JPH02170888A - Production of blue light-generating fluorescent material - Google Patents

Abstract

PURPOSE:To provide the subject divalent Eu-added fluorescent material generating a highly bright light under an UV light-excited state and having a small temperature dependency by adding an ammonium halide to a material mixture, subjecting the mixture to the first calcination process in air and subsequently subjecting to the second calcination process in a reducing atmosphere. CONSTITUTION:Compounds readily converted into BaO, MgO, Eu2O3 and Al2O3 at high temperature are mixed with each other and the mixture is further mixed with an ammonium halide represented by NH4X (X is F, Cl, Br or I) in an amount of 0.1-10.0wt.% and subsequently subjected to the first calcination process at 1200-1400 deg.C in air. The mixture is subjected to the second calcination process at 1400-1700 deg.C in a reducing atmosphere to provide a blue light- generating Eu-added aluminate fluorescent material represented by the formula (x is 0.1-0.5; y is 0.1-0.8; z is 0.03-0.10; x+y+z=1; a is 1.5-4.5).

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) This invention relates to a method for producing a blue-emitting phosphor activated with divalent europium.

(Prior Art) In recent years, demands for higher color rendering and higher output have been increasing for fluorescent lamps for general lighting, and as a means of satisfying these demands, blue light, which has a relatively narrow band emission spectrum distribution, There is a three-wavelength fluorescent lamp in which a fluorescent film is formed by mixing green and red light-emitting phosphors in an arbitrary ratio. Further, these fluorescent lamps themselves are becoming more compact, and as compared to conventional straight tube and annular fluorescent lamps, the load on the tube wall is greater and the temperature inside the tube is higher.

Incidentally, aluminate-based phosphors have been conventionally used as the blue component of three-wavelength fluorescent lamps.

Eurobium-activated aluminate phosphor [(B a E u ) Mg2Aji, a well-known blue-emitting phosphor
'+6027] (described in Japanese Patent Publication No. 52-22836) and the same europium-activated aluminate phosphor [A
O-AlzOv system (A-Znx Mg, Ca, S
rsB a s L i 2 , Rb 2 , C823
(described in Japanese Patent Publication No. 58-22495) and phosphors described in Japanese Patent Publication No. 59-43507.

However, there is room for improvement in terms of high-temperature luminance.

(Problems to be Solved by the Invention) As mentioned above, when existing blue-emitting phosphors are used in small lamps, the temperature of the phosphor layer increases, causing significant thermal deterioration of the phosphor and resulting in low luminous efficiency. Become.

The present invention was made to solve the above problems, and an object of the present invention is to provide a method for manufacturing a blue-emitting phosphor that emits light with high brightness under ultraviolet excitation and has low temperature dependence.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides for easily converting B a OsM g at high temperatures.
OsE u 20 i and a compound that becomes Af120s are mixed and fired in air at 1200-1400°C, and then the above compound is heated in a reducing atmosphere at 1400-170°C.
After secondary firing at 00℃, the general formula (Ba, Mgv Eu,)O* aA1120*
(However, 0.1≦x≦0.5.0.1≦y≦0.8.0
．． 03≦z≦0,10, X+y+Z=1, 1.5≦a≦
4,5) In the method for producing a blue-emitting phosphor to obtain a europium-activated aluminate phosphor represented by -F, Cg.

This method of producing a blue-emitting phosphor is characterized in that ammonium halide represented by at least one selected from BrS1 is added before the primary firing.

(Function) According to the present invention, the decrease in luminance at high temperatures is significantly improved.

(Example) Hereinafter, a method for manufacturing a blue-emitting phosphor according to the present invention will be described in detail with reference to the drawings.

First, the phosphor raw materials include at least one type selected from a group of barium compounds that easily become barium oxide at high temperatures, such as barium oxide, barium hydroxide, and barium carbonate, as a barium source, and magnesium oxide and water as a magnesium source. At least one member selected from the group of magnesium compounds that easily become magnesium oxide at high temperatures, such as magnesium oxide and basic magnesium carbonate, and a europium compound that easily becomes europium oxide at high temperatures, such as europium oxide and europium carbonate, as a europium source. At least one member selected from the group consisting of at least one member selected from the group consisting of aluminum compounds that easily become aluminum oxide at high temperatures, such as aluminum oxide and aluminum hydroxide, as an aluminum source, and ammonium halide, e.g., as an additive. NH4F.

At least one of NHa Cil SNH, B rSNH, I is used.

A predetermined amount of these raw materials is weighed, thoroughly ground and mixed using a ball mill or the like. This sufficiently mixed raw material mixture is placed in a heat-resistant container such as a crucible, and heated to 1200°C in the air.
to 1,400°C (firing for 2 to 3 hours).

After soaking the obtained baked product in an acid such as nitric acid for about 24 hours,
Thoroughly wash with pure water at a temperature of 80°C or higher, filter and dry.

After that, it is placed in a heat-resistant container such as a crucible again and subjected to secondary firing (4
~5 hours of baking). Grinding into the baked product made in this way,
Add processing such as washing with water.

In addition, the above additives NH4X (however, X-F, C
9% Br, at least one selected from I) is 1
Must be added before the next firing.

After the first firing, that is, before the second firing, the effect cannot be exhibited.

Furthermore, the amount of NH4X (however, X-F, Cρ, B', at least 18 selected from summer) added is set in the range of 0.1 to 10.0% by weight based on the total weight of the compound. The reason is explained below.

That is, if the amount of NH4X added is less than 0.1% by weight,
It has no effect on the temperature dependence of luminescence brightness, which is the problem to be solved by this invention, and the 10.0ffi! 96
If the amount is too large, a phase other than the desired substance will appear, making it impossible to obtain a stable phosphor, resulting in a decrease in luminance. In the range of 0.1% by weight to 1000% by weight, NH4I stabilizes the crystal structure of the host and can exhibit high luminance even at relatively high temperatures (see Figure 1).

Now, let's explain by giving specific numbers.

Example-1 B a C03---78,9g Mg (OH)2...32.1gEu
2Q, ・・・・・・・・・ 8.8gAa12o
3 ・・・・・・・・・255.0gNH4F
-----------18,7g (5,0ffiff
i%) The above raw materials were weighed, thoroughly ground and mixed using a ball mill. This raw material mixture was placed in a crucible and calcined in air at 1350°C for 3 hours. The obtained baked product was soaked in nitric acid for 24 hours, thoroughly washed with 85°C pure water, filtered and dried.

Thereafter, it was placed in the crucible again and fired at 1650° C. for 4 hours in an atmosphere of 3% hydrogen and 97% nitrogen. The baked product thus produced is subjected to treatments such as pulverization and washing with water (B a O,
40M go, ssE u o, os) 0 ・2.
5A120. A divalent europium-activated aluminate phosphor represented by the formula was obtained.

When the luminance at room temperature of the phosphor obtained without adding NH and F is set as 100, the luminance at 250°C of the above phosphor is 8o, and the luminance at room temperature of the phosphor obtained in this example is 100. The luminance at 100° and the luminance at 250°C are 9
It was 5.

Example-2 B a CO3-=...” 7g, 9gMg (OH
) 2・・・・・・・・・ 32.1gE u 203
- ・” ・” 17.8gA D 203
---255.0gN H4F -----...=
-3.7g (1.0% by weight) The above raw material was treated in the same manner as in Example-1, and the luminance of the obtained phosphor was measured.The luminance at room temperature was 100. The brightness was 92.

Example-3 B a C03-・=・” 78.9gMg (O
H) 2...32.1gEu2Q,
・・・・・・・・・ 8.8gA II 203
---255.0gN H4F ------
---0.4g <0.1fff1%) The above raw material was treated in the same manner as in Example 1, and the luminance of the obtained phosphor was measured. The luminance at room temperature was 100.250"C.
The luminance was 83.

Example-4 B a C03'' --7g, 9g Mg (OH)z...32.1gEu
2O,...8.8gA II 20
s---255,0gNH,F---
-37.4g (10.0% by weight) The above raw material was treated in the same manner as in Example-1, and what was the luminance of the phosphor obtained?
#1 After setting, the emission brightness at room temperature is 100,250
The luminance at 'C was 85.

Next, as Examples-5 to Example-16, the raw material NH
Similar experiments were conducted with different amounts of 4x added, and improvements in properties were observed in all cases.

The results of Examples 1 to 16 are summarized in the following
Shown in the table.

However, A is the brightness at 250° C. B is the brightness at room temperature [Effects of the Invention] As explained above, according to the present invention, it is possible to obtain a blue light-emitting phosphor whose luminance decreases little at high temperatures.

[Brief explanation of the drawing]

FIG. 1 is a characteristic curve diagram showing the relationship between the amount of NH4F added and the luminance at 250°C.

Claims (1)

[Claims] At high temperatures, BaO, MgO, Eu_2O_3
, and a compound that becomes Al_2O_3, and 1
The compound is first fired at 200 to 1400°C, and then the above compound is fired secondarily at 1400 to 1700°C in a reducing atmosphere to form a compound with the general formula (Ba_xMg_yEu_z)O・aAl_2O.
_3 (However, 0.1≦x≦0.5, 0.1≦y≦0.8
, 0.03≦z≦0.10, x+y+z=1, 1.5≦
a≦4.5), in which 0.1 to 10.0% by weight of the general formula NH_4X (however, , X=F) at least one selected from Cl, Br, and I) is added before the primary firing.