JP2001288460A - Production method for rare earth phosphor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method whereby a high-purity phosphor which does not contain iron, copper, and chromium elements can be regenerated or produced from a rare earth phosphor containing iron, copper, and chromium elements as impurities or from a rare earth oxide which is the raw material of the phosphor. SOLUTION: This method for producing a rare earth phosphor includes, in the following order, (a) the step of dissolving a rare earth phosphor or a rare earth oxide as the raw material of the phosphor in a mineral acid; (b) the step of forming the precipitate of iron, copper, and chromium dissolved in the above-prepared solution and causing an adsorbent to adsorb the precipitate to remove it; (c) the step of adding oxalic acid and/or dimethyl oxalate to the solution to form a rare earth oxalate; and (d) the step of thermally treating the oxalate to give a rare earth oxide.

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 rare earth phosphor such as an oxysulfide rare earth phosphor.

[0002]

As a red-emitting phosphor of a color picture tube, europium-activated sulfide yttrium phosphor is a rare earth phosphor _{(Y 2 O 2 S: Eu} ) , but is often used, these are raw materials of rare earth elements And expensive
Collecting and reusing this is important from the viewpoint of not only effective use of resources but also reduction of manufacturing costs.

For this reason, various recovery and regeneration techniques have been developed for rare earth phosphors.

[0004] However, most of these methods physically recover and regenerate the phosphor from excess phosphor slurry containing a high concentration of the phosphor generated in the process of developing the phosphor film of the color cathode-ray tube. Although it is useful as a method for collecting and regenerating phosphors that are not
It is unsuitable for recovery from sludge having a low phosphor-containing concentration such as scattered phosphor slurry or suspended particles of phosphor particles generated in the process of producing the phosphor.

[0005] With respect to such degraded phosphors, it is necessary to chemically decompose the collected phosphors and regenerate them as a rare earth oxide raw material. For example, oxysulfide rare earth phosphors are converted to hydrochloric acid, nitric acid, A method has been proposed in which a rare earth ion solution is dissolved with a mineral acid such as sulfuric acid to form a rare earth ion solution, oxalic acid is used to precipitate a rare earth oxalate, dried, and then decomposed at a high temperature to form a rare earth oxide.

In this method, a rare earth oxide such as yttrium oxide is dissolved in a mineral acid to form a rare earth ion solution, and then oxalic acid is used to precipitate a rare earth oxalate, which is dried and decomposed at a high temperature to remove the rare earth oxide. This is an application of a method for newly producing an oxysulfide rare earth phosphor as a raw material to be manufactured.

[0007]

However, in such a method, if the elements of iron, copper, and chromium are adhered to the phosphor, those ions are also contained in the rare earth ion solution, In the next step, although oxalic acid selectively reacts with the rare earth element, it is included in the precipitate, remains in the rare earth oxide as it is, and only lowers the brightness of the phosphor made from this rare earth oxide. However, when used for forming a fluorescent film of a color cathode ray tube, there is a problem that the other light emitting phosphors are discolored.

Usually, carbon (dug), photosensitive resin such as polyvinyl alcohol or dichromate, pigment such as iron oxide (Fe ₂ O ₃ ), dispersant, etc. adhere to the recovered phosphor. Therefore, the rare earth ion solution in which this is dissolved contains metal ions such as iron, copper, and chromium in addition to the rare earth ions.

Therefore, a method of removing metal ions of iron, copper and chromium, which greatly affect the properties of the phosphor, from the rare earth ion solution and regenerating a sufficiently purified high-purity phosphor. Is required.

[0010] In the case of newly producing a phosphor, a method similar to the above-mentioned regenerating method is generally used. That is, in this method, a rare earth oxide such as yttrium oxide is dissolved in a mineral acid to form a rare earth ion solution, and then oxalic acid is used to precipitate a rare earth oxalate. Things.

Therefore, even when such a phosphor is newly manufactured, if iron or the like is contained in the rare earth oxide as a raw material, they remain on the phosphor without being removed, as described above. It may cause a significant decrease in luminance.

The present invention has been made in view of such conventional circumstances, and is intended to convert a rare earth-based phosphor containing a metal element of iron, copper, or chromium as an impurity or a rare earth oxide as a raw material thereof into iron, copper, or the like. It is an object of the present invention to provide a method capable of regenerating or producing a high-purity phosphor containing no chromium metal element.

[0013]

In order to achieve the above object, a method for producing a rare earth phosphor according to the present invention contains at least one of iron, copper and chromium as an impurity. A method of producing a high-purity rare earth phosphor from a rare earth phosphor or a rare earth oxide as a raw material thereof, wherein (a) a step of dissolving the rare earth phosphor or the rare earth oxide as a raw material thereof with a mineral acid (B) forming a precipitate of iron, copper and chromium which dissolves in said solution;
Removing the precipitate by adsorbing it on an adsorbent, (c)
A step of adding oxalic acid and / or dimethyl oxalate to the solution to generate a rare earth oxalate, and (d) a heat treatment of the generated rare earth oxalate to obtain a rare earth oxide. It is characterized by:

In the present invention, as described in claim 2, the formation of the precipitate of iron, copper and chromium in the step (b) is performed by (i) after adding a hydrogen peroxide solution to the solution. And neutralizing by adding aqueous ammonia, and (ii) introducing a hydrogen sulfide gas after adding nitrate to the solution.

In the present invention, zinc sulfide is exemplified as the adsorbent.

In the present invention, as described in claim 4, after the step (d), a step (e) of adding a flux to the rare earth oxide and firing may be performed.

According to the purification method of the method for producing a rare earth phosphor of the present invention described above,
The mineral acid in the step (a) is preferably hydrochloric acid and / or nitric acid.

Further, as described in claim 6, (c)
In the step, it is preferable that the heat treatment temperature is 700 ° C. to 1100 ° C., and further, as described in claim 7,
In the step (c), it is desirable that the generated rare earth oxalate is washed with water, filtered and dried, and then heat-treated.

In the present invention, a rare earth phosphor or a rare earth oxide as a raw material thereof is dissolved in a mineral acid solution.
If iron, copper or chromium is dissolved, their precipitates are formed and the precipitates are adsorbed and removed by the adsorbent to obtain high purity rare earth oxides without such metals be able to. As a result, from the rare earth phosphor or the rare earth oxide as a raw material containing iron, copper or chromium as an impurity, such an impurity is not contained, and therefore, the luminance characteristics are deteriorated and other phosphors are adversely affected. It is possible to regenerate or produce a high-purity phosphor without any problem.

[0020]

Embodiments of the present invention will be described below.

In the present invention, first, a rare earth phosphor or a rare earth oxide as a raw material thereof is dissolved in a mineral acid (step (a)).

The kind of the rare earth phosphor is represented by the following general formula:
Re ₂ O ₂ S (where Re is Y, La, Ce, Pr, N
d, Pm, Sm, Eu, Gd, Tb, Dy, Ho, E
oxsulfide rare earth phosphors substantially represented by at least two rare earth elements selected from r, Tm, Yb and Lu), but are not particularly limited thereto. Further, the rare earth phosphor may be recovered as a loss in the manufacturing process of the phosphor, or may be recovered as surplus or loss in the process of forming the fluorescent film of the color CRT. Is also good. Further, the phosphor may be a phosphor that has been subjected to a treatment such as removal of impurities from the phosphor, or may be a phosphor that has been recovered as a loss during the treatment process.

Such a phosphor or a rare earth oxide as a raw material thereof is dispersed in pure water such as deionized water, if necessary, filtered to remove foreign substances, and then dissolved in a mineral acid. It is desirable to use at least one of hydrochloric acid and nitric acid as the mineral acid.

In the present invention, particularly when the phosphor is dissolved, the phosphor is first dispersed in hydrochloric acid, and then nitric acid is gradually added to the dispersion, preferably while stirring the dispersion. It is preferable to use a method of dissolving the phosphor. By using such a method, the phosphor can be dissolved in a short time, and when the phosphor is an oxysulfide rare earth phosphor, the oxidizing effect of nitric acid on sulfur generated during dissolution is suppressed. Therefore, precipitation of the rare earth element as a sulfate is reduced, and the yield of the rare earth oxide can be increased. Further, although the dissolution time is short, the dissolution reaction does not proceed violently, so that there is an advantage that it is not necessary to use a large-scale reaction vessel.
It is preferable to use hydrochloric acid having a concentration of 21% by weight to 38% by weight. The amount is usually 50 parts by weight to 150 parts by weight, preferably 80 parts by weight to 100 parts by weight, based on 100 parts by weight of the phosphor (in terms of solid content). Dispersion in hydrochloric acid,
This can be done by stirring, while the liquid temperature
It is preferable to heat and maintain at 50 ° C to 90 ° C. On the other hand, nitric acid usually has a concentration of 62 to 72% by weight,
Min / phosphor 1 kg-2.0 ml / min / phosphor 1 kg, preferably 0.8
With the addition rate of 1 ml / min / 1 kg of phosphor to 1.2 ml / min / 1 kg of phosphor, the total amount is 5 parts per 100 parts by weight of phosphor (in terms of solid content).
0 to 150 parts by weight, preferably 80 to 100 parts by weight, is added. By continuing the stirring for about 0.5 to 3 hours after the addition, the phosphor is dissolved, and a rare earth element ion solution is obtained.

Next, a precipitate of iron, copper and chromium dissolved in the rare earth element ion solution is formed, and the precipitate is adsorbed on an adsorbent and removed (step (b)).

The formation of the precipitates of iron, copper and chromium can be performed, for example, by (i) adding hydrogen peroxide solution to the rare earth element ion solution, adding ammonia water to neutralize the solution, and then (ii) adding the rare earth element solution. After adding lead nitrate to the ionic solution, a step of introducing a hydrogen sulfide gas can be performed.

That is, first, in step (i), by adding aqueous hydrogen peroxide to the rare earth element ion solution, the divalent iron ions (Fe ²⁺ ) dissolved in the rare earth element ion solution are trivalent. Of iron ions (Fe ³⁺ )
Next, the solution is neutralized with aqueous ammonia to make iron hydroxide (Fe
(OH) ₃ ) A precipitate is formed. The amount of the hydrogen peroxide solution varies depending on the amount of iron ions present in the rare earth element ion solution, but is usually 0.005% by weight to 0.1% with respect to the phosphor or the rare earth oxide (solid conversion) of the raw material thereof. % By weight. If the content is less than 0.005% by weight, the valence of iron ions will be insufficiently changed, resulting in insufficient formation of a precipitate to be removed as iron hydroxide. Not much different.

Next, in step (ii), lead nitrate is added to the rare earth element ion solution, and chromium ions dissolved in the rare earth element ion solution are converted into lead chromate (PbCr).
After precipitation as O ₄ ), hydrogen sulfide gas is introduced,
Copper ions dissolved in the rare-earth element ion solution are precipitated as copper sulfide, and lead ions remaining in the solution without contributing to the reaction with chromium ions are precipitated as lead sulfide. The amount of nitrate added varies depending on the amount of chromium ions present in the rare earth element ion solution, but is usually 0.005% by weight to 0.5% by weight based on the rare earth oxide (in terms of solid content) of the phosphor or its raw material. Range. 0.005% by weight
If the amount is less than 0.5%, the formation of the precipitate to be removed as lead chromate becomes insufficient, and even if the amount exceeds 0.5% by weight, the effect does not change much, only an excess. The hydrogen sulfide gas also varies depending on the amount of copper ions and lead ions present in the rare earth element ion solution, but is usually 3 ml / min / min.
At an addition rate of 1 kg to 20 ml / min of phosphor / 1 kg of phosphor, 5 minutes to 2 minutes
Introduce for 0 minutes. If the addition rate is less than 3 ml / min / phosphor 1 kg, the formation of sulfide precipitates becomes insufficient, copper and lead ions cannot be removed, and the addition rate is 20 ml / min / phosphor.
Even if used over 1kg, the effect will not change much, only the excess. Also, if the introduction time is less than 5 minutes,
If the sulfide precipitation is insufficient and the introduction time exceeds 20 minutes, the effect does not change much.

Thereafter, an adsorbent is charged into the rare-earth element ion solution to adsorb the precipitate containing iron, copper and chromium generated in the above steps (i) and (ii). As the adsorbent, zinc sulfide, graphite, ion exchange resin,
Zeolite and the like are exemplified, and among them, use of zinc sulfide is preferred from the viewpoint of specific gravity. The amount of the adsorbent added is usually in the range of 0.5% by weight to 5% by weight based on the phosphor or the rare earth oxide (as solid content) of its raw material.
The adsorbent adsorbing the precipitate containing iron, copper and chromium is then removed from the system using a continuous centrifugal dehydrator or the like.

Next, if necessary, the rare earth element ion solution that has passed through the above step (b) is subjected to a filtration treatment, and then oxalic acid and / or dimethyl oxalate is added thereto and stirred to obtain a rare earth oxalate salt. (Step (d)).

The amount of oxalic acid and / or dimethyl oxalate added in this step (c) is usually from 110 parts by weight to 390 parts by weight based on 100 parts by weight of the phosphor or the rare earth oxide (as solid content) as its raw material. Parts by weight, preferably 120 to 220 parts by weight
Parts by weight. If the added amount is less than 110 parts by weight with respect to 100 parts by weight of the phosphor (in terms of solid content), the rare earth oxalate salt formation reaction does not proceed and the yield of rare earth oxides is reduced. Also, 390
If the amount exceeds part by weight, the excessive addition does not contribute to the rare earth oxalate salt formation reaction. The addition of oxalic acid, etc.
It is desirable to heat the solution at 55 ° C. to 90 ° C. and to stir the solution. By continuing stirring for about 0.5 to 2 hours after the addition, the rare earth element ion reacts with oxalic acid or the like to generate a rare earth oxalate.

Thereafter, the mixture is allowed to stand to sediment the rare earth oxalate, the supernatant is removed, and, if necessary, washed with water, filtered and dried, and then heat-treated (step (d)).

In the water washing, it is preferable that the supernatant is repeatedly washed with pure water such as deionized water or distilled water until the pH of the supernatant becomes 5.0 or more. Dry at about 150 ° C for 12 hours to completely remove water.

The heat treatment is performed using a continuous roasting furnace or the like to separate the separated rare earth oxalate at 700 ° C. to 1100 ° C. for 1 hour to 4 hours, preferably at 800 ° C. to 1000 ° C. for 2 hours to 3 hours. .
As a result, a high-purity rare earth oxide containing no iron, chromium, or copper can be obtained.

The rare earth oxide thus obtained is
By adding a flux and firing (step (e)), a high-purity phosphor can be obtained.

For example, a rare earth oxide phosphor can be obtained by heating and baking at 1150 ° C. to 1500 ° C. for 1 hour to 6 hours in air using barium chloride or magnesium chloride as a flux.

Further, by using an alkali metal carbonate such as sodium carbonate or potassium carbonate, sulfur, potassium phosphate or the like as a flux, calcination is carried out by heating at 800 ° C. to 1250 ° C. for 1 hour to 6 hours in air to obtain oxysulfide. A rare earth phosphor can be obtained.

The obtained phosphor is optionally filtered,
Final purification such as drying and sieving is performed as appropriate, and the product is put to practical use.

As described above, according to the method for producing a rare earth phosphor of the present invention, iron or a rare earth element ion solution obtained by dissolving a rare earth oxide as a raw material of the phosphor in a mineral acid is added to the phosphor.
When chromium and copper ions are contained, they are selectively precipitated, and the precipitates are adsorbed and removed by an adsorbent, so that these impurities are almost completely removed from the rare earth element ion solution. can do. Therefore, a high-purity rare-earth oxide containing almost no impurities of iron, chromium, and copper can be obtained, and a high-purity phosphor can be obtained using such a high-purity rare-earth oxide as a raw material. .

The method for producing a rare-earth phosphor of the present invention is useful for regenerating a degraded rare-earth phosphor which is difficult to regenerate by a so-called physical regeneration method, and a rare-earth oxide containing iron, chromium, and copper. It is also useful as a method for newly producing a rare-earth phosphor using a material as a raw material.

[0041]

EXAMPLES Next, specific examples of the present invention will be described, but the present invention is not limited to these examples. In the following description, all parts are parts by weight, and unless otherwise specified, percentages such as composition and blending ratio represent percentages by weight.

EXAMPLE A europium-activated yttrium oxysulfide phosphor (Y ₂ O ₂ S: Eu) to which a photosensitive resin such as polyvinyl alcohol or dichromate, a pigment, and the like, which were collected from a coating process of a fluorescent screen of a color cathode ray tube, were adhered. ) 100 kg (in terms of solid content) was put into 260 l (liter) of 35% hydrochloric acid housed in a reaction tank (1 tGL reactor), and stirred while maintaining the liquid temperature at 70 ° C. When the phosphor was sufficiently dispersed, 100 l (liter) of 67.5% nitric acid was added to the dispersion at a rate of 100 ml / min, and stirring was continued for another 2 hours. After stirring, the content of iron, copper and chromium contained in the solution was measured,
It contained 430 ppm of iron, 20 ppm of copper, and 90 ppm of chromium. (Acid dissolution step) After adding 200 ml of 31% peroxide water to the solution after stirring and changing the valence of divalent iron ion (Fe ²⁺ ) to trivalent iron ion (Fe ³⁺ ), Further, 600 ml of 28% aqueous ammonia was added to generate iron hydroxide (Fe (OH) ₃ ). Then, lead nitrate 6
0 g is added and mixed to produce lead chromate (PbCrO _4), and hydrogen sulfide gas is introduced at a rate of about 15 l / min for 10 minutes to produce copper sulfide (CuS) and lead sulfide (PbS). I let it. Thereafter, 3 kg of zinc sulfide was added as an adsorbent and mixed well.

The above solution was passed through a continuous centrifugal dehydrator to perform solid / liquid separation to remove solids. The solution was then placed in a reaction vessel and heated to raise the temperature of the solution to 60 ° C. After the temperature was raised, 130 kg of solid oxalic acid was added with stirring, and stirring was further continued for 1 hour. Thereafter, the reaction product was allowed to settle by standing, and the supernatant was removed from the system. Next, p of the supernatant liquid was purified using pure water.
Water washing was repeated until H became 5.0 or more.

The washed reaction product is subjected to settling filtration,
After drying for about 12 hours in an alumina tray, the mixture is roasted at 850 ° C. for 4 hours in a continuous roasting furnace to obtain 89 kg (equivalent to 95.7% of the theoretical yield of 93 kg) of rare earth oxide (Y ₂ O ₃ · Eu
₂ O ₃ ) was obtained. When the contents of iron, copper and chromium in this rare earth oxide were measured, iron 4 ppm, copper 4 ppm, chromium
The content was 3 ppm, which was such that the emission color of other phosphors was not affected.

Next, 35 g of sodium carbonate, 35 g of sulfur, and 8 g of potassium phosphate were added as fluxing agents to 100 g of the obtained rare earth oxide and mixed well. This mixture was filled in a quartz crucible and fired in air at 1150 ° C. for 240 minutes.

The fired product is washed several times with pure water, and then
After washing with a 0.5% mineral acid aqueous solution, the washing is repeated again with pure water until the pH of the supernatant becomes 5.2 or more.
Filtration, drying, sieving to, europium-activated sulfide yttrium phosphor _{(Y 2 O 2 S: Eu} ) was obtained.

When the light emission characteristics (luminance characteristics at the same chromaticity) of the obtained phosphor were examined, as shown in Table 1, the phosphors had characteristics comparable to those of the newly manufactured product (Reference Example).

COMPARATIVE EXAMPLE Europium-activated yttrium oxysulfide phosphor (Y ₂ O ₂ S: Eu) to which a photosensitive resin such as polyvinyl alcohol or dichromate, a pigment, and the like, which were recovered from the coating process of the color CRT fluorescent screen, were adhered. ) 100 kg (in terms of solid content) was put into 260 l of 35% hydrochloric acid accommodated in a reaction tank (1 tGL reactor), and stirred while maintaining the liquid temperature at 70 ° C. When the phosphor is sufficiently dispersed, 67.5%
100 l (liter) of nitric acid was added at a rate of 100 ml / min, and stirring was continued for another 2 hours. After stirring, iron contained in the solution,
When the contents of copper and chromium were measured, iron 430 ppm,
It contained 20 ppm of copper and 90 ppm of chromium.

The above stirred liquid was transferred to a stationary tank and allowed to stand for 24 hours or more, and then the supernatant was filtered through a membrane filter.

The filtrate is placed in a reaction vessel and heated to a temperature of 60 ° C.
After heating to 130 kg of solid oxalic acid with stirring
Was added and stirring was continued for another hour. Thereafter, the reaction product was allowed to settle by standing, and the supernatant was removed from the system.
Next, washing with water was repeatedly performed using pure water until the pH of the supernatant became 5.0 or more.

The washed reaction product was subjected to sedimentation filtration,
After drying for about 12 hours in an alumina tray, the mixture is roasted at 850 ° C. for 4 hours in a continuous roasting furnace to obtain 89 kg (equivalent to 95.7% of the theoretical yield of 93 kg) of rare earth oxide (Y ₂ O ₃ · Eu
₂ O ₃ ) was obtained. When the contents of iron, copper and chromium in the rare earth oxide were measured, they were 15 ppm of iron, 9 ppm of copper, and 11 ppm of chromium, which were the contents affecting the emission color of other phosphors.

Next, 35 g of sodium carbonate, 35 g of sulfur, and 8 g of potassium phosphate were added as fluxing agents to 100 g of the obtained rare earth oxide and mixed well. This mixture was filled in a quartz crucible and fired in air at 1150 ° C. for 240 minutes.

The fired product is washed several times with pure water, and then
After washing with a 0.5% mineral acid aqueous solution, the washing is repeated again with pure water until the pH of the supernatant becomes 5.2 or more.
Filtration, drying, sieving to, europium-activated sulfide yttrium phosphor _{(Y 2 O 2 S: Eu} ) was obtained.

When the light emission characteristics (luminance characteristics at the same chromaticity) of the obtained phosphor were examined, as shown in Table 1, the light emission characteristics were lower than those of Examples and new manufactured products (Reference Examples). Was observed.

[Table 1]

[0055]

As described above, according to the method for producing a rare-earth phosphor of the present invention, the rare-earth phosphor or the rare-earth element ion solution obtained by dissolving it in the rare-earth oxide mineral acid is used. Iron, copper, and chromium metal ions are removed, so the iron, copper, and chromium metal elements can be removed from the rare earth phosphor or its raw material, which contains iron, copper, and chromium metal elements as impurities. It is possible to regenerate or produce a high-purity phosphor containing no phosphor.

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Claims (10)

[Claims] 1. A method for producing a high-purity rare-earth phosphor from a rare-earth phosphor or a rare-earth oxide as a raw material thereof, which comprises at least one of iron, copper and chromium as impurities. Dissolving the rare earth-based phosphor or its rare earth oxide with a mineral acid; (b) forming a precipitate of iron, copper and chromium dissolved in the solution, adsorbing the precipitate to an adsorbent; (C) adding oxalic acid and / or dimethyl oxalate to the solution to form a rare earth oxalate; and (d) heat-treating the rare earth oxalate to form a rare earth oxide. And a step of obtaining a rare earth phosphor. 2. The process of (b), wherein the precipitate of iron, copper and chromium is formed by: (i) adding hydrogen peroxide solution to the solution, then adding ammonia water to neutralize the solution; 2. The method for producing a rare earth phosphor according to claim 1, further comprising: (ii) a step of introducing a hydrogen sulfide gas after adding a nitrate to the solution. 3. The method for producing a rare earth phosphor according to claim 1, wherein the adsorbent is zinc sulfide. 4. The rare earth element according to claim 1, further comprising, after the step (d), a step (e) of adding a flux to the rare earth oxide and firing the rare earth oxide. Method for producing a phosphor. 5. The method for producing a rare-earth phosphor according to claim 1, wherein the mineral acid in the step (a) is hydrochloric acid and / or nitric acid. 6. The method for producing a rare earth phosphor according to claim 1, wherein the heat treatment temperature in the step (c) is 700 ° C. to 1100 ° C. 7. The method according to claim 1, wherein in the step (c), the produced rare earth oxalate is washed with water, filtered, dried, and then subjected to a heat treatment.
The method for producing a rare-earth phosphor according to the above item. 8. The rare earth phosphor according to claim 1, wherein the rare earth phosphor is an oxysulfide rare earth phosphor.
The method for producing a rare-earth phosphor according to the above item. 9. The rare-earth phosphor has a general formula: Re ₂ O ₂ S
(Wherein Re is Y, La, Ce, Pr, Nd, Pm, S
m, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb
And at least two rare earth elements selected from Lu) and Lu).
5. The method for producing a rare earth phosphor according to any one of the above. 10. The method for producing a rare earth phosphor according to claim 9, wherein the rare earth phosphor is a europium-activated yttrium oxysulfide phosphor.