WO2012050051A1

WO2012050051A1 - Method for producing manganese-activated germanate phosphor

Info

Publication number: WO2012050051A1
Application number: PCT/JP2011/073175
Authority: WO
Inventors: 淳良柳原
Original assignee: 日本化学工業株式会社
Priority date: 2010-10-13
Filing date: 2011-10-07
Publication date: 2012-04-19
Also published as: TW201229210A

Abstract

Provided is a method for producing a manganese-activated germanate phosphor that has a high emission intensity and is represented by general formula (1), a(Mg_1-xM1_x)O∙bMgF₂∙c{(Ge_1-yM2_y)O₂}:nMn⁴⁺ (1) the method for producing a manganese-activated germanate phosphor being characterized in that a mixed slurry is prepared by mixing a dispersant with magnesium fluoride, a magnesium compound other than magnesium fluoride, a germanium compound, a manganese compound, and one or more compounds containing additional elements selected from the above-mentioned M1 elements and M2 elements added as necessary, this starting mixed slurry is wet mixed using a media mill, the resulting uniformly mixed slurry is spray dried to obtain a reaction precursor, and this reaction precursor is fired.

Description

Method for producing manganese-activated germanate phosphor

The present invention relates to a method for producing a manganese-activated germanate phosphor useful as a red phosphor.

In recent years, blue diodes have been put into practical use, and many studies on white light emitting diodes using these diodes as light sources are well known. Light emitting diodes have the advantages of being light, do not use mercury, and have 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. However, strictly speaking, the light emitting diode is not white but becomes white mixed with green and blue. Therefore, 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 red phosphors that absorb blue light and emit red fluorescence, but there are few reports on inorganic materials.

On the other hand, as general red phosphors, inorganic materials such as oxide phosphors, oxysulfide phosphors, sulfide phosphors and nitride phosphors have been proposed, and manganese-activated germanate phosphors have also been proposed. Yes.
A general method for producing a manganese-activated germanate phosphor is obtained by mixing magnesium oxide, magnesium fluoride, germanium oxide and manganese carbonate with a ball mill or the like and firing the resulting mixture at 1000 to 1200 ° C. It is known.
For example, Patent Document 1 below proposes a method in which magnesium fluoride, magnesium oxide, germanium oxide, and manganese fluoride are mixed in a dry ball mill and fired.
Further, in Patent Document 2 below, magnesium oxide is used as a magnesium compound, and a container containing magnesium oxide, magnesium fluoride, gallium oxide and a manganese compound is moved regularly or irregularly, or by an external stirring means. There has been proposed a method of obtaining a manganese-activated germanic acid phosphor having large primary particles and not containing fine particle aggregates by firing the raw materials while stirring.
Conventionally, the manganese-activated germanic acid phosphor is often obtained by a method of mixing each raw material in a dry or wet manner and firing the resulting uniform mixture, and the phosphor thus obtained has a problem in emission intensity. Yes, the quantum yield was low.

JP 58-158387 A JP-A-11-158464

Problems to be solved by the invention

Therefore, the present invention provides a method for industrially advantageously producing a manganese-activated germanic acid phosphor whose performance is further improved over the conventional manganese-activated germanic acid phosphor.

The present invention relates to the following general formula (1)

(In the formula, M1 represents one or more elements selected from the group of Zn, Cu, Cd, Ca, Hg, Sr, Ba, and M2 represents one or more elements selected from the group of Si, Sn, Pb, or 2 or more elements are represented, a is 0 <a ≦ 4, b is 0.5 ≦ b ≦ 4, c is 0.8 ≦ c ≦ 1.2, n is 0.001 ≦ n ≦ 0.05, x represents 0 ≦ x ≦ 0.2 and y represents 0 ≦ y ≦ 0.28.) A method for producing a manganese-activated germanate phosphor represented by: A mixed slurry is prepared by mixing one or more of an additive element-containing compound containing an additive element selected from a magnesium compound, a germanium compound, a manganese compound, and the M1 element and the M2 element that are added as necessary, with a dispersion medium. This raw material mixed slurry is wet mixed by a media mill. And reaction precursor and without a uniform mixed slurry is subjected to spray drying to obtain, there is provided a manganese activated germanate salt phosphor and firing the reaction precursor.

According to the present invention, a manganese-activated germanate phosphor having high red light emission intensity can be obtained by an industrially advantageous method.

FIGS. 1A and 1B are SEM images of the reaction precursor obtained in Example 1. FIG. 1A is a magnification of 1000 times, and FIG. 1B is a magnification of 3000 times. 2 (a) and 2 (b) are SEM images of the manganese-activated germanate phosphor particles obtained in Example 1, FIG. 2 (a) is 1000 times and FIG. 2 (b) is 3000 times. Is double. 3 (a) and 3 (b) are SEM images of the manganese-activated germanate phosphor particles obtained in Comparative Example 1, FIG. 3 (a) is 1000 times, and FIG. 3 (b) is 3000 times. Is double.

Hereinafter, the present invention will be described based on preferred embodiments thereof.
The manganese-activated germanate phosphor obtained by this production method is basically excited by blue light and emits red light. Specifically, excitation is performed with excitation light of at least 270 to 550 nm, preferably 380 to 490 nm. Further, it has an emission band in a region of 580 to 750 nm, preferably 600 to 700 nm (that is, has a red spectrum).
The manganese-activated germanate phosphor obtained by this production method is represented by the following general formula (1).

In the general formula (1), M1 represents one or more elements selected from the group of Zn, Cu, Cd, Ca, Hg, Sr, Ba, and M2 is selected from the group of Si, Sn, Pb. 1 type or 2 or more types of elements are shown. The M1 element is an element that is partially substituted with a magnesium atom if necessary, and is contained in a manganese-activated germanate phosphor to further improve the emission height. The M2 element is also partially substituted with a germanium atom if necessary. It is an element that is incorporated in the manganese-activated germanate phosphor and further improves the light emission height.
In the formula (1), a is 0 <a ≦ 4, preferably 1 ≦ a ≦ 3.4, b is 0.5 ≦ b ≦ 4, preferably 0.6 ≦ b ≦ 3, and c is 0. .8 ≦ c ≦ 1.2, preferably 0.9 ≦ c ≦ 1.1, n is 0.001 ≦ n ≦ 0.05, preferably 0.005 ≦ n ≦ 0.03, x is 0 ≦ x ≦ 0.2, preferably 0 ≦ x ≦ 0.15, y is 0 ≦ y ≦ 0.28, preferably 0 ≦ y ≦ 0.25.

The method for producing a manganese-activated germanate phosphor having the above composition according to the present invention comprises magnesium fluoride, a magnesium compound other than magnesium fluoride, a germanium compound, a manganese compound, and the M1 element and the M2 element added as necessary. A mixed slurry is prepared by mixing one or more additive element-containing compounds (hereinafter sometimes simply referred to as “additive element-containing compounds”) containing the selected additive element with a dispersion medium. It includes a step of wet-mixing with a media mill and subjecting the resulting uniform mixed slurry to a spray drying method to form a reaction precursor and firing the reaction precursor. That is, this manufacturing method roughly includes (a) a uniform mixed slurry preparation step, (b) a spray drying step, and (c) a firing step.

In the step (b) of preparing the homogeneously mixed slurry, magnesium fluoride, a magnesium compound other than magnesium fluoride (hereinafter simply referred to as “magnesium compound”), a germanium compound, a manganese compound, and an additive element-containing compound added as necessary Are uniformly mixed in a dispersion medium to prepare a uniform mixed slurry in which the raw materials are uniformly mixed.

The preferable physical property of magnesium fluoride is that the average particle diameter is 10 μm or less, particularly 0.1 to 1 μm, from the viewpoint of easy uniform mixing.

As the magnesium compound, in addition to magnesium oxide, those that can be converted into magnesium oxide in the firing step described later (c) and those that are hardly soluble or insoluble in the dispersion medium described later are used. As such a magnesium compound, for example, magnesium oxide, carbonate, oxalate, sulfate, hydroxide and the like can be used. These compounds can use 1 type (s) or 2 or more types. Among these, magnesium hydroxide is preferably used in that impurities do not remain after firing and the reactivity between raw materials is high. A preferable physical property of the magnesium compound is that the average particle diameter is 5 μm or less, particularly 0.2 to 2 μm, from the viewpoint of easy uniform mixing.

As the germanium compound, those which are hardly soluble or insoluble in the dispersion medium described later are used. Examples of the germanium compound include germanium oxide, sulfate, nitrate, hydroxide, and organic acid salt. These compounds can use 1 type (s) or 2 or more types. Among these, germanium oxide is preferably used because it is low in volatility and hardly hydrolyzed. The preferred physical property of the germanium compound is that the average particle diameter is 50 μm or less, particularly 1 to 30 μm, from the viewpoint of easy uniform mixing.

As the manganese compound, for example, manganese oxide, hydroxide, carbonate, nitrate, sulfate, organic acid salt 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 it is easily dissolved in the base crystal. The manganese compound may be water-soluble or water-insoluble. When the manganese compound is water-insoluble, its average particle size is preferably 10 μm or less, particularly 1 to 9 μm, from the viewpoint of easy uniform mixing.

As the additive element-containing compound, those which are hardly soluble or insoluble in the dispersion medium described later are used. Examples of the additive element-containing compound include oxides, hydroxides, halides, carbonates, nitrates, and organic acid salts containing additive elements. These compounds can use 1 type (s) or 2 or more types. A preferable physical property of the additive element-containing compound is that the average particle diameter is 10 μm or less, particularly 1 to 9 μm, from the viewpoint of easy uniform mixing.

The production history of the above-described magnesium fluoride, magnesium compound, germanium compound, manganese compound, and additive element-containing compound added as necessary is not limited, but it is as much as possible to produce a high-purity manganese-activated germanate phosphor. It is preferable that the content of impurities is small.

In this production method, the mixing ratio of the magnesium fluoride, magnesium compound, germanium compound, manganese compound, and additive element-containing compound added as necessary is determined according to the composition of the desired manganese-activated germanate phosphor. What is necessary is just to select suitably the mixture ratio of these.
Specifically, when an additive element-containing compound is not added, the mixing ratio of magnesium fluoride, magnesium compound, germanium compound and manganese compound is such that the amount of magnesium fluoride added is in the germanium atom and manganese compound in the germanium compound. The molar ratio of the number of magnesium fluoride molecules to the total number of manganese atoms (MgF ₂ / (Ge + Mn)) is 0.5 to 4, preferably 0.6 to 3. Further, the addition amount of the magnesium compound is larger than 0 by a molar ratio (Mg / (Ge + Mn)) of the number of magnesium atoms in the magnesium compound to the total number of germanium atoms in the germanium compound and manganese atoms in the manganese compound. Hereinafter, it is preferably 1 to 3.4. The added amount of the manganese compound is 0.001 to 0.00 in terms of a molar ratio of the number of manganese atoms in the manganese compound to the total number of germanium atoms in the germanium compound and manganese atoms in the manganese compound (Mn / (Ge + Mn)). 05, preferably 0.005 to 0.03.
When adding an M1 element-containing compound containing an M1 element, the molar ratio of the number of M1 atoms in the M1 element-containing compound to the total number of magnesium atoms in the magnesium compound and the M1 atom in the M1 element-containing compound ( M1 / Mg + M1) is greater than 0 and less than or equal to 0.2, preferably greater than 0 and less than or equal to 0.15, and when an M2 element-containing compound containing M2 element is added, the germanium atom in the germanium compound and the M2 element-containing compound The molar ratio of the number of M2 atoms in the M2 element-containing compound to the total number of M2 atoms (M2 / Ge + M2) is preferably greater than 0 and less than or equal to 0.28, preferably greater than 0 and less than or equal to 0.25.

Magnesium fluoride, a magnesium compound, a germanium compound, a manganese compound, and an additive element-containing compound added as necessary are mixed with a dispersion medium to form a mixed solution. As the dispersion medium, it is preferable to use water or an aqueous solution in which a water-soluble organic solvent is mixed with water. The solid content concentration in the mixed solution is preferably 5 to 40% by weight, more preferably 10 to 30% by weight, from the viewpoint of efficient mixing using a media mill.

As a mixing method for preparing a uniformly mixed slurry, in this manufacturing method, processing using a media mill, which is a device that can simultaneously perform pulverization and mixing, is performed. By adopting this method, a uniform mixed slurry in which the raw materials are uniformly mixed can be obtained more easily.

As the media mill, a bead mill, a ball mill, a paint shaker, an attritor, a sand mill, or the like can be used. It is particularly preferable to use a bead mill. In that case, the operating conditions and the type and size of the beads may be appropriately selected according to the size and processing amount of the apparatus and the type of raw material to be used.

From the viewpoint of more efficiently performing the treatment using the media mill, a dispersant may be added to the mixed slurry. What is necessary is just to select a suitable dispersing agent to use according to the kind of dispersion medium. When the dispersion medium is water, for example, various surfactants, polycarboxylic acid ammonium salts, and the like can be used as the dispersant. The concentration of the dispersant in the mixed slurry is preferably 0.01 to 10% by weight, particularly 0.1 to 5% by weight from the viewpoint of obtaining a sufficient dispersion effect.

The mixing treatment using the media mill is carried out until the average particle size of the solid content is 5 μm or less, preferably 1 μm or less, particularly preferably 0.1 to 0.5 μm, to obtain a single target composition. Therefore, it is preferable from the viewpoint of obtaining a product with high luminous efficiency. This average particle diameter can be measured by a light scattering particle size distribution measuring apparatus.

The homogeneously mixed slurry thus obtained is subjected to the spray drying step (b) to obtain a reaction precursor. Although methods other than the spray drying method are known as the drying method of the mixed liquid, this drying method is adopted based on the knowledge that it is advantageous to select the spray drying method in this production method. . Specifically, since a reaction precursor having a true sphere or a shape close thereto can be obtained by using a spray drying method, spherical manganese-activated germanate phosphor particles can be easily obtained. Further, when the spray drying method is used, a reaction precursor can be obtained in a state where solid material particles are densely packed, so that a single target composition can be obtained in the firing step (c).

In the spray drying method, a reaction precursor is obtained by atomizing the mixed solution by a predetermined means and drying fine droplets generated thereby. There are, for example, a method using a rotating disk and a method using a pressure nozzle for atomization of the mixed liquid. Any method can be used in this step.

In the spray drying method, the drying temperature when drying the mixed solution is preferably 100 to 250 ° C., particularly preferably 150 to 250 ° C. from the viewpoint of stably obtaining a sufficiently dried powder.

In the spray drying method, the relationship between the size of the droplets of the atomized mixed liquid and the size of the raw material particles contained therein affects stable drying and the properties of the resulting reaction precursor. . Specifically, if the size of the solid material particles is too small with respect to the size of the droplets, the droplets become unstable, making it difficult to dry successfully. From this point of view, the size of the atomized droplets is 5 to 150 μm, particularly 10 to 120 μm, provided that the size of the raw material particles in the mixed solution is in the above-mentioned range. preferable. It is desirable to determine the supply amount of the mixed liquid to the spray dryer in consideration of this viewpoint.

The spray drying method is carried out so that the average particle size of the reaction precursor is 1 to 50 μm, preferably 1 to 30 μm, particularly preferably 10 to 30 μm. This is preferable from the viewpoint of controlling the particle size. This average particle diameter is measured using, for example, a light scattering particle size distribution measuring apparatus.

The spherical reaction precursor thus obtained is subjected to the firing step (c) to obtain a manganese-activated germanate phosphor. In this production method, the reaction precursor obtained by subjecting it to a spray drying step is preferably calcined at 1000 ° C. or higher. The upper limit temperature of the firing temperature is 1250 ° C. because dissolution starts and the particle shape cannot be maintained. In addition, when firing is performed at 1050 to 1200 ° C., a single target composition can be obtained while maintaining the particle shape, the particle surface can be smoothed, and a product with high luminous efficiency can be obtained. It is particularly preferable from the viewpoint of being produced.

The firing time is not critical in this production method. In general, a satisfactory manganese-activated germanate phosphor can be obtained by firing for 3 hours or more, particularly 5 to 36 hours.
The firing atmosphere is not critical in the present production method, and may be any of an oxidizing gas atmosphere such as air and an inert gas atmosphere.

The fired body obtained in this way may be subjected to a plurality of firing steps as necessary.
After firing, the resulting manganese-activated germanate phosphor may be crushed or crushed as necessary, and further classified.

Thus, a manganese-activated germanate phosphor is obtained as a single composition. The preferred physical property of the manganese-activated germanate phosphor is an average particle size determined by a light scattering particle size distribution analyzer of 5 to 35 μm. The thickness is preferably 10 to 30 μm. When the average particle diameter is in the above range, excitation light can be absorbed more efficiently. The average particle diameter is measured by a laser diffraction / scattering particle size distribution analyzer (LA-920) manufactured by Horiba. The BET specific surface area is 0.1 to 1 m ² / g, preferably 0.2 to 0.7 m ² / g. When the BET specific surface area is in the above range, absorption of excitation light becomes sufficient, and scattering of excitation light can also be prevented, so that the emission intensity can be sufficiently increased.

In addition, the manganese-activated germanate phosphor obtained by the present production method has a spherical particle shape. In addition, as long as the particle shape is a shape that can be regarded as a sphere, it is not necessarily a true sphere. In general, the degree of sphericity can be expressed by sphericity. Manganese-activated germanate phosphors have a sphericity of about 1.0 to 1.8, particularly about 1.0 to 1.7. Just do it. The spherical manganese-activated germane salt phosphor has a higher quantum yield and higher emission intensity than other shaped particles. The sphericity is defined by the area of the perfect circle formed by the maximum diameter of the projected figure / the actual area of the projected figure when the particles are projected two-dimensionally. Therefore, the closer the sphericity value is to 1, the closer the particle is to a true sphere.
Moreover, it is preferable that the particle | grain surface of the manganese activation germanate fluorescent substance obtained by this manufacturing method is smooth. The degree of smoothness of the surface of the particles of the manganese-activated germanate phosphor can be expressed by, for example, the degree of unevenness. It only needs to have a smoothness of about 0 to 1.5. The degree of unevenness is defined as the area of a perfect circle calculated from the perimeter of the projected figure / the actual area of the projected figure when the particles are projected two-dimensionally. Therefore, the closer the roughness value is to 1, the smoother the surface of the particles.

The sphericity and unevenness can be measured using, for example, an image analyzer. An example of such an apparatus is LUZEX AP manufactured by Nicole. The measurement is performed on 300 particles arbitrarily extracted. The magnification of the particles is 400 to 300,000 times depending on the size.

The manganese-activated germanate phosphor of the present invention can be further surface treated with a metal oxide for the purpose of improving moisture resistance.
Examples of the metal oxide include Be, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Sr, Y, Zr, and Nb. , Mo, Cd, In, Sn, Sb, Te, Ba, La, Hf, Ta, W, Tl, Pb, Bi, Ce, Pr, Nb, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er One or more metal oxides selected from Tm, Yb, Lu, Th, Pa, U, and Pu are used.
As a method for coating the surface of the manganese-activated germanate phosphor particles with these metal oxides, a known method can be used. For example, a metal alkoxide containing the metal element is used. Then, the metal alkoxide is added to a slurry or suspension containing the manganese-activated germanate phosphor particles, and a hydrolysis reaction of the metal alkoxide is performed in the presence of an acid catalyst or an alkali catalyst, if necessary. Examples thereof include a method of uniformly treating the surface of the germanate phosphor particles with the metal oxide.

The manganese-activated germanate phosphor thus obtained can be suitably used as a red phosphor, and the red phosphor is, for example, a display device such as an electrolytic emission display, a plasma display, or an electroluminescence. It can be used for various light emitting device applications such as. Moreover, since it has an excitation spectrum close to around 450 nm, it can be applied to a blue LED excitation phosphor. It is particularly suitable for use in electroluminescent display devices. Also, by a method using in combination with a blue excited green phosphor, a method using a blue LDE element and a blue excited green phosphor in combination, or a method using a blue LDE element and a blue excited yellow light emitting phosphor in combination, etc. It can also be applied to white LEDs.

Hereinafter, the present invention will be described with reference to examples. However, the scope of the present invention is not limited to these examples. Unless otherwise specified, “%” means “% by weight”.
[Example 1]
(I) Uniform slurry preparation step; magnesium hydroxide (average particle size 0.57 μm), magnesium fluoride (average particle size 19.0 μm), germanium oxide (average particle size 17.7 μm) and manganese carbonate (average particle size 5) 2 μm), the molar ratio of Mg: Ge: F: Mn is 4: 0.99: 2.0: 0.01, that is, Mn / (Ge + Mn) = 0.01, MgF ₂ / (Ge + Mn) = 1. It was weighed so that 0, Mg / (Ge + Mn) = 4.0, and charged in a ball mill. Water and a dispersant (manufactured by Kao Corporation, Poise 2100) were added to the ball mill to prepare a mixed solution having a solid content concentration of 15%. The concentration of the dispersant was 2%.
A bead mill was charged with zirconia balls having a diameter of 0.5 mm and mixed and ground by a wet method for 2 hours. When the average particle size of the solid content of the slurry after mixing and pulverization was measured by a light scattering method, it was 0.3 μm.
(B) Spray drying step (drying step); Then, the mixed solution was supplied at a supply rate of 45 ml / min to a spray dryer whose inlet temperature was set to 200 ° C. to obtain a reaction precursor. The average particle size of the reaction precursor was 22.8 μm. An electron micrograph (SEM image) of the reaction precursor is shown in FIGS.
(C) Firing step: This reaction precursor was charged into an electric furnace and baked in a stationary state at 1150 ° C. for 6 hours in the atmosphere.
In this way, 3MgO _· MgF ₂ _· 0.99GeO ₂ aims: to obtain a manganese-activated germanate salt is 0.01Mn ^4+. When X-ray diffraction measurement was performed on the obtained manganese-activated germanate phosphor, the manganese-activated germanate phosphor was composed of Mg ₁₄ Ge ₅ O ₂₄ and MgO, and the manganese activation of a single composition It was confirmed to be a germanate phosphor. The SEM image of this manganese activation germanate fluorescent substance is shown to Fig.2 (a) and (b).

[Example 2]
3MgO · MgF ₂ · 0.995GeO ₂ : 0.00 in the same manner as in Example 1 except that in the preparation step (a) of the uniform mixed slurry of Example 1, the charged molar ratio was Mn / (Ge + Mn) = 0.005. A manganese-activated germanate phosphor of 005Mn ⁴⁺ was obtained. When X-ray diffraction measurement was performed on the obtained manganese-activated germanate phosphor, it was composed of Mg ₁₄ Ge ₅ O ₂₄ and MgO, and was a single-composition manganese-activated germanate phosphor. confirmed.

Example 3
3MgO · MgF ₂ · 0.97GeO ₂ : 0.00 in the same manner as in Example 1 except that, in the step (b) of preparing the uniform mixed slurry of Example 1, the charged molar ratio was Mn / (Ge + Mn) = 0.03. A manganese-activated germanate phosphor of 03Mn ⁴⁺ was obtained. When X-ray diffraction measurement was performed on the obtained manganese-activated germanate phosphor, it was composed of Mg ₁₄ Ge ₅ O ₂₄ and MgO, and was a single-composition manganese-activated germanate phosphor. confirmed.

Example 4
In the step (a) of preparing the homogeneously mixed slurry of Example 1, 3.4 MgO · 0.6MgF ₂ .0 .0 was performed in the same manner as in Example 1 except that the charged molar ratio was MgF ₂ /(Ge+Mn)=0.6. A manganese-activated germanate phosphor of 99GeO ₂ : 0.01Mn ⁴⁺ was obtained. When X-ray diffraction measurement was performed on the obtained manganese-activated germanate phosphor, it was composed of Mg ₁₄ Ge ₅ O ₂₄ and MgO, and was a single-composition manganese-activated germanate phosphor. confirmed.

Example 5
MgO · 3MgF ₂ · 0.99GeO ₂ : 0 in the same manner as in Example 1 except that in the (a) uniform mixed slurry preparation step of Example 1, the charged molar ratio was MgF ₂ /(Ge+Mn)=3.0. A manganese-activated germanate phosphor of .01Mn ⁴⁺ was obtained. When X-ray diffraction measurement was performed on the obtained manganese-activated germanate phosphor, it was composed of Mg ₁₄ Ge ₅ O ₂₄ and MgO, and was a single-composition manganese-activated germanate phosphor. confirmed.

Example 6
2MgO · MgF ₂ · 0.99GeO ₂ : 0.00 in the same manner as in Example 1 except that in the preparation step (a) of the homogeneously mixed slurry of Example 1, the charged molar ratio was Mg / (Ge + Mn) = 3.0. A manganese-activated germanate phosphor of 01Mn ⁴⁺ was obtained. When X-ray diffraction measurement was performed on the obtained manganese-activated germanate phosphor, it was composed of Mg ₁₄ Ge ₅ O ₂₄ and MgO, and was a single-composition manganese-activated germanate phosphor. confirmed.

Example 7
The manganese-activated germanate phosphor of 3MgO · MgF ₂ · 0.99GeO ₂ : 0.01Mn ⁴⁺ in the same manner as in Example 1 except that the firing temperature is 1075 ° C. in the firing step (c) of Example 1. Got. When X-ray diffraction measurement was performed on the obtained manganese-activated germanate phosphor, it was composed of Mg ₁₄ Ge ₅ O ₂₄ and MgO, and was a single-composition manganese-activated germanate phosphor. confirmed.

[Comparative Example 1]
In the (b) spray drying step (drying step) of Example 1, 3MgO · MgF ₂ was performed in the same manner as in Example 1 except that the wet pulverized slurry was left to stand and dried instead of obtaining spherical particles using a spray dryer. · 0.99GeO _2: to obtain a manganese-activated germane salt phosphor is 0.01Mn ^4+. When X-ray diffraction measurement was performed on the obtained manganese-activated germanate phosphor, it was composed of Mg ₁₄ Ge ₅ O ₂₄ and MgO, and was a single-composition manganese-activated germanate phosphor. confirmed. SEM images of this manganese-activated germanate phosphor are shown in FIGS. 3 (a) and 3 (b).

[Supplement under rule 26 24.10.2011]

〔Evaluation of the physical properties〕
The average particle diameter, sphericity, unevenness, and BET specific surface area of the manganese-activated germanate phosphors obtained in the examples and comparative examples were measured by the methods described above. In addition, the surface of the manganese-activated germanate phosphor particles was observed in 3000 times SEM observation. The results are shown in Table 2.

[Evaluation]
About the manganese activation germanate fluorescent substance obtained by the Example and the comparative example, the internal quantum efficiency and the relative light emission intensity in excitation wavelength 450nm were measured with the following method. The results are shown in Table 3 below.

[Internal quantum efficiency]
Using a fluorescence spectrophotometer (F-7000) manufactured by Hitachi High-Tech, Inc. and an attached integrating sphere, the excitation light was 450 nm, and the conversion efficiency was obtained by scanning the range from 420 to 700 nm. An aluminum oxide powder was used as a sample for measuring the total scattered light. The spectral intensity integrated value of 435 to 475 nm obtained by aluminum oxide is used as the excitation light amount, and the spectral intensity integrated value of 435 to 475 nm obtained by the phosphor sample is used as the excitation light amount after absorption, and from 600 obtained by the phosphor sample. The integral value of spectral intensity at 700 nm was determined as the amount of fluorescence. And the internal quantum efficiency was calculated | required from the following formula | equation.
Internal quantum efficiency (%) = 100 x fluorescence amount / (excitation light amount-excitation light amount after absorption)

[Relative emission intensity]
Using a fluorescence spectrophotometer (F-7000) manufactured by Hitachi High-Tech Co., Ltd., excitation light was set to 450 nm, and a range from 470 to 800 nm was scanned to obtain a fluorescence spectrum. The relative light emission intensity was determined from the obtained intensity value with the maximum light emission intensity being 100.

As is clear from the comparison with FIGS. 2 and 3, the manganese-activated germanate phosphor of the first example (the product of the present invention) was agglomerated of primary particles compared to the manganese-activated germanate phosphor of the first comparative example. It can be seen that a spherical shape is formed. The germanate phosphor of Comparative Example 1 has an irregular shape.
Further, as apparent from the results shown in Table 3, the manganese-activated germanate phosphor of the first example (product of the present invention) emits light in the red region as compared with the manganese-activated germanate phosphor of the first comparative example. It can be seen that the strength is high.

Claims

The following general formula (1)

(In the formula, M1 represents one or more elements selected from the group of Zn, Cu, Cd, Ca, Hg, Sr, Ba, and M2 represents one or more elements selected from the group of Si, Sn, Pb, or 2 or more elements are represented, a is 0 <a ≦ 4, b is 0.5 ≦ b ≦ 4, c is 0.8 ≦ c ≦ 1.2, n is 0.001 ≦ n ≦ 0.05, x represents 0 ≦ x ≦ 0.2 and y represents 0 ≦ y ≦ 0.28.) The method for producing a manganese-activated germanate phosphor represented by:
Magnesium fluoride, magnesium compound other than magnesium fluoride, germanium compound, manganese compound, and one or more of additive element-containing compounds containing an additive element selected from the M1 element and the M2 element added as necessary Prepare a mixed slurry mixed with the dispersion medium, wet mix this raw material mixed slurry with a media mill, subject the resulting uniform mixed slurry to a spray drying method to make a reaction precursor, and calcine this reaction precursor A method for producing a manganese-activated germanate phosphor characterized by comprising:
2. The method for producing a manganese-activated germanate phosphor according to claim 1, wherein spray drying is performed so that the average particle size of the reaction precursor is 1 to 50 μm.
The method for producing a manganese-activated germanate phosphor according to claim 1 or 2, wherein the average particle size of the solid content of the uniformly mixed slurry is 5 µm or less.
The method for producing a manganese-activated germanate phosphor according to any one of claims 1 to 3, wherein the firing temperature is 1000 ° C or higher.