KR100937240B1 - Ynbo4 systems with enhanced red emission properties and white light emitting diodes using the same - Google Patents

Abstract

PURPOSE: A red phosphor is provided to high red light emitting strength compared with a conventional YNbO4:Eu^(3+) fluorescent substance, thereby being used for a light emitting diode using a near ultraviolet ray chip and a blue chip. CONSTITUTION: A red phosphor has a composition represented by chemical formula 1: Y_(1-x)M_xNbO_4:zEu^(3+). In chemical formula 1, M is Al or Ga; 0<x<1; 0<z<0.5. A method for preparing the red phosphor comprises the steps of: preparing a mixture using Y2O3, Nb2O5 and Eu2O3, and LiCl as a fluxing agent; and ball milling the mixture, and then heat-treating the mixture in a tubular furnace of 1000~1300 °C in a nitrogen atmosphere.

Description

YNBO-based red phosphors with enhanced luminous intensity and white light emitting diodes using them {YNbO4 Systems with Enhanced Red Emission Properties and White Light Emitting Diodes using the Same}

The present invention relates to a white light emitting diode using the same red phosphor and the emission intensity enhancement, more specifically, YNbO _4: addition of increasing the concentration of Eu ^{3 +} in Eu ^{3 +} red phosphor by 50% or Al or Ga The present invention relates to a red phosphor and a white light emitting diode using the same.

A method of making a white light emitting diode includes using a near ultraviolet light emitting diode chip and a blue light emitting diode chip. Both of these methods use phosphors that emit visible light. Europium (Eu) -doped yttrium niobate (YNbO ₄ ) phosphor may be excited in near ultraviolet light and a blue light emitting diode, thereby causing red light emission.

Light emitting diodes (LEDs), which combine a near-ultraviolet (nUV) chip with an RGB (red, green, blue) phosphor mixture, provide excellent color uniformity and high color rendering index for applications in solid-state lighting applications (SSL). rendering index) and superior light quality have been of interest (Tadatomo et al., Jpn. J. Appl. Phys., 40, L583, 2001).

As a result, numerous phosphors for near ultraviolet excitation have been widely developed so far: chlorapatite, alkaline earth metal aluminum, and nitride. In addition, rare earth (rare-earth (RE)) ions ABO ₄ ^- the phosphor of the type, for example, molybdate (molybdates) (Wang et al, J. Electrochem Soc, 152, G186, 2005...), Tungstates (Shi et al., Spectrochim. Acta A, 69, 396, 2008), and niobate (Massabni et al., Mater. Res., 1, 1, 1998) are also near ultraviolet rays. It has been studied for white LED light sources.

They have also been studied as X-ray phosphors over the last few decades, and their luminescence mechanisms are known as [MoO ₄ ] ^2- , [WO ₄ ] ^2- and [NbO ₄ ] ^3- , energy transfers from each excited state. come.

In particular, Eu ^{3 +} is the active molybdate and tungstate are known to the strong emission of red light at a high color purity. Different ABO ₄ - type, Eu ^{3 +} doped YNbO ₄ also comprise a wide CTB (charge transfer band, the charge transfer band) and a fine peak due to the ff transition of Eu ^{3 +,} similar to exhibit strong red luminescence under these here peak Has an optical spectrum of molybdate and tungstate.

YNbO ₄ has two polymorphs: high temperature T phase (T-scheelite, I 4 _{1 / a} ) and low temperature monoclinic distorted M phase (M-fergusonite, C ₂ ). The transition temperature is from 500 to 800 ° C. according to the doped RE ions.

Recently, many studies on molybdate and tungstate phosphors have focused on improving the luminescence intensity under near ultraviolet excitation by the substitution of cations.

A blue chip yellow phosphor of YAG: Ce ^{3 +} combined with the created white LED has been widely commercially available. However, in this case, there is a weakness in the light of the red area, which causes the color rendering index to fall, making it difficult to use the LCD as a back light unit (BLU). To solve this problem, green and red mixed phosphors are used instead of yellow phosphors. In this case, a nitride compound is used as the red phosphor material, but it is expensive and difficult to process (R. Xie and N. Hirosaki, Science and Technology of Advanced Materials, 8, 588-600, 2007).

Under this technical background, the present inventors have YNbO _4: leading to the embodiment efforts result completed the present invention in order to improve the light intensity of the Eu ^{3 +} phosphor.

It is an object of the present invention YNbO _4: Eu ^{3 +} to provide a phosphor with improved emission intensity of the red to increase the concentration of Eu ^{3 +} 50%, or the addition of Al or Ga on the red phosphor.

It is another object of the present invention YNbO _4: there to in Eu ^{3 +} red phosphor provides a method for improving the light emission intensity of the red to increase the concentration of Eu ^{3 +} 50%, or the addition of Al or Ga.

Another object of the present invention to provide a white LED using the red phosphor.

In order to achieve the above object, the present invention provides a red phosphor represented by Formula 1 below:

[Formula 1]

Y _{1 - x} M _x NbO ₄ : zEu ^{3 +}

In Formula 1, M is Al or Ga, x is 0≤x <1, 0 <z <0.5.

In one embodiment of the present invention, the red phosphor, z in Formula 1 is preferably 0.01≤z≤0.45.

In one embodiment of the present invention, x in Chemical Formula 1 is preferably 0.1≤x≤0.4.

In one embodiment of the present invention, when M in the formula (1) is Al is preferably 0.1≤x≤0.3, it is particularly preferable that x = 0.2.

In one embodiment of the present invention, if M in the general formula (1) is Ga is preferably 0.1≤x≤0.2, more preferably x = 0.1.

In one embodiment of the present invention, the red phosphor is prepared by using a Y ₂ O ₃ , Nb ₂ O ₅ and Eu ₂ O ₃ powder, and a mixture using LiCl as a flux; And the ball-mill (ball-mill) treatment of the mixture is preferably prepared by a method comprising the step of heat treatment at 1000 ~ 1300 ℃ in a tube furnace of nitrogen atmosphere.

According to another aspect of the present invention, a white light emitting diode using a near ultraviolet or blue light emitting diode chip, wherein the red phosphor according to the present invention is disposed on the near ultraviolet or blue light emitting diode chip. Is provided.

According to a preferred embodiment of the white light emitting diode according to the present invention, it is preferable that the near ultraviolet light emitting diode chip has a 397 ± 5 nm excitation wavelength and the blue light emitting diode chip has a 466 ± 5 nm excitation wavelength.

According to the present invention, it is possible to provide a phosphor having a red emission intensity higher than that of the conventional YNbO ₄ : Eu ^{3 +} phosphor, and the red phosphor having such excellent emission intensity is useful in a white LED using a near ultraviolet chip and a blue chip. Can be used.

In the present invention, Y _{1 - x} M _x NbO ₄ : zEu ^{3 +} (M: Al, Ga) red phosphor powder was prepared and the charge transfer band (CTB, ~ 270 nm), near ultraviolet (397 ± 5nm) and blue (466 ± 5 nm) red emission (613 nm) characteristics under excitation.

As a result of the increase of Eu content (z), red light emission under CTB, 397 nm, and 466 nm excitation increased rapidly and then gradually decreased, and increased to approximately z = 0.45.

In addition, the red light emission of Y _{1 - x} M _x NbO ₄ : zEu ^{3 +} (M: Al, Ga) is 0.1≤x≤0.4, and the emission intensity is improved by about 10% compared to the case where x = 0. If Al is 0.1≤x≤0.3, and if M is Ga, 0.1≤x≤0.2, the emission intensity is improved by 30 to 60% or more. In particular, in the case of M = Al, when x = 0.2 at M = Ga, the red light emission intensity value was about 2 times higher than when x = 0.1 at x = 0.

This enhanced red emission characteristic is estimated to be due in Al ^{3 +} and locally distorted and asymmetrical spot (asymmetry sites in the host lattice derived from a different ionic radius of Ga ^{+ 3} from the Y ^{3 +.}

In the present invention, a red phosphor represented by the following Chemical Formula 1 is provided:

[Formula 1]

Y _{1 - x} M _x NbO ₄ : zEu ^{3 +}

In Formula 1, M is Al or Ga, x is 0≤x <1, 0 <z <0.5.

At this time, z representing the content of Eu ^{3 +} of the formula 1 is preferably a 0.01≤z≤0.45. In the concentration range as described above Eu ^{3 +,} it is important to manufacture the single phase so as not to accompany the second phase.

According to the prior art YNbO _4: Preparation of a mixture with the H ₃ BO _3, NH ₄ Cl as the manufacture of _{Y 2 O 3, Nb 2 O} 5 , and Eu ₂ O ₃ powder and a flux of Eu ^{3 +} phosphor, and the The mixture is ball-milled and heat-treated in an oxygen atmosphere tube furnace. In addition, the concentration of europium which is an activator is generally set to 15 mol% or less.

However, in the preparation of the YNbO ₄ : Eu ^{3 +} phosphor according to the present invention, especially when LiCl is used as a flux and heat treated at 1000 to 1300 ° C. in a tube furnace in a nitrogen atmosphere, the concentration of europium is increased to 45%. It is possible to prepare a single phase phosphor which is not accompanied by a secondary phase.

In the Y _{1 - x} M _x NbO ₄ : zEu ^{3 +} (M is Al or Ga) red phosphor according to the present invention, when M is Al, the luminescence intensity is approximately compared to the case where Al is not added when it is within the range of 0.1 ≦ _x ≦ 0.3. It increased more than 30-60%, and showed twice the light emission intensity when x = 0.2 than when x = 0 (Figs. 3 to 5).

In addition, when M is Ga, the emission intensity increases by approximately 60% or more compared with the case where Ga is not added (x = 0) when it is within the range of 0.1≤x≤0.2, and when x = 0 when x = 0.1. The emission intensity was about 2 times (Figs. 6 to 8).

Based on the above results, Y _{1 -x} M _x NbO ₄ : zEu ^{3 +} (M is Al or Ga) with enhanced luminous intensity provided by the present invention is a white phosphor using near-ultraviolet or blue light emitting diode chip. Applicable to light emitting diodes.

That is, the red phosphor according to the present invention may be disposed on the near ultraviolet or blue light emitting diode chip to provide a more efficient white light emitting diode.

In the white light emitting diode, a near ultraviolet light emitting diode chip has a wavelength of 397 ± 5 nm, and a blue light emitting diode chip has a wavelength of 466 ± 5 nm.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, these Examples are only for illustrating the present invention, and the scope of the present invention will not be construed as being limited by these Examples.

Production Example  One: Y _{One - z} NbO ₄ : zEu ^{3 +}  Manufacture of red phosphor powder

Y _{1 - z} NbO _4: Use the _{Y 2 O 3, Nb 2 O} 5, Eu 2 O 3 as a raw material for the production of ^{zEu 3 + (0 <z <} 0.5) powder was used as a flux in the LiCl. The prepared mixture was subjected to a ball mill and heat-treated in a nitrogen furnace tube furnace. Europium (Eu) was added as an active agent in the range of 1 to 45 mol%, that is, in the range of 0.01 ≦ z ≦ 0.45.

As described above, LiCl was used as a flux and the heat treatment in a nitrogen atmosphere tube furnace did not produce a secondary phase, unlike a case where an oxygen atmosphere or a flux of H ₃ BO ₃ and NH ₄ Cl was used. .

Production Example  2: Y _{One - x} M _x NbO ₄ : zEu ^{3 +} (M: Al , Ga Manufacture of Red Phosphor Powder

Y _1-x M _x NbO ₄ : zEu ³⁺ (M: Al, by burning a stoichiometric mixture of Y ₂ O ₃ , Nb ₂ O ₅ , Al ₂ O ₃ , Ga ₂ O ₃ , and Eu ₂ O ₃ powders Ga) powder was prepared. LiCl (7 wt%) was added as a flux to promote the solid state reaction and fluorescence properties by allowing the increased diffusion coefficient to accelerate the mechanical rate for the production of the compound. The amount of Eu ₂ O ₃ produced a mixed sample in the range of 0 to 45 mol%. The mixture was ball-milled for 24 hours and then burned at 1300 ° C. in an electric furnace into which nitrogen gas was introduced for 12 hours. After heat treatment, a sufficient pulverization treatment yielded a red phosphor having a composition of Y _{1 - x} M _x NbO ₄ : zEu ^{3 +} (M: Al, Ga).

Test Example  One: YNbO ₄ : Eu ^{3 +} of PL  ( Photoluminescence Characteristic measurement

The Y ₁ prepared in Preparative Example 1 _{- z} NbO _4: was measured ^{zEu 3 + (0 <z <} 0.5) PL (Photoluminescence) characteristics of the powder, the PL system using a xenon (xenon) lamp as this material as measured Was used.

1 shows red light emission intensity according to Eu concentration (z value) of Y _{1 - z} NbO ₄ : zEu ^{3 +} (0 <z <0.5) powder when the excitation wavelength is 397 nm and the emission wavelength is 613 nm. 2 shows the red light emission intensity according to the Eu concentration (z value) of Y _{1 - z} NbO ₄ : zEu ^{3 +} (0 <z <0.5) powder at an excitation wavelength of 466 nm and emission wavelength of 613 nm.

As shown in FIG. 1, the excitation at 397 nm, which is near ultraviolet light, showed a sharp increase in red emission intensity of 613 nm to 25 mol% (z = 0.25), and the emission intensity was higher at europium concentration of 25 mol% or more. It hardly increased over. When the excitation wavelength was excited at 466 nm blue wavelength, the emission intensity rapidly increased to 20 mol% (z = 0.2) and gradually increased even at europium concentrations of 20 mol% or more.

As described above, it was possible to dope europium concentration up to 45 mol% (z = 0.45) without generating a secondary phase, and as a result, a very strong red light-emitting phosphor was obtained at 397 nm, which is near ultraviolet light, and 466 nm, which is blue. .

Test Example  2: YAlNbO ₄ : Eu ^{3 +} of PL  Property measurement

The Y ₁ prepared in Preparative Example _{2 - x Al x NbO 4:} Eu 3 + (0≤x <1) were measured PL (Photoluminescence) characteristics of the powder, PL using a xenon (xenon) lamp as this material as measured The system was used.

Figure 3 in _{Y 1 - x Al x NbO 4} : shows the excitation spectra of the Al addition amount (x) of Eu ^{3 +} (0≤x <1) powder.

As can be seen through Figure 3, by adding Al to YNbO ₄ : Eu ^{3 +} to have a composition of Y _{1 -x} Al _x NbO ₄ : Eu ³⁺ (0≤x <1) according to the result of Al At x = 0.2 the intensities of the 385 nm, 397 nm and 466 nm of the excitation spectrum increased to maximum values.

4 and 5 show emission spectra (excitation wavelengths: 397 nm and 466 nm) according to the amount of Al added (x).

FIG. 4 shows that Y _1-x Al _x NbO ₄ : Eu ³⁺ (0 ≦ x <1) powder was excited at 397 nm, which is near ultraviolet light. Red emission intensity at 613 nm increased with addition of Al, and x = 0.2 It can be seen that the light emission intensity has a value of about 2 times that of Al not added (x = 0).

FIG. 5 shows that Y _1-x Al _x NbO ₄ : Eu ³⁺ (0 ≦ x <1) powder was excited at 466 nm which is blue, and red emission intensity at 613 nm increased with addition of Al, and x = 0.2 It can be seen that has a value of about 1.5 times as compared with the addition of Al (x = 0).

Test Example  3: YGaNbO ₄ : Eu ^{3 +} of PL  Property measurement

The Y ₁ prepared in Preparative Example _{2 - x Ga x NbO 4:} Eu 3 + (0≤x <1) were measured PL (Photoluminescence) characteristics of the powder, PL using a xenon (xenon) lamp as this material as measured The system was used.

Figure 6 is _{Y 1 - x Ga x NbO 4} : shows the excitation spectra of the Ga amount (x) of Eu ^{3 +} (0≤x <1) powder.

According to the result so as to have the composition of the Eu ³⁺ (0≤x <1) Ga amounts: _{- x} Ga _x NbO ₄ Eu ^{+ 3} was added to the Y Ga _1:, YNbO ₄ As can be seen in the Figure 6 At x = 0.1, the intensity of 385 nm, 397 nm and 466 nm of the excitation spectrum showed the maximum value.

7 and 8 show emission spectra (excitation wavelength: 397 nm and 466 nm) according to the amount of Ga addition (x).

FIG. 7 shows that Y _{1 - x} Ga _x NbO ₄ : Eu ^{3 +} (0≤x <1) powder was excited at 397 nm, which is near ultraviolet light, and red light emission intensity at 613 nm increased with addition of Ga, and x = 0.1 It can be seen that has a light emission intensity value of about 2 times compared to that without adding Ga in (x = 0).

8 is a _{Y 1 - x Ga x NbO 4} : Eu 3 + (0≤x <1) to which this powder in the blue 466 nm, depending on the addition of Ga was increased and the red light-emitting intensity at 613 nm = 0.2 x It can be seen that the value of about 2 times compared to that without adding Ga in (x = 0).

Through the results of the above examples, it was possible to dope the concentration of europium in Y _{1 - z} NbO ₄ : zEu ^{3 + up} to 45 mol% (z = 0.45) without generating a secondary phase, and as a result, was confirmed to increase, while the _{Y 1 - x Al x NbO 4} : Eu 3 + (0≤x <1) and _{Y 1 - x Ga x NbO 4} : Eu 3 + (0≤x <1) is x = 0.2, respectively And z = 0.1, it was confirmed that the intensity is about twice higher than YNbO ₄ : Eu ^{3 +} . This allows Y _{1 - x} Al _x NbO ₄ : Eu ^{3 +} and Y _{1 - x} Ga _x NbO ₄ : Eu ^{3 +} (0≤x <1) to be red phosphors with high emission intensity in white LEDs using near-ultraviolet chips. It is expected that it can be usefully utilized.

As described above in detail specific parts of the present invention, it is apparent to those skilled in the art that such specific descriptions are merely preferred embodiments, and thus the scope of the present invention is not limited thereto. something to do. Thus, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

FIG. 1 shows red emission intensity according to Eu concentration (z value) of Y _1-z NbO ₄ : _z Eu ³⁺ (0 <z <0.5) powder when the excitation wavelength is 397 nm and the emission wavelength is 613 nm.

Figure 2 is an excitation wavelength of 466 nm, emission wavelength 613 nm when one Y _{1 - z} NbO _4: shows a red light-emitting intensity of the Eu ^{3 +} _z (0 <z <0.5) powder of the concentration of Eu (z value).

Figure 3 is _{Y 1 - x Al x NbO 4} : it shows the excitation spectra of the Al addition amount (x) of Eu ^{3 +} (0≤x <1) powder.

4 shows the emission spectrum (excitation wavelength: 397 nm) according to the amount of Al added (x).

5 shows the emission spectrum (excitation wavelength: 466 nm) according to the amount of Al added (x).

Figure 6 is _{Y 1 - x Ga x NbO 4} : shows the excitation spectra of the Ga amount (x) of Eu ^{3 +} (0≤x <1) powder.

7 shows the emission spectrum (excitation wavelength: 397 nm) according to the Ga addition amount (x).

8 shows the emission spectrum (excitation wavelength: 466 nm) according to the amount of Ga addition (x).

Claims (10)

Red phosphor represented by the following formula (1): [Formula 1] Y _1-x M _x NbO ₄ : zEu ³⁺ In Formula 1, M is Al or Ga, x is 0 <x <1, 0 <z <0.5. The red phosphor of claim 1, wherein z in Formula 1 is 0.01 ≦ z ≦ 0.45. The red phosphor of claim 1, wherein x in Formula 1 is 0.1 ≦ x ≦ 0.4. The red phosphor of claim 3, wherein M in Formula 1 is 0.1 ≦ x ≦ 0.3. The red phosphor of claim 4, wherein when M in Formula 1 is Al, x = 0.2. The red phosphor of claim 3, wherein M in Formula 1 is 0.1 ≦ x ≦ 0.2. The method of claim 6, wherein when M in Formula 1 is Ga, x = 0. Red phosphor, characterized in that 1. The method of claim 1, wherein the red phosphor is Y ₂ O ₃ , Nb ₂ O ₅ and Eu ₂ O ₃ powder and using a LiCl as a flux to prepare a mixture step; And Ball-milling the mixture and then performing a heat treatment at 1000 to 1300 ° C. in a tube furnace of a nitrogen atmosphere; Red phosphor, which is produced by a method comprising a. In a white light emitting diode using a near ultraviolet light or a blue light emitting diode chip, A white light emitting diode, wherein the red phosphor according to any one of claims 1 to 8 is disposed on the near ultraviolet or blue light emitting diode chip. The white light emitting diode of claim 9, wherein the near ultraviolet light emitting diode chip has a wavelength of 397 ± 5 nm, and the blue light emitting diode chip has a wavelength of 466 ± 5 nm.

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