KR950011225B1 - Green emitting luminescent material - Google Patents

Abstract

a general expression of (La1-x-y-a-bCexTbySmaTmb)Mgcp(AldBe)2qO3, wherein 0.1 <= x <= 0.8, 0.05 <= y <= 0.5, 0.00005 <= a <= 0.05, 0.00005 <= b <= 0.05, 0.5 <= c <= 3, 5.5 <= p <= 22, 0.9 <= d <= 1, 0 <= e <= 0.1, and q = 1/2 + c/3 + p(d + e)s.

Description

Green Light Emitting Phosphor for Fluorescent Lamps

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a green light emitting phosphor for fluorescent lamps, and more particularly, to a green light emitting phosphor for fluorescent lamps, in which the luminous intensity of the phosphor is increased and the luminous flux maintenance rate is improved.

In general, the fluorescent lamp phosphor should absorb 254nm Hg resonance line and emit light efficiently. Recently, the development of a new phosphor having excellent luminous efficiency is required according to the miniaturization of the glass tube and the development of the bulb type fluorescent lamp.

Calcium halophosphate phosphors, such as Ca ₁₀ (PO ₄ ) ₆ (F, Cl) ₂ : Sb, Mn, are generally used for lighting phosphors, but recently, a technique using a mixture of rare earth phosphors of red, green, and blue has been put to practical use. It is slightly expensive, but it shows high color rendering and contributes to high efficiency. For example, as a blue light emitting phosphor, europium-activated barium magnesium aluminate phosphor (BaMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ ), and as a green light emitting phosphor, cerium and terbium-activated magnesium aluminate phosphor {(Ce, Tb) MgAl ₁₁ O ₁₉ }, As the red light-emitting phosphor, europium-activated yttrium phosphor (Y ₂ O ₃ : Eu ³⁺ ) is mixed to reproduce white color.

Since the specific gravity of the green light-emitting phosphor in the phosphor used in the high color rendering fluorescent lamp is absolute, it is possible to manufacture a lamp having a higher luminous efficiency by improving the green phosphor. Therefore, many researches have been conducted on green light emitting phosphors. Currently used green light emitting phosphors include LaPO ₄ : Ce, Tb, La ₂ O ₃ .0.9P ₂ O ₅ .0.2SiO ₂ : Ce, Tb, Y ₂ SiO ₅ : Ce, Tb and (Ce, Tb) MgAl ₁₁ O ₁₉ and the like.

Among the green light emitting phosphors, the (Ce, Tb) MgAl ₁₁ O ₁₉ phosphor is an aluminate phosphor and has excellent temperature characteristics at high temperature. This is disclosed in Philips Japanese Patent Application Publication No. 48-122941, which has been used in lighting fluorescent lamps since 1974 and is one of the most used phosphors. In order to improve the luminescence intensity, luminous flux retention, and overall phosphor characteristics of the phosphor, a technique in which La, B, Si, and the like are added to the phosphor has been disclosed. For example, Japanese Patent Laid-Open Publication No. 55-29943 discloses a phosphor in which the luminous flux is improved by adding B and Mn to the above-described phosphor, and Japanese Patent Laid-Open Publication No. 60-259700 adds B to the phosphor. However, these phosphors have a problem that the shape of the particles is huge and the dispersibility of the powder is poor.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a green light-emitting phosphor for a fluorescent lamp having improved light emission intensity and luminous flux retention and improved powder characteristics.

In order to achieve the above object, the present invention provides a green light-emitting phosphor represented by the following general formula.

(La _1-xyab Ce _x Tb _y Sm _a Tm _b ) Mg _cp (Al _d B _e ) ₂ qO ₃

Where 0.01≤x≤0.8, 0.05≤y≤0.5, 0.00005≤a≤0.05, 0.00005≤b≤0.05, 0.5≤c≤3, 5.5≤p≤22, 0.9≤d≤1, 0≤e≤0.1 and to be.

The green light-emitting phosphor of the present invention comprises a mixture containing aluminum (Al), magnesium (Mg), cerium (Ce), terbium (Tb), samarium (Sm) and tolium (Tm) It is prepared through a process of mixing and sintering the calcined product obtained by primary firing in a H ₂ 5% + N ₂ 95% gas atmosphere, followed by secondary firing in a neutral atmosphere.

The raw material mixture may further include at least one of a lanthanum (La) compound and a boron (B) compound.

In the present invention, Sm and Tm added to the conventional (Ce, Tb) MgAl ₁₁ O phosphor are easily reacted with Ce and Tb (in some cases, even La), and can be co-substituted with them.

The reason for limiting the addition ratios of Sm and Tm as in the above formula is that when these ratios (a and b) are smaller than 0.00005, it is difficult to obtain a change in fluorescence characteristics due to their addition. Because it decreases.

The reason why the addition ratio of B is limited as in the above formula is that when these ratio values (e) are larger than 0.1, the phosphor sample obtained thereafter becomes too hard to obtain a phosphor having good particle characteristics. If it is out of the range, the fluorescence property is remarkably deteriorated, so that when included in the phosphor of the present invention should be within the above range.

Hereinafter, a method of manufacturing a green light emitting phosphor according to the present invention will be described in detail with reference to Examples.

Example 1

0.55 mol of aluminum oxide (Al ₂ O ₃ ), 0.1 mol of magnesium oxide (MgO), 0.06 mol of cerium oxide (CeO ₂ ), 0.0075 mol of terbium oxide (Tb ₄ O ₇ ), 0.0025 mol of samarium oxide (Sm ₂ O ₃ ), and 0.0025 mol of thulium (Tm ₂ O ₃ ) and 0.03 mol of LiF as a flux are mixed uniformly.

H ₂ 5% + N ₂ First firing at 1500 ° C. under a gas atmosphere for 2 hours. The calcined product was washed with warm water at 80-90 ° C., passed through a ball mill and a drying process, and then calcined at 1300 ° C. for 3 hours under N ₂ gas atmosphere to obtain (Ce _0.6 Tb _0.3 Sm _0.05 Tm _0.05 ) .MgAl ₁₁ O ₁₉ phosphor was prepared.

Example 2

The method of Example 1 was carried out in the same manner as in Example 1, except that (La _0.5 Ce _0.3 Tb _0.16 Sm _0.02 Tm _0.02 ) .MgAl ₁₁ O ₁₉ phosphor was prepared according to the present invention.

0.55 mol of aluminum oxide (Al ₂ O ₃ )

0.1 mol of magnesium oxide (MgO)

Lanthanum oxide (La ₂ O ₃ ) 0.025 mol

Cerium oxide (CeO ₂ ) 0.03 mol

Terbium oxide (Tb ₄ O ₇ ) 0.004 mol

Samarium oxide (Sm ₂ O ₃ ) 0.001 mol

Thulium oxide (Tm ₂ O ₃ ) 0.001 mol

Example 3

Performed in the same manner as in Example 2, but the addition amount of Sm ₂ O ₃ and Tm ₂ O ₃ to 0.00005 mol and 0.0005 mol, respectively (La _0.5 Ce _0.3 Tb _0.189 Sm _0.001 Tm _0.01 ) .MgAl ₁₁ O ₁₉ Prepare phosphor.

Example 4

Perform the same method as in Example 3 except that the amount of Al ₂ O ₃ is 0.53 mol, and 0.02 mol of boron oxide (B ₂ O ₃ ) is added (La _0.5 Ce _0.3 Tb _0.189 Sm _0.001 Tm _0.01 ) .Mg (Al _{10.6 Prepare a} B _0.4 ) O ₁₉ phosphor.

Example 5

In the same manner as in Example 1, but using a kind and the amount of addition of the starting compound (La _0.3 Ce _0.4 Tb _0.2 Sm _0.05 Tm _0.05 ). Mg (Al ₁₄ B _0.01 ) O _23.515 phosphor is prepared.

0.7 mol of aluminum oxide (Al ₂ O ₃ )

0.1 mol of magnesium oxide (MgO)

Lanthanum oxide (La ₂ O ₃ ) 0.015 mol

Cerium Oxide (CeO ₂ ) 0.04 mol

Terbium oxide (Tb ₄ O ₇ ) 0.005 mol

Samarium oxide (Sm ₂ O ₃ ) 0.0025 mol

Thulium oxide (Tm ₂ O ₃ ) 0.0025 mol

Boron oxide (B ₂ O ₃ ) 0.0005 mol

Example 6

In the same manner as in Example 5, the amount of Al ₂ O ₃ to 1.0 mol, the amount of B ₂ O ₃ to 0.00025 mol (La _0.3 Ce _0.4 Tb _0.2 Sm _0.05 Tm _0.05 ) .Mg (Al ₂₀ B _0.005 ) _{Prepare a 32.5075} phosphor.

Example 7

In the same manner as in Example 5, MgO was added in an amount of 0.05 mol (La _0.3 Ce _0.4 Tb _0.2 Sm _0.05 Tm _0.05 ) _{.Mg 0.5} (Al ₁₄ B _0.01 ) O _23.015 phosphor was prepared.

Example 8

In the same manner as in Example 1, but using the type and amount of the starting compound (La _0.7 Ce _0.2 Tb _0.0989 Sm _0.0001 Tm _0.001 ). Mg ₂ Al ₂₂ O _36.5 phosphor was prepared.

1.1 mol of aluminum oxide (Al ₂ O ₃ )

0.2 mol of magnesium oxide (MgO)

Lanthanum oxide (La ₂ O ₃ ) 0.035 mol

Cerium Oxide (CeO ₂ ) 0.02 mol

Terbium oxide (Tb ₄ O ₇ ) 0.00247 mol

Samarium oxide (Sm ₂ O ₃ ) 0.000005 mol

Thulium oxide (Tm ₂ O ₃ ) 0.000005 mol

Table 1 shows the luminance characteristics of the phosphors of the present invention prepared through the above Examples based on the (Ce, Tb) MgAl ₁₁ O ₁₉ phosphors.

As shown in Table 1, the phosphor prepared according to the method of the present invention has an initial luminance improved to a level of up to 10% over the conventional (Ce, Tb) MgAl ₁₁ O ₁₉ phosphor, and the luminous flux retention is about 100 hours after comparison. The effect is improved by 5%.

TABLE 1

In conclusion, it can be seen that the phosphor of the present invention has excellent phosphor characteristics as a phosphor obtained by simultaneously including Sm and Tm in a conventional (Ce, Tb) MgAl ₁₁ O ₁₉ -based phosphor.

Claims (1)

A green light emitting phosphor for a fluorescent lamp represented by the following general formula. (La _1-xyab Ce _x Tb _y Sm _a Tm _b ) Mg _cp (Al _d B _e ) ₂ qO ₃ Where 0.1≤x≤0.8, 0.05≤y≤0.5, 0.00005≤a≤0.05, 0.00005≤b≤0.05, 0.5≤c≤3, 5.5≤p≤22, 0.9≤d≤1, 0≤e≤0.1 and to be.