KR100950418B1 - Ln3Al5O12:Ce based fluorescent material and manufacturing method of the same - Google Patents

Abstract

The present invention relates to a yellow phosphor for use in conjunction with a blue LED to implement a white LED, and more particularly, to an aluminum garnet-based and to a yellow phosphor added with Ce. These materials are single crystals and polyhedrons with distinct shapes. The garnet phosphor of the present invention has a different crystal structure from the conventional garnet system, and thus has excellent light emission characteristics in the red region and excellent light emission efficiency. The present invention also proposes a method for producing a garnet-based phosphor having such a polyhedral crystal structure.

In the present invention, a compound represented by the following <Formula 1> has a single crystal structure of a polyhedron, the minimum size of the particles of a single crystal is at least 200nm or more, characterized in that the garnet-based crystal phosphor for white LED and its manufacturing method are provided do.

<Formula 1>

Ln ₃ Al ₅ O ₁₂ : Ce

Where Ln is any one selected from the group of rare earth elements consisting of Sm, Tb

 Blue LED, white LED, solid state lighting, garnet phosphor, polyhedral crystal phosphor, precursor, aluminum alkoxide, inorganic salt, organic salt, fluorescence absorption peak, fluorescence excitation peak, fluorescence wavelength, red shift, rare earth element, Nanocrystals, Yttrium, Aluminum, Cerium, Precursor Mixture, Solvothermal Reaction, Crystal Growth, Color Index, Color Temperature

Description

Garnet-based crystal phosphor for white LEDs and a method of manufacturing the same {Ln3Al5O12: Ce based fluorescent material and manufacturing method of the same}

The present invention relates to a phosphor of a light emitting diode (LED), and more particularly, to a yellow phosphor having a polyhedral crystal structure for a white LED, in which the color index, color temperature, and luminescence properties are remarkably improved than before. It is about.

A light emitting diode (LED) is a kind of semiconductor device that emits light by flowing a current through a compound such as gallium, arsenic, and the like, and is used in small flickering lights, large electronic displays, and TV remote controls of various electronic devices. These LEDs consume only about 20% of incandescent bulbs and have a lifetime of 100,000 hours (100 times that of fluorescent lamps), which means that once installed, they require little replacement or maintenance. At present, the high-brightness LED that is attracting attention is a blue LED and a white LED, which is used as a backlight source of a mobile phone keypad and LCD liquid crystal display. In addition, white LEDs can be used as indoor lighting fixtures, produced by Nichia in Japan, HP in the US, and OSRAM in Germany. Compared with conventional light sources, white LEDs have a smaller power consumption, a semi-permanent lifetime, and no preheating time, resulting in a faster response speed, less emission of harmful radiation such as ultraviolet rays, and no mercury or discharge gas. It is expected to be a friendly lighting source.

To implement white LED that emits white light, a single-chip method of combining white or blue LED lamp with fluorescent material and white LED by combining two LEDs complementary to each other or combining several LED chips to obtain white There is a multichip method. When the white light is implemented by the latter method, there is a problem that it is difficult to generate desired white color due to dispersion of color tone or brightness of the light emitting device (LED), and when the light emitting devices are formed of different materials, the driving power of each light emitting device Since there is a need to apply a predetermined voltage to each element due to the difference, the driving circuit is complicated. In addition, since the light emitting device is a semiconductor light emitting device, there are problems such as color tone change due to different temperature characteristics and changes over time, and color tone may vary depending on the usage environment, or the light generated by each light emitting device may not be uniformly mixed. .

In order to solve the problems of the above-described multi-chip type white light implementation method, Japanese Patent Application Laid-Open No. 5-152609, Japanese Patent Laid-Open No. 7-99345, Japanese Patent Laid-Open No. 7-176794, etc. filed by Nichia in Japan As a white LED, a light emitting device capable of emitting blue light is disclosed, and a white LED realization technology capable of emitting white light by molding a resin that absorbs light emission and emits yellow light is emitted to the light emitting device.

In the conventional white LED, a garnet-based or silicate-based phosphor is used as a yellow phosphor that binds to a blue LED. The yellow-emitting YAG: Ce phosphor, which is a garnet-based phosphor, lacks fluorescence in a red wavelength region and is cold white (cold). white) Emits light. Therefore, the LED of the white light by the conventional garnet-based phosphor has a disadvantage that the color index is low and the color temperature is high. Therefore, there is a demand for the development of phosphors that have better luminous efficiency and excellent luminous characteristics in the red wavelength region than the garnet-based phosphors developed to date. Garnet-based and silicate-based phosphors, which are mainly used for the realization of white light, are limited in meeting these requirements, and there is an urgent need for the development of new phosphors containing a new crystal structure and a phosphor containing active ions. to be.

An object of the present invention is different from the conventional Y ₃ Al ₅ O ₁₂ : Ce, the crystal structure is stable and crystal structure is stable and high fluorescence efficiency, especially in the red wavelength region of the excellent light emission characteristics white LED with high color index and low color temperature To provide a garnet-based (Sm ₃ Al ₅ O ₁₂ : Ce, Gd ₃ Al ₅ O ₁₂ : Ce, Tb ₃ Al ₅ O ₁₂ : Ce, Y ₃ Al ₅ O ₁₂ : Ce) crystal phosphor.

Another object of the present invention is to provide a method for producing a garnet-based yellow crystalline phosphor is simple compared to the manufacturing method of the garnet-based yellow phosphor, the heat loss is low, the process is simple because no separate grinding process.

In order to achieve the above object, in the present invention, a compound represented by the following <Formula 1> has a single crystal structure of a polyhedron, the minimum size of the particles of a single crystal is at least 200nm or more garnet system for white LED It provides a crystalline phosphor.
<Formula 1>
Ln ₃ Al ₅ O ₁₂ : Ce
Where Ln is any one selected from the group of rare earth elements consisting of Sm and Tb

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Here, the fluorescence absorption wavelength of the phosphor is in the 420 ~ 500 nm region, the peak wavelength of the fluorescence absorption is preferably in the range of 430 ~ 495 nm.

In addition, when the phosphor is excited with light of 470 nm, the emission region of fluorescence reaches a wavelength region of 470-700 nm, and the peak of the emission region of fluorescence is preferably in the range of 500-650 nm.

According to another aspect of the present invention, there is provided a white light emitting LED formed by using a crystal phosphor for a white LED having the above characteristics and a blue LED.

According to another aspect of the present invention, a compound represented by the following <Formula 1> has a single crystal structure of a polyhedron, the minimum size of the particles of the single crystal is at least 200nm or more garnet-based crystals for white LED Regarding the manufacturing method of the phosphor,
<Formula 1>
Ln ₃ Al ₅ O ₁₂ : Ce
Where Ln is any one selected from the group of rare earth elements consisting of Sm and Tb
(a) mixing a precursor for uniformly dissolving a precursor of Ln, a precursor of Al, and a precursor of Ce in an alcohol solvent; And
(b) gradually heat-treating the mixed solution in a temperature range of 280 ~ 350 ℃ for more than 24 hours to grow into a polyhedral single crystal having a minimum size of particles of 200nm or more
A method for producing a garnet-based crystalline phosphor for white LED is provided, comprising a.

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Herein, the precursor of Ln is selected from rare earth inorganic salts or rare earth organic salts, the precursor of Al is selected from aluminum alkoxides, and the precursor of Ce is selected from cerium inorganic salts or cerium organic salts.

The garnet polyhedral crystal phosphor of the present invention exhibits a high absorption peak in the blue and green region, and is particularly excellent in fluorescence characteristics than the conventional garnet-based phosphor in the yellow and red wavelength ranges. There is an advantage that it is possible to fabricate a low white light emitting LED.

According to the method of manufacturing a garnet-based crystalline phosphor of the present invention, it is possible to manufacture in a relatively low temperature region compared to the process of manufacturing a garnet-based phosphor, which is superior in energy efficiency, and is produced as a polyhedral crystal phase. There is an advantage that the number of processes is shortened because the grinding process is unnecessary.

Hereinafter, with reference to the accompanying drawings, a garnet-based crystal phosphor for a white LED of the present invention and a manufacturing method thereof will be described in detail.

The yellow phosphor according to the present invention is a garnet-based crystal phosphor represented by the following <Formula 1>.

<Formula 1>

Ln ₃ Al ₅ O ₁₂ : Ce

In the above formula, Ln is a rare earth element such as Gd, Sm, Tb, or Y.

The white light emitting LED is composed of a blue light emitting LED and a phosphor emitting yellow fluorescence. The blue light-emitting LED has a high luminous efficiency and can be used for more than 100,000 hours. Thus, technical problems are almost solved. For the white LED phosphor, in recent years, (i) the efficiency is higher than that of the phosphors developed so far, and (ii) the warm white color is superior to the fluorescence characteristics of the red wavelength region than the garnet-based phosphors so far developed. There is a demand for development of phosphors capable of producing LEDs.

In a conventional YAG-based fluorescent material will be small amount of other rare earth ions as auxiliary agent in optically active ion of Ce ^{3 +} to increase the fluorescence efficiency. Ions added as auxiliaries increase the light absorption efficiency or increase the fluorescence efficiency of Ce ^{3 +} , mainly Tb ^{3 +} , Ga ^{3 +} , Eu ^{2 +} .

In order to make excellent fluorescence properties of the red wavelength region (i) adding the ion (fluorescence adjuvants) which emits fluorescence in the red wavelength region, or, (ii) by replacing the large ion than the Y to Y position Chapter determination of Ce ^{3 +} There is a way to change.

Ions to be added to the adjuvant is a fluorescent deulyimyeo element that emits fluorescent light in a red wavelength region, Pr ^{+ 3,} Cr ^{+ 3,} Dy ^{+ 3,} Eu ^{3 +,} etc. corresponds to this. However, even if the addition of the fluorescent adjuvant has not been reported to the result that the fluorescence characteristics in the red wavelength region is significantly improved.

The energy of Ce ³⁺ ions added to the yag depends on the arrangement of atoms or ions around Ce ³⁺ . This is called the crystal field, and the energy size and separation of ions depend on the distance and symmetry of neighboring atoms. In Yag, eight oxygen atoms are adjacent to Ce ³⁺ , followed by twelve Y atoms. The energy level of Ce ³⁺ ions is directly affected by the charge, size, and symmetry of oxygen atoms and cations such as Y, which are arranged around Ce ³⁺ , and the wavelength of the fluorescence spectrum can be changed by changing the energy level. In the YAG-based yellow phosphor, fluorescence spectra are changed by replacing ions larger than Y ^{3+ with} ions such as Tb ³⁺ , Gd ³⁺ , Sm ³⁺ , La ³⁺ , ... with Y ³⁺ ions. As the amount of substitution of ions increases, the fluorescence wavelength of Ce ³⁺ shifts to the red region. Substitution of a small amount of Tb ³⁺ ions increases the fluorescence efficiency and causes a red shift in the fluorescence wavelength. When the substitution amount of Tb ³⁺ , Sm ³⁺ and Gd ³⁺ exceeds 5% of the total moles, the fluorescence wavelength shifts red but the fluorescence efficiency decreases drastically. Conventional yag-based phosphors having excellent fluorescence characteristics in the red wavelength region utilize red shift of the fluorescence wavelength due to the substitution of cations, and the fluorescence efficiency is lower than that of pure yag-based phosphors. Table 1 shows the size of ions when Y ³⁺ , Tb ³⁺ , Sm ³⁺ , Gd ³⁺ , La ³⁺ and the like are in an environment of coordination number 8. Table 1 is taken from the CRC Handbook of Chemistry and Physics (84th edition).

Table 1.Size of rare earth ions at coordination number 8

ion Y ³⁺ Tb ³⁺ Gd ³⁺ Sm ³⁺ La ³⁺ Radius 1.015 1.04 1.06 1.09 1.18

One of the problems with white LEDs developed to date or solid state lighting using them is cold white with high color temperature and low color index. The warm white white LED that compensates for this is currently using a low-efficiency yellow phosphor to increase the color index, which is due to the failure to develop a fluorescent matrix with excellent color index and fluorescence efficiency.

The temperature for synthesizing Y ₃ Al ₅ O ₁₂ is known to be 1500 ° C. or higher, and the temperature for synthesizing Sm ₃ Al ₅ O ₁₂ and Gd ₃ Al ₅ O ₁₂ may be higher than the temperature for synthesizing Y ₃ Al ₅ O ₁₂ . It has been estimated that no stable synthesis is known. In the present invention, a method of directly growing crystals of Sm ₃ Al ₅ O ₁₂ and Gd ₃ Al ₅ O ₁₂ at a low temperature of 280 ° C. to 350 ° C. was developed by a solvent thermal method. Sm ₃ Al ₅ O ₁₂ and Gd ₃ Al ₅ O ₁₂ added with Ce were yellow phosphors, and their luminescent properties were excellent in Y ₃ Al ₅ O ₁₂ : Ce in the red wavelength region. By applying this, it is possible to manufacture a white LED having a high color index and excellent fluorescence efficiency.

The material of the aluminum garnet (Ln ₃ Al ₅ O ₁₂ ) is composed of a rare earth oxide (Ln ₂ O ₃ ) and alumina (Al ₂ O ₃ ) in a molar ratio of 3: 5 and are currently synthesized at very high temperatures. Since there are 16 rare earth elements (including Sc and Y), 16 kinds of Ln ₃ Al ₅ O ₁₂ may exist chemically, but the presence of large garnets such as La, Ce, Pr, Nd, Pm, and Sm is known. It is known that the larger the radius of ions, the more difficult it is to form a garnet structure.

In Y ₃ Al ₅ O ₁₂ : Ce, which is a representative material of a yellow phosphor for white LEDs, substances such as Gd, Sm, and Tb having large ionic radii are replaced at Y sites in order to shift the fluorescence wavelength red. However, if Gd, Sm, Tb, etc. are substituted, the fluorescence wavelength shifts red, but the fluorescence efficiency decreases, making it difficult to use as a phosphor. Y ₃ Al ₅ O ₁₂ when substituted for Gd, Sm, Tb, etc. in a large amount in, it is estimated that the disorder of the crystal structure Figure (disorder) increases to reduce the activity of ion fluorescence efficiency of Ce ^{+ 3.} Thus, if a radius of the ion can be synthesized garnet consists of a large single element may be red-shift the emission wavelength, will also be missing garnet is structurally stable and fluorescence efficiency reduction of Ce ^{+ 3} consisting of a single element. In the present invention, stable crystals of Y ₃ Al ₅ O ₁₂ , Tb ₃ Al ₅ O ₁₂ , Gd ₃ Al ₅ O ₁₂ , Sm ₃ Al ₅ O _12, and the like were synthesized according to the physical analysis. Was added to implement a yellow phosphor. Among them, Sm ₃ Al ₅ O ₁₂ is a novel substance that has not been reported yet, and a Gd ₃ Al ₅ O ₁₂ yellow phosphor added with Ce is also unknown. The fluorescence spectrum of each material shifted red as expected and there was no decrease in fluorescence efficiency.

The garnet crystal phosphor of the present invention is (i) a new type of phosphor that has not been developed to date. (ii) The existing YAG: Ce phosphor is mainly spherical, but the garnet crystal phosphor of the present invention is in the polyhedral crystal state. (iii) Gd ₃ Al ₅ O ₁₂ : Ce and Sm ₃ Al ₅ O ₁₂ : Ce among the garnet-based crystalline phosphors of the present invention have excellent luminescence properties in the red wavelength region and are well suited for developing a white LED having a high color index. Do.

In the present invention, was to be able to synthesize these garnet phosphors determined by the method of manufacturing the phosphor will be described later, eventually able to provide a polyhedral crystal garnet phosphor was added to Ce ^{+ 3.} Phosphor of the present invention is excellent in fluorescence efficiency compared to the conventional YAG: Ce phosphor, and excellent in the fluorescence characteristics of the red wavelength region. The superiority of the garnet-based crystal phosphor of the present invention will be described later with reference to the drawings.

The process for producing the aluminum garnet-based yellow phosphor of the present invention consists of two processes: (1) precursor mixing and (2) crystal growth. The detailed process is as follows.

(1) mixing process of precursors

In order to manufacture the aluminum garnet-based phosphor of the present invention, a precursor of rare earth element, Al alkoxide and Ce precursor are uniformly dissolved and mixed with alcohol. The molar ratio of the precursor of the rare earth element and the precursor of Al should be 3: 5 = 1: 1.67, which is a chemical quantitative ratio, and the molar ratio of the precursor can be added or subtracted from 3: 4.95 to 3: 5.05 according to the type or amount of the element to be substituted. . When the concentration of the precursor to the solvent is less than 0.05 molar concentration, the synthesized reactant is sufficiently crystallized, and when the concentration of the precursor is greater than 0.05 molar concentration, the uncrystallized reactant remains.

As the precursor used for the production of the aluminum garnet-based yellow phosphor, rare earth organic / inorganic salts such as acetate salts, nitrate salts, acetylacetonate salts and 2 ethyl hexanoate salts of rare earth elements can be used. Precursors including aluminum include aluminum alkoxides that are dissolved or mixed in alcohols such as aluminum methoxide, aluminum ethoxide, aluminum propoxide and aluminum butoxide. The solvent used for the reaction is an organic solvent capable of dissolving alcohols such as methanol, ethanol, 1-propanol, 2-propanol, butanol, 2-methoxyethanol and the aforementioned precursors.

(2) Crystal Growth Process

A solution of a homogeneous mixture of a rare earth element and an aluminum precursor is placed in a high pressure reactor and heated to crystallize. During this reaction, the precursors pyrolyze and grow slowly into crystals by high temperature thermal energy and high pressure mechanical energy. A method of growing crystals at high temperature and high pressure using an organic solution as a solvent is called solvent thermal crystal growth. In the present invention, garnet crystal phosphors were obtained by a solvent thermal method.

The temperature at which the crystal is grown is preferably in the range of 280 ° C to 350 ° C and is heated for at least 24 hours. The temperature and pressure of crystal growth may vary depending on the type of solvent and the amount of solute, and the crystal growth time may also be added or subtracted. The time of crystal growth is related to the yield of grown crystals, but care must be taken when the temperature of the crystal growth is high, the pressure in the high pressure reactor increases rapidly. In addition, at high temperatures, organic solvents pose a risk of oxidation and explosion, so care must be taken. After crystal growth, a precipitate is taken out and the solution is managed separately. Since this precipitate contains reaction wastes and impurities, it is washed with alcohol and water, with dilute acid and dried in air. Aluminum garnet phosphors grown by polyhedral crystals do not require post-heating or reducing processes, but are more efficient than conventional ones. However, it is necessary to relax the state of the synthesized crystals through a separate post-heating and reducing process and reduce the added Ce. It is not to exclude.

By the above steps, the garnet-based crystalline yellow phosphor of the present invention is obtained. In the conventional solid phase reaction method, YAG is synthesized at a temperature of 1500 ° C., but since the synthesis is possible even at a temperature of less than 350 ° C. of the garnet-based crystalline yellow phosphor of the present invention, there is an advantage in that energy required for the synthesis of the phosphor can be saved. In order to increase the fluorescence efficiency of Ce ³⁺ the step of reducing the Ce ^{4 +} generated by the synthesis process must need the conventional YAG: Ce phosphor is a garnet crystal phosphors of the present invention must perform a reduction process at a temperature of 1500 ℃ is Since no additional reduction treatment is required, the energy saving effect is excellent compared to the conventional YAG: Ce manufacturing process.

Conventional YAG: Ce phosphors have a fluorescence spectrum with a peak of 535 nm. The light emission of white LEDs produced by the SMD method using YAG: Ce phosphors and 470 nm blue LEDs is high in color temperature and low in color index. It is called cold white, and in order to overcome this, development of a phosphor having excellent fluorescence in the red wavelength region has been required. Conventional garnet-based phosphors have synthesized phosphors substituted with Gd, Tb, and La in place of Y atoms to increase the fluorescence efficiency of the red region. However, in this method, the fluorescence of the red region is relatively excellent. It has already been described that the efficiency is reduced, resulting in a failure to increase the color index. Conventional YAG forms a very stable crystal phase, so even if the Gd, Tb, La, etc. of different sizes are substituted in the Y atom, the change in the crystal field acting on Ce ^{3 +} ions is insignificant. There is a problem in that the fluorescence of Ce ³⁺ ions due to the substitution of R ⁴ is rather quenched, resulting in a decrease in the overall fluorescence efficiency. However, Sm ₃ Al ₅ O ₁₂ : Ce, Gd ₃ Al ₅ O ₁₂ : Ce, and Tb ₃ Al ₅ O ₁₂ : Ce, which are garnet crystal crystalline phosphors of the present invention, have excellent fluorescence wavelengths.

Figure 1 is a graph showing the x-ray diffraction pattern of the garnet phosphor particles having a polyhedral crystal structure of the present invention, the crystal structure of the four phosphors is a garnet structure of the body center cubic. (a) is Y ₃ Al ₅ O ₁₂ , the lattice constant is 12.00Å, (b) is Gd ₃ Al ₅ O ₁₂ , the lattice constant is 12.12Å, (c) is Tb ₃ Al ₅ O ₁₂ and the lattice constant is 12.09Å , (d) is Sm ₃ Al ₅ O ₁₂ and the lattice constant is 12.10Å. Sm ₃ Al ₅ O ₁₂ is a new garnet-based material of unknown crystal structure. In JCPDS, a similar molecular material (Sm ₂ O ₃ + xAl ₂ O ₃ , JCPDS 29-0080) is reported, but its crystal structure is represented as monoclinic, and Sm ₃ Al ₅ O ₁₂ of the present invention. It is a completely different substance from.

2a to 2c are Y ₃ Al ₅ O ₁₂ according to the present invention measured by an electron microscope The picture of the crystal. (a) is a transmission electron microscope photograph, the scale is 200nm. (b) is the electron diffraction pattern which measured (a) with the transmission electron microscope. It indicates that the individual particles have crystallized. In Figure (b), (222) shows the direction in which the crystal grows. (c) is a photograph measured by SEM. The grown YAG crystal has a size of about 200 nm to about 400 nm.

3a and 3b are graphs of fluorescence excitation and fluorescence spectra of Y ₃ Al ₅ O ₁₂ : Ce crystals according to the present invention. Fluorescence excitation has a peak in the wavelength range of 440nm to 470nm, and the wavelength range of fluorescence excitation is wider than that of conventional Y ₃ Al ₅ O ₁₂ : Ce powder. The peak of the fluorescence spectrum is 535 nm.

4a to 4c are Tb ₃ Al ₅ O ₁₂ according to the present invention measured by an electron microscope The picture of the crystal. (a) is a transmission electron microscope photograph, the scale is 100nm. (b) is the electron diffraction pattern which measured (a) with the transmission electron microscope. The electron diffraction pattern corresponding to the small circle portion of (a) is (b), and the pattern of the electron diffraction corresponding to the large circle is also the same as (b). In other words, (a) shows several different crystals, but one crystal grows like (a). (1-10) in (b) shows the direction of the surface where the tip of the crystal grows sharply. (c) is a photograph measured by SEM and the grown Tb ₃ Al ₅ O ₁₂ crystals have a star-shaped three-dimensional shape. In general, the powder synthesized through the heat treatment (calcine) process is a polyhedron having a sphere shape or face most of the. Since the garnet crystal of the present invention was grown in a solution at a temperature lower than 350 ° C., the garnet crystal was selectively grown in a specific crystal plane direction, and is seen as a three-dimensional star like (c). It can be seen that in the three-dimensional star shape, each growth direction developed perpendicularly to each other.

5a and 5b are Tb ₃ Al ₅ O ₁₂ : Ce according to the present invention Fluorescence excitation and fluorescence spectra of the crystals. Tb ₃ Al ₅ O ₁₂ with Ce The fluorescence of the crystal has a peak at 541.5 nm and is excellent in fluorescence in the red wavelength region as compared with Y ₃ Al ₅ O ₁₂ : Ce, and is a yellow phosphor that can increase the color index of the white LED.

6a to 6c are Gd ₃ Al ₅ O ₁₂ according to the present invention measured by an electron microscope The picture of the crystal. (a) is a transmission electron microscope photograph, the scale is 500nm. (b) is the electron diffraction pattern which measured (a) with the transmission electron microscope. Gd ₃ Al ₅ O ₁₂ It can be seen that the crystal shape is clear as shown in (a). (1-10) in (b) shows the direction of the surface where the tip of the crystal grows sharply. (c) is a photograph measured by SEM and the grown Gd ₃ Al ₅ O ₁₂ crystals have a star-shaped three-dimensional shape.

7a and 7b are Gd ₃ Al ₅ O ₁₂ : Ce according to the present invention Fluorescence of crystals is a graph of the excitation and form spectrum. The peak of fluorescence wavelength is 544.5nm, which is in the red region than the existing Y ₃ Al ₅ O ₁₂ : Ce or Tb ₃ Al ₅ O ₁₂ : Ce, and the fluorescence characteristics of the red wavelength region are superior to the two materials. Gd ₃ Al ₅ O ₁₂ : Ce is a new yellow phosphor that has not been reported to date, and by using this to remove the white LED, the color index of the white LED can be increased and the color temperature can be lowered. In addition, since the temperature for synthesizing Gd ₃ Al ₅ O ₁₂ : Ce is lower than 350 ° C., energy can be saved during the synthesis process. Since the synthesis process is simple and there is no need to reduce Ce, it is possible to economically synthesize a yellow phosphor having a high color index.

8a and 8b are Sm ₃ Al ₅ O ₁₂ according to the present invention measured by an electron microscope The picture of the crystal. (a) is a transmission electron microscope photograph, the scale is 200nm. (b) is a photograph measured by SEM and the grown Sm ₃ Al ₅ O ₁₂ crystal has a three-dimensional shape of a star. Sm ₃ Al ₅ O ₁₂ crystals are new materials that have not yet been reported as described above and are obtained by growing into polyhedral crystals in the present invention.

9a and 9b are Sm ₃ Al ₅ O ₁₂ : Ce according to the present invention. Fluorescence excitation and fluorescence spectra of the crystals. The peak of the fluorescence wavelength is 542.5 nm, and the fluorescence characteristic is excellent in the red wavelength region as compared with the conventional Y ₃ Al ₅ O ₁₂ : Ce, Tb ₃ Al ₅ O ₁₂ : Ce. Sm ₃ Al ₅ O ₁₂ : Ce It is a new yellow phosphor of the novel fluorescent parent developed in the present invention. Sm ₃ Al ₅ O ₁₂ : Warm white white LED can be manufactured by using the fluorescence characteristics of Ce.

10 is a graph comparing the fluorescence spectrum of each of the examples of the garnet-based crystalline yellow phosphor according to the present invention. The maximum intensity of fluorescence was adjusted to be the same, indicating the red shift of the fluorescence spectrum. The wavelengths of the fluorescence peaks are Y ₃ Al ₅ O ₁₂ : Ce is 535 nm, Tb ₃ Al ₅ O ₁₂ : Ce is 541.5 nm, Sm ₃ Al ₅ O ₁₂ : Ce is 542.5 nm, Gd ₃ Al ₅ O ₁₂ : Ce is 544.5 nm. In the red wavelength range of Sm ₃ Al ₅ O ₁₂ : Ce and Gd ₃ Al ₅ O ₁₂ : Ce developed for the first time in the present invention, the fluorescence characteristics of Y ₃ Al ₅ O ₁₂ : Ce and Tb ₃ Al ₅ O ₁₂ : Ce It can be seen that better.

The garnet-based crystal yellow phosphor of the present invention has a high fluorescence efficiency than the conventional garnet-based phosphor in the implementation of a white LED, particularly excellent in the light emission characteristics in the red wavelength region, high color index and low color temperature, the conventional garnet It is possible to replace the fluorescent material, and as a light-emitting means to replace the conventional lighting fixtures, it will be said that it is very widely applicable in all industrial fields including electric, electronic device field and lighting fixtures.

1 is a graph showing an x-ray diffraction pattern of garnet-based phosphor particles having a polyhedral crystal structure of the present invention.

2a to 2c are Y ₃ Al ₅ O ₁₂ according to the present invention measured by an electron microscope Photo of the decision.

Figure 3a and 3b is a graph of the fluorescence excitation and fluorescence spectrum of Y ₃ Al ₅ O ₁₂ : Ce crystal according to the present invention.

4a to 4c are Tb ₃ Al ₅ O ₁₂ according to the present invention measured by an electron microscope Photo of the decision.

5a and 5b are Tb ₃ Al ₅ O ₁₂ : Ce according to the present invention Fluorescence excitation and fluorescence spectrum of the crystal.

6a to 6c are Gd ₃ Al ₅ O ₁₂ according to the present invention measured by an electron microscope Photo of the decision.

7a and 7b are Gd ₃ Al ₅ O ₁₂ : Ce according to the present invention Fluorescence excitation and fluorescence spectrum of the crystal.

8a and 8b are Sm ₃ Al ₅ O ₁₂ according to the present invention measured by an electron microscope Photo of the decision.

9a and 9b are Sm ₃ Al ₅ O ₁₂ : Ce according to the present invention. Fluorescence excitation and fluorescence spectrum of the crystal.

10 is a graph comparing the fluorescence spectrum of each of the examples of the garnet-based crystalline yellow phosphor according to the present invention.

Claims (6)

A compound represented by the following <Formula 1> having a single crystal structure of a polyhedron, the minimum size of the particles of a single crystal is at least 200nm or more, garnet-based crystal phosphor for white LED. <Formula 1> Ln ₃ Al ₅ O ₁₂ : Ce Where Ln is any one selected from the group of rare earth elements consisting of Sm and Tb The method of claim 1, The fluorescence absorption wavelength of the phosphor is in the region of 420 ~ 500 nm, the peak wavelength of fluorescence absorption is 430 ~ 495 nm range, Garnet-based crystal phosphor for white LED. The method of claim 1, When the phosphor is excited with light of 470 nm, the emission region of the fluorescence reaches a wavelength region of 470 to 700 nm, and the peak of the emission region of the fluorescence is within the range of 500 to 650 nm. . A white light emitting LED formed by using a garnet-based crystal phosphor for a white LED selected from any one of claims 1 to 3 and a blue LED. A compound represented by the following <Formula 1> has a single crystal structure of a polyhedron, and relates to a method for producing a garnet-based crystal phosphor for white LED, characterized in that the minimum size of the particles of the single crystal is at least 200nm or more, <Formula 1> Ln ₃ Al ₅ O ₁₂ : Ce Where Ln is any one selected from the group of rare earth elements consisting of Sm and Tb (a) mixing a precursor for uniformly dissolving a precursor of Ln, a precursor of Al, and a precursor of Ce in an alcohol solvent; And (b) gradually heat-treating the mixed solution in a temperature range of 280 ~ 350 ℃ for more than 24 hours to grow into a polyhedral single crystal having a minimum size of particles of 200nm or more Garnet-based crystalline phosphor for white LED, characterized in that comprises a. The method of claim 5, The precursor of Ln is selected from rare earth inorganic salts or rare earth organic salts, The precursor of Al is selected from aluminum alkoxides, The precursor of Ce is selected from the group consisting of cerium inorganic salts and cerium organic salts.

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