JP5187814B2 - Phosphors and light emitting devices - Google Patents

Description

The present invention relates to a phosphor having as a base crystal an SrSi ₉ Al ₁₉ O ₁ N ₃₁ (strontium-containing sialon) crystal or an inorganic crystal having the same crystal structure as SrSi ₉ Al ₁₉ O ₁ N _31, and its use. More specifically, the application relates to a lighting apparatus and a light emitting apparatus for an image display device using the property of the phosphor, that is, the characteristic of emitting light having a peak at a wavelength of 420 nm to 500 nm.

  The phosphor is a fluorescent display tube (VFD (Vacuum-Fluorescent Display)), a field emission display (FED (Field Emission Display)), or a SED (Surface-Condition Electron display-Pl (Panel 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 exposure of the phosphor 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 has no luminance reduction. For this reason, sialon phosphors and oxynitride phosphors are used as phosphors with little reduction in luminance instead of conventional phosphors such as silicate phosphors, phosphate phosphors, aluminate phosphors, and sulfide phosphors. In addition, phosphors based on inorganic crystals containing nitrogen in the crystal structure, such as nitride phosphors, have been proposed.

An example of this 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). And is fired by a hot press method (for example, see 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 the composition and structure of SrSi ₉ Al ₁₉ O ₁ N ₃₁ crystal, which is a sialon containing Sr.

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 J. et al. Grins, et al., “High-resolution Electron Microscopy of a Sr-Containing Sialon Polytype Poise”, Journal of the European Ceramics, 19-27, 19-27.

  For applications such as white LEDs and plasma displays using ultraviolet LEDs as excitation sources, purple, blue and green phosphors are required in addition to red and yellow as phosphors having excellent durability and high luminance. Yes. Furthermore, conventional phosphors using oxynitride as a host are insulating materials, and even when irradiated with an electron beam, the emission intensity is low. There is a need for phosphors that emit light with high brightness.

  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.

  The object of the present invention is to respond to such a demand, and is a phosphor superior in emission characteristics than a conventional rare earth activated sialon phosphor, and more durable than a conventional oxide phosphor, Above all, it is intended to provide purple, blue and green phosphor powders. Furthermore, it is intended to provide purple, blue and green phosphor powders that emit light efficiently with an electron beam.

  As a result of intensive research under such circumstances, the present inventor succeeded in providing a phosphor exhibiting a high-luminance light emission phenomenon in a specific wavelength region, a lighting fixture having excellent characteristics, and an image display device. did. The details will be described below.

The phosphor of the present invention is SrSi ₉ Al ₁₉ O ₁ N ₃₁ Crystal or SrSi ₉ Al ₁₉ O ₁ N ₃₁ Ce and Li are solid-dissolved in inorganic crystals having the same crystal structure.
The inorganic crystal is (Sr _1-2y Ce _y Li _y ) Si _10-x Al _{18 + x} O _x N _32-x And the parameters x and y are
0 ≦ x ≦ 2 (i)
0.00001 ≦ y ≦ 1 (ii)
The above conditions may be satisfied.
The luminaire of the present invention is composed of a light-emitting light source that emits light having a wavelength of 250 to 400 nm and a phosphor that uses this as excitation light, and at least a part of the phosphor is the above-described phosphor. And
The light-emitting light source is an LED or LD, and the phosphor described above may emit blue light having an emission peak at a wavelength of 420 nm to 500 nm by excitation light of 250 to 400 nm.
An image display device according to the present invention includes a phosphor and an excitation source that excites the phosphor, and at least a part of the phosphor is the above-described phosphor.
The excitation source may be an electron beam having an acceleration voltage of 10 V or more and 30 kV or less.
The image display device can be either a fluorescent display tube (VFD), a field emission display (FED or SED), or a cathode ray tube (CRT).

The phosphor of the present invention contains, as a main component, an SrSi ₉ Al ₁₉ O ₁ N ₃₁ crystal in which a metal ion serving as an emission center is dissolved or an inorganic substance having the same crystal structure as SrSi ₉ Al ₁₉ O ₁ N _31. Therefore, the emission intensity at 420 nm to 500 nm is higher than that of conventional sialon and oxynitride phosphors, and it is excellent as a purple, blue, and green phosphor for use in white LEDs. Even when the phosphor is exposed to an excitation source, the luminance of the phosphor hardly decreases. Furthermore, 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.

The present _invention focuses on SrSi ₉ Al ₁₉ O _{1 N 31 crystal,} SrSi ₉ Al ₁₉ O _{1 N 31} crystal, or SrSi ₉ Al ₁₉ O ₁ N ₃₁ inorganic crystal having the same crystal structure and, at least Ce As a result of intensive research on solid-state inorganic crystals, blue fluorescence having a specific composition region range, a specific solid-solution state, and a specific crystal phase has an emission peak at a wavelength in the range of 420 nm to 500 nm. I found it to be a body. Among them, those with a specific composition range in which Li is dissolved in addition to Ce emit light of purple to blue with high brightness by ultraviolet ray or electron beam excitation, and are used for illumination or image display excited by an electron beam. It has been found that it is suitable for the device.

According to Non-Patent Document 1, the crystal structure and composition of the SrSi ₉ Al ₁₉ O ₁ N ₃₁ crystal have been clarified by electron microscope observation. However, there is no description about a phosphor obtained by adding Ce to this crystal. As a result of research as a part, the present invention has been obtained.

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

The phosphor of the present invention contains SrSi ₉ Al ₁₉ O ₁ N ₃₁ crystal or an inorganic crystal having the same crystal structure as SrSi ₉ Al ₁₉ O ₁ N ₃₁ as a main component. The SrSi ₉ Al ₁₉ O ₁ N ₃₁ crystal is a Sr-containing sialon crystal having a layered structure as described in Non-Patent Document 1. This crystal is synthesized by mixing AlN, Si ₃ N ₄ , and SrCO ₃ and firing at 1800 ° C. _Further, the inorganic crystal having the same crystal structure as _{SrSi 9 Al 19 O 1 N 31} , while the oxygen / nitrogen ratio was kept crystal structure changes or the _{SrSi 9 Al 19 O 1 N 31} , the other elements Added crystals. Examples of addition of other elements include those containing Mg, Ca, Ba, and Li. 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 SrSi ₉ Al ₁₉ O ₁ N ₃₁ crystal can be identified by X-ray diffraction or neutron diffraction. The details of the crystal structure are described in Non-Patent Document 1, and the crystal structure and X-ray diffraction pattern are uniquely determined from the lattice constant, space group, and atomic position data described therein. In addition to pure SrSi ₉ Al ₁₉ O ₁ N ₃₁ crystal, a crystal whose lattice constant is changed by replacing a constituent element with another element is also included as part of the present invention.

In the present invention, SrSi ₉ Al ₁₉ O ₁ N ₃₁ crystal or an inorganic crystal having the same crystal structure as SrSi ₉ Al ₁₉ O ₁ N ₃₁ is used as a base crystal, and optically active Ce is dissolved therein. The phosphor has excellent optical properties.

Further, Li in a solid solution exhibits excellent light emission characteristics. Since Li is a monovalent element, when Li is dissolved, electrical neutrality is maintained, so that Ce ³⁺ that is a trivalent ion can stably exist in the crystal. Ions are easily taken into the crystal. Thereby, it is thought that it has contributed to the brightness improvement of fluorescent substance.

One of the phosphor composition of the present _invention, represented by _{(Sr 1-2y Ce y Li y)} Si 10-x Al 18 + x O x N 32-x, parameter x, y is, 0 ≦ x ≦ 2, and There is a phosphor having a composition range selected from values satisfying the condition of 0.00001 ≦ y ≦ 1.

  Here, x is a parameter that determines the ratio of Si and Al forming the skeleton of the crystal structure, and by changing this value, the excitation and emission wavelengths change, so select a value that suits the application within this range. Can do. y is a parameter that determines the amount of Ce, which is a luminescent ion. If it is less than 0.00001, sufficient light emission cannot be obtained, and if it is greater than 1, concentration quenching occurs due to interference between ions, and the luminance may decrease. There is.

  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 250 nm or more and 400 nm or less, it is preferable for white LED applications. 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 at a wavelength in the range of 420 nm to 500 nm is emitted, and the emitted color differs depending on the additive element.

  The excitation source is efficiently excited by ultraviolet rays, electron beams, X-rays, and the like. In the case of excitation with ultraviolet light, excitation is particularly efficient at wavelengths in the range of 250 nm to 400 nm. Since this phosphor emits light at a wavelength of 253.7 nm emitted from vacuum ultraviolet rays or mercury atoms, it is suitable for use in plasma displays, fluorescent lamps, and mercury lamps.

In the present invention, from the viewpoint of fluorescence emission, SrSi ₉ Al ₁₉ O ₁ N ₃₁ crystal, which is a constituent component, or inorganic crystals having the same crystal structure as SrSi ₉ Al ₁₉ O ₁ N ₃₁ are highly purified and have as much as possible. If possible, it is preferably composed of a single phase, but it can also be composed of a mixture with other crystalline phase or amorphous phase as long as the characteristics are not deteriorated. In this case, the content of SrSi ₉ Al ₁₉ O ₁ N ₃₁ crystals or inorganic crystals having the same crystal structure as SrSi ₉ Al ₁₉ O ₁ N ₃₁ is 10% by mass or more, more preferably 50% by mass or more. Is desirable to obtain high brightness. In the present invention, the main component is such that the content of SrSi ₉ Al ₁₉ O ₁ N ₃₁ crystals or inorganic crystals having the same crystal structure as SrSi ₉ Al ₁₉ O ₁ N ₃₁ is at least 10% by mass. The ratio of the content is measured by X-ray diffraction, and Rietveld analysis of the SrSi ₉ Al ₁₉ O ₁ N ₃₁ crystal, or the inorganic crystal having the same crystal structure as SrSi ₉ Al ₁₉ O ₁ N ₃₁ and the other crystal phase It can be obtained by doing. Briefly, for the SrSi ₉ Al ₁₉ O ₁ N ₃₁ crystal, or the inorganic crystal having the same crystal structure as SrSi ₉ Al ₁₉ O ₁ N ₃₁ and other crystal phases, the strength of the strongest peak of each phase It can be obtained from the ratio.

  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 purple and blue, but if it is necessary to mix with other colors such as yellow and red, inorganic phosphors that develop these colors can be mixed as necessary. . Other inorganic phosphors that can be used include oxides, sulfides, oxysulfides, oxynitrides, and nitride crystals as hosts, but the durability of the mixed phosphor is required. In this case, it is preferable to use oxynitride or nitride crystal 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 (a part of CaAlSiN ₃ crystal is replaced by 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 : Ce blue phosphor, AlN: Eu blue phosphor, 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.

A metal containing Ce, oxide, carbonate, nitride, fluoride, chloride, oxynitride or a combination thereof, a raw material containing silicon, and a raw material containing aluminum are prepared. Furthermore, a metal, an oxide, a carbonate, a nitride, a fluoride, a chloride, an oxynitride, or a combination thereof containing an element that dissolves in the present crystal such as Li can be added as necessary. The raw material mixture 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 15 × 10 ² ° C to 22 × 10 ² ° C in a nitrogen atmosphere of 0.1 MPa to 100 MPa. By doing so, the fluorescence of the present invention is obtained by dissolving at least Ce in an SrSi ₉ Al ₁₉ O ₁ N ₃₁ crystal or an inorganic crystal having the same crystal structure as SrSi ₉ Al ₁₉ O ₁ N _31. The body can be manufactured. The optimum firing temperature may vary depending on the composition, and can be optimized as appropriate. In general, it is preferable to fire in a temperature range of 17 × 10 ² ° C or higher and 20 × 10 ² ° C or lower. In this way, a high-luminance phosphor can be obtained. When the firing temperature is lower than 15 × 10 ² ° C., the production rate of SrSi ₉ Al ₁₉ O ₁ N ₃₁ crystals or inorganic crystals having the same crystal structure as SrSi ₉ Al ₁₉ O ₁ N ₃₁ may be low. In addition, when the firing temperature is 22 × 10 ² ° C. or higher, 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, and the like 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, and fluoride, chloride, iodide, bromide, or phosphorus of Li, Na, K, Mg, Ca, Sr, Ba, and Al elements. Acid salts 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. The amount of the inorganic compound added is not particularly limited, but the effect is particularly large when it is 1 × 10 ⁻³ parts by weight to 1 × 10 ⁻¹ parts by weight with respect to 1 part by weight of the mixture of the metal compound as the starting material. If the amount is less than 1 × 10 ⁻³ parts by weight, the reactivity is not improved, and if it exceeds 1 × 10 ⁻¹ 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 1 × 10 ⁻¹ MPa to 1 × 10 ² MPa. More preferably, it is 5 × 10 ⁻¹ MPa or more and 10 MPa or less. When silicon nitride is used as a raw material, heating to a temperature of 1820 ° C. or higher in a nitrogen gas atmosphere lower than 1 × 10 ⁻¹ MPa is not preferable because the raw material is likely to be thermally decomposed. If it is higher than 5 × 10 ⁻¹ MPa, it hardly decomposes. 10 MPa is sufficient, and if it is 1 × 10 ² MPa or more, a special apparatus is required, which is not suitable for industrial production.

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 relative bulk density is maintained at a filling rate of 40% or less (2/5). 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. Are filled at a filling rate 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 a shape of 5 × 10 ² μm or less using a spray dryer or the like. 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% or less (2/5) is that firing is performed with 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. When 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 forming a light emitting device in combination with the light emitting element. When the thickness is 20 nm or less, 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 higher and lower 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 purple and blue light, and is suitable for lighting equipment and image display devices. 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. In LED lighting fixtures, the phosphor of the present invention is used to manufacture 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 an ultraviolet LED or LD light emitting device of 330 to 400 nm, a yellow phosphor having an emission peak at a wavelength of 550 nm to 600 nm and excited by this wavelength, and the blue phosphor of the present invention. 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: Ce can be mentioned. In this configuration, when the phosphors are irradiated with ultraviolet rays emitted from the LED or LD, light of two colors, blue and yellow, is emitted, and a white luminaire is obtained by mixing them.

As another example, an ultraviolet LED or LD light emitting device of 330 to 400 nm, a green phosphor excited at this wavelength and having an emission peak at a wavelength of 520 nm or more and 550 nm or less, and a red having an emission peak at a wavelength of 600 nm or more and 700 nm or less There is a combination of a phosphor and the blue phosphor of the present invention. Examples of such green phosphor include β-sialon: Eu ²⁺ described in JP-A-2005-255895, and examples of red phosphor include CaSiAlN ₃ : Eu ²⁺ described in International Publication No. 2005/052087. be able to. In this configuration, when the phosphors are irradiated with ultraviolet rays emitted from the LED or LD, light of three colors of red, green, and blue is emitted, and a white lighting device is obtained by mixing these.

As another method, an ultraviolet LED or LD light emitting device of 330 to 400 nm, a green phosphor excited at this wavelength and having an emission peak at a wavelength of 520 to 550 nm, and a wavelength of 550 to 600 nm excited at this wavelength. There is a combination of a yellow phosphor having a light emission peak, a red phosphor having an emission peak at a wavelength of 600 nm to 700 nm when excited at this wavelength, and the phosphor of the present invention. As such a green phosphor, β-sialon: Eu ²⁺ described in JP-A-2005-255895 is used. As such a yellow phosphor, α-sialon: Eu ²⁺ described in JP-A-2002-363554 is used. (Y, Gd) ₂ (Al, Ga) ₅ O ₁₂ : Ce described in JP-A-9-218149 and CaSiAlN described in WO 2005/052087 pamphlet as such a red phosphor. ₃ : Eu can be mentioned. 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 1-9>
The raw material powder is an aluminum nitride powder (F grade made by Tokuyama) with a specific surface area of 3.3 m ² / g and an oxygen content of 0.79%, an average particle size of 0.5 μm, an oxygen content of 0.93% by weight, and α-type content 92% silicon nitride powder (E10 grade manufactured by Ube Industries), 99.9% pure strontium carbonate powder (high purity chemical reagent grade), 99.9% pure lithium carbonate powder (high purity chemical reagent) Grade), and cerium oxide powder (manufactured by Shin-Etsu Chemical Co., Ltd.) having a purity of 99.9%.

Next, a phosphor containing metal elements Ce and Li was synthesized. Table 1 summarizes the design compositions of Examples 1-9. In order to obtain the design composition represented by parameters x and y shown in Table 1, the raw material powder is weighed at the mass ratio shown in Table 1 and mixed using a mortar and pestle made of a silicon nitride sintered body. By passing through a 125 μm sieve, a powder aggregate having excellent fluidity was obtained. When this powder aggregate was naturally dropped into a boron nitride crucible having a diameter of 20 mm and a height of 20 mm, the bulk density was 15 to 30% by volume. The bulk density was calculated from the weight of the charged powder aggregate, the inner volume of the crucible, and the true density of the powder. 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, and nitrogen having a purity of 99.9995 vol% is introduced at 800 ° C. to a gas pressure of 1 MPa. The temperature was raised to 1900 ° C. at 500 ° C./hour and held at 1900 ° C. for 4 hours. When the synthesized sample was ground with a mortar and pestle made of silicon nitride, was conducted a powder X-ray diffraction measurement using a K _alpha line of Cu _{(XRD), SrSi 9 Al 19} O 1 N 31 crystal, or SrSi Inorganic crystals having the same crystal structure as ₉ Al ₁₉ O ₁ N ₃₁ were confirmed. Depending on the composition, phases other than SrSi ₉ Al ₁₉ O ₁ N ₃₁ crystals or inorganic crystals having the same crystal structure as SrSi ₉ Al ₁₉ O ₁ N ₃₁ were detected. The production ratio of ₉ Al ₁₉ O ₁ N ₃₁ crystals or inorganic crystals having the same crystal structure as SrSi ₉ Al ₁₉ O ₁ N ₃₁ was determined 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 from purple to blue. The emission spectrum and excitation spectrum of this powder were measured using a fluorescence spectrophotometer. Example 1 in FIG. 1, Example 2 in FIG. 2, Example 3 in FIG. 3, Example 5 in FIG. 4, Example 7 in FIG. 5, Example 8 in FIG. The results of peak emission wavelength and fluorescence emission intensity are summarized. These powders have an excitation spectrum peak at a wavelength in the range of 300 to 400 nm, and are phosphors that emit light having an emission spectrum peak at a wavelength in the range of 400 to 500 nm upon excitation at the peak wavelength of the excitation spectrum. I understood that. 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.

  FIG. 7 shows the relationship between Ce concentration and emission intensity. The emission intensity is strong at a Ce concentration of 20% (y value is 0.2).

  Regarding Example 1, 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. This phosphor was excited by an electron beam. It was confirmed that blue light was emitted.

Next, a lighting fixture using the phosphor of the present invention will be described. FIG. 8 shows a schematic structural diagram of a white LED as a lighting fixture. The phosphor mixture made of the nitride of the present invention and other phosphors are used, and a 380 nm ultraviolet LED chip 2 is used as the light emitting element. The blue phosphor of Example 1 of the present invention and Ca-α-sialon having a composition of Ca _0.75 Eu _0.25 Si _8.625 A1 _3.375 O _1.125 N _14.875 : Yellow fluorescence of Eu The mixture phosphor 1 in which the body and the red phosphor of CaAlSiN ₃ : Eu are dispersed in the resin layer is placed on the LED chip 2 and disposed in the container 7. 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 is a mixture of a green phosphor, a yellow phosphor and a red phosphor. The phosphor 1 is excited to emit blue, yellow, and red light, respectively, and these lights are mixed to function as an illumination device that emits white light.

  FIG. 9 is a schematic diagram showing the principle 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 nitride phosphor of the present invention emits blue light different from that of conventional sialon, and further, there is little decrease in the brightness of the phosphor when exposed to an excitation source. Therefore, VFD, FED, PDP, CRT, white LED Nitride phosphors that are preferably used for the above. In the future, it is expected to contribute greatly to industrial development by being widely used in various electron beam excitation 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 5. 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. Relationship between Ce concentration and emission intensity. 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 blue phosphor and yellow phosphor of the present invention, or mixture of blue phosphor, 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 (7)

A phosphor characterized in that Ce and Li are dissolved in an SrSi ₉ Al ₁₉ O ₁ N ₃₁ crystal or an inorganic crystal having the same crystal structure as SrSi ₉ Al ₁₉ O ₁ N ₃₁ . Wherein the inorganic crystals _is indicated by _{(Sr 1-2y Ce y Li y)} Si 10-x Al 18 + x O x N 32-x, parameter x, y is
0 ≦ x ≦ 2 (i)
0.00001 ≦ y ≦ 1 (ii)
The phosphor according to claim 1, wherein the above condition is satisfied. It is the lighting fixture comprised from the light emission light source which emits the light of the wavelength of 250-400 nm, and the fluorescent substance which uses this as excitation light, Comprising: At least one part of the said fluorescent substance is in any one of Claim 1 or 2 A lighting apparatus comprising the phosphor according to the description. The light emitting source is an LED or an LD, and the phosphor according to claim 1 emits blue light having an emission peak at a wavelength of 420 nm to 500 nm by excitation light of 250 to 400 nm. The lighting fixture according to claim 3 . An image display device comprising a phosphor and an excitation source for exciting the phosphor, wherein at least a part of the phosphor is the phosphor according to claim 1 or 2. Image display device. The image display apparatus according to claim 5, wherein the excitation source is an electron beam having an acceleration voltage of 10 V to 30 kV. 7. The image display device according to claim 6, wherein the image display device is a fluorescent display tube (VFD), a field emission display (FED or SED), or a cathode ray tube (CRT).