JP2004002512A - Method for producing silicate phosphor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a silicate phosphor having high luminance and to provide the phosphor produced by the method for production. <P>SOLUTION: The method for producing the silicate phosphor comprises firing a mixture of metal compounds. In the method, a spherical silicon oxide is used as one of the metal compounds. The silicate phosphor comprises a compound represented by general formula mM<SP>1</SP>O-nM<SP>2</SP>O-2SiO<SB>2</SB>(wherein, M<SP>1</SP>is one or more selected from the group consisting of Ca, Sr and Ba; M<SP>2</SP>is one or more selected from the group consisting of Mg and Zn; m is ≥0.5 and ≤3.5; and n is ≥0.5 and ≤2.5) and one or more selected from the group consisting of Eu and Mn as an activator. The silicate phosphor is obtained by the method for production described in any thereof and contains ≥80 wt.% of particles having ≤5 μm primary particle diameter. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing a silicate phosphor, and more particularly to a method for producing a silicate phosphor suitable for a vacuum ultraviolet ray excited light emitting device such as a plasma display panel (PDP) and a rare gas lamp.
[0002]
[Prior art]
Silicate phosphors are used in fluorescent lamps, cathode ray tubes, luminous bodies, VUV-excited light emitting devices, and the like. Particularly, in a vacuum ultraviolet ray excited light emitting device such as a PDP, it is strongly desired to improve the brightness of the device, and the brightness of a silicate phosphor used for them is required.
[0003]
Silicate phosphors have been conventionally produced by firing a mixture of metal compounds. Silicon oxide is used as a metal compound serving as a silicon source. In a conventional production method, an amorphous material having an irregular particle shape has been used because it is industrially easily available and inexpensive.
[0004]
[Problems to be solved by the invention]
An object of the present invention is to provide a method for producing a silicate phosphor having high luminance and a phosphor produced by the method.
[0005]
[Means for Solving the Problems]
The present inventors have conducted intensive studies under such circumstances, and as a result, in a method for producing a silicate phosphor by firing a mixture of metal compounds, a spherical silicon oxide was used as a raw material silicon oxide as a metal oxide. When used as one, they found that a silicate phosphor with high light emission luminance could be manufactured, and completed the present invention.
[0006]
That is, the present invention provides a method for producing a silicate phosphor by firing a mixture of metal compounds, wherein spherical silicon oxide is used as one of the metal compounds. The present invention also provides the above-mentioned production method, wherein the ratio of the major axis / minor axis of the spherical silicon oxide is 1 or more and 1.5 or less. Further, the present invention provides the production method according to any one of the above, wherein the spherical silicon oxide has an average particle diameter of 0.1 μm or more and 3 μm or less. Further, the present invention provides the method according to any one of the above, wherein the spherical silicon oxide has a BET specific surface area of 1 m ² / g or more and 30 m ² / g or less. Further, in the present invention, the mixture of metal compounds is a mixture of a compound of one or more metal elements selected from the group consisting of Ca, Sr, Ba, Mg, Eu, Mn and Zn and a compound of Si. And a method for producing the same. Further, the present invention provides the production method according to any one of the above, wherein the highest attained temperature in the firing is in a temperature range of 1000 ° C. or more and 1400 ° C. or less. In the present invention, the silicate phosphor preferably has a general formula of mM ¹ O · nM ² O · 2SiO ₂ (wherein M ¹ is at least one member selected from the group consisting of Ca, Sr and Ba, and M ² is Mg And m is at least 0.5 and at most 3.5, and n is at least 0.5 and at most 2.5, and Eu as an activator. The method according to any one of the above, which is a silicate phosphor containing at least one member selected from the group consisting of Mn. The present invention also provides a silicate phosphor obtained by any one of the production methods described above. Further, the present invention provides the silicate phosphor described above, wherein the particles having a primary particle diameter of 5 μm or less are contained in an amount of 80% by weight or more.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
The method for producing a silicate phosphor according to the present invention is a method for producing a silicate phosphor, wherein the mixture is a mixture of metal compounds and is capable of forming a silicate phosphor by firing. , A spherical silicon oxide is used. The metal compound also includes a compound of a metal element which is an activator. In the production method of the present invention, silicon oxide is a powder composed of spherical particles. By using spherical silicon oxide, a phosphor with high brightness can be obtained, although the reason is not clear.
[0008]
Here, as the particles of silicon oxide, when measured using an electron micrograph, the largest one of the diameters of one primary particle is the longer diameter, and the smallest one is the shorter diameter. The ratio is preferably 1.5 or less, more preferably 1.3 or less. If the silicon oxide particles are perfect spheres, the ratio of the major axis to the minor axis is 1. The average particle size of the silicon oxide is preferably from 0.1 μm to 3 μm, more preferably from 0.2 μm to 2 μm, even more preferably from 0.2 μm to 1.7 μm. The BET specific surface area of the spherical silicon oxide is preferably from 1 m ² / g to 30 m ² / g, more preferably from 2 m ² / g to 20 m ² / g. When the ratio of the major axis / minor axis of the spherical silicon oxide exceeds 1.5, when the average particle diameter is less than 0.1 μm or more than 3 μm, and when the BET specific surface area is less than 1 m ² / g or more than 30 m ² / g, High brightness may not be obtained.
[0009]
In the production method of the present invention, the metal compound contained in the mixture capable of constituting the silicate phosphor by firing with the mixture of the metal compounds, and the compound other than silicon oxide includes hydroxide, carbonate, and nitrate of the metal element. , Halides, oxalates, etc., compounds or oxides that become oxides at high temperatures can be used, and these metal compounds can be conventional compounds.
[0010]
Next, the mixture of metal compounds in the production method of the present invention can be obtained by mixing the respective metal compounds by a mixing method generally used industrially. As a method of mixing, either a dry method or a wet method may be used. When dry mixing is performed, an apparatus such as a ball mill, a V-type mixer, or a stirrer can be used as an apparatus used for mixing. Water and an organic solvent can be added and wet mixing can be performed using a ball mill or a stirrer.
[0011]
When wet mixing is performed, the mixture is dried directly, or dried after separating a solid from a liquid by a method such as filtration or centrifugation. The drying temperature is preferably in the range of 20 to 300 ° C, more preferably 90 to 200 ° C. Examples of the method for directly drying include evaporation and spray drying for drying while granulating.
[0012]
Next, in firing the mixture of metal compounds, the highest temperature is preferably in a temperature range of 1000 ° C. to 1400 ° C. In the firing, the time for maintaining the temperature in the range of 1000 ° C. to 1400 ° C. is preferably 0.5 to 50 hours. In firing, for example, the raw material can be filled in an alumina boat and fired at a predetermined temperature in a predetermined gas atmosphere. If necessary, a silicate phosphor having better crystallinity and higher luminance may be obtained by mixing a reaction accelerator (flux) such as boron oxide or aluminum fluoride with the raw material.
[0013]
In the mixture of the metal compounds, hydroxides, carbonates, nitrates, halides, oxalates, and the like of the metal elements, when those that can be decomposed at high temperatures to become oxides are contained, before the calcination, It is also possible to perform calcination in a temperature range of 400 ° C. to 900 ° C.
[0014]
The phosphor obtained by the above method can be pulverized using a ball mill, a jet mill, or the like, washed with water or the like, and classified if necessary. In order to increase the crystallinity of the obtained phosphor, re-firing can be performed as necessary. The agglomerated state of the primary particles of the silicate phosphor obtained by the present invention is weaker than the case where only a conventional silicon compound which is not spherical silicon oxide is used, and the subsequent steps such as pulverization can be simplified.
[0015]
The production method of the present invention can be preferably applied when the metal compound is a compound of one or more metal elements selected from the group consisting of Ca, Sr, Ba, Mg, Eu, Mn, and Zn and a compound of Si, As the silicate phosphor in the production method of the present invention, as the silicate phosphor, a compound represented by the general formula: mM ¹ O · nM ² O · 2SiO ₂ (where M ¹ is at least one member selected from the group consisting of Ca, Sr and Ba, M ² Is one or more selected from the group consisting of Mg and Zn, m is 0.5 or more and 3.5 or less, and n is 0.5 or more and 2.5 or less.) And an activator A silicate phosphor containing at least one selected from the group consisting of Eu and Mn is preferable. In any of the cases where m is less than 0.5, m is greater than 3.5, n is less than 0.5, and n is greater than 2.5, a high-luminance silicate fluorescence is used. It may not be a body.
[0016]
For example, when producing CaMgSi ₂ O ₆ : Eu which is a blue phosphor, a compound of Ca, Mg, and Eu, which can constitute CaMgSi ₂ O ₆ : Eu by firing, and spherical silicon oxide are used as raw materials. And a compound of Si other than silicon oxide may be added.
[0017]
Next, these metal compounds are weighed, mixed and fired so as to become a phosphor composed of the compound represented by the composition formula CaMgSi ₂ O ₆ : Eu. The firing can be performed one or more times in a reducing atmosphere at a temperature in the range of 1000 ° C. to 1400 ° C. for 0.5 to 40 hours. As a method for obtaining a reducing atmosphere, there is a method of firing in a mixed atmosphere of nitrogen and hydrogen or a rare gas and hydrogen. Further, water vapor may be contained in these atmospheres. In addition, after firing in the temperature range of 1000 ° C. or higher and 1400 ° C. or lower, firing can be performed again in a reducing atmosphere at a temperature range of 1000 ° C. or higher and 1400 ° C. or lower.
[0018]
The silicate phosphor obtained by the production method of the present invention as described above has high luminance under vacuum ultraviolet excitation, and thus is suitable for vacuum ultraviolet excitation light emitting devices such as PDPs and rare gas lamps. Further, the silicate phosphor obtained by the production method of the present invention exhibits high luminance not only in vacuum ultraviolet rays but also in excitation by ultraviolet rays, cathode rays or X-rays.
[0019]
【Example】
Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
[0020]
Example 1
Using spherical silicon oxide (SiO ₂ , manufactured by Admatechs Co., Ltd.) having an average particle diameter of 0.3 μm, a BET specific surface area of 15.5 m ² / g, and a major axis / minor axis ratio of 1.0, calcium carbonate ( CaCO ₃ , strontium carbonate (manufactured by Wako Pure Chemical Industries, Ltd.) SrCO ₃ , europium oxide (manufactured by Shin-Etsu Chemical Co., Ltd.) Eu ₂ O ₃ , basic magnesium carbonate (MgCO ₃ ) ₄ Mg _(OH) 2 · _5H 2 O each raw materials CaCO of (manufactured by Wako Pure Chemical Industries, _{Ltd.) 3: SrCO 3: Eu 2} O 3: (MgCO 3) 4 Mg (OH) 2 · 5H 2 O: of SiO ₂ After blending and mixing so that the molar ratio becomes 0.855: 0.095: 0.025: 0.2: 2, the mixture is kept at a temperature of 1200 ° C. for 2 hours in an Ar atmosphere containing 2% by volume of H _2. Firing . Thus, a phosphor composed of the compound represented by the composition formula Ca _0.855 Sr _0.095 Eu _0.05 MgSi ₂ O ₆ was obtained. The primary particle size of the obtained phosphor was measured using a photograph of the phosphor particles with a scanning electron microscope, and as a result, all were 5 μm or less. When this phosphor was irradiated with ultraviolet rays in a vacuum chamber of 6.7 Pa (5 × 10 ⁻² Torr) or less using an excimer 146 nm lamp (Hushio Electric Co., Ltd., H0012 type), the luminance of Comparative Example 1 was reduced. Assuming 100, the luminance was 140.
[0021]
Example 2
Example 1 except that spherical silicon oxide (SiO ₂ , manufactured by Admatechs Co., Ltd.) having an average particle diameter of 0.6 μm, a BET specific surface area of 5.2 m ² / g, and a major axis / minor axis ratio of 1.0 was used. A phosphor was produced in the same manner as in Example 1. When this phosphor was irradiated with ultraviolet rays in a vacuum chamber of 6.7 Pa (5 × 10 ⁻² Torr) or less using an excimer 146 nm lamp (Hushio Electric Co., Ltd., type H0012), the luminance of Comparative Example 1 was reduced. Assuming 100, the luminance was 145.
[0022]
Example 3
Example 1 except that spherical silicon oxide (SiO ₂ , manufactured by Admatechs Co., Ltd.) having an average particle diameter of 0.9 μm, a BET specific surface area of 3.3 m ² / g, and a major axis / minor axis ratio of 1.0 was used. A phosphor was produced in the same manner as in Example 1. When this phosphor was irradiated with ultraviolet rays in a vacuum chamber of 6.7 Pa (5 × 10 ⁻² Torr) or less using an excimer 146 nm lamp (Hushio Electric Co., Ltd., type H0012), the luminance of Comparative Example 1 was reduced. Assuming 100, the luminance was 135.
[0023]
Example 4
Example 1 except that spherical silicon oxide (SiO ₂ , manufactured by Admatechs Co., Ltd.) having an average particle size of 1.5 μm, a BET specific surface area of 3.8 m ² / g, and a major axis / minor axis ratio of 1.0 was used. A phosphor was produced in the same manner as in Example 1. When this phosphor was irradiated with ultraviolet rays in a vacuum chamber of 6.7 Pa (5 × 10 ⁻² Torr) or less using an excimer 146 nm lamp (Hushio Electric Co., Ltd., type H0012), the luminance of Comparative Example 1 was reduced. Assuming 100, the luminance was 125.
[0024]
Comparative Example 1
A phosphor was prepared in the same manner as in Example 1 except that amorphous silicon oxide having a crushed surface (SiO ₂ , manufactured by Wako Pure Chemical Industries, Ltd., catalog number 199-06125) was used. As a result of measuring the luminance in the same manner as in Example 1, the luminance was 100.
[0025]
【The invention's effect】
According to the present invention, a silicate phosphor having high luminance can be provided. Since the silicate phosphor has high luminance when excited by vacuum ultraviolet light, it is a suitable phosphor for vacuum ultraviolet light-emitting devices such as PDPs and rare gas lamps, and the production method of the present invention is industrially extremely useful.

Claims (9)

A method for producing a silicate phosphor by firing a mixture of metal compounds, wherein spherical silicon oxide is used as one of the metal compounds. The production method according to claim 1, wherein the ratio of the major axis / minor axis of the spherical silicon oxide is 1 or more and 1.5 or less. 3. The production method according to claim 1, wherein the spherical silicon oxide has an average particle size of 0.1 μm or more and 3 μm or less. The process according to any one of claims 1 to 3 BET specific surface area of the silicon oxide spherical is not more than ^{1 m} 2 / g or more ^{30 m} 2 / g. The mixture of metal compounds is a mixture of a compound of one or more metal elements selected from the group consisting of Ca, Sr, Ba, Mg, Eu, Mn and Zn and a compound of Si. Manufacturing method. The production method according to any one of claims 1 to 5, wherein a maximum attained temperature in the firing is in a temperature range of 1000C to 1400C. The silicate phosphor has a general formula of mM ¹ O · nM ² O · 2SiO ₂ (wherein M ¹ is at least one member selected from the group consisting of Ca, Sr and Ba, and M ² is a group consisting of Mg and Zn) M is 0.5 or more and 3.5 or less, and n is 0.5 or more and 2.5 or less), and Eu and Mn as activators. The production method according to any one of claims 1 to 6, which is a silicate phosphor containing at least one selected from the group consisting of: A silicate phosphor obtained by the production method according to claim 1. The silicate phosphor according to claim 8, wherein particles having a primary particle diameter of 5 µm or less are contained in an amount of 80% by weight or more.