JP2006273929A - Fluorescent substance for electron beam excitation and electron beam excitation fluorescence emission element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluorescent substance for electron beam excitation, having an excellent luminance lifetime, and to provide an electron beam excitation fluorescence emission element given by using the same. <P>SOLUTION: This fluorescent substance for the electron beam excitation comprises a crystal having a β-type silicon nitride crystal structure and composed of elements of Eu, Si, Al, O, and N and is expressed by composition formula: Eu<SB>a</SB>Si<SB>b</SB>Al<SB>c</SB>O<SB>d</SB>N<SB>e</SB>[a+b+c+d+e=1; and a, b, c, d and e satisfy conditions (1) to (5) as follows: (1) 0.00001≤a≤0.1; (2) 0.28≤b≤0.46; (3) 0.001≤c≤0.3; (4) 0.001≤d≤0.3; and (5) 0.4≤e≤0.62]. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a phosphor that emits light by the impact of an electron beam and a fluorescent light emitting device using the phosphor, and the driving voltage of an electron beam excitation phosphor excellent in luminance life and an anode on which the phosphor is applied is 0. The present invention relates to an electron beam-excited fluorescent light emitting device of 1 kV or higher.

  Conventionally, a display device using a field emission cathode as an electron source (Field Emission Display, hereinafter abbreviated as “FED”) and a fluorescent display device using a thermionic emission cathode (hereinafter referred to as “VFD”) are abbreviated as “VFD”. In order to obtain each emission color, phosphors composed of various fluorescent light emitting elements are used. And as a green light emission fluorescent substance for display apparatuses by electron beam excitation, what is indicated by patent documents 1 or patent documents 2, for example is publicly known.

Patent Document 1, A ₂ SiO _5: B phosphor composition elemental ratio in the surface at body (A + B) / Si is A ₂ SiO ₅ emitting green light is 1.5 to 2.5: B phosphor (where A is Y or Gd, B is Ce or Tb) and its production method is disclosed. Patent Document 2 discloses a phosphor powder of ZnS: Cu, Al, ZnS: Cu, Au, Al as a phosphor emitting green light different from the composition of Patent Document 1.

On the other hand, conventional phosphors are irradiated with an excitation source such as light or electron beam having high energy, and are excited to emit light. As a result, there is a problem that the luminance of the phosphor is lowered. Therefore, there is a demand for a phosphor that does not have a decrease in luminance.
In order to provide a phosphor capable of meeting such a demand, for example, an α-comprising Ca, Eu, Si, Al, O, and N elements as disclosed in Patent Document 3, each of which has a specific composition region range. Phosphors containing sialon have been proposed.

Non-Patent Document 1 discloses β-type Si ₃ N ₄ , β-type sialon, and the like. These have been conventionally studied as heat-resistant materials, and they describe that an optically active element is dissolved in the present crystal and that the dissolved solution is used as a phosphor. As nitrides or oxynitrides having this crystal structure, β-type Si ₃ N ₄ , β-type Ge ₃ N ₄ and β-type sialon (Si _6-z Al _z O _z N _8-z , where 0 ≦ z ≦ 4.2) and the like, and the β-type Si ₃ N ₄ crystal structure is defined as a structure having symmetry of P6 ₃ or P6 ₃ / m and having an ideal atomic position. Further, it is known that at a synthesis temperature of 1700 ° C. or lower, metal elements do not dissolve in the crystal, and the metal oxide added as a sintering aid or the like forms a glass phase at the grain boundary and remains. .

Further, according to Patent Document 4, a phosphor having Tb, Yb, and Ag added as a phosphor having an emission peak at a wavelength in the range of 500 nm to 550 nm by applying ultraviolet rays is reported.
JP 2001-271065 A Japanese Patent Laid-Open No. 2002-265942 JP 2005-8793 A JP-A-60-206889 CHONG-MIN WANG and 4 others “Journal of Materials Science” 1996, 31 volumes, 5281-5298 pages

However, the Y ₂ SiO _5: Tb phosphor disclosed in Patent Document 1 has a significant decrease in light emission efficiency in the lifetime characteristics, and the FED has an extreme difference in the degree of degradation of the RGB phosphor. There was a problem that the color balance shifted. In addition, it is difficult to use a metal back for an FED having a driving voltage of about 3 kV because of the penetration depth of electrons. Furthermore, the phosphor containing ZnS: Cu, Al or the like disclosed in Patent Document 2 has an emission capability that is reduced because sulfur is scattered by electron impact and contaminates the electron source, and the lifetime of the device is reduced. There are problems that make it worse.

  In addition, in the technology relating to the sialon phosphor disclosed in Patent Document 3 or Non-Patent Document 1, there is no specific disclosure regarding a fluorescent display tube such as a field emission device.

  Further, the phosphor added with Tb disclosed in Patent Document 4 contains various wavelength components, so it is not suitable as a green phosphor for a display or a fluorescent display tube, and an afterimage remains because of its long emission lifetime. It is difficult to fit. And the thing which added Yb and Ag also had the problem that a brightness | luminance was low.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide an electron beam excitation phosphor and an electron beam excitation fluorescent light-emitting element that have a low degree of deterioration and do not shift in color balance with the lifetime. Is.

  To achieve the above object, the phosphor for electron beam excitation according to claim 1 has a β-type silicon nitride crystal structure that emits fluorescence having a peak at a wavelength between 500 nm and 550 nm when irradiated with an electron beam. It contains a β-type sialon crystal in which Eu is dissolved.

The phosphor for electron beam excitation according to claim 2 is represented by the composition formula Eu _a Si _b Al _c O _d Ne (where a + b + c + d + e = 1) in the phosphor for electron beam excitation according to claim 1. A, b, c, d, e in the formula
0.00001 ≦ a ≦ 0.01
0.28 ≦ b ≦ 0.46
0.001 ≦ c ≦ 0.3
0.001 ≦ d ≦ 0.3
0.4 ≦ e ≦ 0.62
It contains a β-type sialon crystal that satisfies the following conditions.

  The electron beam excited fluorescent light emitting device according to claim 3 is characterized in that the electron beam excited phosphor according to claim 1 or 2 is used.

  The electron beam excited fluorescent light emitting device according to claim 4 is the electron beam excited fluorescent light emitting device according to claim 3, wherein the electron beam excited fluorescent light emitting device is an electroluminescent device.

  The electron beam excited fluorescent light emitting device according to claim 5 is the electron beam excited fluorescent light emitting device according to claim 3, wherein the electron beam excited fluorescent light emitting device is a fluorescent display tube.

  According to the electron beam excitation phosphor and the electron beam excitation fluorescent light emitting device of the present invention, it is possible to provide a green electron beam excitation phosphor that has a low degree of deterioration at a driving voltage of 0.1 kV or more and has an excellent luminance life. In addition, when used in an electron beam-excited fluorescent light-emitting element used in a display device such as an FED or VFD, the luminance life is excellent, so that an effect of suppressing a shift in RGB color balance is achieved.

  Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings. FIG. 1 is a graph comparing the anode voltage-anode current of an electron beam excited fluorescent light emitting device using the phosphor for electron beam excitation of the present invention and a conventional fluorescent light emitting device, and FIG. FIG. 3 is a graph comparing the emission efficiency of the conventional display element, FIG. 3 is a graph comparing the emission capabilities of the electron beam excited fluorescent light emitting element and the conventional display element, and FIG. 4 is a graph comparing the electron beam excited fluorescent light emitting element and the conventional display element. FIG. 5 is a cross-sectional view of a general FED, and FIG. 5 is a chart showing the amount of change in chromaticity with the display element.

The phosphor for electron beam excitation of the present invention is a crystal having a β-type silicon nitride crystal structure, and includes a β-type sialon crystal in which Eu is dissolved as a main component. The β-type silicon nitride crystal structure can be identified by X-ray diffraction and neutron diffraction, and in addition to substances exhibiting the same diffraction as pure β-type Si ₃ N ₄ , constituent elements are replaced with other elements. Those whose lattice constants are changed by the above are also β-type silicon nitride crystal structures. β-sialon is a structure in which part of Si in β-Si ₃ N ₄ crystal is Al and part of N is replaced by O. Generally, β-type silicon nitride contains Si, Al, O, and N. A crystal having a crystal structure.

  The inventors of the present invention have found that the field emission element has an anode voltage set to several hundred volts to several kV, and as a result of experimental research using various phosphor samples, it is decomposed by high-voltage electron impact. It was found that sialon phosphors are promising as green light-emitting phosphors for field emission devices because they are difficult to scatter, and further research on green light-emitting phosphors revealed that β-type silicon nitride crystal structures were used as phosphors. A novel idea of adopting a phosphor containing β-sialon crystal in which Eu is dissolved is obtained.

In the present invention, the type of composition is not particularly limited as long as it has a β-type Si ₃ N ₄ crystal structure and contains elements of Eu, Si, Al, O, and N, but the β-type sialon has the following composition: A green phosphor having a high content ratio and high luminance is obtained. The composition formula is represented by Eu _a Si _b Al _c O _{d Ne} (where a + b + c + d + e = 1), and a, b, c, d, and e satisfy the following conditions (1) to (5): It is appropriately selected from values that satisfy all.
(1): 0.00001 ≦ a ≦ 0.1
(2): 0.28 ≦ b ≦ 0.46
(3): 0.001 ≦ c ≦ 0.3
(4): 0.001 ≦ d ≦ 0.3
(5): 0.4 ≦ e ≦ 0.62

  In the composition formula, a represents the amount of addition of the element Eu serving as the emission center. If the a value is smaller than 0.00001, the number of Eus that are the emission center is small, and the emission luminance is lowered. On the other hand, if the ratio is larger than 0.1, concentration quenching occurs due to interference between Eu ions, and the luminance decreases. The atomic ratio is preferably 0.00001 ≦ a ≦ 0.1.

In the composition formula, b is the amount of Si, and it is preferable that the atomic ratio is 0.28 ≦ b ≦ 0.46. Further, c in the composition formula is the amount of Al, and it is preferable that the atomic ratio is 0.001 ≦ c ≦ 0.3.
The total value of b and c is preferably 0.41 ≦ b + c ≦ 0.44, particularly preferably 0.429. When the b and c values are out of this range, the generation rate of the crystal phase other than β-sialon increases and the green emission intensity decreases.

In the composition formula, d is the amount of oxygen, and it is preferable that the atomic ratio is 0.001 ≦ d ≦ 0.3. Further, e in the composition formula is the amount of nitrogen, and it is preferable that the atomic ratio is 0.54 ≦ e ≦ 0.62.
The total value of d and e is preferably 0.56 ≦ d + e ≦ 0.59, particularly preferably 0.571. When the d and e values are out of this range, the generation ratio of the crystal phase other than β-sialon increases, and the green emission intensity decreases.

  Next, an example of the composition and manufacturing method of the β-type sialon phosphor will be described. In addition, the manufacturing method shown below is an example and is not limited to this.

  The raw material powder is silicon nitride powder having an average particle size of 0.5 μm, oxygen content of 0.93% by weight, α-type content of 92%, aluminum nitride powder having a specific surface area of 3.3 m 2 / g and oxygen content of 0.79%. Europium oxide powder having a purity of 99.9% was used.

In order to obtain a compound represented by the composition formula Eu _0.00296 Si _0.41395 Al _0.01334 O _0.00444 N _0.56528 , silicon nitride powder, aluminum nitride powder and europium oxide powder were respectively 94.77 wt%, 2.68 wt% and 2.556 wt%. It weighed so that it might become weight%, and mixed for 2 hours with the wet ball mill using the pot made from a silicon nitride sintered compact, the ball made from a silicon nitride sintered compact, and n-hexane.

  N-Hexane was removed by a rotary evaporator to obtain a dry product of the mixed powder. The obtained mixture was pulverized using an agate mortar and pestle and then passed through a 500 μm sieve to obtain a powder aggregate having excellent fluidity. The powder agglomerate was naturally dropped into a boron nitride crucible having a diameter of 60 mm and a height of 35 mm, and a sample was charged.

  Next, the crucible was set in a graphite resistance heating type electric furnace. In the firing operation, first, the firing atmosphere is evacuated by a diffusion pump, heated from room temperature to 800 ° C. at a rate of 500 ° C. per hour, introduced with nitrogen having a purity of 99.999% by volume at 800 ° C. and a pressure of 1 MPa, The temperature was raised to 2000 ° C. at 500 ° C. per hour and held at 2000 ° C. for 8 hours.

  The synthesized sample was pulverized into powder using an agate mortar, and powder X-ray diffraction measurement (XRD) using Cu Kα rays was performed. As a result, the obtained chart had a β-type silicon nitride structure.

  Using the β-sialon phosphor thus produced, CL (cathode luminescence) evaluation by VFD was performed.

As shown in FIG. 1, a phosphor was formed on an anode electrode using a paste obtained by mixing β-sialon phosphor in an organic solvent in which ethyl cellulose was dissolved in butyl carbitol, and VFD was produced and evaluated. Only when the voltage was applied to about 250 V or more, current flowed through the anode, and light emission was confirmed (A line in the figure). For comparison, the Y ₂ SiO ₅ : Tb phosphor was evaluated in the same manner. As a result, a current flowed through the anode at an anode voltage of about 80 V, and light emission was confirmed (B line in the figure). Therefore, when β-sialon phosphor was mixed with ZnO as a conductive agent in an amount of 5 wt% with respect to the phosphor, the anode current flow-out voltage was reduced to about 10 V, and light emission was confirmed (C line in the figure). ).

Next, a phosphor using a β-sialon phosphor, an organic solvent in which 5 wt% of ZnO as a conductive agent is mixed in the phosphor and ethyl cellulose is dissolved in butyl carbitol, and a phosphor paste mixed therein is used as an anode. An FED was formed and evaluated on an electrode. The drive conditions were an acceleration voltage of 3 kV, a pulse drive with a duty of 1/240, and a current density of 8 mA / cm ² .

FIG. 2 shows the half-life of the luminous efficiency under the above driving conditions as a relative ratio. Comparative Example 1 was a fluorescent light emitting device using a Y ₂ SiO ₅ : Tb phosphor, Comparative Example 2 was a ZnS: Cu, Al phosphor, and Y ₂ SiO ₅ : Tb phosphor was a standard of 1.0. As shown in FIG. 2, the comparative example 1 was 1.0 and the comparative example 2 was 3.0, whereas the present example was about 5.5. As a result, this example shows that the luminous efficiency is improved by about 5.5 times compared to Comparative Example 1 and about 1.83 times compared to Comparative Example 2.

FIG. 3 shows the half-life of emission capability as a relative ratio under the same driving conditions. Comparative Example 1 is a fluorescent light emitting device using a Y ₂ SiO ₅ : Tb phosphor, Comparative Example 2 is a fluorescent light emitting device using a ZnS: Cu, Al phosphor, and Y ₂ SiO ₅ : Tb phosphor is 1.0. The standard of As shown in FIG. 3, the comparative example 1 was 1.0 and the comparative example 2 was 0.21, whereas the fluorescent light emitting device of this example was about 1.22. As a result, this example shows that the emission capability is improved by about 1.22 times compared to Comparative Example 1 and about 6.0 times compared with Comparative Example 2.

FIG. 4 shows the amount of change in chromaticity after 2000 hours of life test in full lighting of the FED. The fluorescent light-emitting device of this example was compared with the fluorescent light-emitting device using the Y ₂ SiO ₅ : Tb phosphor of Comparative Example 1 and the fluorescent light-emitting device using the ZnS: Cu, Al phosphor of Comparative Example 2, It can be seen that there is little change in degree and that the life stability is excellent.

  Hereinafter, the present invention will be described in more detail with reference to examples. It should be noted that each of the following embodiments is not of a nature that limits the present invention, and any design changes that fall within the spirit of the preceding and following descriptions are within the technical scope of the present invention.

Example 1
FIG. 5 shows a general configuration FED. An envelope having an anode substrate 1 and a cathode substrate 2 facing each other and sealed around the periphery is provided. A field emission cathode 3 (FEC) that is an electron source is formed on the inner surface of the cathode substrate 2, and an anode 4 that is a light emitting portion is formed on the inner surface of the anode substrate 1 facing the cathode substrate 2. The FEC 3 includes a cathode conductor 5 formed on the cathode substrate 2, an insulating layer 6 formed thereon, a gate 7 formed thereon, a hole 8 formed in the insulating layer 6 and the gate 7, It has a cone-shaped emitter 9 formed on the cathode conductor 5 in the hole 8. The anode 4 is composed of a transparent conductive film 10 such as ITO formed as an anode conductor on the anode substrate 1 and a phosphor layer 11 formed thereon. The electrons emitted from the FEC 3 strike the phosphor layer 11 of the anode 4 to emit light. The light emission of the phosphor layer 11 is observed from the outside of the anode substrate 1 through the translucent transparent conductive film 10 and the anode substrate 1.

Then, 5 wt% of ZnO fine particles having an average particle diameter of 0.5 μm as a conductive agent are mixed in the FED having the above-described configuration with the phosphor emitting green light represented by the β-type sialon phosphor described above, from ethyl cellulose and butyl carbitol. A life-cycle characteristic was evaluated by mounting a phosphor paste dispersed in a solvent as a paste. For comparison, Y ₂ SiO ₅ : Tb, ZnS: Cu, and Al phosphors were also manufactured and evaluated under the same conditions by lighting different FEDs. Compared to Example 2, it was confirmed that the life stability was excellent.

(Example 2)
A phosphor emitting green light represented by a β-type sialon phosphor was mixed with 5 wt% of SnO ₂ fine particles having an average particle diameter of 0.5 μm as a conductive agent. This was dispersed in a solvent composed of ethyl cellulose and butyl carbitol to obtain a paste. As a result of using this phosphor paste and mounting it on an FED and evaluating the life characteristics as in Example 1, the same effect as in Example 1 was obtained in Example 2.

(Example 3)
A phosphor emitting green light represented by a β-type sialon phosphor was mixed with 5 wt% of ZnO having an average particle diameter of 0.5 μm as a conductive agent. This was dispersed in a solvent composed of ethyl cellulose and butyl carbitol to obtain a paste. When a VFD was prepared using the phosphor paste and 50 V was applied to the anode electrode, green light emission was obtained with practical luminance.

Example 4
A phosphor emitting green light represented by a β-type sialon phosphor was mixed with 5 wt% of SnO ₂ fine particles having an average particle diameter of 0.5 μm as a conductive agent. This was dispersed in a solvent composed of ethyl cellulose and butyl carbitol to obtain a paste. This was dispersed in a solvent composed of ethyl cellulose and butyl carbitol to obtain a paste. When a VFD was prepared using the phosphor paste and 50 V was applied to the anode electrode, green light emission was obtained with practical luminance as in Example 3.

  As described above, the electron beam excitation phosphor and the electron beam excitation fluorescent light emitting element described above can provide a green electron beam excitation phosphor excellent in luminance life at a driving voltage of 0.1 kV or more. In addition, when used in an electron beam excitation fluorescent light-emitting element used in a display device such as an FED or VFD, the luminance life is excellent, and thus an effect of suppressing a shift in RGB color balance is achieved.

By the way, it is desirable that the crystal phase is composed of a single phase of a sialon crystal having a β-type Si ₃ N ₄ crystal structure, but the present invention is not limited to this. For example, other crystal phases within a range in which characteristics do not deteriorate Or a mixture with an amorphous phase. In this case, the content of sialon crystals having a β-type Si ₃ N ₄ crystal structure is preferably 50% by mass or more in order to obtain high luminance.

  As mentioned above, although the best form was demonstrated using this invention, this invention is not limited with the description and drawing by this form. That is, it is a matter of course that all other forms, examples, operation techniques, and the like made by those skilled in the art based on this form are included in the scope of the present invention.

It is the graph which compared the anode voltage-anode current of the electron beam excitation fluorescence light emitting element using the fluorescent substance for electron beam excitation of this invention, and the conventional fluorescence light emission element. It is the graph which compared the luminous efficiency of the electron beam excitation fluorescence light emitting element and the conventional fluorescence light emitting element. It is the graph which compared the emission capability of the same electron beam excitation fluorescence light emitting element and the conventional fluorescence light emission element. It is a table | surface which shows the amount of chromaticity changes of the electron beam excitation fluorescence light emitting element and the conventional display element. It is sectional drawing of a general FED.

Explanation of symbols

1 Anode substrate 2 Cathode substrate 3 Field emission device (FEC)
4 Anode 5 Cathode conductor 6 Insulating layer 7 Gate 8 Hole 9 Emitter 10 Anode conductor 11 Phosphor layer

Claims (5)

It contains a β-sialon crystal in which Eu having a β-type silicon nitride crystal structure that emits fluorescence having a peak at a wavelength between 500 nm and 550 nm when irradiated with an electron beam. Phosphor. It is represented by a composition formula Eu _a Si _b Al _c O _d Ne (where a + b + c + d + e = 1), and a, b, c, d, e in the formula are
0.00001 ≦ a ≦ 0.01
0.28 ≦ b ≦ 0.46
0.001 ≦ c ≦ 0.3
0.001 ≦ d ≦ 0.3
0.4 ≦ e ≦ 0.62
The phosphor for electron beam excitation according to claim 1, comprising a β-type sialon crystal that satisfies the following condition. 3. An electron beam-excited fluorescent light-emitting element using the electron beam excitation phosphor according to claim 1 or 2. The fluorescent light emitting device for electron beam excitation according to claim 3, wherein the electron beam excited fluorescent light emitting device is an electroluminescent device. 4. The electron beam excited fluorescent light emitting device according to claim 3, wherein the electron beam excited fluorescent light emitting device is a fluorescent display tube.

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