KR101174608B1 - Green light emitting phosphors of Li-Al-O system and method for producing the same - Google Patents

Abstract

The present invention relates to a green phosphor comprising Li-Al-O as a mother and europium (Eu) as an activator, and a method of manufacturing the same.
The green phosphor of the present invention and a method of manufacturing the same have an absorption wavelength region in a very broad wavelength range (250 nm to 500 nm) and improve the emission intensity of the Li-Al-O-based phosphor, and have a broad emission wavelength region of 450 nm to 650 nm. Has

Description

Green light emitting phosphors of Li-Al-O system and method for producing the same

The present invention relates to a green phosphor comprising lithium aluminum oxide (Li-Al-O) as a matrix and europium (Eu) as an activator, and a method of manufacturing the same.

The present invention relates to a green phosphor and a method for manufacturing the same, wherein the lithium aluminum oxide system is used as a parent composition, and in addition to the parent element, may include silicon (Si), magnesium (Mg), scandium (Sc), and the like. Green phosphor capable of adding Pyrium (Pr), Iron (Fe), Cerium (Ce), Samarium (Sm), Cobalt (Co), etc. as a deactivator, as a main active agent, and a method for producing the same It is about.

At present, thanks to the rapid development of LED (Light Emitting Diode) chip luminescence efficiency and phosphor technology, various electronic display devices using LED have been applied.In order to improve the performance and extend the life of these devices, it is necessary to develop excellent phosphors with appropriate characteristics. It is essential.

In particular, such a phosphor should have an absorption wavelength in an appropriate region (300 nm to 500 nm) according to the field of use and the product to be effective and broadly applicable.

Meanwhile, the lithium aluminum oxide (Li-Al-O) system to be applied as a green phosphor in the present invention is known as a red phosphor emitting red light when iron (Fe) or europium (Eu) is added. [N. Suriyamurthy et.al, "Luminescence study of iron doped lithium aluminate phosphor", Materials Science Engineering A 403 (2005) 182], [X. Yang et. Al., "Synthesis and luminescence properties of a novel Eu ⁺³ doped γ-LiAlO ₂ phosphor", Materials letter 61 (2007) 4694].

1 shows a PL (Photoluminescence) spectrum of a LiAlO ₂ : Eu phosphor known as a red phosphor.

As shown in Figure 1, the absorption peak is observed at 200nm ~ 500nm, but the spectrum is not continuous, it can be seen that the typical red phosphor that the main emission peak wavelength at 615nm in the emission spectrum.

However, the previously reported LiAlO ₂ : Eu-based red phosphor has practically low luminous efficiency and thus has not been applied industrially at all.

The present invention devised in order to solve the problems of the prior art as described above is added to the activator and subactivator suitable for the composition of the Li-Al-O-based host material (luminescent intensity) of the Li-Al-O-based phosphor It is an object of the present invention to provide a green phosphor which emits green light and improves its efficiency and a method of manufacturing the same.

In addition, an object of the present invention is to provide a green phosphor having an absorption wavelength region in a very wide wavelength range (250 nm to 500 nm) and having a wide emission wavelength region over 450 nm to 650 nm and a method of manufacturing the same.

The object of the present invention is achieved by a green phosphor comprising lithium aluminum oxide (Li-Al-O) as a parent and europium (Eu) as an activator.

On the other hand, the green phosphor is Li _x Al _y O _z : wEu (Formula 1), Li _x Al _{y - m} B _m O _z : wEu (Formula 2), Li _x Al _y O _z : wEu + qD (Formula 3) , Li _x Al _{y - m} B _m O _z: may have the formula wEu qD + (formula 4), in the formula x is 1 ~ 4 1.0≤x≤2, y is 0.5≤y≤8, z is 1.2 ≤ y ≤ 13, w is the mole number of the active element, 0.01 ≤ w ≤ 1.0, B is Sc, Mg, Si, Ti or Ga as the parent substitution element, m is 0.01 ≤ m ≤ 2.0, w is the number of moles of the active agent As 0.01≤w≤1.0, D represents at least one of the additives of Sm, Pr, Fe, Ce, Co or Ce, q may be 0.01≤q≤0.5 as the mole of the surfactant.

The above object of the present invention comprises the steps of weighing a compound containing a lithium (Li), an aluminum (Al) -containing compound and an Eu-containing compound and mixing it in a solvent; Drying the mixed mixture; And it is also achieved by a green phosphor manufacturing method comprising the step of heat-treating the dried mixture in a reducing atmosphere.

Meanwhile, the method may further include plasticizing the dried mixture before the heat treatment.

On the other hand, the plasticity may be made in 400 ℃ ~ 1500 ℃, air or oxygen atmosphere.

On the other hand, the solvent may be ethanol, isopropylene alcohol, distilled water or water.

On the other hand, the heat treatment may be made at a temperature of 400 ℃ ~ 1500 ℃, 0.001torr ~ 760 torr.

On the other hand, the heat treatment may be performed in a reducing atmosphere at least one selected from the group consisting of hydrogen, carbon monoxide, methane, argon, nitrogen, methane or vacuum.

On the other hand, the drying step may be made at 80 ℃ ~ 200 ℃.

On the other hand, the heat treatment step is the heat treatment step of the first heat treatment step of heat-treating the mixture in a reducing atmosphere; Grinding the mixture; And a second heat treatment step of heat treating the pulverized mixture in a reducing atmosphere.

Therefore, the green phosphor of the present invention has an absorption wavelength region in a very wide wavelength range (250 nm to 500 nm) and a broad emission wavelength region over 450 nm to 650 nm while improving the emission intensity of the Li-Al-O-based phosphor. .

In addition, while having a matrix phase and an activator which is completely different from the conventional green phosphor composition, it is possible to realize a remarkably excellent characteristic in terms of green color purity and luminous efficiency, and the peak position of the maximum emission wavelength according to the type of the active agent and the inactive agent added. It can be used for various purposes.

1 shows a PL (Photoluminescence) spectrum of a LiAlO ₂ : Eu phosphor known as a red phosphor.
2 is a flowchart illustrating a method of manufacturing a green phosphor according to an embodiment of the present invention.
3A and 3B show an absorption spectrum and an emission spectrum of the green phosphor according to Example 1;
Figure 4 shows the emission intensity value according to the vacuum reduction heat treatment temperature of the green phosphor according to Example 1.
FIG. 5 is an XRD result of observing changes of a phase before and after vacuum reduction heat treatment of LiAlO ₂ : Eu (Eu / Li = 0.1), which is one example of the green phosphor composition. FIG.
6A and 6B show an absorption spectrum and an emission spectrum of the green phosphor according to Example 2. FIG.

The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms and the inventor may appropriately define the concept of the term in order to best describe its invention It should be construed as meaning and concept consistent with the technical idea of the present invention.

Therefore, the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. Therefore, It is to be understood that equivalents and modifications are possible.

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

2 is a flowchart illustrating a method of manufacturing a green phosphor according to an embodiment of the present invention.

After weighing the raw material is mixed in a solvent (S100).

The raw material may be an organic or inorganic compound containing lithium (Li), an aluminum (Al) -containing compound, a europium (Eu) -containing compound, a mother-substituted Sc, Mg, Si, Ti or Ga compound, a deactivator Sm, Pr, Fe, Ce, Co, or Ce compound and the like, are weighed according to the desired composition ratio.

The solvent may be selected from ethanol, isopropylene alcohol, distilled water or water.

Next, the mixed mixture is dried (S200).

The mixture may be dried in an oven (dryer) and dried at 80 ° C. to 200 ° C. for 2 to 4 hours, and may be used in a batch or continuous oven.

Next, the dried mixture (dried body) is calcined (S300).

As an example of the plasticity, the dried mixture may be placed in a high purity alumina boat and plasticized for 0.5 hours to 24 hours in a temperature of 400 ° C to 1500 ° C, air or oxygen.

On the other hand, a process of grinding the dried mixture before the plasticity may be added.

Next, the plasticized mixture (powder) is heat treated in a reducing atmosphere (S400).

That is, the plasticized mixture is placed in an alumina boat, at a temperature of 400 ° C. to 1500 ° C., a pressure of 0.001 tor to 760 tor, at least one selected from the group consisting of hydrogen, carbon monoxide, nitrogen, argon, methane or vacuum under 1 reducing atmosphere conditions. Heat treatment may be performed for a time to 24 hours.

On the other hand, before the heat treatment step may be subjected to the process of grinding the plasticized powder.

Meanwhile, the heat treatment may be performed a plurality of times. For example, the first heat treatment may be performed under the above-described heat treatment conditions, and the second heat treatment may be performed after the mixture is ground and then heat-treated under the above-described heat treatment conditions.

Of course, the second heat treatment condition may be the same as or different from the first heat treatment condition.

In the embodiment of the present invention, Li _x Al _y O _z is a basic matrix composition, and a part of the matrix composition may be replaced with other elements (Sc, Mg, Si, Ti, Ga, etc.).

In addition, it may include an active agent and a sub-active agent and may be made of a composition such as the following formula (1) -4.

In Formulas 1 to 4, x may be 1.0 ≦ x ≦ 2, y may be 0.5 ≦ y ≦ 8, and z may be in a range of 1.2 ≦ y ≦ 13.

[Formula 1]

Li _x Al _y O _z : wEu

(W in Formula 1 is 0.01≤w≤1.0 as the mole number of the activator)

[Formula 2]

Li _x Al _{y - m} B _m O _z : wEu

(In Formula 2, B is Sc, Mg, Si, Ti, or Ga as a substitution element on the mother, m is 0.01≤m≤2.0, w is 0.01≤w≤1.0 as mole of the activator)

(3)

Li _x Al _y O _z : wEu + qD

(W in formula (3) is 0.01≤w≤1.0 as the mole number of the active agent (or main active agent), D includes any one or more of Sm, Pr, Fe, Ce, Co or Ce as a negative active agent, q is 0.01≤q≤0.5 as mole of active agent

[Formula 4]

Li _x Al _{y - m} B _m O _z : wEu + qD

(In Formula 4, B is Sc, Mg, Si, Ga, or Ti as a substitution element on the mother, m is 0.01 ≦ m ≦ 2.0, w is 0.01 ≦ w ≦ 1.0 as mole of the main active agent, and D is a negative active agent). And at least one of Sm, Pr, Fe, Ce, Co, or Ce, and q is the number of moles of the inactive agent, 0.01 ≦ q ≦ 0.5).

First, as shown in FIG. 2, the raw material powder, Li ₂ CO ₃ : Al ₂ O ₃ : Eu ₂ O ₃ = 1: 1: 0.1 was weighed in a molar ratio, mixed with a solvent and dried.

 The solvent may be selected from ethanol, isopropylene alcohol, distilled water or water, and the drying may be put in an oven and dried for 2 to 4 hours at 80 ℃ ~ 200 ℃.

Subsequently, heat treatment was performed for 5 hours at 850 ° C. in a heat treatment atmosphere of general air.

The green phosphor was prepared by heat treatment at a temperature of 1100 ° C. for 10 hours while flowing hydrogen for a reducing atmosphere and maintaining the total internal pressure at 2 torr.

3A and 3B show absorption spectra and emission spectra of the green phosphor thus obtained.

As shown in FIG. 3A and FIG. 3B, it can be seen that the LiAlO ₂ : Eu phosphor, which showed red phosphor characteristics before vacuum reduction heat treatment, was changed to a green phosphor having excellent luminescence properties.

That is, Figure 3a is the absorption spectrum, it can be seen that the absorption occurs in a wide range ranging from 250nm to 470nm wavelength.

3b shows a maximum emission at 512 nm and a broad emission peak ranging from 450 nm to 600 nm.

Figure 4 shows the emission intensity value of the green phosphor according to the vacuum reduction heat treatment temperature.

As shown in Figure 4, it can be seen that the phosphor heat-treated at 1100 ℃ shows the best emission intensity value.

In addition, under all conditions, a wide range of excitation wavelengths from 250 nm to 500 nm are observed, the emission wavelength is shown in a wide range from 450 nm to 600 nm, the maximum excitation wavelength is observed at 420 nm, and the maximum emission wavelength is observed at 513 nm.

FIG. 5 is an XRD result of observing changes of a phase before and after vacuum reduction heat treatment of LiAlO ₂ : Eu (Eu / Li = 0.1), which is one example of the green phosphor composition. FIG.

(a) and (b) show the phase before vacuum heat treatment, (a) is obtained by plasticizing in an air atmosphere at 850 ° C. and (b) at higher 1200 ° C. All the phases observed after 850 ° C. It can be seen that it is synthesized with LiAlO ₂ phase.

The powder thus obtained shows conventional red phosphor characteristics. The phase change obtained in vacuum reduction heat treatment of these synthesized powders is (c), and the portion of LiAlO ₂ phase is changed to the spinel phase of LiAl ₅ O ₈ when vacuum reduction heat treatment is performed at a temperature of 1100 ° C. for 2 hours under a hydrogen atmosphere of 2torr. I can see that.

It is judged that the evaporation of the element Li occurs by vacuum reduction heat treatment, whereby a spinel phase containing less Li component is synthesized.

The LiAl ₅ O ₈ spinel phase thus synthesized by vacuum reduction heat treatment plays an important role in showing green phosphor characteristics.

First, as shown in FIG. 2, the raw material powder, Li ₂ CO ₃ : Al ₂ O ₃ : SiO ₂ : Eu ₂ O ₃ , and a molar ratio of 1: 0.8: 0.2: 0.1 and Li ₂ CO ₃ : Al ₂ O ₃ : Eu ₂ O _3: dried were weighed at a molar ratio of 0.02 were mixed in an alcohol solvent to _{Co 3 O 4 1: 1:} 0.1.

After calcination was performed by heat treatment for 5 hours at 850 ℃ in a heat treatment atmosphere of general air.

After that, the calcined powder was put into an alumina crucible and subjected to reduction heat treatment for 10 hours while maintaining the total internal pressure at 2 torr in a hydrogen reduction atmosphere in a vacuum graphite sintering furnace.

6A and 6B show an absorption spectrum and an emission spectrum of the green phosphor thus obtained.

Figure 6a shows the absorption spectrum _{LiAl 0 .8 Si 0 .2 O 2} : 0.1Eu [: an example of formula (II) Composition] and LiAlO _2: 0.1Eu + 0.02Co: 250nm with the absorption spectrum of Formula 3 an example of the composition] - Absorption occurs in a wide range up to 480 nm, with maximum absorption spectra at 397 nm and 420 nm, respectively.

Figure 6b shows the emission spectrum in each composition, it can be seen that all showing excellent green phosphor characteristics.

That is, the light emission characteristics were shown in a wide range of 420 nm to 550 nm, which is the characteristic of the excellent green phosphor, by vacuum reduction heat treatment, and the shift phenomenon occurred at the peak showing the maximum emission wavelength value by the change of composition.

That is, in the case of the composition of Formula 2, the maximum emission wavelength was increased at 505 nm by the addition of Si ions, and moved to a lower wavelength region than in the composition of Formula 1. The emission wavelength is 525nm.

By changing the elements added as described above, the maximum emission intensity value of the synthesized green phosphor can be variously changed, LED display to lighting device, LCD (Liquid Crystal Display) backlight, fluorescent lamp, PDP (Plasma Display Panel) phosphor, It can be applied to various fields such as UV lamp phosphor.

On the other hand, in the above-described embodiment, the composition of the mother was described only for LiAlO ₂ , but the present invention is not limited to LiAlO ₂ described above. For example, the same effect can be obtained also when using a composition of a spinel structure like LiAl ₅ O ₈ as a mother.

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, Various changes and modifications will be possible.

Claims (14)

delete Lithium aluminum oxide (Li-Al-O) as a parent and europium (Eu) as an activator, a green phosphor represented by the following formula (1).
[Formula 1]
Li _x Al _y O _z : wEu
(In Formula 1, x is 1.0 ≦ x ≦ 2, y is 0.5 ≦ y ≦ 8, z is 1.2 ≦ y ≦ 13, and w is 0.01 ≦ w ≦ 1.0 as the number of moles of the activator).
Lithium aluminum oxide (Li-Al-O) as a parent and europium (Eu) as an activator, a green phosphor represented by the following formula (2).
(2)
Li _x Al _ym B _m O _z : wEu
In Formula 2, x is 1.0 ≦ x ≦ 2, y is 0.5 ≦ y ≦ 8, z is 1.2 ≦ y ≦ 13, B is Sc, Mg, Si, Ti, or Ga as a substitution element on the mother, m 0.01 ≤ m ≤ 2.0, w is the number of moles of the active agent 0.01 ≤ w ≤ 1.0)
Lithium aluminum oxide (Li-Al-O) as a parent and europium (Eu) as an activator,
A green phosphor further comprising a deactivator of any one or more of Sm, Pr, Fe, Ce, Co or Ce.
The method of claim 4, wherein
The green phosphor is a green phosphor represented by the following formula (3).
(3)
Li _x Al _y O _z : wEu + qD
In Formula 3, x is 1.0 ≦ x ≦ 2, y is 0.5 ≦ y ≦ 8, and z is 1.2 ≦ y ≦ 13, w is the mole number of the main active agent, 0.01 ≦ w ≦ 1.0, and D is the negative active agent. And q is the number of moles of the inactive agent, 0.01≤q≤0.5)
The method of claim 4, wherein
The green phosphor is a green phosphor represented by the following formula (4).
[Chemical Formula 4]
Li _x Al _{y - m} B _m O _z : wEu + qD
In Formula 4, x is 1.0 ≦ x ≦ 2, y is 0.5 ≦ y ≦ 8, and z is 1.2 ≦ y ≦ 13, B is Sc, Mg, Si, Ga, or Ti as a substitution element on the mother, m Is 0.01≤m≤2.0, w is 0.01≤w≤1.0 as mole of the main active agent, D is a deactivator and q is 0.01≤q≤0.5 as mole of the deactivator)
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