KR20030090983A - Red-emitting phosphor for vacuum ultraviolet and a preparation method thereof - Google Patents

Abstract

PURPOSE: A red fluorescent substance for VUV(Vacuum UltraViolet), its preparation method and a plasma display panel or light emitting lamp containing the fluorescent substance are provided, to obtain a fluorescent substance having a high absorption peak at a range of VUV and an excellent emission luminance. CONSTITUTION: The red fluorescent substance is represented by (Y1-a-b-cGdaEubMc)2O3, wherein M is a rare earth metal selected from the group consisting of Dy, Sm, Nd, Tm, Pr and Sc; and 0<=a<1, 0.005<=b<=0.2, and 0.00001<=c<=0.1. The method comprises the steps of dissolving a yttrium compound, a gadolinium compound, a metal compound of a rare earth metal selected from the group consisting of Dy, Sm, Nd, Tm, Pr and Sc, citric acid and ethylene glycol in a solvent to prepare a precursor solution; drying and heating the precursor solution at 300-1,500 deg.C with spraying the solution by an aerosol generator to prepare a fluorescent substance powder; and heating the fluorescent substance powder at 800-1,500 deg.C for 1-5 hours.

Description

RED-EMITTING PHOSPHOR FOR VACUUM ULTRAVIOLET AND A PREPARATION METHOD THEREOF}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a red phosphor for a plasma display panel (PDP) and a method of manufacturing the same, and more specifically, to a (YGd) ₂ O ₃ : Eu phosphor, which is prepared by adding a rare earth element as an activator in a vacuum ultraviolet ray. The red fluorescent substance for plasma display panels excellent in the luminescent characteristic of this invention, and its manufacturing method is provided.

(YGd) ₂ O ₃ : Eu phosphor is used as a fluorescent material for lamps, and (YGd) BO ₃ : Eu is often used as a red phosphor for vacuum ultraviolet rays, but (YGd) BO ₃ : Eu phosphor has high luminance under vacuum ultraviolet rays. On the other hand, there are problems with color coordinates and afterglow time, and Korean Patent Application No. 2001-17535 uses a phosphor mixed with (YGd) ₂ O ₃ : Eu and (YGd) BO ₃ : Eu for plasma display. In addition, since the (YGd) ₂ O ₃ : Eu phosphor has good light emission intensity under ultraviolet rays of 254 nm or more, but low light emission luminance under vacuum ultraviolet rays, it is necessary to increase the light emission luminance under vacuum ultraviolet rays.

On the other hand, spray pyrolysis has been actively studied as a method for producing phosphor powder because spherical powder can be produced. However, in order for the phosphor powders to exhibit excellent luminescence properties, the specific surface area and the surface defects should be small. Since the phosphor powders prepared by the conventional spray pyrolysis method have a hollow porous form during the drying and pyrolysis of droplets, These conditions are not met. In particular, in the pyrolysis process of mass production, the obtaining of the porous powder is a more serious problem.

In order to solve this problem, the present inventors have continuously studied to increase the emission luminance of (YGd) ₂ O ₃ : Eu phosphor in vacuum ultraviolet light, the second doping material in (YGd) ₂ O ₃ : Eu phosphor By adding a rare earth metal and adding citric acid and an ethylene glycol solution together in preparing a spray solution, it is possible to develop an yttrium gadolinium-based phosphor having a significantly improved luminescence property in vacuum ultraviolet rays.

Accordingly, an object of the present invention is to provide dysprosium (Dy), samarium (Sm), thulium (Tm), neodymium (Nd), praseodymium (Pr), or scandium (YGd) ₂ O ₃ : Eu phosphor as a second activator. By adding a rare earth metal such as Sc), it is to provide a red phosphor for vacuum ultraviolet rays with excellent luminescence properties.

Another object of the present invention is to provide a method for producing a red phosphor containing a polymer material therein by adding citric acid and ethylene glycol solution in the preparation of the spray in the method of producing a phosphor using spray pyrolysis.

1 is a schematic diagram of a conventional spray pyrolysis process apparatus,

FIG. 2 is an electron micrograph of (Y _0.38 Gd _0.57 Dy _0.0004 ) ₂ O ₃ : Eu _0.05 phosphor powder prepared by adding citric acid and ethylene glycol according to Example 1 of the present invention; FIG.

3 is an electron micrograph of (YGd) ₂ O ₃ : E phosphor powder prepared by adding citric acid and ethylene glycol according to Comparative Example 1 of the present invention;

4 is an electron micrograph of (YGd) ₂ O ₃ : E phosphor powder without citric acid and ethylene glycol added according to Comparative Example 2 of the present invention,

5 is an emission spectrum in the vacuum ultraviolet region of the yttrium gadolinium-based red phosphor prepared in Examples 1 and 2 of the present invention and the phosphor powders prepared in Comparative Examples 1 and 3, respectively;

6 is a light emission spectrum in a vacuum ultraviolet region of phosphors obtained by adding a polymer material according to Examples 3 and 4 of the present invention.

In order to achieve the above object, the present invention provides a yttrium gadolinium-based red phosphor for vacuum ultraviolet rays represented by the following formula (1) and a method of manufacturing the same:

Formula 1

(Y _1-abc Gd _a Eu _b M _c ) ₂ O ₃

In the above formula, M is a rare earth metal selected from Dy, Sm, Nd, Tm, Pr, and Sc, and 0 ≦ a <1, 0.005 ≦ b ≦ 0.2, 0.00001 ≦ c ≦ 0.1.

Hereinafter, the present invention will be described in detail.

The yttrium gadolinium-based red phosphor for vacuum ultraviolet rays represented by Chemical Formula 1 according to the present invention is an yttrium (Y) compound; Gadolinium (Gd) compounds; Europium (Eu) compounds; And a rare earth metal compound selected from dysprosium (Dy), samarium (Sm), neodymium (Nd), thulium (Tm), praseodymium (Pr), and scandium (Sc). After dissolving citric acid and ethylene glycol in a solvent, the resulting precursor mixture solution was sprayed into fine droplets using a droplet generating apparatus, followed by drying and heat treatment at a reactor temperature of 300 to 1500 ° C. to synthesize phosphor powder, and synthesized phosphor powder. It can be prepared by heat treatment at 800 to 1500 ℃ for 1 to 5 hours.

<Preparation of phosphor particle precursor solution>

In the production process of the precursor solution for producing the phosphor particles of the present invention, an yttrium compound, a gadolinium compound or a europium compound is used as a matrix of the phosphor powder, and Dy, Sm, Nd, Tm as an activator for doping the matrix. Rare earth metal compounds selected from Pr and Sc are used.

The precursor materials are used by dissolving in water, alcohol or weak acid, and are preferably in the form of nitrate, acetate, chloride, hydrate, oxide or carbonate so that they are easily dissolved, and the amount of the precursor material may be appropriately adjusted to satisfy the condition of Chemical Formula 1.

The present invention is characterized in that citric acid and ethylene glycol, which can cause an esterification reaction, are added to produce a polymer material in the resulting droplets, which are each dissolved in a solvent such as distilled water. It is used mixed with the mixed solution.

Yttrium compound, gadolinium compound, or europium compound as a phosphor matrix; Rare earth metal compounds selected from among Dy, Sm, Nd, Tm, Pr and Sc as active agents; And the total concentration of the precursor solution including citric acid and ethylene solution is preferably in the range of 0.02 to 2M, the size of the phosphor particles is determined according to this concentration. When the said concentration is less than 0.02 M, productivity of fluorescent substance powder falls, and when it is 2 M or more, it is difficult to spray. In addition, in order to increase the luminescence brightness of the resulting phosphors, conventional fluxes used in common phosphor synthesis processes can be added to the spray solution, for example, chlorides, carbonates or phosphates of alkali metals.

Conventional phosphor powders composed only of yttrium compound, gadolinium compound, europium compound and rare earth metal compound without addition of citric acid and ethylene glycol, and prepared by spray pyrolysis process, have a hollow porous form and thus have a continuous high temperature heat treatment process. The disadvantage is that the spherical shape is fragile. On the contrary, when the citric acid and the ethylene glycol solution is added to the precursor mixture solution according to the present invention, the obtained powders have a filled shape, so that the spherical shape can be maintained even after continuous high temperature heat treatment. The surface shape of the is better and can have an excellent light emission luminance.

At this time, the addition amount of citric acid and ethylene glycol and the mixing ratio of the activator metal (M) are very important for the shape control of the red phosphor powder and the luminescence brightness. In the present invention, optimal luminescence is maintained while maintaining the spherical shape even after a high temperature heat treatment process. Appropriate addition amounts and mixing ratios of citric acid, ethylene glycol and activator metal (M) exhibiting characteristics were determined. That is, the preferred concentrations of the citric acid and ethylene glycol solution added in the preparation of the spray solution is 0.01 to 5M, when each of these concentrations is lower than 0.01M it is difficult to form a solid spherical phosphor particles, which is higher than 5M In this case, the viscosity of the spray solution becomes high, making spraying difficult.

1 is a schematic view of a spray pyrolysis process apparatus. The spray pyrolysis processing apparatus includes an ultrasonic droplet generator 1, a tubular reactor 2 for drying and pyrolyzing droplets, a filter 3 for particle recovery, and the like. Droplets of several micron size produced by the ultrasonic droplet generator 1 are transported into the reactor 2 by a carrier gas, and spherical precursor powder is obtained by drying and pyrolysis.

<Spray of droplets>

The precursor solution obtained above is sprayed onto the droplets using a spray apparatus, and the diameter of the droplets preferably ranges from 0.1 to 100 µm. If the diameter of the droplet is less than 0.1 mu m, the size of the resulting phosphor particles is too small, and if larger than 100 mu m, the size of the phosphor particles is too large.

The spray apparatus may be an ultrasonic spray apparatus, an air nozzle spray apparatus, an ultrasonic nozzle spray apparatus, a filter expansion aerosol generator (FEAG), an electrostatic spray apparatus, or the like. The ultrasonic nebulizer and the FEAG can produce fine phosphor powder having a sub-micron size at a high concentration, and the air nozzle and the ultrasonic nozzle can produce a large amount of submicron-sized particles at the micron. In addition, to control the shape of the resulting phosphor powder, an ultrasonic droplet generator capable of generating fine droplets of several microns in size is more suitable.

<Production of Phosphor Powder>

Fine droplets generated from the droplet generator are converted into precursors of phosphor particles in a hot tubular reactor. At this time, the temperature of the reaction furnace is preferably 200 to 1500 ℃ range that can dry the precursor materials. The phosphor particles thus dry-heat-treated may be subjected to secondary heat treatment to maintain sufficient crystal growth and spherical shape, wherein the heat treatment temperature is performed at 800 to 1500 ° C, preferably at 900 to 1250 ° C for 1 to 5 hours. desirable.

According to the method of the present invention, a rare earth metal such as Dy, Sm, Nd, Tm, Pr or Sc is added to the yttrium gadolinium-based phosphor as an activator and ethylene glycol and citric acid are added together to prepare a precursor solution. The (Y _1-abc Gd _a Eu _b M _c ) ₂ O ₃ red phosphor is stable even in a high temperature heat treatment process to maintain a spherical shape, and exhibits excellent luminescence brightness under vacuum ultraviolet rays, and particularly high emission red color of a PDP display. It is suitable as a phosphor.

The invention can be better understood by the following examples, which are intended for the purpose of illustration of the invention and are not intended to limit the scope of protection defined by the appended claims.

Example

In the present invention, at least 30 vibrators, which are droplet generation sites, are connected side by side in the droplet generator, and these droplet generators are connected in parallel. Accordingly, it is possible to generate dozens of droplets per hour, and commercial mass production of phosphor powder by spray pyrolysis is possible. In addition, while the conventional ultrasonic droplet generator is in direct contact with the vibrator and the solution, in the present invention, a polymer film, for example, a polyacetal film blocking film is used to prevent contact between the solution and the vibrator, specifically, to contain the precursor solution The vessel was made of glass or acrylic and a polyacetal film was attached to the bottom thereof. Such a polymer film can be used to semi-permanently because the spray of the droplets is performed well and is very stable to the vibration of the ultrasonic wave.

Example 1 Preparation of (Y _0.38 Gd _0.57 Dy _0.0004 ) ₂ O ₃ : Eu _0.05 Phosphor

As a raw material, a spray solution is prepared by uniformly mixing citric acid and ethylene glycol solution in 0.2M each of nitrates of yttrium (Y), gadolinium (Gd), dysprosium (Dy) and europium (Eu), so that the concentration is 0.5M. Was prepared. At this time, 7.28 g of yttrium nitrate, 12.86 g of gadolinium nitrate, 0.008 g of dysprosium nitrate, 0.88 g of citrate nitrate, 4.20 g of citric acid and 1.24 g of ethylene glycol were dissolved in 100 ml of distilled water so that the total concentration of the precursor solution was 0.5 M. And then mixed.

The resulting solution was placed in an ultrasonic droplet generating device and generated as droplets of about 1 to 10 microns. The resulting droplets were dried and pyrolyzed at a reactor temperature of 800 ° C. to be converted into fine powders. The phosphor particles thus obtained were placed in an alumina boat and heat-treated at 1150 ° C. for 3 hours while flowing air at 45 L / min, followed by dysprosium. Phosphor particles having a doping amount of (Dy) of 0.0004 were prepared. An electron micrograph of this particle is shown in FIG. 2.

Comparative Example 1: Preparation of (Y _0.38 Gd _0.57 ) ₂ O ₃ : Eu _0.05 phosphor

The title compound was prepared in the same manner as in Example 1, except that Dysprosium (Dy) was not used as a starting material, and an electron micrograph of the particle is shown in FIG. 3.

Comparative Example 2: Preparation of (Y _0.38 Gd _0.57 ) ₂ O ₃ : Eu _0.05 phosphor

The title compound was prepared in the same manner as in Comparative Example 1, except that citric acid and ethylene glycol were not added when preparing the spray solution, and an electron micrograph of the particles is shown in FIG. 4.

2, 3 and 4, the phosphor of the present invention (Example 1) prepared by doping the rare earth metal as an activator and adding citric acid and ethylene glycol in the preparation of the spray solution can maintain the spherical shape even after heat treatment. have. The phosphor (Comparative Example 1) to which the polymer is added when preparing the precursor solution without doping the rare earth metal shown in FIG. 3 also has a generally spherical shape, but the phosphor of the present invention (Example 1) has a much more spherical shape. You can see perfection. In addition, phosphors having the same composition as the phosphor of Comparative Example 1 but not containing a polymer due to the addition of citric acid and ethylene glycol (Comparative Example 2) have a hollow or broken form.

Comparative Example 3: Preparation of (Y _0.38 Gd _0.57 ) ₂ O ₃ : Eu _0.05 phosphor

In preparing the spray solution, the title compound was prepared in the same manner as in Example 1, except that citric acid and an aqueous solution of ethylene glycol were not added.

Example 2 Preparation of (Y _0.38 Gd _0.57 Sm _0.0004 ) ₂ O ₃ : Eu _0.05 Phosphor

The title compound was prepared in the same manner as in Example 1, except that samarium (Sm) was used instead of dysprosium (Dy) as the active ingredient.

Example 3: Preparation of (Y _0.38 Gd _0.57 Nd _0.0004 ) ₂ O ₃ : Eu _0.05 phosphor

The title compound was prepared in the same manner as in Example 1, except that neodymium (Nd) was used instead of dysprosium (Dy) as the active ingredient.

Example 4 Preparation of (Y _0.38 Gd _0.57 Tm _0.0004 ) ₂ O ₃ : Eu _0.05 Phosphor Powder

The title compound was prepared in the same manner as in Example 1, except that thulium (Tm) was used instead of dysprosium (Dy) as the active ingredient.

Example 5: Preparation of (Y _0.38 Gd _0.57 Pr _0.0004 ) ₂ O ₃ : Eu _0.05 phosphor

The title compound was prepared in the same manner as in Example 1, except that praseodymium (Pr) was used instead of dysprosium (Dy) as the active ingredient.

Example 6: Preparation of (Y _0.38 Gd _0.57 Sc _0.0004 ) ₂ O ₃ : Eu _0.05 phosphor

The title compound was prepared in the same manner as in Example 1, except that scandium (Sc) was used instead of dysprosium (Dy) as the active ingredient.

Test Example 1: Luminescent Properties

Using the fluorescent materials prepared in Examples and Comparative Examples, the emission spectra under the vacuum ultraviolet region having a wavelength of 500 to 700 nm are shown in FIGS. 5 and 6, respectively.

The doping concentrations of the activator components of the phosphors obtained in Examples 1 to 4, respectively, exhibiting optimal emission luminances were 0.0001M of dysprosium (Dy), 0.0008M of samarium (Sm), 0.0001M of neodymium (Nd), and thulium (Tm), respectively. ) 0.002M.

In the emission spectrum of FIG. 5, the phosphors containing polymers (Examples 1 and 2) were doped with doping agent dysprosium (Dy) and samarium (Sm), and citric acid and ethylene glycol were added to prepare a spray solution. It can be seen that the luminance is increased by 50% or more compared with the phosphor that is not doped with the component (Comparative Example 1). In addition, the luminescence brightness was increased by 25% compared to the phosphor containing the activator but not containing the polymer (Comparative Example 3). This is because the phosphor powders containing the polymer component are filled inside and have a dense structure, so that defects on the surface which reduce the emission intensity of the phosphors are reduced a lot, and such high brightness spherical phosphor powders are more effective than when actually applied to a display or a lamp. Excellent properties.

As shown in FIG. 6, the luminescence intensity of each of the active ingredients neodymium (Nd) and thulium (Tm) was added (Examples 3 and 4) as compared with those without addition (Comparative Example 1), respectively. 47% and 53% increase. Even when Pr and Sc were added as active agent doping materials (Examples 5 and 6), the luminescence intensity increased by about 17% under vacuum ultraviolet rays, respectively, compared with the case without addition, but when Dy, Sm, Nd, and Tm were added. It did not increase as much.

As described above, the yttrium gadolinium-based red phosphor of the present invention is vacuum by adding dysprosium (Dy), samarium (Sm), neodymium (Nd), thulium (Tm), praseodymium (Pr) or scandium (Sc) as active materials. It exhibits high absorption peak in the ultraviolet region, and in particular, by including a polymer material therein, it is stable even in a high temperature heat treatment process and maintains a spherical shape, and has a much superior luminous luminance compared to a conventional red phosphor. It can be applied as a red phosphor.

Claims (8)

Red light emitting phosphor of formula (I): Formula 1 (Y _1-abc Gd _a Eu _b M _c ) ₂ O ₃ In the above formula, M is a rare earth metal selected from Dy, Sm, Nd, Tm, Pr, and Sc, and 0 ≦ a <1, 0.005 ≦ b ≦ 0.2, 0.00001 ≦ c ≦ 0.1. Yttrium (Y) compounds; Gadolinium (Gd) compounds; Europium (Eu) compounds; Rare earth metal compounds selected from dysprosium (Dy), samarium (Sm), neodymium (Nd), thulium (Tm), praseodymium (Pr), and scandium (Sc); And dissolving citric acid and ethylene glycol in a solvent, and then spraying the resulting precursor mixed solution into fine droplets using a droplet generating apparatus to dry and heat treatment at a reactor temperature of 300 to 1500 ° C. to synthesize phosphor powder, and synthesized phosphor powder. Method for producing a yttrium gadolinium-based red light emitting phosphor for vacuum ultraviolet rays of the formula (1) comprising the heat treatment for 1 to 5 hours at 800 to 1500 ℃: Formula 1 (Y _1-abc Gd _a Eu _b M _c ) ₂ O ₃ Wherein M is a rare earth metal selected from Dy, Sm, Nd, Tm, Pr and Sc, and 0 ≦ a <1, 0.005 ≦ b ≦ 0.2, 0.00001 ≦ c ≦ 0.1. The method of claim 2, The yttrium, gadolinium, europium or rare earth metal compound is the respective nitrate, acetate, chloride, oxide or carbonate. The method of claim 2, Characterized in that the total concentration of the precursor mixed solution is from 0.02 to 2M. The method of claim 2, The concentration of citric acid and ethylene glycol solution is 0.01 to 0.5M respectively. The method of claim 2, The diameter of the fine droplets is characterized in that 0.1 to 100㎛. The method of claim 2, And wherein the droplet generating device is selected from the group consisting of an ultrasonic wave, an air nozzle, an ultrasonic nozzle, an electrostatic spraying device, and a filter expanding droplet generating device. A plasma display or a light emitting lamp comprising the yttrium gadolinium-based red phosphor of claim 1 in a light emitting layer.