KR101673060B1 - Silicon nitride phosphor, method of fabricating the same and light device having the same - Google Patents

Abstract

The present invention relates to a silicon nitride phosphor, a method of manufacturing the same, and an optical device including the phosphor. A silicon nitride phosphor according to an embodiment of the present invention is Ba _ml Eu _l Si ₇ N ₁₀ which is irradiated by an excitation light source to emit light and has a formula of 0.5? M? 2.5 and 0? L? 0.3 Silicon nitride phosphors. The silicon nitride phosphor according to another embodiment of the present invention is Ba _mnl Ca _n Eu _l Si ₇ N ₁₀ , and the silicon nitride phosphor containing a formula of 0.5? M? 2.5, 0 <n? 0.2, 0 < to be.

Description

TECHNICAL FIELD [0001] The present invention relates to a silicon nitride phosphor, a method of manufacturing the same, and an optical device including the silicon nitride phosphor.

The present invention relates to a phosphor mainly composed of a silicon compound, and more particularly, to a silicon nitride phosphor, a method for producing the phosphor, and an optical device including the phosphor.

BACKGROUND ART [0002] Recently, research on an illumination device or an image display device using a solid-state light emitting device such as a semiconductor light emitting diode has been extensively carried out. Among the above lighting devices, a white light emitting diode (LED) is attracting attention as a next-generation high-efficiency lighting device that replaces a conventional incandescent lamp or a fluorescent lamp because electrons and holes combine to emit light. The white LED can be used not only for energy saving based on the efficiency but also for the use of a material having a high environmental load such as mercury and can be installed in a narrow space because the lamp can be downsized, Its application range is long.

A conventional white light emitting diode lamp is composed of a light emitting diode element that emits short wavelength light in the blue region and a phosphor that emits a long wavelength of yellow light by being excited by absorbing a part or all of the light. In this case, the white light is obtained by mixing the blue light generated by the blue light emitting diode and the yellow light generated by the excited phosphor. In the conventional yellow light emitting fluorescent material, there is a garnet fluorescent material consisting of yttrium and aluminum activated by cerium. In this case, white light is obtained by mixing blue light near 450 nm of the blue LED chip and yellow light of about 560 nm of the fluorescent material . However, the white light thus obtained has a wide wavelength interval between blue and yellow, causing color separation, difficulty in mass production of white LEDs having the same color coordinates, difficulty in controlling the color converted temperature, and a high color rendering index CRI) is difficult to obtain.

As another method for obtaining a white LED having an improved color rendering property and a lower color temperature, a method of obtaining white light by exciting blue, green and red phosphors using a near ultraviolet LED of 300 nm to 400 nm can be used. However, since it is difficult to control the color rendering index when only the blue, green, and red phosphors are used, it is possible to obtain a color rendering index of the white LED by combining phosphors of different wavelength ranges using excitation wavelengths in the near ultraviolet region, And color temperature characteristics.

Disclosure of Invention Technical Problem [8] The present invention provides a cyan light emitting phosphor having high efficiency and high emission intensity and excellent temperature stability.

Another technical problem to be solved by the present invention is to provide a method for producing a cyan light-emitting phosphor having the above-mentioned advantages.

Another object of the present invention is to provide various optical elements using the cyan light emitting phosphor having the above-described advantages.

The silicon nitride phosphors according to one embodiment of the present invention for solving the above problems may include a compound represented by the following Chemical Formula 1 that is irradiated by an excitation light source and emits light.

[Chemical Formula 1]

Ba _ml Eu _l Si ₇ N ₁₀ ,

0.5? M? 2.5, and 0.0 < l? 0.3.

The silicon nitride phosphor according to another embodiment for solving the above-mentioned problems may include a compound represented by the following Chemical Formula 2 which is irradiated with an excitation light source and emits light.

(2)

Ba _mnl Ca _n Eu _l Si ₇ N ₁₀ ,

0.5? M? 2.5, 0 <n? 0.2, 0.0 <l? 0.3, mnl> 0.

According to another aspect of the present invention, there is provided a method of manufacturing a silicon nitride phosphor, comprising: mixing a carbonate precursor of Ba, a nitride precursor of Si, and an oxide precursor of an activator Eu; And heat-treating the resultant mixture to form a compound represented by Formula 1.

In another embodiment, a method of making a silicon nitride phosphor comprises the steps of: mixing a carbonate precursor of Ba, a carbonate precursor of Ca, a nitride precursor of Si and an oxide precursor of activator Eu; And heat-treating the resultant mixture to form a compound represented by the following general formula (2).

According to another aspect of the present invention, there is provided an optical device including: an excitation light source that emits light belonging to at least one of a near ultraviolet region, an ultraviolet region, and a blue region; And the silicon nitride phosphor that emits light by being irradiated with the light.

According to the embodiment of the present invention, it is possible to improve the color rendering property of the illumination device by providing the cyan color light of high purity and high brightness using the silicon nitride phosphor, and to provide a cyan cyan) luminescent fluorescent material may be provided.

Further, according to another embodiment of the present invention, a method of manufacturing a cyan light-emitting phosphor having the above-described advantages can be provided.

Further, the red, green, and blue phosphors using the cyan color light source and the near-ultraviolet light source using the cyan light-emitting fluorescent material and the cyan light-emitting phosphor may be mixed to form a white light An optical device using the same can be provided.

1A is a graph showing the ratio of Ba / Si and the theoretical ratio Ba / Si of a sample synthesized according to the mixing ratio of precursor BaCO ₃ in Ba _ml Eu _l Si ₇ N ₁₀ compound according to an embodiment of the present invention .
FIG. 1B is a graph showing the results of X-ray diffraction (XRD) analysis of Ba _ml Eu _l Si ₇ N ₁₀ compound according to the mixing ratio of precursor BaCO ₃ according to an embodiment of the present invention.
2 is a photoluminescence excitation (PLE) spectrum according to Ba ²⁺ composition ratio of Ba _m-0.1 Eu _0.1 Si ₇ N ₁₀ compound according to an embodiment of the present invention.
3 is the dominant peak wavelengths (DPWs) of the photoluminescence (PL) spectrum according to the composition ratio of Ba ²⁺ of the Ba _m-0.1 Eu _0.1 Si ₇ N ₁₀ compound according to the embodiment of the present invention .
4A is a graph showing the thermal quenching of the Ba _0.9 Eu _0.1 Si ₇ N ₁₀ compound according to an embodiment of the present invention in comparison with a green nitride phosphor of (Sr, Ba) -orthosilicate.
FIG. 4B is a graph showing the emission spectrum of Ba _0.9 Eu _0.1 Si ₇ N ₁₀ compound according to an embodiment of the present invention when the composition ratio of Ba ²⁺ is 0.9.
FIG. 5A is a graph illustrating a generalized comparison of luminescence intensities as a result of replacing Ba ²⁺ ions with Ca ²⁺ in a nitride phosphor of Ba _0.9-n Ca _n Eu _0.1 Si ₇ N ₁₀ according to another embodiment of the present invention.
FIG. 5B is a graph showing DPWs as a result of substituting Ca ²⁺ for Ba ²⁺ ions in a nitride phosphor of Ba _0.9-n Ca _n Eu _0.1 Si ₇ N ₁₀ according to another embodiment of the present invention.
FIG. 5c is a graph showing crystal parameters of a nitride phosphor of Ba _0.9-n Ca _n Eu _0.1 Si ₇ N ₁₀ according to another embodiment of the present invention as a result of substituting Ba ²⁺ ions for Ca ²⁺ .
FIG. 6 is a graph showing different emission intensity declines over time versus initial emission intensity of Ba _0.8 Ca _0.1 Eu _0.1 Si ₇ N ₁₀ compound according to an embodiment of the present invention.
7 is a graph showing emission spectra of Ba _0.9-l Ca _0.1 Eu _l Si ₇ N ₁₀ compound according to the composition ratio of Eu ²⁺ according to an embodiment of the present invention.
8 is a cross-sectional view schematically showing a capsule illumination device 100 which is an optical device according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The embodiments of the present invention are described in order to more fully explain the present invention to those skilled in the art, and the following embodiments may be modified in various other forms, The present invention is not limited to the embodiment. Rather, these embodiments are provided so that this disclosure will be more faithful and complete, and will fully convey the scope of the invention to those skilled in the art.

In the following drawings, thickness and size of each layer are exaggerated for convenience and clarity of description, and the same reference numerals denote the same elements in the drawings. As used herein, the term "and / or" includes any and all combinations of any of the listed items.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a," "an," and "the" include singular forms unless the context clearly dictates otherwise. Also, &quot; comprise "and / or" comprising "when used herein should be interpreted as specifying the presence of stated shapes, numbers, steps, operations, elements, elements, and / And does not preclude the presence or addition of one or more other features, integers, operations, elements, elements, and / or groups.

Although the terms first, second, etc. are used herein to describe various elements, components, regions, layers and / or portions, these members, components, regions, layers and / It is obvious that no. These terms are only used to distinguish one member, component, region, layer or section from another region, layer or section. Thus, a first member, component, region, layer or section described below may refer to a second member, component, region, layer or section without departing from the teachings of the present invention.

The present application is related to "Crystal structure and variation of luminescence properties of (Ba, Ca) Si ₇ N ₁₀ " described in 4 (6), 1257 to 1266, published by OPETAL MATERIALS EXPRESS of the present inventor, Quot; Eu ₂₊ as a function of the Eu and Ca concentration &quot;, which is hereby incorporated by reference in its entirety and should be considered part of this specification.

 [Chemical Formula 1]

Ba _ml Eu _l Si ₇ N ₁₀ ,

0.5? M? 2.5 and 0 <l? 0.3.

When m = 1, it may have a stoichiometric composition.

The excitation wavelength band, the absorption intensity, the emission wavelength band, and the emission intensity of the phosphor compound vary depending on the content of Ba ²⁺ and the degree of substitution of Eu ²⁺ in the above formula. The silicon nitride phosphor according to the embodiment of the present invention has a near ultraviolet ray region having a wavelength of 368 nm as an excitation wavelength band within a range where m is in the range of 0.5 to 2.5, And has a cyan color luminescence characteristic with a main emission wavelength of 478 nm. When m is less than 0.5 or more than 2.5, and l is more than 0.3, the peak wavelength of the excitation wavelength band to be absorbed is changed or the absorption efficiency is lowered.

Silicon nitride phosphor according to an embodiment of the present invention, to a substituting a part of Ba ²⁺ to Ca ²⁺ may comprise a compound represented by the formula (2).

 (2)

Ba _mnl Ca _n Eu _l Si ₇ N ₁₀ ,

0.5? M? 2.5, 0 <n? 0.2, 0 <l? 0.3, m-n-1> 0.

When m = 1, it can have a stoichiometric composition.

This wavelength band of the silicon nitride phosphor according to the degree of substitution or the composition ratio of Eu ²⁺ l for the content of Ba ²⁺ and Eu ²⁺ n the degree of substitution of Ca ²⁺ or Ca ²⁺ for Ba ²⁺ in the above formula (2), and The absorption intensity, and the characteristics of the emission wavelength band and the emission intensity are different. When m is less than 0.5 or more than 2.5, and l is more than 0.3, the peak wavelength of the excitation wavelength band to be absorbed may be changed or the absorption efficiency may be lowered. If n is more than 0.2, the degree of deformation of the crystal lattice increases, so that the silicon nitride phosphor may not be excited in the near ultraviolet region and the luminescence sensitivity may be drastically reduced.

The Ba _ml Eu _l Si ₇ N ₁₀ compound and Ba _mnl Ca _n Eu _l Si ₇ N ₁₀ compound according to the embodiment of the present invention can be easily mixed with a solid raw material in a certain ratio and subjected to a heat treatment at a high temperature for a long time . A precursor of Ba, Si, and Eu elements contained in Formula 1 is prepared by the solid phase method. The precursor may be a carbonate, a nitrate, a hydroxide, or a chloride of each element. Preferably, as the precursor, a carbonate of Ba, a nitride of Si, and an oxide of Eu can be used.

For example, the carbonate of Ba may be BaCO ₃ , the nitride of Si may be Si ₃ N ₄ , and the oxide of Eu may be Eu ₂ O ₃ . Si ₃ N _{4, which} is a nitride of Si, is a three-way system α-Si ₃ N ₄ , a hexagonal system β-Si ₃ N ₄ and a cubic system γ-Si ₃ N ₄ , preferably α-Si ₃ N ₄ Can be used. It has been found that when SiO ₂ is used as a precursor of Si to form a matrix of silicon nitride according to an embodiment of the present invention, no stable phase is formed. However, as in the embodiment, when silicon nitride, for example,? -Si ₃ N ₄ is used as a precursor of Si, a stable crystal phase of the silicon nitride phosphor is formed.

The precursors may be provided in powder form, milled through a ball milling process, and mixed together. Preferably, mixing of the precursors can be accomplished by ball milling for 24 hours.

In one embodiment, in order to form a silicon nitride phosphor of Ba _ml Eu _l Si ₇ N ₁₀ of formula (1), the precursors are selected such that the ratio of each precursor mixed, BaCO ₃ : Si ₃ N ₄ : Eu ₂ O ₃ can be mixed so as to satisfy the molar ratio of (xz): 7/3: z. In this case, x may be selected within the range of 0.4 to 1.5, and z may be selected within the range of greater than 0 and 0.3 or less. The removal of z in the mixed molar ratio (xz) of BaCO ₃ is to make it clear that Eu is substituted at the position of Ba.

The above range of x is due to the volatile SiO phase generated when the Ba _m-0.1 Eu _l Si ₇ N ₁₀ compound is produced, so that the amount of barium Ba bonded thereto becomes relatively increased The BaCO ₃ mixing ratio can be selected at 0.4 ≦ x ≦ 1.5 in which the maximum value and the minimum value are reduced from 0.5 ≦ m ≦ 2.5, which is the ratio of the Ba ²⁺ compound according to the embodiment of the present invention. According to the mixing ratio x of BaCO ₃ , the phosphor nitride Ba _ml Eu _l Si ₇ N ₁₀ expressed by the above formula 1 shows the crystal characteristics of BaSi ₇ N ₁₀ , the length and intensity of the excitation wavelength, Strength can vary.

In another embodiment, in order to form a silicon nitride phosphor of Ba _mnl Ca _n Eu _l Si ₇ N ₁₀ of formula (2), the precursors have a ratio of each precursor mixed BaCO _3: CaCO ₃ : Si ₃ N ₄ : Eu ₂ O ₃ can be mixed to satisfy the molar ratio of (xyz): y: 7/3: z. In this case, x may be selected within a range of 0.4 to 1.5, y may be selected within a range of greater than 0 and less than 0.2, and z may be selected within a range of greater than 0 and less than 0.3. Depending on the mixing ratio y of CaCO ₃ , the crystal specification, the excitation wavelength, and / or the length and intensity of the emission wavelength of the _{BaN mnl} Ca _n Eu _l Si ₇ N ₁₀ of the phosphor nitride represented by the above formula (2) may vary. For example, the mixing ratio y of CaCO ₃ may be 0.0 to 0.2, preferably 0.1.

Although metal oxides are generally used in the production of conventional silicon nitride phosphors, in the present invention, an intermediate product is prepared by using the carbonate as a precursor of barium and calcium and the nitride thereof as a precursor of silicon, and thereafter nitriding By forming the silicon nitride phosphor through the process, a fluorescent material having a stable phase can be produced. The heat treatment may be performed in a reducing atmosphere for 30 minutes to 20 hours, for example, a nitrogen atmosphere. The heat treatment may be performed at a temperature of 1,500 ° C to 1,800 ° C, preferably at about 1,600 ° C for about 5 hours in a nitrogen atmosphere. Alternatively, the mixed powder may be heated at a relatively low temperature, for example, 500 [deg.] C, for example, before the sintering process, in order to promote crystal growth while removing impurities such as moisture, organic substances, Lt; 0 &gt; C to 1,000 &lt; 0 &gt; C for 1 hour to 10 hours. The calcining step, and the reducing atmosphere.

The above-described embodiments relate to the solid-phase method, but this is merely illustrative and the present invention is not limited thereto. It will be understood by those skilled in the art that silicon nitride phosphors having the cyan emission characteristics of the present invention can be produced by a known liquid phase method or vapor phase method.

Hereinafter, the excitation strength characteristics and the light emission intensity characteristics at optimum conditions will be described in detail with reference to various analysis results with respect to the characteristics of the phosphor compound according to the composition change of the phosphor compound according to the embodiment of the present invention. The following experimental examples are illustrative only and the present invention should not be limited thereto.

<Experimental Example>

Table 1 below shows experimental conditions of Ba _ml Eu _l Si ₇ N ₁₀ compound according to the embodiment of the present invention. In the measurement samples, the composition ratio m of Ba ²⁺ is selected within the range of 0.5 to 2.5, and the composition ratio l of Eu ²⁺ is selected in the range of greater than 0 and less than 0.3.

Mixture ratio
BaCO ₃ : Si ₃ N ₄ : Eu ₂ O ₃
=
(x-0.1): 7/3: 0.05 The ratio of Ba / Si of the synthesized sample
(± 3%) Of the synthesized sample
Chemical formula Ba _m-0.1 Eu _0.1 Si ₇ N ₁₀ Comparative Example 1-1 x = 0.6 0.08 m = 0.7 Experimental Example 1 x = 0.8 0.13 m = 1.0 Comparative Example 1-2 x = 1.0 0.22 m = 1.6 Comparative Example 1-3 x = 1.2 0.27 m = 2.0

FIG. 1A is a graph showing the ratio of Ba / Si and the theoretical Ba / Si ratio of a sample synthesized according to the mixing ratio of precursor BaCO ₃ in Ba _ml Eu _l Si ₇ N ₁₀ compound according to an embodiment of the present invention And FIG. 1B is a graph showing X-ray diffraction (XRD) analysis results of Ba _ml Eu _l Si ₇ N ₁₀ compound according to the mixing ratio of precursor BaCO ₃ according to an embodiment of the present invention. In addition, the results of X-ray diffraction analysis of BaSi ₇ N ₁₀ (# 89-6751) on a joint committee on power diffraction standards (JCPDS) card were added to FIG.

1A, in an Ba _m-0.1 Eu _0.1 Si ₇ N ₁₀ compound according to an embodiment of the present invention, the experimental mixing ratio (x) of the BaCO ₃ precursor to Si ₇ N ₁₀ and the difference in the theoretical quantitative ratio Is increased as the mixing ratio of the BaCO ₃ precursor increases. The experimental mixing ratio (x) and the theoretical quantitative ratio (m) shown in FIG. 1A are shown in Table 1. (Si) becomes insufficient due to the formation of volatile SiO 2 phase which occurs when a Ba _m-0.1 Eu _0.1 Si ₇ N ₁₀ compound is produced in a furnace and a crucible in a reducing atmosphere, (Ba) is relatively increased. Therefore, as shown in FIG. 1A and Table 1, when the mixing ratio (x) of the BaCO ₃ precursor to Si ₇ N ₁₀ is mixed and synthesized at a ratio lower than the theoretical quantitative ratio of the compound, the compound having the chemical quantitative ratio Can be provided.

When the mixing ratio (x) of the BaCO ₃ precursor is 0.8, the content of nitrogen measured in the Ba _0.9 Eu _0.1 Si ₇ N ₁₀ compound is about 30.5 wt%, which is the theoretical calculated value of 29.5 wt% Can be regarded as the same. From this, it can be confirmed that the mixing ratio (x) of the BaCO ₃ precursor satisfying the chemical quantitation ratio of Ba _0.9 Eu _0.1 Si ₇ N ₁₀ compound is 0.8, which is the experimental mixing ratio, not the theoretical quantitative ratio 0.9. Therefore, through the method for producing the silicon nitride phosphor according to the embodiment of the present invention, a compound having a chemical quantitation ratio can be easily provided.

In the production of the silicon nitride phosphor according to the embodiment of the present invention, the BaCO ₃ precursor produces BaO and CO ₃ while being calcined, and the calculated BaO reacts with carbon (C) to form barium (Ba) and carbon monoxide (CO). In this case, the partial pressures of carbon (C) and carbon monoxide (CO) in the reaction chamber can be controlled. In the reaction chamber, oxygen must be discharged to the outside by carbon monoxide or carbon dioxide, but oxygen is inevitably generated by Eu ₂ O ₃ , and oxygen ions are contained in the lattice of the BaSi ₇ N ₁₀ compound. The amount of Eu ₂ O ₃ is negligible with respect to the starting material.

Referring to FIG. 1B, in Ba _m-0.1 Eu _0.1 Si ₇ N ₁₀ compound according to an embodiment of the present invention, when the BaCO ₃ precursor mixing ratio x is 0.8, 1.0, and 1.2, almost the same diffraction pattern as BaSi ₇ N ₁₀ . &Lt; / RTI &gt; Thus, it can be confirmed that the Ba _m-0.1 Eu _0.1 Si ₇ N ₁₀ compound has the same crystal structure as BaSi ₇ N ₁₀ .

Table 2 shows the results of crystallographic analysis using the Rietveld method of BaSi ₇ N ₁₀ and Ba _0.9 Eu _0.1 Si ₇ N ₁₀ .

Through crystallographic analysis results in Table 2, when the mixing ratio of BaCO ₃ x precursor 0.8 (Experimental Example 1 in Table 1), the same and BaSi ₇ N ₁₀ crystal structure and a space group, and, in place of Ba ²⁺ Eu ²⁺ is completely replaced. In addition, Ba ²⁺ and compare BaSi ₇ N ₁₀ due to the substitution of Eu ²⁺ and _{Ba m-0.1 Eu 0.1 Si 7} N ₁₀ Compound lattice constant, chukgak, volume, minimal changes in the density, so Ba _{0.1 Eu-m It} is confirmed that the crystal structure and space group of the _0.1 Si ₇ N ₁₀ compound are hardly modified.

Component BaSi ₇ N ₁₀ BaSi ₇ N ₁₀ : 0.1 Eu ²⁺ The BaSi ₇ N ₁₀ Ba _0.9 Eu _0.1 Si ₇ N ₁₀ Crystal system monoclinic monoclinic Space group Pc (No. 7) Pc (No. 7) The lattice constant a (A) 6.8729 6.8571 (4) Lattice constant b (A) 6.7129 6.7009 (4) Lattice constant c (A) 9.6328 9.6147 (6) Alpha alpha (DEG) 90 90 Beta β (°) 106.2690 106.248 (4) Gamma &lt; RTI ID = 0.0 &gt; 90 90 Unit cell volume (Å ³ ) 426.63 424.1 Calculated density (g / cm ³ ) 3.69 3.6839 Z 2.0 2.0

2 is a photoluminescence excitation (PLE) spectrum according to Ba ²⁺ composition ratio of Ba _m-0.1 Eu _0.1 Si ₇ N ₁₀ compound according to an embodiment of the present invention. The excitation spectrum was measured in the wavelength range from 250 nm to 430 nm, which is the ultraviolet region from the ultraviolet region.

2, the PLE spectrum of Ba _m-0.1 Eu _0.1 Si ₇ N ₁₀ is 296 nm (C-band), 332 nm (B-band), 363 nm (A- bands of Gaussian sub-bands. The Pel spectrum of the Ba _m-0.1 Eu _0.1 Si ₇ N ₁₀ compound according to the embodiment of the present invention is also composed of three sub-bands. The main wavelength varies depending on the composition ratio of Ba ²⁺ (m-0.1 in Table 1) Mainly A-band or B-band is the dominant wavelength. Particularly, when the composition ratio of Ba ²⁺ according to the embodiment of the present invention is 0.9, the maximum absorption is exhibited with respect to the excitation wavelength of 368 nm, which is high in the range of 280 nm to 330 nm corresponding to the C-band or B- It is a characteristic distinguished from a general BaSi ₇ N ₁₀ : Eu ²⁺ compound having an excitation wavelength. In addition, the absorption amount was increased with respect to the excitation wavelength in the near ultraviolet region including 368 nm in the range of Ba ²⁺ composition ratio of 0.6 to 0.9, that is, in the range of 0.7 to 1 m.

When the composition ratio of barium ions (Ba ²⁺ ) is less than 0.5 or exceeds 2.5, the peak wavelength of the excitation wavelength band absorbed by the silicon nitride phosphor may be changed or the absorption efficiency may be lowered. When the composition ratio of europium ions (Eu ²⁺ ) is more than 0.3, the compositional ratio of BaSi ₇ N ₁₀ ratio extinguishing effect is maximized and the emission wavelength intensity can be drastically reduced.

Since barium ions (Ba ²⁺ ) and substituted europium ions (Eu ²⁺ ) occupy cavities in the network structure of Si ₇ N ₁₀ and their positions are controlled by 13 nitrogen atoms, the 5d level crystals of europium ions Field splitting depends on the amount of nitrogen and oxygen in the crystal. In addition, the conduction band of the BaSi ₇ N ₁₀ compound is determined by the 6s state of barium, while the top valance band is the valence band of the nitrogen atom coordinated by two silicon (Si) atoms. Lt; / RTI &gt; The optical band gap of the experimentally determined BaSi ₇ N ₁₀ compound is about 4 to 4.8 eV. Thus, some or all of the excited energy level of europium ions (i.e., the C-band of about 296 nm, about 4.2 eV) is quite similar to the conduction band of the BaSi ₇ N ₁₀ compound, Means that the energy level scheme of the BaSi ₇ N ₁₀ compound is significantly related to the crystal structure of the BaSi ₇ N ₁₀ compound. Therefore, although the conventional BaSi ₇ N ₁₀ and the Ba _m-0.1 Eu _0.1 Si ₇ N ₁₀ compound according to the embodiment of the present invention have the same diffraction pattern in the XRD results of Fig. 1, the ratio of barium to silicon, Crystal defects, and different PLE spectra from the difference in the ratio of nitrogen and oxygen contained in the crystal.

3 is the dominant-peak wavelengths (DPWs) of the photoluminescence (PL) spectrum according to the composition ratio of Ba ²⁺ of the Ba _m-0.1 Eu _0.1 Si ₇ N ₁₀ compound according to the embodiment of the present invention .

Referring to the experimental conditions shown in FIG. 3 and Table 1, when the emission spectrum was measured for 368 nm excitation light, it had a dominant peak wavelength (DPWs) at 478 nm, center (Eu ²⁺ sites) indicate a singularity. When the composition ratio of Ba ²⁺ is 0.9, it can be confirmed that the light emission intensity is the largest. Accordingly, when the composition ratio of Ba ²⁺ is 0.9, it exhibits the highest excitation intensity at 368 nm and a high emission intensity at a wavelength of 478 nm. However, the characteristic having the main peak wavelength at 478 nm can be maintained within the range of Ba ²⁺ composition ratio of 0.5 to 2.5. A cyan light-emitting silicon nitride phosphor using a wavelength in the near ultraviolet region as a light source is applied to a white LED, so that a white LED or an optical device having excellent color rendering properties can be manufactured.

Figure 4a according to the embodiment of the present invention, Ba _0.9 Eu _0.1 Si ₇ thermal quenching (thermal quenching) of compound N ₁₀ (Sr, Ba) is a graph showing comparison of -orthosilicate hyeonggwangchegwa green oxide, Figure 4b Ba _0.9 Eu _0.1 Si ₇ N ₁₀ compound having a composition ratio of Ba ²⁺ of 0.9 was 0.9, it is a graph showing the emission spectrum according to the temperature change.

4A and 4B, the internal quantum efficiencies (QE) and external quantum efficiencies (QE) of the green oxide are about 107% and 79%, respectively, and BaSi ₇ N ₁₀ : Eu ²⁺ is about The internal QE is excellent, but the external QE must be improved, which can be achieved through manufacturing and post-processing. In this case, the inner QE is the ratio of the number of excited photons absorbed by the phosphor to the number of emitted photons, and the outer QE is the ratio of the number of excited photons irradiated to the phosphor to the number of emitted photons.

The Ba _0.9 Eu _0.1 Si ₇ N ₁₀ exhibits low thermal quenching. For example, the Ba _0.9 Eu _0.1 Si ₇ N ₁₀ gradually decreases in excitation strength at a temperature change from 20 ° C to 180 ° C, but about 80% of the initial strength remains. However, the green nitride rapidly abruptly decreases in strength to about 65% of the initial strength at 180 ° C. Also, the Ba _0.9 Eu _0.1 Si ₇ N ₁₀ shows a difference in the degree of increase of the emission spectrum by about 3.56 nm when the temperature is changed from 20 ° C to 180 ° C (full width at half maximum (FWHM)). Thus, a white LED or an optical device having excellent chromaticity and brightness stability can be manufactured at a temperature of 180 ° C. by using a silicon nitride phosphor of Ba _ml Eu ₁ Si ₇ N ₁₀ .

Table 3 below shows the experimental conditions of the compound of (Ba, Ca) Si ₇ N ₁₀ : Eu ² according to an embodiment of the present invention. In the measurement samples, the composition ratio m of Ba is selected within the range of 0.5 to 2.5, the composition ratio n of Ca is selected within a range of greater than 0 and 0.2 or less, the composition ratio l of Eu is larger than 0, Will be selected within.

BaCO _3: CaCO ₃ : Si ₃ N ₄ : Eu ₂ O ₃
=
(0.7-y): y: 7/3: 0.05 Ba _mln Ca _n Eu _l Si ₇ N ₁₀
(m = 1) Comparative Example 2-1 y = 0 n = 0 l = 0.10 Comparative Example 2-2 y = 0.05 n = 0.05 l = 0.10 Experimental Example 2 y = 0.10 n = 0.10 l = 0.10 Comparative Example 2-3 y = 0.20 n = 0.20 l = 0.10 Comparative Example 3-1 y = 0.1 n = 0.1 l = 0.05 Comparative Example 3-2 y = 0.1 n = 0.1 l = 0.10 Experimental Example 3 y = 0.1 n = 0.1 l = 0.15 Comparative Example 3-3 y = 0.1 n = 0.1 l = 0.20 Comparative Example 3-4 y = 0.1 n = 0.1 l = 0.25

FIG. 5A is a graph illustrating a generalized comparison of luminescence intensities as a result of replacing Ba ²⁺ ions with Ca ²⁺ in a nitride phosphor of Ba _0.9-n Ca _n Eu _0.1 Si ₇ N ₁₀ according to another embodiment of the present invention. FIG. 5B is a graph showing DPWs according to substitution of Ba ²⁺ ions into Ca ²⁺ in a nitride phosphor of Ba _0.9-n Ca _n Eu _0.1 Si ₇ N ₁₀ . FIG. 5C is a graph showing crystal parameters of a nitride phosphor of Ba _0.9-n Ca _n Eu _0.1 Si ₇ N ₁₀ according to substitution of Ba ²⁺ ions into Ca ²⁺ .

Referring to FIG. 5A, in the silicon nitride phosphor of Ba _0.9-n Ca _n Eu _0.1 Si ₇ N ₁₀ , the n value in Table 3 showing the degree of substitution of Ba ²⁺ with Ca ²⁺ or the composition ratio of Ca ²⁺ is 0.05 To about 0.15, the emission intensity of the silicon nitride phosphor is increased by about 120% to 130%. When the value of n, which is a composition ratio of calcium ions (Ca ²⁺ ), is more than 0.2, the luminescence sensitivity of the silicon nitride phosphor is further reduced, and its use as a cyan luminescent phosphor may be limited from a commercial point of view. Further, when Ba ²⁺ is substituted with Ca ²⁺ , the degree of lattice strain of the silicon nitride phosphor increases and it may not be excited in the near ultraviolet region.

Referring to FIG. 5B, when the composition ratio of Ca ²⁺ increases from Ba _0.9-n Ca _n Eu _0.1 Si ₇ N ₁₀ to 0.1, the main peak wavelength is red-shifted from 478 nm to 481 nm, ^When the composition ratio of ²⁺ increases from 0.1 to 0.2, it can be confirmed that the main peak wavelength is shortened from 481 nm to 479 nm. According to the CIE chromaticity coordinates shown in FIG. 5B, when the composition ratio of Ca ²⁺ is larger than 0 and smaller than 0.2 in Ba _0.9-n Ca _n Eu _0.1 Si ₇ N ₁₀ , Ba _0.9-n Ca _n Eu _0.1 Si ₇ N ₁₀ compounds correspond to the cyan color, so that the process stability can be further improved in the production of the cyan light-emitting fluorescent substance.

The diameter of Ca ²⁺ of the silicon nitride phosphor is 1.34 Å, which is smaller than the diameter of Ba ²⁺ of 1.61 Å, and the respective electronegative and ion binding energies are different. Therefore, the Ca ²⁺ ion may be substituted into the site of Ba ²⁺ to cause structural deformation. As can be seen from the above experimental example, the structural modification can modify the length of the main emission wavelength or the emission intensity depending on the composition ratio of Ca ²⁺ in the Ba _0.9-n Ca _n Eu _0.1 Si ₇ N ₁₀ compound .

Referring to FIG. 5C, as the composition ratio of Ca ²⁺ increases from 0 to 0.05, the lattice constants a, b and c hardly change, but the volume of the unit cell increases and the axial angle β . Also, as the composition ratio of Ca ²⁺ increases from 0.05 to 0.2, the lattice constants a, b, and the volume of the unit cell decrease. The lattice constant c and the axis angle? Increase abruptly when the composition ratio of Ca ²⁺ is 0.2, which means that the lattice is deformed when Ba ²⁺ is substituted with Ca ²⁺ . As a result, when the condition that the emission intensity of the silicon nitride phosphor becomes maximum, that is, the composition ratio of Ca ²⁺ is 0.1, the crystal field surrounding Eu ²⁺ is optimized.

The intensity (Dq) of the crystal field is inversely proportional to the fifth power of the coupling length (R) between the central ion (Eu ²⁺ ) and the ligand ion (N ^3- ). That is, it has a relation of Dq? R? ^-5 . Therefore, substitution of barium ions (Ba ²⁺ ) with smaller-sized calcium ions (Ca ²⁺ ) increases the strength of the crystal field, and red-shifting occurs in the Ca ²⁺ composition ratio of 0 to 0.1. Further, when n is the composition ratio of Ca ²⁺ , the blue-shifting occurs, which can be considered as a result of a sudden increase in the lattice constant C and the axis angle?.

FIG. 6 is a graph showing the emission intensity attenuation with time versus the initial emission intensity of Ba _0.8 Ca _0.1 Eu _0.1 Si ₇ N ₁₀ compound according to an embodiment of the present invention.

Referring to FIG. 6, barium vacancies and positive defects generated during the manufacturing process serve as traps for holes or electrons, which may cause delay in luminescence sensitivity decay time have. Therefore, the luminescent sensitivity decay time is related to the crystal structure, lattice defect or nitrogen content of the compound, and particularly, as the lattice defect is smaller, the decay time is reduced. According to an embodiment of the present invention, the I ₀ / e (I ₀ : initial emission intensity at 481 nm) of the Ba _0.8 Ca _0.1 Eu _0.1 Si ₇ N ₁₀ compound is about 0.7 μs. This is equivalent to the typical luminescent sensitivity decay time that occurs because the Eu ²⁺ of the nitride phosphor transitions from the 5d energy level to the 4f energy level and has a single exponential function due to a single activation center. Due to the short luminescence sensitivity decay time of the phosphor according to the embodiment of the present invention, on / off control of the phosphor is easy and can be easily applied to a display.

FIG. 7 is a graph showing the emission spectrum of Ba _0.9-l Ca _0.1 Eu _l Si ₇ N ₁₀ compound according to the composition ratio of Eu ²⁺ , that is, l, according to an embodiment of the present invention.

Referring to FIG. 7, the emission intensity of the Ba _0.9-l Ca _0.1 Eu _l Si ₇ N ₁₀ compound is such that a sufficient luminescence intensity can be obtained at a composition ratio of Eu ²⁺ (l in Table 3) of from 0.05 to 0.2, , The composition is sharply reduced by the composition quenching effect. When the composition ratio of Eu ²⁺ is 0.25, a weak red luminescence is observed at 650 nm in addition to the main luminescence. In the XRD analysis, when the composition ratio 1 of Eu ²⁺ was 0.25, no impurity phase was observed, but red luminescence was observed because the Ba ₂ Si ₅ N ₈ : Eu ²⁺ phase was smaller than the detection limit of XRD . However, the maintenance of the main luminescent property of cyan can be obtained when the composition ratio of Eu &lt; ^{2 +} &gt; is not more than 0.3, and when it is more than 0.3, the main luminescent property can be weakened or vanished in the wavelength range including cyan .

The dominant peak wavelength (DPW) is almost unchanged as the composition ratio of Eu ²⁺ increases. This is because, in the Ba _0.9-l Ca 0 _.1 Eu _l Si ₇ N ₁₀ compound, since the stokes shift, which means a spectral difference between a luminescent band and an absorption band, has a wavelength value of about 6,430 cm ^-1 , And the movement of the luminescent band due to the reabsorption mechanism caused by the overlap of the absorption bands does not occur. With such a characteristic, when silicon nitride according to an embodiment of the present invention is used as a phosphor, the light emitted from the phosphor is minimized to be reabsorbed by the phosphor, so that the energy efficiency of the phosphor can be increased.

8 is a cross-sectional view schematically showing a capsule illumination device 100 which is an optical device according to an embodiment of the present invention.

Referring to FIG. 8, the illumination device 100 includes a light source 10 that emits light and a fluorescent layer 20 that is disposed on the light path of the light source 10 and is excited by light to emit light. The light source 10 may be a semiconductor diode capable of emitting light in the recombination process occurring at the PN junction of the semiconductor. The semiconductor diode may be a UV light emitting diode capable of emitting light in the near ultraviolet region or a blue light emitting diode capable of emitting light in the blue visible light region. The fluorescent layer 20 may include a silicon nitride phosphor having a cyan emission characteristic according to the embodiment of the present invention. The silicon nitride phosphor may be classified and applied so as to have a predetermined particle size distribution in the fluorescent layer 20.

The illumination device 100 may further include leads 11 and 12 for supplying electric power to the light source 10 and wires 13 electrically connecting the leads 12 and the light source 10. The light source 10, the leads 11 and 12 and the wire 13 can be sealed in a shell shape by a suitable sealing material 30 such as translucent resin, rubber and glass.

The bullet-shaped illumination device 100 shown in Fig. 8 is illustrative, and the present invention is not limited thereto. For example, the illumination device may be provided in a known chip type in which an illumination device is formed on a substrate having a recess portion whose top surface is opened. Alternatively, it is also possible to dispose a light source and a fluorescent layer apart from each other, and to transmit the light emitted from the fluorescent layer to a reflector. As another example, it is possible to arrange a fluorescent layer on the sealing material and further seal the fluorescent layer.

The illumination device 100 may be, for example, a white diode lamp. In order to realize the white light, a UV light emitting diode capable of emitting excitation light in a near ultraviolet ray region can be applied. In this case, not only the cyan phosphors but also luminescent phosphors of different colors, for example, red phosphors and blue phosphors may be mixed and used in a predetermined ratio.

The illumination device 100 described above can be used as an illumination device or a display device by itself. Alternatively, the illumination device 100 may be applied to a back light unit of a display device such as a liquid crystal display device, and the present invention is not limited thereto.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. Will be clear to those who have knowledge of.

Claims (28)

delete delete delete delete delete delete A silicon nitride phosphor comprising a compound represented by the following formula (2) which is irradiated by an excitation light source and emits light:
(2)
Ba _mnl Ca _n Eu _l Si ₇ N ₁₀ ,
0.5? M? 2.5, 0 <n? 0.2, 0.0 <l? 0.3, mnl> 0. 8. The method of claim 7,
The silicon nitride phosphor is a cyan luminescent phosphor. 8. The method of claim 7,
Wherein the excitation light source includes a near-ultraviolet region within a range of 360 nm to 380 nm. 9. The method of claim 8,
Wherein the emission peak of the cyan light-emitting fluorescent substance comprises a main emission peak within a range of 460 nm to 490 nm. 8. The method of claim 7,
M is in the range of 0.7 to 1, n is in the range of 0.05 to 0.15, and 1 is in the range of 0.05 to 0.2. 8. The method of claim 7,
M is 1, n is 0.1, and l is 0.1. delete delete delete delete delete delete delete Mixing a carbonate precursor of Ba, a carbonate precursor of Ca, a nitride precursor of Si and an oxide precursor of activator Eu; And
And heat-treating the resultant mixture to form a compound represented by the following formula (2): < EMI ID =
(2)
Ba _mnl Ca _n Eu _l Si ₇ N ₁₀ ,
0.5? M? 2.5, 0 <n? 0.2, 0 <l? 0.3, mnl> 0. 21. The method of claim 20,
Wherein the heat treatment is performed in a nitrogen atmosphere. 21. The method of claim 20,
Wherein the heat treatment is performed at normal pressure. 21. The method of claim 20,
Wherein the heat treatment is performed at a temperature ranging from 1,500 ° C to 1,800 ° C. 21. The method of claim 20,
Wherein the carbonate precursor of Ba comprises BaCO ₃ ,
Wherein the carbonate precursor of Ca comprises CaCO ₃ ,
Wherein the nitride precursor of Si comprises Si ₃ N ₄ ,
Wherein the oxide precursor of Eu comprises Eu ₂ O ₃ . 25. The method of claim 24,
The _{BaCO 3, CaCO 3, Si 3} N 4 , and the ratio of the precursor composition has the formula of Eu ₂ O ₃ is _{BaCO 3: CaCO 3: Si 3} N 4: Eu 2 O 3 = (xyz): y: 7/3 : z, 0.4? x? 1.5, 0 <y? 0.2, and 0 <z? 0.3. 21. The method of claim 20,
Wherein the silicon nitride phosphor has a monoclinic crystal structure. An excitation light source that emits light belonging to at least one of a near ultraviolet ray region, an ultraviolet ray region, and a blue region, and a silicon nitride phosphor according to Claim 7 disposed on the light path of the excitation light source and irradiated by the light to emit light Optical devices. 28. The method of claim 27,
Wherein the optical device is any one of a light emitting device, a lighting device, and a display device.

Images