KR20110138370A - Red phosphor and method for producing same - Google Patents

Abstract

The present invention relates to a red phosphor obtained by reactivating Mn on a titanate represented by the formula M ₂ TiO ₄ (wherein M represents one or two or more alkaline earth metal elements), wherein the Si content is 24000 ppm or less. do. Such a red phosphor includes a step 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, which is included in each of these metal sources. The amount of Si to be manufactured can be manufactured by using what has the purity of the quantity whose Si content of the red fluorescent substance obtained becomes 24000 ppm or less.

Description

Red phosphor and manufacturing method thereof {RED PHOSPHOR AND METHOD FOR PRODUCING SAME}

The present invention relates to a red phosphor based on titanate and a method for producing the same.

Recently, blue diodes have been put into practical use, and there are many studies on white light emitting diodes using this diode as a light emitting source. The light emitting diode has the advantage of being lightweight, using no mercury and having a long lifetime.

For example, a white light emitting diode having Y ₃ Al ₅ O ₁₂ : Ce coated on a blue light emitting element is known. However, this light emitting diode is not strictly white but becomes white mixed with cyan. _{Therefore, Y 3 Al 5 O 12:} Ce and, by absorbing the blue light and mix the red phosphor emitting red fluorescent light, it is proposed to adjust the color tone. There are many reports on red phosphors that absorb blue light and emit red fluorescence, but little on inorganic materials.

On the other hand, as a general red phosphor, inorganic materials such as an oxide phosphor, an oxysulfide phosphor, a sulfide phosphor and a nitride phosphor have been proposed, and a phosphor having a titanate as a base material has also been proposed. For example, Patent Document 1 below discloses a chemical formula; A red light-emitting phosphor obtained by activating trivalent Eu to a titanate represented by M ₂ TiO ₄ (M represents an alkaline earth metal element) has been proposed. In addition, Patent Document 2, 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, Me ^II is a monovalent cation, X is a charge Is a balanced Cl or F, and 0? X? 4, 0? Y? 4, 0? M? 4, 0? A? 1, and 0 <z? 0.5.

Phosphors based on titanates in these prior arts are obtained by mixing an alkaline earth metal source, a titanic acid source and an activating component in a dry or wet manner, obtaining a homogeneous mixture of these raw materials, and then firing the same. The light emitter had a problem in the light emission intensity and had a low quantum yield.

Japanese Patent Laid-Open No. 2006-232948 Japanese Patent Laid-Open No. 2007-297643

Accordingly, the present invention provides a red phosphor that is excited with blue light and emits red light with high emission intensity, and an industrially advantageous manufacturing method thereof.

As a result of intensive studies in this situation, the present inventors found that in a red phosphor obtained by regenerating Mn with a titanate represented by a specific chemical formula, impurities affect emission intensity. As a result of further studies, the inventors found that the impurity which greatly affects the luminescence intensity is Si.

The present invention has been made on the basis of the above findings, and is made by activating Mn in the titanate represented by the following formula (1), and providing a red phosphor characterized in that the Si content is 24000 ppm or less.

(Wherein M represents one or two or more alkaline earth metal elements)

In addition, the present invention is a preferred method for producing the red phosphor, the alkaline earth metal source, manganese source and titanium source is mixed, and the resulting mixture is calcined to obtain a fired body, and then annealing treatment of the fired body It is to provide the manufacturing method of the red fluorescent substance characterized by using as said each metal source the quantity of Si contained in these having the purity of the quantity whose Si content of the red fluorescent substance obtained becomes 24000 ppm or less. .

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

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

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated based on the preferable embodiment.

The red phosphor of the present invention basically excites blue light and emits red light. Specifically, excitation is carried out by excitation light of at least 270 to 550 nm, preferably 380 to 490 nm. It also has a luminous band in the region of 600 to 750 nm, preferably 650 to 700 nm (ie has a red spectrum).

In the red phosphor of the present invention, Mn is revived in the titanate represented by the following formula (1).

<Formula 1>

(Wherein M represents one or two 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, M is magnesium excited by light having a wavelength in the blue region and efficiently It is preferable at the point which emits red light. In addition, when M is 2 or more types of alkaline earth metal elements, Chemical Formula 1 becomes M ^I _x1 M ^II _x2 ... M ^N _xn TiO ₄ , and X1, X2, ... Xn represents X1 + X2 + ... A positive number satisfying Xn = 2.

Mn which is revived by titanate is one kind or two or more kinds of divalent to tetravalent, and in particular, tetravalent Mn is preferable in that the intensity of light emission in red region is high. The content of Mn to be activated is preferably from 0.01 to 2.5 mol%, particularly from 0.25 to 1.0 mol%, as the Mn atom with respect to the titanate from the viewpoint of high luminous efficiency and excellent luminous intensity.

In addition to having the above composition, the red phosphor of the present invention is characterized by being substantially free of Si, specifically, having a Si content of 24000 ppm or less. It is preferable that it is 15000 ppm or less, and, as for Si content, it is more preferable that it is 100 ppm or less. In the red phosphor of the present invention, since Si causes a decrease in luminescence intensity, the smaller the Si content is, the more preferable. Si content can be reduced to about 20 ppm at present. If the Si content is at this level, the emission intensity is sufficiently high.

Inorganic materials conventionally known as red phosphors, including red phosphors obtained by activating Mn on titanate represented by the formula (1), generally contain various impurities derived from a metal source or the like as a raw material. However, there have been no reports on the effect of impurities on the performance of the red phosphor. The inventors of the present invention have focused on the performance of a red phosphor obtained by activating Mn in the titanate represented by the formula (1), and have focused on impurities, and have found that the impurities affect the luminescence intensity. Furthermore, when the examination was advanced, it turned out that Si has a big influence on luminescence intensity among impurities. The red fluorescent substance (for example, what was manufactured by the method of patent document 2) formed by reviving Mn to the titanate represented by General formula (1) known conventionally contains about 25000 ppm of Si. If this is 24000 ppm or less as defined in the present invention, a clear improvement effect on the luminescence intensity is recognized.

Si content in the red fluorescent substance of this invention can be analyzed and quantified by K alpha ray peak intensity value in the range of 108-110 degree using the fluorescent X-ray analyzer (ZSX100e) by the Rigaku Corporation, for example. Although not clear, in the red phosphor of the present invention, Si is considered to exist in a state, which employs as the Si ^{+ 4,} the phosphor crystals.

The red phosphor of the present invention is powder, and its particle shape is not particularly limited. The particle shape may be irregular, for example, in addition to spherical shape, polyhedron shape, fusiform shape, and needle shape. In terms of further improved absorption efficiency of the excitation light, spherical shape is preferable.

It is preferable that the red fluorescent substance of this invention is 1-30 micrometers, especially 10-25 micrometers. When the average particle diameter is less than 1 µm, the excitation light tends to be scattered, and the absorption efficiency of the excitation light tends to be lowered. If the average particle diameter is more than 30 µm, the particle surface area becomes small, and still, absorption of excitation light tends to be insufficient. In addition, all the average particle diameters referred to in the present invention are average particle diameters of secondary particles formed by aggregation of primary particles. The average particle diameter is the median diameter. The average particle diameter (median diameter) of a secondary particle is measured, for example with the Horiba Seisakusho laser diffraction / scattering particle size distribution analyzer (model number LA920), and the refractive index of a sample is 1.81 and the refractive index of a dispersion medium is 1.33 on a volume basis. Can be calculated.

An average particle diameter can be adjusted as follows, for example. That is, a powder having a desired average particle size is obtained by subjecting the fired body obtained in the firing step described later to automatic grinding or ball milling and the like, and in some cases classifying using a sieve of a mesh having a target particle size. Can be.

The red phosphor of the present invention preferably has a BET specific surface area of 0.05 to 1.0 m 2 / g, particularly 0.1 to 0.5 m 2 / g. If the BET specific surface area is less than 0.05 m 2 / g, absorption of the excitation light tends to be insufficient. If the BET specific surface area is more than 1.0 m 2 / g, the average particle diameter is small due to the large surface area, so that the excitation light may scatter and the absorption of the excitation light may be insufficient. BET specific surface area can be measured using the BET method monosorb specific surface area measuring apparatus (flowsorb II 2300) by Shimadzu Corporation.

The BET specific surface area can be adjusted as follows, for example. That is, a powder having a desired BET specific surface area is obtained by subjecting the fired body obtained in the firing step described later to automatic grinding or grinding by ball mill or the like, and in some cases by using a sieve of a mesh having a target particle size. You can get it.

Next, the preferable manufacturing method of the red fluorescent substance of this invention is demonstrated.

The method for producing a red phosphor of the present invention includes a step 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 fluorescent substance of this invention is largely divided, and includes the (a) mixing process, (b) baking process, and (c) annealing process process.

In the mixing step (a), a homogeneous mixture in which the alkaline earth metal source, the manganese source and the titanium source are uniformly mixed is produced.

As the alkaline earth metal source of the first raw material, oxides, hydroxides, carbonates, nitrates, sulfates, organic acid salts and the like of alkaline earth metals can be used, for example. These compounds can use 1 type (s) or 2 or more types. Among these, a hydroxide is preferable at the point that an impurity does not remain after baking and the reactivity of raw materials is high. The alkaline earth metal source is used in a solid (powder) state rather than in a state of a solution such as an aqueous solution. As an alkaline earth metal source, when an average particle diameter is 5 micrometers or less, especially 0.2-2 micrometers, it is preferable from a viewpoint that uniform mixing becomes easy.

As the manganese source of the second raw material, for example, oxides of manganese, hydroxides, carbonates, nitrates, sulfates, organic acid salts and the like can be used. These compounds can use 1 type (s) or 2 or more types. Among these, manganese carbonate is preferable in that impurities do not remain after firing and are easily dissolved in terms of the mother composition. Manganese is also used in a solid (powder) state. As a manganese source, when an average particle diameter is 10 micrometers or less, especially 1-9 micrometers, it is preferable from a viewpoint that uniform mixing becomes easy.

As a titanium source of a 3rd raw material, the oxide, hydroxide, halide, alkoxide compound, etc. of titanium can be used, for example. These compounds can use 1 type (s) or 2 or more types. Among these, titanium oxide (TiO ₂ ) is preferable in that impurities do not remain after firing and are readily available. The titanium oxide (TiO ₂ ) to be used may be obtained by the sulfuric acid method or the chlorine method, and may be used without particular limitation, even if it is an anatase type or a routine type. In addition, a titanium source is used in a solid (powder) state. As a titanium source, when an average particle diameter uses 5 micrometers or less, especially 0.2-2 micrometers, it is preferable from a viewpoint that uniform mixing becomes easy.

As above-mentioned, the red fluorescent substance of this invention does not contain Si substantially, Specifically, Si content is 24000 ppm or less. Therefore, in the mixing step, as the metal sources described above, those having a high purity of an amount such that the Si content of the red phosphor obtained by the amount of Si contained in these are 24000 ppm or less are used.

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

Also for the alkaline earth metal source and the manganese source, it is preferable to use a high-purity one having a low Si content similarly to the titanium source. Especially, since Si content of an alkaline earth metal source and a manganese source is generally low compared with a titanium source, it does not usually become a problem in this invention. It is preferable to use Si of 100 ppm or less with respect to alkaline earth metal sources, and 100 ppm or less of Si content with respect to a manganese source, respectively. About alkaline earth metal sources and manganese sources, even if it is a general commercial item, these Si content can be satisfied.

The mixing ratio of the alkaline earth metal source and the titanium source is 1.6 to 2.5, in particular 1.8 to 2.2, in the molar ratio (M / Ti) of the alkaline earth metal atom (M) in the alkaline earth metal source to the titanium atom (Ti) in the titanium source. It is preferable from the viewpoint of obtaining the single crystal particles and having the best internal quantum efficiency.

On the other hand, the mixing ratio of manganese source is preferably 0.01 to 3 mol%, particularly 0.1 to 1.5 mol%, based on the titanate obtained from the viewpoint of sufficiently absorbing excitation light and excellent in light conversion efficiency.

Although the Si content in the red fluorescent substance finally obtained is influenced also by the specific kind of each metal source to be used, if the metal source of the preferable purity mentioned above and a preferable mixing ratio are employ | adopted, the Si content of a red fluorescent substance will usually be 24000 ppm or less. Can be.

As a method of mixing the alkaline earth metal source, manganese source, and titanium source of the first to third raw materials, both a wet method and a dry method are possible, but performing a wet method by mechanical means is a uniform mixture in which each raw material is uniformly mixed. It is preferable in that it can obtain easily. In particular, by performing a mixing process by a wet method with a media mill, which is a device capable of simultaneously grinding and mixing, a homogeneous mixture can be obtained more easily, and the red phosphor obtained by using the homogeneous mixture has a particularly high luminescence intensity.

The mixing process using a media mill will be further described.

The mixing treatment in the media mill basically consists of a slurry manufacturing step and a mixing step in which the obtained slurry is introduced into the media mill and mixed.

In the slurry manufacturing step, an alkaline earth metal source, a manganese source, and a titanium source are dispersed in a dispersion medium to obtain a slurry. As the dispersion medium, any of water and non-aqueous dispersion medium can be used. In view of ease of handling, water is preferably used as the dispersion medium.

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

You may add a dispersing agent to a slurry. By the addition of the dispersant, the alkaline earth metal source, the manganese source and the titanium source are dispersed more uniformly in the dispersion medium. As a result, a homogeneous mixture of these raw materials can be obtained more easily. The dispersant to be used can select an appropriate thing according to the kind of dispersion medium. When the dispersion medium is water, various surfactants, ammonium polycarboxylic acid salts and the like can be used as the dispersant. The concentration of the dispersant in the slurry is preferably 0.01 to 10% by weight, particularly 1 to 5% by weight, in view of sufficient dispersing effect.

In addition, although it is preferable to use the thing with smallest Si content also about the dispersion medium and dispersant used for manufacture of a slurry, as long as the said dispersion medium and a dispersing agent are used, the quantity of Si which affects the luminescence intensity of a red fluorescent substance, It does not originate in these and mix in red fluorescent substance. In addition, in the manufacturing method of this invention, in addition to each metal source, a dispersion medium, and a dispersing agent used for slurry manufacture, there is no factor in which Si of the grade which affects the light emission intensity of a red fluorescent substance is mixed.

Subsequently, the slurry obtained in the slurry production process is introduced into a media mill to perform a mixing treatment to obtain a homogeneous mixture. As the media mill, bead mills, ball mills, paint shakers, attritors, sand mills and the like can be used. In particular, it is preferable to use a bead mill. In that case, the operation conditions and the type and size of the beads can be appropriately selected according to the size and throughput of the apparatus, the type of alkaline earth metal source, manganese source and titanium source, and the like.

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

After the mixing treatment, the homogeneous mixture is recovered by filtration from the slurry. It is preferable to perform a drying process of the collect | recovered homogeneous mixture before adding to the baking process of (b). Drying process can be performed, for example at 80-200 degreeC for 1 to 100 hours.

Next, the homogeneous mixture obtained at the mixing process of (a) is added to the baking process of (b) to obtain a fired body. As for baking conditions, it is preferable that baking temperature is 1150-1600 degreeC, especially 1200-1350 degreeC. If the firing temperature is less than 1150 ° C., the parent crystal is hardly obtained in a single phase, and the luminescence ions are difficult to solidify. On the other hand, if the firing temperature exceeds 1600 ° C., the sintering of the particles proceeds excessively, so that it is difficult to obtain powder. . The firing time is preferably 1 hour or more, particularly 3 to 20 hours. The atmosphere of firing is not particularly limited, and may be either an oxidizing gas atmosphere such as air or an inert gas atmosphere.

The obtained fired body is disintegrated to a desired particle size as needed and added to the next annealing treatment process in the state of powder. Firing may be carried out as many times as desired. Alternatively, for the purpose of making the characteristics of the powder uniform, it is also possible to disintegrate the one fired, and then refire it. Moreover, prior to performing an annealing process, you may classify etc. previously and may adjust a particle size characteristic as needed.

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

As for the conditions of annealing treatment, it is preferable that treatment temperature is 500-800 degreeC, especially 570-690 degreeC. This is because when the annealing treatment temperature is less than 500 ° C., no crystal change occurs, while when the annealing treatment temperature exceeds 800 ° C., it tends to return to cubic crystal again. The annealing treatment time is preferably 1 hour or more, particularly 3 to 24 hours. The atmosphere of the annealing treatment is not particularly limited, and may be either an oxidizing atmosphere such as oxygen or the atmosphere or an inert gas atmosphere. In addition, annealing process can be performed as many times as needed.

The red phosphor after the annealing treatment may be pulverized, classified, or the like, to a desired particle size as necessary.

The red phosphor obtained in this way can be used, for example, for the use of display devices, such as an electrolytic radiation display, a plasma display, and electroluminescence. Moreover, since it has an excitation spectrum close to around 460 nm, it can apply to the use of the fluorescent substance for blue LED excitation. It is especially suitable for the use of the electroluminescent display device. In addition, the present invention can be applied to white LEDs by a method using in combination with a blue excitation green phosphor, a method using a blue LDE element in combination with a blue excitation green phosphor, or a method using a blue LDE element in combination with a blue excitation yellow light emitting phosphor. It may be.

[Example]

Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples.

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

Si content: It analyzed by the K-ray peak intensity value in the range of 108-110 degree using the fluorescence X-ray analyzer (ZSX100e) by the Rigaku Corporation, and quantified.

Average particle diameter: It measured with the Horiba Seisakusho laser diffraction / scattering particle size distribution measuring apparatus (model number LA920), and computed the refractive index of a sample on the basis of volume as 1.81 and the refractive index of 1.33 of a dispersion medium.

BET specific surface area: It measured using the BET method monosorb specific surface area measuring apparatus (flowsorb II 2300) by Shimadzu Corporation.

EXAMPLE 1

Magnesium hydroxide (average particle diameter: 0.57 µm), titanium oxide having an Si content of 4676 ppm (average particle diameter: 0.64 µm), and manganese carbonate (average particle diameter: 5.2 µm) so that the molar ratio of magnesium: titanium: manganese is 2: 0.996: 0.004. Weighed into the tank. Water and a dispersant (Cao Co., Ltd. poise 2100) were added to the tank, and the slurry which solid content concentration was 15 weight% was prepared. The concentration of the dispersant was 2.0% by weight.

While the slurry was stirred, the ball milling was performed for 150 minutes using a zirconia ball having a diameter of 2.0 mm, thereby performing mixed grinding by the wet method. It was 0.5 micrometer when the average particle diameter of the raw material mixture in the slurry after mixed grinding was measured by the light scattering method.

Subsequently, the mixture was collected by filtration from the slurry, and dried at 120 ° C. for 10 hours to obtain a dry powder. The average particle diameter of dry powder was 0.5 micrometer, and the angle of repose was 45 degrees.

Subsequently, dry powder was put into an electric furnace, and baked at 1250 degreeC for 5 hours in the atmosphere under air | atmosphere. Subsequently, the calcined powder was once returned to room temperature (20 ° C) and then annealed at 600 ° C for 16 hours under oxygen atmosphere.

The powder after the annealing treatment was analyzed by X-ray diffraction measurement. From the analysis results, the obtained powder was confirmed to be Mg ₂ TiO ₄ : 0.4 mol% Mn ^{4 +} .

[Comparative Example 1]

Instead of the titanium oxide used in Example 1, powder was obtained by the same operation and conditions as in Example 1, except that titanium oxide having an Si content of 9351 ppm (average particle diameter: 0.64 µm, BET specific surface area: 6.7 m 2 / g) was used. . The obtained powder was analyzed in the same manner as in Example 1. The result of the analysis was the same as in Example 1, and the obtained powder was confirmed to be Mg ₂ TiO ₄ : 0.4 mol% Mn ^{4 +} .

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

About the fluorescent substance 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 below.

<Evaluation of fluorescence characteristics>

For the phosphor samples obtained in Example 1 and Comparative Example 1, the maximum wavelength of the emission spectrum at the excitation wavelength 460 nm, the emission intensity at the maximum wavelength, and the CIE chromaticity were measured. The measurement results are shown in Table 1. In addition, the light emission intensity in the maximum wavelength was shown as the relative intensity value when the light emission intensity of the phosphor sample of Comparative Example 1 was 100. 1 shows the fluorescence spectrum of the phosphor sample obtained in Example 1. FIG.

The emission spectrum and CIE chromaticity were measured as follows.

Emission spectrum: The spectrum was obtained by making excitation light 460 nm using the fluorescence spectrophotometer (made by Hitachi High Technology), and scanning the range of 430-800 nm.

CIE chromaticity: The xy colorimetric chromaticity coordinates were calculated according to JIS Z 8701 from the relative fluorescence spectrum at an excitation wavelength of 460 nm.

EXAMPLE 2

Instead of the titanium oxide used in Example 1, a powder was obtained under the same operation and conditions as those in Example 1, except that titanium oxide having an Si content of 9.4 ppm (average particle diameter: 0.64 µm) was used. The obtained powder was analyzed in the same manner as in Example 1. The result of the analysis was the same as in Example 1, and the obtained powder was confirmed to be Mg ₂ TiO ₄ : 0.4 mol% Mn ^{4 +} . About the obtained powder, it carried out similarly to Example 1, and measured Si content, average particle diameter, and BET specific surface area, and evaluated fluorescence characteristic. The results are shown in Table 1.

From the description of Table 1, it is clear that the Si content affects the emission intensity of the red phosphor. If Si content is 24000 ppm or less, the improvement effect to light emission intensity will be recognized, and if it is 15000 ppm or less (Example 1), especially 100 ppm or less (Example 2), the very high improvement effect will be recognized.

Claims (11)

A red phosphor, which is formed by activating Mn on a titanate represented by the following formula (1) and having a Si content of 24000 ppm or less.
<Formula 1>

(Wherein M represents one or two or more alkaline earth metal elements) The red phosphor according to claim 1, which emits light by excitation light of 270 to 550 nm. The red phosphor according to claim 1 or 2, wherein the red phosphor has a light emitting band in a region of 600 to 750 nm. The red phosphor according to any one of claims 1 to 3, wherein M in Formula 1 is Mg. The red phosphor according to any one of claims 1 to 4, wherein the red phosphor has an average particle diameter of 1 to 30 µm. After mixing an alkaline earth metal source, a manganese source, and a titanium source, baking the obtained mixture to obtain a fired body, and then annealing the fired body,
As said each metal source, the quantity of Si contained in these uses what has purity of the quantity whose Si content of a red fluorescent substance obtained is 24000 ppm or less, The manufacturing method of the red fluorescent substance of Claim 1 characterized by the above-mentioned. The method for producing a red phosphor according to claim 6, wherein the Si content of the titanium source is 9000 ppm or less. The method for producing a red phosphor according to claim 6 or 7, wherein mixing of the alkaline earth metal source, the manganese source, and the titanium source is performed by a wet method. The manufacturing method of red fluorescent substance of any one of Claims 6-8 whose baking temperature is 1150-1600 degreeC. The manufacturing method of the red fluorescent substance in any one of Claims 6-9 whose temperature of annealing process is 500-800 degreeC. The method for producing a red phosphor according to any one of claims 6 to 10, wherein the titanium source is titanium dioxide.

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