JP2006312662A - Europium-activated yttrium borate phosphor and plasma display panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a europium-activated yttrium borate phosphor with an improved light emission luminance, a shortened afterglow time, or an improved color purity and to provide a plasma display panel using the phosphor. <P>SOLUTION: The europium-activated yttrium borate phosphate phosphor is characterized in that the standard deviation (σ) of the average europium content in the surface of each particle is in the range: 0≤σ≤10. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a europium activated yttrium borate phosphor and a plasma display panel using the same.

In a plasma display panel (hereinafter referred to as PDP), a phosphor layer is provided in a large number of cells formed by two glass substrates provided with electrodes and a partition provided between the substrates. When a voltage is applied between the electrodes to discharge the cell, ultraviolet rays are generated due to the discharge gas sealed in the cell, thereby exciting the phosphor and emitting visible light. Currently used as phosphors for PDP are (Y, Gd) BO ₃ : Eu (red), Zn ₂ SiO ₄ : Mn (green), BaMgAl ₁₀ O ₁₇ : Eu (blue), etc. There is.

A display such as a PDP is required to have improved brightness, smooth moving image display, color purity, and the like. As one of means for increasing the luminance, there is a demand for improvement of the emission luminance of the phosphor. In particular, in the case of PDP, neon is used as the discharge gas, and therefore, orange light emission around 585 nm peculiar to neon is strongly emitted in addition to the phosphor light emission. Also, (Y, Gd) BO ₃ : Eu itself has a slightly orange hue, and it is necessary to provide a front filter in order to improve the color purity by suppressing these emissions. Therefore, the red phosphor is required to further improve the luminance.

On the other hand, in order to display a smooth moving image, information must be displayed one after another at an extremely short unit time. Conventionally, the afterglow time of green phosphors such as Zn ₂ SiO ₄ : Mn is long, and there have been problems such as afterimages and flickering of images that occur when the next new information is displayed. However, with respect to the green phosphor, significant improvement has been seen due to the progress of technology, and recently, the afterglow time of the red phosphor has become a new issue. As described above, red phosphors are required to improve emission luminance and shorten afterglow time.

For a plasma display having red and green phosphor layers with a short afterglow time, the red phosphor layers are (Y, Gd) BO ₃ : Eu and Y ₂ O ₃ : Eu, (Y, Gd) (P, V) Although there is a description (for example, refer to Patent Document 1) that a short afterglow is achieved by mixing one or more phosphors of O ₄ : Eu, short afterglow is achieved by carrying out this method. In general, Y ₂ O ₃ : Eu, (Y, Gd) (P, V) O ₄ : Eu, etc. satisfy the various characteristics required for plasma display because phosphor deterioration due to vacuum ultraviolet irradiation is large. I couldn't say.

Description of the effect that the activator present on the particle surface causes deterioration due to irradiation with vacuum ultraviolet rays for a plasma display panel having a phosphor having a smaller amount of activator on the particle surface than the amount of activator inside the particle (see, for example, Patent Document 2). In general, however, it is known that (Y, Gd) BO ₃ : Eu is hardly deteriorated by irradiation with vacuum ultraviolet rays, and the emission luminance is not sufficient.
Japanese Patent Laid-Open No. 2003-142005 JP 2004-91622 A

  The present invention has been made in view of the above problems, and an object of the present invention is to use a europium-activated yttrium borate phosphor with improved light emission luminance and afterglow time, or improved color purity, and the phosphor. It is to provide a plasma display panel.

  The above object of the present invention can be achieved by the following constitution.

(Claim 1)
A europium-activated yttrium borate-based phosphor, wherein the standard deviation (σ) of the average europium content on the surface of each particle is 0 ≦ σ ≦ 10.

(Claim 2)
The europium-activated yttrium borate phosphor according to claim 1, wherein the average europium content on the particle surface is higher than that in the particle.

(Claim 3)
The europium-activated yttrium borate phosphor according to claim 1, wherein the average europium content in the particles is 50 mol% or more and 99 mol% or less of the average europium content on the particle surface.

(Claim 4)
A plasma display panel comprising the europium-activated yttrium borate phosphor according to claim 1.

  According to the present invention, it is possible to provide a europium-activated yttrium borate-based phosphor having improved light emission luminance and reduced afterglow time, or improved color purity, and a plasma display panel using the phosphor.

  Hereinafter, although the best mode for carrying out the present invention will be described, the present invention is not limited to these.

  The europium-activated yttrium borate phosphor particles of the present invention are characterized in that the standard deviation (σ) of the average europium content on the surface of each particle is 0 ≦ σ ≦ 10. Furthermore, 0 ≦ σ ≦ 5 is preferable, and 0 ≦ σ ≦ 2 is more preferable. If particles containing europium are present, problems such as concentration quenching and long afterglow time tend to be caused, and desired characteristics cannot be obtained.

  In the present invention, the particle surface means a range from the particle outermost surface to a depth of 10 nm.

  In the present invention, the average europium content and standard deviation (σ) on the surface of the phosphor particles were confirmed by X-ray photoelectron spectroscopy.

  X-ray photoelectron spectroscopy is a method of analyzing the kinetic energy of photoelectrons emitted from the surface by irradiating the sample with monochromatic X-rays, and is an element present at a depth of several to several tens of nanometers on the sample surface. The composition can be qualitative and quantitative. In addition, each element's spectrum is affected by neighboring elements, and chemical shifts, satellites based on charge transfer transitions, splitting of the inner shell rank due to multiplet bonds, etc. appear. Information is obtained.

  The europium-activated yttrium borate phosphor particles of the present invention preferably have a higher europium average content on the particle surface than in the particles. Specifically, the average europium content in the particles is preferably 50 mol% or more and 99 mol% or less, more preferably 60 mol% or more and 90 mol% or less of the average europium content on the particle surface, Most preferably, it is 70 mol% or more and 80 mol% or less. When the average europium content in the particles is less than 50 mol% of the average europium content on the particle surface, the crystallinity of the particles is deteriorated and desired characteristics cannot be obtained.

  In the present invention, the europium composition inside the phosphor particles was confirmed by inductively coupled plasma emission spectroscopy.

  Inductively coupled plasma emission spectroscopy is a method in which a sample is introduced into an argon plasma at a high temperature and the light specific to each element generated is measured. The intensity of the light is proportional to the amount of elements in the sample. High-sensitivity qualitative and quantitative analysis of samples is possible. Because of the high temperature of the plasma, the optimum measurement conditions for most elements are almost the same, and simultaneous multi-element analysis and multi-element sequential analysis are possible.

  Embodiments of a europium-activated yttrium borate phosphor and a plasma display panel (PDP) according to the present invention will be described below with reference to the drawings.

  The europium-activated yttrium borate phosphor of the present invention is not particularly limited, and can be produced using a known method. In order to precisely control the composition of the phosphor, a liquid phase synthesis method is used. It is particularly preferable to make them.

  The liquid phase synthesis method refers to a precursor forming step in which phosphor raw materials are mixed in a liquid phase to form a precursor, and a firing step in which the obtained precursor is fired to obtain a phosphor. The precursor is an intermediate compound of a phosphor to be manufactured, and is a compound that becomes a phosphor by firing treatment as described above.

For the precursor forming step, a coprecipitation method, a reaction crystallization method, a sol-gel method, or the like is preferably used. In (Y, Gd) BO ₃ : Eu, it is preferable to form a precursor by a reaction crystallization method. The reaction crystallization method refers to a method in which a solution containing an element as a phosphor raw material is mixed and a phosphor precursor crystal is precipitated by reaction in the solution.

  In a particularly preferred embodiment, a solution A containing an yttrium compound, a gadolinium compound, and a europium compound and a boric acid solution B are mixed in a reaction vessel filled with a specific solvent C. At this time, a precipitant is added to precipitate a europium-activated yttrium borate phosphor precursor having a uniform particle surface composition. Examples of the control factor for controlling the standard deviation (σ) of the europium content on the particle surface include the raw material concentration, the addition method, the reaction temperature, the stirring speed, and the pH.

  Further, in order to control the europium concentration on the particle surface, solution A, solution B, and precipitating agent whose raw material concentrations are adjusted in the precursor dispersion prepared in advance are further mixed to control the europium concentration on the precursor particle surface. .

  At this time, the solution A, solution B, and the precipitating agent having adjusted raw material concentrations are further mixed in a dispersion obtained by adding phosphor particles prepared in advance to the solvent C to control the europium concentration on the surface of the precursor particles. It is also a preferred embodiment.

  The solution A and the solution B are preferably various metal compounds such as chlorides and nitrates, and are preferably dissolved in a cation state in a solvent.

  The solvent is preferably water or alcohols or a mixture thereof. Examples of alcohols include methanol, ethanol, isopropanol, propanol, butanol and the like. In particular, ethanol is preferable.

  As the precipitant, an organic acid or an alkali hydroxide can be preferably used. Organic acids or alkali hydroxides react with metallic elements to form organic acid salts or hydroxides as precipitates. As the organic acid, those having a carboxylic acid group (—COOH) are preferable, and specific examples include oxalic acid, formic acid, acetic acid, tartaric acid and the like. Moreover, oxalic acid, formic acid, acetic acid, tartaric acid, etc. may be produced by hydrolysis or the like.

  Any alkali hydroxide may be used as long as it has a hydroxyl group (—OH), or can react with water to form a hydroxyl group or generate a hydroxyl group by hydrolysis, such as ammonia or sodium hydroxide. , Potassium hydroxide, urea and the like. Among these, ammonia is preferably used, and particularly preferably ammonia containing no alkali metal.

  In the present invention, the prepared precursor is filtered and dried using an appropriate means such as centrifugation. Thereafter, firing is performed in a specific atmosphere to produce a phosphor. At this time, as a preferred embodiment, firing in an oxidizing atmosphere (for example, nitrogen-oxygen (21%)) is performed in the range of 1000 ° C to 1400 ° C. Furthermore, the europium concentration on the particle surface can be controlled to a desired concentration by appropriately changing the firing atmosphere, time, temperature, number of firings, and the like. For example, a method in which an oxidizing atmosphere (for example, nitrogen-oxygen (21%)) is fired in a high temperature range near 1200 to 1400 ° C., and then an inert atmosphere firing is performed in a low temperature range near 800 to 1000 ° C. is preferable. It is one of.

  Moreover, it is preferable that the phosphor obtained by firing is washed with an acid and then dried. By the acid cleaning, the emission luminance is considered to be improved due to changes in the particle surface state and dissolution of impurities introduced in the baking process. Although there is no restriction | limiting in particular about the kind of acid, Mineral acids, such as hydrochloric acid, nitric acid, a sulfuric acid, are mentioned. Also formic acid, acetic acid, butyric acid, palmitic acid, stearic acid, acrylic acid, methacrylic acid, oleic acid, linoleic acid, linolenic acid, oxalic acid, adipic acid, maleic acid, fumaric acid, lactic acid, malic acid, tartaric acid, benzoic acid Carboxylic acids such as salicylic acid, phthalic acid, propionic acid, isobutyric acid, valeric acid, pivalic acid, lauric acid, myristylic acid, propiolic acid and crotonic acid are also effective. Although the acid concentration, washing time, temperature, etc. depend on the phosphor preparation method, it is preferable to stir and wash at about 0.01 to 1 N for 5 to 60 minutes and to treat at around 20 to 30 ° C.

(PDP structure)
Hereinafter, a plasma display panel according to the present invention will be described with reference to FIG. The PDP can be broadly classified from the electrode structure and operation mode into a DC type that applies a DC voltage and an AC type that applies an AC voltage. FIG. 1 shows the configuration of the AC PDP. A schematic example is shown.

  A PDP 1 shown in FIG. 1 is divided into a predetermined shape by two substrates 10 and 20 provided with electrodes 11 and 21, a partition 30 provided between the substrates 10 and 20, and the partition 30. It has a plurality of micro discharge spaces (hereinafter referred to as discharge cells) 31. The discharge cell 31 shown in FIG. 1 is a so-called stripe type. When the substrates 10 and 20 are horizontally arranged, the partition walls 30 are provided in parallel at predetermined intervals (that is, in a stripe shape). It is. Each discharge cell 31R, 31G, 31B is provided with phosphor layers 35R, 35G, 35B made of a phosphor that emits light in any of red (R), green (G), and blue (B). Further, inside each discharge cell 31, a discharge gas is sealed, and at least one point where the electrodes 11 and 21 intersect in a plan view is provided.

  Hereinafter, each component of PDP1 is demonstrated.

  First, of the two substrates, the configuration on the front plate 10 side arranged on the display side will be described. The front plate 10 transmits visible light emitted from the discharge cells 31 and displays various information on the substrate, and functions as a display screen of the PDP 1.

  A material that transmits visible light, such as soda lime glass (blue plate glass), can be preferably used as the front plate 10. The thickness of the front plate 10 is preferably in the range of 1 to 8 mm, more preferably 2 mm. The front plate 10 is provided with a display electrode 11, a dielectric layer 12, a protective layer 13, and the like.

  A plurality of display electrodes 11 are provided on the surface of the front plate 10 facing the back plate 20 and are regularly arranged. The display electrode 11 includes a transparent electrode 11a and a bus electrode 11b, and has a structure in which a bus electrode 11b similarly formed in a strip shape is laminated on a transparent electrode 11a formed in a wide strip shape. The width of the bus electrode 11b is narrower than that of the transparent electrode 11a. Further, the display electrode 11 is orthogonal to the partition wall 30 in plan view. The display electrode 11 is a set of two display electrodes 11 that are arranged to face each other with a predetermined discharge gap. Visible light can be generated from the phosphor layers 35R, 35G, and 35B by performing plasma discharge between the pair of display electrodes 11 and 11.

  A transparent electrode such as a nesa film can be used as the transparent electrode 11a, and the sheet resistance is preferably 100Ω or less. The width of the transparent electrode 7 is preferably in the range of 10 to 200 μm.

  The bus electrode 11b is for lowering the resistance and can be formed by sputtering of Cr / Cu / Cr or the like. The width of the bus electrode 11b is preferably in the range of 5 to 50 μm.

  The dielectric layer 12 covers the entire surface of the front plate 10 on which the display electrodes 11 are disposed. The dielectric layer 12 can be formed of a dielectric material such as low-melting glass. The thickness of the dielectric layer 12 is preferably in the range of 20 to 30 μm. The surface of the dielectric layer 12 is entirely covered with the protective layer 13. The protective layer 13 can use an MgO film. As thickness of the protective layer 13, the range of 0.5-50 micrometers is preferable.

  Next, the configuration on the back plate 20 side which is the other of the two substrates 10 and 20 will be described.

  The back plate 20 is provided with address electrodes 21, dielectric layers 22, partition walls 30, phosphor layers 35R, 35G, and 35B.

  As the back plate 20, soda lime glass (blue plate glass) or the like can be used similarly to the front plate 10. As thickness of the backplate 20, the range of 1-8 mm is preferable, More preferably, it is about 2 mm. A plurality of the address electrodes 21 are provided on the surface of the back plate 20 facing the front plate 20. The address electrode 21 is also formed in a strip shape like the transparent electrode 11a and the bus electrode 11b. A plurality of address electrodes 21 are provided at predetermined intervals so as to be orthogonal to the display electrodes 11 in plan view. The address electrode 21 can be a metal electrode such as an Ag thick film electrode. The width of the address electrode 21 is preferably in the range of 100 to 200 μm. The dielectric layer 22 covers the entire surface of the back plate 20 on which the address electrodes 21 are disposed. The dielectric layer 22 can be formed of a dielectric material such as low melting glass. The thickness of the dielectric layer 22 is preferably in the range of 20 to 30 μm. The partition wall 30 is provided on the dielectric layer 22 so as to protrude from the back plate 20 side to the front plate 10 side. The barrier ribs 30 are formed long and are provided on both sides of the address electrode 21, and as described above, the discharge cells 31 are formed in stripes in a plan view. The partition wall 30 can be formed of a dielectric material such as low-melting glass. The width of the partition wall 30 is preferably in the range of 10 to 500 μm, and more preferably about 100 μm. The height (thickness) of the partition wall 30 is usually in the range of 10 to 100 μm, and preferably about 50 μm. As described above, any one of the phosphor layers 35R, 35G, and 35B that emit light of each color is provided in the discharge cell 31 in a regular order.

Among the phosphor layers 35R, 35G, and 35B, the phosphor layer 35R that emits red light is represented by the europium-activated yttrium borate phosphor according to the present invention, preferably (Y, Gd) BO ₃ : Eu. It is a phosphor. The phosphors constituting the phosphor layers 35G and 35B that emit green or blue light are not particularly limited, but as the phosphor used for the phosphor layer 35G that emits green light, for example, the composition formula is Zn. Those represented by ₂ SiO ₄ : Mn can be preferably used. Further, as the phosphor used for the phosphor layer 35B that emits blue light, for example, those whose composition formula is represented by BaMgAl ₁₀ O ₁₇ : Eu can be preferably used. The thickness of each of the phosphor layers 35R, 35G, and 35B is not particularly limited, but is preferably in the range of 0.5 to 10 μm.

  In forming the phosphor layer 35R, the europium-activated yttrium borate phosphor produced above is dispersed in a mixture of a binder, a solvent, a dispersant, etc., and a phosphor paste adjusted to an appropriate viscosity is applied to the discharge cell 31. The phosphor layer 35R in which the europium-activated yttrium borate phosphor is adhered to the partition wall side surface 30a and the bottom surface 30a is formed by coating or filling, and then drying or firing. The content of the europium activated yttrium borate phosphor in the phosphor paste is preferably in the range of 30% by mass to 60% by mass.

Examples of the binder suitable for dispersing the europium-activated yttrium borate-based phosphor particles favorably include ethyl cellulose and polyethylene oxide (ethylene oxide polymer), and in particular, an average content of ethoxy groups (—OC ₂ H ₅ ). It is preferable to use ethyl cellulose having a rate of 49 to 54%. A photosensitive resin can also be used as the binder. The binder content is preferably in the range of 0.15% by mass to 10% by mass. In addition, in order to adjust the shape of the phosphor paste applied between the barrier ribs 30, it is preferable to set the binder content to a large extent within a range where the paste viscosity does not become too high.

As the solvent, it is preferable to use a mixture of an organic solvent having a hydroxyl group (OH group). Specific examples of the organic solvent include terpineol (C ₁₀ H ₁₈ O), butyl carbitol acetate, pentanediol (2 2,4-trimethylpentanediol monoisobutyrate), dipentene (also known as Limonen), butyl carbitol and the like. A mixed solvent obtained by mixing these organic solvents is preferable because it is excellent in solubility for dissolving the above binder and the dispersibility of the phosphor paste is improved.

  In order to improve the dispersion stability of the phosphor particles in the phosphor paste, it is preferable to add a surfactant as a dispersant. The content of the surfactant in the phosphor paste is preferably 0.05% by mass to 0.3% by mass from the viewpoint of effectively obtaining the effect of improving the dispersion stability or the effect of neutralization described later. As specific examples of the surfactant, (a) anionic surfactant, (b) cationic surfactant, and (c) nonionic surfactant can be used. There is something.

  (A) Examples of the anionic surfactant include fatty acid salts, alkyl sulfates, ester salts, alkylbenzene sulfonates, alkyl sulfosuccinates, and naphthalene sulfonate polycarboxylic acid polymers.

  Examples of (b) cationic surfactants include alkylamine salts, quaternary ammonium salts, alkylbetaines, and amine oxides.

  (C) Nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene derivatives, sorbitan fatty acid esters, glycerin fatty acid esters, polyoxyethylene alkylamines, and the like.

  Furthermore, it is preferable to add a charge eliminating substance to the phosphor paste. The above-mentioned surfactants generally have a charge eliminating action for preventing the phosphor paste from being charged, and many of them correspond to charge eliminating substances. However, since the charge eliminating action varies depending on the type of phosphor, binder and solvent, it is preferable to test various types of surfactants and select the ones with good results. Examples of the charge removal material include fine particles made of a conductive material in addition to the surfactant. The conductive fine particles include carbon fine powder including carbon black, fine graphite powder, fine metal powder such as Al, Fe, Mg, Si, Cu, Sn, Ag, and fine powder composed of these metal oxides. Is mentioned. The amount of such conductive fine particles added is preferably in the range of 0.05 to 1.0 mass% with respect to the phosphor paste. By adding a charge-removing substance to the phosphor paste, the phosphor paste is charged, for example, the rise of the phosphor layer at the break of the address electrode in the center of the panel, the amount of phosphor paste applied to the cell and the groove Thus, it is possible to prevent a phosphor layer from being poorly formed, such as a slight variation in the state of adhesion, and to form a uniform phosphor layer for each cell.

  In addition, when a surfactant or carbon fine powder is used as a charge eliminating material as described above, the charge eliminating material is also evaporated or burned off in the phosphor firing step for removing the solvent and binder contained in the phosphor paste. Therefore, the neutralizing substance does not remain in the phosphor layer after firing. Therefore, there is no possibility that the driving (light emitting operation) of the PDP will be hindered by the fact that the neutralizing substance remains in the phosphor layer.

  When dispersing the europium-activated yttrium borate phosphor into the above-mentioned various mixtures, for example, a medium medium such as a high-speed stirring impeller disperser, colloid mill, roller mill, ball mill, vibration ball mill, attritor mill, planetary ball mill, sand mill, etc. Using a dry type disperser such as a cutter mill, a hammer mill, a jet mill, an ultrasonic disperser, a high-pressure homogenizer, etc. Can do.

  When the phosphor paste prepared as described above is applied or filled into the discharge cell 31, it can be performed by various methods such as a screen printing method, a photoresist film method, and an ink jet method. In particular, in the inkjet method, even when the pitch of the barrier ribs 30 is narrow and the discharge cells 31 are finely formed, the phosphor paste can be applied or filled between the barrier ribs 30 easily and accurately at a low cost. Therefore, it is preferable.

  Such a display such as the PDP 1 according to the present invention uses the red phosphor according to the present invention, whereby the luminance is improved and a moving image can be smoothly displayed.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

Example 1
(1) Preparation of red light emitting phosphor 1-1 [(Y, Gd) BO ₃ : Eu ³⁺ ] A red phosphor precursor was formed by a reaction crystallization method. Yttrium nitrate hexahydrate (Kanto Chemical Co., Ltd., purity 99.0%) 156.1 g, Gadolinium nitrate (Kanto Chemical Co., Ltd., purity 98.0%) 315.4 g, Europium nitrate hexahydrate After adjusting 26.0 g (manufactured by Kanto Chemical Co., Ltd., purity 98.0%) and 72.0 g of boric acid (manufactured by Kanto Chemical Co., Ltd., purity 99.5%) in pure water to 1,500 ml. The liquid temperature was kept at 60 ° C., stirring was performed using a stirring blade, and 500 ml of ammonia water (28%) kept at 60 ° C. in that state was added as a rush. After the addition, aging was performed for 10 minutes to obtain a red light emitting precursor. Thereafter, the red light emitting precursor was filtered and dried (105 ° C., 16 hours) to obtain a dry red light emitting phosphor precursor. Further, the dried red light emitting phosphor precursor was calcined at 1,200 ° C. for 2 hours, and then calcined at about 800 ° C. in an inert atmosphere for 4 hours. Thereafter, it was washed with 0.1 mol / L hydrochloric acid for 10 minutes and dried at 300 ° C. for 12 hours to obtain a red light emitting phosphor 1-1.

(2) Production of red light emitting phosphor 1-2 On the liquid surface of an aqueous solution in which 500 ml of ammonia water is dissolved at a rate of 60 ml / min, yttrium nitrate hexahydrate, gadolinium nitrate, europium nitrate hexahydrate and boric acid are dissolved. A red light-emitting phosphor 1-2 was obtained in the same manner as the red light-emitting phosphor 1-1 of (1) above, except that the red light-emitting precursor was precipitated at a constant rate.
(3) Preparation of red light emitting phosphor 1-3 Yttrium nitrate hexahydrate 156.1 g, gadolinium nitrate 315.4 g and europium nitrate hexahydrate 26.0 g were dissolved in pure water to 1,500 ml. It adjusted and it was set as the A liquid.
72.0 g of boric acid was dissolved in pure water and adjusted to 1,500 ml to obtain a solution B.
Next, the reaction vessel was filled with 1,500 ml of pure water at 60 ° C., and stirred using a stirring blade. In this state, the solution A and the solution B, which were also kept at 60 ° C., were transferred to the reaction vessel at a rate of 120 ml / min. Was added to the surface of the pure water at a constant rate. At this time, ammonia water was simultaneously added while controlling the pH to be 9. After the addition, aging was performed for 10 minutes to obtain a red light emitting precursor. Thereafter, the red light emitting precursor was filtered and dried (105 ° C., 16 hours) to obtain a dry red light emitting phosphor precursor. Further, the dried red light emitting phosphor precursor was calcined at 1,200 ° C. for 2 hours, and then calcined at about 800 ° C. in an inert atmosphere for 4 hours. Thereafter, it was washed with 0.1N hydrochloric acid for 10 minutes and dried at 300 ° C. for 12 hours to obtain a red light emitting phosphor 1-3.

(4) Preparation of red light-emitting phosphor 1-4 Similar to red light-emitting phosphor 1-3 in (3) above, except that liquid A, liquid B, and aqueous ammonia are added to pure water in the reaction vessel. A red light emitting phosphor 1-4 was obtained.

[Evaluation]
The phosphors 1-1 to 1-4 obtained in the above (1) to (4) were evaluated for composition analysis, emission intensity, and 1/10 afterglow time.

1. Composition analysis About the average content rate of the europium element on the surface of a fluorescent substance particle, X-ray photoelectron spectroscopy analyzer ESCALab200R by VG Elemental company was used.

  At this time, the phosphor sample was thoroughly agitated and then randomly divided into 50, and the content of europium element was measured twice for each divided sample. The average content and standard deviation (σ) of the europium element on the particle surface were determined by relative values with phosphor 1-1 as 100.

2. Luminance Luminance was irradiated with vacuum ultraviolet rays using an excimer 146 nm lamp (manufactured by Ushio Inc.) in a vacuum chamber of 0.1 to 1.5 Pa to emit red light from the phosphor. Next, the emission luminance of the obtained red light was measured using a detector (MCPD-3000 manufactured by Otsuka Electronics Co., Ltd.). And the peak intensity of light emission was calculated | required by the relative value which made the red light emission fluorescent substance 1-1 100.

3. 1/10 Afterglow Time Measured using a fluorescence lifetime measuring instrument. The afterglow time is the time until the emission intensity after blocking the excitation light becomes 1/10 of the emission intensity immediately before blocking, and the relative value with the red light emitting phosphor 1-1 as 100 is 1/10 afterglow. Seeking time.

  The results are shown in Table 1.

  As can be seen from Table 1, the emission luminance was 103 to 107 when the red emission phosphor 1-1 (Comparative Example 1) was 100, and the red emission phosphors 1-2 to 1-4 of the present invention were 103 to 107. . Regarding the 1/10 afterglow time, when the red light emitting phosphor 1-1 (Comparative Example 1) is 100, the red light emitting phosphors 1-2 to 1-4 of the present invention are 92 to 79, which is a significant improvement. Was recognized.

Example 2
(1) Production of red-emitting phosphor 2-1 18.73 g of yttrium nitrate hexahydrate, 37.84 g of gadolinium nitrate, and 3.12 g of europium nitrate hexahydrate were dissolved in pure water to 1,500 ml. It adjusted and it was set as the A liquid.
Boric acid 8.64g was melt | dissolved in the pure water, and it adjusted to 1,500ml, and was set as B liquid.

  Next, the reaction vessel is filled with 5,000 ml of the red light emitting precursor dispersion prepared in advance in (4) of Example 1 above, and the mixture is kept at 60 ° C. and stirred using a stirring blade. Similarly, liquid A and liquid B maintained at 60 ° C. were added at a rate of 55 ml / min into the dispersion in the reaction vessel at a constant rate in the liquid. At this time, ammonia water was simultaneously added to the liquid while controlling to pH = 9. After the addition, aging was performed for 10 minutes to obtain a red light emitting precursor. Thereafter, the red light emitting precursor was filtered and dried (105 ° C., 16 hours) to obtain a dry red light emitting phosphor precursor. Further, the dried red light emitting phosphor precursor was baked under 1,300 ° C. oxidation conditions for 2.5 hours, and then baked in an inert atmosphere at around 900 ° C. for 6 hours. Thereafter, it was washed with 0.1N hydrochloric acid for 10 minutes and dried at 300 ° C. for 12 hours to obtain a red light emitting phosphor 2-1.

(2) Production of red-emitting phosphor 2-2 Red-emitting phosphor 2-2 in the same manner as phosphor 2-1 in (1) above, except that the raw material mass of liquid A and liquid B is increased 1.67 times. Got.

(3) Production of red light-emitting phosphor 2-3 Red light-emitting phosphor 2-3 in the same manner as phosphor 2-1 in (1) except that the raw material masses of liquid A and liquid B are increased by 2.25 times. Got.

[Evaluation]
About the red light-emitting phosphor 1-4 produced in Example 1 and the red light-emitting phosphors 2-1 to 2-3 obtained in the above (1) to (3), composition analysis, emission intensity, 1/10 remaining Evaluation was performed for light time.

1. Composition analysis About the average content rate of the europium element on the surface of a fluorescent substance particle, X-ray photoelectron spectroscopy analyzer ESCALab200R by VG Elemental company was used.

  At this time, the phosphor sample was agitated well and then randomly divided into 50, and the average value obtained by measuring the europium element content twice for each divided sample was determined as the average europium element content on the particle surface.

  Regarding the average content of the europium element in the phosphor particles, after dissolution with hydrofluoric acid, an inductively coupled plasma emission spectrometer SPS5000 manufactured by Seiko Denshi Kogyo or an inductively coupled plasma mass spectrometer QP-Ω manufactured by VG Elemental was used. At the time of quantification, a standard stock solution separately prepared by Kanto Chemical and nitric acid (ultra high purity manufactured by Kanto Chemical) were prepared, and quantified by a calibration curve method. The red light emitting phosphors 1-4 and 2-1 to 2-3 are relative values with the average content of the europium element on the particle surfaces of the red light emitting phosphors 1-4 and 2-1 to 2-3 as 100. The average content of europium element inside the particles was determined.

2. Red light was emitted from the phosphor by irradiating with vacuum ultraviolet rays using an excimer 146 nm lamp (manufactured by Ushio Inc.) in a vacuum chamber having an emission luminance of 0.1 to 1.5 Pa. Next, the emission luminance of the obtained red light was measured using a detector (MCPD-3000 manufactured by Otsuka Electronics Co., Ltd.). And the peak intensity of light emission was calculated | required by the relative value which made the red light emission fluorescent substance 1-1 100.

3. 1/10 Afterglow Time Measured using a fluorescence lifetime measuring instrument. The afterglow time is the time until the emission intensity after blocking the excitation light becomes 1/10 of the emission intensity immediately before blocking, and the relative value with the red light emitting phosphor 1-1 as 100 is 1/10 afterglow. Seeking time.

  The results are shown in Table 2.

  As is clear from Table 2, the emission luminance was 112 to 119 when the red emission phosphor 1-1 (Comparative Example 1) was 100, and the red emission phosphors 2-1 to 2-3 of the present invention were 112 to 119. . Regarding the 1/10 afterglow time, when the red light emitting phosphor 1-1 (Comparative Example 1) is 100, the red light emitting phosphors 2-1 to 2-3 of the present invention are 78 to 77, which is a significant improvement. Was recognized.

Example 3
(1) Preparation of green phosphor (Zn ₂ SiO ₄ : Mn ²⁺ ) Colloidal silica containing 45 g of silicon dioxide (PL-3 manufactured by Fuso Chemical Industry Co., Ltd.) and 219 g of ammonia water (28%) were mixed with pure water. The liquid A was adjusted to 1500 ml. Simultaneously, 424 g of zinc nitrate hexahydrate (manufactured by Kanto Chemical Co., Inc., purity 99.0%) and 21.5 g of europium nitrate hexahydrate (manufactured by Kanto Chemical Co., Ltd., purity 98.0%) are dissolved in pure water. The liquid B was adjusted to 1500 ml.

  After keeping A liquid and B liquid at 40 degreeC, it supplied to the Y-shaped reaction apparatus with the addition rate of 1200 ml / min using the roller pump. The precipitate obtained by the reaction was diluted with pure water, and then subjected to pressure filtration for solid-liquid separation. Subsequently, drying was performed at 100 ° C. for 12 hours to obtain a dried precursor.

  Next, the obtained precursor was baked at 1200 ° C. for 7 hours in an atmosphere of 100% nitrogen to obtain a green light emitting phosphor.

(2) Production of blue-emitting phosphor (BaMgAl ₁₀ O ₁₇ : Eu ²⁺ ) Pure water 3 was prepared by using 58.0 g of barium nitrate, 8.9 g of europium nitrate hexahydrate, and 51.3 g of magnesium nitrate hexahydrate. A solution was prepared by dissolving in 1,000 ml. Further, 850.3 g of aluminum nitrate nonahydrate was dissolved in 3,000 ml of pure water to obtain a liquid B.
After keeping A liquid and B liquid at 70 degreeC, it supplied to the Y-shaped reaction apparatus with the addition rate of 1400 ml / min using the roller pump. The precipitate obtained by the reaction was diluted with pure water, and then subjected to pressure filtration for solid-liquid separation. Subsequently, drying was performed at 100 ° C. for 12 hours to obtain a dried precursor.

  Next, the obtained precursor was baked at 1700 ° C. for 6 hours in an atmosphere of 100% nitrogen to obtain a blue light emitting phosphor.

2. Preparation of phosphor paste Using the red light emitting phosphors 1-1 and 2-3 produced in Example 1 and the green light emitting phosphor and blue light emitting phosphor produced above, phosphor pastes were prepared respectively. At the time of preparation, each phosphor was mixed with a 1: 1 mixture of ethyl cellulose, polyoxylene alkyl ether, terpineol and pentadiol so that the solid content concentration of each phosphor would be 50% by mass. Each obtained mixture was made into the red light emission fluorescent substance paste 3-1 and 3-2 apply | coated in the cell of PDP mentioned later, the green light emission fluorescent substance paste, and the blue light emission fluorescent substance paste.

3. Manufacture of PDP (1) Manufacture of PDP 3-1 Using the red light emitting phosphor paste 3-1 prepared above, the green light emitting phosphor paste, and the blue light emitting phosphor paste, the PDP shown in FIG. Manufactured.

  First, on the glass substrate used as the front plate 10, a transparent electrode is arrange | positioned as the transparent electrode 11a. Next, the bus electrode 11b is formed on the transparent electrode 11a by sputtering Cr—Cu—Cr and performing photoetching, and the display electrode 11 is formed. Then, a low-melting glass is printed on the surface glass substrate 10 so as to cover the display electrodes 11, and is baked at 500 to 600 ° C., thereby forming the dielectric layer 12. Further, a protective film 13 is formed on the dielectric layer 12 by electron beam evaporation of MgO.

  On the other hand, the address electrode 21 is formed on the back plate 20 by printing an Ag thick film and baking it. Then, partition walls 30 are formed on the back plate 20 and on both sides of the address electrodes 21. The partition walls 30 can be formed by printing low-melting glass with a pitch of 0.2 mm and baking. Further, the red light emitting phosphor paste 2-1, the green light emitting phosphor paste, and the blue light emitting phosphor paste are applied to the bottom surface (on the address electrode 21) 31a and the side surface 30a of the discharge cell 31 partitioned by the barrier ribs 30. Apply or fill. At this time, one color phosphor paste is used for each discharge cell 31. Thereafter, the phosphor paste is dried or baked to remove organic components in the paste, and phosphor layers 35R, 35G, and 35B having different emission colors are formed in the discharge cells 31R, 31G, and 31B, respectively.

  Then, the front plate 10 and the back plate 20 on which the electrodes 11, 21, etc. are arranged are aligned so that the electrode arrangement surfaces face each other, and the periphery is sealed while maintaining a gap of about 1 mm. Sealed with glass (not shown). A gas mixture of xenon (Xe) that generates ultraviolet rays by discharge and neon (Ne) as a main discharge gas is sealed between the substrates 10 and 20 and hermetically sealed. It was.

(2) Production of PDP 3-2 In the above (1), except that the red light emitting phosphor paste 3-2 prepared above is used instead of the red light emitting phosphor paste 3-1, the PDP3- In the same manner as in Example 1, PDP 3-2 was produced.

[Evaluation]
About PDP3-1 and 3-2 manufactured above, the white brightness | luminance when an equivalent sustain voltage (180V alternating voltage) was applied to the electrode was measured. And the relative value of PDP3-2 when the white luminance of PDP3-1 was set to 100 was calculated | required. In addition, subjective evaluation was performed on the image quality when moving images were displayed.

  The results are shown in Table 3.

  As is clear from Table 3, when the PDP 3-1 (Comparative Example 1) is 100, the white luminance in the PDP is 107 for the PDP 3-2 of the present invention. In addition, as for the image quality when displaying a moving image, the PDP 3-1 (Comparative Example 1) showed a noticeable tail, but the PDP 3-2 of the present invention did not recognize the tail.

  According to the phosphor of the present invention, in the europium-activated yttrium borate phosphor, the standard deviation (σ) of the average content of -ropium on the surface of each phosphor particle is 0 ≦ σ ≦ 10, In addition, by increasing the average content of the particle surface, the emission intensity can be improved and the afterglow time can be shortened.

  Further, the same effect can be obtained in a plasma panel display (image display such as a computer, a television, and X-ray photography) using the phosphor of the present invention.

It is the schematic block diagram which showed an example of the plasma panel display which concerns on this invention.

Explanation of symbols

1 PDP
10, 20 Substrate 30 Bulkhead 31 Discharge cell 35G Phosphor layer

Claims (4)

A europium-activated yttrium borate-based phosphor, wherein the standard deviation (σ) of the average europium content on the surface of each particle is 0 ≦ σ ≦ 10. The europium-activated yttrium borate phosphor according to claim 1, wherein the average europium content on the particle surface is higher than that in the particle. The europium-activated yttrium borate phosphor according to claim 1, wherein the average europium content in the particles is 50 mol% or more and 99 mol% or less of the average europium content on the particle surface. A plasma display panel comprising the europium-activated yttrium borate phosphor according to claim 1.

Images