JP2000297280A - Trivalent rare earth ion-containing aluminate fluorescent substance, its production and emission device using the fluorescent substance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a trivalent rare earth ion-containing aluminate fluorescent substance of particle shapes and particle sizes originated from the fluorescent substance raw material and having high light emission performance. SOLUTION: A fluorescent substance raw material containing an aluminum- containing granular material is heated at a specific temperature (e.g. 1,500-1,800 deg.C) in an oxidizing atmosphere to obtain an intermediate fluorescent substance. After disintegration, the intermediate fluorescent substance is heated at a specific temperature (e.g. 1,400-1,800 deg.C) in a reducing atmosphere in a production process for a trivalent rare earth ion-containing aluminate fluorescent substance. Here, the heating temperature in the reducing atmosphere is equal to or lower than the heating temperature in the oxidizing atmosphere.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a trivalent rare earth ion-containing aluminate phosphor suitable as a phosphor for a light-emitting device (light-emitting device) such as a fluorescent lamp and a method for producing the same. Further, the present invention relates to a light emitting device using the phosphor.

[0002]

2. Description of the Related Art Conventionally, as a trivalent rare earth ion-containing aluminate phosphor for a light emitting device such as a fluorescent lamp, CeMgAl ₁₁ O ₁₉ : Tb ³⁺ , Ce (III) MgA has been used.
l ₁₁ O ₁₉ , Ce (III) MgAl ₁₁ O ₁₉ : Mn ²⁺ , Ce
Aluminate phosphors such as MgAl ₁₁ O ₁₉ : Tb ³⁺ , Mn ²⁺ , Y ₃ Al ₅ O ₁₂ : Tb ³⁺ , Y ₃ Al ₅ O ₁₂ : Ce ³⁺
A phosphor mainly composed of a compound represented by the following chemical formula is known.

[0003] As a method for producing these trivalent rare earth ion-containing aluminate phosphors, a phosphor raw material to which a reaction accelerator (also called flux; for example, a halide such as aluminum fluoride or a boride such as boric acid) is added is used. Heating using a furnace or the like (for example, Phosphor Handbook 2
27, JP-A-49-77893), a method of heating a phosphor raw material without adding a reaction accelerator (for example,
JP-A-151372, JP-A-10-88127), a method of heating a phosphor raw material containing a particulate α-alumina powder having substantially no crushed surface (for example, JP-A-10-53760, Japanese Unexamined Patent Publication No. 10-273656), an aqueous solution obtained by mixing a raw material compound that can be a raw material of a phosphor is dropped as a droplet in a solution cooled below the freezing point to produce a frozen body of the phosphor raw material solution. Heating a particulate phosphor material obtained by vacuum drying (for example, JP-A-9-291275), a method of spray pyrolysis of a colloid solution containing an aluminum compound and a metal nitrate, A method of heating the phosphor material (for example, Proceedings of 3rd International Confere
nce on the Science and Technology of Display Phosp
hors, p.257 (1997)), a rare earth ion and an oxalate ion are reacted in the presence of an organic base, and the precipitated rare earth oxalate is separated by filtration, washed with water, and then placed in steam-unsaturated air, vacuum dried or frozen. A method of heating a phosphor raw material containing a particulate rare earth compound (center particle size: about 1 to 6 μm) having a spherical particle shape and a uniform particle size distribution obtained by vacuum drying (for example, Japanese Patent Application Laid-Open No. No. 88127).

According to the method of heating the phosphor material containing the particulate α-alumina powder, the uniform particle size is obtained by using a spherical or pseudo-spherical α-alumina powder having a uniform particle size. Thus, a spherical or pseudospherical trivalent rare earth ion-containing aluminate phosphor can be produced. Further, according to the method of heating a particulate phosphor material, which can be obtained by vacuum-drying the frozen material of the phosphor material solution or spray pyrolyzing a colloid solution, a spherical particle having a uniform particle size is obtained. It has been known that a spherical or pseudospherical trivalent rare earth ion-containing aluminate phosphor having a uniform particle size can be produced by using the phosphor raw material of (1).

In the production method in which the phosphor raw material to which the reaction accelerator is not added is heated, the particle shape of α-alumina used as the phosphor raw material and the particle shape of the synthesized trivalent rare earth ion-containing aluminate phosphor substantially match. (Japanese Patent Laid-Open No. 9-151372). In addition, by using a spherical α-alumina powder having a more uniform particle diameter than in the past as a part of the phosphor raw material and using the same, it is possible to synthesize a spherical trivalent rare earth ion-containing aluminate phosphor having a uniform particle diameter. Have also been reported.

Further, according to the manufacturing method of heating a phosphor material containing α-alumina powder having no crushed surface, a trivalent rare earth ion-containing aluminate having substantially the same particle shape as that of α-alumina powder It is known that not only a phosphor can be obtained, but also that the product yield can be kept high (for example, JP-A-10-53760 and JP-A-10-273656).

Further, the above-mentioned particulate phosphor raw material (eg, a particulate phosphor raw material obtained by vacuum-drying a frozen body of a phosphor raw material solution or by spray pyrolysis of a colloid solution) is heated. The method discloses that a trivalent rare earth ion-containing aluminate phosphor having substantially the same shape as the shape of the particulate phosphor material can be produced (for example, JP-A-9-291275).

[0008] JP-A-9-151372 and JP-A-10-151
The spherical aluminate phosphors having a uniform particle size as described in JP-A-53760, JP-A-10-273656, and JP-A-9-291275 have non-uniform specific surface areas. Approximately half that of a conventional phosphor (Preliminary lectures of the 270th Annual Meeting of the Society of Phosphors, pp. 1-8, 1998)
February 17). When the aluminate phosphor having such a uniform particle size is used, the heat deterioration characteristic of the phosphor is improved, and the total luminous flux of the fluorescent lamp is improved. Further, the ion bombardment of the fluorescent material during the lighting of the fluorescent lamp is reduced, and the time change of the emission color during the lighting of the lamp can be suppressed. These effects are also reported by the present inventors (IEEJ Technical Meeting, Optical Application and Vision Research Society, LAV-98-10, 19).
-25, November 25, 1998).

Due to these advantageous effects, aluminate phosphors having a uniform particle size (preferably spherical phosphors) are gaining particular attention as phosphors for small-tube type fluorescent lamps.

The aluminate phosphor having a uniform particle diameter and a spherical shape has an effect of increasing the transmission luminance of the phosphor film or increasing the reflection luminance of the phosphor film by using the phosphor in combination with the reflection film (Pr).
oceedings of the 4th Int.Display Workshops Novemb
er 19-21 1997, Nagoya, pp. 621-624) have also been confirmed by the present inventors.

[0011] From these effective effects, aluminate phosphors (preferably spherical phosphors) having a uniform particle size can be used for light-emitting devices (fluorescent lamps, plasma displays, CRTs).
(Cathod Ray-Tube), FED (Field Emission Displa)
y) etc.) are also promising as phosphors that can increase the emission intensity.

Hereinafter, a brief description will be given of a conventionally known method for producing a trivalent rare earth ion-containing aluminate phosphor.

The aluminate phosphor containing trivalent rare earth ions is basically produced by heating a phosphor material and causing the phosphor materials to react with each other. The phosphor raw material is prepared by mixing a plurality of compound raw materials containing phosphor constituent elements with a mixer such as a ball mill. In addition, the phosphor raw material is prepared by dropping an aqueous solution obtained by mixing the raw materials into a solution cooled below the freezing point to form a frozen body of the phosphor raw material solution, and then drying the frozen body in a vacuum or spray pyrolysis of the colloid solution. Can also be prepared. Alternatively, a precipitate obtained by dissolving a plurality of nitrates containing the constituent elements of a phosphor in water and then adding ammonium hydroxide thereto can be prepared by evaporating to dryness.

Usually, a halide such as aluminum fluoride or a boron compound such as boric acid is appropriately added to the phosphor raw material as a reaction accelerator. However, it is possible to synthesize a trivalent rare earth ion-containing aluminate phosphor without adding a reaction accelerator.

Heating (firing) of the phosphor material is performed in the air or in a reducing atmosphere (for example, in a mixed gas atmosphere of nitrogen and hydrogen). The firing may be repeated several times (for example, Phosphor Handbook, Ohmsha, pages 207 to 240). After heating in the air, firing may be performed in a reducing atmosphere. In this case, usually, firing is performed at a low temperature of 800 to 1500 ° C. in the atmosphere (temporary firing), and after the preliminary firing, firing is performed at a temperature of 1200 to 1800 ° C. higher than that in the air in a reducing atmosphere ( Main firing).

[0016]

As described above,
JP-A-9-151372, JP-A-10-53760
, JP-A-10-273656 and JP-A-9-2
91275 publications and Proceedings of 3rd Internati
onal Conference on the Science and Technologyof Di
splay Phosphors, p. 257 (1997), describes a production method capable of providing a phosphor (a phosphor having a uniform particle size and preferably a spherical shape) for improving the performance of a light emitting device.

However, in such a manufacturing method,
For the trivalent rare earth ion-containing aluminate phosphor,
There has been a problem that it is not possible to obtain a phosphor having both a desirable particle shape and high luminous performance derived from α-alumina powder which is a part of the phosphor raw material or a particulate phosphor raw material containing aluminum.

Hereinafter, this point will be described in detail. As described in each of the above publications, the phosphor raw material is calcined as it is or after calcining in an atmosphere of 1500 ° C. or less, and then calcined in a reducing atmosphere at a temperature of 1200 to 1800 ° C. higher than the calcining temperature for several hours. In the case of producing a trivalent rare earth ion-containing aluminate phosphor by reacting phosphor raw materials with each other, the higher the firing temperature in the reducing atmosphere, the higher the brightness. However, when the firing temperature is increased, the particle shape tends to be irregular, and the particle shape of α-alumina powder or the like cannot be maintained. For this reason, while keeping the particle shape of the phosphor in a preferable form,
It was difficult to achieve high luminance.

In order to explain this point more specifically,
FIG. 5 shows the relationship between the firing temperature and the luminance of the CeMgAl ₁₁ O ₁₉ : Tb ³⁺ trivalent rare earth ion-containing aluminate phosphor produced by the method described in JP-A-10-273656. FIG. 5 shows the luminance of CeMgAl ₁₁ O ₁₉ : Tb ³⁺ green phosphor (hereinafter also referred to as “commercial phosphor”) produced by the method using the reaction accelerator as 1
A relative luminance of 00 is shown.

As shown in FIG. 5, an attempt was made to produce a trivalent rare earth ion-containing aluminate phosphor having a luminance almost equivalent to a phosphor produced using a reaction accelerator without using a reaction accelerator. Then, it is necessary to set the firing temperature to 1700 ° C. or higher. However, C fired at such a high temperature
The particle shape of the eMgAl ₁₁ O ₁₉ : Tb ³⁺ green phosphor is such that even if spherical α-alumina powder having a uniform particle size is used as a part of the phosphor raw material, the particle shape of the phosphor is uneven and irregular. Becomes

That is, a spherical α-alumina powder having a uniform particle size as shown in FIG. 6A (for example, trade name: Advanced Alumina, Sumitomo Chemical Co., Ltd.) is used as an aluminum supply source, and the reaction is promoted. Even if it is manufactured without adding an agent, the manufactured CeMgAl ₁₁ O ₁₉ : Tb ³⁺
The aluminate phosphor containing trivalent rare earth ions does not reflect the shape of the α-alumina powder, and becomes amorphous (FIG. 6).
(C)).

As shown in FIG. 6D, the firing temperature is set to 1
At 600 ° C., a CeMgAl ₁₁ O ₁₉ : Tb ³⁺ green phosphor reflecting the shape of the α-alumina powder can be obtained. However, at this temperature, as shown in FIG. 5, the brightness level is less than 80% of the commercially available phosphor.

Such a problem is caused by BaMgAl ₁₀ O ₁₇ :
It has been reported that this does not occur in the case of producing a divalent rare earth ion-containing aluminate phosphor represented by the chemical formula of Eu ^2+. -8 pages). The above problem is a phenomenon peculiar to the trivalent rare earth ion-containing aluminate phosphor.

Further, in the method of heating the phosphor raw material obtained by vacuum-drying the frozen substance of the phosphor raw material solution or spray pyrolyzing the colloid solution, the method described above at a high temperature may be used. Calcined CeMgAl ₁₁ O ₁₉ : Tb ³⁺
There is a problem that the particle shape of the green phosphor is non-uniform and irregular.

In view of such circumstances, the present invention provides a method for producing a trivalent rare earth ion-containing aluminate phosphor having a particle shape and a particle diameter derived from a phosphor raw material and having high light emission performance. The purpose is to do. Another object of the present invention is to provide a trivalent rare earth ion-containing aluminate phosphor having a controlled shape and particle size by applying this manufacturing method.

[0026]

In order to achieve the above object, one embodiment of the method for producing a trivalent rare earth ion-containing aluminate phosphor according to the present invention is to oxidize a phosphor raw material containing a granular material containing aluminum. A step of heating the intermediate phosphor at a predetermined temperature in an atmosphere to produce the intermediate phosphor; and a step of heating the intermediate phosphor at a temperature lower than the predetermined temperature in a reducing atmosphere.

According to the above-mentioned production method, it is possible to produce a trivalent rare earth ion-containing aluminate phosphor having a particle shape and a particle diameter derived from the granular material contained in the phosphor material and having improved light emission performance. Can be. The predetermined temperature is preferably selected from a range from 1500 ° C. to 1900 ° C., as described later.

In the present specification, trivalent rare earth ions (Sc, Y, La, Ce, Pr, Nd, Pm, Sm, E
u, Gd, Tb, Dy, Ho, Er, Tm, Yb, L
The phosphor containing u), aluminum and oxygen is defined as a trivalent rare earth ion-containing aluminate phosphor. The phosphor includes, for example, an oxynitride phosphor such as CeAl ₁₂ O ₁₈ N: Tb ³⁺ . Further, the present invention provides a method for producing SrAl ₂ O ₄ : Eu ²⁺ , Dy ³⁺ , CaAl, which is not as effective as the above-described phosphor in which rare earth ions are contained as trivalent ions.
It is also effective for a phosphor in which a trivalent rare earth ion is added as a co-activator to a divalent europium activated phosphor, such as ₂ O ₄ : Eu ²⁺ and Nd ³⁺ . Here, the trivalent rare earth ion-containing aluminate phosphor also includes a phosphor containing trivalent rare earth ions as a coactivator.

In the production method of the present invention, it is not necessary that all of the phosphor raw materials be supplied as granules.
Granules containing aluminum are used as part of the phosphor raw material. The granular material may be supplied, for example, as a particulate aluminum-containing compound together with another raw material that supplies another element such as a rare earth element. Further, as the above-mentioned granular material, a particulate phosphor raw material prepared by previously vacuum-drying a frozen substance of a phosphor raw material solution or spray pyrolyzing a colloid solution may be used. In this case, it is preferable that the particulate phosphor material also contain an element such as a rare earth element.

In the production method of the present invention, the phosphor raw material preferably does not contain a reaction accelerator. Here, specific examples of the reaction accelerator include various halides and various boron compounds.

In the production method of the present invention, the particulate aluminum-containing compound is preferably α-alumina powder, and more preferably the α-alumina powder has substantially no crushed surface. Here, "having no crushing surface" means that there is no surface generated by crushing due to external stress applied through a process such as crushing, and preferably, each particle ( (For example, a polyhedron) is a crystal growth surface.

In the production method of the present invention, the trivalent rare earth ion
Containing aluminate phosphor is (Ce) _1-xL_x) (Mg_1-y
Mn_y) Al₁₁O₁₉The compound represented by
L is selected from elements belonging to Sc, Y and lanthanoids.
At least one element, x and y, respectively
0 ≦ x <1 and 0 ≦ y <1)
Is preferred. As a lanthanoid,
Is preferably La, Pr, Gd, Eu, Dy and Tb
And Tb is particularly preferred.

In the production method of the present invention, it is preferable that the intermediate phosphor is composed of particles having substantially the same particle shape as the granular material contained in the phosphor material. Here, the expression “the particle shape is the same” means that the shape is the same, and includes the so-called similarity.

In the production method of the present invention, the intermediate phosphor is a group of particles having a median particle diameter of not less than twice the median particle diameter of the granular material contained in the phosphor material and less than twice the median particle diameter. Is preferred. Here, the median particle size (median particle size) is defined as the cumulative number of particles counted according to the particle size distribution for a group of particles having a predetermined particle size distribution.
It means the particle size at the time when it becomes 0%.

In the production method of the present invention, specifically, the intermediate phosphor preferably comprises a group of particles having a median particle diameter of 0.4 μm to 20 μm, particularly 1 μm to 10 μm.

In the production method of the present invention, the intermediate phosphor is
It is preferable that the particles have a particle size concentration of 0.4 to 1.0, particularly 0.6 to 1.0.

Here, the particle size concentration is defined as d (n) where n is the particle size and A is the median particle size of the phosphor of the particles.
Is defined by the maximum value of x that satisfies xA ≦ d (n) ≦ A / x. In the present specification, the particle size concentration degree is:
It shall be determined from the result of observation of each particle by a scanning electron microscope. The particles to be measured are suitably about 50 particles arbitrarily selected from a particle group. The particle sphericity, which will be described later, is also determined from the results of observation of each particle by a scanning electron microscope.

In the production method of the present invention, the intermediate phosphor is
It is preferable that the particles mainly have a particle sphericity of 0.5 or more and 1.0 or less, particularly 0.7 or more and 1.0 or less.

Here, the particle sphericity means x as the maximum value of the length of a line segment connecting point a on the particle surface to point b on the surface different from point a, and When the point at which the perpendicular bisector intersects with the surface is point c and point d, and the minimum value of the length of the line segment connecting the point c and the point d is y,
It is determined by y / x.

In the production method of the present invention, it is preferable that the finally obtained phosphor be particles having substantially the same shape as the granular material contained in the phosphor material, like the intermediate phosphor. It is preferable that the particles be a group of particles having a median particle diameter that is equal to or greater than the median particle diameter of the granular material contained in the body material and less than twice the median particle diameter. Further, the median particle size of the finally obtained phosphor is 0.4 μm or more and 20 μm or more.
It is preferable that the thickness be not more than 1 μm, especially 1 μm or more and 10 μm or less. Further, it is preferable that the finally obtained phosphor is a particle group having a particle size concentration of 0.4 or more and 1.0 or less, particularly 0.6 or more and 1.0 or less. Further, the finally obtained phosphor is set to 0.5 or more and 1.0 or less, particularly 0.7
It is preferable that the particles mainly have a particle sphericity of 1.0 or more and 1.0 or less.

The shape of the phosphor obtained by the present invention is preferably spherical or pseudospherical (substantially spherical) as described above with reference to the particle sphericity, but is not limited thereto. Instead, it may be plate-shaped, regular octahedral, columnar, or the like.

According to one aspect of the present invention, there is provided a step of heating a raw material of a phosphor containing aluminum-containing particles in an oxidizing atmosphere to produce an intermediate phosphor, and a step of heating the intermediate phosphor in a reducing atmosphere. To produce an intermediate phosphor substantially identical to the granular material (preferably an aluminate intermediate phosphor containing trivalent rare earth ions), and further having substantially the same shape and / or particle size as the intermediate phosphor. This is a method for producing a trivalent rare earth ion-containing aluminate phosphor.

Another aspect of the present invention is that the phosphor material is heated at 1500 ° C. to 1900 ° C. in an oxidizing atmosphere and further heated at 1400 ° C. to 1800 ° C. in a reducing atmosphere. This is a method for producing a nate phosphor. One feature of one embodiment of the present invention is that the shape and the particle size are controlled by the phosphor raw material without using a reaction accelerator.

As described above, according to the present invention, it is possible to obtain a phosphor having a shape (particle size) that reflects the shape (particle size) of the granular material containing aluminum. On the other hand, since heating is performed in advance in an oxidizing atmosphere, heating in a reducing atmosphere that is so high that the shape of the granular material containing aluminum is not reflected is unnecessary. That is, heating in an oxidizing atmosphere compensates for characteristics obtained by high-temperature firing, such as the luminance characteristics of the phosphor. Thus, according to the present invention, for example, the particle size is substantially uniform and spherical or pseudo spherical,
An aluminate aluminate phosphor containing trivalent rare earth ions with high brightness can be obtained. As described above, this phosphor has improved heat-resistant deterioration characteristics and suppresses a time-dependent change in emission color during lighting.

In the present invention, the temperature is preferably 1500 ° C. or higher.
Heating is performed in an oxidizing atmosphere at 900 ° C. or lower. Heating in a reducing atmosphere need not be as high as heating in an oxidizing atmosphere. The heating temperature in a reducing atmosphere is preferably from 1400 ° C to 1800 ° C. Due to heating in an oxidizing atmosphere, tetravalent ions exist in the phosphor, albeit in trace amounts. However, this rare earth element is reduced to trivalent by heating in a reducing atmosphere and contributes to the color development of the phosphor.

In consideration of the characteristics desired in practical use, the practical heating temperature applicable in the manufacturing process, and the like, in one embodiment of the present invention, as described above, the heating temperature in an oxidizing atmosphere is reduced under a reducing atmosphere. Above the heating temperature.

Also in the present invention, in the heating step in a reducing atmosphere, there is a tendency that the shape (particle size) of the granular material is not accurately reflected as in the heating step in an oxidizing atmosphere. However, the object of the present invention can be achieved if, for example, a shape of a pseudo-spherical phosphor is obtained from a spherical granular material. A particularly important shape of the phosphor is a spherical shape or a pseudo spherical shape for improving the characteristics of the phosphor and the light emitting device.

In the production method of the present invention, when the intermediate phosphor is obtained in the form of aggregated particles, the step of disintegrating the aggregated intermediate phosphor is performed before the step of heating the intermediate phosphor. Is preferably performed. When the crushing process is performed, the particles are separated, so that the particle size concentration and the particle sphericity as described above can be clearly determined.

In the production method of the present invention, the intermediate phosphor is preferably a trivalent rare earth ion-containing aluminate compound, and particularly preferably a substantially single crystal phase trivalent rare earth ion-containing aluminate compound. Is preferred.

Further, in the manufacturing method of the present invention, unlike the conventional relationship between the preliminary firing and the main firing, the heating temperature in the reducing atmosphere is lower than the heating temperature in the oxidizing atmosphere, preferably the heating temperature in the oxidizing atmosphere. Is chosen to be less than.

In the production method of the present invention, it is preferable that the heating in the oxidizing atmosphere and / or the reducing atmosphere is performed twice or more.

As explained above, according to the present invention,
Any of the production methods described above, preferably a particulate trivalent rare earth ion-containing aluminate phosphor obtained from a phosphor raw material not containing a reaction accelerator, the trivalent having a spherical or pseudospherical shape A rare earth ion-containing aluminate phosphor can be provided. It is preferable that this phosphor has substantially the same shape as the granular material containing aluminum contained in the phosphor raw material. Further, it is preferable that the intermediate phosphor has a median particle diameter, a particle concentration degree, and a particle sphericity in the ranges exemplified above.

According to the present invention, (Ce _{1 -x} L _x )
(Mg _1-y M n _y ) Al ₁₁ O ₁₉ (where L is Sc, Y
And at least one element selected from the elements belonging to lanthanoids, x and y are mainly compounds represented by 0 ≦ x <1 and 0 ≦ y <1), and have a wavelength of 253.7 nm. A trivalent rare earth ion-containing aluminate phosphor having a ratio of the emission intensity at a wavelength of 380 nm to the emission intensity at a wavelength of 542 nm in photoluminescence obtained by irradiation with ultraviolet light of 0.020 or less and a particle concentration of 0.4 or more is used. Can be provided. L preferably contains at least Tb. x and y are preferably 0 ≦ x ≦ 0.5, 0 ≦ y ≦ 0.5
Is preferable.

The phosphor preferably has a particle sphericity of 0.5 or more and 1.0 or less.

The above compound obtained by the present invention is represented by (C)
e_1-xzTb_zL '_x) (Mg_1-yMn _y) Al₁₁O₁₉(T
However, L 'is the same as above except for Tb, and x and y are the same as above.
Thus, z is 0 ≦ z ≦ 0.5, preferably 0.25 ≦ z ≦
0.5 that satisfies 0.5).

Specific examples of the above compounds include (Ce
_{1-xz Tb z L 'x} ) MgAl 11 O 19 and the like. Another specific example of the above compound is (Ce _1-z Tb _z ) M
gAl ₁₁ O ₁₉ .

It is particularly preferable that L 'is at least one element selected from Sc, La and Gd.

Further, according to the present invention, it is possible to provide a light emitting device such as a fluorescent lamp having improved characteristics by using the above-mentioned trivalent rare earth ion-containing aluminate phosphor.

[0059]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the production method of the present invention will be described below. FIG. 1 is a flowchart applied to a preferred embodiment of the present invention.

First, in the phosphor raw material manufacturing step, raw material compounds are mixed so as to have a predetermined element ratio to prepare a phosphor raw material.

The starting compounds used include cerium compounds (cerium oxide, cerium carbonate, cerium nitrate,
Cerium oxalate, etc.), terbium compounds (terbium oxide, terbium carbonate, terbium nitrate, terbium oxalate, etc.), yttrium compounds (yttrium oxide, yttrium carbonate, yttrium nitrate, yttrium oxalate, etc.), magnesium compounds (magnesium oxide, magnesium carbonate, basic Magnesium carbonate, magnesium nitrate, magnesium oxalate, etc.), manganese compounds (manganese carbonate, metallic manganese, etc.), aluminum compounds (aluminum oxide, aluminum hydroxide, aluminum nitrate, etc.), rare earth compounds other than cerium, terbium and yttrium (scandium oxide, Lanthanum oxide,
Oxides such as praseodymium oxide and gadolinium oxide,
Examples thereof include nitrates and oxalates) and, for example, mixtures and composites thereof (such as yttrium terbium nitrate and cerium terbium oxalate). The starting compound may be an organic compound.

The particulate aluminum compound used as a raw material is appropriately selected in consideration of the preferred particle shape and particle size of the intermediate phosphor, and specifically, alumina powder is preferred. As such alumina powder, for example,
Spherical alumina fine powder (for example, trade name: alumina beads manufactured by Showa Denko KK) and plate-like alumina powder (YKK
And plate-like alumina powder). Further, as the alumina powder, α-alumina powder (manufactured by Sumitomo Chemical Co., Ltd., trade name: Advanced Alumina) is preferable (for “Advanced Alumina”, “Sumitomo Chemical” Masahide Mohri et al., 1996-II, 4- 14
Page).

It should be noted that the above-mentioned advanced alumina is Ins
It is an α-alumina powder produced by a local gas phase reaction in which a raw material and a reaction field almost coincide with each other, which is called itu Chemical Vapor Deposition, and has the following characteristics.

This is a single crystal α-alumina powder. It is a powder in a state close to monodispersion without aggregation. It is a powder whose particle size is precisely controlled. The particles are polyhedral and the surface is not a crushed surface but a crystal growth surface.
It is a powder in which no defect is observed as far as the structure inside the particle is evaluated by an ultra-high pressure transmission electron microscope. A powder with a sharp particle size distribution and few fine particles.

As the aluminum compound, α-alumina powder is preferable. This is because α-alumina is the most stable in the transformation of alumina and hardly undergoes transition even when heated.

These raw material compounds are mixed using a mixer such as a ball mill or an automatic mortar so as to have a predetermined element ratio, and become a phosphor raw material. The phosphor raw material can also be prepared by vacuum drying the frozen body of the phosphor raw material solution obtained by dropping an aqueous solution obtained by mixing the raw material compounds as a droplet in a solution cooled below the freezing point. It can also be adjusted by spray pyrolysis of a colloid solution containing metal nitrate. Also, a plurality of nitrates containing phosphor constituent elements are dissolved in water, ammonium hydroxide is added to the solution to obtain a precipitate, the precipitate is evaporated to dryness, and alumina powder is added and mixed. Can also be prepared.

In the intermediate phosphor manufacturing step, the phosphor raw material is fired in an oxidizing atmosphere to form an intermediate phosphor. The firing temperature of the phosphor raw material is preferably 1500 ° C. or more and 1900 ° C. or less. The firing temperature is 1600 ° C. or higher and 1700 ° C.
The following is more preferable, and the temperature is most preferably 1650 ° C or more and 1750 ° C or less. If the firing temperature in an oxidizing atmosphere is too low, it will be difficult to obtain sufficient light emitting performance. On the other hand, if the firing temperature in the oxidizing atmosphere is too high, it becomes difficult to obtain a phosphor having a particle shape derived from the phosphor raw material, or the particles may aggregate to form a particle diameter (particles) derived from the phosphor raw material. Size) is difficult to obtain.

In the above step, firing at 1600 ° C. or more can provide an intermediate phosphor which is a trivalent rare earth ion-containing aluminate compound having a single crystal phase. However, when firing at a temperature exceeding 1900 ° C., the intermediate phosphor may be melted. Here, the single crystal phase only needs to be substantially composed of a single phase.
Crystals in which 0% or more are single crystals are also included.

The heating step in an oxidizing atmosphere is preferably performed simply in the air.

In the heating step in an oxidizing atmosphere, before the heating in the reducing atmosphere, the granular material has a shape and size derived from the shape and size of the granular material, and preferably has a single crystal or an intermediate having good crystallinity close to a single crystal. This is performed to obtain a phosphor. On the other hand, a heating step (temporary firing) at a low temperature, which has been conventionally performed, is simply performed to activate the phosphor material to a state having high reactivity.

The crushing step is a step in which the aggregated intermediate phosphor is crushed and separated into individual particles. Specifically, various crushing means (automatic mortar, cross rotary mixer,
It is sufficient to break the intermediate phosphor using a ball mill or the like.

In the production process of the aluminate phosphor containing trivalent rare earth ions, the intermediate phosphor is heated in a reducing atmosphere. Specifically, the intermediate phosphor that has been crushed and separated,
Heating is performed in a reducing atmosphere using a phosphor manufacturing apparatus (atmosphere electric furnace, gas furnace, or the like). The heating temperature of the intermediate phosphor is preferably set to be equal to or lower than the heating temperature in an oxidizing atmosphere, and specifically, is preferably set to 1400 ° C or higher and 1800 ° C or lower.

If the heating temperature in the reducing atmosphere is too low, it becomes difficult to obtain a trivalent rare earth ion-containing aluminate phosphor exhibiting high luminous performance. On the other hand, if the heating temperature in the reducing atmosphere is too high, it becomes difficult to obtain a particle-shaped phosphor derived from the phosphor raw material. From such a viewpoint, the heating temperature in the reducing atmosphere is not less than 1500 ° C. and not less than 17 ° C.
Less than 00 ° C. is more preferred.

The heating step in a reducing atmosphere is preferably performed simply and in a mixed gas of nitrogen and hydrogen.

In this way, it is possible to obtain a phosphor having high brightness while controlling the shape and particle size by the phosphor material.

In the post-treatment step, the steps relating to the post-treatment such as the crushing step, the sieving step, the classification step, the washing step, and the drying step are carried out in an appropriate combination.

Hereinafter, changes in raw materials in each step will be described in more detail. When the phosphor raw material is fired in an oxidizing atmosphere (for example, in the air) in the intermediate phosphor production process, a chemical reaction occurs between the phosphor raw materials, and although the luminescent performance is poor, the particle shape and particles derived from the phosphor raw material are reduced. An intermediate phosphor having a size can be obtained. Furthermore, the intermediate phosphor can also be a trivalent rare earth ion-containing aluminate compound having a substantially single crystal phase by optimizing the heating conditions.

Although the intermediate phosphor has poor light emission performance,
The reason for having the particle shape and particle size derived from the phosphor material is that rare-earth ions having a valence higher than trivalent (for example, tetravalent terbium ion or tetravalent cerium ion) are mixed. Conceivable.

That is, light emission of the aluminate phosphor containing trivalent rare earth ions is caused by trivalent rare earth ions (trivalent cerium ion, trivalent terbium ion, etc.). However, in the intermediate phosphor obtained by heating the phosphor material in an oxidizing atmosphere, a trace amount of tetravalent rare earth ions (tetravalent terbium ions, tetravalent cerium ions, etc.) are mixed in addition to trivalent ions. . When rare earth ions having a valence higher than trivalence are mixed in the aluminate phosphor containing trivalent rare earth ions, the emission intensity of the phosphor is reduced. This is because the emission of the aluminate phosphor containing trivalent rare earth ions is based on the electron energy transition of the trivalent rare earth ions.

On the other hand, the crystal of the aluminate phosphor containing a trivalent rare earth ion has a sufficient atomic arrangement when the rare earth ions are all trivalent, and exhibits good crystallinity. Originally, the crystal structure of the trivalent rare earth ion-containing phosphor is different from any crystal structure of each compound constituting the phosphor raw material. However, when a small amount of tetravalent rare earth ions are present, these ions act to disturb the atomic arrangement of the phosphor. For this reason, the trivalent rare earth ion-containing phosphor does not have a different structure from the original crystal structure of the phosphor, but rather easily reflects the particle shape of the phosphor raw material.

For the above reasons, when the phosphor raw material of the trivalent rare earth ion-containing aluminate phosphor is reacted in an oxidizing atmosphere, the particle shape and particle size derived from the phosphor raw material are deteriorated, although the luminous performance is inferior. Provided intermediate phosphor can be obtained.

The inventors have confirmed that the luminance of the intermediate phosphor obtained by firing in an oxidizing atmosphere has a wavelength of 254.
When evaluated by photoluminescence caused by irradiation of (253.7) nm ultraviolet rays, it is only 70 to 95% of that when firing in a reducing atmosphere. However, when the phosphor raw material is simply heated in a reducing atmosphere without being heated in an oxidizing atmosphere, the shape of the granular material contained in the raw material starts to collapse at 1200 to 1400 ° C., and the shape of the granular material is completely reflected at 1600 ° C. Will not be.

In the crushing step, when the aggregated intermediate phosphor is crushed, particles having the shape and size derived from the phosphor raw material are obtained in a separated state.

In the step of producing the aluminate phosphor containing trivalent rare earth ions, the intermediate phosphor is heated in a reducing atmosphere, and its luminous performance is improved while substantially maintaining the particle shape and particle size. Because the shape and size are maintained, the median particle size,
The characteristics such as the particle size concentration and the particle sphericity are substantially the same.

On the other hand, the light emission performance is such that rare earth ions (tetravalent terbium ion, tetravalent cerium ion, etc.) contained in the intermediate phosphor are reduced to trivalent rare earth ions. To be improved for. However, since heating is performed in a predetermined temperature range (for example, a temperature range lower than the heating temperature in an oxidizing atmosphere), the movement of atoms inside the intermediate phosphor is suppressed. Therefore, the particle shape of the intermediate phosphor derived from the phosphor raw material is maintained.

As described above, after the phosphor material of the trivalent rare earth ion-containing aluminate phosphor is heated in an oxidizing atmosphere to obtain an intermediate phosphor, the heating is performed in a reducing atmosphere at a temperature lower than the heating temperature in the oxidizing atmosphere. When heated in this manner, a trivalent rare earth ion-containing aluminate phosphor having a particle shape and a particle size derived from the phosphor raw material and having excellent light emission performance can be produced.

Further, a spherical or near-spherical pseudo-spherical phosphor material (obtained by vacuum-drying spherical particulate alumina or a frozen material of the phosphor material solution or spray pyrolysis of a colloid solution) is used. And spherical particle phosphor materials)
Is used, the shape of the phosphor raw material is reflected in the particle shape of the phosphor, and as described above, a three-dimensional particle having a spherical or pseudo-spherical particle shape that has the effect of increasing the transmission luminance and the reflection luminance of the phosphor film. A valent rare earth ion-containing aluminate phosphor can be obtained.

In the above embodiment, a process in which a phosphor raw material manufacturing process, an intermediate phosphor manufacturing process, a disintegration process, a trivalent rare earth ion-containing aluminate phosphor manufacturing process, and a post-treatment process are sequentially combined has been described. The combination of steps in the method for producing a trivalent rare earth ion-containing aluminate phosphor of the present invention is not limited to the above.

Hereinafter, the emission luminance of the phosphor will be described in more detail. Here, C is used as the trivalent rare earth element.
includes a Tb ³⁺ in addition to e ^3+, described trivalent rare earth ion-containing aluminate phosphor that emits green light.

The fluorescent material is irradiated with ultraviolet light (for example, wavelength 253.
7 nm), the energy of this ultraviolet light becomes Ce
Is absorbed in the ^3+, Tb ³⁺ emits green energy Ce ³⁺ is absorbed by Tb ³⁺ absorption (peak wavelength 542n
m; green). When the energy does not transition to Tb ³⁺ , Ce ³⁺ emits light (peak wavelength around 350 nm;
Purple-blue).

If the crystallinity of the phosphor is not sufficient,
Due to defects in the body, Ce³⁺From Tb ³⁺Of energy to
Transition is inhibited. Degree of inhibition of this energy transition
Is Tb³⁺Ce against emission intensity³⁺Luminous intensity
It can be evaluated by measuring the degree ratio.

FIG. 7 shows that a phosphor having good crystallinity (solid line) and a phosphor having many defects (dashed line) have a wavelength of 253.
An example of a photoluminescence spectrum obtained by irradiating a 7 nm ultraviolet ray is shown.

When the present invention is applied, as shown in the following examples, a phosphor having good crystallinity and inhibiting the above-mentioned energy transition is suppressed while controlling the shape and the like by the granular material contained in the raw material. be able to.

Hereinafter, preferred embodiments of the fluorescent lamp to which the present invention can be applied will be described with reference to the drawings.

FIGS. 8, 9 and 10 show a ring-type fluorescent lamp, a bulb-type fluorescent lamp and a twin-type fluorescent lamp, respectively. In the ring-shaped fluorescent lamp 60, the glass tube is bent into a ring shape so that the fluorescent lamp 61 contacts both ends. In the bulb-type fluorescent lamp 70, the bent fluorescent lamp 71 is replaced with a globe 7 coated with a light diffusing substance 72.
3 is covered, and a base 74 of the same type as the electric bulb is attached. In the twin-type fluorescent lamp 80, two fluorescent lamps 81 and 82 arranged in parallel are processed so as to conduct near the front end.

The phosphor provided by the present invention is not limited to the above-described fluorescent lamp, but may be any of various light-emitting devices (plasma display, CRT (Cathod Ray-Tube), FED (Field
Emission Display). A pseudo-spherical phosphor having a uniform particle size has a high bulk density. Therefore, when the phosphor according to the present invention is used, the density of the phosphor film can be increased. When the density of the fluorescent film increases, the luminous flux of the light emitting device can be increased. In addition, as described above, when a pseudo-spherical phosphor having a uniform particle size is used, the heat deterioration characteristic of the phosphor is improved.

[0097]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.

In this embodiment, Ce _0.6 Tb _0.4 MgAl ₁₁
A green-emitting trivalent rare earth ion-containing aluminate phosphor represented by the chemical formula of O ₁₉ (hereinafter referred to as “CeMgAl ₁₁ O ₁₉ : Tb”)
³⁺ phosphor ").

Considering the energy transition from Ce ³⁺ to Tb ³⁺ , Tb with respect to the number of (Ce + Tb) atoms
The ratio of the number of atoms is preferably from 0.25 to 0.5.

The raw materials for the CeMgAl ₁₁ O ₁₉ : Tb ³⁺ phosphor are cerium oxide (purity 99.9%), terbium oxide (purity 99.9%), and basic magnesium carbonate (purity 9).
9.99%), alumina (aluminum oxide: purity 9)
9.999%). Note that no reaction accelerator was used.

As the aluminum oxide, "Advanced Alumina" manufactured by Sumitomo Chemical Co., Ltd. was used. This α
When the alumina powder was observed with an electron microscope, no crushed surface was observed, and the particle sphericity described above was 0.7 to
It was composed of coagulated particles of about 0.9. Also,
When the particle size distribution was measured, the median particle size was about 5 μm,
The particle diameter concentration described above had a uniform particle diameter of about 0.41. The particle size distribution was measured using a laser micron sizer.

First, as a phosphor raw material production process, 5.16 g of cerium oxide, 3.74 g of terbium oxide, 4.80 g of basic magnesium carbonate, and 28.50 g of aluminum oxide were used.
05g was mixed using an automatic mortar for 1 hour and mixed with CeMgA.
l ₁₁ O ₁₉ : Tb ³⁺ phosphor raw material was obtained.

Next, as an intermediate phosphor manufacturing process, CeM
The gAl ₁₁ O ₁₉ : Tb ³⁺ phosphor raw material was charged into an alumina boat, placed in a box-type electric furnace, and fired in the air for 2 hours to obtain a CeMgAl ₁₁ O ₁₉ : Tb ³⁺ intermediate phosphor. The firing temperature for this primary firing was 1650 ° C.

FIG. 2 shows an X-ray diffraction pattern of the CeMgAl ₁₁ O ₁₉ : Tb ³⁺ intermediate phosphor. According to FIG. 2, this intermediate phosphor is a single crystal phase of Ce _0.6 Tb _0.4 MgAl ₁₁ O ₁₉
It was confirmed that the compound was a trivalent rare earth ion-containing aluminate compound.

Further, as a crushing step, CeMgAl ₁₁
The O ₁₉ : Tb ³⁺ intermediate phosphor was crushed for 10 minutes using an automatic mortar. FIG. 3 shows aluminum oxide as a raw material (FIG. 3A), CeMgAl ₁₁ O ₁₉ : T before crushing treatment.
b ³⁺ intermediate phosphor (FIG. 3B), CeMg after crushing
The results of observing the Al ₁₁ O ₁₉ : Tb ³⁺ intermediate phosphor (FIG. 3C) with an electron microscope are shown.

By comparing FIG. 3A and FIG. 3C,
It can be seen that the particle shape of the CeMgAl ₁₁ O ₁₉ : Tb ³⁺ intermediate phosphor after the crushing treatment is substantially the same as the particle shape of aluminum oxide. By comparing FIG. 3B and FIG. 3C, it was found that Ce aggregated after the intermediate phosphor manufacturing step.
It can also be confirmed that each particle of the MgAl ₁₁ O ₁₉ : Tb ³⁺ intermediate phosphor was separated into individual particles by the crushing treatment.

Also, CeMgAl ₁₁ O ₁₉ after the crushing treatment:
When the particle sphericity and particle size distribution of the Tb ³⁺ intermediate phosphor were measured in the same manner as in the α-alumina powder used as the raw material, the particle sphericity was 0.5 to 0.7, and the particle concentration was 0.4.
0, the median particle size was 6.6 μm.

[0108] Figure 4, the aluminum oxide as a raw material, crushing processes prior to the CeMgAl ₁₁ O _19: Tb ³⁺ intermediate phosphor after the cracking treatment CeMgAl ₁₁ O _19: particle size distribution curve of Tb ³⁺ intermediate phosphor Is shown.

FIG. 4 shows that the crushed CeMgAl ₁₁ O
₁₉ : The median particle size of the Tb ³⁺ intermediate phosphor is in the range of 1 to 2 times the median particle size of aluminum oxide, and the median particle size of the CeMgAl ₁₁ O ₁₉ : Tb ³⁺ intermediate phosphor is obtained by a crushing treatment. It can be confirmed that the particle size was reduced from about 10 μm to about 6.6 μm.

Further, as a process for producing a trivalent rare earth ion-containing aluminate phosphor, CeMgA after the crushing treatment was performed.
The ₁₁ O ₁₉ : Tb ³⁺ intermediate phosphor was charged in an alumina boat, placed in a tubular atmosphere furnace, and fired for 2 hours in a reducing atmosphere consisting of a mixed gas of nitrogen and hydrogen. The firing temperature for this secondary firing was 1600 ° C. The flow rates of nitrogen and hydrogen were 380 cc / min and 20 cc / min, respectively. In the present embodiment, the post-processing steps described above are omitted.

The thus obtained CeMgAl ₁₁ O ₁₉ : Tb ³⁺
For the phosphor (hereinafter referred to as "Example phosphor"), the particle sphericity and the particle size distribution were measured in the same manner as for the α-alumina powder used as the raw material.
7, the particle size concentration is 0.40, the median particle size is 8.3 μm
Met.

Further, the luminance and chromaticity of the phosphor of the example were evaluated using a luminance and chromaticity measuring device. In addition,
A low-pressure mercury lamp was used for evaluation of luminance and chromaticity.
_The evaluation was performed by irradiating the ₁₁ O ₁₉ : Tb ³⁺ phosphor with ultraviolet rays having a wavelength of 254 nm.

For comparison, a conventional production method (reaction acceleration) was used.
CeMgAl₁₁O ₁₉: Tb³⁺Phosphor
It was manufactured separately and evaluated similarly. This phosphor is specifically
In the above process, the intermediate phosphor manufacturing step and the crushing step
Is omitted, and CeMgAl obtained in the phosphor raw material manufacturing process is omitted.₁₁O
₁₉: Tb³⁺Phosphor raw material in a nitrogen-hydrogen mixed atmosphere at a predetermined temperature
For 2 hours. Raw materials and equipment used
Same as above. Hereinafter, the firing temperature was 1600 ° C.
The phosphor is “comparative phosphor A” and the firing temperature is 1700 ° C.
The phosphor thus obtained is indicated as “comparative phosphor B”.

Further, commercially available CeMgAl ₁₁ O ₁₉ : Tb
^{The 3+} phosphor (hereinafter referred to as “commercial phosphor”) was similarly evaluated. In the phosphor manufacturing process, aluminum fluoride is used as a reaction accelerator. Table 1 shows the results of the evaluation of each phosphor.

As one of the evaluations, the emission intensity ratio was measured.
This emission intensity ratio is the same as the wavelength 542 in the photoluminescence obtained by irradiation with ultraviolet light having a wavelength of 253.7 nm.
It is a ratio of the emission intensity at a wavelength of 380 nm to the emission intensity at nm.

(Table 1) ―――――――――――――――――――――――――――――――― CeMgAl ₁₁ O ₁₉ : Tb ³⁺ fluorescence Body Relative luminance Chromaticity Emission intensity ratio (%) (x, y) ―――――――――――――――――――――――――――――――― Example phosphor 103 (0.3235, 0.5950) 0.016 (manufactured via intermediate phosphor) Comparative phosphor A 79 (0.3179, 0.5862) 0.046 (directly heated at 1600 ° C.) Comparative phosphor B 90 (0.3204, 0.5932) ) 0.038 (direct heating at 1700 ° C) Commercial phosphor 100 (0.3209, 0.5932) 0.016 (using reaction accelerator) ――――――――――――――――――――――――― ―――――――――

As shown in Table 1, the relative luminance of the example phosphor was higher than any of the two kinds of comparative phosphors, and was slightly higher than the commercial phosphor. As described above, according to the above manufacturing method, at least under a chromaticity range that can be regarded as the same, the luminance is higher than that of the phosphor produced by the conventional method, and the phosphor produced by using the reaction accelerator. A CeMgAl ₁₁ O ₁₉ : Tb ³⁺ phosphor that emits light at a luminance 3% higher than that of the phosphor can be manufactured.

Further, the luminescence intensity ratio could be suppressed to a level where the luminescence due to Ce ³⁺ was substantially absent (0.020 or less).

In this embodiment, CeM having high luminance is used.
gAl₁₁O₁₉: Tb³⁺The phosphor was obtained in a reducing atmosphere.
Cerium tetravalent by heating at high temperature (1600 ° C)
Because the mixture of on and tetravalent terbium ions could be eliminated.
Yes, and for two degrees of heating at about 1600-1700 ° C
Therefore, CeMgAl with excellent crystal quality₁₁O₁₉: Tb ³⁺
It is considered that the phosphor could be manufactured.

As partially described above, FIG. 5 shows CeMg obtained by sintering the phosphor material as it is in a reducing atmosphere.
The relationship between the firing temperature of Al ₁₁ O ₁₉ : Tb ³⁺ phosphor and the relative luminance was determined by using CeMgAl ₁₁ O produced using a reaction accelerator.
_{FIG. 19} is a diagram showing the luminance of a commercially available phosphor of Tb ³⁺ as 100. In the method in which heating is performed directly in a reducing atmosphere, high brightness can be obtained by increasing the firing temperature.
In order to obtain a high brightness comparable to l ₁₁ O ₁₉ : Tb ³⁺ commercial phosphor, it is necessary to raise the firing temperature to 1700 ° C. or higher, and to obtain a phosphor reflecting the particle shape of the phosphor raw material Can not.

As partially described above, FIG. 6 shows aluminum oxide (FIG. 6 (a)) as a raw material, an example phosphor (FIG. 6 (b)), and a comparative example phosphor B (FIG. 6 (a)). c)), comparative phosphor A (FIG. 6 (d)), and commercially available phosphor (FIG. 6).
It is an electron microscope photograph of (e)). FIG. 6A and FIG.
From the comparison with (b), the particle shape of the Example phosphor manufactured via the intermediate phosphor is substantially the same as the particle shape of the aluminum oxide used as the raw material, and is a pseudo-spherical shape close to a sphere.
It can be seen that the particle size distribution is almost the same as the particle size distribution of the aluminum oxide used as the raw material, and is a uniform particle size distribution. Further, from FIG. 6B, the particles of the phosphor of the example according to the present invention have a large number of plate-like crystals overlapping with each other.
It can also be seen that it has the characteristic of forming a pseudo-sphere close to a sphere. On the other hand, in the comparative phosphor A having the heating temperature of 1600 ° C. (FIG. 6D), a pseudo-spherical particle shape almost the same as the aluminum oxide particle shape was obtained, but the firing temperature was 1700 ° C. A comparative phosphor B (FIG. 6)
In (c)), the shape of the aluminum oxide was not reflected at all, and the phosphor particles were non-uniform and irregular. Furthermore, the phosphor produced using the reaction accelerator (FIG. 6E) has a non-uniform particle size. The particle shape was a slightly rounded hexagonal plate.

The phosphor of the example has an appearance in which flaky crystals are stacked (FIG. 6B). As described above, according to one embodiment of the present invention, a phosphor having a pseudospherical shape and a layered structure can be obtained. On the other hand, when a reaction accelerator is added, a phosphor having a smooth surface is obtained (FIG. 6).
(E)). The difference in appearance of the phosphor depending on the presence or absence of the reaction accelerator can be easily confirmed by observation using an electron microscope.

The particle sphericity and the particle size distribution of the comparative phosphor B and the commercially available phosphor were measured in the same manner as described above. , Particle size concentration 0.2, median particle size 1
1.3 μm, and the commercial phosphor had a particle sphericity of 0.4 to 0.8, a particle diameter concentration of 0.36, and a median particle diameter of 8.3 μm.

As described above, according to the present invention, a pseudospherical trivalent rare earth ion-containing aluminate phosphor having a controlled particle size and shape and high light emission performance can be manufactured.

In the embodiment, the case where a phosphor material containing a particulate α-alumina material which does not substantially have a crushed surface is used has been described. Can be widely applied to a production method using a phosphor raw material containing a particulate aluminum compound having

Further, an aqueous solution obtained by mixing a raw material compound which can be a raw material of a phosphor is dropped as a droplet in a solution cooled below the freezing point. The colloid solution containing the compound and metal nitrate was adjusted by spray pyrolysis, etc.,
In the case of the production method of the present invention using a particulate phosphor material, the same action and effect can be observed.

Further, in this embodiment, CeMgAl
_{Although the} description has been given of the ₁₁ O ₁₉ : Tb ³⁺ phosphor, the production method of the present invention can be widely applied to the aluminate phosphor containing trivalent rare earth ions.

For example, even if 0 to 30% of Ce or Tb was substituted with Sc or the like in the above compound, a green phosphor having similar characteristics could be produced. This substituted compound is, for example, (Ce _1-x Tb _x ) _1-p M _p (Mg _1-y
M n _y ) Al ₁₁ O ₁₉ (where M is at least one element selected from Sc, Y and elements other than Tb belonging to lanthanoids (preferably at least one element selected from Sc, Y, La and Gd) ), X, y and p are respectively 0 ≦ x <1, 0 ≦ y <1 and 0 ≦ p
≤ 0.3).

Thus, a part of Ce or Tb is replaced with Sc
(1) Since the ionic radius of these elements is different from that of Ce or Tb, the lattice constant of the crystal in the phosphor slightly increases or decreases. Ce (253.7 nm)
^The effect of increasing or decreasing the excitation efficiency of ³⁺ or Tb ³⁺ ions appears slightly, or (2) the melting point of the trivalent rare earth ion-containing aluminate phosphor slightly increases or decreases. The effect of changing the crystallinity of the phosphor when manufactured is slightly exhibited.

By utilizing this effect, Ce _0.6 Tb _0.4 M
The relative luminance of the green phosphor mainly composed of the compound represented by the chemical formula of gAl ₁₁ O ₁₉ is expressed by CeMgAl ₁₁ O ₁₉ : Tb.
90% to 105%, with the luminance of the ³⁺ green phosphor as 100%
Can be controlled within the range.

Note that the absolute value of the brightness varies depending on the manufacturing conditions (firing atmosphere, firing temperature, firing time, firing frequency, etc.) of the trivalent rare earth ion-containing aluminate phosphor.

Further, Ce (III) MgAl₁₁O₁₉, C
e (III) MgAl₁₁O₁₉: Mn²⁺, CeMgAl₁₁O
₁₉: Tb³⁺, Mn²⁺Such as aluminate phosphor, Y_Three
Al_FiveO ₁₂: Tb³⁺, Y_ThreeAl_FiveO₁₂: Ce³⁺With the chemical formula
Trivalent rare earth ion-containing aluminate phosphor,
CeAl₁₂O₁₈N: Tb³⁺Oxynitride phosphors such as
By applying the method of the present invention, the same effect as in the above embodiment can be obtained.
I got it.

When the aluminate phosphor containing trivalent rare earth ions is produced by using the conventional production method, CeAlO 2 is difficult to maintain the particle shape and particle size derived from the phosphor material as an intermediate product. ₃ and TbAlO ₃
It has been confirmed by X-ray diffraction evaluation of crystal constituents that a trivalent rare earth ion-containing aluminate compound such as YAlO ₃ or YAlO ₃ is easily produced.

In the above embodiment, the case where the number of firings in the oxidizing atmosphere and the number of firings in the reducing atmosphere are each one has been described. However, the intermediate phosphor and the trivalent rare earth ion-containing aluminate phosphor were replaced with the phosphor. As long as the number of firings is increased within a range in which the particle shape derived from the raw material is maintained, higher luminous performance can be obtained. However, when the heating step is performed a plurality of times, it is necessary to pay particular attention so that impurities are not mixed.

[0135]

As described above in detail, according to the present invention, an intermediate phosphor obtained by preliminarily heating a phosphor material in an oxidizing atmosphere is heated in a reducing atmosphere to a temperature lower than the heating temperature in the oxidizing atmosphere. Because it was decided to obtain the phosphor by heating at a temperature, a trivalent rare earth ion-containing aluminate phosphor having a particle shape and a particle size derived from the phosphor raw material and having excellent light emission performance, particularly, spherical or A pseudospherical phosphor can be provided. Thus, the present invention solves the problems specific to the trivalent rare earth ion-containing aluminate phosphor, and provides extremely high utility value in the technical field to which the present invention belongs.

[Brief description of the drawings]

FIG. 1 is a flowchart showing one embodiment of a method for producing a trivalent rare earth ion-containing aluminate phosphor of the present invention.

FIG. 2 is an X-ray diffraction pattern of an intermediate phosphor obtained in an example of the present invention.

FIG. 3 shows (a) aluminum oxide used in an example of the present invention, (b) an intermediate phosphor before crushing treatment obtained in the example,
(C) is an electron micrograph of the intermediate phosphor after the crushing treatment.

FIG. 4 shows an aluminum oxide used in an embodiment of the present invention;
It is a figure which shows the particle size distribution of the intermediate phosphor before the disintegration process obtained by the same Example, and the intermediate phosphor after a disintegration process.

FIG. 5: CeMgA manufactured using a conventional manufacturing method
l ₁₁ O _19: it is a diagram showing the relationship between the firing temperature and the relative luminance of the Tb ³⁺ phosphor.

FIG. 6 shows (a) aluminum oxide used in the examples of the present invention, (b) trivalent rare earth ion-containing aluminate phosphor obtained in the examples, and (c) first alumina manufactured by a conventional manufacturing method. (D) a second comparative phosphor (calcination temperature: 1600 ° C.)
C) and (e) Electron micrographs of a commercially available phosphor.

FIG. 7 is a diagram showing an example of a spectrum of the phosphor of the present invention.

FIG. 8 is a plan view showing an annular fluorescent lamp as an example of the light emitting device of the present invention.

FIG. 9 is a partially cutaway view showing a light bulb shaped fluorescent lamp as an example of the light emitting device of the present invention.

FIG. 10 is a plan view showing a twin-type fluorescent lamp as an example of the light-emitting device of the present invention.

[Explanation of symbols]

 Reference Signs List 60 ring-shaped fluorescent lamp 61, 71, 81, 82 fluorescent lamp 70 bulb-shaped fluorescent lamp 72 light-diffusing substance 73 globe 74 base 80 twin-type fluorescent lamp

Claims (15)

[Claims] A step of heating a phosphor raw material containing aluminum-containing particles at a predetermined temperature in an oxidizing atmosphere to produce an intermediate phosphor, and a step of heating the intermediate phosphor in a reducing atmosphere at a temperature lower than the predetermined temperature. A method of producing a trivalent rare earth ion-containing aluminate phosphor, comprising a step of heating. 2. The method for producing a trivalent rare earth ion-containing aluminate phosphor according to claim 1, wherein the aluminum-containing granular material is a particulate aluminum-containing compound. 3. The method for producing a trivalent rare earth ion-containing aluminate phosphor according to claim 1, wherein the phosphor material does not contain a reaction accelerator. 4. The method for producing a trivalent rare earth ion-containing aluminate phosphor according to claim 1, wherein the granular material containing aluminum is α-alumina powder. 5. The method for producing a trivalent rare earth ion-containing aluminate phosphor according to claim 4, wherein the α-alumina powder has substantially no crushed surface. 6. The aluminate phosphor containing a trivalent rare earth ion is (Ce _1-x L _x ) (Mg _1-y M n _y ) Al ₁₁ O ₁₉ (where L is an element belonging to Sc, Y and a lanthanoid) 2. The trivalent rare earth ion according to claim 1, wherein at least one element selected from the group consisting of x and y is mainly a compound represented by 0 ≦ x <1 and 0 ≦ y <1). Method for producing aluminate-containing phosphor. 7. The method for producing a trivalent rare earth ion-containing aluminate phosphor according to claim 6, wherein L contains Tb. 8. A heating temperature in an oxidizing atmosphere of 1500
The method for producing a trivalent rare earth ion-containing aluminate phosphor according to claim 1, wherein the temperature is not lower than 1900C and not higher than 1900C. 9. A heating temperature in a reducing atmosphere of 1400
2. The method for producing a trivalent rare earth ion-containing aluminate phosphor according to claim 1, wherein the temperature is not lower than 1800C and not higher than 1800C. 10. A process for manufacturing an intermediate phosphor by heating a phosphor raw material containing a granular material containing aluminum at a predetermined temperature in an oxidizing atmosphere, and heating the intermediate phosphor in a reducing atmosphere at a temperature not higher than the predetermined temperature. A particulate trivalent rare earth ion-containing aluminate phosphor obtained by a production method including a heating step, wherein the aluminate phosphor has a spherical or pseudospherical shape. 11. The aluminate phosphor containing trivalent rare earth ions according to claim 10, which is obtained from a phosphor raw material containing no reaction accelerator. 12. _{(Ce 1-x L x)} (Mg 1-y Mn y) Al
₁₁ O ₁₉ (where L is at least one element selected from Sc, Y and lanthanoid elements, and x and y are numerical values satisfying 0 ≦ x <1 and 0 ≦ y <1, respectively) And a trivalent rare earth ion-containing aluminate phosphor mainly comprising the compound to be obtained, wherein the ratio of the emission intensity at a wavelength of 380 nm to the emission intensity at a wavelength of 542 nm in photoluminescence obtained by irradiation with ultraviolet light having a wavelength of 253.7 nm is 0.020. A trivalent rare earth ion-containing aluminate phosphor, wherein the degree of particle size concentration is 0.4 or more. Here, the particle size concentration degree is defined as xA ≦ d, where d (n) is the particle size of each of the n particles, and A is the median particle size of the phosphor of the n particles.
(N) It is determined by the maximum value of x that satisfies ≤A / x. 13. The aluminate phosphor containing trivalent rare earth ions according to claim 12, wherein the spherical degree of the particles is 0.5 or more and 1.0 or less. Here, the particle sphericity is defined as x, the maximum value of the length of a line segment connecting point a on the particle surface to point b on the surface different from the point a, and perpendicular bisecting the line segment. When the point at which the line intersects with the surface is point c and point d, and the minimum value of the length of the line segment connecting point c and point d is y, it is determined by y / x. 14. The aluminate phosphor containing trivalent rare earth ions according to claim 12, wherein L contains Tb. 15. A light-emitting device using the phosphor according to claim 10. Description: