KR20160031352A - Oxynitride-based fluorescent material and light emitting apparatus using same - Google Patents

Abstract

An oxynitride-based fluorescent material represented by Sr_(n-y)Si_nO_(3n-3x)N_(2x):Eu_y has a monoclinic crystal form, and discharges a red or yellow red light by being excited by a near-infrared ray or light in a blue range. Also, the fluorescent material is an oxynitride-based red fluorescent having new composition and structure unlike an existing pure nitride-based red fluorescent material. In the formula, 0.6<=n<=1.6, 0.01<=x<=1, and 0.001<=y<=0.6.

Description

TECHNICAL FIELD [0001] The present invention relates to an oxynitride-based fluorescent material, and a light emitting device using the same. BACKGROUND ART [0002]

The present invention relates to an oxynitride-based fluorescent material emitting red light, a method for producing the same, and a light emitting device using the same.

A conventional white light emitting device is a blue light having a sufficiently high energy emitted from the blue light emitting diode of high luminance YAG: a light-emitting diode to excite by the _{(Y 3 Al 5 O 12 Ce} 3+) based phosphor emits yellow light at a yellow region A combination of blue and yellow of the phosphor is used (Korean Patent Registration No. 10-0517271).

However, such a conventional device has a problem in that it emits white light with a cold feeling due to a high color temperature and has poor color rendering index (CRI) and color control ability due to insufficient light emission in a red region and light emission in a blue region It has disadvantages. Therefore, the method of realizing white using the conventional YAG yellow phosphor has been difficult to use as a light source for a display and a light source for a display due to the drawbacks described above. In order to solve the above problems, the method of replacing Y with Gd or Al with Ga has been used, but it has been difficult to improve color control ability and color rendering due to red deficiency. In order to solve the problem of red deficiency, pure nitrides such as CaAlSiN ₃ : Eu ²⁺ and Sr ₂ Si ₅ N ₈ : Eu ²⁺ have been used, and oxides such as Sr ₃ Si ₂ O ₄ N ₂ : Eu ²⁺ have been reported in the literature (XM Wang et al., Inorganic Chemistry, 51, 3540 (2012)).

Korean Registered Patent No. 10-0517271 (September 28, 2005)

 X.M. Wang et al., Inorganic Chemistry, 51, 3540 (2012).

An object of the present invention is to provide an oxynitride-based phosphor which emits red light having a novel structure and composition.

Another object of the present invention is to provide a light emitting device which is excellent in color reproducibility and color rendering property by using the phosphor.

The present invention provides an oxynitride-based phosphor represented by the following general formula (1): ????????

[Chemical Formula 1]

Sr _ny Si _n O _3n-3x N _2x : Eu _y

In Formula 1,

0.6? N? 1.6, 0.01? X? 1, and 0.001? Y? 0.6.

The present invention also provides a light emitting device comprising the oxynitride-based fluorescent material.

The phosphor of the present invention can be excited by light in the near ultraviolet or blue region to emit red or yellow red light. Unlike the conventional red phosphor, which is a pure nitride phosphor, the phosphor of the present invention is an oxynitride-based red phosphor, and is a phosphor of a novel structure which has not been known yet.

Fig. 1 is an optical microscope photograph of the phosphor prepared in Example 1. Fig.
Fig. 2 is an optical microscope showing that the phosphor prepared in Example 1 emits light with excitation light having a wavelength of 365 nm. Fig.
Fig. 3 shows a single crystal XRD pattern of a red emitting phosphor in the phosphor prepared in Example 1. Fig.
4 compares the powder XRD pattern of the phosphor prepared in Example 1 with the XRD pattern designed by single crystal analysis.
5 is a schematic view showing the structure of the phosphor prepared in Example 1. Fig.
Figure 6 shows the ac side of the structure of Figure 5;
7 is a view showing a bonding structure between O-Sr.
Figure 8 shows the structure of Figure 6 at a slight angle.
FIG. 9 shows a PL (photo luminescence) spectrum of the phosphor prepared in Example 1. FIG.
10 shows the CL (cathode luminescence) spectrum of the phosphor prepared in Example 1. Fig.
Fig. 11 shows a Raman spectrum (right curve) of the phosphor prepared in Example 1. Fig.
12 is an SEM photograph of the phosphor prepared in Example 2. Fig.
13 shows the XRD pattern of the phosphor prepared in Example 2. Fig.
Fig. 14 shows PL spectra of the phosphor prepared in Example 2. Fig.

Hereinafter, the present invention will be described more specifically.

The oxynitride-based fluorescent material of the present invention is represented by the following formula (1)

[Chemical Formula 1]

Sr _ny Si _n O _3n-3x N _2x : Eu _y

0.6? N? 1.6, 0.01? X? 1, and 0.001? Y? 0.6 in the above formula (1).

Preferably, in Formula 1, 0.6? N? 1.6, 0.03? X? 0.7, and 0.01? Y? 0.4.

In this case, n> y in formula (1), and n> x.

When n = 1, it is preferable that 0.15 < x < 0.25. For example, when n = 1 and y = 0.013, a SrSiO ₃ : Eu phosphor can be formed if x is 0.15 or less, and a SrSi ₂ O ₂ N ₂ : Eu phosphor can be formed if x is 0.25 or more , And when x is 0.4 or more, a Sr ₃ Si ₂ N ₄ O ₂ : Eu phosphor can be formed.

As a preferable example, n = 1, x = 0.088 and y = 0.013 in the above formula (1). That is, the oxynitride-based fluorescent material is Sr _{0 .987} Eu _{0 .013} Si ₂ O _{3 .736} N _{0 . 176} &lt; / RTI &gt;

In the above formula (1), any one of Mn, Ce, Cr, Tm, Pr, Yb, Dy, Sm and Tb may be used instead of Eu or a combination thereof. In addition, P may be used instead of Si in order to compensate for the vacancy lattice point of oxygen in Formula 1, and La-based metal may be used instead of Sr.

In the present invention, "oxynitride-based fluorescent substance" means a fluorescent substance having a composition including oxygen and nitrogen that emits light in the range of 550 nm to 750 nm. However, accurate analysis of the ratio of oxygen to nitrogen may be difficult.

The oxynitride-based fluorescent material of the present invention may have a monoclinic crystal form. In addition, the monoclinic crystal form may have a space group of P21 / m. As a specific example, the oxynitride-based red phosphor of the present invention may have a crystal form as shown in Table 1 and Fig. 5 of Example 1 described later.

The phosphor of Formula 1 (for example, when n = 1, x = 0.088 and y = 0.013) has a unit lattice edge length (lattice constant) of 6.8 Å ≤ a ≤7.1 Å, 3.9 Å b ≤4.1 Å, And more specifically, 6.93A? A? 7.03A, 4.05A? B? 4.1A, and 10.17A? C? 10.27A, for example, a = 6.9814A, b = 4.0721 ANGSTROM and c = 10.2205 ANGSTROM.

Further, it is also possible to have? = 90 deg., 95 deg.?? T = 115 deg. And? = 90 deg., And preferably? = 90 deg., 100 deg. 110 ° and γ = 90 °, more preferably α = 90 °, 102 ° ≦ β ≦ 106 ° and γ = 90 °, in particular α = 90 °, β = 103.9 ° and γ = 90 °.

In the present invention, a, b and c, which are the unit cell lattice constant (lattice constants), mean the width, height and height interval (inter-lattice distance) between atoms in a crystal in which molecules of the same shape and structure are gathered, The lattice constants and angles can be adjusted accordingly.

In addition, the oxynitride-based fluorescent material may have an average bond length between Sr and O ranging from 2.50 to 2.65 Å. Specifically, the average bond length between Sr and O may be from 2.50 to 2.62 Å, or from 2.63 to 2.65 Å.

The oxynitride-based red phosphor of the present invention may have a plate shape, a spherical shape, a polygonal shape, a rod shape, or the like.

The oxynitride-based red phosphor of the present invention may have an average particle diameter ranging from 1 탆 to 100 탆, for example, from 3 탆 to 30 탆, and more preferably from 5 탆 to 20 탆 . When a phosphor having an average particle diameter in the above preferable range is used for a light emitting device, a light emitting device having a high light flux can be obtained. These average particle diameters may be diameters based on D ₅₀ .

The oxynitride-based red phosphor of the present invention can emit light with sufficient excitation by near-ultraviolet or blue light, for example, light in the range of 300 to 500 nm, thereby emitting red or yellow red light. According to one example, the oxynitride-based red phosphor of the present invention can emit light in the range of 550 nm to 750 nm, for example, in the range of 600 nm to 700 nm. Further, the maximum peak of the luminescent region can be located at about 600 nm to 660 nm. The luminescent region and the maximum peak can be controlled according to the composition ratios n, x, y of the above formula (1).

The oxynitride-based fluorescent material of the present invention has a new crystal form and lattice constant different from those of conventional phosphors. The oxynitride-based fluorescent material according to the present invention may be excited by light in the near ultraviolet or blue region to emit red or yellow red light. Therefore, the phosphor of the present invention can provide white light of high color rendering when it is combined with a light emitting diode emitting near ultraviolet light or blue light.

The oxynitride-based fluorescent material of the present invention can be produced by a method including the following steps:

(a) mixing and pulverizing raw materials in a chemical equivalent ratio,

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

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

In the step (a), the raw material is mixed and pulverized according to a desired chemical equivalent ratio.

The raw material is a compound containing each of Sr, Si and Eu, and may be, for example, nitride, oxide, nitrate, or carbonate thereof. At least one of the raw materials One of them is preferably a nitride or an oxide.

Specific examples of the compound containing Sr, may be mentioned _{SrO, SrCO 3, Sr (NO} 3) 2, Sr 3 N 2, SrCl 2 , and mixtures thereof. Specific examples of the compounds containing Si are _{SiO 2, Si (NO 3)} 4, Si 3 N 4, SiCl 4 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, EuCl ₂ , EuCl ₃ and mixtures thereof. The mixing molar ratio of these raw materials can be suitably adjusted according to the composition of the phosphor to be finally obtained.

In the mixing and pulverizing, a mortar bowl or a ball milling may be used for uniform mixing.

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

The high-temperature firing is preferably performed at a temperature of 1,300 ° C to 2,000 ° C in a nitrogen atmosphere of 1 to 100 bar through an electric furnace, using a boat of high purity alumina, carbon, BN, molybdenum, tungsten or the like . Further, it is preferable to carry out the calcination for 1 to 30 hours at the temperature in the above range, with the temperature rise time being 1 to 8 hours. Further, the temperature lowering time to room temperature may be 1 to 100 hours. When the pressure range and the firing temperature are within the above-mentioned preferable range, carbide, nitride, etc. generated from the raw material are well removed during firing, so that a single phase crystal lattice suitable for the chemical equivalent ratio is well formed, and the luminescence brightness and chemical bonding force can be improved.

The step (c) is a step of grinding (pulverizing) the fired product obtained above to obtain a final phosphor powder. Specifically, the fired product having been subjected to the firing step can be naturally cooled to room temperature, removed from the firing furnace, and then pulverized (crushed) by ball milling or the like.

According to the above production method, a phosphor powder excellent in particle shape and uniformity and excellent in light efficiency can be obtained.

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, the phosphor of the present invention can be applied to near-ultraviolet or blue LEDs to constitute a light-emitting device. Further, the phosphor may be provided with a green (or greenish-yellow) light-emitting phosphor to constitute a white light-emitting device.

Accordingly, the present invention provides a light emitting device comprising the phosphor of the present invention. As a specific example, the light emitting device may be configured to include a blue LED and a phosphor of the present invention applied on the blue LED and a green phosphor.

Such a light emitting device can be manufactured by a method including the following:

(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 resulting phosphor mixture with a blue LED.

In the step (b), the phosphor mixture may be coated with a blue LED by molding a coating agent using a light-transmissive resin.

The light emitting device of the present invention can emit a warm white light with higher color gamut and better color controllability than the conventional one by using the oxynitride-based red phosphor having excellent luminescence.

Hereinafter, the present invention will be described in more detail by way of examples. The following examples are illustrative of the present invention, but the present invention is not limited to the following examples.

Example 1: Preparation of Sr _0.987 Eu _0.013 SiO _2.736 N _0.176 Manufacturing

SrCO ₃ , SiO ₂ , Si ₃ N ₄ and Eu ₂ O ₃ as raw materials were evenly mixed in ethanol at a molar ratio of 4.9: 6: 1.5: 0.1 for 30 minutes. This was dried to prepare a pellet and charged into a carbon crucible. The prepared crucible was heated in a firing furnace for 2 hours and 26 minutes, held at 1460 ° C for 10 hours and cooled to 660 ° C for 8 hours. Thereafter, it was naturally cooled to room temperature. At this time, nitrogen gas was introduced at 200 mL / min. As a result, a phosphor having a composition of Sr _0.987 Eu _0.013 SiO _2.736 N _0.176 was obtained.

An optical microscope photograph of the phosphor prepared is shown in Fig. FIG. 2 shows a photograph of a red light emission by irradiating an excitation wavelength of 365 nm. Figure 3 shows the results of a single crystal XRD pattern for red emitting particles.

The XRD patterns of the phosphor powders produced are shown in FIG. 4, and XRD patterns simulated through single crystal analysis are shown in FIG. 4 for comparison.

The crystal structure, lattice constant, space group and β value of the red phosphorescent phosphor particles were analyzed and the results are shown in Table 1, and a schematic diagram of the structure is shown in FIG. FIG. 6 shows the ac surface in FIG. 5, and FIG. 7 shows the bonding structure between O-Sr. Figure 8 shows the structure of Figure 6 at a slight angle. 9 shows the PL (photo luminescence) spectrum of the phosphor produced (dotted line is excitation spectrum and solid line is luminescence spectrum), and FIG. 10 shows a CL (cathode luminescence) spectrum. In Fig. 11, the Raman spectrum (right curve) is shown along with the CL spectrum.

2 and 9 to 11, it was confirmed that the phosphor emits red light.

Crystal system Monoclinic system Space group P21 / m
Lattice constant a = 6.9814 A b = 4.0721Å c = 10.2205 beta 103.9 DEG

Example 2: Preparation of Sr _0.98 Eu _0.02 SiO _2.50 N _0.33 Manufacturing

As the raw material SrO, SiO _2, Si ₃ N ₄ and Eu ₂ O ₃ 11.76 to 9: 1 were mixed in a mole ratio of 0.12, were uniformly pulverized using a mortar. Subsequently, a tungsten boat was used and fired in a furnace at a temperature of 1,400 ° C. and a nitrogen pressure of 5 bar for 2 hours. The obtained fired product was placed in distilled water and subjected to ball milling treatment by using a stirrer to obtain a phosphor of Sr _0.98 Eu _0.02 SiO _2.50 N _0.33 composition.

SEM (scanning electron microscope) image and XRD pattern of the phosphor prepared are shown in Figs. 12 and 13, respectively.

The photoluminescence spectrum of the phosphor prepared is shown in Fig. It was found that light was absorbed in the near ultraviolet to blue region of 350 nm to 500 nm and emitted at a red-yellow region (maximum peak: 652 nm) of 600 nm to 700 nm. This corresponds to the emission region originating from the transition of 4f ⁶ 5d-5f ⁷ of Eu ²⁺ .

Manufacturing Example: Fabrication of Light Emitting Device

The oxynitride-based red phosphor prepared in Example 1 was mixed with a green phosphor and a light-transmitting polymer resin.

The resulting phosphor mixture was combined with a blue LED chip to prepare a light emitting device.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, It is to be understood that the invention may be practiced within the scope of the appended claims.

Claims (14)

An oxynitride-based fluorescent material represented by the following formula (1): ????????
[Chemical Formula 1]
Sr _ny Si _n O _3n-3x N _2x : Eu _y
In the above formula
0.6? N? 1.6, 0.01? X? 1, and 0.001? Y? 0.6.
The method according to claim 1,
Wherein in the formula (1), 0.6? N? 1.6, 0.03? X? 0.7, and 0.01? Y? 0.4.
3. The method of claim 2,
Wherein n = 1, x = 0.088 and y = 0.013 in the formula (1).
The method according to claim 1,
Wherein the oxynitride-based fluorescent material has a monoclinic crystal form.
5. The method of claim 4,
Wherein the monoclinic crystal form has a space group of P21 / m.
5. The method of claim 4,
6. The oxynitride-based fluorescent material according to claim 1, wherein the monoclinic crystal form has a unit cell edge length of 6.8? A? 7.1, 3.9? B? 4.1 and 10.1? C?
The method according to claim 6,
6. The oxynitride-based fluorescent material according to claim 1, wherein the unit lattice edge length is 6.93? A? 7.03, 4.05? B? 4.1 and 10.17? C? 10.27.
5. The method of claim 4,
Wherein the monoclinic crystal type has angles? = 90 deg., 100 deg.?? 110 deg., And gamma = 90 deg. As angles between unit lattice corners.
9. The method of claim 8,
Wherein the angle between the unit lattice corners is? = 90 °,? = 103.9 ° and? = 90 °.
The method according to claim 1,
Wherein the oxynitride-based fluorescent material has an average bond length between Sr-O of 2.50 Å to 2.65 Å.
The method according to claim 1,
Wherein the oxynitride-based fluorescent material has a luminescent region in a range of 550 nm to 750 nm.
12. The method of claim 11,
Wherein the light emitting region has a maximum peak in the range of 600 nm to 660 nm.
13. The method of claim 12,
Wherein the oxynitride-based fluorescent material absorbs excitation light in the range of 300 nm to 500 nm.
A light emitting device comprising the oxynitride-based fluorescent material according to any one of claims 1 to 13.

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