JP2004175908A - Blue phosphor for vacuum ultraviolet-exciting light-emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a blue phosphor for vacuum ultraviolet-exciting light-emitting devices slight in luminance drop attributable to heat treatment or plasma exposure. <P>SOLUTION: The phosphor for vacuum ultraviolet-exciting light-emitting devices comprises a compound of the general formula:M<SP>1</SP>M<SP>2</SP>O<SB>3</SB>( wherein, M<SP>1</SP>is at least one atom selected from Ca, Sr and Ba; and M<SP>2</SP>is at least one atom selected from Si and Ge ) and Ln atom(s) as the activator( Ln is at least one atom selected from Pr, Pm, Sm, Eu, b, Dy, Ho, Er, Tm, Yb and Mn ). <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a phosphor suitable for a vacuum ultraviolet ray excited light emitting element such as a plasma display panel (hereinafter referred to as “PDP”) and a rare gas lamp.
[0002]
[Prior art]
Phosphors are used in vacuum ultraviolet ray excited light emitting elements such as PDPs and rare gas lamps, and phosphors that emit light when excited by vacuum ultraviolet rays are already known. For example, a PDP uses a blue phosphor, a green phosphor, and a red phosphor for color display. In the related art, BaMgAl ₁₀ O ₁₇ : Eu has been put to practical use as a blue phosphor. Further, conventionally, Y ₂ SiO ₅ : Ce has been proposed as a blue phosphor (for example, see Non-Patent Document 1).
[0003]
Here, the VUV-excited light-emitting element generates plasma by discharge in a rare gas, and excites the phosphor by irradiating the phosphor disposed in the vicinity of the place where the plasma was generated with vacuum ultraviolet rays emitted from the plasma. Then, the light is emitted by the visible light emitted from the phosphor. As described above, the phosphor is exposed to the plasma, and as a result, the conventional phosphor has a problem that the luminance of the phosphor decreases after the plasma exposure. Further, in the process of manufacturing the VUV-excited light emitting device, there is a step of performing a heat treatment at a temperature range of 300 ° C. to 600 ° C. in order to form a phosphor layer. There was a problem of doing. For this reason, there has been a demand for a phosphor for a vacuum ultraviolet ray excited light emitting device which has a small decrease in luminance due to heat treatment and plasma exposure.
[0004]
[Non-patent document 1]
Phosphors Society of Japan, “Phosphor Handbook”, Ohmsha, p. 332
[0005]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION An object of the present invention is to provide a blue phosphor for a vacuum ultraviolet ray excited light emitting device, in which a decrease in luminance due to heat treatment and plasma exposure is small.
[0006]
[Means for Solving the Problems]
The present inventors have conducted intensive studies on the composition of the phosphor in order to solve the above-mentioned problems, and as a result, have found that a specific silicate and / or germanate containing an alkaline earth metal element and an activator are used. When the phosphor contained was used for a vacuum ultraviolet ray excited light emitting element, it was found that the decrease in luminance due to heat treatment and plasma exposure was small, and the present invention was completed.
[0007]
That is, the present invention relates to a compound represented by the general formula M ¹ M ² O _{3 wherein} M ¹ is at least one member selected from the group consisting of Ca, Sr and Ba, and M ² is one selected from the group consisting of Si and Ge. And Ln as an activator (Ln is selected from the group consisting of Ce, Pr, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, and Mn. And a phosphor for a vacuum ultraviolet ray excited light emitting device.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
The phosphor of the present invention has a general formula of M ¹ M ² O ₃ ... (I)
(Wherein M ¹ is one or more selected from the group consisting of Ca, Sr and Ba, and M ² is one or more selected from the group consisting of Si and Ge). A phosphor containing an active agent. M ¹ is a divalent metal element and is at least one selected from the group consisting of Ca, Sr, and Ba. Wherein M ² in the formula is a tetravalent metal element is one or more selected from the group consisting of Si and Ge.
[0009]
The phosphor of the present invention contains, as an activator, Ln of at least one selected from the group consisting of Ce, Pr, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb and Mn. . Ln is preferably one or more selected from the group consisting of Ce, Eu and Mn, and Eu is more preferable. That is, more preferable the phosphor of the general formula ^{_{(M 1 1-a Eu a}} ) M 2 O 3 ··· (II)
(Wherein M ¹ and M ² have the same meanings as described above). When a is less than 0.001 or more than 0.5, the brightness may be higher when the value is 0.001 or more and 0.5 or less than that when a is more than 0.5.
[0010]
Since M ^{2 in the} general formula (II) is preferably Si, the general formula (M ¹¹ _-b Eu _b ) SiO ₃ (III)
(M ¹ in the formula has the same meaning as described above.). Here, it is preferable that b is in the range of 0.001 or more and 0.5 or less as compared with the case where it is less than 0.001 or more than 0.5 because the luminance of the phosphor of the present invention may be higher.
[0011]
Furthermore, as the ^{M 1} in the general formula (III) Ca: Ba + Sr + Eu = 2: a case 1, the general formula _{(Sr 1-b-c Ba} b Eu c) 1/3 Ca 2/3 SiO 3 ·・ ・ (IV)
(Where b is in the range of 0 or more and 1 or less, c is in the range of 0.003 or more and 0.5 or less, and b + c is less than 1). It is even more preferable because the luminance may be increased by ultraviolet excitation.
[0012]
The phosphor of the present invention can be manufactured as follows, but the manufacturing method is not limited to this. The phosphor of the present invention can be manufactured by firing a mixture of a metal compound which is a phosphor and contains a compound represented by the general formula (I) and Ln as an activator. . That is, it can be manufactured by weighing a compound containing these metal elements so as to have a predetermined composition, mixing, and then firing. For example, a phosphor composed of a compound represented by the composition formula Sr _0.3 Ba _0.68 Eu _0.02 Ca ₂ Si ₃ O ₉ which is one of preferred compositions is SrO, BaO, Eu ₂ O ₃ , CaO , SiO ₂ are weighed so as to have a predetermined composition, mixed, and then fired.
[0013]
Examples of the calcium compound, strontium compound, barium compound, silicon compound, and germanium compound for producing the phosphor of the present invention include high-purity (99% or more) hydroxide, carbonate, nitrate, halide, and oxalic acid. An oxide such as a salt which can be decomposed at a high temperature to become an oxide, or an oxide of high purity (purity of 99% by weight or more) can be used.
[0014]
Compounds containing Ce, Pr, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb and Mn as activators include, for example, those having a high purity (99% by weight or more) of their metal elements. Hydroxides, carbonates, nitrates, halides, oxalates and the like that can be decomposed at high temperatures to become oxides or oxides of high purity (purity of 99% by weight or more) can be used.
[0015]
For the mixing of these raw materials, for example, a device which is usually used in industry, such as a ball mill, a V-type mixer, and a stirrer, can be used.
[0016]
After mixing, for example, the phosphor of the present invention is obtained by firing at a temperature range of 900 to 1500 ° C. for 1 to 100 hours. If the raw materials used are hydroxides, carbonates, nitrates, halides, oxalates, and the like that can be decomposed at high temperatures to become oxides, before the main firing, the temperature range is, for example, 400 ° C. or more and less than 900 ° C. It can be calcined to form an oxide, or water of crystallization can be removed.
[0017]
The firing atmosphere is not particularly limited. For example, firing is preferably performed in a reducing atmosphere such as nitrogen or argon containing 0.1 to 10% by volume of hydrogen. Further, in order to fire in a stronger reducing atmosphere, an appropriate amount of carbon may be added and firing may be performed. The calcining atmosphere may be either an air atmosphere or a reducing atmosphere. Also, an appropriate amount of flux may be added to enhance the crystallinity.
[0018]
Further, the phosphor obtained by the above method can be pulverized using, for example, a ball mill, a jet mill or the like. Further, it can be washed and classified. Further, in order to further improve the luminance of the obtained phosphor, re-firing can be performed.
[0019]
Here, a PDP will be described as an example of a VUV-excited light-emitting display device using the phosphor of the present invention, and a manufacturing method thereof will be described. As a method for producing PDP, for example, a known method disclosed in JP-A-10-195428 can be used. That is, blue, green, each of the phosphor for vacuum ultraviolet excitation light emitting element for red light emission, for example, a cellulose compound, a high molecular compound such as polyvinyl alcohol and a binder made of an organic solvent and mixed with a phosphor paste. Prepare. On the inner surface of the rear substrate of the present invention, a phosphor paste or a phosphor paste is applied to the stripe-shaped substrate surface provided with address electrodes and the partition surface provided with address electrodes by a method such as screen printing. Firing is performed in a temperature range to form each phosphor layer. A surface glass substrate provided with a transparent electrode and a bus electrode in a direction orthogonal to the phosphor layer and provided with a dielectric layer and a protective layer on the inner surface is overlaid and bonded thereto. A PDP can be manufactured by evacuating the inside and filling a low-pressure rare gas such as Xe or Ne to form a discharge space.
[0020]
The phosphor obtained by the present invention emits blue light when excited by, for example, vacuum ultraviolet rays (for example, ultraviolet rays having a wavelength of 200 nm or less such as 146 nm and 172 nm generated by plasma discharge such as Xe), and emits light by heat treatment and plasma exposure. Is suitable for vacuum ultraviolet ray excited light emitting elements such as PDPs and rare gas lamps, and when the phosphor of the present invention is used for vacuum ultraviolet ray excited light emitting elements such as PDPs, the decrease in luminance in the element manufacturing process is small. In addition, it is possible to manufacture an element with less decrease in luminance over time.
[0021]
【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.
[0022]
Comparative Example 1
A commercially available blue phosphor BaMgAl ₁₀ O ₁₇ : Eu was irradiated with vacuum 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., Model H0012). However, blue light was emitted, and the obtained luminance was set to 100. Hereinafter, the luminance of the phosphor when excited by vacuum ultraviolet light having a wavelength of 146 nm is represented by relative luminance, and is represented by adding [146] after the numerical value. Next, the phosphor was heat-treated in the air at 500 ° C. for 30 minutes, and the luminance was measured in the same manner as described above. As a result, the luminance was reduced to 97 [146]. The heated phosphor was placed in an atmosphere having a composition of 5% by volume Xe-95% by volume Ne at a pressure of 13.2 Pa, exposed to 50 W plasma for 15 minutes, and measured for luminance in the same manner as described above. As a result, the luminance decreased to 72 [146].
[0023]
Similarly, a commercially available blue phosphor BaMgAl ₁₀ O ₁₇ : Eu is vacuum ultraviolet light using an excimer 172 nm lamp (Hushio, H0016 type) in a vacuum chamber of 6.7 Pa (5 × 10 ⁻² Torr) or less. Irradiated blue light, and the obtained luminance was set to 100. Hereinafter, the luminance of the phosphor when excited by vacuum ultraviolet light having a wavelength of 172 nm is represented by relative luminance, and is represented by adding [172] after the numerical value. Next, after performing the same heat treatment as above, the luminance was measured in the same manner as above, and as a result, the luminance was reduced to 98 [172]. The heated phosphor was placed in an atmosphere having a composition of 5% by volume Xe-95% by volume Ne at a pressure of 13.2 Pa, exposed to 50 W plasma for 15 minutes, and measured for luminance in the same manner as described above. As a result, the brightness was reduced to 70 [172].
[0024]
Example 1
Strontium carbonate (manufactured by Wako Pure Chemical Industries, Ltd., SrCO ₃ ), barium carbonate (manufactured by Wako Pure Chemical Industries, Ltd.), calcium carbonate (manufactured by Wako Pure Chemical Industries, Ltd.), europium oxide (Shin-Etsu Chemical Co., Ltd.) _Ltd., Eu _{2 O 3),} made of silicon oxide SiO ₂ (Wako pure Chemical (Co.), SiO ₂₎ respective materials _{SrCO 3: BaCO 3: CaCO 3} : Eu 2 O 3: SiO ₂ molar ratio is 0.3 : 0.68: 2: 0.01: 3, mixed and then fired in a ₂ % by volume H ₂ -containing N ₂ atmosphere at a temperature of 1200 ° C for 2 hours. The firing was performed twice. Thus, a phosphor composed of a compound represented by the composition formula Sr _0.3 Ba _0.68 Eu _0.02 Ca ₂ Si ₃ O ₉ was obtained.
[0025]
When this phosphor was irradiated with vacuum ultraviolet rays using an excimer 146 nm lamp (made by Ushio Inc., type H0012) in a vacuum chamber of 6.7 Pa (5 × 10 ⁻² Torr) or less, blue light was emitted. The obtained luminance was set to 100 [146]. Next, the phosphor is heated at 500 ° C. in the atmosphere for 30 minutes, and then placed in an atmosphere having a pressure of 13.2 Pa and a composition of 5% by volume Xe-95% by volume Ne, and exposed to 50 W plasma for 15 minutes. I let it. As a result of taking out the phosphor powder and measuring the emission luminance, the luminance was 98 [146].
[0026]
Similarly, when the phosphor was irradiated with vacuum ultraviolet rays using an excimer 172 nm lamp (Hushio, H0016 type) in a vacuum chamber of 6.7 Pa (5 × 10 ⁻² Torr) or less, strong blue light was emitted. And the obtained luminance was set to 100 [172]. Next, the phosphor is heated at 500 ° C. in the atmosphere for 30 minutes, and then placed in an atmosphere having a pressure of 13.2 Pa and a composition of 5% by volume Xe-95% by volume Ne, and exposed to 50 W plasma for 15 minutes. I let it. As a result of taking out the phosphor powder and measuring the emission luminance, the luminance was 98 [172].
[0027]
【The invention's effect】
The phosphor of the present invention emits blue light when excited by vacuum ultraviolet light or the like, and has a small decrease in luminance due to heat treatment and plasma exposure. Therefore, the phosphor of the present invention is suitable for a vacuum ultraviolet light-emitting element such as a PDP or a rare gas lamp. It is very useful industrially because a vacuum ultraviolet ray excitation light emitting element which has a small luminance decrease in the manufacturing process of the excitation light emitting element and has a high luminance and a small luminance decrease with time can be realized.

Claims (4)

Formula M ¹ M ² O ₃ (wherein M ¹ is one or more selected from the group consisting of Ca, Sr and Ba, and M ² is one or more selected from the group consisting of Si and Ge. ) And Ln as an activator (Ln is at least one selected from the group consisting of Ce, Pr, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb and Mn. A phosphor for a VUV-excited light-emitting device, comprising: Ln is Eu, the general formula _{^{(M 1 1-a Eu a}} ) M 2 O 3 (M 1, M 2 in the formula are as defined above, a is 0.001 to 0.5 The phosphor according to claim 1, comprising a compound represented by the following formula: ^3. The phosphor according to claim 1, wherein M ² is Si. A VUV-excited light-emitting device comprising the phosphor according to claim 1.