KR20120063585A - Silicon nitride phosphor, method of fabricating the same and light device - Google Patents

Abstract

PURPOSE: A silicon nitride phosphor, a manufacturing method thereof, and an optical device using thereof are provided to reduce variation of luminous intensity according to temperature and to provide high purity and high brightness red light. CONSTITUTION: A silicon nitride phosphor includes a compound which is represented by following chemical formula 1: Sr_(2-x)A_xSiN_4. The compound is excited by a first light and emits light. In the chemical formula 1, A is an activator which is a combination of more than one or two selected from Ce, Pr, Eu, Tb, Tm, Yb, and Er. X is greater than 0 and less than 2. A manufacturing method of the silicon nitride fluorescent substance comprises the following steps: a step of mixing carbonate precursor of metal M, nitride precursor of Si, and oxide precursor of an activator A; and a step of forming the silicon nitride fluorescent substance by sintering the mixed outcome.

Description

Silicon nitride phosphor, method for manufacturing same, and optical device using the same {Silicon nitride phosphor, method of fabricating the same and light device}

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 same, and an optical device using the same.

Recently, researches on lighting devices or image display devices using solid state light emitting devices such as semiconductor light emitting diodes have been widely conducted. Among the lighting devices, the white light emitting diode lamp is attracting attention as a next-generation high efficiency lighting device replacing a conventional incandescent light bulb or a fluorescent lamp. The white light emitting diode lamp can exclude the use of a material having a high environmental burden such as mercury as well as an energy saving effect due to its efficiency.

A conventional white light emitting diode lamp is composed of a light emitting diode element that generates short wavelength light in a blue region and a phosphor that absorbs some or all of the light to emit long wavelength yellow light. In this case, the white light is obtained by mixing the blue light emitted by the blue light emitting diode and the yellow light generated by the excited phosphor. Conventional yellow light emitting phosphors include garnet-based phosphors composed of yttrium and aluminum activated with cerium. However, the white light obtained through them lacks a red component, making it difficult to improve the color rendering of illumination. In addition, due to the lack of a red component, there is a problem that it is difficult to obtain a white lighting device having a low color temperature similar to that of a light bulb using only a conventional yellow light emitting phosphor.

As described above, in order to improve the color rendering and obtain a lighting device having a low color temperature, a small amount of red phosphor may be mixed with the yellow phosphor, or a green phosphor and a red phosphor may be used instead of the yellow phosphor. In this case, development of a red light emitting phosphor having excellent color purity is required. In addition, in order to ensure long life and high power in optical devices such as lighting devices and display devices, the red light-emitting phosphor to be applied thereto needs to have excellent temperature stability.

The technical problem to be solved by the present invention is to provide a silicon nitride-based phosphor having a novel composition and small change in the emission intensity with temperature, which can be applied to high power optical devices.

In addition, another technical problem to be solved by the present invention is to provide a red light emitting phosphor capable of providing high purity and high luminance red light to improve color rendering as a silicon nitride phosphor.

Another technical problem to be solved by the present invention is to provide a manufacturing method capable of economically manufacturing a silicon nitride phosphor having the aforementioned advantages.

In addition, another technical problem to be solved by the present invention is to provide various optical devices to which the silicon nitride phosphor having the above-described advantages is applied.

Silicon nitride phosphor according to an embodiment of the present invention for achieving the above technical problem is a silicon nitride phosphor comprising a compound having the formula (1) to be excited by the first light to emit light.

[Formula 1]

Sr _{2 - x} A _x SiN ₄

A is an active agent of any one or two or more combinations selected from the group consisting of Ce, Pr, Eu, Tb, Tm, Yb and Er, and 0 <x <2.

In some embodiments, A can be Eu. In this case, the silicon nitride phosphor may be a red light emitting phosphor. In addition, the emission peak of the red light-emitting phosphor may include an emission peak of 623nm. In addition, the first light may have a wavelength belonging to any one of a near ultraviolet band and a blue light band and a combination thereof.

Silicon nitride phosphor according to another embodiment of the present invention may include a compound having the formula (2) to be excited by the first light to emit light.

[Formula 2]

M _{2 - x} A _x SiN ₄

M is any one or a combination of two or more selected from the group consisting of Sr, Ca, Ba and Mg, and A is any one or two selected from the group consisting of Ce, Pr, Eu, Tb, Tm, Yb and Er It is an active agent of the above combination, and can be 0 <x <2. The silicon nitride phosphor may be deoxygenated.

According to another aspect of the present invention, there is provided a method of manufacturing a silicon nitride phosphor, including: mixing a carbonate precursor of metal M, a nitride precursor of Si, and an oxide precursor of activator A; And sintering the mixed result to form a compound of Formula 1 below.

(3)

M _{2 - x} A _x SiN ₄

M is any one or a combination of two or more selected from the group consisting of Sr, Ca, Ba and Mg, and A is any one or two selected from the group consisting of Ce, Pr, Eu, Tb, Tm, Yb and Er It is an active agent of the above combination, and can be 0 <x <2.

In some embodiments, the sintering can be performed in a nitrogen atmosphere. In addition, the sintering may be performed at 1700 ℃ to 1800 ℃.

In some embodiments, the carbonate precursor of Sr comprises SrCO ₃ , the nitride precursor of Si comprises Si ₃ N ₄ , and the oxide precursor of Eu comprises Eu ₂ O ₃ .

According to another aspect of the present invention, there is provided an optical device including a light source emitting light belonging to at least one of a near ultraviolet region and a blue region, and disposed on an optical path of the light source. It may include the above-described phosphor compound which is excited by and emits light. The optical device may be an illumination device or a display device.

The silicon nitride phosphor according to the embodiment of the present invention has a small emission quenching with temperature due to strong covalent bonding of silicon nitride crystals. In addition, the nitride phosphor has a wide excitation wavelength range over the near ultraviolet region and the blue visible region because of the characteristic covalent bonding between the N ligand and the activator such as Eu2 +, and has high luminous efficiency. From such a small change in luminous intensity and high luminous efficiency, a phosphor applicable to a high output optical device can be provided.

In addition, the silicon nitride phosphor according to the embodiment of the present invention exhibits light emission characteristics having a center wavelength of greater than 620 nm by appropriately selecting the metal element of the crystal host and the active element doped thereto, thereby improving color rendering properties and improving efficiency. And a phosphor having high luminance emission characteristics.

In addition, according to the method of manufacturing a red light-emitting phosphor according to an embodiment of the present invention, the above-mentioned silicon nitride phosphor can be economically produced by a solid phase method.

In addition, the optical device according to the embodiment of the present invention, by using a red light emitting phosphor having a center wavelength in the 623 nm region can realize a low color temperature in the case of white illumination as well as improve the color rendering. In addition, the red light-emitting phosphor of the present invention has a low temperature dependency, and by using the same, an optical device having a long lifetime and high output can be provided.

1 is a graph showing the results of X-ray diffraction analysis of β-Sr ₂ SiN ₄ and α′-Sr ₂ SiN ₄ according to Example 1 of the present invention.
2 is a photoluminescence excitation (PLE) spectrum of β-Sr ₂ SiN ₄ : Eu and α′-Sr ₂ SiN ₄ : Eu according to Example 1 of the present invention.
3A to 3C are emission spectra of samples excited by electromagnetic waves having wavelengths of 320 nm, 377 nm and 466 nm, respectively.
4 is a graph illustrating thermal quenching characteristics of β-Sr ₂ SiN ₄ : Eu according to an embodiment of the present invention.
5 is a cross-sectional view schematically showing an encapsulated lighting element that is an optical device according to an embodiment of the present invention.

Hereinafter, exemplary 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 into various other forms, It is not limited to the embodiment. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the inventive concept to those skilled in the art.

In addition, in the following drawings, the thickness or size of each layer is exaggerated for convenience and clarity of description, the same reference numerals in the drawings refer to the same elements. As used herein, the term “and / or” includes any and all combinations of one or more 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" may include the plural forms as well, unless the context clearly indicates otherwise. Also, as used herein, "comprise" and / or "comprising" specifies the presence of the mentioned shapes, numbers, steps, actions, members, elements and / or groups of these. It is not intended to exclude the presence or the addition of one or more other shapes, numbers, acts, members, elements and / or groups.

Although the terms first, second, etc. are used herein to describe various members, parts, regions, layers, and / or parts, these members, parts, regions, layers, and / or parts are defined by these terms. It is obvious that not. These terms are only used to distinguish one member, part, region, layer or portion from another region, layer or portion. Thus, the first member, part, region, layer or portion, which will be discussed below, may refer to the second member, component, region, layer or portion without departing from the teachings of the present invention.

The red light-emitting phosphor of the present invention includes a compound represented by the following formula (1).

[Formula 1]

Sr _{2 - x} A _x SiN ₄

A is an active agent of any one or two or more combinations selected from the group consisting of Ce, Pr, Eu, Tb, Tm, Yb, and Er doped with a parent Sr ₂ SiN ₄ , preferably, the active agent is Eu to be. In addition, 0 <x <2. In the present specification, the formula Sr _{2 -x} A _x SiN ₄ is used interchangeably with Sr ₂ SiN ₄ : Eu, which is another expression generally used in the art.

The phosphor compound according to another embodiment of the present invention may include a compound represented by the following Chemical Formula 2 in which part or all of Sr of the above-described phosphor compound is substituted with an alkali metal, that is, Ca, Ba, or Mg.

[Formula 2]

M _{2 - x} A _x SiN ₄

M is any one or a combination of two or more selected from the group consisting of Sr, Ca, Ba and Mg, and A is any one or two selected from the group consisting of Ce, Pr, Eu, Tb, Tm, Yb and Er The active agent may be a combination of any of the above, and preferably, the active agent is Eu. In addition, 0 <x <2. In this specification, the formula M _{2 - x} A _x SiN ₄ is another expression of M ₂ SiN ₄ is generally used in the art, used as Eu and interchangeably.

Hereinafter, the features and advantages of the present invention will be described with reference to the analysis results for the samples prepared according to the embodiments of the present invention. However, the following examples are only illustrative and are not intended to limit the present invention.

Example  One: Sr ₂ SiN ₄ : Eu Manufacture

The silicon nitride phosphor Sr ₂ SiN ₄ : Eu according to the embodiment of the present invention can be easily produced by the solid phase method. In order to manufacture the silicon nitride phosphor by the solid phase method, a precursor of each element included in Chemical Formula 1 is prepared. The precursor may be an oxide, carbonate, nitrate, hydroxide and chloride of each element. Preferably, the precursor may be a carbonate of Sr, a nitride of Si and an oxide of Eu. For example, the carbonate of Sr may be SrCO ₃ , the nitride of Si may be Si ₃ N ₄ , and the oxide of Eu may be Eu ₂ O ₃ . The precursors may be provided in powder form, and the mixing ratio of these powders may be selected such that N is 4 mol when the addition amount of Si, which is a central element, is fixed at 1 mol.

Although metal nitrides have generally been used in the manufacture of conventional phosphor nitrides, in the present invention, intermediate phosphor compounds are prepared using metal carbonates and metal oxides, and then silicon nitride phosphors are manufactured through a deoxygenation process. In general, in the case of metal nitride, the raw material is expensive, raw material properties are not stable, and the manufacturing process is complicated. However, according to the embodiment of the present invention, since metal carbonate or metal oxide is used as a precursor in place of metal nitride, not only the manufacturing cost is reduced but also the stable raw material property allows manufacturing by a simple process. In addition, since the oxide is used, the synthesis process of the phosphor at atmospheric pressure can be performed.

Sr ₂ SiN ₄ can be activated by divalent Eu ions. Eu may be doped by substituting Sr, and the amount of Eu added to 1 mol of Si may be 0.0001 mol to 0.5 mol, and preferably 0.01 mol to 0.2 mol. When the amount of Eu added is less than 0.0001 mol, photoelectric transfer is not easy, and when the amount of Eu is 0.5 mol or more, the luminance may be lowered due to the concentration quenching phenomenon. In addition, the intensity of the peak can be adjusted by adjusting the ratio of Sr and Eu.

Once the mixed powder has been prepared in a suitable proportion, it is sintered at about 1700 ° C. to 1800 ° C., preferably at 1750 ° C. for 1 to 20 hours. The sintering process may be performed in a reducing atmosphere, for example N ₂ atmosphere, to be completely deoxygenated. In addition, the sintering process may be performed at normal pressure. Optionally, in order to promote crystal growth while removing impurities such as complexes of water, organics or some salts contained in the mixed powder, a relatively low temperature, e. The firing process may be performed at 1 ° C. to 1000 ° C. for 1 to 10 hours. The firing process may also be carried out in a reducing atmosphere.

The sintered body obtained in the sintering process may be pulverized into powder form and subjected to a washing process as necessary. Thus, the obtained red light emitting phosphor Sr ₂ SiN ₄ : Eu may have a crystal structure of β or α phase, as described later with reference to FIG. 1.

Example  2: M ₂ SiN ₄ Manufacture of A

Example 1 described above relates to Sr ₂ SiN ₄ : Eu, but with, or in place of, all of the precursors of other alkali metals, for example any of the precursors of Ca, Ba and Mg or Using these combinations, the formula M ₂ SiN ₄ : A (wherein M is one or two or more combinations selected from the group consisting of Sr, Ca, Ba and Mg, wherein A is Ce, Pr, Eu, Tb, Tm, Red luminescent phosphors having one or two or more combinations of activators selected from the group consisting of Yb and Er.

Precursors of the elements included in the chemical formula may be oxides, carbonates, nitrates, hydroxides and chlorides of each element. For example, as the precursors of the respective elements, the carbonate of M, the nitride of Si and the oxide of Eu may be used.

The precursors may be provided in powder form, and the mixing ratio of these powders may be selected such that N is 4 mol when the addition amount of Si, which is a central element, is fixed at 1 mol. In addition, these precursors may be provided in powder form, and the mixing ratio of these powders may be selected such that N is 4 mol when the addition amount of Si, which is a central element, is fixed at 1 mol.

The phosphor compound according to Example 2 may be prepared through the sintering process described in Example 1 and optionally, a sintering process before sintering. In addition, the sintering process and / or the firing process may be performed at normal pressure.

Although the above-described embodiments relate to the solid state method, this is exemplary and the present invention is not limited thereto. Those skilled in the art will appreciate that the red light emitting phosphor of the present invention can be produced by known liquid phase or vapor phase methods.

Comparative example  One: Sr ₂ SiO ₄ : Eu Manufacture

For the characterization of the red light emitting phosphor, which is a nitride phosphor according to an embodiment of the present invention, Sr ₂ SiO ₄ : Eu phosphor (Comparative Example 1), which is a silicate-based phosphor having 4 mol of O relative to the center element Si, was used as a comparative sample. It prepared by the solid state method.

Comparative example  2: Sr ₂ Si ( ON ) ₄ : Eu Manufacture

For the characterization of the red light emitting phosphor, which is a nitride phosphor according to an embodiment of the present invention, as another comparative sample, Sr ₂ Si (ON) ₄ : Eu phosphor, an oxynitride-based phosphor in which a portion of N is substituted with O (Comparative Example) 2) was prepared by the solid phase method.

1 is a graph showing the results of X-ray diffraction analysis of β-Sr ₂ SiN ₄ (curve L1) and α′-Sr ₂ SiN ₄ (curve L2) according to Example 1 of the present invention. In FIG. 1, the curves R1 and R2 compared to the curves L1 and L2 are the values of α′-Sr ₂ SiO ₄ of Comparative Example 1 and (α ′ + β) -Sr ₂ Si (ON) ₄ : Eu of Comparative Example 2, respectively. X-ray diffraction analysis results are shown. In addition, Fig. 1 shows the results of X-ray diffraction analysis of β-Sr ₂ SiO ₄ (# 38-0271) and α'-Sr ₂ SiO ₄ (# 39-1256) on a Joint Committee on Power Diffraction Standards (JCPDS) card. Added.

Referring to FIG. 1, β-Sr ₂ SiN ₄ (curve L1) and α＇-Sr ₂ SiN ₄ (curve L2) of a single phase according to an embodiment of the present invention, respectively, β-Sr ₂ SiO ₄ (# 38) on a JCPDS card. -0271) and α'-Sr ₂ SiO ₄ (# 39-1256). Therefore, β-Sr ₂ SiN ₄ and α'-Sr ₂ SiN ₄ according to Example 1 are expected to have the same crystal structures as β-Sr ₂ SiO ₄ and α'-Sr ₂ SiO ₄ , respectively, which are silicate-based phosphors. .

In FIG. 1, referring to the curve R1, it can be seen that the manufactured Sr ₂ SiO ₄ : Eu (Comparative Example 1) has an α ′ phase from the pattern on the JSPDS. Similarly, referring to the curve R2, it can be seen that the α 'phase and the β phase coexist in the manufactured Sr ₂ Si (ON) ₄ : Eu (Comparative Example 2).

The nitride phosphor according to Example 1 has the same crystal structure as that of the silicate phosphor of Comparative Example 1, but the nitride phosphor according to Example 1 has a luminescent property that is remarkably distinguished from the light emitting characteristics of the silicate phosphor as described below. Has Below, the optical characteristic with respect to the sample of Examples 1 and 2 and Comparative Examples 1 and 2 is disclosed.

2 is a photoluminescence excitation (PLE) spectrum of β-Sr ₂ SiN ₄ : Eu (curve L1) and α′-Sr ₂ SiN ₄ : Eu (curve L2) according to Example 1 of the present invention. In FIG. 2, curves R1 and R2 are excitation spectra of α′-Sr ₂ SiO ₄ : Eu of Comparative Example 1 and Sr ₂ Si (ON) ₄ : Eu of Comparative Example 2, respectively. These excitation spectra were measured in the wavelength range between 200 nm and 500 nm in the ultraviolet region.

Referring to FIG. 2, in the case of the red light-emitting phosphor according to Example 1, β-Sr ₂ SiN ₄ : Eu (curve L1) and α′-Sr ₂ SiN ₄ : Eu (curve L2), as well as the near ultraviolet region, In the short wavelength visible light region (blue visible light region), the excitation intensity gradually increases toward the longer wavelength. It was also observed that the Sr ₂ SiN ₄ : Eu (curve L1) on β had a somewhat higher intensity than the Sr ₂ SiN ₄ : Eu (curve L2) on α '.

Recently, InGaN-based diodes capable of high luminance emission in the near ultraviolet region and the short wavelength visible light region have attracted attention. In the case of β-Sr ₂ SiN ₄ : Eu and α'-Sr ₂ SiN ₄ : Eu according to the embodiment of the present invention, since it has high absorption intensity not only in the near ultraviolet region but also in the short wavelength visible region, it has high efficiency. It is expected that an optical device capable of high luminance light emission can be obtained.

Referring to the spectrum (curve R1) of α'-Sr ₂ SiO ₄ : Eu of Comparative Example 1, peaks are generated at 322 nm and 377 nm, respectively. The peak at 320 nm is due to the Sr (I) site and 377 nm is due to the Sr (II) site. The curve R1, unlike the curves L1 and L2, rapidly decreases the excitation intensity toward the long wavelength near 370 nm. This is predicted because the wavelength corresponding to the excitation energy of the electron pair of α'-Sr ₂ SiO ₄ : Eu is in the ultraviolet region. Thus, Comparative Example 1 of the α'-Sr ₂ SiO _4: absorption intensity of Eu (curve R1) is, and is rapidly decreased in accordance with the above 400 nm, the wavelength becomes longer.

Referring to the spectrum (curve R2) of Sr ₂ Si (ON) ₄ : Eu, which is an oxynitride-based phosphor of Comparative Example 2, it can be confirmed that even after 370 nm, the excitation intensity does not decrease and has a flat form. However, in the case of Sr ₂ Si (ON) ₄ : Eu (curve R2) of Comparative Example 2, the excitation strengths are β-Sr ₂ SiN ₄ : Eu (curve L1) and α′-Sr ₂ SiN ₄ : Eu (curve L2 Significantly less than 50%).

3A to 3C are emission spectra of samples excited by electromagnetic waves having wavelengths of 320 nm, 377 nm and 466 nm, respectively.

Referring to FIG. 3A, the red phosphor, β-Sr ₂ SiN ₄ : Eu (curve L1) according to Example 1, has a spectrum having a single peak at 623 nm upon excitation by light having a wavelength of 320 nm. Similarly, a peak is observed only at 623 nm in α'-Sr ₂ SiN ₄ : Eu (curve L2). In the conventional LDE lighting element, in order to improve the color rendering index of white light, it is known that it is most effective when the emission wavelength of the red light emitting phosphor becomes 620 nm to 630 nm. According to the embodiment of the present invention, since the emission wavelength is 623 nm, excellent color purity can be ensured.

In the case of α'-Sr ₂ SiO ₄ : Eu (curve R1) according to Comparative Example 1, no peak is observed at 623 nm, and only a peak is observed at 477 nm and 534 nm, which are yellow visible light regions. Of these peaks, the peak at 477 nm is due to the Sr (I) site and the peak at 534 nm is the emission wavelength due to the Sr (II) site. Although the silicate compounds of β-Sr ₂ SiN ₄ : Eu (curve L1) and α'-Sr ₂ SiN ₄ : Eu (curve L2), which are red light emitting phosphors according to an embodiment of the present invention, have the same crystal structure, It should be noted that the red light emitting phosphor does not have characteristic peaks of 477 nm and 534 nm appearing in the silicate phosphor, and the silicate phosphor does not have a characteristic peak of 623 nm that the red light emitting phosphor has.

In the case of the oxynitride-based phosphor Sr ₂ Si (ON) ₄ : Eu (curve R2) of Comparative Example 2 having a structure in which nitrogen was partially substituted with oxygen, an emission peak was observed at a wavelength of 477 nm by Sr (I). The luminescence peak by Sr (II) is observed at a wavelength of 605 nm. From the spectrum of the comparative example 2 (curve R2), it can be seen that when a part of nitrogen is replaced with oxygen, a spectrum having a characteristic 623 nm center wavelength of the phosphor according to the embodiment of the present invention cannot be obtained.

Referring to FIG. 3B, the β-Sr ₂ SiN ₄ : Eu (curve L1) and α′-Sr ₂ SiN ₄ : Eu (curve L2) of Example 1 were both single peaks of 623 nm, even at an excitation wavelength of 377 nm. It has a light emission characteristic having. Likewise, no peaks appear at 477 nm and 534 nm.

In contrast, for α′-Sr ₂ SiO ₄ : Eu (curve R1) of Comparative Example 1, the peak at 477 nm by the Sr (I) site and the emission peak at 534 nm by the Sr (II) site are still present. appear. Compared with the excitation wavelength characteristic of 320 nm shown in FIG. 3A, it can be seen that α′-Sr ₂ SiO ₄ : Eu (curve R1) has a larger emission intensity at a wavelength of 533 nm than an emission intensity of 477 nm. In the case of the oxygen nitride phosphor Sr ₂ Si (ON) ₄ : Eu (curve R2) of Comparative Example 2, the intensity of the emission wavelength of 477 nm by Sr (I) is decreased, and the emission wavelength by Sr (II) is It is observed relatively strongly at 605 nm. However, the luminescence intensity of 605 nm is smaller than that of Example 1.

Referring to FIG. 3C, for the red phosphors β-Sr ₂ SiN ₄ : Eu (curve L1) and α′-Sr ₂ SiN ₄ : Eu (curve L2) according to Example 1, still at an excitation wavelength of 466 nm A single peak of 623 nm was observed. In the case of α'-Sr ₂ SiO ₄ : Eu (curve R1) of Comparative Example 1, the peak at 477 nm due to the Sr (I) site disappears, and only the emission wavelength due to the Sr (II) site is shifted to 540 nm. appear. In the case of the oxygen nitride phosphor Sr ₂ Si (ON) ₄ : Eu (curve R2) of Comparative Example 2, the emission wavelength of 477 nm by Sr (I) disappears, and the emission wavelength by Sr (II) is 605 nm. It was moved to and observed.

3A to 3C, it can be seen that in the case of the oxynitride-based fluorescent material, when the wavelength of the excitation electromagnetic wave is increased from the ultraviolet region to the blue region, the light emission characteristics of the long wavelength can be obtained. However, the emission wavelength of the oxynitride-based phosphor is still present in the yellow visible light region of 620 nm or less, compared with the red luminescent phosphor according to the embodiment of the present invention, the emission intensity of the oxynitride-based phosphor at 620 nm or more Is less than 50%.

3A to 3C, β-Sr ₂ SiN ₄ : Eu and α′-Sr ₂ SiN ₄ : Eu, which are red phosphors according to the exemplary embodiment of the present invention, are near-ultraviolet region belonging to 320 nm and 377 nm, and 450 nm. And the excitation light in the blue visible light region to which 466 nm belongs, all have an emission center wavelength at 623 nm, and high emission intensity of 90% or more can be obtained in the 620 nm and 630 nm regions.

Therefore, the silicon nitride phosphor according to the embodiment of the present invention is capable of high purity red light emission, thereby improving color rendering and providing a white lighting device having a low color temperature. In addition, the silicon nitride phosphor according to the embodiment of the present invention has higher emission intensity as compared with Sr ₂ Si (ON) ₄ : Eu, which is an oxynitride-based phosphor, so that the luminance can be improved along with the color purity. There is an advantage.

In general, a solid phase method in which a phosphor is mixed with a predetermined ratio of solid phase raw materials and subjected to a long heat treatment at a high temperature is used. In the solid phase method, fluxes such as alkali chlorides and alkali fluorides are used to obtain pure single-phase phosphors in which unreacted or additional secondary phases do not exist. Β-Sr ₂ SiN ₄ : Eu and α′-Sr ₂ SiN ₄ : Eu, which are red light emitting phosphors according to an embodiment of the present invention, are the same, although the crystal phases are different from each other, as shown in FIGS. 3A to 3C. Since it has light emission characteristics with a center wavelength of 623 nm, the process burden for obtaining a single phase can be reduced or eliminated during the production of these phosphors.

In FIGS. 3A to 3C, Sr ₂ SiN ₄ : Eu is related, but M ₂ SiN ₄ : Eu, which is a silicon nitride phosphor in which at least one of Ca, Ba, and Mg is substituted instead or with Sr, has the same crystallinity. Due to this, it may have a red light emitting property of high purity and high brightness.

4 is a graph illustrating thermal quenching characteristics of β-Sr ₂ SiN ₄ : Eu according to an embodiment of the present invention. The wavelength of the excitation electromagnetic wave was 450 nm, and the intensity change of the light emission wavelength having a wavelength of 623 nm was measured while increasing the temperature from room temperature to 150 ° C.

Referring to FIG. 4, the intensity change of the emission wavelength was less than 10% while the temperature was raised to 150 ° C. based on room temperature (reference value = 1). The measured CIE (Commission International de I 'Eclarge) color coordinate is (0.6433, 0.3510). From the results of FIG. 4, it can be seen that the silicon nitride phosphor according to the embodiment of the present invention is suitable for a high output optical device.

5 is a cross-sectional view schematically showing an encapsulated lighting element that is an optical device according to an embodiment of the present invention.

Referring to FIG. 5, the lighting device 100 includes a light source 10 emitting light and a fluorescent layer 20 disposed on an optical path of the light source 10 and excited from the light to emit light. The light source 10 may be a semiconductor diode capable of emitting light during a 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 region. The fluorescent layer 20 may include a red light emitting phosphor according to the embodiment of the present invention described above. The red light-emitting phosphor may be classified and applied to have a predetermined particle size distribution in the phosphor layer 20.

The lighting device 100 may further include leads 11 and 12 for supplying 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, 12 and the wire 13 may be sealed in shell form by a suitable sealant 30 such as translucent resin, rubber and glass.

The shell type lighting element 100 shown in FIG. 5 is exemplary, and the present invention is not limited thereto. For example, the lighting element can be provided in the form of a known chip in which the lighting element is formed on a substrate having a recessed portion with an open top. Alternatively, a reflective lighting device may be disposed to be spaced apart from the light source and to transmit the light emitted from the fluorescent layer to the reflecting plate. As another example, it is also possible to arrange the fluorescent layer on the sealing material and further seal the fluorescent layer.

The lighting device 100 may be, for example, a white diode lamp. As the white light, a part of the light emitted from the light source 10 and the wavelength-converted light emitted by the red light-emitting phosphor excited in the fluorescent layer 20 may be mixed to implement white color. Optionally, a green light emitting phosphor may be further included in the fluorescent layer 20 together with the red light emitting phosphor. In order to implement white light, the light source 10 may be a blue light emitting diode. The blue light emitting diode may be, for example, an InGaN based diode.

As another configuration for realizing the white light, a UV light emitting diode capable of emitting excitation light in the near ultraviolet region may be applied. In this case, as the visible light emitter, not only red phosphor but also light emitting phosphors of different colors, for example, green phosphor and blue phosphor may be mixed and used in a predetermined ratio.

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

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and alterations are possible within the scope without departing from the technical spirit of the present invention, which are common in the art. It will be apparent to those who have knowledge.

Claims (14)

Silicon nitride phosphor comprising a compound represented by the formula (1) to be excited by the first light to emit light:
[Formula 1]
Sr _2-x A _x SiN ₄
A is an active agent of any one or two or more combinations selected from the group consisting of Ce, Pr, Eu, Tb, Tm, Yb and Er, wherein 0 <x <2. The method of claim 1,
A is Eu, and the silicon nitride phosphor is a red light emitting phosphor. The method of claim 2,
The light emitting peak of the red light emitting phosphor comprises a light emitting peak of 623nm silicon nitride phosphor. The method of claim 1,
And the first light has a wavelength belonging to any one or a combination of the near ultraviolet band and the blue light band. Silicon nitride phosphor comprising a compound represented by the formula (2) to be excited by the first light to emit light:
(2)
M _{2 - x} A _x SiN ₄
M is any one or a combination of two or more selected from the group consisting of Sr, Ca, Ba and Mg,
A is an active agent of any one or two or more combinations selected from the group consisting of Ce, Pr, Eu, Tb, Tm, Yb and Er, wherein 0 <x <2. The method of claim 5, wherein
And the phosphor compound is deoxygenated. The method of claim 5, wherein
A is Eu, and the silicon nitride phosphor is a red light emitting phosphor. Mixing the carbonate precursor of metal M, the nitride precursor of Si and the oxide precursor of activator A; And
Method of manufacturing a silicon nitride phosphor comprising the step of sintering the mixed product to form a compound represented by the formula
(3)
M _{2 - x} A _x SiN ₄
M is any one or a combination of two or more selected from the group consisting of Sr, Ca, Ba and Mg,
A is an active agent of any one or two or more combinations selected from the group consisting of Ce, Pr, Eu, Tb, Tm, Yb and Er, wherein 0 <x <2. The method of claim 8,
The sintering method of producing a silicon nitride phosphor, characterized in that carried out in a nitrogen atmosphere. The method of claim 8,
The sintering method of producing a silicon nitride phosphor, characterized in that carried out at normal pressure. The method of claim 8,
The sintering method of the silicon nitride phosphor, characterized in that performed at 1700 ℃ to 1800 ℃. The method of claim 8,
The carbonate precursor of Sr comprises SrCO ₃ ,
The nitride precursor of Si includes Si ₃ N ₄ ,
The oxide precursor of Eu comprises a Eu ₂ O ₃ Method for producing a silicon nitride phosphor. The light source which emits light which belongs to at least one of a near-ultraviolet region and a blue region, and the silicon of any one of Claims 1-12 which are arrange | positioned on the optical path of the said light source, are excited by the said light, and emit light. An optical device comprising a nitride phosphor. The method of claim 13,
The optical element is an optical element or a display element.

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