KR20030095042A - Compositions of oxy-halides red phosphor and their preparing method - Google Patents

Abstract

PURPOSE: A halogenide-based red fluorescent substance and its preparation method are provided, to improve the emission luminance by a low voltage electron ray, the stability in high vacuum and the color purity. CONSTITUTION: The halogenide-based red fluorescent substance is represented by Ln1-aOX:Eua, wherein Ln is La, Y or Gd; X is Br, Cl or F; and 0.005<=a<1.0. The method comprises the steps of adding urea to a lanthanide (Ln) aqueous solution to hydrolyze it and filtering and drying it; and adding a halogenide (X)-containing solution and a europium (Eu)-containing solution to the dried one drop by drop, drying it and sintering the obtained powder at a temperature of 800-1,200 deg.C under the nitrogen atmosphere. Preferably the concentration of the lanthanide (Ln) aqueous solution is 0.05-1.5 mol/L.

Description

Compositions of oxy-halides red phosphor and their preparing method

The present invention relates to a composition and a method for preparing a halogenated red phosphor, and more particularly, in the preparation of a red phosphor, Ln _1-a OX as a matrix and europium (Eu) as an activator is added to the red phosphor. Unlike the solid state reaction method, which has been heat-treated at a high temperature, it is manufactured by hydrolysis at a relatively low temperature, so that the luminance of light emitted by low-voltage electron beams is excellent, stable physical properties in high vacuum, and color purity are excellent. The present invention relates to a more suitable composition and method of manufacturing a halogenide-based red phosphor when applied to a field emission display driven by.

Field emission displays (FEDs) are a new generation of flat panel displays that can supplement and replace the shortcomings of cathode ray tubes (CRTs), which are most often used as information displays, and are a new type of display using vacuum flat cathode tube. Based on low voltage cathode excitation below 1 kW.

That is, in order to drive an FED having an anode driving voltage of about 1 kV or less, a phosphor for a low speed electron beam is required as the phosphor for the FED.

However, typical ZnO: Zn phosphors among the FED phosphors used for the above-mentioned purposes have a very wide light emitting area, which is not suitable for application as a color display.

In addition, emulsion phosphors such as ZnS: Ag, Cl, and CdS: Ag, Cl, etc., which are commonly used red phosphors, contain sulfur compounds, and when used, electrons emitted from the cathode may accelerate and collide with the sulfide phosphor layer. It is known to adversely affect the excitation source of the device due to the decomposition of the surface of the phosphor layer and the decomposition of the phosphor itself, in addition to the action of emitting the phosphor layer.

Currently widely known red phosphors include Y ₂ O ₃ : Eu-based phosphors, but the phosphors are mixed with a large amount of In ₂ O ₃ as a conductive material in order to increase the insulation, and the phosphors flowing through the used In ₂ O ₃ are ineffective. Since the current increases, the luminous efficiency in the low voltage driving region is lowered, and the reliability is also lowered.

Conventional methods for preparing phosphors are prepared in powder form by a solid phase reaction method in which solid materials such as lanthanum oxide, yttrium oxide, gadolinium oxide, and ammonium bromide, ammonium chloride, and ammonium fluoride are mixed and heat treated. A high temperature of 1200 ° C. or higher is applied in the heat treatment process. However, the halogenide-based material is melted at such a high temperature, resulting in aggregation of phosphor particles or inaccurate chemical stoichiometry, resulting in lowering of luminance.

In addition, there is an urgent need for a new method for the production of phosphor powders having properties that can satisfy the characteristics such as particle size, particle shape and uniform distribution of active agent in the matrix, and in response to such research, Externally, research on oxide-based phosphors as well as emulsion-based phosphors has been actively conducted.

In order to solve the above problems, the inventors of the present invention prepare a halogenated red phosphor, but use europium (Eu) as an activator, and use the hydrolysis method in preparing the red phosphor. When the applied liquid phase method was applied in the temperature range of 800 ~ 1200 ℃ it was found that compared to the conventional solid-phase reaction method can be produced a halogenide-based phosphor at a relatively low temperature to complete the present invention.

Accordingly, an object of the present invention is to provide a halogenide-based red phosphor added with europium (Eu) and a method of manufacturing the same, which are excited by a low-voltage electron beam and exhibit a more desirable effect when applied to a field emission display. .

1 is a graph showing the diffraction intensity and the diffraction angle of La _0.95 OBr: Eu _0.05, La _0.95 OCl: Eu _0.05 and La _0.95 OF: Eu _{0.05 in} the halogenide-based red phosphor prepared according to the embodiment of the present invention.

2 is a graph showing excitation spectra of La _0.95 OBr: Eu _0.05, La _0.95 OCl: Eu _0.05, and La _0.95 OF: Eu _{0.05 in} the halogenide-based red phosphor prepared according to the embodiment of the present invention.

3 is a graph showing emission spectra of La _0.95 OBr: Eu _0.05, La _0.95 OCl: Eu _0.05, and La _0.95 OF: Eu _{0.05 in} the halogenide-based red phosphor prepared according to the embodiment of the present invention.

The present invention is characterized by a halogenated red phosphor represented by the following formula (Ln _1-a OX) and adding europium (Eu) as an activator.

Ln _1-a OX: Eu _a

Where Ln is La, Y or Gd, X is Br, Cl or F and a is in the range 0.005 ≦ a <1.0.

In another aspect, the present invention comprises the steps of adding a urea to the lanthanide (Ln) aqueous solution to hydrolyze and then dried by filtration to prepare a dried body; Preparation of a halogenide-based red phosphor comprising the step of adding a solution containing a halogenide (X) and a solution containing europium (Eu) dropwise to the dried body and then drying the powder obtained by drying at 800 to 1200 ℃ and nitrogen atmosphere It includes a method.

Hereinafter, the present invention will be described in more detail based on the production method.

In order to prepare a halogenated red phosphor according to the present invention, first, a lanthanide (Ln) -containing compound is used, and as lanthanide, lanthanum (La), yttrium (Y), and gadolinium (Gd) may be used. Lanthanum (La) sources include lanthanum oxide (La ₂ O ₃ ), lanthanum hydroxide (La ₂ (OH) ₃ ), and lanthanum nitrate (La (NO ₃ ) ₃ · 6H ₂ O) and yttrium (Y). Yttrium oxide (Y ₂ O ₃ ) and yttrium nitrate (Y (NO ₃ ) ₃ · 6H ₂ O) as a source, gadolinium oxide (Gd ₂ O ₃ ) and gadolinium nitride (Gd (NO ₃ ) as a source of gadolinium (Gd) ) ₃ · 6H ₂ O) for the manufacture of a lanthanide aqueous solution by using nitric acid and water, the concentration is based on the composition of the above-mentioned formula (I), the concentration of the lanthanum, yttrium, gadolinium, such as a lanthanide component 0.05 ~ 1.5 ㏖ / L, but preferably in a high yield by adjusting the concentration of 0.1 ~ 0.75 mol / L Can get a body. In this case, when the concentration of the metal component is less than 0.05 mol / l, the amount of solvent (water) is used and the time for the collection of the precipitate is not economical, and when it exceeds 1.5 mol / l, the precipitate becomes a slurry after the reaction. There is a problem.

The amount of urea used to facilitate the hydrolysis of the lanthanide component is added in a molar ratio of 1: 10 to all the lanthanide components used, filtered after hydrolysis, and dried at 80 to 150 ° C. to prepare a dry body. At this time, if the amount of added urea is less than 10 times the molar ratio of the lanthanide component, the amount is insufficient as a precipitant. If the amount exceeds 50 times, the precipitant is excessively used, so it is not economical.

As the halogenide (X) compound, ammonium bromide (NH ₄ Br) is used as the bromine (Br) source, ammonium chloride (NH ₄ Cl) is used as the chlorine (Cl) source, and ammonium fluoride is used as the fluorine (F) source. In consideration of melting and volatilization in the final heat treatment process, the lanthanide component may be used in an amount of 1: 1 to 1.5 molar ratio, but preferably 1: 1.1 to 1.5 molar ratio.

As the active agent, europium (Eu) is added as a europium-containing compound, and specifically, for the europium-containing compound, for example, europium oxide (Eu ₂ O ₃ ), europium nitrate (Eu (NO ₃ ) ₃ 6H ₂ O), europium halogenide (EuBr ₃ , EuCl ₃ , EuF ₃ ) can be used, according to the halogenide compound to be synthesized, the compound used as europium source is europium oxide (Eu ₂ O ₃ ) is used by dissolving in nitric acid or europium nitrate (Eu (NO ₃ ) ₃ · 6H ₂ O), europium halogenide (EuBr ₃ , EuCl ₃ , EuF ₃ ) in water. The solution is slowly dropped into the dry dry body and dried at 80 to 150 ° C. for about 48 hours. The dried powder is calcined at about 800 to 1400 ° C. in a reducing atmosphere using 5 to 25% hydrogen gas to produce a halogenated blue phosphor. If the firing temperature is less than 800 ° C., the desired phosphor is not formed. Fluorescent properties do not appear, and if it exceeds 1400 ° C, the halogenide decomposes and the composition of the desired phosphor is not achieved.

The new manufacturing method according to the present invention as described above, unlike the conventional manufacturing method, the red phosphor is produced at a relatively low temperature, and the loss of halogenide ions can be adjusted to match the chemical quantitatively well, Since it is possible to minimize the incorporation of impurities without the grinding process, such as ball milling to control the particle size, there is a feature that can produce a small amount of phosphor and fine powder phosphor.

In addition, the halogenide-based red phosphor according to the present invention has excellent luminescence brightness in low-speed electron beams, has stable physical properties even in high vacuum, and is suitable for application to field emission displays (FEDs) driven by low-voltage electron beam excitation with excellent color purity. Do.

In other words, halogenide-based phosphors with europium (Eu) added as red phosphors for FED have not been studied in Korea or abroad, and also have high efficiency due to low-voltage cathode ray emission and are stable in high vacuum to sulfide-based and oxide-based phosphors. In addition to the system phosphors, it is worth researching as a phosphor for FED, and it is expected to have a great potential for application in the future.

Although this invention is demonstrated in detail based on an Example, this invention is not limited to a following example.

Example: La _0.95 OF: Eu _0.05 Preparation of Phosphor

A phosphor represented by Chemical Formula 1 was prepared, but 11.7 g of lanthanum nitrate was dissolved in water as a lanthanum to prepare an aqueous solution, followed by hydrolysis by addition of 91.7 g of urea, followed by drying at 80 ° C. after filtration. In addition, as a europium source, 1.4 g of europium nitrate and 2.9 g of ammonium fluoride were dissolved in water to make a solution, which was slowly dropped into the dried product and dried at 150 ° C. for 24 hours. The dried powder was calcined at 1100 ° C. in a nitrogen atmosphere to prepare La _0.95 OF: Eu _0.05 in the halogenide-based red phosphor according to the present invention.

In the above example, lanthanum nitrate, a lanthanum-containing compound of lanthanide, was used ammonium fluoride, a fluorine-containing compound, and europium nitrate was used as europium source. It can be performed by replacing with a compound containing and a compound containing a halogenide. In addition, in the following experimental example, the red phosphor prepared according to the method of the above example was applied to the compound containing lanthanum as lanthanide, and the red phosphor with bromine, chlorine and fluorine as the halogenide was used, and the intensity of excitation and the excitation spectrum were used. And although the emission spectrum was measured, the following results can be obtained also as a red phosphor according to the composition of Formula 1 of the present invention.

Experimental Example 1 La according to X _0.95 OX: Eu _0.05 Diffraction Intensity Measurement of Red Phosphor

The diffraction intensity according to the diffraction angles of La _0.95 OBr: Eu _0.05, La _0.95 OCl: Eu _0.05, and La _0.95 OF: Eu _{0.05 in} the halogenide-based red phosphor of the present invention prepared according to the above embodiment was measured and the result was measured. 1, it can be seen that the tetragonal structure of PbFCl is shown.

Experimental Example 2 La according to X _0.95 OX: Eu _0.05 Excitation Spectrum Measurement of Red Phosphor

Excitation spectra of La _0.95 OBr: Eu _0.05, La _0.95 OCl: Eu _0.05, and La _0.95 OF: Eu _0.05 were measured in the halogenide-based red phosphor of the present invention prepared according to the above embodiment. Shown in

As shown in FIG. 2, it can be seen that the charge transfer band is changed according to the X ion.

Experimental Example 3 La according to X _0.95 OX: Eu _0.05 Measurement of emission spectrum of red phosphor

The light emission spectra of La _0.95 OBr: Eu _0.05, La _0.95 OCl: Eu _0.05, and La _0.95 OF: Eu _0.05 were measured in the halogenide-based red phosphor of the present invention prepared according to the above example, and the results are shown in FIG. 3. Indicated.

As shown in Fig. 3, it can be seen that the main peak changes with the change of X.

As described above, the halogenated red phosphor added with europium as an active agent prepared according to the present invention can be easily synthesized at 800 to 1200 ° C., which is relatively low temperature compared to the conventional solid phase reaction by using hydrolysis. In the low-voltage low-speed electron beam, the light emission luminance is excellent, a stable phase is maintained in a vacuum state, and different matrixes can be synthesized according to the change of lanthanide (Ln) and halogenide (X). According to the prepared mother, red light having a main peak of 610 nm to 619 nm when the activator europium is emitted, and the main peak can be changed according to the concentration of the europium can produce a red phosphor having excellent color purity.

In addition, since halogenide-based phosphors to which europium (Eu) is added as a red phosphor for FED have not been studied not only in Korea but also abroad, according to the present invention, a halogenated red phosphor suitable for FED can be prepared. In addition, it is expected that the research potential as a new phosphor and its application to the industry will be very large in the future research of the phosphor for FED together with the emulsion phosphor and the oxide phosphor.

Claims (5)

Halogenide _- based red phosphor represented by Chemical Formula 1 by adding Ln _1-a OX as a parent and adding europium (Eu) as an activator: [Formula 1] Ln _1-a OX: Eu _a Where Ln is La, Y or Gd, X is Br, Cl or F and a is in the range 0.005 ≦ a <1.0. Preparing a dried body by hydrolyzing and adding urea to an lanthanide (Ln) aqueous solution, followed by filtration and drying; Calcining the powder obtained by dropwise addition of a solution containing halogenide (X) and a solution containing europium (Eu) to the dried body at 800 to 1200 ° C. and a nitrogen atmosphere. Method for producing a halogenide-based red phosphor represented by the following formula (1) comprising a. [Formula 1] Ln _1-a OX: Eu _a Where Ln is La, Y or Gd, X is Br, Cl or F and a is in the range 0.005 ≦ a <1.0. The method of claim 2, wherein the urea is in a molar ratio of from 1:10 to 50 with respect to the lanthanide component. The method of claim 2, wherein the concentration of the lanthanide-containing aqueous solution is 0.05 to 1.5 mol / l. The method of claim 2, wherein the concentration of the halogenide component is from 1: 1 to 1.5 molar ratio with respect to the lanthanide component.