KR100785089B1 - The blue phosphor of cacium strontium magnesium silicate and preparation method thereof - Google Patents

Abstract

A blue phosphor based on calcium strontium magnesium silicate is provided to obtain spherical micropowder having a micrometer size, showing a high absorption peak in a long UV range of 380-420 nm, and useful for a high-efficiency blue phosphor in a UV light emitting diode. A blue phosphor based on calcium strontium magnesium silicate is represented by the formula of (Ca1-xSrx)(1-y)Mg3Si4O12 : Eu2+y, wherein 0<x<1 and 0.005<=y<=0.2. The blue phosphor is spherical particle. The blue phosphor is obtained by the method comprising the steps of: dissolving a Ca precursor, Mg precursor, Si precursor, Sr precursor and Eu precursor in a predetermined ratio to obtain a precursor spraying solution; atomizing the precursor spraying solution into fine liquid drops; drying and pyrolyzing the fine liquid droplets at 500-12000 deg.C.; and firing the resultant phosphor powder under a reductive atmosphere at 900-1350 deg.C.

Description

The Blue Phosphor of Cacium Strontium Magnesium Silicate And Preparation Method Thereof}

Figure 1 shows a schematic diagram of the spray pyrolysis process apparatus according to the present invention.

Figure 2 shows the excitation and emission spectrum of the CaMg ₃ Si ₄ O ₁₂ : Eu _0.03 phosphor prepared in Comparative Example 1.

Figure 3 shows the excitation and emission spectra of the (Ca _0.5 Sr _0.5 ) Mg ₃ Si ₄ O ₁₂ : Eu _0.03 phosphor prepared in Example 1 according to the present invention.

FIG. 4 shows excitation and emission spectra of (Ca _0.5 Sr _0.5 ) Mg ₃ Si ₄ O ₁₂ : Eu _0.03 phosphor prepared using 20 mol% NH ₄ Cl flux in Example 2 according to the present invention.

Figure 5 shows a comparative emission spectrum of the phosphor prepared in Comparative Examples and Examples 1 and 2 in accordance with the present invention.

Figure 6 shows an electron scanning microscope (SEM) photograph of the phosphor prepared in Example 1 according to the present invention.

The present invention relates to a calcium strontium magnesium silicate-based blue phosphor and a method for manufacturing the same, and more particularly, to a novel composition comprising a matrix composed of calcium, magnesium, strontium and silicon, and an active agent of +2 valent europium in a fixed ratio. The present invention relates to a calcium strontium magnesium silicate-based blue phosphor having a blue phosphor having a spherical microparticle having a micron-sized spherical fine particle, which is prepared by a spray pyrolysis process and has excellent luminescence at an excitation wavelength in the range of 380 to 420 nm.

Recently, a white light emitting diode device, which has been spotlighted as an LCD back light source for lighting, laptops, and mobile phones, is classified into two types.

The first type produces white by mixing YAG-based phosphors emitting yellow light to the blue LED, and the second type combines blue, green, and red phosphors with UV LEDs to achieve white. It is.

Specific examples of these are as follows. Korean Patent Laid-Open Publication No. 2000-0049728 discloses a YAG: Ce phosphor in which a part of yttrium of yttrium aluminum garnet (Y ₃ Al ₅ O ₁₂ ) is substituted with cerium, which is a white light of a white LED whose GaN blue light is the excitation source. It is described as suitable for implementation. However, white LEDs using GaN-based blue LEDs as excitation sources are not satisfactory in terms of luminous efficiency and color rendering.

In order to expand the application of white LED to general lighting, improvement of luminous efficiency and color rendering is essential, and in order to solve the problem of white LED based on existing blue LED, we want to develop white LED with higher efficiency by using UV LED. Research is actively underway.

In order to develop the second type of UV LED and enter the market, it is urgent to develop blue, red and green phosphors having excellent luminous efficiency in the excitation source in the range of 380 to 420 nm. In addition, it is necessary to optimize the emission characteristics through controlling the particle size and shape of the phosphor, to control the UV emission characteristics harmful to the human body, and to evaluate and improve the thermal and chemical stability characteristics of the phosphor.

The technology of synthesizing phosphor having excellent light emission characteristics is an essential core technology for completing LED manufacturing technology. The process commercialized so far uses a solid phase method, but the solid phase method has a problem in controlling the particle size of the phosphor, and also produces a phosphor having a size of several to several tens of microns or more. In order to design high quality LED using UV LED and effectively block UV harmful to human body, it is necessary not only to have high brightness characteristics but also to have fine and uniform size for high quality product design. In this respect, the existing solid phase method does not provide a synthesis method for a suitable phosphor.

Thus, the present inventors have tried to solve the above problems. As a result, a blue phosphor having a novel composition composed of a matrix composed of calcium, strontium, magnesium, and silica, a activator of europium in a constant ratio, and spray pyrolysis, which is one of the gas phase synthesis methods in the preparation of the blue phosphor, are applied. The present invention has been completed by knowing that it is possible to prepare micron-sized spherical fine powder.

Accordingly, an object of the present invention is to provide a method for preparing the same using a calcium strontium magnesium silicate-based blue phosphor and a spray pyrolysis process.

The present invention is characterized by a calcium strontium magnesium silicate-based blue phosphor represented by the following formula (1).

(Ca _1-x Sr _x ) _{( 1-y )} Mg ₃ Si ₄ O ₁₂ : Eu ²⁺ _y

In Formula 1, 0 <x <1 and 0.005 ≦ y ≦ 0.2.

In this case, when strontium is not contained in the chemical formula, the emission luminance is low, which is not preferable. Preferably, the calcium and the strontium maintain 0.5, that is, x is 0.5. In this case, the emission luminance under long wavelength ultraviolet rays has the highest efficiency. In addition, if the amount of doping y of the europium is less than 0.005, the amount of the activator is too small, the emission luminance is lowered, and if it exceeds 0.2, the luminance decreases due to the concentration quenching phenomenon.

In addition, the present invention comprises the steps of dissolving the calcium precursor, magnesium precursor, silicon precursor, strontium precursor and europium precursor in a quantitative range to prepare a precursor spray solution;

Generating the spray solution into microdroplets;

Synthesizing a phosphor powder by drying and thermally decomposing the microdroplets in a temperature range of 500 to 1200 ° C .; And

The synthesized phosphor powder is further characterized by a method for producing a calcium strontium magnesium silicate-based blue phosphor represented by the formula (1) comprising the step of firing at a temperature ranging from 900 to 1350 ° C. under a reducing atmosphere.

Hereinafter, the present invention will be described in detail.

The present invention relates to a highly efficient blue phosphor having a main emission peak in the range of 430 to 460 nm at an excitation wavelength in the range of 380 to 420 nm. Specifically, using a calcium precursor, magnesium precursor, silicon precursor, strontium precursor and europium precursor in the quantitative range by the spray pyrolysis process has a main emission peak in the range of 430 ~ 460 nm in the excitation wavelength range of 380 ~ 420 nm It is a blue phosphor which has a spherical several micrometer particle size.

In general, blue phosphors containing calcium, magnesium, strontium and silicon precursors as parent components are known. However, even if the same component is used, the type of the phosphor is completely different according to the difference in its composition ratio, and the luminescent property is also markedly different. As a result, the blue phosphor having the composition ratio according to the present invention is a novel substance which is not known yet. Can be.

Looking at the manufacturing method of the blue phosphor according to the present invention in more detail as follows.

First, calcium precursor, magnesium precursor, silicon precursor, strontium precursor and europium precursor are dissolved in a quantitative range to prepare a precursor spray solution. At this time, the spray solution may further contain a flux component.

The precursors of calcium, magnesium, europium and strontium are preferably water-soluble and acid soluble materials. Specifically, one or a mixture of two or more selected from nitrates, acetates, chlorides, oxides, and carbonates may be used. Can be. The silicon precursor is capable of maintaining a solution state (precipitating and not sinking) when mixed with a solution containing the above metal components and stable in an air atmosphere, and is tetraethyl orthosilicate (TEOS) or silica powder. , Silica powder may be used that can maintain a transparent solution state when dispersed in an aqueous solution of silica nanoparticles having a particle size of several nm.

At the time of dissolution, a spray solution is prepared using distilled water, an alcoholic organic solvent having 1 to 6 carbon atoms, or a mixed solvent thereof. In this case, the solvent is used so that the concentration of the finally formed phosphor component is maintained in the concentration range of 0.1 ~ 2 M, if the amount of the solvent is used a lot so that the amount of the solution is less than 0.1 M, the productivity is too low, the solution In the case where the solvent is used so that the concentration of is greater than 2 M, the viscosity of the solution becomes high and spraying occurs. Therefore, it is preferable to maintain the above range.

Next, the spray solution is generated as microdroplets.

The present invention uses a spray pyrolysis method of spraying the spray solution into droplets to synthesize phosphor particles through drying and pyrolysis in a gaseous atmosphere. The spray pyrolysis method enables uniform synthesis of the composition and low temperature firing, and since the shape control of the phosphor particles is relatively simple as compared with the general solid state method or the liquid phase method, phosphor particles having a more regular shape can be obtained, and thus, When applied, the coating and luminescent properties are excellent.

1 is a schematic diagram of a spray pyrolysis process apparatus, which is composed of an ultrasonic droplet generator, a tubular reactor for drying and pyrolyzing droplets, a filter for particle recovery, and the like. In this case, the droplet generator may use an ultrasonic wave, an ultrasonic nozzle, and an air nozzle. The droplets of several to several tens of microns in size are sprayed into the reactor by the carrier gas, and spherical precursor powders are obtained by drying and pyrolysis. At this time, the drying temperature is preferably maintained in the range of 500 to 1200 ° C, preferably in the range of 700 to 1000 ° C.

The obtained phosphor powder is calcined under a reducing atmosphere. At this time, the firing temperature is preferably performed at 900 to 1350 ℃, preferably 1000 to 1300 ℃, more preferably about 1200 ℃, 1 to 10 hours, preferably 4 to 6 hours. If the firing temperature is less than 900 ℃ when the reduction of the europium activator is not completed and exceeds 1350 ℃ it is preferable to maintain the above range because aggregation occurs between the phosphor particles.

In addition, the firing is carried out under a reducing atmosphere, in which 1 to 25% by volume of hydrogen, 75 to 99% by volume of nitrogen, preferably 4 to 7% by volume of hydrogen, and 96 to 93% by volume of nitrogen are mixed. It is preferably carried out under gas. At this time, the mixed gas is used at a flow rate in the range of 800 ~ 1000 mL / min. In this process, the europium is reduced from trivalent to divalent.

In addition, before performing the firing process in the reducing atmosphere, the heat-treated phosphor particles are subjected to secondary heat treatment at 700 to 1300 ° C for 0.5 to 10 hours, preferably at 900 to 1200 ° C for 1 to 3 hours in an oxygen or air atmosphere. Can be done.

The present invention uses flux to reduce the reaction temperature and shorten the time. In addition to the general features described above, synthesizing the phosphor using flux is effective in improving the crystallinity of the phosphor by improving the crystallinity. Such flux may be specifically used NH ₄ Cl, LiCl and H ₃ BO ₃ and the like. The flux is preferably 5 to 100 mol%, preferably 10 to 30 mol%, based on the total precursor.

Calcium strontium magnesium silicate-based blue phosphor prepared according to the present invention is improved in the luminescence intensity by 330% or more in the long wavelength ultraviolet range of 380 to 420 nm compared to the calcium magnesium silicate blue phosphor excluding strontium, and furthermore the present invention When the phosphor was prepared by adding an appropriate amount of flux to the phosphor composition, the emission intensity was improved by 390%.

That is, the blue phosphor according to the present invention has excellent light emission characteristics in the excitation wavelength in the range of 380 to 420 nm, and has a spherical microparticle having a micron size, and thus, a blue light emitting diode, a white light emitting diode, and a backlight for display using the same Or it is easy to apply to lighting equipment.

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

Comparative Example 1: CaMg ₃ Si ₄ O ₁₂ Eu ²⁺ _0.03  Preparation of Phosphor

Tetraethyl Orthosilicate (TEOS), CaCl ₂ · 2H ₂ O, MgCl ₂ · 6H ₂ O, and Europium oxide (Eu ₂ O ₃ ) are uniformly mixed in distilled water using a small amount of nitric acid Spray solution was prepared to be 1M. The generated spray solution was placed in an ultrasonic droplet generating device, and generated as a fine droplet of about 5 μm. The generated droplets were dried and pyrolyzed at a reactor temperature of 900 ° C. to convert to a fine powder. The converted phosphor particles were put in an alumina boat, and flow was mixed at 400 mL / min for 5% by volume of hydrogen / 95% by volume of nitrogen, and the atmosphere was formed such that europium (Eu) was reduced from trivalent to 2 horizontally at 1200 ° C. It was calcined for 5 hours at to prepare a CaMg ₃ Si ₄ O ₁₂ : Eu ²⁺ _0.03 phosphor.

Example 1 (Ca _0.5 Sr _0.5 Mg ₃ Si ₄ O ₁₂ Eu ²⁺ _0.03  Preparation of Phosphor

Tetraethyl Orthosilicate (TEOS), CaCl ₂ · 2H ₂ O, MgCl ₂ · 6H ₂ O, SrCl ₂ · 6H ₂ O, Europium oxide (Eu ₂ O ₃ ) with distilled water The spray solution was prepared by uniformly mixing in a concentration of 1 M. The generated spray solution was placed in an ultrasonic droplet generating device, and generated as a fine droplet of about 5 μm. The generated droplets were dried and pyrolyzed at a reactor temperature of 900 ° C. to convert to a fine powder. The converted phosphor particles were placed in an alumina boat, and flow was mixed at 400 mL / min for 5% by volume of hydrogen / 95% by volume of nitrogen, and the atmosphere was formed such that europium (Eu) was reduced from trivalent to divalent at 1200 ° C. The (Ca _0.5 Sr _0.5 ) Mg ₃ Si ₄ O ₁₂ : Eu ²⁺ _0.03 phosphor was prepared by calcination for 5 hours at.

Example 2: Flux (Ca _0.5 Sr _0.5 Mg ₃ Si ₄ O ₁₂ Eu _0.03 ²⁺  Preparation of Phosphor

In the same manner as in Example 1, 20 mol% of flux NH ₄ Cl was added to the spray solution to prepare a (Ca _0.5 Sr _0.5 ) Mg ₃ Si ₄ O ₁₂ : Eu _0.03 ²⁺ phosphor.

Test Example 1: Luminescent Properties

Using the phosphors prepared in Comparative Examples 1 and 1 and 2, an excitation spectrum in the range of 220 to 430 nm when the emission wavelength was 450 nm, and an emission spectrum when the 405 nm ultraviolet light was emitted using an excitation energy source were used. The measurement results are shown in the following Figures 2, 3, 4, 5 and 6, respectively.

Next, FIG. 2 illustrates excitation and emission spectra of the CaMg ₃ Si ₄ O ₁₂ : Eu _0.03 phosphor prepared in Comparative Example 1, and it was confirmed that the excitation spectrum exhibits a wide distribution in the range of 300 to 430 nm.

3 shows excitation and emission spectra of the (Ca _0.5 Sr _0.5 ) Mg ₃ Si ₄ O ₁₂ : Eu _0.03 phosphor prepared in Example 1 according to the present invention, and the excitation spectrum has a wide distribution from 250 to 430 nm. In particular, it was confirmed that a high energy absorption band was observed in the long wavelength region of 380 to 420 nm.

4 shows excitation and emission spectra of (Ca _0.5 Sr _0.5 ) Mg ₃ Si ₄ O ₁₂ : Eu _0.03 phosphors using NH ₄ Cl plus 20 mol% in Example 2 according to the present invention. It was confirmed that a broad distribution was shown from 250 to 430 nm, and high energy absorption band was observed especially in the long wavelength region of 380 to 420 nm.

Next, Figure 5 shows a comparative emission spectrum of the phosphors prepared in Comparative Example 1 and Examples 1 to 2 according to the present invention, b is the increase in luminescence intensity of 330% compared to a, c is 390% compared to a Luminous intensity increased.

6 shows a scanning electron microscope (SEM) photograph of the phosphor prepared in Example 1 according to the present invention, and the particles of the phosphor were about 3 μm in size.

As described above, the present invention is a calcium strontium magnesium silicate-based blue phosphor of a new composition prepared by mixing in a quantitative ratio using a calcium precursor, a magnesium precursor, a silicon precursor, a strontium precursor and a europium precursor, wherein the blue phosphor is 380 It has a high absorption peak in the long wavelength ultraviolet region of ˜420 nm and is easy to apply as a highly efficient blue fluorescent material of an ultraviolet light emitting diode.

Claims (8)

Calcium strontium magnesium silicate-based blue phosphor, characterized by the following formula (1): [Formula 1] (Ca _1-x Sr _x ) _{( 1-y )} Mg ₃ Si ₄ O ₁₂ : Eu ²⁺ _y In Formula 1, 0 < x <1, and 0.005 ≦ y ≦ 0.2. The blue phosphor according to claim 1, wherein the blue phosphor is a spherical particle. Preparing a precursor spray solution by dissolving a calcium precursor, a magnesium precursor, a silicon precursor, a strontium precursor, and a europium precursor in a quantitative range; Generating the spray solution into microdroplets; Synthesizing a phosphor powder by drying and thermally decomposing the microdroplets in a temperature range of 500 to 1200 ° C .; And Method for producing a calcium strontium magnesium silicate-based blue phosphor represented by the formula (1) comprising the step of firing the synthesized phosphor powder at a temperature range of 900 ~ 1350 ℃ under a reducing atmosphere: [Formula 1] (Ca _1-x Sr _x ) _{( 1-y )} Mg ₃ Si ₄ O ₁₂ : Eu ²⁺ _y In Formula 1, 0 < x <1, and 0.005 ≦ y ≦ 0.2. The method of manufacturing a blue phosphor according to claim 3, wherein flux is used in the spray solution in a range of 5 to 100 mol% based on the total precursor. The method of claim 4, wherein the flux is selected from NH ₄ Cl, LiCl, and H ₃ BO ₃ . A blue light emitting diode comprising any one of calcium magnesium silicate-based blue phosphors selected from claims 1 to 2. A white light emitting diode comprising any one of calcium magnesium silicate-based blue phosphors selected from claims 1 to 2. Display backlight or illuminator containing the white light emitting diode of claim 7.

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