JP2000297281A - Luminous fluorescent substance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a luminous fluorescent substance that itself has the luminescence peak of >=600 nm to emit an orange color, and is efficiently excited with visible rays, for example, sunshine or a day-light color fluorescent lamp to give high afterglow of a long afterglow time without noxious element, for example, Cd in no need of addition of organic fluorescent pigment. SOLUTION: This luminous fluorescent substance mainly comprises a compound that is represented by the chemical formula: SrS.aEu.bDy where (a) and (b) are each in the range of 0.00001<=a<=0.1; 0.00001<=b<=0.1. It has the maximum peak at the wavelength of >=450 nm in the exciting spectrum of 605 nm and has the maximum emission peak wavelength of >=600 nm in the emission spectrum after irradiation with the light from a day-light color fluorescent lamp.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phosphorescent phosphor having a high afterglow luminance and a long afterglow time. More specifically, the present invention relates to a phosphorescent phosphor having an afterglow color of orange and a chemical composition formula of SrS.aEu.
The present invention relates to a novel phosphorescent phosphor mainly comprising a compound represented by bDy.

[0002]

2. Description of the Related Art Fluorescence is a phenomenon in which a substance emits light mainly in the visible region due to external stimulation (excitation by light, electricity, heat, etc.). Time that can be felt by eyes after excitation is stopped (about 0.1 second)
If this fluorescence continues, this is called phosphorescence. In addition, a phosphor having a long afterglow such that phosphorescence continues for a long time is called a phosphorescent phosphor.

[0003] As such a phosphorescent phosphor, Z
nS: Cu (yellow green light emission), CaSrS: Bi (blue light emission), CaS: Bi (purple light emission) and the like are known.
Currently, only ZnS: Cu is in practical use,
In view of danger prevention display and decorativeness, multicoloring is necessary, and a phosphorescent phosphor having a light emission color on a longer wavelength side than yellow-green is desired. Examples of conventional phosphorescent phosphors that emit light on the long wavelength side, that is, emit orange to red light include (Zn, Cd) S: Cu or ZnS: Cu mixed with an organic fluorescent pigment. However, the (Zn, Cd) S: Cu phosphorescent phosphor, which emits orange to red light, contains toxic Cd and is not used at present. ZnS mixed with an organic fluorescent pigment:
Since the Cu phosphorescent phosphor excites and emits the organic fluorescent pigment by the afterglow of ZnS: Cu to obtain red afterglow, there is a problem that the emission color is shifted due to the fading of the organic pigment. .

[0004]

SUMMARY OF THE INVENTION In view of the above-mentioned situation, the present invention does not contain a toxic element such as Cd and has a phosphorescent phosphor itself of 600 even without the addition of an organic fluorescent pigment.
A new phosphorescent phosphor that has an emission peak wavelength of at least nm and emits orange light, is efficiently excited by visible light such as sunlight or daylight fluorescent light, has a high afterglow luminance, and a long afterglow time. Providing is an issue.

[0005]

Means for Solving the Problems Accordingly, as a result of intensive research on these phosphors, it is possible to solve the problem by activating strontium sulfide with divalent Eu and co-activating Dy. The present inventors have found an excellent phosphorescent phosphor and have completed the present invention.

That is, the invention according to claim 1 is mainly composed of a compound whose chemical composition is represented by SrS.aEu.bDy, wherein a and b are each 0.00001 ≦ a ≦ 0.
The phosphorescent phosphor is characterized by being in the range of 1,0.00001 ≦ b ≦ 0.1, and the invention according to claim 2 is characterized in that the phosphorescent phosphor has an emission spectrum having an emission wavelength of 605 nm.
The phosphorescent phosphor according to claim 1, which has a maximum excitation peak wavelength at 0 nm or more. The invention according to claim 3, wherein the emission spectrum after irradiation with visible light is 600 nm.
3. The light emitting device according to claim 1, which has a maximum emission peak wavelength.
It is a luminous phosphor of the description.

SrS is a host crystal of the phosphorescent phosphor of the present invention, and by activating Eu, phosphor becomes a phosphor having a broad emission peak wavelength. It should be noted that although it has a slight afterglow property as it is, by further co-activating Eu with Dy, the afterglow luminance and the afterglow time are significantly increased, and the light in the visible region including a wavelength of 450 nm or more is also included. Thus, the phosphorescent light is easily excited, the light absorption efficiency is improved, and a phosphorescent phosphor of orange emission having a maximum emission peak wavelength at 600 nm or more can be obtained.

In the phosphorescent phosphor of the present invention, a indicates the concentration of Eu as an activator, and 0.00001 ≦ a
It must be in the range of ≦ 0.1. a <0.0000
In the case of 1, light absorption is deteriorated and a sufficient afterglow luminance cannot be obtained. Conversely, in the case of a> 0.1, concentration quenching occurs, and the afterglow luminance decreases.

B indicates the concentration of Dy which is a coactivator, and must be in the range of 0.00001 ≦ b ≦ 0.1. When b <0.00001, the effect of increasing the afterglow luminance and the afterglow time is poor. Conversely, when b> 0.1, the afterglow luminance gradually decreases.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The raw material of the phosphorescent phosphor of the present invention comprises:
Oxides, carbonates, phosphates, nitrates, sulfates, sulfides,
Sulfur or the like can be used. After weighing these raw materials in a predetermined amount and sufficiently mixing them in a ball mill or the like, the raw materials are placed in a quartz crucible and placed in a reducing atmosphere such as hydrogen gas at 800 to 1 wt.
Bake at 300 ° C for 1 to 12 hours. The firing atmosphere is not limited to a reducing atmosphere, and may be an oxidizing atmosphere such as in the air as long as Eu is divalent after firing.

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

[0012]

EXAMPLES (Example 1) SrCO ₃ 3.829 g (NH ₄ ) ₂ SO ₄ 2.056 g Eu ₂ O ₃ 0.018g Dy ₂ O ₃ 0.097 g The raw materials having the above composition were sufficiently mixed, placed in a quartz crucible, and fired at 1100 ° C. for 2 hours in a mixed gas stream of 97% N ₂ + 3% H ₂ . The obtained compound is converted to X by CuKα radiation.
As a result of the RD measurement, an X-ray diffraction diagram as shown in FIG. 1 was obtained. From this figure, it was found that the phosphorescent phosphor was composed of a crystal mainly composed of SrS.

FIG. 2 shows an emission spectrum of the phosphorescent phosphor excited by the light of a daylight fluorescent lamp, and one minute after stopping the irradiation. The measurement was performed using a spectrofluorometer (FP-750, JASCO Corporation). The emission peak wavelength is 605
nm, and orange light emission was visually observed. FIG. 3 shows an excitation spectrum measured at an emission wavelength of 605 nm. Here, the excitation spectrum of Comparative Example A described later is also shown. From this spectrum, it can be seen that in both Example 1 and Comparative Example A, the excitation wavelength range is wide in the visible region, and it is easily excited by light such as sunlight or a fluorescent lamp. However, in Example 1, that is, when Dy was added, the intensity of the entire excitation spectrum was increased, and it was particularly remarkable at 450 to 520 nm. From this, it can be said that adding Dy to SrS: Eu makes it easier to absorb visible light.

(Comparative Example A) SrCO ₃ 3.892 g (NH ₄ ) ₂ SO ₄ 2.090 g Eu ₂ O ₃ 0.018 g The raw materials having the above composition were sufficiently mixed, placed in a quartz crucible, and fired at 1000 ° C. for 2 hours in a mixed gas stream of 97% N ₂ + 3% H ₂ . The obtained compound was used as Comparative Example A.

The luminous phosphors of Example 1 and Comparative Example A were excited with a daylight fluorescent lamp at 200 lx for 4 minutes, and the change with time of the afterglow luminance immediately after the excitation was stopped is shown in FIG. The measurement was performed using a luminance meter (LS-100, Minolta Co., Ltd.). From this figure, it can be seen that the phosphorescent phosphor of Example 1 has higher luminance and longer afterglow time than Comparative Example A. That is,
It can be said that the co-activation of Eu-activated SrS with Dy increases the afterglow luminance and the afterglow time.

In the same manner as in Example 1, Examples 2 to 5 were produced in the same manner as in Example 1. These compositions are shown in Table 1.
Shown in The composition is the compounding raw material composition before firing. Each phosphorescent phosphor was excited at 200 lx for 4 minutes using a daylight fluorescent lamp, and the afterglow luminance immediately after the excitation was stopped was measured with a luminance meter. The relative afterglow luminance shown in Table 1 is a relative value in which the afterglow luminance of Comparative Example A is set to 100 in the afterglow luminance one minute after the excitation is stopped.

[0017]

[Table 1]

[0018]

The present invention is configured as described above and has the following effects. The phosphorescent phosphor according to the present invention does not contain a toxic element such as Cd, and the phosphorescent phosphor itself has an emission peak wavelength of 600 nm or more even without the addition of an organic fluorescent pigment, and has an afterglow luminance. It emits high orange light and has long persistence. In addition, since it has an excitation spectrum peak in the visible light region, particularly in the range of 450 to 520 nm, it can be efficiently excited by a daylight fluorescent lamp.

[Brief description of the drawings]

FIG. 1 is an X-ray diffraction diagram of Example 1.

FIG. 2 is an emission spectrum one minute after stopping light excitation in Example 1.

FIG. 3 is an excitation spectrum at an emission wavelength of 605 nm in Example 1.

FIG. 4 is a graph showing a change with time in the afterglow luminance of Example 1 and Comparative Example A.

Claims (3)

[Claims] 1. A compound mainly represented by a chemical composition represented by SrS.aEu.bDy, wherein a and b are each 0.00
A luminous phosphor, wherein 001 ≦ a ≦ 0.1 and 0.00001 ≦ b ≦ 0.1. 2. An excitation spectrum having an emission wavelength of 605 nm, having a maximum excitation peak wavelength at 450 nm or more.
The phosphorescent phosphor according to claim 1. 3. It has a maximum emission peak wavelength at 600 nm or more in an emission spectrum after irradiation with visible light.
The phosphorescent phosphor according to claim 1.