JP2002220587A - Method for producing high-luminance light emitting material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing fine powder of highly crystalline high-luminance light emitting material by a safe and simple operation. SOLUTION: In producing a high-luminance light emitting material (e.g. SrAl2O4:Eu) comprising one or more kinds of aluminates as a parent body substance and one or more kinds of metal ions of rare earth metal ions or transition metal ions as the central ion of light emitting center in the parent body substance, an aluminum alcoholate is mixed with one or more kinds of water-soluble compounds of a metal except aluminum in an aqueous medium, changed into alkalinity and made into a colloid. A dispersion stabilizer is added to the colloid, rapidly dried to form a dried substance having the dispersion stabilizer attached to the surface of colloidal particle. The dried material is calcined in an oxidizing atmosphere at 500-900 deg.C. The calcined material is ground, the obtained powder is molded or not molded and fired in a reducing atmosphere at 1,000-1,700 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing various luminous bodies which emit light by stress excitation, ultraviolet excitation, plasma excitation, electron beam excitation, electric field excitation, etc. The present invention relates to a novel method for producing a high-luminance luminescent material containing a metal as a central ion of a luminescent center.

[0002]

2. Description of the Related Art Heretofore, as a luminous body which emits light by an external stimulus, a luminous body for a fluorescent lamp, a luminous body for a plasma display, and the like, which are excited by ultraviolet rays, have been known.
Thermal excitation, such as phosphor for high-speed electron excitation and phosphor for fluorescent display tube, etc. for X-ray and radiation excitation, and solid scintillator for X-ray and radiation excitation.
Phosphorescent phosphors, stimulable phosphors, infrared-visible conversion phosphors and the like are known as those excited by infrared rays.

In addition, the present inventors have proposed that a carrier which is made of at least one kind of aluminate having a non-stoichiometric composition and which emits light by a mechanical external force, and which is excited by mechanical energy, has a ground state. High luminance comprising a substance having lattice defects that emit light upon returning to the substrate, or a substance containing at least one kind of metal ion selected from rare earth metal ions and transition metal ions as a central ion of the emission center in the base substance. A stress-stimulated luminescent material has been proposed (Japanese Patent Application No. 11-223516).

[0004] These luminescent materials are generally prepared by a solid phase reaction method,
That is, it is manufactured by a method in which raw materials for producing a predetermined composition are mixed in a powder form, fired at a high temperature, and subjected to a solid-phase reaction between the raw materials. In order to promote the reaction at this time, for example, boric acid, sodium hydroxide, ammonium chloride, or the like is used as a flux agent for promoting the formation of a liquid phase at a high temperature.

[0005] However, such a solid-phase reaction method is
Generally, the particles of the luminescent material generated tend to be coarse, and it is difficult to obtain fine powder. Although a method of reacting in an organic solvent to form fine particles is also known, it is necessary to consider environmental pollution and the effect on the human body due to the use of the organic solvent, and the cost increases. In addition, the resulting fine powder has low crystallinity, so that sufficient emission luminance cannot be obtained.

[0006]

SUMMARY OF THE INVENTION Under the above circumstances, the present invention overcomes the drawbacks of the conventional method and provides a high-luminance, high-crystallinity, high-luminance luminescent material by a safe and simple operation. The purpose is to obtain fine powder.

[0007]

The present inventors have conducted intensive studies on a method for producing a high-quality, high-luminance luminescent material. As a result, the present inventors have found that aluminum alcoholate is used as a raw material for aluminum, and a component metal other than aluminum, such as an alkali metal, is used. Earth water, rare earth metal, as a raw material of the transition metal, using their water-soluble and gelatinizable compounds,
An aqueous solution containing these together with boric acid is made alkaline to form a colloid, and the obtained colloid particles are dried in the presence of a dispersion stabilizer to provide a stabilized, high-brightness, high-crystalline, high-brightness luminescent material. It has been found that if the fine powder is obtained, the fine powder is preliminarily baked, and then ground and baked, a high-quality high-luminance light-emitting material can be obtained, and the present invention has been made based on this finding. .

That is, according to the present invention, at least one kind of aluminate is used as a host substance, and at least one kind of metal ion selected from rare earth metal ions and transition metal ions is used as a central ion of a luminescence center. In producing a high-brightness light-emitting material containing aluminum alcoholate and at least one water-soluble compound of a component metal other than aluminum in an aqueous medium, the mixture is converted to alkalinity to form a gel, and then a dispersion stabilizer is added thereto. And dried rapidly to form a dried product having a dispersion stabilizer attached to the surface of the colloidal particles.
The calcined product is calcined at 00 ° C., the calcined product is pulverized, and the obtained powder is molded or not molded in a reducing atmosphere at 1000 to 170 ° C.
An object of the present invention is to provide a method for producing a high-luminance light-emitting material, which is characterized by firing at 0 ° C.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION As an aluminate constituting a base substance in a high-luminance light-emitting material aimed at by the method of the present invention, for example, a general formula M _x Al _y O _{2x + 3y / 2} (where M is an alkaline earth element) Metals, transition metals or rare earth metals, x and y are integers). Examples of the alkaline earth metal of M include Mg, Ca, Ba and Sr, Zn as a transition metal, and rare earth. Y is preferred as the metal. The rare earth metal forming the central ion of the emission center is Sc, Y, La, Ce, Pr, Nd, Pm,
Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Y
b, Lu, etc., preferably Y, Ce, Eu, Tb, and transition metals such as Sb, Ti, Zr, V, Cr,
Mn, Fe, Co, Ni, Cu, Zn, Nb, Mo, T
a, W, etc., preferably Sb, Mn or Mo.

An aluminate having a lattice defect in which the alkaline earth metal in the above general formula is stoichiometrically deviated from 0.01 to 20 mol% is used as a base material, and a rare earth metal ion or a transition metal ion is added thereto. A material containing 0.01 to 10 mol% as the ion of the luminescent center is a high-luminance stress-luminescent material. According to the method of the present invention, SrMgAl
An ultraviolet-excited phosphor using ₁₀ O ₁₇ , BaMg ₂ Al ₁₆ O ₂₇ or YAlO ₃ as a base substance and Eu as a central ion of a light emission center can also be manufactured.

In the method of the present invention, it is necessary to use aluminum alcoholate as the aluminum feedstock. Examples of the aluminum alcoholate include monomethoxydiethoxyaluminum, triethoxyaluminum, monopropoxydiethoxyaluminum, tripropoxyaluminum, and triisopropoxyaluminum.

Next, as a water-soluble compound of an alkaline earth metal used as a supply material of the alkaline earth metal, for example, magnesium chloride, calcium chloride, barium chloride,
Calcium nitrate, strontium nitrate, barium sulfate,
Examples thereof include magnesium carbonate and magnesium sulfate.

The rare-earth metal water-soluble compound used as a rare-earth metal supply material may include chlorides, nitrates and sulfates of europium, yttrium, cerium, tribium and gadolinium. Examples of the raw material include antimony, manganese, thallium, iron chloride, hydroxide, carbonate, sulfate, and nitrate.

In the method of the present invention, the aluminum alcoholate and the water-soluble compound of the required metal are mixed in an aqueous medium at a ratio corresponding to the constituent atomic ratio of each metal component in the intended high-luminance luminescent material. I do. At this time, the aluminum alcoholate and the water-soluble compound of each metal are dissolved in the aqueous medium so as to have a solid content concentration of 30% by mass or less. As the aqueous medium at this time, water or a mixture of water and a water-miscible solvent such as an alcohol is used.

Next, when the pH of the aqueous solution thus prepared is adjusted to 8.0 or more by adding an alkaline solution, for example, aqueous ammonia, the entire solution becomes gelatinized, that is, becomes sol-gel, and becomes a fine spherical particle. Colloidal particles are formed. The particle shape can be made into a fiber shape, a plate shape, a net shape, etc. other than the spherical shape by adjusting the pH. As the alkali solution at this time, alkali hydroxide, alkali carbonate and the like are also used, but ammonia water is preferred because it can be easily removed by thermal decomposition and the washing step can be omitted.

Next, a dispersion stabilizer is added to the thus obtained colloidal solution, and then the mixture is rapidly dried to obtain spherical gel particle powder having the dispersion stabilizer adhered to the surface. As the above-mentioned dispersion stabilizer, dialkyl carboxylic acid amides such as dimethylformamide, dimethylacetamide and diethylacetamide are preferred, but other compounds effective for gel stabilization can also be used. When the dispersion stabilizer is added, it is preferable to stir vigorously to prevent a crosslinking reaction. Rapid drying is 100-200
The reaction is carried out at a temperature of 0 ° C., if necessary under reduced pressure. This drying is performed using a drying oven set at a temperature equal to or higher than the boiling point of the solvent. In addition, ultrasonic drying, spray drying, or the like may be used.

Next, the dried product thus obtained is calcined in an oxidizing atmosphere, for example, in the air at 500 to 900 ° C., and the resulting solid is crushed lightly to form a reducing atmosphere.
For example, high-brightness light-emitting material powder can be obtained by performing main firing at 1000 to 1700 ° C. in a hydrogen stream. The firing time at this time varies depending on the composition of the material and the firing temperature, but is usually 1 to 6 hours. Further, if necessary, the pulverized preliminarily fired material can be formed into a desired shape prior to the main firing, and thus a luminescent material having an arbitrary shape such as a spherical shape, a plate shape, and a cylindrical shape can be obtained. it can.

In the method of the present invention, when a small amount of boric acid is added to the raw material mixture, a luminescent material with further improved luminance can be obtained. The amount of boric acid added is preferably in the range of 0.01 to 10 mol% based on the total solid content in the aqueous solution.

The high-luminance luminescent material obtained by the method of the present invention is mixed with a polymer to form a sheet, block, sphere,
It can be used after being formed into an arbitrary shape such as a rod shape and a tubular shape. For example, if this is mixed with a copolymer of vinylidene fluoride and tetrafluoroethylene to form a sheet, and electrodes are laminated on both sides, an electroluminescent device can be obtained. The content ratio in the polymer is 10
The range is selected from 70 to 70% by mass, and preferably from 30 to 60% by mass.

[0020]

Next, the present invention will be described in more detail by way of examples.

EXAMPLES Aluminum triisopropoxy Al (O-iC ₃ H ₇ )
₃ 163.4G strontium nitrate Sr (NO _{3) 3} 8
3.8 g and Eu (NO ₃ ) ₃ · 2.9H ₂ O 1.56
g and boric acid H ₃ BO ₃ 1.2 g in water 40 maintained at 40 ° C.
To 0 ml, 18% aqueous ammonia was added with stirring to adjust the pH to 8.5, and the mixture was stirred for 4 hours to prepare a gel solution. Next, 200 ml of dimethylformamide was added thereto, and the mixture was stirred vigorously for 4 hours to mix well, then placed in a drying oven set at 150 ° C., and dried. Next, it is pre-fired at 700 ° C.
After the obtained calcined product was pulverized, it was finally calcined at 1300 ° C. for 4 hours in argon containing 5% by volume of hydrogen. In this way, a high-luminance light-emitting material fine powder having an average particle diameter of 1.5 μm was obtained. FIG. 1 is an XRD pattern showing the crystal structure of the fine powder thus obtained. From this figure, it can be seen that this fine powder contains SrAl ₂ O ₄ of high crystallinity, which does not contain any impurities, as a base substance. As described above, according to the method of the present invention, a highly crystalline product can be obtained despite its small particle size.

Comparative Example A luminescent powder was prepared by the conventional solid-phase method as follows. Aluminum oxide powder, strontium carbonate powder, and europium oxide powder are weighed so that the atomic ratio of Al, Sr, and Eu is 2: 0.99: 0.01, and mixed with 5 mol% of boric acid powder. First, it is calcined at 800 ° C. for 60 minutes in the air, and the obtained calcined product is pulverized.
By firing for 4 hours at an average particle size of 15
A μm luminescent powder was obtained.

Reference Example 1 The luminescent powders obtained in Examples and Comparative Examples were filled in a mold, and
A sample was prepared by press molding at a hydrostatic pressure of GPa, followed by baking at 1500 ° C. for 4 hours. Table 1 shows the emission luminance of these samples when excited by ultraviolet light. For reference, a commercially available product (SrAl ₂ O ₄ .Eu)
The light emission luminance for is also shown.

[0024]

[Table 1]

From this table, it can be seen that the luminescent powder produced by the method of the present invention has small particles and high luminance.

Next, a mechanical action force of 1000 N was applied to these samples by a material testing machine, and the stress luminescence was measured. FIG. 2 shows the relative light emission intensity at that time, and FIG. 3 shows the relative light emission intensity when light was emitted in plasma.

Reference Example 2 The high-luminance light-emitting material powders obtained in Reference Example and Comparative Example were mixed with a powder of a copolymer of vinylidene fluoride and tetrafluoroethylene at a mass ratio of 1: 1. Then, it was formed into a sheet having a thickness of 50 μm. Electrode was formed by depositing Al on one side of this sheet and ITO on the other side to form electrodes. The voltage was applied between both electrodes of the device thus obtained to emit light, and the intensity was measured. The results are shown in FIG. As can be seen from the results of these reference examples, the high-brightness luminescent material manufactured by the method of the present invention exhibits higher luminescence intensity under any of stress excitation, plasma excitation, and electric field excitation as compared with those manufactured by the conventional method. .

[0028]

According to the present invention, a high-luminance luminescent material having a high luminous intensity can be mass-produced by a simple operation, and a particle having a smaller particle diameter than that obtained by the conventional method can be obtained. There is an advantage that it can be uniformly mixed with a synthetic resin or the like.

[Brief description of the drawings]

FIG. 1 is an XRD pattern of one example of a luminescent material obtained by the method of the present invention.

FIG. 2 is a graph showing stress-induced luminescence intensity of luminescent materials obtained by the method of the present invention and the conventional method.

FIG. 3 is a graph showing plasma-excited luminescence intensity of luminescent materials obtained by the method of the present invention and the conventional method.

FIG. 4 is a graph showing electric-field-excited luminescence intensity of luminescent materials obtained by the method of the present invention and the conventional method.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Hiroshi Tateyama 807-1, Nonoshita, Sukumachi, Tosu-shi, Saga Prefecture F-term in Kyushu Industrial Technology Research Institute, National Institute of Advanced Industrial Science and Technology 3K007 AB02 AB18 DA03 DA04 DB00 DC04 FA03 4H001 CA01 CF01 CF02 XA08 XA13 XA20 XA38 XA56 XB21 YA00 YA21 YA25 YA39 YA51 YA58 YA63 YA65

Claims (6)

[Claims] 1. High-intensity light emission comprising at least one kind of aluminate as a base substance and at least one kind of metal ion selected from rare earth metal ions and transition metal ions as a central ion of a light emission center. In producing the material, aluminum alcoholate and at least one water-soluble compound of a component metal other than aluminum are mixed in an aqueous medium, then changed to alkalinity to form a gel, and then a dispersion stabilizer is added thereto. After rapidly drying to produce a dried product having a dispersion stabilizer attached to the surface of the colloidal particles, the dried product is pre-baked at 500 to 900 ° C. in an oxidizing atmosphere,
A method for producing a high-intensity light-emitting material, characterized in that the calcined product is pulverized and the obtained powder is molded or not molded and calcined in a reducing atmosphere at 1000 to 1700 ° C. 2. The method according to claim 1, wherein the component metals are an alkaline earth metal and a rare earth metal or a transition metal. 3. The method according to claim 1, wherein the alkaline earth metal is strontium,
At least one selected from calcium and barium
3. The method according to claim 2, wherein the material is a kind of metal. 4. The method according to claim 2, wherein the rare earth metal or the transition metal is at least one metal selected from europium, yttrium, cerium, tribium, antimony and manganese. 5. The method according to claim 1, wherein the alkaline solution is an aqueous ammonia solution. 6. The method according to claim 1, wherein the dispersion stabilizer is a dialkylcarboxylic acid amide.