KR101420978B1 - An apparatus for synthesizing phospor using dielectric barrier discharge and a method using the same - Google Patents

Abstract

The present invention relates to a phosphor synthesizing apparatus using dielectric barrier discharge comprising: a first reactor synthesizing the phosphor and arranged to accommodate a powder raw material; a cover positioned at an upper part of the first reactor for applying a voltage; a first internal electrode and a first external electrode arranged in the first reactor; a second internal electrode and a second external electrode arranged in the cover; and a second reactor heating the first reactor and arranging a tube at the inside. Additionally, the present invention relates to a phosphor synthesizing method using the dielectric barrier discharge comprises the steps of: (a) mixing a bulb material in the first reactor, obtaining a pellet and covering the first reactor by a cover; (b) moving the first reactor into a second reactor via a tube; (c) applying a power source to the second reactor and heating the first reactor to the temperature of 1200-1400°C by the second reactor; and (d) cooling the heated first reactor at the temperature of 20-30°C and obtaining the phosphor pellet. More, the present invention relates to phosphor powders obtained by crushing the phosphor pellet of Sr_2SiO_4:Eu^2^+ obtained though the phosphor synthesizing method.

Description

FIELD OF THE INVENTION The present invention relates to a phosphor synthesizing apparatus using a dielectric barrier discharge and a method for synthesizing a phosphor.

The present invention relates to a fluorescent material synthesizing apparatus using a dielectric barrier discharge and a method of synthesizing a fluorescent material.

Display devices, which are the most direct mediators of information transfer, have the advantage of providing the most natural images because they form information through light emitting materials (phosphors) excited by electrons or photons. Here, a light emitting material, that is, a phosphor refers to a substance that absorbs external energy to emit visible light, and a phenomenon that emits visible light is referred to as light emission.

LED (Light Emitting Diode) is a semiconductor device that emits light, and is used in various electronic products and electronic display boards. LEDs are light emitting devices that can be driven at low voltage and have a longer lifetime, lower power consumption, faster response speed, and higher impact resistance than other light emitting devices. In addition, there is an advantage in that it can be made compact and lightweight, and applications are increasingly centered on display applications. LEDs can control light of different wavelengths depending on the type of materials and constituent materials, and there is an opportunity to create new markets according to different wavelengths of light. Since the phosphor is the main factor that determines the brightness, lifetime, and reliability of the LED, the characteristics of the phosphor itself are very important.

Conventionally, Sr ₂ SiO ₄ : Eu ^{2 +} green phosphors are synthesized with a high temperature of 1375 ° C. and a long high-temperature retention time of 3 hours. This means that enormous energy is consumed and the size of a device for heating to a high temperature is inevitable Lt; / RTI >

KR 2010-0114998 (publication number)

Accordingly, it is an object of the present invention to provide an apparatus and a method for synthesizing a Sr ₂ SiO ₄ : Eu ^{2 +} green phosphor exhibiting enhanced light emission efficiency by using a dielectric barrier discharge.

The present invention relates to a phosphor synthesis apparatus using a dielectric barrier discharge, comprising: a first reactor equipped with a phosphor synthesis and containing a powder raw material; A cover positioned above the first reactor for applying a voltage thereto; A first inner electrode and a first outer electrode provided in the first reactor; A second internal electrode and a second external electrode provided on the cover; A second reactor for heating the first reactor and having a tube therein; Wherein the Sr ₂ SiO ₄ : Eu ²⁺ phosphor is a rare ^earth metal.

The present invention also provides a method of synthesizing a phosphor using a dielectric barrier discharge, comprising the steps of: (a) mixing precursors in a first reactor to obtain pellets and then covering the pellets with a lid; (b) introducing the first reactor into a second reactor through a tube; (c) applying power to the second reactor to heat the introduced first reactor to a temperature in the second reactor to a temperature of 1200 to 1400 ° C; And (d) cooling the heated first reactor to 20 to 30 占 폚 to obtain a phosphor sintered body; And a method of synthesizing the phosphor.

Also provided is a Sr ₂ SiO ₄ : Eu ²⁺ phosphor powder obtained by pulverizing a phosphor sintered body obtained by the method for synthesizing a phosphor.

The present invention can synthesize a Sr ₂ SiO ₄ : Eu ^{2 +} phosphor by lowering the synthesis temperature by heating the first reactor with a second reactor having a tube therein and applying a dielectric barrier discharge during the firing process of the green phosphor The synthesis time of Sr ₂ SiO ₄ : Eu ^{2 +} green phosphor can be shortened.

FIG. 1 (A) is a front view of a phosphor synthesizing apparatus according to the present invention, and FIG. 1 (B) is a side view of a phosphor synthesizing apparatus according to the present invention.
2 is a schematic diagram of an experimental apparatus for an embodiment of the present invention.
3 is a graph showing a voltage value corresponding to 20 W according to temperature.
4 is a schematic diagram of the reaction of the present invention.
5 is a graph comparing the photoluminescence values of the Sr ₂ SiO ₄ : Eu ^{2 +} green phosphor with respect to the plasma discharge.

In the present invention, an apparatus for activating a reaction using a dielectric barrier discharge device to synthesize a Sr ₂ SiO ₄ : Eu ^{2 +} green phosphor within a shorter synthesis time and a short synthesis time, and to exhibit a higher photoluminescence value ≪ / RTI >

The present invention relates to a Sr ₂ SiO ₄ : Eu ^{2 +} phosphor synthesizing apparatus using a dielectric barrier discharge, comprising: a first reactor in which a phosphor is synthesized; A cover positioned above the first reactor for applying a voltage thereto; A first inner electrode and a first outer electrode provided in the first reactor; A second internal electrode and a second external electrode provided on the cover; And a second reactor for heating the first reactor and having a tube therein; .

More specifically, the second reactor of the present invention may have a space in which a tube can be inserted, and a tube may be included in the space. The tube may also be tubular. As an example, a tube having an inner diameter of 60 mm, an outer diameter of 70 mm, and a length of 1000 mm was used.

The first reactor, the lid and the tube may be made of firing. Here, firing means a property that does not deform even when a small external force is applied to an object, deforms when an external force is applied to some extent, and does not return to the original shape even when an external force is removed.

Further, the first external electrode and the second external electrode may be a Sr ₂ SiO ₄ : Eu ^{2 +} phosphor synthesizing device having a ground portion.

Particularly, in the electrode of the present invention, flat plate type molybdenum is used as an example.

The electrode means the first internal electrode, the first external electrode, the second internal electrode, and the second external electrode in the present invention.

Referring to FIG. 1, the electrode of the present invention is provided in a first reactor and a cover. The electrodes provided on the cover may be the first internal electrode and the first external electrode, and the electrodes provided in the first reactor may be the second internal electrode and the second external electrode.

Further, the present invention may further include a power source, and the power source may generate a plasma by supplying a current to the external electrode.

In addition, when the sintering is performed by applying current to the phosphor powder raw material of the present invention, a plasma discharge is generated between the particles due to excessive current at the initial stage of sintering and high heat is generated. This heat causes the neck to be formed at the contact point between the particles, which leads to Joule heating by electric current. As a result, heat can start to be generated in the specimen itself, and as the sintering progresses, the plasma no longer occurs, but the specimen can be made more dense by the applied current.

More particularly, the present invention relates to a method of synthesizing a Sr ₂ SiO ₄ : Eu ^{2 +} phosphor using a phosphor synthesizer, and more particularly, to a method of synthesizing a phosphor using a dielectric barrier discharge, comprising the steps of: (a) Obtaining a pellet and then covering the pellet with a cover; (b) introducing the first reactor into a second reactor through a tube; (c) applying power to the second reactor to heat the introduced first reactor to a temperature in the second reactor to a temperature of 1200 to 1400 ° C; And (d) cooling the heated first reactor to 20 to 30 占 폚 to obtain a phosphor sintered body; .

In particular, the precursors are characterized by comprising SrCO ₃ , SiO ₂ , Eu ₂ O ₃ and NH ₄ Cl. More specifically, SrCO ₃ , SiO ₂ And Eu ₂ O ₃ may be molar fractions (0.003? X? 0.05) of (2-x), 1, (x / 2) and may contain a trace amount of NH ₄ Cl. In particular, the Sr ₂ SiO ₄ : Eu ^{2 +} phosphor can be synthesized using the solid state reaction method.

Here, the solid-phase reaction method refers to a method of obtaining powder of a desired composition by mixing two or more kinds of oxides, carbonates, and the like to cause a reaction between solids at a high temperature.

The Eu ₂ O ₃ is an activator that receives energy from the outside and emits visible light.

In addition, the phosphor powder raw material may further include a sensitizer.

Herein, when the chemical reaction or the physical phenomenon is remarkably accelerated by adding a small amount of a substance in the chemical reaction system or the material system, the additive is referred to as a sensitizer, and the sensitizer is capable of converting the energy received from the silicate host crystal A role of transferring it to an activator, and a role of increasing a conductivity of a phosphor.

In the step (b), 350 to 450 sccm of argon or nitrogen gas is injected into the tube. The inside of the tube was used for plasma discharge. For example, argon gas was injected at 400 sccm to form an argon gas atmosphere.

In the step (c), the first reactor may be heated to a temperature of 4 to 6 ° C / minute or 5 ° C / minute, and the temperature may be raised to 1200 ° C to 1400 ° C or 1275 ° C to 1325 ° C.

And when the temperature is reached, the temperature condition is maintained for 0 to 2 hours.

If the temperature is less than 1200 ° C, the synthesis is not performed at all. If the temperature exceeds 1400 ° C, the sintered body becomes a high-density sintered body and can be in a molten state.

In particular, the first reactor may include a step of injecting hydrogen gas at a temperature of 550 to 600 ° C at a rate of 80 to 120 sccm; And a step of injecting a mixed gas of 75 to 85% of Ar and 15 to 20% of H _2. More specifically, in order to form a reducing atmosphere at 550 to 600 ° C. or 550 ° C. when the temperature is raised 80sccm, and to inject the hydrogen gas of 120sccm 100sccm or, when Ar is 75% to 85%, H ₂ And injecting a mixed gas of 15% to 25%. For example, Ar 80%, H ₂ 20% mixed gas was injected.

In particular, the step (c) of the present invention may cause a plasma discharge by applying a voltage from 550 ° C to 650 ° C when the temperature is raised. For example, a voltage was applied at 600 ° C.

In addition, when the temperature reaches 550 ° C to 650 ° C during the cooling process in the step (d) of the present invention, the voltage application can be stopped. For example, when the temperature reached 600 ° C during the cooling process, the voltage application was stopped.

Also, a high voltage power source is applied to the inner electrode and the outer electrode, and the voltage may be 1.47 kV to 8.27 kV.

The present invention also relates to a phosphor powder obtained by pulverizing a phosphor sintered body obtained by the Sr ₂ SiO ₄ : Eu ^{2 +} phosphor synthesis method.

< Example >

Example  1. Dielectric Barrier  Using discharge Sr ₂ SiO ₄ : Eu ^{2 +}  Green phosphor synthesis.

To prepare the Sr ₂ SiO ₄ green phosphor in which Eu is doped, a of the phosphor powder raw materials _{SrCO 3 (Aldrich, 99.9%)} , SiO 2 (Aldrich, 99.995%) , and _{Eu 2 O 3 (Aldrich, 99.99} %) each 1.99 , 1, 0.005 mol% and a trace amount of NH ₄ Cl (Aldrich, 99.998%) were mixed to prepare 1 g of pellets, thereby preparing five phosphor raw material pellets. The phosphor raw material pellet was placed on the lower part of the first reactor, and the cover of the upper part was covered. An internal electrode was placed on the lower part of the first reactor and connected to the ground. A molybdenum electrode was placed on the upper part of the reactor, and the high voltage was applied to the alumina tube of the second reactor. The temperature was raised to the second reactor at a rate of 5 ℃ / min, maintained for 2 hours at a temperature of 1275 to 1325 ℃ ℃ was then cooled to room temperature and Sr ₂ SiO _4: Eu ^{2 +} green phosphor was prepared. FIG. 4 shows the reaction scheme of the embodiment of the present invention.

5 is a photoluminescence spectrum of Sr ₂ SiO ₄ : Eu ^{2 +} green phosphor. The excitation wavelength of the photoluminescence spectrum is 450 nm, and has the maximum emission intensity at 518 nm. (a) represents the photoluminescence of the phosphor synthesized by the conventional sintering method, and the synthesis temperature is 1375 ° C., which represents a treatment time of 3 hours. (B), (c) and (d) show the photoluminescence of the phosphor synthesized by the method of the present invention, and the synthesis temperature is 1325 ° C., which represents the processing time of 0, 1, and 2 hours, respectively.

The embodiments described above are intended to illustrate the contents of the present invention and are not intended to limit the scope of the present invention. Embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art.

100: first reactor
110: second internal electrode 120: second external electrode
200: Cover
210: first inner electrode 220: first outer electrode
300: raw material

Claims (12)

In a phosphor synthesizer using a dielectric barrier discharge,
A first reactor in which phosphor synthesis is performed;
A cover positioned above the first reactor for applying a voltage thereto;
A first inner electrode and a first outer electrode provided in the first reactor;
A second internal electrode and a second external electrode provided on the cover; And
A second reactor for heating the first reactor and having a tube therein; Wherein the Sr ₂ SiO ₄ : Eu ²⁺ phosphor is synthesized. The method according to claim 1,
Sr ₂ SiO _4, characterized in that, consisting of the first reactor, and the cover is a plastic tube: Eu ^{2 +} phosphor synthesizer. The method according to claim 1,
A first external electrode and second external electrode is Sr ₂ SiO _4, which is characterized by being a ground part: Eu ²⁺ phosphor synthesizer. A method of synthesizing a phosphor using a dielectric barrier discharge,
(a) mixing precursors in a first reactor to obtain pellets and then covering them with a lid;
(b) introducing the first reactor into a second reactor through a tube;
(c) applying power to the second reactor to heat the introduced first reactor to a temperature in the second reactor to a temperature of 1200 to 1400 ° C; And
(d) cooling the heated first reactor to 20 to 30 캜 to obtain a phosphor sintered body; Eu ^{2 +} phosphor synthesis method: Sr ₂ SiO _4, which comprises a. 5. The method of claim 4,
The precursor _{SrCO 3, SiO 2, Eu 2} O 3 and NH ₄ Cl Sr ₂ SiO characterized in that comprises a _4: Eu ²⁺ phosphor synthesis methods. 5. The method of claim 4,
The precursor may be SrCO ₃ , SiO ₂ And Eu ₂ O ₃ are synthesized using a solid phase reaction method with molar fractions (0.003? X? 0.05) of (2-x), 1, (x / 2), Sr ₂ SiO ₄ : Eu ²⁺ Phosphor synthesis method. 5. The method of claim 4,
The step (b) Sr ₂ SiO _4, characterized in that to inject argon or nitrogen gas of 350 to 450sccm in the inside of the tube: Eu ^{2 +} phosphor synthesis methods. 5. The method of claim 4,
Wherein the step (c) Sr ₂ SiO _4, characterized in that for heating the first reactor 4 to 6 ℃ / min: Eu ^{2 +} phosphor synthesis methods. 9. The method of claim 8,
Injecting hydrogen gas at a temperature of 550 to 600 DEG C at a rate of 80 to 120 sccm; And injecting the Ar 75 to 85%, H ₂ 15 to 20% mixture of gases; Sr ₂ SiO ₄ containing: Eu ^{2 +} phosphor synthesis methods. 5. The method of claim 4,
The step (c) is 650 to 550 ℃ Sr ₂ SiO, wherein causing a plasma discharge by applying a voltage from ℃ _4: Eu ^{2 +} phosphor synthesis methods. 5. The method of claim 4,
The step (d) is 550 ℃ to when it reaches the 650 ℃ Sr ₂ SiO, characterized in that to stop the voltage application _4: Eu ^{2 +} phosphor synthesis methods. A Sr ₂ SiO ₄ : Eu ^{2 +} phosphor powder obtained by pulverizing a phosphor sintered body obtained by the method according to any one of claims 4 to 11.

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