JPH1077470A - Phosphor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a green emitting phosphor excellent in temperature characteristics by employing a specified composition. SOLUTION: This phosphor is represented by the general formula (Ce,Tb)2 O3 .xMgO.yAl2 O2 ,.pA2 O3 .qBO, wherein 1<=x <=3; 8 <=14; 0<p+q<=0.5; A stands for at least one element selected from Ga, Tl and Th; and B stands for at least one element selected from Ca and Zn. This phosphor undergoes little decrease in luminous intensity even at a temperature of 100 deg.C or above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phosphor, and more particularly, to a phosphor that emits green light by ultraviolet rays of low-pressure mercury discharge.

[0002]

2. Description of the Related Art As a white fluorescent lamp for general lighting, a so-called three-wavelength band fluorescent lamp having high efficiency and high color rendering properties is well known. This is used for a fluorescent lamp by mixing three types of phosphors that respectively emit blue, green, and red light having a narrow emission wavelength range so as to emit white light as a whole.

As a phosphor used in this fluorescent lamp, for example, a barium magnesium aluminate phosphor (Ba) activated with divalent europium as a blue component is used.
MgAl ₁₀ O ₁₇ : Eu ²⁺ ) or strontium chlorapatite phosphor activated with divalent europium ((S
r, Ca, Ba) ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu ²⁺ ), a lanthanum phosphate phosphor activated with trivalent cerium and terbium as green components (LaPO ₄ : Ce ³⁺ , Tb ³⁺⁾ )
Or a cerium magnesium aluminate phosphor activated with trivalent terbium (CeMgAl ₁₁ O ₁₉ : T
b ³⁺ ), a yttrium oxide phosphor (Y ₂ O ₃ : Eu ³⁺ ) activated with trivalent europium as a red component, and the like are known.

[0004] For these phosphors, various approaches such as optimization of emission spectrum and improvement of luminous efficiency have been continued.

[0005] On the other hand, the shape of a fluorescent lamp is generally a straight tube shape or a ring shape, but recently, as an energy-saving light source instead of a light bulb, a compact fluorescent lamp in which the size of the lamp is made closer to the light bulb has become widespread. Has begun.

In a general straight tube type or ring type fluorescent lamp, the tube wall load for maintaining the optimum mercury vapor pressure is set so that the tube wall temperature becomes 40 to 50 ° C.
The tube wall temperature is 70 even in the high output type with a large wall load.
[° C.] or lower, and the temperature of the phosphor layer applied to the inner surface of the tube wall is 20 to 30 degrees lower than the tube wall temperature even when various conditions are considered.
[° C.] is high. Therefore, in normal use, the temperature of the phosphor layer does not exceed 100 ° C., and the temperature characteristics of the phosphor have not been considered much.

However, a compact fluorescent lamp that has recently become widespread has a larger tube wall load than a conventional straight or annular fluorescent lamp, and the tube wall temperature is 100 ° C. or more. Therefore, some of the phosphors coated on the inner surface have a higher temperature.

[0008]

When a fluorescent material used in a conventional fluorescent lamp is used in a compact fluorescent lamp having a tube wall temperature of 100 ° C. or more, after the lamp is turned on, the fluorescent lamp is turned on. As the temperature rises, problems such as a decrease in the luminous flux of the lamp and a change in the color of the lamp occur.

[0009] In particular, regarding the reduction of the lamp luminous flux, there is a problem of the temperature characteristic of the green light-emitting phosphor, which has the largest contribution to the light emission luminance of the lamp.

Accordingly, an object of the present invention is to provide a green light-emitting phosphor excellent in temperature characteristics, that is, a green light-emitting phosphor that has a small decrease in emission intensity even when the temperature of the phosphor becomes 100 [° C.] or more. And

[0011]

Means for Solving the Problems To solve the above problems, the phosphor of the present invention has a general formula of (Ce, Tb) ₂ O ₃ .x.
Indicated by _{MgO · yAl 2 O 3 · pA} 2 O 3 · qBO, respectively 1 ≦ x in the formula, y, p, q are x ≦ 3,8 ≦ y ≦ 1
4, 0 <p + q ≦ 0.5, A is Ga, T
at least one element selected from l and Th, B
Is represented by at least one element selected from Ca and Zn.

As a result, a green light-emitting phosphor excellent in temperature characteristics can be obtained.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The phosphor according to claim 1 of the present invention has a general formula of (Ce, Tb) ₂ O ₃ .xMgO.yAl ₂
O ₃ · pA ₂ O ₃ · qBO, where x, y, p,
q is 1 ≦ x ≦ 3, 8 ≦ y ≦ 14, 0 <p + q ≦
In the range of 0.5, A is at least one element selected from Ga, Tl, and Th, and B is at least one element selected from Ca and Zn.

According to this structure, at least one oxide selected from the group consisting of gallium oxide, thallium oxide, thorium oxide, calcium oxide and zinc oxide has been conventionally used.
A small amount of the cerium magnesium aluminate activated with valent terbium forms a solid solution to stabilize the phosphor crystal. For this reason, there is an effect that the luminous intensity almost equal to that at room temperature can be maintained even at a high temperature.

Here, the MgO content x is 1> x or 3 <x
In the region, the emission intensity was remarkably reduced, and it was recognized that this was not practical. Also, with respect to the amount y of Al ₂ O ₃ , no good phosphor was obtained in the region of 8> y or 14 <y for the same reason. Further, the total amount (p + q) of the elements to be dissolved in a small amount is 0.5 <(p + q).
No practical phosphor could be obtained even in the region (1) due to a decrease in emission intensity.

The phosphor according to the present invention can be obtained by the following manufacturing method.

First, a compound containing an element constituting the phosphor is used as a phosphor raw material, and the phosphor raw material is weighed so as to have the same or substantially the same composition as that of the phosphor to be obtained. At this time, additives such as a flux are added as needed.

Next, the weighed phosphor materials are sufficiently pulverized and mixed by a mortar method, a ball mill method or the like. This is filled in an alumina crucible, a boat, or the like, and fired in a reducing atmosphere at a temperature of 1100 ° C. to 1700 ° C. for several hours. The firing may be repeated two or more times as necessary.

Here, the phosphor raw material is not particularly limited, but typical examples are given below.

(1) Ce ₂ O ₃ easily at high temperatures such as cerium oxide (CeO ₂ ) or nitrates, carbonates, halides, etc.
Compound that can be changed to

(2) Terbium oxide (Tb ₄ O ₇ ) or Tb ₂ easily at high temperatures such as nitrates, carbonates, halides, etc.
Compounds which can be converted to O _3.

(3) Magnesium oxide (MgO) or MgO easily at high temperatures such as nitrates, carbonates, halides, etc.
Compound that can be changed to

(4) A is easily formed at a high temperature such as aluminum oxide (Al ₂ O ₃ ) or nitrate, hydroxide, halide, etc.
Compound that can be changed to l ₂ O ₃ .

[0024] (5) gallium oxide (Ga ₂ O ₃₎ or nitrates, carbonates, readily Ga ₂ O ₃ at high temperature, such as a halide
Compound that can be changed to

(6) Tl ₂ O ₃ easily at high temperatures such as thallium oxide (Tl ₂ O) or nitrates, carbonates, halides, etc.
Compound that can be changed to

(7) Thorium oxide (Th ₂ O ₃ ) or Th ₂ O ₃ easily at high temperature such as nitrate, carbonate, halide, etc.
Compound that can be changed to

(8) Calcium oxide (CaO) or a compound such as nitrate, carbonate, halide or the like which can be easily converted to CaO at high temperature.

(9) zinc oxide (ZnO) or nitrate,
Compounds such as carbonates and halides that can be easily converted to ZnO at high temperatures.

Further, a mixed compound such as oxalate of a mixture of cerium and terbium obtained by a coprecipitation method can be used.

The fluxing agent optionally used is usually a halide of an alkali metal or alkaline earth metal, a halide of an element constituting a phosphor or a phosphor, a carbonate, or the like, having a melting point higher than the firing temperature. A low one is used.
Although not particularly limited, typical examples of the flux include magnesium chloride, potassium iodide, aluminum fluoride, magnesium ammonium phosphate and the like.

[0031]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to specific examples.

Example 1 (Ce _0.67
Tb _0.33 ) ₂ O ₃ · 2MgO · 11Al ₂ O ₃ · 0.1Ga ₂
A phosphor having a composition formula represented by O ₃ was prepared.

Cerium oxide (Ce) was used as a phosphor material.
2.31 g of O ₂ ) and terbium oxide (Tb ₄ O ₇ )
1.23 [g], basic magnesium carbonate (3MgC
1.83 [g] of O ₃ .Mg (OH) ₂ .3H ₂ O), 11.21 [g] of aluminum oxide (Al ₂ O ₃ ), and 0.19 [gallium oxide (Ga ₂ O ₃ )] g], put in an automatic mortar and pulverize and mix well. Put this in an alumina crucible,
In an electric furnace, baking was performed for 2 hours at 1500 [° C.] in a reducing atmosphere of N ₂ : 90 volume [%] and H ₂ : 10 volume [%].

(Example 2) (Ce _0.67
Tb _0.33 ) ₂ O ₃ · 2MgO · 11Al ₂ O ₃ · 0.1Tl ₂
A phosphor having a composition formula represented by O ₃ was prepared.

Cerium oxide (Ce) is used as a phosphor raw material.
2.31 g of O ₂ ) and terbium oxide (Tb ₄ O ₇ )
1.23 [g], basic magnesium carbonate (3MgC
1.83 [g] of O ₃ · Mg (OH) ₂ · 3H ₂ O), 11.21 [g] of aluminum oxide (Al ₂ O ₃ ), and 0.42 [g] of thallium oxide (Tl ₂ O) Then, the same operation as in Example 1 was performed to obtain a phosphor.

(Example 3) (Ce _0.67
Tb _0.33 ) ₂ O ₃ .2MgO.14 Al ₂ O ₃ .0.3Th ₂
A phosphor having a composition formula represented by O ₃ was prepared.

Cerium oxide (Ce) was used as a phosphor material.
2.31 g of O ₂ ) and terbium oxide (Tb ₄ O ₇ )
1.23 [g], basic magnesium carbonate (3MgC
1.83 [g] of O ₃ .Mg (OH) ₂ .3H ₂ O), 14.27 [g] of aluminum oxide (Al ₂ O ₃ ), and 0.77 [thorium oxide (Th ₂ O ₃ )] g], and the same operation as in Example 1 was performed to obtain a phosphor.

(Example 4) (Ce _0.67
A phosphor having a composition formula of Tb _0.33 ) ₂ O ₃ .MgO.8Al ₂ O ₃ .0.5CaO was prepared.

Cerium oxide (Ce) was used as a phosphor material.
2.31 g of O ₂ ) and terbium oxide (Tb ₄ O ₇ )
1.23 [g], basic magnesium carbonate (3MgC
0.93 [g] of O ₃ .Mg (OH) ₂ .3H ₂ O), 8.15 [g] of aluminum oxide (Al ₂ O ₃ ), and 0.28 [g] of calcium oxide (CaO) Thereafter, the same operation as in Example 1 was performed to obtain a phosphor.

(Example 5) (Ce _0.7
Tb _0.3 ) ₂ O ₃ .3MgO.11Al ₂ O ₃ .05Zn
A phosphor having a composition formula represented by O was prepared.

Cerium oxide (Ce) was used as a phosphor material.
O ₂₎ and 2.41 [g], terbium oxide (Tb ₄ O ₇₎
1.12 g, magnesium carbonate (MgCO ₃ ) 2.53 g, and aluminum oxide (Al ₂ O ₃ ) 1
1.21 [g], 0.04 [g] of zinc oxide (ZnO)
Then, the same operation as in Example 1 was performed to obtain a phosphor.

(Example 6) (Ce _0.67
Tb _0.33 ) ₂ O ₃ · 2MgO · 11Al ₂ O ₃ · 0.1Ga ₂
O ₃・ 0.1Tl ₂ O ₃・ 0.1Th ₂ O ₃・ 0.1CaO ・
A phosphor having a composition formula of 0.1 ZnO was prepared.

Cerium oxide (Ce) was used as a phosphor material.
2.31 g of O ₂ ) and terbium oxide (Tb ₄ O ₇ )
1.23 [g], basic magnesium carbonate (3MgC
1.83 [g] of O ₃ .Mg (OH) ₂ .3H ₂ O), 11.21 [g] of aluminum oxide (Al ₂ O ₃ ), and 0.19 [gallium oxide (Ga ₂ O ₃ )] g], thallium oxide (Tl ₂ O) 0.42 [g], thorium oxide (Th ₂ O)
₃ ) 0.51 [g], calcium oxide (CaO) 0.06 [g], and zinc oxide (ZnO) 0.08 [g]
Then, the same operation as in Example 1 was performed to obtain a phosphor.

The phosphors obtained in the above Examples 1 to 6 and the terbium-activated cerium magnesium aluminate phosphor ((Ce _0.67 Tb _0.33 ) ₂ O _{3 .2M} ) conventionally used
gO · 11Al ₂ O ₃ ) was measured for the emission intensity by ultraviolet excitation in a temperature range from room temperature to 300 [° C.].

The above conventional phosphor at room temperature and Example 1
The relative emission intensities of the phosphors of Examples 1 to 6 are assuming that the emission intensity of a conventionally used phosphor is 100%.
Were all within the range of 98 [%] to 102 [%].

FIG. 1 shows the temperature characteristics of each phosphor.
Shown in In FIG. 1, the horizontal axis represents the temperature of the phosphor, and the vertical axis represents the relative luminous intensity when the luminous intensity of the phosphor at room temperature (25 ° C.) is 100 [%]. In FIG. 1, curve a represents the phosphor of Example 1 of the present invention, curve b represents the phosphor of Example 2 of the present invention, curve c represents the phosphor of Example 3 of the present invention, and curve d represents the phosphor of Example 3 of the present invention. The phosphor of Example 4 and the curve e show the phosphor of Example 5 of the present invention, and the curve f
Represents a phosphor of Example 6 of the present invention, and curve g represents a conventional terbium-activated cerium magnesium aluminate phosphor.

FIG. 1 clearly shows that the phosphor obtained in the example of the present invention has better temperature characteristics than the conventionally used terbium-activated cerium magnesium aluminate phosphor.

The above embodiment is merely an example for explaining the present invention, and the method of producing the phosphor is not limited to these.

[0049]

As described above, according to the present invention, the general formula (C)
_{e, Tb) 2 O 3 ·} xMgO · yAl 2 O 3 · pA 2 O 3 · q
BO, where x, y, p, and q are each 1 ≦ x
≦ 3, 8 ≦ y ≦ 14, 0 <p + q ≦ 0.5, A is at least one element selected from Ga, Tl and Th, and B is at least one element selected from Ca and Zn. According to the present invention, it is possible to obtain a phosphor excellent in temperature characteristics in which a decrease in emission intensity of the phosphor due to a rise in temperature is small. The advantageous effect described above can be obtained. For this reason, when the phosphor of the present invention is used in a fluorescent lamp, a lamp with a stable luminous flux can be obtained without decreasing the luminous flux as the tube wall temperature increases after the lamp is turned on. In addition, since the phosphor of the present invention is thermally stable, the luminous flux is less reduced even after the lamp has been turned on for a long time, and an advantageous effect can be obtained with respect to the lamp life characteristics.

[Brief description of the drawings]

FIG. 1 is a characteristic diagram showing temperature-luminance characteristics of a phosphor of the present invention and a conventional phosphor.

Claims (1)

[Claims] (1) The general formula is (Ce, Tb) ₂ O ₃ .xMgO.yAl ₂ O ₃ .pA ₂ O ₃
Wherein x, y, p, and q in the above formula are in the range of 1 ≦ x ≦ 38 ≦ y ≦ 140 0 <p + q ≦ 0.5, and A in the above formula is Ga, Tl , Th, and at least one element selected from Th, and B is represented by at least one element selected from Ca and Zn.