KR102219263B1 - Acidic nitride-based red fluorescent material and white light emitting apparatus using same - Google Patents

Abstract

The oxynitride-based red phosphor having an orthorhombic crystal structure and represented by the following formula (1) is excited by near ultraviolet or blue light to emit red or yellow-red light. It is excellent, and the light emission efficiency hardly decreases even under severe conditions such as high temperature and high humidity. Accordingly, the white light emitting device including the phosphor can emit warm white light with higher luminance than the conventional one, and has excellent color rendering, color reproducibility and color control:
[Formula 1]
A ₂ Si ₄ AlON ₇ :zEu ²⁺
In the above formula,
A is Sr, Ba or a combination thereof,
0.001≤z≤0.3.

Description

An oxynitride-based red phosphor and a white light emitting device using the same {ACIDIC NITRIDE-BASED RED FLUORESCENT MATERIAL AND WHITE LIGHT EMITTING APPARATUS USING SAME}

The present invention relates to an oxynitride-based red phosphor, a manufacturing method thereof, and a white light emitting device using the same.

In a conventional white light emitting device, blue light having sufficiently high energy emitted from a high-brightness blue light emitting diode _{excites a YAG (Y 3} Al ₅ O ₁₂ :Ce ⁺³ )-based yellow phosphor to emit light in the yellow region. A method of converting to white by a combination of blue and yellow phosphor was used (Korean Patent Publication No. 10-0517271).

However, as such conventional devices lack light emission in the red region and dominance in light emission in the blue region, they emit cool white color due to a high color temperature, and have poor color rendering index (CRI) and color control capability. Has drawbacks. Therefore, it has been difficult to use a conventional YAG-based yellow phosphor to implement white color as a light source for a display and a light source for illumination due to the above disadvantages. In order to solve the above problem, a method of substituting Y for Gd or Al for Ga was used, but there was a difficulty in improving color tone and color rendering.

Republic of Korea Patent Publication No. 10-0517271 (Nichia Kagaku High School Co., Ltd.) 2005.09.28.

Accordingly, an object of the present invention is to provide a red phosphor of a new composition having excellent light emission efficiency.

Another object of the present invention is to provide a white light emitting device that emits warm white light having excellent color reproducibility and color rendering properties by using the red phosphor.

In accordance with the above object, the present invention provides an oxynitride-based red phosphor having an orthorhombic crystal structure and represented by the following Formula 1:

In the above formula,

A is Sr, Ba or a combination thereof,

0.001≤z≤0.3.

According to the above other object, the present invention provides a white light emitting device comprising the oxynitride-based red phosphor.

The phosphor of the present invention is excited by near-ultraviolet or blue light to emit red or yellow-red light, and the light-emitting area moves to a longer wavelength than before, so it has excellent color rendering properties, and light even under severe conditions such as high temperature and high humidity. The luminous efficiency hardly decreases. Accordingly, the white light-emitting device including the phosphor can emit white light having a higher color rendering property than the conventional one, and has excellent color gamut and color control.

1 is a schematic diagram showing the crystal structure of the phosphor prepared in Example 1.
2 and 3 show a scanning electron microscope (SEM) image and XRD analysis results of the phosphor prepared in Example 1, respectively.
4 is a comparison of light emission spectra of the phosphors prepared in Examples 1 and 3.
5 shows an SEM image of the phosphor prepared in Example 3.
6 shows a light emission spectrum of the phosphor prepared in Comparative Example 1.

Oxynitride-based red phosphor

The oxynitride-based red phosphor of the present invention is represented by the following formula (1):

[Formula 1]

A ₂ Si ₄ AlON ₇ :zEu ²⁺

In the above formula,

A is Sr, Ba or a combination thereof,

0.001≤z≤0.3, preferably 0.01≤z≤0.2.

The oxynitride-based red phosphor of the present invention may have an orthorhombic crystal structure of the space group of Pmn21. Accordingly, the XRD analysis result of the oxynitride-based red phosphor of the present invention may be consistent with the pattern of Joint Committee on Powder Diffraction Standard (JCPDS) # 85-0101. However, as part of the Si-N tetrahedron is substituted with the Al-O tetrahedron, it has a crystal structure as shown on the right side of FIG. 1. From FIG. 1, according to one embodiment of the present invention, a nitride-based red phosphor, Sr ₂ Si ₅ N ₈ :zEu ²⁺ phosphor, and a part of the Si-N tetrahedron in the phosphor structure is substituted with Al-O tetrahedron. The difference in the crystal structure between the Sr ₂ Si ₄ AlON ₇ :zEu ^{2+ phosphors can be confirmed.}

When A is Sr in Formula 1, the interstitial distances a, b, and c of the crystal structure of the phosphor may be 5.6650 to 5.8650Å, 6.6571 to 6.8571Å, and 9.3964 to 9.5964Å, respectively, for example, a=5.7650Å, b =6.7571Å, may be c=9.4964Å.

The oxynitride-based red phosphor of the present invention may be in the form of a powder. 2 is an example of an SEM image of an oxynitride-based red phosphor according to the present invention.

The oxynitride-based red phosphor of the present invention may have a rod-shaped shape, as can be seen from the SEM image of FIG. 2, and the average particle diameter of the powder may be in the range of 1 μm to 20 μm, for example 3 It may be in the range of ㎛ to 15㎛, if more limited, it may be in the range of 5㎛ to 15㎛. These average particle diameters may be D ₅₀ standard particle diameters.

The oxynitride-based red phosphor of the present invention may be coated with an inorganic material, particularly an inorganic oxide, in order to improve heat resistance and durability. The coatable inorganic oxide may be silica (SiO ₂ ), alumina (Al ₂ O ₃ ), magnesia (MgO), or a mixture thereof. The coating thickness may be 10 nm to 500 nm, more preferably 100 nm to 300 nm.

The oxynitride-based red phosphor of the present invention can be sufficiently excited by near ultraviolet or blue light, for example, light in the region of 350 nm to 500 nm to emit light, thereby emitting red or yellow-red light. According to an example, the oxynitride-based red phosphor of the present invention may emit light in a range of 550 nm to 750 nm, for example, 550 nm to 700 nm, or 580 nm to 680 nm. In addition, the maximum peak of the emission region may be located at about 610 nm to 670 nm. The emission region and the maximum peak may be adjusted according to the type and composition ratio of the elements constituting A of Formula 1, and the content of Eu.

The oxynitride-based red phosphor of the present invention has very excellent photoluminescence efficiency, for example, the photoluminescence efficiency at room temperature (25°C) is superior to that of conventional phosphor products.

In addition, the photoluminescence efficiency hardly decreases even under thermal quenching conditions, and, for example, the photoluminescence efficiency at 180°C may be maintained at 95% or more compared to the photoluminescence efficiency at room temperature.

In addition, the photoluminescence efficiency hardly decreases even under wet aging conditions, and the photoluminescence efficiency after immersion in hot water at 300℃ for 30 minutes is 95% compared to the photoluminescence efficiency at room temperature. It can be kept above.

The oxynitride-based red phosphor according to the present invention is excited by near-ultraviolet or blue light to emit red or yellow-red light, and has improved light luminous efficiency than before, resulting in excellent luminance, Even under severe conditions such as, the light emission efficiency hardly decreases. In addition, since the oxynitride-based red phosphor of the present invention is formed in a single phase, the chemical bonding force between the ions is strong, so that the chemical properties are stable, and the luminance and reproducibility of the emission spectrum are excellent.

Accordingly, when the phosphor of the present invention is combined with a light emitting diode emitting near ultraviolet or blue light, white light having high color rendering can be provided.

Manufacturing method of oxynitride-based red phosphor

The phosphor of the present invention can be prepared by a method comprising the following steps:

(a) mixing and pulverizing the raw material according to the chemical equivalent ratio,

(b) firing the obtained raw material mixture at high temperature in a nitrogen atmosphere, and

(c) pulverizing the obtained fired product to obtain a phosphor powder.

The step (a) is a step of mixing and pulverizing the raw material according to a desired chemical equivalent ratio.

The raw material is a compound containing each of A, Si, Al, and Eu, and may be, for example, nitride, oxide, nitrate, or carbonate thereof. At least one of them is nitride or oxide.

Specific examples of the compound containing A include AO, ACO ₃ , A(NO ₃ ) ₂ , A ₃ N ₂ and mixtures thereof.

Specific examples of the compound containing Si include SiO ₂ , Si(NO ₃ ) ₄ , Si ₃ N _4, and mixtures thereof.

Specific examples of the compound containing Al include Al ₂ O ₃ , Al(NO ₃ ) ₃ , AlN, and mixtures thereof.

Specific examples of the compound containing Eu include Eu ₂ O ₃ , EuN, EuF ₃ , Eu ₂ (CO ₃ ) ₃ , Eu(NO ₃ ) ₃ and mixtures thereof.

The mixing molar ratio of these raw materials can be appropriately adjusted according to the composition of the phosphor desired to be finally obtained.

For the mixing and grinding, a mortar or ball milling may be used for uniform mixing.

The step (b) is a step of firing the raw material mixture obtained above at high temperature in a nitrogen atmosphere.

The high-temperature firing is preferably carried out at a temperature of 1300°C to 2000°C in a nitrogen atmosphere of 1 to 100 bar through an electric furnace using a boat made of a material such as high purity alumina, carbon, BN, molybdenum, tungsten, etc. . Moreover, it is preferable to set the temperature rising time to 1 to 8 hours, and to fire for 1 to 30 hours at a temperature in the above range. When the pressure range and the firing temperature are within the above preferred ranges, carbides, nitrides, etc. generated from the raw material during firing are well removed, thereby forming a single-phase crystal lattice having a suitable chemical equivalent ratio, thereby improving luminance and chemical bonding.

The step (c) is a step of pulverizing (disintegrating) the obtained fired product to obtain a final phosphor powder. Specifically, the fired product after the firing step is naturally cooled to room temperature, taken out from an electric furnace, and then pulverized (crushed) using ball milling or the like.

The phosphor powder may be coated with an inorganic material afterwards, and may be coated with an appropriate thickness using _{, for example, silica (SiO 2 ).}

The phosphor powder obtained according to the above manufacturing method has excellent particle shape and uniformity, and thus has high luminous efficiency and brightness.

White light emitting device and manufacturing method thereof

The phosphor of the present invention can be used as a color conversion phosphor of a near ultraviolet or blue light emitting diode (LED). Accordingly, when the phosphor of the present invention is applied to near ultraviolet or blue LED to emit red light, when provided with a green (or greenish yellow) light emitting phosphor, a white light emitting device can be configured.

Accordingly, the present invention provides a white light emitting device comprising the phosphor of the present invention. More specifically, the present invention provides a blue LED, and a white light emitting device comprising the phosphor of the present invention and a green phosphor coated on the blue LED.

Such a white light emitting device can be manufactured by a method comprising:

(a) mixing the oxynitride-based red phosphor of the present invention with a green phosphor (or a green phosphor and a yellow phosphor); And

(b) combining the obtained phosphor mixture with a blue LED.

In the step (b), the phosphor mixture may be coated or molded on a blue LED after making a coating agent using a light-transmitting resin.

The white light-emitting device of the present invention can emit warm white light with higher color rendering than before, and has excellent color gamut and color control properties, as the nitride-based red phosphor having excellent luminescence is used.

Hereinafter, the present invention will be described in more detail by examples. However, the following examples are merely illustrative of the present invention, and the contents of the present invention are not limited to the following examples.

Example 1: Sr ₂ Si ₄ AlON ₇ :0.1Eu ²⁺ Manufacturing of -(1)

As raw materials, Sr ₃ N ₂ , Si ₃ N ₄ , AlN, and Eu ₂ O ₃ were mixed at a molar ratio of 2.3:5:3.5:0.1, and pulverized evenly using a mortar. Thereafter, the heating time was set to 6 hours in an electric furnace using a tungsten boat and fired for 2 hours in a nitrogen atmosphere at 1900°C and 10 bar. The resulting fired product was put in distilled water, pulverized using a stirrer, and ball-milled to obtain a phosphor having a composition of _{Sr 2} Si ₄ AlON ₇ : 0.1Eu ^2+.

SEM (scanning electron microscope) images and X-ray diffraction analysis (XRD analysis) results of the produced phosphor are shown in FIGS. 2 and 3, respectively.

From the SEM image of FIG. 2, it can be seen that the phosphor is in the form of a rod, and from the results of the XRD analysis of FIG. 3, it can be seen that the pattern matches the pattern of Joint Committee on Powder Diffraction Standard (JCPDS) # 85-0101. have. From this, it can be seen that the phosphor of Example 1 is structurally orthorhombic in the space group of Pmn21 and has a single phase structure. The interstitial distances a, b, and c of the crystal structure of the phosphor were 5.7650 Å, 6.7571 Å, and 9.4964 Å, respectively.

Example 2: Sr ₂ Si ₄ AlON ₇ :0.1Eu ²⁺ Manufacturing of -(2)

As raw materials, Sr ₃ N ₂ , Si ₃ N ₄ , Al ₂ O ₃ , and Eu ₂ O ₃ were mixed at a molar ratio of 1.9: 4.4: 0.6: 0.05 and pulverized evenly using a mortar. Thereafter, the heating time was set to 6 hours in an electric furnace using a tungsten boat and fired for 2 hours in a nitrogen atmosphere of 1500°C and 10 bar. The resulting fired product was put in distilled water, pulverized using a stirrer, and ball-milled to obtain a phosphor having a composition of _{Sr 2} Si ₄ AlON ₇ : 0.1Eu ^2+.

The light emission spectrum of the prepared phosphor is shown in FIG. 4. As shown in FIG. 4, it was found that light was absorbed in the near ultraviolet to blue region of 350 nm to 500 nm (maximum peak 450 nm), and emitted in the yellow-red region (maximum peak 645 nm) of 580 nm to 700 nm. This corresponds to the light emitting region resulting from the transition of 4f ⁶ 5d-5f ^{7 of Eu 2+.}

Example 3: Ba ₂ Si ₄ AlON ₇ :0.1Eu ²⁺ Manufacture of

It was carried out in the same procedure as in Example 1, except that Ba ₃ N _{2 was used instead of Sr 3} N _{2 of the} raw material, and the mixing molar ratio of the raw material was appropriately adjusted, and the composition of _{Ba 2} Si ₄ AlON ₇ : 0.1Eu ² A phosphor was obtained.

The light emission spectrum and SEM image of the prepared phosphor are shown in FIGS. 4 and 5, respectively. From the light emission spectrum of FIG. 4, it was confirmed that the phosphor of Example 3 moved to a shorter wavelength than the phosphor of Example 1, and from the SEM image of FIG. 5, it was found that the phosphor was grown in a needle shape.

Example 4: (Sr,Ba) ₂ Si ₄ AlON ₇ :0.1Eu ²⁺ Manufacture of

Performed in the same procedure as in Example 1, but _{by additionally using Ba 3} N ₂ as a raw material and appropriately adjusting the mixing molar ratio of the raw material, (Sr, Ba) ₂ Si ₄ AlON ₇ : 0.1Eu ²⁺ composition A phosphor was obtained.

As a result of measuring the light emission spectrum of the phosphor of Example 4, Sr ₂ Si ₄ AlON ₇ : 0.1Eu ²⁺ composition Although the same absorption region as the phosphor was shown, it was confirmed that the emission wavelength shifted to a shorter wavelength due to the addition of Ba.

Comparative Example 1: Sr ₂ Si ₅ N ₈ :0.01Eu ²⁺ Manufacture of

It was carried out in the same procedure as in Example 1, but as raw materials, Sr ₃ N ₂ , Si ₃ N ₄ , Eu ₂ O ₃ were mixed in a molar ratio of 2: 5: 0.01, and Sr ₂ Si ₅ N ₈ :0.01Eu ²⁺ A red phosphor of the composition was obtained.

The light emission spectrum of the prepared phosphor is shown in FIG. 6. As shown in FIG. 6, it can be seen that the phosphor of Comparative Example 1 has a shorter wavelength compared to the phosphor of Example 1.

Experimental Example 1: Light emission efficiency and color evaluation

Photolumnescence (PL) and CIE color coordinates at room temperature (25° C.) of the phosphors prepared in Example 1 and Comparative Example 1 were measured and summarized in Table 1 below. The photoluminescence value was obtained by integrating the area of the emission peak on the spectrum.

Emission peak area CIE x CIE y Main peak Example 1 47.7 0.644 0.346 643 Comparative Example 1 48.8 0.628 0.361 625

From the CIE x, y coordinate values in Table 1, it can be seen that the phosphor of Example 1 emits light in a long wavelength region, which is compared with the phosphor of Example 1 when configured with a blue LED and a green phosphor. It shows that better color rendering properties than the phosphor of Example 1 can be implemented.

Claims (8)

It has an orthorhombic crystal structure,
The interstitial distances a, b, and c of the crystal structure are 5.6650 to 5.8650 Å, 6.6571 to 6.8571 Å, and 9.3964 to 9.5964 Å, respectively,
An oxynitride-based red phosphor represented by the following formula (1):
[Formula 1]
Sr ₂ Si ₄ AlON ₇ :zEu ²⁺
In the above formula,
0.001≤z≤0.3. The method of claim 1,
The oxynitride-based red phosphor, characterized in that the oxynitride-based red phosphor has a rod-shaped shape. delete The method of claim 1,
The oxynitride-based red phosphor, characterized in that the interstitial distances a, b, and c of the crystal structure are 5.7650 Å, 6.7571 Å, and 9.4964 Å, respectively. The method of claim 1,
The oxynitride-based red phosphor, characterized in that z is a value in the range of 0.01 to 0.2. The method of claim 1,
An oxynitride-based red phosphor, characterized in that the oxynitride-based red phosphor is coated with an inorganic oxide. The method of claim 1,
An oxynitride-based red phosphor, characterized in that the oxynitride-based red phosphor has a light emitting region in the range of 550 nm to 750 nm. A white light emitting device comprising the oxynitride-based red phosphor of any one of claims 1, 2, and 4 to 7.

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