JP5844185B2 - Magnesium oxide powder - Google Patents

Description

  The present invention relates to magnesium oxide powder. In particular, the present invention relates to a magnesium oxide powder having the property of generating ultraviolet light when excited with vacuum ultraviolet light.

  It is known that when a specific element is added to the magnesium oxide powder, a property of generating ultraviolet light is exhibited when excited by vacuum ultraviolet light. As the vacuum ultraviolet light, vacuum ultraviolet light having a wavelength of 146 nm (resonance line emission) or 172 nm (molecular beam emission) generated by discharge of Xe (xenon) gas is used.

  In Patent Document 1, magnesium oxide powder in which a Group IIB element of the periodic table, preferably Zn (zinc), is dissolved, has a light emission having a peak in a wavelength range of 260 to 330 nm when excited with an electron beam or ultraviolet light (this The literature describes that this luminescence is called photoluminescence emission). In the example of this document, magnesium oxide powder in which Zn is dissolved is excited by vacuum ultraviolet light having a wavelength of 172 nm. In this document, since the magnesium oxide powder exhibits photoluminescence emission in the ultraviolet region, the discharge rate can be improved by placing it on a protective film or a back plate of a plasma display panel (PDP). There is a description that the driving voltage of the PDP can be reduced.

  Patent Document 2 describes that a fluorine-containing magnesium oxide powder containing F (fluorine) emits ultraviolet light having a peak near a wavelength of 250 nm excited by ultraviolet light generated by discharge of Xe gas. Yes.

  Patent Document 3 discloses ultraviolet light having a peak in the vicinity of a wavelength of 250 nm (230 to 260 nm) in which chlorine-containing magnesium oxide powder containing Cl (chlorine) is excited by ultraviolet light generated by discharge of Xe gas. It is described that it emits light.

JP 2010-126413 A JP 2007-254269 A JP 2008-239475 A

  An object of the present invention is to provide a novel light-emitting material that emits ultraviolet light when excited by vacuum ultraviolet light typified by vacuum ultraviolet light having a wavelength of 172 nm.

  The present inventor has found that magnesium oxide added with Ga (gallium) together with halogen elements such as F and Cl described in Patent Documents 2 and 3 is excited with vacuum ultraviolet light having a wavelength of 172 nm to 270 to 350 nm. The present invention has been completed by finding that it emits ultraviolet light having a peak wavelength in the range of.

  Therefore, this invention exists in the magnesium oxide powder containing a halogen element and Ga.

Preferred embodiments of the magnesium oxide powder of the present invention are as follows.
(1) It has a light emission characteristic that generates ultraviolet light having a light emission peak in a wavelength range of 270 to 350 nm by being excited with vacuum ultraviolet light having a wavelength of 172 nm.
(2) The content of the halogen element is in the range of 0.01 to 0.20 mol when the amount of Mg is 100 mol.
(3) The halogen element is F or Cl.
(4) The Ga content is in the range of 0.001 to 50 mol when the Mg content is 100 mol.
(5) Ga content with respect to halogen element content is in the range of 0.5 to 300 in terms of molar ratio.

The present invention also resides in a luminescent material containing the magnesium oxide powder of the present invention.
The present invention further includes an ultraviolet light emitting layer containing the magnesium oxide powder of the present invention, disposed on the inside of the glass of the fluorescent lamp, and the dielectric protective film or the back plate of the plasma display panel. There is also an ultraviolet light emitting layer containing the magnesium oxide powder of the present invention.

  The present invention is also a method for generating ultraviolet light, characterized by irradiating the magnesium oxide powder of the present invention with vacuum ultraviolet light.

  The magnesium oxide powder of the present invention can be used as a light emitting material that generates ultraviolet light having an emission peak in a wavelength range of 270 to 350 nm when excited by vacuum ultraviolet light. The light emitting material containing the magnesium oxide powder of the present invention is an ultraviolet light of a fluorescent lamp that emits ultraviolet light having an emission peak in a wavelength range of 270 to 350 nm by exciting the light emitting material with vacuum ultraviolet light generated by discharge of Xe gas. It can be used as a light emitting source. Further, as described in the above-mentioned Patent Document 1 (Japanese Patent Laid-Open No. 2010-126413), magnesium oxide showing photoluminescence emission in the ultraviolet region is disposed on the protective film or the back plate of the PDP. The discharge rate can be improved and the driving voltage of the PDP can be reduced. Therefore, by disposing the light emitting layer containing the magnesium oxide powder of the present invention on the protective film or the back plate of the PDP, the discharge rate of the PDP can be improved and the driving voltage can be reduced.

It is sectional drawing of an example of the fluorescent lamp which used the magnesium oxide powder of this invention for the ultraviolet light source. It is sectional drawing of an example of PDP which has arrange | positioned the magnesium oxide powder of this invention on the dielectric material protective film. The fired product No. 1 produced in Example 1 was used. 5 is an emission spectrum obtained by irradiating 5 with vacuum ultraviolet light having a wavelength of 172 nm.

  The magnesium oxide powder of the present invention is a halogen / Ga-containing magnesium oxide powder containing a halogen element and Ga. The halogen / Ga-containing magnesium oxide powder has a light emission characteristic that generates ultraviolet light having an emission peak in a wavelength range of 270 to 350 nm, particularly in a wavelength range of 290 to 310 nm, when excited with vacuum ultraviolet light. This light emission characteristic is considered to be manifested by the presence of the halogen element and Ga in the magnesium oxide crystal. However, it is not necessary that all of the halogen element and Ga are present in the magnesium oxide crystal.

  The halogen element contained in the halogen / Ga-containing magnesium oxide powder is preferably F (fluorine) or Cl (chlorine). The content of the halogen element is preferably in the range of 0.01 to 0.20 mol, particularly preferably in the range of 0.04 to 0.18 mol, when the amount of Mg is 100 mol. The Ga content is preferably in the range of 0.001 to 50 mol, more preferably in the range of 0.01 to 40 mol, particularly preferably 0.03 to 20 as the amount when the amount of Mg is 100 mol. In the molar range. The Ga content (Ga / halogen) relative to the halogen element content is preferably in the range of 0.5 to 300, and particularly preferably in the range of 0.8 to 120, in terms of molar ratio.

Halogen · Ga-containing magnesium oxide powder preferably has BET specific surface area in the range of 0.1 to 5 m ² / g, and particularly preferably in the range of 0.2 to 3 ² / g.

The halogen / Ga-containing magnesium oxide powder can be produced by, for example, a method of mixing a magnesium oxide source powder, a halogen element source powder, and a gallium source powder to obtain a powder mixture, and then firing the powder mixture.
As the magnesium oxide source powder, magnesium oxide powder and magnesium compound powder that generates magnesium oxide powder by heating can be used. Examples of the magnesium compound powder include magnesium hydroxide powder, basic magnesium carbonate powder, magnesium nitrate powder, magnesium oxalate powder, and magnesium acetate powder. It is preferable to use magnesium oxide powder as the magnesium oxide source powder. The magnesium oxide powder is preferably a magnesium oxide powder produced by a gas phase method. The vapor phase method is a method for producing magnesium oxide powder by bringing a metal magnesium vapor and an oxygen-containing gas into contact with each other in the gas phase and oxidizing the metal magnesium vapor.

  Examples of the halogen element source powder include magnesium halide powder, gallium halide powder, and ammonium halide powder. Examples of the gallium source powder include gallium oxide powder, gallium hydroxide powder, gallium carbonate powder, gallium nitrate powder, gallium oxalate powder, and gallium acetate powder.

  The firing of the powder mixture containing the magnesium oxide source powder, the halogen element source powder, and the gallium source powder is preferably performed in an atmosphere shut off from the outside atmosphere, for example, in a heat-resistant container with the lid closed. The firing temperature is preferably in the range of 1000 to 1700 ° C, particularly preferably in the range of 1200 to 1600 ° C. The firing time is generally in the range of 30 minutes or longer, preferably 30 minutes to 10 hours.

The halogen / Ga-containing magnesium oxide powder can also be produced by a method of mixing a magnesium oxide source powder and a gallium source powder to obtain a powder mixture, and then firing the powder mixture in the presence of a halogen-containing gas. it can. Examples of the halogen-containing gas include a hydrogen halide gas, a halogen-containing organic compound gas (CF ₄ , C ₂ F ₆ , C ₃ F _8, etc.) and a gas obtained by heating and vaporizing ammonium halide powder. Can do.

Next, a usage example of the halogen / Ga-containing magnesium oxide powder will be described.
FIG. 1 is a cross-sectional view of an example of a fluorescent lamp using a halogen / Ga-containing magnesium oxide powder as an ultraviolet light source. In FIG. 1, a fluorescent lamp includes a glass tube 1 that is a glass member, a discharge gas filled in an internal space 2 of the glass tube 1, a light emitting layer 3 formed on the inner wall surface of the glass tube 1, and the longitudinal direction of the glass tube 1. And a pair of electrodes 4a and 4b provided at both end portions, and conductive lines 5a and 5b for electrically connecting the electrodes 4a and 4b to an external power source (not shown). As the discharge gas filled in the internal space 2, a mixed gas of rare gas including Xe gas can be used. In the fluorescent lamp of FIG. 1, when a voltage is applied to the electrodes 4a and 4b, the discharge gas filled in the internal space 2 is discharged, and vacuum ultraviolet light represented by a wavelength of 172 nm is generated from Xe. When the halogen / Ga-containing magnesium oxide powder in the light emitting layer 3 is excited by the vacuum ultraviolet light, ultraviolet light having an emission peak in a wavelength range of 270 to 350 nm is generated. This ultraviolet light is emitted outside through the glass tube 1.

  The light emitting layer 3 is formed of a halogen / Ga-containing magnesium oxide powder. The content of the halogen / Ga-containing magnesium oxide powder in the light emitting layer 3 is preferably 80% by mass or more, and more preferably 90% by mass or more. As a method for forming the light emitting layer 3, a dispersion prepared by adding a halogen / Ga-containing magnesium oxide powder and an organic binder to an organic solvent is applied to the glass tube 1 and dried to volatilize the organic solvent. A method of firing can be used.

  FIG. 2 is a cross-sectional view of an example of a PDP in which a halogen / Ga-containing magnesium oxide powder is disposed on a dielectric protective film. In FIG. 2, the PDP (AC type PDP) includes a front plate 10 and a back plate 30 disposed to face each other across a discharge space 20 filled with a discharge gas.

  The front plate 10 includes a transparent substrate 11, a pair of discharge electrodes 14a and 14b formed on the transparent substrate (consisting of transparent electrodes 12a and 12b and bus electrodes 13a and 13b, respectively), and discharge electrodes 14a and 14b. And a dielectric protective film 16 formed on the dielectric layer. On the surface of the dielectric protective film 16, light emitting layers 17 containing halogen / Ga-containing magnesium oxide powder are scattered.

An example of the transparent substrate 11 is a glass substrate. Examples of the transparent electrodes 12a, 12b of the material include ITO, ZnO and SnO _2. Examples of the material of the bus electrodes 13a and 13b include Ag, Al, and a laminated metal material of Cr / Cu / Cr. The dielectric layer 15 is generally formed from a low-melting glass composition. Examples of the low melting point glass composition include a glass composition mainly composed of a mixture of zinc oxide, diboron trioxide and silicon oxide (ZnO—B ₂ O ₃ —SiO ₂ ), lead oxide, diboron trioxide and Glass composition based on silicon oxide mixture (PbO—B ₂ O ₃ —SiO ₂ ), lead oxide, diboron trioxide, silicon oxide and aluminum oxide mixture (PbO—B ₂ O ₃ —SiO ₂ —) Glass composition mainly composed of Al ₂ O ₃ ), glass composition mainly composed of a mixture of lead oxide, zinc oxide, diboron trioxide and silicon oxide (PbO—ZnO—B ₂ O ₃ —SiO ₂ ) Is mentioned. The thickness of the dielectric layer 15 is preferably in the range of 10 to 50 μm. The dielectric protective film 16 is preferably formed from magnesium oxide. The dielectric protective film made of magnesium oxide is preferably formed by electron beam evaporation. The thickness of the dielectric protective film 16 is preferably in the range of 0.01 to 50 μm, and particularly preferably in the range of 0.1 to 10 μm.

  The halogen / Ga-containing magnesium oxide powder forming the light emitting layer 17 may be scattered in the form of primary particles, or may be scattered as aggregated particles (secondary particles). The amount of the halogen / Ga-containing magnesium oxide powder scattered on the surface of the dielectric protective film 16 is such that the area occupied by the halogen / Ga-containing magnesium oxide powder on the surface of the dielectric protective film is the total area of the dielectric protective film. On the other hand, the amount is preferably in the range of 1 to 30%, and more preferably in the range of 5 to 15%. The area occupied by the halogen / Ga-containing magnesium oxide powder can be measured from an enlarged photograph of the dielectric protective film obtained by a scanning electron microscope. As a method for forming the light emitting layer 17, a method in which a dispersion of halogen / Ga-containing magnesium oxide powder is applied on the dielectric protective film and then dried can be used. Examples of the solvent of the dispersion include alcohols such as ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, s-butyl alcohol, and t-butyl alcohol, acetone, ethyl methyl ketone, methyl propyl ketone, and the like. Can be mentioned.

  The discharge space 20 is filled with a discharge gas. As the discharge gas, a mixed gas of Xe and Ne is generally used. The back plate 30 includes a transparent substrate 31, an address electrode 32 formed on the transparent substrate 31, a dielectric layer 33 that covers the address electrode 32, a partition wall 34 that partitions the discharge space 20, and a dielectric layer 33. And a phosphor layer 35 formed on the surface of the partition wall 34. An example of the transparent substrate 31 is a glass substrate. Examples of the material of the address electrode 32 include Ag, Al, and a laminated metal material of Cr / Cu / Cr. The dielectric layer 33 and the partition wall 34 are generally made of a low-melting glass composition. Examples of the low melting point glass composition are the same as those of the dielectric layer 15 described above. The phosphor layer 35 is generally formed of any one of a red light-emitting phosphor, a green light-emitting phosphor, and a blue light-emitting phosphor. A light emitting layer containing a halogen / Ga-containing magnesium oxide powder may be formed on the phosphor layer 35.

[Example 1]
The following raw materials were prepared.
1) Magnesium oxide (MgO) powder A: MgO powder (500A, Ube Materials Co., Ltd.) manufactured by a vapor phase method having a purity of 99.98% by mass and a BET specific surface area of 35.8 m ² / g Made)
B: MgO powder produced by the vapor phase method having a purity of 99.98% by mass and a BET specific surface area of 8.7 m ² / g (2000A, manufactured by Ube Materials Co., Ltd.)
2) Magnesium fluoride (MgF ₂ ) powder with a purity of 99.1% by mass and a BET specific surface area of 6.4 m ² / g 3) Gallium oxide (Ga ₂ O ₃ ) powder With a purity of 99.99% by mass , Having a BET specific surface area of 1.1 m ² / g

The above MgO powder, MgF ₂ powder and Ga ₂ O ₃ powder were mixed at a molar ratio shown in Table 1 below to obtain a powder mixture. The obtained powder mixture is put into an alumina setter having a capacity of 900 mL, the alumina setter is covered and put into an electric furnace, and the furnace temperature is increased to the firing temperature shown in Table 1 below at a heating rate of 240 ° C./hour. And then calcined at that temperature for 180 minutes. Thereafter, the furnace temperature was cooled to room temperature at a temperature lowering rate of 240 ° C./hour. Then, the alumina setter was taken out from the electric furnace, and the fired product No. 1-14 were obtained.

Table 1
────────────────────────────────────────
MgO powder _{MgO: MgF 2: Ga 2 O} 3 types of sintering temperature fired product (molar ratio) (° C.)
────────────────────────────────────────
No. 1 A 100: 0.129: 0.00289 1500
No. 2 B 100: 0.0323: 0.00578 1250
No. 3 B 100: 0.0323: 0.0289 1250
No. 4 A100: 0.0970: 0.0578 1200
No. 5 B 100: 0.0323: 0.145 1200
No. 6 A 100: 0.0841: 1.44 1250
No. 7 A 100: 0.0841: 2.89 1300
No. 8 A 100: 0.0841: 5.78 1250
No. 9 A 100: 0.0970: 7.79 1250
No. 10 A 100: 0.0970: 11.2 1250
No. 11 A 100: 0.0970: 13.0 1250
No. 12 A 100: 0.0970: 16.7 1250
────────────────────────────────────────
No. 13 A 100: 0.0841: 0 1300
No. 14 B 100: 0: 7.00 1200
────────────────────────────────────────

[Evaluation]
Baked product No. About 1-14, Mg content, F content, Ga content, BET specific surface area, and the emission spectrum of this baked product were measured. Table 2 shows the F content and Ga content when the Mg content is 100 mol, the molar ratio of Ga content (Ga / F) to the F content, and the BET specific surface area. Table 3 shows the peak wavelength, maximum emission intensity, and emission intensity at a wavelength of 300 nm read from the emission spectrum. In addition, Mg content, F content, Ga content, and the emission spectrum were measured with the following method.

[Method for measuring Mg content, F content, Ga content]
The fired product of the sample is dissolved with hydrochloric acid, and the contents of Mg, F and Ga in the obtained solution are measured by the method described in 34.1 of JIS-0102 (factory wastewater test method).

[Measurement of emission spectrum]
A fired product of the sample is irradiated with vacuum ultraviolet light having a wavelength of 172 nm, and an emission spectrum emitted from the fired product is measured. In FIG. The emission spectrum of 5 is shown. From the emission spectrum of FIG. 5 shows that the peak wavelength is 295 nm, the maximum emission intensity is 19375, and the emission intensity at a wavelength of 300 nm is 18954.

Table 2
────────────────────────────────────────
F content Ga content Ga / F BET specific surface area Firing product (mol) (mol) (molar ratio) (m ² / g)
────────────────────────────────────────
No. 1 0.194 0.00578 0.030 0.12
No. 2 0.049 0.0116 0.24 0.87
No. 3 0.049 0.0578 1.19 0.63
No. 4 0.146 0.116 0.79 1.58
No. 5 0.049 0.289 5.96 0.90
No. 6 0.126 2.89 22.9 0.62
No. 7 0.126 5.78 45.8 0.73
No. 8 0.126 11.6 91.6 1.10
No. 9 0.146 15.5 106.7 1.30
No. 10 0.146 22.4 153.7 1.71
No. 11 0.146 26.0 178.4 2.01
No. 12 0.146 33.4 229.8 2.20
────────────────────────────────────────
No. 13 0.126 0-1.82
No. 14 0 14.0-4.67
────────────────────────────────────────
Note) F content and Ga content are molar amounts when the Mg content is 100 mol.

Table 3
────────────────────────────────────────
Baked product Peak wavelength (nm) Maximum emission intensity Emission intensity at a wavelength of 300 nm ────────────────────────────────── ──────
No. 1 337 2138 1822
No. 2 331 4466 3201
No. 3 298 10085 10039
No. 4 297 11400 11238
No. 5 295 19375 18954
No. 6 298 19057 19005
No. 7 296 16625 16399
No. 8 299 12488 12474
No. 9 300 11293 11293
No. 10 299 8556 8535
No. 11 299 7506 7488
No. 12 300 6710 6710
────────────────────────────────────────
No. 13 240 6664 1728
No. 14 427 12023 3214
────────────────────────────────────────

  From the results of Tables 2 and 3, the magnesium oxide powder containing F and Ga emits ultraviolet light having an emission peak in the wavelength range of 270 to 350 nm by being excited with vacuum ultraviolet light having a wavelength of 172 nm. It can be seen that it has characteristics. On the other hand, magnesium oxide powder (No. 13) containing only F has an emission peak wavelength of 240 nm, and magnesium oxide powder (No. 14) containing only Ga has an emission peak wavelength of 427 nm.

[Example 2]
Magnesium oxide powder produced by the vapor phase method (purity: 99.98% by mass, BET specific surface area: 8.7 m ² / g, 2000A, manufactured by Ube Materials Co., Ltd.) 1.24 mol and gallium chloride (GaCl ₃ ) 0.0199 mol of powder (purity: 99.9% by mass) was mixed to obtain a powder mixture. The obtained powder mixture is put into an alumina setter having a capacity of 900 mL, the alumina setter is covered and placed in an electric furnace, and the furnace temperature is increased to 1200 ° C. at a temperature rising rate of 240 ° C./hour. Baked for 180 minutes. Thereafter, the furnace temperature was cooled to room temperature at a temperature lowering rate of 240 ° C./hour. And the alumina setter was taken out from the electric furnace, and the baked product was obtained.

  The obtained fired product has a Cl content of 0.0114 mol and a Ga content of 0.405 mol, with a Mg content of 100 mol, and a Ga content relative to the Cl content (Ga / Cl) molar ratio was 35.6. Further, when the fired product was excited with vacuum ultraviolet light having a wavelength of 172 nm, the peak wavelength was 325 nm, the maximum emission intensity was 4782, and the emission intensity at a wavelength of 300 nm was 4394.

DESCRIPTION OF SYMBOLS 1 Glass tube 2 Internal space 3 Light emitting layer 4a, 4b Electrode 5a, 5b Conductive wire 10 Front plate 11 Transparent substrate 12a, 12b Transparent electrode 13a, 13b Bus electrode 14a, 14b Discharge electrode 15 Dielectric layer 16 Dielectric protective film 17 Light emission Layer 20 Discharge space 30 Back plate 31 Transparent substrate 32 Address electrode 33 Dielectric layer 34 Partition 35 Phosphor layer

Claims (8)

A magnesium oxide powder containing a halogen element and Ga, the content of the halogen element being in the range of 0.01 to 0.20 mol when the amount of Mg is 100 mol, and the BET specific surface area is 0.00. Magnesium oxide powder which generates ultraviolet light having an emission peak in a wavelength range of 270 to 350 nm by being excited by excitation light including vacuum ultraviolet light having a wavelength of 172 nm in a range of ^{2 to} 3 m ² / g . The magnesium oxide powder according to claim 1, wherein the emission intensity at 270 nm of the ultraviolet light is smaller than the emission intensity at 300 nm. The magnesium oxide powder according to claim 1 or 2, wherein the halogen element is F or Cl. The magnesium oxide powder according to claim 1 or 2, wherein the Ga content is 0.001 to 50 mol when the amount of Mg is 100 mol. The magnesium oxide powder according to claim 1 or 2, wherein the Ga content with respect to the halogen element content is in a range of 0.5 to 300 in terms of molar ratio . A luminescent material comprising the magnesium oxide powder according to claim 1 . An ultraviolet light emitting layer containing the magnesium oxide powder according to claim 1, which is disposed inside a glass of a fluorescent lamp. A method for generating ultraviolet light, comprising irradiating the magnesium oxide powder according to claim 1 or 2 with vacuum ultraviolet light.

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