KR100436706B1 - Blue-emitting phosphor - Google Patents

Abstract

The present invention provides a plasma display panel and a lamp employing a blue light emitting phosphor represented by the formula (1) and a phosphor layer comprising the same.

{M (1) _ax M (2) _b } n (Al _1-c B _c ) ₂ O ₃ : Eu _x

Wherein M (1) is Sr, Ca or Ba, M (2) is Be or Mg, 1 ≦ n ≦ 6, 0.7 ≦ a ≦ 9.9999, 0.5 ≦ b ≦ 2.0, 10 ⁻⁴ ≦ c ≦ 0.06, 0.3 ≦ x ≦ 10 ⁻⁴ . The blue light-emitting phosphor represented by Chemical Formula 1 of the present invention has excellent color purity and luminance characteristics, and excellent oxidation resistance. In addition, the blue light emitting phosphor has excellent color rendering index characteristics, and thus may be usefully applied to a lamp such as a tricolor pump and a backlight of a liquid crystal display.

Description

Blue-emitting phosphor

The present invention relates to a blue light emitting phosphor, and more particularly, to a blue light emitting phosphor that is excellent in color purity and luminance characteristics as well as excellent in oxidation resistance.

Examples of the blue light emitting phosphor for vacuum ultraviolet excitation include BaMgAl ₁₀ O ₁₇ : Eu, BaMgAl ₁₄ O ₂₃ : Eu, CaWO ₄ : Pb, Y ₂ SiO ₄ : Eu, and the like. Among them, the barium silicate-based phosphor has a light emission peak in the 450 nm region, and BaMgAl ₁₀ O ₁₇ : Eu (II) has excellent luminance characteristics, and thus is widely used in phosphor-forming materials of plasma display panels, tricolor lamps, and liquid crystal display device backlights. It is becoming.

However, since the BaMgAl ₁₀ O ₁₇ : Eu (II) phosphor is easily oxidized, the luminance is lowered, and color coordinates are shifted due to ion shock and ultraviolet irradiation, thereby degrading color purity characteristics.

In order to solve the problems described above, the composition of the phosphor may be changed by adding a new activator component to the phosphor, adding a new activator component to the phosphor, or changing a host element, or by substituting other elements in place of Ba, Methods using lattice distortions caused by differences in ion size have been proposed (Japanese Patent Laid-Open Nos. 8-115673 and 9-272867).

Japanese Patent Laid-Open No. 8-115673 discloses Ba _1-x Eu _x MgAl ₁₀ O ₁₇ (x is 0.05 to 0.5), which is a barium magnesium aluminate-based phosphor. However, the barium magnesium aluminate-based phosphor has excellent blue color purity and luminance characteristics, but has a problem of deterioration with time when used in lamps and plasma display panels.

On the other hand, Japanese Patent Laid-Open No. 9-272867 provides a phosphor of the following structural formula.

(M ¹ _1-ax M ² _a ) n (Al _1-b B _b ) ₂ O ₃ : Eu _x X _y

Wherein M ¹ is Sr, Ca or Ba, M ² is Be, Mg, Zn or Cd, X is F, Cl Br or I, 0.7 ≦ n ≦ 2.0, 0 ≦ a ≦ 0.2, 0 ≦ b ≦ 0.2, 1 × 10 ⁻⁵ ≦ x ≦ 1 × 10 ⁻¹ . 1 × 10 ⁻⁵ ≦ y ≦ 1 × 10 ⁻¹ .

Phosphors having the structure as described above are long afterglow and light emitting peaks appear in the green-blue region. Therefore, this phosphor is suitable for lamps and the like, but does not satisfy the blue color purity required for the plasma display panel and the afterglow characteristic required for the display.

However, even when the phosphors obtained according to the method of changing the composition, crystallinity, etc. of the phosphor are used, there is still a lot of room for improvement because the luminance and color purity characteristics and the oxidation resistance do not satisfy the levels required for the plasma display panel and the lamp. .

The technical problem to be solved by the present invention is to solve the above problems, to provide a blue light emitting phosphor which is not only excellent in color purity and luminance characteristics, but also oxidation resistance is reduced degradation degree and its use.

1 is a diagram showing an excitation spectrum of a phosphor according to Example 3 of the present invention and BaEuMgAl ₁₀ O ₁₇ according to the prior art.

In order to achieve the above technical problem, the present invention provides a blue light emitting phosphor represented by the formula (1).

<Formula 1>

{M (1) _ax M (2) _b } n (Al _1-c B _c ) ₂ O ₃ : Eu _x

Wherein M (1) is Sr, Ca or Ba, M (2) is Be or Mg, 1 ≦ n ≦ 6, 0.7 ≦ a ≦ 9.9999, 0.5 ≦ b ≦ 2.0, 10 ⁻⁴ ≦ c ≦ 0.06, 0.3 ≦ x ≦ 10 ⁻⁴ .

It is preferable that said M (1) is Ba, and M (2) is Mg, It is more preferable to represent with the following structural formula especially.

Ba _0.85 Eu _0.15 Mg (Al _10-x B _x ) O ₁₇

In said formula, x is 0.01-0.05.

Another technical problem of the present invention is achieved by a plasma display panel and a lamp, wherein a phosphor layer made of the blue light emitting phosphor of Chemical Formula 1 is employed.

Most blue light emitting phosphors for plasma display panels emit light by a light source having an excitation light of 147 nm, and only the surface of the phosphor mainly contributes to light emission. Therefore, the luminous efficiency of the phosphor is very different depending on the presence or absence of surface defects.

Accordingly, in the present invention, a part of aluminum (Al) is replaced with boron (B) in a BaMgAl ₁₀ O ₁₇ : Eu (II) phosphor, which is a barium magnesium aluminate-based phosphor that is excited by a light source of about 147 nm and 254 nm, By adjusting the composition ratio of the remaining constituent elements to a predetermined range to remove the instability factor of the phosphor crystal defects to provide a blue light emitting body of the formula (1) excellent in brightness and color purity characteristics and excellent oxidation resistance. At this time, boron increases the energy band gap of BaMgAl ₁₀ O ₁₇ : Eu (II) phosphor, which has excellent color purity characteristics, and improves crystallinity of the phosphor, thereby increasing the absorption rate of excitation light as well as acting as a flux, thereby causing defects on the surface of the phosphor. It acts to reduce. This will be described in detail.

BaMgAl ₁₀ O ₁₇ : Eu (II) phosphor is generally subjected to a high temperature firing process of 1600 ° C. or above in a reducing atmosphere. AlF ₃ and MgF ₂ are used as the flux during the high temperature firing process. Among them, AlF ₃ plays a very important role in grain growth of BaMgAl ₁₀ O ₁₇ : Eu (II) phosphor.

BaMgF ₄ : Eu (II) + (17/3) Al ₂ O ₃ ↔ BaMgAl ₁₀ O ₁₇ : Eu (II) + (4/3) AlF ₃

In Reaction Scheme 1, when the reaction temperature is 1200 ° C. or more, BaMgF ₄ : Eu (II) in a liquid state starts to react with Al ₂ O ₃ to generate BaMgAl ₁₀ O ₁₇ : Eu (II) phosphor, and the maximum sintering temperature The particle size is determined accordingly and AlF ₃ is sublimed. In general, since F and O are similar in size, there is a possibility that F- is substituted at O ^2- position to cause crystal defects and a high probability of non-radiation transition. In the present invention, B ₂ O ₃ is added as a flux. The aim was to improve the crystallinity and oxidation resistance by removing the instability factor of crystal defects.

<Formula 1>

{M (1) _ax M (2) _b } n (Al _1-c B _c ) ₂ O ₃ : Eu _x

Wherein M (1) is Sr, Ca or Ba, M (2) is Be or Mg, 1 ≦ n ≦ 6, 0.7 ≦ a ≦ 9.9999, 0.5 ≦ b ≦ 2.0, 10 ⁻⁴ ≦ c ≦ 0.06, 0.3 ≦ x ≦ 10 ⁻⁴ .

In particular, it is preferable that M (1) is Ba and M (2) is Mg. Especially, it is preferable to represent with the following structural formula.

Ba _0.85 Eu _0.15 Mg (Al _10-x B _x ) O ₁₇

In the formula, x is 0.01 to 0.05.

M (1) is Ba and M (2) is Mg.

First, Ba compound, Eu compound, Al compound, Mg compound, and B compound are mixed. In this case, the mixing molar ratio of the four components is 0.85 to 1 mol for Ba compounds, 0.075 to 0.09 mol for Eu compounds, 9.8 to 10 mol for Al compounds, 0.2 to 0.05 mol for Mg compounds and 0.1 to 0.01 mol for B compounds. to be. BaCO ₃ , BaO, BaCl ₂ , Ba (NO ₃ ) ₂ or Ba [OCH (CH ₃ ) ₂ ] ₂ is used as the Ba compound, and Eu ₂ O ₃ , EuCl ₃ , etc. is used as the Eu compound. , Mg compound using MgCO ₃ Mg (OH) _{2 ·} 5H ₂ O, Al ₂ O ₃ or Al (OH) ₃ is used as Al compound, B ₂ O ₃ or H ₃ BO as a B compound _{Use 3}

The mixture is sufficiently mixed and then calcined at 1300 to 1700 ° C, preferably 1400 to 1500 ° C for 2 to 6 hours in a reducing gas atmosphere. Here, the reducing gas is not particularly limited, but a nitrogen / hydrogen mixed gas of 95: 5 volume ratio is used.

In the firing process, when the firing temperature is out of the above range, the luminance characteristic of the finally obtained phosphor is poor, which is not preferable.

Thereafter, the calcined phosphor may be washed with 1-20% aqueous hydrochloric acid solution, and then washed with water and dried to obtain a blue light-emitting phosphor of Chemical Formula 1. The reason for the process of washing with an aqueous hydrochloric acid solution is to remove unreacted substances or defects remaining on the surface of the phosphor. And the drying temperature after washing with water is preferably 50 to 120 ℃. At this time, when the drying temperature exceeds 120 ° C, aggregation between the phosphor particles occurs, which is not preferable.

The blue light emitting body obtained by the above method not only has excellent color purity and luminance characteristics, but also excellent oxidation resistance, and when applied to the plasma display panel, image quality characteristics can be improved. In addition, since the color rendering index is large, it can be usefully used for a lamp such as a tricolor lamp and a backlight of a liquid crystal display device.

Hereinafter, the present invention will be described with reference to the following examples, but the present invention is not limited only to the following examples.

Example 1

A mixture of 0.85 mol of BaCO ₃ , ₁ mol of MgCO ₃ Mg (OH) ₂ 5H ₂ O, 9.99 mol of α-Al ₂ O ₃ , 0.15 mol of Eu ₂ O ₃ and 0.01 mol of B ₂ O _{3 having a} purity of 99.9% was thoroughly mixed. .

The mixture was placed in an alumina tube and calcined at about 1500 ° C. for 4 hours under a 95: 5 volumetric nitrogen / hydrogen mixed gas atmosphere.

After the calcination was completed, the resultant was washed with 10% HNO ₃ aqueous solution and then washed several times with distilled water. The phosphor washed with distilled water was dried at 100 ° C. for 10 hours to obtain Ba _0.85 Eu _0.15 Mg (Al _9.99 B _0.01 ) O ₁₇ .

Example 2-5

A corresponding phosphor was prepared in the same manner as in Example 1 except that the content of B ₂ O ₃ was 0.03, 0.05, 0.07, and 0.09 mol instead of 0.01 mol.

Example 6-7

A corresponding phosphor was prepared in the same manner as in Example 1, except that the content of B ₂ O ₃ was 0.1 and 0.2 mol instead of 0.01 mol.

Comparative Example 1

Ba _0.85 Eu _0.15 MgAl ₁₀ O ₁₇ was obtained in the same manner as in Example 1 except that B ₂ O ₃ was not used at all.

The phosphors obtained according to Example 1-5 and Comparative Example 1 were excited with vacuum ultraviolet rays of 254 nm to measure relative emission luminance and color coordinate characteristics of the phosphors. At this time, commercially available BaEuMgAl ₁₀ O ₁₇ was used as a reference phosphor for indicating the relative luminance of the phosphor.

Table 1 is a graph showing the relative emission luminance, color coordinates and maximum emission peak characteristics of the phosphor according to Example 1-5.

For reference, the color coordinate requirement standards of the display NTSC (National Television Standard Committee) are: x≤0.15, y≤0.08.

From Table 1, it can be seen that the phosphors according to Examples 1-5 have improved luminance and color purity characteristics compared to BaEuMgAl ₁₀ O ₁₇ and Comparative Example 1.

1 shows an excitation spectrum of a phosphor according to Example 3 and BaEuMgAl ₁₀ O ₁₇ .

Referring to FIG. 1, it can be seen that the luminous efficiency of the phosphor of Example 3 is improved compared to BaEuMgAl ₁₀ O ₁₇ in an excitation wavelength region of 180 nm or more.

In addition, the phosphor prepared according to Example 6-7 was excited by vacuum ultraviolet ray at 254 nm, and the relative emission luminance, color coordinate, and maximum emission peak of the phosphor were measured and shown in Table 2 below.

From Table 2, the phosphor obtained according to Example 6-7 has a maximum emission peak closer to 460 nm compared with BaEuMgAl ₁₀ O ₁₇ and the spectrum distribution is formed around this center wavelength, thereby increasing the color rendering index. It has been found that the relative light emission luminance increases markedly. Thus, the phosphors of Examples 6-7 are very suitable for lamps. Here, the color rendering index is an important lamp characteristic that depends on the spectral energy distribution of light emission. The color rendering index is a value determined by irradiating a lamp and a blackbody emitter as a light source, and comparing a series of color points of a color to be tested under both conditions. If the light is emitted from both light sources, the color rendering index is set to 100 when the color points are the same.

On the other hand, the oxidation resistance of the phosphor prepared according to Example 3-5 and Comparative Example 1 was evaluated. Here, the oxidation resistance is evaluated by measuring the percentage value of the luminous luminance (L ₆₀₀ ) after the heat treatment of the phosphor at 600 ° C. for 1 hour, and after the annealing luminance (L ₀ ).

As a result, L ₆₀₀ / L ₀ of the phosphors according to Examples 3-5 was 56.3. As 67.0 and 79.6%, it was found that the degree of lowering of luminance was reduced compared to that of BaEuMgAl ₁₀ O ₁₇ and Comparative Example 1 (L ₆₀₀ / L ₀ is 53.4%), thereby showing better oxidation resistance. In addition, it was also found that as the boron content gradually increased, oxidation resistance was further improved.

As described above, the blue light-emitting phosphor represented by Chemical Formula 1 of the present invention has excellent color purity and luminance characteristics, and excellent oxidation resistance. In addition, the blue light emitting phosphor has excellent color rendering index characteristics, and thus may be usefully applied to a lamp such as a tricolor pump and a backlight of a liquid crystal display.

Claims (5)

A blue light emitting phosphor for a plasma display panel, which is represented by the following structural formula. Ba _0.85 Eu _0.15 Mg (Al _10-x B _x ) O ₁₇ In said formula, x is 0.01-0.05. delete delete A plasma display panel comprising a phosphor layer made of the blue light emitting phosphor according to claim 1. delete