JP2009096823A - Phosphor and light emitting tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide phosphor powder having a blue color or an orange to red color. <P>SOLUTION: The phosphor is a solid solution of an RMSi<SB>4</SB>N<SB>7</SB>crystal (wherein an R element is at least one element selected from the group consisting of La, Lu, Y and Sc; an M element is Ca and/or Mg) or its solid solution crystal and an A element (wherein the A element is at least one element selected from the group consisting of Mn, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Er, Tm and Yb) at the least. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a phosphor composed of an inorganic crystal that emits fluorescence by excitation energy from an excitation source or a solid solution crystal thereof, and more specifically, a phosphor having a characteristic of emitting light having a peak at a wavelength of 420 nm to 670 nm. The present invention relates to a lighting apparatus and a light emitting apparatus for an image display device using the same.

  The phosphor is a fluorescent display tube (VFD (Vacuum-Fluorescent Display)), a field emission display (FED (Field Emission Display)), or an SED (Surface-Conduction Electron-Emitter Display (P panel)). ), Cathode ray tube (CRT (Cathode-Ray Tube)), white light emitting diode (LED (Light-Emitting Diode)), and the like. In any of these applications, in order to make the phosphor emit light, it is necessary to supply the phosphor with energy for exciting the phosphor, and the phosphor is not limited to vacuum ultraviolet rays, ultraviolet rays, electron beams, blue light, etc. When excited by a high energy excitation source, it emits visible light. However, as a result of the phosphor being exposed to the excitation source as described above, there is a demand for a phosphor that is liable to lower the luminance of the phosphor and that does not have a decrease in luminance. For this reason, sialon phosphors and oxynitride phosphors are used as phosphors with little reduction in luminance instead of phosphors such as conventional silicate phosphors, phosphate phosphors, aluminate phosphors, and sulfide phosphors. For example, phosphors based on inorganic crystals containing nitrogen in the crystal structure, such as nitride phosphors, have been proposed.

An example of a sialon phosphor is manufactured by a manufacturing process generally described below. First, silicon nitride (Si ₃ N ₄ ), aluminum nitride (AlN), and europium oxide (Eu ₂ O ₃ ) are mixed at a predetermined molar ratio, and the temperature is 1700 ° C. in nitrogen at 1 atm (0.1 MPa). It is manufactured by holding for 1 hour and firing by a hot press method (see, for example, Patent Document 1). It has been reported that α sialon activated by Eu ²⁺ ions obtained by this process becomes a phosphor that emits yellow light of 550 to 600 nm when excited by blue light of 450 to 500 nm. In addition, a phosphor obtained by adding a rare earth element to β-type sialon (see Patent Document 2) is known. A phosphor activated with Tb, Yb, or Ag becomes a phosphor emitting green light of 525 nm to 545 nm. It is shown. Furthermore, a green phosphor obtained by activating Eu ²⁺ on a β-type sialon (see Patent Document 3) is known.

An example of an oxynitride phosphor, JEM phase _{(LaAl (Si 6-z Al} z) N 10-z O z) blue phosphor were activated with Ce as host crystals (see Patent Document 4), La ₃ A blue phosphor in which Ce is activated using Si ₈ N ₁₁ O ₄ as a base crystal (see Patent Document 5) is known.

As an example of a nitride phosphor, a red phosphor (see Patent Document 6) in which Eu ²⁺ is activated using CaAlSiN ₃ as a base crystal is known.

As a blue phosphor for use in an image display device (VFD, FED, SED, CRT) using an electron beam as an excitation source, a phosphor in which Ce is solid-solved with Y ₂ SiO ₅ as a base crystal (Patent Document 7) or ZnS A phosphor (Patent Document 8) in which a light-emitting ion such as Ag is dissolved is reported.

Non-Patent Document 1 reports a crystal structure of SrYSi ₄ N ₇ crystal, which is silicon nitride containing Sr, and a phosphor in which Eu ²⁺ or Ce ³⁺ is activated. The SrYSi ₄ N ₇ crystal activated by Eu ²⁺ is a phosphor that emits green at 550 nm when excited by ultraviolet rays. SrYSi ₄ N ₇ crystal activated with Ce ³⁺ is a phosphor that emits blue light of 450 nm when excited by ultraviolet rays of 350 nm or less. However, the emission intensity of these phosphors was low.

Japanese Patent No. 3668770 JP-A-60-206889 Japanese Patent No. 3921545 International Publication No. 2005/019376 Pamphlet JP 2005-112922 A Japanese Patent No. 3837588 JP 2003-55657 A JP 2004-285363 A Y. Q. Li et al., "Preparation, structure and photoluminescence properties of Eu2 + and Ce3 +-doped SrYSi4N7", Journal of Solid State Chemistry, pp. 1994, p.

  For applications such as white LEDs and plasma displays that use ultraviolet LEDs and blue LEDs as excitation sources, fluorescent materials that emit various colors such as blue, green, yellow, orange, and red as durable and high-luminance phosphors. The body is sought. Furthermore, conventional phosphors using oxynitride as a host are insulating materials, and even when irradiated with an electron beam, the emission intensity is low, and the electron beam excitation is high for electron beam-excited image display devices such as FED. There is a need for phosphors that emit light with high brightness. In addition, if there are phosphors made of various materials, they can be appropriately selected according to the use, which is preferable in terms of design.

  The oxide phosphor disclosed in Patent Document 7 used for electron beam excitation may deteriorate during use and decrease the emission intensity, and the color balance may change in the image display device. The sulfide phosphor disclosed in Patent Document 8 may be decomposed during use, and sulfur may be scattered to contaminate the device.

  An object of the present invention is to respond to such a demand, and is to provide a phosphor made of a material different from conventional rare earth activated sialon phosphors and oxide phosphors. The aim is to provide orange to red phosphor powder. Furthermore, it is intended to provide a phosphor powder that emits light efficiently with an electron beam.

In the present inventors, under these _{circumstances, CaYSi 4 N 7 RMSi 4 N} 7 crystals such as crystal or CaLaSi ₄ N ₇ crystals (where selected R element La, Lu, from the group consisting of Y and Sc At least one element, and M element is Ca and / or Mg) or a solid solution crystal thereof, and at least A element (where A element is Mn, Ce, Pr, Nd, Sm, Eu) , Tb, Dy, Er, Tm, and Yb, which are at least one element selected from the group consisting of an inorganic crystal and a solid solution, as a result of earnest research, a specific composition range and a specific solid solution state It has also been found that those having a specific crystal phase become high-luminance phosphors. Among them, those with a specific composition range in which Ce or Eu is dissolved have high-luminance blue or orange to red emission by excitation with ultraviolet rays or electron beams, and are used for illumination applications or images excited with electron beams. I found it suitable for display devices.

According to Non-Patent Document 1, although the crystal structure and light emission characteristics of SrYSi ₄ N ₇ crystal are clarified, there is no description about a phosphor using CaYSi ₄ N ₇ crystal or CaLaSi ₄ N ₇ crystal as a host. In addition, the phosphor based on the SrYSi ₄ N ₇ crystal has a problem of low emission intensity.

  As a result of further diligent research based on this knowledge, we have succeeded in providing a phosphor exhibiting a high-luminance light emission phenomenon in a specific wavelength region, a lighting fixture and an image display device having excellent characteristics. The details will be described below.

The phosphor of the invention 1 is a phosphor made of an inorganic crystal that emits fluorescence by excitation energy from an excitation source, and the inorganic crystal is an RMSi ₄ N ₇ crystal (provided that R element is La, Lu, Y, and It is at least one element selected from the group consisting of Sc, and M element is Ca and / or Mg) or its solid solution crystal, and at least A element (provided that A element is Mn, Ce, Pr, At least one element selected from the group consisting of Nd, Sm, Eu, Tb, Dy, Er, Tm, and Yb).
Invention 2 is the phosphor according to Invention 1, wherein the R element is La or Y, the M element is Ca, and the A element is Ce or Eu.
Invention 3 is the phosphor according to Invention 1, wherein the phosphor contains at least La or Y as the R element, contains at least Ca as the M element, contains at least Ce as the A element, and emits blue light by excitation light. It emits light.
The invention 4 is characterized in that in the phosphor of the invention 3, the excitation spectrum emits fluorescence having a peak wavelength of 340 nm to 420 nm and an emission peak wavelength of 420 nm to 500 nm.
Invention 5 includes the phosphor of Invention 1 that contains at least La or Y as the R element, at least Ca as the M element, and at least Eu as the A element, and emits orange to red light by excitation light. It is characterized by that.
Invention 6 is characterized in that the phosphor of Invention 5 emits fluorescence having an emission peak wavelength of 570 nm to 670 nm.
Invention 7, the phosphor of the invention _{1, A a R b M c Si} d O e N composition formula _f (although, a + b + c + d + e + f = 1) is indicated by the parameters a, b, c, d, e, f Is 0.00001 ≦ a ≦ 0.10
0.05 ≦ b ≦ 0.10
0.05 ≦ c ≦ 0.10
0.25 ≦ d ≦ 0.35
0 ≦ e ≦ 0.10
0.43 ≦ f ≦ 0.65
It satisfies the following conditions.
Invention 8 is an illuminating device comprising an excitation source and a phosphor that emits a fluorescence phenomenon upon irradiation thereof, wherein the excitation source is a light-emitting light source that emits light having a wavelength of 150 to 480 nm, and at least a part of the phosphor Is a phosphor according to any one of Inventions 1 to 7.
Invention 9 is an image display device comprising an excitation source and a phosphor that emits a fluorescence phenomenon upon irradiation thereof, wherein at least a part of the phosphor is any of the phosphors of Inventions 1-7. And
A tenth aspect of the present invention is the image display apparatus according to the ninth aspect, wherein the image display apparatus is any one of a fluorescent display tube (VFD), a field emission display (FED or SED), or a cathode ray tube (CRT), and the excitation source is accelerated. It is an electron beam having a voltage of 10 V to 30 kV.

The phosphor of the present invention is an RMSi ₄ N ₇ crystal (where the R element is at least one element selected from the group consisting of La, Lu, Y and Sc, and the M element is Ca and / or Mg) Or a solid solution crystal thereof as a parent crystal, and the parent crystal includes at least an A element (provided that the A element is Mn, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Er, Tm, and Yb). At least one element selected from: Thereby, since the A element functions as a light emission center in the above-described host crystal, the phosphor of the present invention emits fluorescence. Such a phosphor is used as a white LED. It is a useful phosphor that can be suitably used for VFD, FED, SED, CRT and the like because it emits light efficiently with an electron beam.

  Examples of the present invention will be described in detail below.

The phosphor of the present invention is an RMSi ₄ N ₇ crystal (where the R element is at least one element selected from the group consisting of La, Lu, Y and Sc, and the M element is Ca and / or Mg) Or a solid solution crystal thereof as a main component. Examples of the RMSi ₄ N ₇ crystal include LaCaSi ₄ N ₇ crystal and YCaSi ₄ N ₇ crystal. Further, the solid solution crystal RMSI ₄ N ₇ crystals are RMSI ₄ N ₇ as leaving oxygen / nitrogen ratio or Si / Al ratio was kept the crystal structure of the crystal is changed, the other element is added crystals . Examples of addition of other elements include those containing Al, B, Ga, Ge, Zn, Ba, Sr, Li, and O. By adding these elements, it becomes a solid solution maintaining the crystal structure.

In the present invention, these crystals can be used as host crystals. The RMSi ₄ N ₇ crystal can be identified by X-ray diffraction or neutron diffraction. Further, in addition to pure RMSi ₄ N ₇ crystal, those in which the lattice constant is changed by replacing the constituent element with another element are also included as part of the present invention. The phosphor of the present invention has an RMSi ₄ N ₇ crystal or a solid solution crystal as a base crystal, and at least an A element (the A element is Mn, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Er). , At least one element selected from the group consisting of Tm and Yb). The element A is an optically active element that becomes a light emission center. Depending on the selected element A, the phosphor of the present invention can emit fluorescence having various wavelengths.

One of the compositions of the phosphor of the present invention is a phosphor based on an inorganic crystal in which a part of N in the RMSi ₄ N ₇ crystal is substituted with O. Such a phosphor is represented by _a composition of A _a R _b M _c Si _d O _e N _f (where a + b + c + d + e + f = 1), and parameters a, b, c, d, e, and f are 0.00001 ≦ a ≦ 0.10
0.05 ≦ b ≦ 0.10
0.05 ≦ c ≦ 0.10
0.25 ≦ d ≦ 0.35
0 ≦ e ≦ 0.10
0.43 ≦ f ≦ 0.65
A composition satisfying the above condition exhibits particularly high luminous efficiency.

  Here, a is the content of luminescent ions, and if it is less than 0.00001, the luminescence intensity decreases. If it is higher than 0.10, concentration quenching is shown by the interaction between the light-emitting ions, and the light emission intensity decreases. b is a rare earth element content that does not contribute to light emission, and is preferably 0.05 or more and 0.10 or less. In other ranges, the crystal structure cannot be maintained and becomes a mixture with other crystals, resulting in a decrease in emission intensity. Ideally 0.0769 is preferred. c is the content of an alkaline earth element (here, Ca and / or Mg), and is preferably 0.05 or more and 0.10 or less. In other ranges, the crystal structure cannot be maintained and becomes a mixture with other crystals, resulting in a decrease in emission intensity. Ideally 0.0769 is preferred. d is the silicon content, preferably 0.25 or more and 0.35 or less. In other ranges, the crystal structure cannot be maintained and becomes a mixture with other crystals, resulting in a decrease in emission intensity. Ideally, 0.3077 is preferable. e is the content of oxygen and may not be included. However, when it is included for the purpose of composition control or the like, it is preferably 0.10 or less. f is the nitrogen content, preferably 0.43 or more and 0.65 or less. In other ranges, the crystal structure cannot be maintained and becomes a mixture with other crystals, resulting in a decrease in emission intensity. Ideally 0.538 is preferred.

As one of the compositions of the phosphor of the present invention, there is a phosphor in which an inorganic crystal obtained by substituting a part of Si in an RMSi ₄ N ₇ crystal with Al is a base crystal. The addition of Al changes the environment around the luminescent ions and changes the excitation and emission spectra, so that a composition suitable for the application can be selected.

One of the compositions in which Al is a solid solution is an inorganic crystal represented by RMSi _4-z Al _z O _z N _7-z (0 <z <2). By adopting this composition, since the crystal is stabilized, a large amount of Al can be dissolved, and the change in excitation and emission spectra becomes large. Therefore, a composition suitable for the application can be selected.

Among the phosphors of the present invention, those containing Eu as the optically active A element have particularly high emission intensity. Among them, a phosphor in which Eu is dissolved in LaCaSi ₄ N ₇ or YCaSi ₄ N _{7 in} which the R element is La or Y, the M element is Ca, and the A element is Eu, emits light from orange to red. Indicates. Since these phosphors emit light efficiently when irradiated with light of 405 nm or 450 nm, they are suitable for white LED applications in combination with purple LEDs or blue LEDs. _Further, indicated by _{La (Ca 1-x Eu x} ) Si 4 N 7 , or _{Y (Ca 1-x Eu x} ) Si 4 N 7, parameter x, satisfies the condition of 0.0001 ≦ x ≦ 0.5 The phosphor having the composition has particularly high emission intensity. If x is less than 0.0001, sufficient light emission cannot be obtained, and if it is more than 0.5, there is a possibility that the concentration may be quenched by interference between ions and the luminance may be lowered.

  In the phosphor of the present invention, the phosphor containing La or Y as the R element, Ca as the M element, and Ce as the A element has a peak wavelength of excitation spectrum of 340 nm to 420 nm in photoluminescence, When excited with an electron beam, X-ray, or the like, it exhibits light emission characteristics such that the emission peak wavelength is 420 nm or more and 500 nm or less. Preferred as a blue phosphor for white LED applications and display applications in combination with ultraviolet LEDs.

  In the phosphor of the present invention, a phosphor containing La or Y as the R element, Ca as the M element, and Eu as the A element emits an emission peak when excited with ultraviolet light, blue light, electron beam, X-ray, or the like. The emission characteristics of orange to red having a wavelength of 570 nm to 670 nm are shown. Preferred as an orange or red phosphor for white LED applications or display applications in combination with ultraviolet LEDs or blue LEDs.

  When the phosphor of the present invention is used as a powder, the average particle size is preferably 0.1 μm or more and 20 μm or less from the viewpoints of dispersibility in a resin and fluidity of the powder. Further, by making the powder into single crystal particles in this range, the emission luminance is further improved.

  Since the phosphor of the present invention emits light efficiently when excited with ultraviolet light or visible light having a wavelength of 150 nm or more and 480 nm or less, it is preferable for lighting applications. In particular, it emits light efficiently when irradiated with light of 360 nm to 400 nm emitted from ultraviolet LED, light of 405 nm emitted from purple LED, and light of 450 nm emitted from blue LED. Is suitable. Furthermore, the phosphor of the present invention can be excited by an electron beam or an X-ray. In particular, electron beam excitation emits light more efficiently than other nitride phosphors, and therefore is preferable for use in electron beam excitation image display devices.

  By irradiating the phosphor of the present invention with an excitation source, fluorescence having a peak in a wavelength range of 420 nm to 670 nm is emitted, and the emitted color varies depending on the additive element.

In the present invention, from the viewpoint of fluorescence emission, it is desirable that the constituent component, RMSi ₄ N ₇ crystal, or its solid solution crystal is highly pure and contains as much as possible, preferably composed of a single phase. It can also be composed of a mixture with other crystalline phase or amorphous phase as long as it does not decrease. In this case, the content of the RMSi ₄ N ₇ crystal or its solid solution crystal is preferably 5% by mass or more, more preferably 50% by mass or more in order to obtain high luminance. In the present invention, “comprising RMSi ₄ N ₇ crystal or its solid solution crystal as a main component” means that the content of at least RMSi ₄ N ₇ crystal or its solid solution crystal is 5% by mass or more.

The content ratio can be determined by performing X-ray diffraction measurement and performing Rietveld analysis on the RMSi ₄ N ₇ crystal, or its solid solution crystal and other crystal phases. In a simple manner, for the RMSi ₄ N ₇ crystal, or its solid solution crystal and other crystal phases, it can be determined from the ratio of the strengths of the strongest peaks of the respective phases.

  In a phosphor composed of a mixture with another crystal phase or an amorphous phase, it can be a mixture with a conductive inorganic substance. When the phosphor of the present invention is excited with an electron beam in VFD, FED, etc., it is preferable to have a certain degree of conductivity so that electrons do not accumulate on the phosphor and escape to the outside. As the conductive substance, an oxide, an oxynitride, a nitride, or a mixture thereof containing one or more elements selected from Zn, Ga, In, and Sn can be given. Among these, indium oxide and indium-tin oxide (ITO) are preferable because they have little decrease in fluorescence intensity and high conductivity.

The phosphor of the present invention develops a single color ranging from blue to red determined by the composition, but if it is necessary to mix with other colors, the phosphors that develop these colors should be mixed as necessary. Can do. Other phosphors that can be used include oxides, sulfides, oxysulfides, oxynitrides, and crystals that use nitride crystals as the host, but when the durability of the mixed phosphor is required. Preferably, oxynitride or nitride crystal is used as a host. Phosphors having oxynitride or nitride crystal as a host include α-sialon: Eu yellow phosphor, β-sialon: Eu green phosphor, α-sialon: Ce blue phosphor, CaAlSiN ₃ : Eu (Ca, Sr) AlSiN ₃ : Eu red phosphor (Ca part of CaAlSiN ₃ crystal is replaced with Sr), blue phosphor hosting JEM phase (LaAl (Si _6-z Al _z ) N _{10-z O z): Ce} ), La 3 Si 8 N 11 O 4: blue phosphor Ce, AlN: blue phosphor Eu, and the like.

  The phosphor of the present invention has a different excitation spectrum and fluorescence spectrum depending on the composition, and can be set to have various emission spectra by appropriately selecting and combining them. What is necessary is just to set the aspect to the spectrum required based on a use.

  Although the manufacturing method of the fluorescent substance of this invention is not specifically limited, The following method can be mentioned as an example.

Metals containing A, oxides, carbonates, nitrides, fluorides, chlorides, oxynitrides or combinations thereof and metals containing R, oxides, carbonates, nitrides, fluorides, chlorides, acids Nitride or combinations thereof, metals containing M, oxides, carbonates, nitrides, fluorides, chlorides, oxynitrides or combinations thereof, silicon-containing raw materials, and optionally aluminum Prepare the ingredients. In the case of synthesizing a high-purity phosphor that does not contain Al, it is preferable to use an oxide or nitride of A, a nitride of R, a nitride of M, or silicon nitride. When using A nitride, R nitride, or M nitride as raw materials, mixing in a glove box filled with an inert gas such as nitrogen or argon is recommended to prevent reaction with oxygen and moisture. . The mixture of these raw materials is filled in a container in a state where the relative bulk density is maintained at a filling rate of 40% or less. Then, it is fired in a temperature range of 12 × 10 ² ° C. to 22 × 10 ² ° C in an atmosphere containing nitrogen of 5 × 10 ⁻² MPa to 1 × 10 ² MPa. By doing so, it is possible to manufacture the phosphor of the present invention in which at least A is dissolved in the RMSi ₄ N ₇ crystal or its solid solution crystal. The optimum firing temperature may vary depending on the composition, and can be optimized as appropriate. In general, it is preferable to bake in a temperature range of 12 × 10 ² ° C to 22 × 10 ² ° C. In this way, a high-luminance phosphor can be obtained. When the firing temperature is lower than 12 × 10 ² ° C., the generation rate of the RMSi ₄ N ₇ crystal or its solid solution crystal may be low. Further, when the firing temperature is higher than 22 × 10 ² ° C., a special apparatus is required, which is not industrially preferable.

  As the starting material of the silicon source, metal silicon, silicon oxide, silicon nitride, organic precursor containing silicon, silicon diimide, amorphous body obtained by heat treatment of silicon diimide, etc. can be used. For this, silicon nitride can be used. In addition to being able to obtain a highly pure synthetic product with high reactivity, these have the advantage that they are produced as industrial raw materials and are easily available. As silicon nitride, α-type, β-type, amorphous body, and a mixture thereof can be used.

  As a starting material for the aluminum source, metal aluminum, aluminum oxide, aluminum nitride, an organic precursor containing aluminum, and the like can be used. Usually, a mixture of aluminum nitride and aluminum oxide is preferably used. In addition to being able to obtain a highly pure synthetic product with high reactivity, these have the advantage that they are produced as industrial raw materials and are easily available.

  In order to improve the reactivity at the time of baking, the inorganic compound which produces | generates a liquid phase at the temperature below a calcination temperature can be added to the mixture of a starting material as needed. As the inorganic compound, those that generate a stable liquid phase at the reaction temperature are preferable. Li, Na, K, Mg, Ca, Sr, Ba, Al oxides, nitrides, oxynitrides, fluorides, Chloride, iodide, bromide or phosphate are suitable. Furthermore, these inorganic compounds may be added alone or in combination of two or more. Of these, calcium fluoride and aluminum fluoride are preferable because of their high ability to improve the reactivity of synthesis. However, when adding an inorganic compound that is a constituent element of the phosphor, it is necessary to pay attention to variations in the composition. The addition amount of the inorganic compound is not particularly limited, but the effect is particularly great when it is 0.1 to 10 parts by weight with respect to 100 parts by weight of the mixture of the metal compound as the starting material. When the amount is less than 0.1 parts by weight, the reactivity is not improved, and when the amount exceeds 10 parts by weight, the luminance of the phosphor may be lowered. When these inorganic compounds are added and baked, the reactivity is improved, grain growth is promoted in a relatively short time, and a single crystal having a large grain size grows, thereby improving the luminance of the phosphor.

The nitrogen atmosphere is preferably a gas atmosphere having a pressure range of 5 × 10 ⁻² MPa to 1 × 10 ² MPa. More preferably, it is 1 × 10 ⁻¹ MPa or more and 1 × 10 ¹ MPa or less. When using silicon nitride as the raw material, when heated to a temperature above 1820 ° C. at 1 × 10 -1 ^MPa lower nitrogen gas atmosphere, less preferred because the raw material is easily thermally decomposed. 1 × 10 ¹ MPa is sufficient, and if it exceeds 1 × 10 ² MPa, a special apparatus is required, which is not suitable for industrial production. Further, a mixed gas of nitrogen and hydrogen can be used as necessary. By using a mixed gas, the chemical stability of the raw material in a relatively low temperature region is improved, so that a high-quality product can be obtained.

When a fine powder having a particle size of several μm is used as a starting material, the mixture of metal compounds after the mixing step is in a form in which fine powder having a particle size of several μm is aggregated to a size of several hundred μm to several mm (hereinafter referred to as “a”). Called "powder agglomerates"). In the present invention, the powder aggregate is fired in a state where the bulk density is maintained at a filling rate of 40% (2/5) or less. More preferably, the bulk density is 20% (1/5) or less. Here, the relative bulk density is a ratio of a value (bulk density) obtained by dividing the mass of the powder filled in the container by the volume of the container and the true density of the substance of the powder. In normal sialon production, a hot press method in which heating is performed while applying pressure or a production method in which baking is performed after mold forming (compacting) is used, but the firing at this time is performed with a high powder filling rate. . However, in the present invention, the powder powder aggregates having the same particle size without being mechanically applied to the powder or previously molded using a mold or the like are used as they are. Etc. are filled with a bulk density of 40% (2/5) or less. If necessary, the powder aggregate can be granulated to an average particle size of 5 × 10 ² μm or less using a sieve or air classification, and the particle size can be controlled. Further, it may be granulated directly into 5 × 10 ² μm or less in shape by using a spray dryer. Further, when the container is made of boron nitride, there is an advantage that there is little reaction with the phosphor.

The reason for firing while maintaining the bulk density at 40% (2/5) or less is to fire in a state where there is a free space around the raw material powder. The optimum bulk density varies depending on the shape and surface state of the granular particles, but is preferably 20% (1/5) or less. In this way, the reaction product grows in a free space, so that the contact between the crystals is reduced and a crystal with few surface defects can be synthesized. Thereby, a fluorescent substance with high brightness is obtained. If the bulk density exceeds 40% (2/5), densification occurs partially during firing, resulting in a dense sintered body that hinders crystal growth and may reduce the brightness of the phosphor. Moreover, it is difficult to obtain a fine powder. Further, the size of the powder aggregate is particularly preferably 5 × 10 ² μm or less because of excellent grindability after firing.

  Next, a powder aggregate having a filling rate of 40% (2/5) or less is fired under the above conditions. The furnace used for firing may be a metal resistance heating method or a graphite resistance heating method because the firing temperature is high and the firing atmosphere is nitrogen. An electric furnace using carbon as the material for the high temperature part of the furnace is preferred. The firing is preferably performed by a firing method in which no mechanical pressure is applied from the outside, such as an atmospheric pressure sintering method or a gas pressure sintering method, in order to perform the firing while maintaining a bulk density in a predetermined range.

  When the powder aggregate obtained by firing is hard aggregated, it is pulverized by a pulverizer generally used industrially, such as a ball mill or a jet mill. Among these, ball milling makes it easy to control the particle size. The balls and pots used at this time are preferably made of a silicon nitride sintered body or a sialon sintered body. Grinding is performed until the average particle size becomes 20 μm or less. The average particle size is particularly preferably 20 nm or more and 10 μm or less. When the average particle diameter exceeds 20 μm, the fluidity of the powder and the dispersibility in the resin are deteriorated, and the light emission intensity becomes uneven depending on the part when the light emitting device is formed in combination with the light emitting element. When the thickness is less than 20 nm, the operability for handling the powder is deteriorated. If the desired particle size cannot be obtained only by grinding, classification can be combined. As a classification method, sieving, air classification, precipitation in a liquid, or the like can be used.

  Furthermore, by washing with a solvent that dissolves the inorganic compound after firing, the content of inorganic compounds other than phosphors such as glass phase, second phase, or impurity phase contained in the reaction product obtained by firing is reduced. As a result, the luminance of the phosphor is improved. As such a solvent, water and an aqueous solution of an acid can be used. As the acid aqueous solution, sulfuric acid, hydrochloric acid, nitric acid, hydrofluoric acid, a mixture of organic acid and hydrofluoric acid, or the like can be used. Of these, a mixture of sulfuric acid and hydrofluoric acid is highly effective. This treatment is particularly effective for a reaction product obtained by adding an inorganic compound that generates a liquid phase at a temperature lower than the firing temperature and firing at a high temperature.

Although a fine phosphor powder is obtained by the above steps, heat treatment is effective for further improving the luminance. In this case, the powder after firing or the powder after particle size adjustment by pulverization or classification can be heat-treated at a temperature of 10 × 10 ² ° C. or more and less than the firing temperature. At a temperature lower than 10 × 10 ² ° C., the effect of removing surface defects is small. Above the firing temperature, the pulverized powders are fixed again, which is not preferable. Although the atmosphere suitable for the heat treatment varies depending on the composition of the phosphor, one or two or more mixed atmospheres selected from nitrogen, air, ammonia, and hydrogen can be used. Particularly, the nitrogen atmosphere is effective for defect removal. It is preferable because it is excellent.

  The phosphor of the present invention obtained as described above is characterized by having high-luminance visible light emission as compared with a normal oxide phosphor or an existing sialon phosphor. Among these, a specific composition is characterized by emitting red or blue light, and is suitable for a lighting apparatus and an image display device. In addition, since it does not deteriorate even when exposed to high temperatures, it has excellent heat resistance, and excellent long-term stability in an oxidizing atmosphere and moisture environment.

  The lighting fixture of this invention is comprised using the light-emitting light source and the fluorescent substance of this invention at least. Examples of lighting fixtures include LED lighting fixtures and fluorescent lamps. The LED lighting apparatus is manufactured by using the phosphor of the present invention by a known method as described in JP-A-5-152609, JP-A-7-99345, JP-A-2927279, and the like. Can do. In this case, it is desirable that the light emission source emits light having a wavelength of 330 to 420 nm, and among these, an ultraviolet (or purple) LED light emitting element or LD light emitting element having a wavelength of 330 to 420 nm is preferable.

  These light emitting elements include those made of nitride semiconductors such as GaN and InGaN, and can be light emitting light sources that emit light of a predetermined wavelength by adjusting the composition.

In addition to the method of using the phosphor of the present invention alone in a lighting fixture, a lighting fixture emitting a desired color can be configured by using it together with a phosphor having other light emission characteristics. As an example of this, there is a combination of a 450 nm blue LED or LD light emitting element, a green phosphor excited at this wavelength and having an emission peak at a wavelength of 500 nm to 560 nm, and the red phosphor of the present invention. An example of such a green phosphor is β-sialon: Eu ²⁺ . In this configuration, when blue light emitted from the LED or LD is irradiated to the phosphor, light of two colors, green and red, is emitted, and a white luminaire is obtained by mixing these.

As another method, an ultraviolet LED or LD light emitting device of 330 to 400 nm, a blue phosphor of the present invention having an emission peak at a wavelength of 430 nm or more and 500 nm or less excited at this wavelength, and 500 nm to 560 nm excited at this wavelength. A green phosphor having an emission peak at a wavelength of 550 nm, a yellow phosphor having an emission peak at a wavelength of 550 nm to 600 nm and excited at this wavelength, and an emission peak at a wavelength of 600 nm to 700 nm excited by this wavelength. There is a combination with a red phosphor. As such a yellow phosphor, α-sialon: Eu ²⁺ described in JP-A No. 2002-363554 and (Y, Gd) ₂ (Al, Ga) ₅ O ₁₂ described in JP-A No. 9-218149: Examples of such red phosphors for Ce ³⁺ include CaSiAlN ₃ : Eu ²⁺ described in International Publication No. 2005/052087 pamphlet. In this configuration, when ultraviolet light emitted from an LED or LD is irradiated onto a phosphor, light of four colors of blue, green, yellow, and red is emitted, and the light is mixed to produce a white or reddish light bulb-colored luminaire. It becomes.

  The image display device of the present invention is composed of at least an excitation source and the phosphor of the present invention, such as a fluorescent display tube (VFD), a field emission display (FED or SED), a plasma display panel (PDP), a cathode ray tube (CRT), etc. There is. The phosphor of the present invention has been confirmed to emit light by excitation of vacuum ultraviolet rays of 100 to 190 nm, ultraviolet rays of 190 to 380 nm, electron beams, etc., and in combination of these excitation sources and the phosphor of the present invention, An image display apparatus as described above can be configured.

  Since the phosphor of the present invention has excellent excitation efficiency of electron beams, it is suitable for VFD, FED, SED, and CRT applications that are used at an acceleration voltage of 10 V or more and 30 kV or less.

  The FED is an image display device that emits light by accelerating electrons emitted from a field emission cathode and colliding with a phosphor applied to the anode, and is required to emit light at a low acceleration voltage of 5 kV or less. By combining these phosphors, the light emission performance of the display device is improved.

  Next, the present invention will be described in more detail with reference to the following examples, which are disclosed as an aid for easy understanding of the present invention, and the present invention is limited to these examples. It is not a thing.

<Examples 1-15>
First, raw material powder was synthesized. 99% pure metal yttrium, metal europium, and metal cerium were heated to 850 ° C. in an ammonia stream to synthesize yttrium nitride, europium nitride, and cerium nitride. As the lanthanum nitride, a product manufactured by Kojundo Chemical Co., Ltd. was used. As the silicon nitride, silicon nitride powder (E10 grade manufactured by Ube Industries) having an average particle size of 0.5 μm, an oxygen content of 0.93% by weight, and an α-type content of 92% was used.

Next, phosphors were synthesized using the raw material powder of the purchased product and the synthesized product. Table 1 summarizes the design compositions of Examples 1-15. In order to obtain the design composition represented by the parameters shown in Table 1, the raw material powder is weighed at the mass ratio shown in Table 2, and the silicon nitride sintered body is kept in a glove box in which moisture and oxygen impurities are kept at 1 ppm or less in a nitrogen atmosphere. After mixing using a mortar and pestle made, a powder aggregate having excellent fluidity was obtained by passing through a sieve having an opening of 125 μm. When this powder aggregate was naturally dropped into a boron nitride crucible having an inner diameter of 20 mm and a height of 20 mm, the bulk density was 15 to 30% by volume. 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, nitrogen at a temperature of 800.degree. The pressure was 5 MPa, the temperature was raised to 1700 ° C. at 500 ° C. per hour, and held at 1700 ° C. for 2 hours. The synthesized sample was ground with a mortar and pestle made of silicon nitride, and by performing powder X-ray diffraction measurement using a K _alpha line _{Cu (XRD), RMSi 4 N} 7 crystal, or RMSI ₄ N ₇ crystals The solid solution was confirmed. Depending on the composition, a phase other than RMSi ₄ N ₇ crystal or solid solution was detected. From the ratio of the height of the main peak, the production ratio of RMSi ₄ N ₇ crystal or solid solution was judged to be 90% or more.

As a result of irradiating the powder thus obtained with a lamp emitting light having a wavelength of 365 nm, it was confirmed that light was emitted in the colors shown in Table 3. The emission spectrum and excitation spectrum of this powder were measured using a fluorescence spectrophotometer. 1 to 15 show the photoluminescence measurement results of Examples 1 to 15. FIG. These powders are phosphors that have an excitation spectrum peak at a wavelength in the range of 300 to 480 nm and emit light having an emission spectrum peak at a wavelength in the range of 420 to 650 nm upon excitation at the peak wavelength of the excitation spectrum. I understood that. In Examples 1 to 5 in which Ce was dissolved in LaCaSi ₄ N ₇ , it was a blue phosphor having an emission peak from 445 nm to 460 nm. Examples 6 to 10 in which Eu was dissolved in LaCaSi ₄ N ₇ were red phosphors having an emission peak from 610 nm to 644 nm. Examples 11 to 15 in which Eu was dissolved in YCaSi ₄ N ₇ were red phosphors having an emission peak from 608 nm to 623 nm. In addition, since the emission intensity (count value) of the excitation spectrum and the emission spectrum varies depending on the measurement apparatus and conditions, the unit is an arbitrary unit. That is, the comparison can be made only within the present embodiment measured under the same conditions.

  Regarding Example 1 to Example 15, the emission characteristics (cathode luminescence, CL) when irradiated with an electron beam were observed with an SEM equipped with a CL detector, and the CL image was evaluated. It was confirmed that it emitted light of the same color as photoluminescence.

  Next, a lighting fixture using the phosphor of the present invention will be described. In FIG. 16, the schematic structural drawing of white LED as a lighting fixture is shown. A phosphor mixture made of the nitride of the present invention and other phosphors and a blue LED chip 2 having a wavelength of 440 nm are used as a light emitting element. The mixture phosphor 1 in which the red phosphor of Example 6 of the present invention and the green phosphor of β-sialon: Eu are dispersed in the resin layer is covered on the LED chip 2 and disposed in the container 7. To do. When a current is passed through the conductive terminals 3 and 4, a current is supplied to the LED chip 2 through the wire bond 5 to emit light of 440 nm, and this light excites the phosphor mixture 1 of green phosphor and red phosphor. Thus, green and red light are emitted, respectively, and blue light from the LED chip 2 is mixed to function as an illuminating device that emits white light.

  FIG. 17 is a principle schematic diagram of a field emission display panel as an image display device. The blue phosphor of Example 1 of the present invention is applied to the inner surface of the anode 53. By applying a voltage between the cathode 52 and the gate 54, electrons 57 are emitted from the emitter 55. The electrons are accelerated by the voltage of the anode 53 and the cathode, collide with the phosphor 56, and the phosphor emits light. The whole is protected by glass 51. The figure shows one light-emitting cell consisting of one emitter and one phosphor. Actually, however, a large number of green and red cells are arranged in addition to blue, and a display that produces various colors is constructed. The Although it does not specify in particular about the fluorescent substance used for a green or red cell, what emits high brightness | luminance with a low-speed electron beam is good to use.

  The phosphor of the present invention is a phosphor having characteristics comparable to conventional sialon phosphors and oxynitride phosphors. The phosphor of the present invention is made of a host crystal different from conventional sialon phosphors and oxynitride phosphors. Thus, if there are various phosphors, they can be appropriately selected according to the application, which is advantageous in design. In addition, the phosphor of the present invention is a nitride phosphor that is suitably used for VFD, FED, PDP, CRT, white LED, and the like, since the luminance of the phosphor is not significantly lowered when exposed to an excitation source. . In the future, it can be expected to contribute greatly to industrial development by being used in LED lighting and various display devices.

The excitation spectrum and emission spectrum by the fluorescence measurement of Example 1. The excitation spectrum and emission spectrum by the fluorescence measurement of Example 2. The excitation spectrum and emission spectrum by the fluorescence measurement of Example 3. The excitation spectrum and emission spectrum by the fluorescence measurement of Example 4. The excitation spectrum and emission spectrum by the fluorescence measurement of Example 5. The excitation spectrum and emission spectrum by the fluorescence measurement of Example 6. The excitation spectrum and emission spectrum by the fluorescence measurement of Example 7. The excitation spectrum and emission spectrum by the fluorescence measurement of Example 8. The excitation spectrum and emission spectrum by the fluorescence measurement of Example 9. The excitation spectrum and emission spectrum by the fluorescence measurement of Example 10. The excitation spectrum and emission spectrum by the fluorescence measurement of Example 11. The excitation spectrum and emission spectrum by the fluorescence measurement of Example 12. The excitation spectrum and emission spectrum by the fluorescence measurement of Example 13. The excitation spectrum and emission spectrum by the fluorescence measurement of Example 14. The excitation spectrum and emission spectrum by the fluorescence measurement of Example 15. Schematic of the lighting fixture (LED lighting fixture) by this invention. 1 is a schematic view of an image display device (field emission display) according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mixture of red phosphor and green phosphor of the present invention 2 LED chip 3, 4 Conductive terminal 5 Wire bond 6 Resin layer 7 Container 51 Glass 52 Cathode 53 Anode 54 Gate 55 Emitter 56 Phosphor 57 Electron

Claims (10)

A phosphor composed of an inorganic crystal that emits fluorescence by excitation energy from an excitation source, wherein the inorganic crystal is an RMSi ₄ N ₇ crystal (where the R element is selected from the group consisting of La, Lu, Y, and Sc) At least one element, M element is Ca and / or Mg, or a solid solution crystal thereof, and at least A element (where A element is Mn, Ce, Pr, Nd, Sm, Eu, Tb) , Dy, Er, Tm, and Yb), at least one element selected from the group consisting of Dy, Er, Tm, and Yb).   2. The phosphor according to claim 1, wherein the R element is La or Y, the M element is Ca, and the A element is Ce or Eu.   The phosphor according to claim 1, wherein the phosphor includes at least La or Y as the R element, includes at least Ca as the M element, includes at least Ce as the A element, and emits blue light by excitation light. It is characterized by emitting.   The phosphor according to claim 3, wherein the phosphor emits fluorescence having an excitation spectrum peak wavelength of 340 nm to 420 nm and an emission peak wavelength of 420 nm to 500 nm.   The phosphor according to claim 1, wherein the R element includes at least La or Y, the M element includes at least Ca, the A element includes at least Eu, and emits orange to red light by excitation light. It is characterized by.   The phosphor according to claim 5, wherein the phosphor emits fluorescence having an emission peak wavelength of 570 nm to 670 nm. The phosphor _is represented by _{A a R b M c Si d} O e N f of formula (where, a + b + c + d + e + f = 1), the parameters a, b, c, d, e, f is 0.00001 ≦ a ≦ 0.10
0.05 ≦ b ≦ 0.10
0.05 ≦ c ≦ 0.10
0.25 ≦ d ≦ 0.35
0 ≦ e ≦ 0.10
0.43 ≦ f ≦ 0.65
The phosphor according to claim 1, wherein the following condition is satisfied.   An illumination apparatus comprising an excitation source and a phosphor that emits a fluorescence phenomenon when irradiated with the excitation energy, wherein the excitation source is a light source that emits light having a wavelength of 150 to 480 nm, and at least a part of the phosphor is A lighting apparatus comprising the phosphor according to claim 1.   An image display device comprising an excitation source and a phosphor that emits a fluorescence phenomenon when irradiated with the excitation energy, wherein at least a part of the phosphor is the phosphor according to claim 1. An image display device characterized by the above.   10. The image display device according to claim 9, wherein the image display device is one of a fluorescent display tube (VFD), a field emission display (FED or SED), or a cathode ray tube (CRT), and the excitation source is an acceleration voltage. It is an electron beam of 10 V or more and 30 kV or less.