CN102395649A - Red phosphor and method for producing same - Google Patents

Abstract

Disclosed is a red phosphor which is obtained by activating a titanate represented by the following general formula: M2TiO4 (wherein M represents one or more alkaline earth metal elements) with Mn, and has an Si content of not more than 24,000 ppm. The red phosphor can be produced by a process including a step of mixing an alkaline earth metal source, a manganese source and a titanium source, a step of firing the resultant mixture to obtain a fired body, and a step of annealing the thus-obtained fired body. As the above-mentioned metal sources, those metal sources each having such an Si purity that the Si content in the resulting red phosphor is not more than 24,000 ppm are used.

Description

Red phosphor and manufacturing method thereof

technical field

The invention relates to a red phosphor with titanate as the base material and a manufacturing method thereof.

Background technique

In recent years, blue diodes have been put into practical use, and there are many studies on white light-emitting diodes using such diodes as light-emitting sources. Light-emitting diodes have advantages of being lightweight, not using mercury, and having a long life.

For example, a white light-emitting diode in which Y ₃ Al ₅ O ₁₂ :Ce is coated on a blue light-emitting element is known. Strictly speaking, however, this light-emitting diode is not white, but white mixed with green and blue. From this, it has been proposed to adjust the color tone by mixing Y ₃ Al ₅ O ₁₂ :Ce with a red phosphor that absorbs blue light and emits red fluorescence. There are many reports on organic materials but few reports on inorganic materials about red phosphors that absorb blue light and emit red fluorescence.

On the other hand, inorganic materials such as oxide phosphors, oxysulfide phosphors, sulfide phosphors, and nitride phosphors have been proposed as general red phosphors, and phosphors using titanate as a base material have also been proposed. body. For example, Patent Document 1 below proposes a red light-emitting phosphor obtained by adding trivalent Eu to a titanate represented by the general formula M ₂ TiO ₄ (M represents an alkaline earth metal element) and activating it. In addition, it is proposed in the following patent document 2: by the general formula Me ^I _x Me ^II _y Ti _1-a O ₄ X _m : Mn _z (wherein, Me ^I is a divalent or trivalent cation, and Me ^II is a Valence cation, X is Cl or F that can balance the charge, 0≤x≤4, 0≤y≤4, 0≤m≤4, 0≤a≤1, 0<z≤0.5) shown in the red phosphor wait.

These prior art phosphors using titanate as a base material are obtained by mixing an alkaline earth metal source, a titanic acid source, and an activating component in a dry or wet manner to obtain a homogeneous mixture of these raw materials, followed by firing, The obtained red emitter has problems in luminous intensity, and the quantum yield is also low.

prior art literature

patent documents

Patent Document 1: Japanese Patent Laid-Open No. 2006-232948

Patent Document 2: Japanese Unexamined Patent Publication No. 2007-297643

Contents of the invention

The problem to be solved by the invention

Therefore, the present invention provides a red phosphor that emits red light with high luminous intensity upon excitation with blue light, and an industrially advantageous manufacturing method thereof.

solutions to problems

The inventors of the present invention conducted intensive studies in view of such facts, and found that, for a red phosphor activated by adding Mn to a titanate represented by a specific general formula as a base material, impurities have an effect on the emission intensity. make an impact. As a result of further studies, the inventors of the present invention found that the impurity that greatly affects the luminous intensity is Si.

The present invention is based on the aforementioned knowledge, and provides a red phosphor characterized in that,

It is obtained by adding Mn to the titanate represented by the following general formula (1) and activated, and the Si content is 24000ppm or less,

M ₂ TiO ₄ (1)

In the formula, M represents one or more alkaline earth metal elements.

In addition, the present invention provides a method for producing a red phosphor, which is a preferred method for producing the aforementioned red phosphor,

It includes: mixing an alkaline earth metal source, a manganese source and a titanium source, roasting the obtained mixture to obtain a calcined body, and then annealing the calcined body,

The substances used as the above-mentioned respective metal sources have a purity such that the amount of Si contained therein is such that the Si content of the obtained red phosphor is 24000 ppm or less.

The effect of the invention

According to the present invention, it is possible to provide a red phosphor having a high emission intensity of red light. In addition, according to the production method of the present invention, the red phosphor can be produced by an industrially advantageous method.

Description of drawings

Fig. 1 is the fluorescence spectrum (excitation wavelength 460nm) of the red phosphor obtained in Example 1.

Detailed ways

Hereinafter, the present invention will be described based on preferred embodiments.

The red phosphor of the present invention basically emits red light when excited by blue light. Specifically, it is excited at least by excitation light of 270 to 550 nm, preferably 380 to 490 nm. In addition, it has a luminescent band in the region of 600 to 750 nm, preferably 650 to 700 nm (that is, has a red spectrum).

The red phosphor of the present invention is activated by adding Mn to titanate represented by the following general formula (1).

M ₂ TiO ₄ (1)

(In the formula, M represents one or more alkaline earth metal elements.)

M in the general formula (1) is one or two or more alkaline earth metal elements selected from the group consisting of calcium, magnesium, strontium, and barium, and among these, excited by light passing through the wavelength of the blue region, From the viewpoint of efficiently emitting red light, M is preferably magnesium. It should be noted that when M is two or more alkaline earth metal elements, the general formula (1) becomes M ^I _x1 M ^II _x2 ... M ^N _xn TiO ₄ , and X1, X2, ... Xn satisfy X1+X2+...+Xn=2 positive number of .

The Mn for activating titanate is one or more of divalent to tetravalent, and especially tetravalent Mn is preferable from the viewpoint of high intensity of light emission in the red region. The content of activated Mn is preferably 0.01 to 2.5 mol %, particularly preferably 0.25 to 1.0 mol %, in terms of Mn atoms, based on the titanate, from the viewpoint of high luminous efficiency and excellent luminous intensity.

The red phosphor of the present invention is characterized in that it has the aforementioned composition and does not substantially contain Si, specifically, the Si content is 24000 ppm or less. The Si content is preferably 15000 ppm or less, more preferably 100 ppm or less. In the red phosphor of the present invention, since Si is responsible for lowering the emission intensity, the smaller the Si content, the more preferable. Si content can be reduced to about 20ppm at present. Such a level of Si content exhibits sufficiently high luminous intensity.

Inorganic materials conventionally known as red phosphors, represented by red phosphors activated by adding Mn to titanate represented by the general formula (1), generally contain metal sources, etc. of various impurities. However, there has been no report on the impact of impurities on the performance of red phosphors. In particular, the inventors of the present invention studied the performance of a red phosphor obtained by adding Mn to the titanate represented by the general formula (1) and activated it, paying attention to impurities, and found that the impurities affect the luminous intensity. . Further studies have revealed that Si, among the impurities, has a large influence on the luminous intensity. A conventionally known red phosphor obtained by adding Mn to a titanate represented by the general formula (1) and activated (for example, a substance prepared by the method described in Patent Document 2) contains about 25000 ppm of Si . If it is made below 24000ppm according to the method stipulated in the present invention, it is confirmed that there is a significant improvement effect on the luminous intensity.

The Si content in the red phosphor of the present invention can be quantified, for example, by analysis using a fluorescent X-ray analyzer (ZSX100e) manufactured by Rigaku Co., Ltd., using Kα line peak intensity values in the range of 108 to 110 degrees. In addition, although it is not clear, it is considered that in the red phosphor of the present invention, Si exists in the form of Si ⁴⁺ in a solid solution state in the phosphor crystal.

The red phosphor of the present invention is a powder, and its particle shape is not particularly limited. The particle shape may be spherical, polyhedral, spindle, needle, or amorphous, for example. From the viewpoint of further improving the absorption efficiency of excitation light, etc., a spherical shape is preferable.

The average particle diameter of the red phosphor of the present invention is preferably 1 to 30 μm, particularly preferably 10 to 25 μm. If the average particle diameter is less than 1 μm, excitation light is likely to be scattered, and the absorption efficiency of excitation light tends to decrease. If the average particle diameter exceeds 30 μm, the particle surface area tends to be small, and absorption of excitation light also tends to become insufficient. In addition, the average particle diameter mentioned in this invention means the average particle diameter of the secondary particle formed by aggregation of primary particle. This average particle diameter is a median particle diameter. The average particle size (median particle size) of the secondary particles can be measured, for example, by a laser diffraction/scattering particle size distribution analyzer (model LA920) manufactured by Horiba Manufacturing Co., Ltd., with the refractive index of the sample being 1.81 and the refractive index of the dispersion medium 1.33, calculated on a volume basis.

The average particle diameter can be adjusted as follows, for example. That is, the calcined body obtained by the calcination process described later is pulverized by an automatic mortar or ball mill, and classified using a sieve having a mesh size corresponding to the target particle diameter as the case may be, so that a product having a desired average particle diameter can be obtained. powder.

The BET specific surface area of the red phosphor of the present invention is preferably 0.05 to 1.0 m ² /g, particularly preferably 0.1 to 0.5 m ² /g. If the BET specific surface area is less than 0.05 m ² /g, the absorption of excitation light tends to be insufficient. If the BET specific surface area exceeds 1.0 m ² /g, the average particle diameter is small due to the large surface area, and therefore the excitation light may be scattered and the absorption of the excitation light may become insufficient. The BET specific surface area can be measured, for example, using a BET method Monosorb specific surface area measuring device (Flow Sorb II 2300) manufactured by Shimadzu Corporation.

The BET specific surface area can be adjusted as follows, for example. That is, the calcined body obtained in the calcination process described later is pulverized with an automatic mortar or ball mill, and classified using a sieve with a mesh size corresponding to the target particle size as the case may be, so that a desired BET specific surface area can be obtained. powder.

Next, a preferred production method of the red phosphor of the present invention will be described.

The manufacturing method of the red phosphor of the present invention includes the steps of mixing an alkaline earth metal source, a manganese source and a titanium source, firing the obtained mixture to obtain a fired body, and then annealing the fired body. That is, the manufacturing method of the red phosphor of this invention roughly divides and includes (a) mixing process, (b) firing process, and (c) annealing process process.

(a) In the mixing step, an alkaline earth metal source, a manganese source, and a titanium source are uniformly mixed to prepare a uniform mixture.

As the alkaline earth metal source of the first raw material, for example, oxides, hydroxides, carbonates, nitrates, sulfates, organic acid salts and the like of alkaline earth metals can be used. One or two or more of these compounds can be used. Among these, hydroxides are preferred from the viewpoint that no impurities remain after firing and the viewpoint of high reactivity between raw materials. The alkaline earth metal source is used not in a solution state such as an aqueous solution but in a solid (powder) state. As an alkaline earth metal source, it is preferable to use a thing whose average particle diameter is 5 micrometers or less, especially 0.2-2 micrometers from a viewpoint which can mix uniformly easily.

As the manganese source of the second raw material, for example, manganese oxides, hydroxides, carbonates, nitrates, sulfates, organic acid salts and the like can be used. One or two or more of these compounds can be used. Among these, manganese carbonate is preferable from the viewpoint of not remaining impurities after firing and the viewpoint of easy solid solution in the matrix composition. The manganese source is also used in a solid (powder) state. As a manganese source, it is preferable to use what has an average particle diameter of 10 micrometers or less, especially 1-9 micrometers from a viewpoint which can mix uniformly easily.

As the titanium source of the third raw material, for example, titanium oxides, hydroxides, halides, alkoxide compounds and the like can be used. One or two or more of these compounds can be used. Among these, titanium oxide (TiO ₂ ) is preferable from the viewpoint that no impurities remain after firing and that it is relatively easy to obtain. Titanium oxide (TiO ₂ ) used may be obtained by a sulfuric acid method or a chlorine method, and an anatase type or rutile type may be used without particular limitation. In addition, the titanium source is also used in a solid (powder) state. As a titanium source, it is preferable to use a thing whose average particle diameter is 5 micrometers or less, especially 0.2-2 micrometers from a viewpoint which can mix uniformly easily.

As described above, the red phosphor of the present invention does not substantially contain Si, and specifically, has a Si content of 24000 ppm or less. Therefore, in the mixing step, the substances used as the above-mentioned respective metal sources have such high purity that the amount of Si contained in them is such that the Si content of the obtained red phosphor is 24000 ppm or less.

The inventors of the present invention found that Si mixed into the red phosphor is mainly derived from a titanium source (for example, titanium oxide) as a raw material. In the present invention, as the titanium source used, it is preferable to use a high-purity material having a Si content of 9000 ppm or less, particularly 6000 ppm or less, especially 100 ppm or less. As a titanium source of a raw material, a commercially available item can be used. Among commercial products, it is preferable to select and use the above-mentioned high-purity titanium source.

As for the alkaline earth metal source and the manganese source, it is preferable to use a high-purity material with a low Si content similarly to the titanium source. However, alkaline earth metal sources and manganese sources are generally lower in Si content than titanium sources and therefore generally do not pose a problem in the present invention. It is preferable to use a pure earth metal source with a Si content of 100 ppm or less, and a manganese source with a Si content of 100 ppm or less. As for the alkaline earth metal source and the manganese source, even general commercial products can satisfy these Si contents.

In terms of the mixing ratio of the alkaline earth metal source and the titanium source, the alkaline earth metal atom (M) in the alkaline earth metal source is relative to the titanium atom (Ti ) molar ratio (M/Ti) is preferably 1.6 to 2.5, particularly preferably 1.8 to 2.2.

On the other hand, the mixing ratio of the manganese source is preferably 0.01 to 3 mol % of Mn atoms with respect to the obtained titanate, particularly preferably 0.1～1.5mol%.

Although the Si content in the finally obtained red phosphor is also affected by the specific types of metal sources used, if the aforementioned preferred purity metal sources and preferred mixing ratios are used, the red phosphor can generally be made Si content is 24000ppm or less.

The method of mixing the alkaline earth metal source, the manganese source and the titanium source of the first to third raw materials may be either a wet method or a dry method, but from the viewpoint of being able to easily obtain a homogeneous mixture in which each raw material is uniformly mixed, it is preferable It is carried out in a wet method by mechanical means. In particular, a uniform mixture can be obtained more easily by using a media mill (media mill), which is a machine capable of pulverizing and mixing at the same time, by a wet method. In addition, the luminescence of the red phosphor obtained by using this uniform mixture Very high strength.

The mixing process using a media mill is further explained.

The mixing treatment in the media mill basically includes a slurry preparation step and a mixing step of introducing the obtained slurry into the media mill and performing mixing treatment.

In the slurry preparation process, the alkaline earth metal source, the manganese source, and the titanium source are dispersed in a dispersion medium to prepare a slurry. As the dispersion medium, any of water and non-aqueous dispersion media can be used. From the viewpoint of ease of handling, etc., it is preferable to use water as the dispersion medium.

From the viewpoint of small processing scale and easy operability, the solid content concentration of the slurry (total concentration of alkaline earth metal source, manganese source and titanium source) is preferably 5 to 40% by weight, particularly preferably 10 to 30% by weight.

A dispersant may be added to the slurry. By adding a dispersant, the alkaline earth metal source, the manganese source and the titanium source can be more uniformly dispersed in the dispersion medium. As a result, a homogeneous mixture of these raw materials can be more easily obtained. What is necessary is just to select a suitable dispersing agent according to the kind of dispersion medium as the dispersing agent used. When the dispersion medium is water, various surfactants, polycarboxylate ammonium salts, and the like can be used as the dispersant. From the viewpoint of sufficient dispersion effect, the concentration of the dispersant in the slurry is preferably 0.01 to 10% by weight, particularly preferably 1 to 5% by weight.

It should be noted that, for the dispersion medium and dispersant used in the preparation of the slurry, it is also preferable to use a substance with as little Si content as possible, but usually as long as the above-mentioned dispersion medium and dispersant are used, there will be no damage to the red phosphor. Si in an amount affecting the luminous intensity is mixed into the red phosphor from the above-mentioned dispersion medium and dispersant. In addition, in the production method of the present invention, there is no factor causing Si to be mixed to an extent that affects the emission intensity of the red phosphor other than each metal source, dispersion medium, and dispersant used for slurry preparation.

Next, a homogeneous mixture is obtained by introducing the slurry obtained in the slurry preparation step into a media mill and performing mixing treatment. As the media mill, a bead mill, a ball mill, a paint shaker, an attritor, a sand mill, or the like can be used. Particular preference is given to using a bead mill. In this case, the operating conditions, the type and size of beads can be appropriately selected according to the size of the device, the throughput, the types of alkaline earth metal source, manganese source, and titanium source, and the like.

From the viewpoint of obtaining a more uniform mixture, the mixing treatment by the wet method is preferably performed until the average particle diameter of the solid matter (average particle diameter of secondary particles) becomes 0.05 to 1 μm, particularly preferably 0.1 to 0.5 μm.

After the mixing process, the homogeneous mixture is recovered from the slurry by filtration. The recovered homogeneous mixture is preferably dried in advance before being delivered to the (b) roasting step. The drying treatment can be performed at 80 to 200° C. for 1 to 100 hours, for example.

Next, the homogeneous mixture obtained in the (a) mixing step is passed to the (b) firing step to obtain a fired body. In terms of firing conditions, the firing temperature is preferably 1150 to 1600°C, particularly preferably 1200 to 1350°C. If the calcination temperature is lower than 1150°C, it is difficult to obtain the matrix crystal in a single phase, and the luminescent ions are difficult to dissolve; on the other hand, if the calcination temperature exceeds 1600°C, the sintering between the particles is excessive and it is difficult to obtain a powder. tendency. The firing time is 1 hour or more, particularly preferably 3 to 20 hours. The firing atmosphere is not particularly limited, and may be either an oxidizing gas atmosphere such as air or an inert gas atmosphere.

The obtained calcined body is crushed to a desired particle size as necessary, and is delivered in a powder state to the subsequent annealing process. Baking can be performed several times as desired. Alternatively, for the purpose of making the characteristics of the powder uniform, the article obtained by firing once may be crushed, followed by firing again. In addition, before performing the annealing treatment step, if necessary, classification or the like may be performed in advance to adjust the particle size characteristics.

Next, the fired body obtained in the (b) firing step is passed to the (c) annealing step to obtain the red phosphor of the present invention. By performing this annealing treatment, the emission intensity can be significantly increased. The reason why the luminescence intensity is increased by performing this annealing treatment is not clear, but it is considered that the structure of the matrix crystal is changed from cubic to tetragonal to efficiently convert light energy absorbed by luminescent ions into luminescence.

Regarding the conditions of the annealing treatment, the treatment temperature is preferably 500 to 800°C, particularly preferably 570 to 690°C. The reason for this is that if the annealing temperature is less than 500°C, no crystal change occurs; on the other hand, if the annealing temperature exceeds 800°C, the cubic crystal tends to return again. The annealing treatment time is preferably 1 hour or more, particularly preferably 3 to 24 hours. The atmosphere of the annealing treatment is not particularly limited, and may be any of an oxidizing atmosphere such as oxygen or air, or an inert gas atmosphere. In addition, multiple times of annealing may be performed as needed.

The annealed red phosphor may also be crushed to a desired particle size or classified as necessary.

The red phosphor obtained in this way can be applied to displays such as field emission displays, plasma displays, and electroluminescence. In addition, since it has an excitation spectrum around 460 nm, it is suitable for use as a phosphor for blue LED excitation. It is particularly suitable for use in electroluminescent displays. In addition, by a method of using in combination with a blue-excited green phosphor, a method of using in combination with a blue LED element and a blue-excited green phosphor, or a method of using in combination with a blue LED element and a blue-excited yellow-emitting phosphor method, etc., and thus can also be applied to white LEDs.

Example

The present invention is illustrated by examples below, but the present invention is not limited to these examples.

The Si content, average particle size, and BET specific surface area in the following examples and comparative examples were measured as follows.

Si content: using a fluorescent X-ray analyzer (ZSX100e) manufactured by Rigaku Co., Ltd., it was analyzed and quantified using the Kα line peak intensity value in the range of 108 to 110 degrees.

Average particle diameter: Measured with a laser diffraction/scattering particle size distribution analyzer (model LA920) manufactured by Horiba, and calculated on a volume basis with the refractive index of the sample being 1.81 and the refractive index of the dispersion medium being 1.33.

BET specific surface area: Measured using a BET method Monosorb specific surface area measuring device (Flow Sorb II 2300) manufactured by Shimadzu Corporation.

[Example 1]

Magnesium hydroxide (average particle size 0.57 μm), titanium oxide (average particle size 0.64 μm) with a Si content of 4676 ppm, and manganese carbonate (average particle size 5.2 μm) according to the molar ratio of magnesium: titanium: manganese is 2: 0.996 : 0.004 and weighed into the tank. Water and a dispersant (Pois 2100, manufactured by Kao Corporation) were added to the tank to prepare a slurry having a solid content concentration of 15% by weight. The concentration of the dispersant was 2.0% by weight.

While stirring the slurry, ball milling was performed for 150 minutes using zirconia balls with a diameter of 2.0 mm to perform mixing and pulverization by a wet method. The average particle diameter of the raw material mixture in the mixed and pulverized slurry was measured by a light scattering method and found to be 0.5 μm.

Next, the mixture was collected by filtration from the slurry, dried at 120° C. for 10 hours, and a dry powder was obtained. The dry powder had an average particle diameter of 0.5 μm and an angle of repose of 45°.

Next, the dry powder was put into an electric furnace, and baked at 1250° C. for 5 hours in a static state in the atmosphere. Next, the baked powder was once returned to room temperature (20° C.), and then annealed at 600° C. for 16 hours in an oxygen atmosphere.

The annealed powder was analyzed based on X-ray diffraction measurement. According to the analysis results, it was confirmed that the obtained powder was Mg ₂ TiO ₄ :0.4 mol% Mn ⁴⁺ .

[Comparative example 1]

Using titanium oxide (average particle size: 0.64 μm, BET specific surface area: 6.7 m ² /g) with a Si content of 9351 ppm instead of titanium oxide used in Example 1, according to the same operation and conditions as in Example 1. A powder was obtained. The same analysis as in Example 1 was performed on the obtained powder. The analysis results were the same as in Example 1, and it was confirmed that the obtained powder was Mg ₂ TiO ₄ :0.4 mol% Mn ⁴⁺ .

<Measurement of Si content, average particle size and BET specific surface area>

For the phosphor samples obtained in Example 1 and Comparative Example 1, Si content, average particle diameter, and BET specific surface area were measured. The measurement results are shown in Table 1.

<Evaluation of fluorescence characteristics>

For the phosphor samples obtained in Example 1 and Comparative Example 1, the maximum wavelength of the emission spectrum at an excitation wavelength of 460 nm, the emission intensity at the maximum wavelength, and the CIE chromaticity were measured. The measurement results are shown in Table 1. Note that the emission intensity at the maximum wavelength is expressed as a relative intensity value when the emission intensity of the phosphor sample of Comparative Example 1 is set to 100. In addition, FIG. 1 shows the fluorescence spectrum of the phosphor sample obtained in Example 1. As shown in FIG.

The measurement of the emission spectrum and CIE chromaticity was performed as follows.

Luminescence Spectrum: Using a fluorescence spectrophotometer (manufactured by Hitachi High-Technologies Corporation), the excitation light was 460 nm, and the range from 430 to 800 nm was scanned to obtain a spectrum.

CIE chromaticity: According to the relative value of the fluorescence spectrum at the excitation wavelength of 460nm and in accordance with JIS Z 8701, the xy colorimetric coordinates are obtained.

[Example 2]

A powder was obtained by the same operation and conditions as in Example 1 except that titanium oxide (average particle diameter: 0.64 μm) having a Si content of 9.4 ppm was used instead of the titanium oxide used in Example 1. The same analysis as in Example 1 was performed on the obtained powder. The analysis results were the same as in Example 1, and it was confirmed that the obtained powder was Mg ₂ TiO ₄ :0.4 mol% Mn ⁴⁺ . About the obtained powder, it carried out similarly to Example 1, and carried out the measurement of Si content, average particle diameter, and BET specific surface area, and the evaluation of fluorescence characteristic. The results are shown in Table 1.

Table 1

It is evident from the description in Table 1 that the Si content affects the luminous intensity of the red phosphor. When the Si content is 24000ppm or less, it is confirmed that there is an improvement effect on the luminous intensity; when the Si content is 15000ppm or less (Example 1), especially 100ppm or less (Example 2), then it is confirmed that there is an extremely high improvement effect.

Claims (11)

1. A red phosphor, characterized in that, It is obtained by adding Mn to the titanate represented by the following general formula (1) and activated, and the Si content is 24000ppm or less, M ₂ TiO ₄ (1) In the formula, M represents one or more alkaline earth metal elements. 2. The red phosphor according to claim 1, which emits light with excitation light of 270 to 550 nm. 3. The red phosphor according to claim 1 or 2, which has a luminescence band in a region of 600 to 750 nm. 4. The red phosphor according to any one of claims 1 to 3, wherein M in the general formula (1) is Mg. 5. The red phosphor according to any one of claims 1 to 4, which has an average particle diameter of 1 to 30 μm. 6. A method for producing a red phosphor, characterized in that, It is the method for manufacturing the red phosphor described in claim 1, It includes: mixing an alkaline earth metal source, a manganese source and a titanium source, roasting the obtained mixture to obtain a calcined body, and then annealing the calcined body, The substances used as the respective metal sources have a purity such that the amount of Si contained therein is such that the Si content of the obtained red phosphor is 24000 ppm or less. 7. The method for producing a red phosphor according to claim 6, wherein the Si content of the titanium source is 9000 ppm or less. 8. The method for producing a red phosphor according to claim 6 or 7, wherein the mixing of the alkaline earth metal source, the manganese source, and the titanium source is performed by a wet method. 9. The method for producing a red phosphor according to any one of claims 6 to 8, wherein the firing temperature is 1150 to 1600°C. 10. The method for producing a red phosphor according to any one of claims 6 to 9, wherein the temperature of the annealing treatment is 500 to 800°C. 11. The method for producing a red phosphor according to claim 6, wherein the titanium source is titanium dioxide.

Images