Joy Si obtained in Example 21VC
For Eu, the relative strength was 64, while for Y, 02 Si Eu obtained in Comparative Example 3, the relative strength was 58. That is, the phosphor based on yttrium oxysulfide obtained in the present invention has a luminescence intensity 1i degree improved by about 10% compared to the phosphor based on oxysulfide obtained by the conventional method.

Example 22 Gadolinium sulfate Gd2(SO4), 8H7026
,14! i' Terbium sulfate Tbt (504)s・
811,0 0,74 rurea
60 liters of mixed aqueous solution of the above substances was poured into a tube and allowed to react at 100°C for 6 hours. After drying, the resulting powder was placed in an alumina crucible and heated in a regular tubular electric kettle. Installed in the furnace, and from one side of the furnace tube, 70 volumes of hydrogen gas and 30 volumes of nitrogen gas were added.
A volumetric mixed gas was continuously supplied at a rate of one-third of the inner volume of the furnace tube per minute, and the temperature inside the crucible was adjusted to 650° C., and roasted for 2 hours.

After cooling, the reaction product was subjected to X-ray diffraction, and as a result, a diffraction pattern similar to that of the gadolinium oxysulfide obtained in Example 9 was obtained.

Furthermore, the molar ratio of Gd and S (Gd/S
) When ffi was measured, 2. [16, and at the same time d11] The ratio of terbium to gadolinium was determined to be 2.98 mol. Based on the above results, pure Gd, 02S;
It is proven that b is obtained.

Comparative Example 4 Gadolinium oxide cd, o, 10 f/
Terbium oxide Tb40. 0.4 f sulfur
Yellow S 37 Sodium carbonate Na2CO,, 6f/Potassium phosphate and 3PO, -3H, 01Y Place the above substances in a polyethylene bottle and shake to mix thoroughly. This was placed in an alumina crucible and roasted at 115°C in air for 3 hours.The roasted powder was subjected to the usual post-processing steps such as crushing, classification, pickling, water washing, and drying.

When the powder thus obtained was subjected to X-ray diffraction, good agreement was found with the value for gadolinium oxysulfide listed in the ASTM card.
The color of the powder was not pure white, but rather yellowish. The molar ratio of Cd and S (Gd/s) was measured using optical X-rays at measurement port Q and was 1.97, and sodium gold was measured using a flame atomic absorption chisel. .1% Na remained.

Actual MCh Example 22 and Comparative Example 4 When the particle size distribution of the powder of terbium-activated gadolinium oxysulfide (Gd 202 S i Tl) obtained in VC was measured, it was found that The particle size of Fido was smaller and its distribution was sharper than that obtained by the conventional method.

The average particle size L[, 6.5μ and 5.2μ, respectively.

Next, these powders were crystallized and molded into a sample cell, and then set in a fluorescent photolithography RF-500 manufactured by Shimadzu, and detected by a photomultiplier tube in the 90° direction at an excitation wavelength of 543 nm. When light emission (wavelength 3750 m) was measured, Gd, O, S obtained in Example 22; Tb
The relative strength was 70, while the relative strength was 62 for Gd, 0.5iTb obtained in Comparative Example 4. That is, the phosphor based on gadolinium oxysulfide obtained in the present invention has improved luminance by about 13 degrees compared to the phosphor based on oxysulfide obtained by the conventional method.

Example 23 Lanthanum sulfate La= (so4)3・qHto
10,19y europium chloride EuCIAo, 21
? Urea
50 7 While stirring 1 t of mixed aqueous solution of the above substances, 10
The precipitate produced as a result of the reaction at 0°C for 2 hours was filtered out, and after drying, the obtained powder was placed in an alumina crucible, placed in a normal tubular electric furnace, and hydrogen gas was injected from one side of the furnace tube. 6
A mixed gas of 0 volume and 70 volumes of bed gas was continuously supplied at a rate of 1/3 of the internal volume of the furnace tube per minute, and the temperature inside the crucible was adjusted to 700 °C. Roasted for an hour.

After cooling, the reaction product was subjected to X-ray diffraction, and as a result, a diffraction pattern similar to that of the lanthanum oxysulfide obtained in Example B was obtained. Furthermore, when the molar ratio of υLa and S (La/S) was measured using fluorescent X-rays, it was found that 2
．． 05, and the ratio of europium to lanthanum measured at the same time was 3.04 molti. Based on the above results, pure La, 02S with europium activation amount of 0.0270y for lanthanum oxysulfide 12
; It is clear that Eu was obtained.

Comparative Example 5 Lanthanum oxide La20. , 10? Europium oxide Eu, 0. 0.47 sulfur
3 5L? Sodium carbonate Na, CO,, 69 Potassium phosphate K, PO4・3) (, Q I
YPour the above substances into a polyethylene bottle and shake to mix thoroughly. This was placed in an alumina crucible Z and roasted in air at 1150°C for 6 hours. After roasting, the powder was subjected to post-processing to make it conductive, such as crushing, classification, chemical processing, washing with water, and drying.

When the powder thus obtained was subjected to X-ray diffraction, good agreement was found with the value for lanthanum oxysulfide listed in the ASTM card, but the color of the powder was not pure white but slightly yellow. It had a taste. When the molar ratio of La and S (La/S) was measured using fluorescent X-rays, it was 1.97, and when sodium was measured using flame atomic absorption spectrometry, it was found that 0.0.
0.8% Na remained.

Europium-activated lanthanum oxysulfide La201 obtained in Example 23 and Comparative Example 5, respectively
When the particle size distribution of SiEu powder was measured, it was found that the lanthanum oxysulfide obtained by the present invention had a smaller particle size and sharper particle size distribution than that obtained by the conventional method.

The average particle diameters were 4.2μ and 5.0μ, respectively.

Next, these powders were packed into a sample cell and molded, and then transferred to a Shimadzu fluorescence photometer RF-500 and detected by a photomultiplier tube to detect the emission in the 90° direction at an excitation wavelength of 527 nln. (Wavelength 626 nm) When f was measured, La obtained in Example 25, 02S i
Eu had a relative strength of 55, while La2O2S i Eu obtained in Comparative Example 5 had a relative strength of 50. That is, the phosphor based on gadolinium oxysulfide obtained in the present invention has a luminance of 10 times higher than the phosphor based on oxysulfide obtained by the conventional method.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the particle size distribution of the powders obtained in Example 1 and Comparative Example 1, and FIG. 2 is a graph showing the particle size distribution of the powders obtained in Example 6 and Comparative Example 2. Okay: +: (, a) 1,200,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 Column Diameter (Kai)

Claims (4)

[Claims] (1) A precipitate obtained by reacting one or more rare earth element ions, sulfate ions, and urea in an aqueous solution, or a rare earth element oxysulfate obtained by roasting the precipitate, is hydrogenated. A method for producing rare earth element oxysulfide, which is characterized by heating in a gas atmosphere or a mixed gas atmosphere of hydrogen gas and inert gas. (2) The rare earth element ion is a sulfate, chloride, or
The method for producing oxysulfide according to claim 1, wherein the oxysulfide is produced by dissolving an inorganic or organic acid salt such as formate or acetate in an aqueous solution. (3) The sulfate ion is obtained by dissolving sulfuric acid, a sulfate of a rare earth element, a quaternary ammonium salt of sulfuric acid such as ammonium sulfate, or a salt such as pyridinium sulfate in an aqueous solution. Method for producing oxysulfide. (4) The method for producing oxysulfide according to claim 1, wherein the aqueous solution contains an activating material for a fluorescent material.