JP2007161891A - Fluorophor and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluorophor which is chemically stable, has a long life, and does not contain Cd. <P>SOLUTION: This fluorophor is represented by the general formula: (Sc<SB>1-x</SB>Tm<SB>x</SB>)Ca<SB>4</SB>O(BO<SB>3</SB>)<SB>3</SB>(0<x≤1). The method for producing the fluorophor comprises a process for weighing starting materials: Sc<SB>2</SB>O<SB>3</SB>, Tm<SB>2</SB>O<SB>3</SB>, CaCO<SB>3</SB>, B<SB>2</SB>O<SB>3</SB>, a process for mixing the starting materials to form mixed materials, a process for charging the mixed materials into a heat-resistant container and calcining the charged mixed materials in the atmosphere to obtain the calcination product. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a phosphor and a manufacturing method thereof, and more particularly to a phosphor suitable for electron beam excitation and a manufacturing method thereof.

  A phosphor that absorbs excitation energy such as an electron beam and emits fluorescence includes a cathode ray tube (CRT), a fluorescent display (VFD), and a display using a field emission cathode as an electron source (field emission display, FED) and field emission lamps (FEL).

  The FED is a display that is excited by applying an electron beam to a phosphor to visually observe visible light emitted from the phosphor. Since the surface where the electron beam generator and the phosphor excited by the electron beam are applied constitutes a single display cell, and a large number of display cells can be arranged on a flat surface, a thin display can be realized. It becomes. It is expected as a wall-mounted television for home use and a display device in public places. FEL is a lamp that emits light by irradiating a phosphor with an electron beam, and is expected to have high efficiency.

Examples of phosphors used in CRT and FED include ZnS: Zn (Zn-activated ZnS) for blue light emission, ZnO: Zn (Zn-activated ZnO) for green light emission, ZnS: Cu, Al (ZnS activated by Cu, Al), (Zn, Cd) S: Ag (Ag-activated (Zn, Cd) S), (Zn, Cd) S: Ag, Cl (Ag for red light emission) , Cl-activated (Zn, Cd) S), Y ₂ O ₂ S: Eu (Eu-activated Y ₂ O ₂ S), and the like have been used. ZnO: A sulfide phosphor other than Zn.

  Sulfide phosphors have problems such as the sulfur component decomposed and separated from the base material due to collision of electrons and adhering to the cathode surface to cause characteristic deterioration (decrease in luminance), and materials containing Cd may cause environmental problems. (Patent Document 1).

JP 2001-81459 A

As phosphors used in fluorescent lamps, blue-emitting barium magnesium aluminate phosphors (BaMgAl ₁₀ O ₁₇ : Eu) and strontium chloroapatite phosphors (Sr, Ca, Ba) ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu) Also known are green-emitting lanthanum phosphate phosphors (LaPO ₄ : Ce, Tb), cerium magnesium aluminate phosphors (CeMgAl ₁₁ O ₁₉ : Tb), red-emitting Y ₂ O ₃ : Eu, and the like. These phosphors have problems such that the amount of light decreases and the color changes when the temperature increases (Patent Document 2).
Japanese Patent Laid-Open No. 10-77470

  There is a demand for phosphors that have high brightness, are chemically stable, and do not cause environmental problems.

When the three primary colors are formed as a display, if the phosphor bases are greatly different, the firing temperatures are often different, and the three primary color phosphors need to be fired at different temperatures.
The present inventors, as a phosphor with previously oxides, performing high luminance red light emission _{(Y 1-x Eu x)} Ca 4 O (BO 3) 3 (0 <x <1), high intensity green proposed a light emitting performing _{(Y 1-x Tb x)} Ca 4 O (BO 3) 3 (0 <x <1). These phosphors can be said to be RECa ₄ O (BO ₃ ) ₃ (RE is a rare earth element) -based phosphor (Patent Documents 3 and 4).
JP 2005-68364 A JP 2005-68365 A

  In this material system, sufficient light emission has not yet been obtained for blue.

An object of the present invention is to provide a phosphor that is chemically stable, has a long lifetime, and does not contain Cd.
Another object of the present invention is to provide a RECa ₄ O (BO ₃ ) ₃ (RE is a rare earth element) -based phosphor capable of emitting high-luminance blue light.

  Still another object of the present invention is to provide a light emitting device having three primary color phosphors that are chemically stable, have a long life, do not contain Cd, and have uniform characteristics.

According to one aspect of the present invention,
There is provided a phosphor containing a substance obtained by substituting the rare earth site of rare earth calcium oxyborate with Sc, Tm.

According to another aspect of the present invention, a blue-emitting phosphor containing a material obtained by substituting rare earth sites of rare earth calcium oxyborate with Sc, Tm;
A green-emitting phosphor containing a material obtained by substituting the rare earth sites of rare earth calcium oxyborate with Y, Tb;
A red light-emitting phosphor containing a substance obtained by substituting the rare earth sites of rare earth calcium oxyborate with Y, Eu;
Electron beam source;
An electron beam-excited light emitting device is provided.

According to yet another aspect of the present invention,
Weighing starting materials Sc ₂ O ₃ , Tm ₂ O ₃ , CaCO ₃ , B ₂ O ₃ ;
Mixing the starting materials to form a mixed material;
Filling the mixed material into a heat-resistant container and firing in an air atmosphere to obtain a fired product;
A method for producing a phosphor containing the above is provided.

It has no hygroscopicity, is chemically stable and has a long life.
It is possible to provide phosphors of three primary colors using the same base material.

Rare earth calcium oxyborate (RECa ₄ O (BO ₃ ) ₃ ; RE is a rare earth element) has no hygroscopicity, is a highly stable substance, and is less damaged by the laser. Applications are being made.

  FIG. 1 shows the crystal structure of rare earth calcium oxyborate. Any of the 17 rare earth elements of Sc, Y, and lanthanides (atomic numbers 57 to 71) belonging to Group 3 of the periodic table enters the hatched atomic positions.

The inventors of the present invention perform red light emission by using YCa ₄ O (BO ₃ ) ₃ as a base material and substituting part of Y with Eu (Y _1-x Eu _x ) Ca ₄ O (BO ₃ ) _3. (0 <x <1), and (Y _1−x Tb _x ) Ca ₄ O (BO ₃ ) ₃ (0 <x <1) that emits green light by substituting a part of Y with Tb. These are chemically stable high brightness phosphors. Although fluorescence by ultraviolet excitation has been reported, it is also possible to emit light by electron beam excitation.

FIG. 2A shows a cathodoluminescence spectrum in which (Y _1-x Eu _x ) Ca ₄ O (BO ₃ ) ₃ powder is irradiated with an electron beam to measure light emission. Red light emission having a peak in the vicinity of a wavelength of 620 nm was confirmed.

FIG. 2B shows a cathodoluminescence spectrum in which (Y _1-x Tb _x ) Ca ₄ O (BO ₃ ) ₃ powder is irradiated with an electron beam to measure light emission. Green light emission showing a peak in the vicinity of a wavelength of 540 nm was confirmed.

  In order to obtain a color display, a blue phosphor is also necessary. If the base is made of the same rare earth calcium oxyborate as the red and green phosphors, three primary color phosphors with uniform characteristics can be obtained.

_Therefore, the YCa 4 O _{(BO 3)} 3 as a host, a part of Y was prepared was replaced with _{Tm (Y 1-x Tm x} ) Ca 4 O (BO 3) 3. However, sufficient blue fluorescence was not obtained. It is conceivable that light emission by the Tm ³⁺ center is strongly influenced by the crystal field in the electron arrangement via a charge transfer state (CTS) in which one electron has moved from the base. The ionic radius of Y ³⁺ is 0.900A, and the ionic radius of Tm ³⁺ is 0.880A. Even if Y ³⁺ is replaced with Tm ³⁺ , the distortion of the crystal field will be small. By increasing the distortion of the crystal field is expected to increase the fluorescence _properties, YCa 4 O _{(BO 3)} in place of _{3, ScCa 4 O (BO 3} ) 3 maternal that the Sc on one period of rare earth elements And replacing Sc with Tm was considered. The ion radius of Sc ³⁺ is 0.745A, which is very different from the ion radius 0.880A of Tm ³⁺ .

Sc ₂ O ₃ , Tm ₂ O ₃ , CaCO ₃ , and B ₂ O ₃ phosphor raw materials were weighed and sufficiently mixed in a dry mixer. This primary mixture was tightly filled into a heat-resistant container made of alumina, and calcined and fired at 1000 ° C. for 10 hours in an air atmosphere type electric furnace. This calcined fired product was pulverized and sufficiently mixed again with a dry mixer. This secondary mixture was tightly filled into an alumina heat-resistant container and subjected to main firing in an air atmosphere type electric furnace at 1200 ° C. for 12 hours. The secondary fired product was pulverized and sieved to obtain a phosphor having a composition of (Sc _1-x Tm _x ) Ca ₄ O (BO ₃ ) ₃ .

FIG. 3A shows an X-ray diffraction pattern of (Sc _0.98 Tm _0.02 ) Ca ₄ O (BO ₃ ) ₃ powder. A diffraction peak due to the rare earth calcium oxyborate appears, no heterogeneous phase is seen, and it is considered that almost perfect (Sc _0.98 Tm _0.02 ) Ca ₄ O (BO ₃ ) ₃ is formed.

FIG. 3B shows a cathodoluminescence spectrum in which (Sc _0.98 Tm _0.02 ) Ca ₄ O (BO ₃ ) ₃ powder is irradiated with an electron beam to measure light emission. Luminescence peaks appeared near 460 nm and 480 nm, and blue luminescence was observed.

It can be seen that a novel phosphor was obtained by substitution synthesis of rare earth sites of rare earth calcium oxyborate with Sc and Tm. The new phosphor is composed of ScCa ₄ O (BO ₃ ) ₃ and TmCa ₄ O (BO ₃ ) _{3 and} has the general formula (Sc _1-x Tm _x ) Ca ₄ O (BO ₃ ) ₃ (where 0 <x A phosphor represented by ≦ 1).

Further, by combinatorial method, binary composition gradient layer whose composition changes gradually _{(Sc 1-x Tm x)} Ca 4 O (BO 3) 3 was to prepare a sample. FIG. 4 shows a schematic diagram of a combinatorial apparatus. Using a pulsed laser deposition apparatus provided with a KrF excimer laser EL, a fired product target 4 of ScCa ₄ O (BO ₃ ) ₃ and TmCa ₄ O (BO ₃ ) ₃ as both end materials is formed. A body membrane 2 was produced. The ultimate vacuum in the chamber 6 is 3 × 10 ⁻⁹ torr, oxygen is supplied from the oxygen cylinder 5 at the time of film formation, and the partial pressure of oxygen is 1 × 10 ⁻⁶ torr. A phosphor was laser-deposited on the substrate 1. The binary composition gradient phosphor film 2 was formed by alternately depositing the target 4 on the laser and adjusting the movable mask 3.

  Although the film obtained at a substrate temperature of 700 ° C. or lower was in an amorphous state, high-luminance fluorescence characteristics were obtained. When the substrate temperature is higher than 700 ° C., a polycrystalline film is obtained, but the fluorescence characteristics are obtained similarly. The amorphous phase phosphor emitted higher brightness fluorescence. When forming a phosphor thin film, it is more desirable to form an amorphous phase film. When sapphire was used as the transparent substrate, an amorphous phase was obtained at less than 700 ° C., and a polycrystalline film was obtained at 700 ° C. or more.

The optimum composition region could be examined by irradiating an electron beam to the binary composition gradient film (Sc _1-x Tm _x ) Ca ₄ O (BO ₃ ) ₃ and evaluating the light emission characteristics of the light emission region.
FIG. 5 is a perspective view schematically showing a sample. A compositionally graded phosphor film 2 of (Sc _1-x Tm _x ) Ca ₄ O (BO ₃ ) ₃ is formed on a quartz glass substrate 1. As shown in FIG. 6, the composition is such that the left end of the substrate sample is TmCa ₄ O (BO ₃ ) ₃ and the Tm concentration decreases and the Sc concentration gradually increases as it goes to the right, and the right end is ScCa ₄ O (BO ₃ ). _It is comprised so that it may become ₃ compositions.

For cathodoluminescence, the above sample was placed in a vacuum chamber, and the state of light emission was observed visually by irradiating an electron beam from above. The composition of (Sc _1-x Tm _x ) Ca ₄ O (BO ₃ ) ₃ that is more preferable as a blue phosphor than the observed light emitting part is:
0 <x ≦ 0.04
Met. In particular,
0.001 <x ≦ 0.03
Was the optimum composition range.

_{Incidentally, (Sc 1-x Tm x} ) Ca 4 O (BO 3) 3 when forming the phosphor _{film, ScCa 4 O (BO 3)} 3 and TmCa ₄ O _{(BO 3)} 3 and the two sintered bodies of In addition to using a target, a fired product having a mixed crystal composition may be used as a target. The film formation is not limited to laser MBE, but may be performed by EB vapor deposition, sputtering, ion plating, laser ablation, or the like. It is also possible to stack films having different compositions by controlling the thickness at the level of one atomic layer. In addition, a known method such as printing the powdery phosphor as a paste can be used.

  FIG. 6 is a cross-sectional view schematically showing the configuration of the field emission display. The opposing substrates 11 and 12 are, for example, glass substrates, and a cathode electrode CE and an anode electrode AE are formed on the opposing surfaces. The anode electrode AE is formed of a transparent electrode such as indium tin oxide (ITO). On the cathode electrode CE, conductive microchips 15 are formed of silicon or the like in a number of rows and a number of columns. A gate electrode GE for each microchip is formed so as to surround the tip of the microchip 15. When a positive high voltage is applied to the gate electrode GE, an electron beam is emitted from the tip of the microchip 15. A phosphor film 20 formed on the anode electrode AE is disposed in the traveling direction of the electron beam. The phosphor film 20 is arranged as a set of red (R), green (G), and blue (B). The phosphors that have received the electron beam emit light and display a color image. The brightness is controlled by controlling the light emission time.

RGB phosphors, performs red emission above _{(Y 1-x Eu x)} Ca 4 O (BO 3) 3 (0 <x <1), performs the green light emission _{(Y 1-x Tb x)} Ca 4 O (BO ₃ ) ₃ (0 <x <1), which emits blue light (Sc _1-x Tm _x ) Ca ₄ O (BO ₃ ) ₃ (0 <x ≦ 0.04). Since the bases of the three primary color phosphors are all rare earth calcium oxyborate, the firing temperature after forming the phosphor film can be made uniform and fired simultaneously.

  FIG. 7 shows an embodiment of an electron beam irradiation phosphor lamp. For example, a cathode electrode 31 serving as an electron source, for example, a surface roughened by plasma etching is inserted into a shell-type vacuum glass container 30. A cathode used as an electron emission source and the phosphor of the present invention mixed with a binder on the anode side (electrode is ITO or the like) surface or a thin film deposited is opposed to each other as an anode. When a voltage of, for example, 10 kV is applied between the two electrodes, electrons are emitted from the cathode, and light is emitted by colliding with the phosphor on the anode to form a lamp. This anode may be a so-called aluminum pack system in which a phosphor is applied in advance and then Al is deposited by vapor deposition or the like. Moreover, you may use an elongate pipe | tube, a bowl-shaped thing, etc. as a shape of a glass container.

  Another example of the electron beam irradiation phosphor lamp is a flat light source lamp. An anode electrode made of ITO or the like is formed on one side of a glass counter substrate, and a cathode electrode made of an Al film or the like is formed on the other side. On the anode electrode, the phosphor film of the present embodiment is formed. A paste containing carbon nanotubes is applied on the cathode electrode. When a voltage of, for example, 10 kV is applied between the two electrodes, electrons are emitted from the cathode side, and light is emitted by colliding with the phosphor film to form a lamp.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

  The present invention can be used for various fluorescent display devices.

It is a perspective view which shows the crystal structure of rare earth calcium oxyborate. FIG. 2A is a graph showing a spectrum of cathodoluminescence by electron beam excitation of (Y _1-x Eu _x ) Ca ₄ O (BO ₃ ) ₃ powder, and FIG. 2B shows (Y _1-x Tb _x ) Ca _4. O (BO ₃₎ is a graph showing a spectrum of cathode luminescence caused by ₃ powder electron beam excitation of. FIG. 3A is a graph showing an X-ray diffraction pattern of the prepared (Sc _1-x Tm _x ) Ca ₄ O (BO ₃ ) ₃ phosphor powder, and FIG. 3B shows a spectrum of cathodoluminescence by electron beam excitation. It is a graph. It is a schematic diagram of a combinatorial apparatus. A cross-sectional view showing a composition gradient sample, and It is sectional drawing which shows the structure of a field emission display. It is an Example of an electron beam irradiation fluorescent substance lamp.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Quartz glass substrate 2 Composition inclination fluorescent substance film 3 Movable mask 4 Target 5 Oxygen cylinder 6 Chamber 11, 12 Glass substrate EL Excimer laser AE Anode electrode CE, 31 Cathode electrode GE Gate electrode 15 Microchip 20, 32 Phosphor film 30 Glass container

Claims (11)

  A phosphor containing a substance obtained by substituting rare earth sites of rare earth calcium oxyborate with Sc and Tm. The phosphor according to claim 1, wherein the substance is represented by a general formula (Sc _1−x Tm _x ) Ca ₄ O (BO ₃ ) ₃ (0 <x ≦ 0.04).   The phosphor according to claim 2, wherein the composition x is 0.001 <x ≦ 0.03. A blue-emitting phosphor containing a material obtained by substituting the rare earth sites of rare earth calcium oxyborate with Sc, Tm;
A green-emitting phosphor containing a material obtained by substituting the rare earth sites of rare earth calcium oxyborate with Y, Tb;
A red light-emitting phosphor containing a substance obtained by substituting the rare earth sites of rare earth calcium oxyborate with Y, Eu;
Electron beam source;
The electron beam excitation light-emitting device which has this.   The electron beam excitation light-emitting device according to claim 4, wherein the electron beam excitation light-emitting device is a display.   The electron beam excited light emitting device according to claim 4, wherein the electron beam excited light emitting device is a lamp. The blue light-emitting phosphor contains a substance represented by the general formula (Sc _1-x Tm _x ) Ca ₄ O (BO ₃ ) ₃ (0 <x ≦ 0.04),
The green-emitting phosphor comprises a substance represented by the general formula _{(Y 1-y Tb y)} Ca 4 O (BO 3) 3 (0 <y <1),
The red light-emitting phosphor includes a substance represented by the general formula (Y _1-z Eu _z ) Ca ₄ O (BO ₃ ) ₃ (0 <z <1).
The electron beam excitation light-emitting device of any one of Claims 4-6.   The electron beam excitation light-emitting device according to claim 7, wherein x is 0.001 <x ≦ 0.03. Weighing starting materials Sc ₂ O ₃ , Tm ₂ O ₃ , CaCO ₃ , B ₂ O ₃ ;
Mixing the starting materials to form a mixed material;
Filling the mixed material into a heat-resistant container, firing in an air atmosphere, and obtaining a fired product;
The manufacturing method of the fluorescent substance containing this. further,
Crushing the fired product;
Mixing the pulverized fired product to form a secondary mixed material;
Filling the secondary mixed material into a heat-resistant container and firing in an air atmosphere to obtain a secondary fired product;
The manufacturing method of the fluorescent substance of Claim 9 containing this. further,
Crushing the secondary fired product,
Sieving the pulverized secondary fired product,
The manufacturing method of the fluorescent substance of Claim 10 containing this.