JPH11236560A - Ultra violet excited red fluorescent material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluorescent material emitting red light of high brightness by ultra violet excitation. SOLUTION: This fluorescent material is based on a fluoride containing boric acid, and as a fluorescent component it contains three-valent Europium (Eu<3+> ), and pref. shown by the formula: αBaF2 .βGdF3 .γB2 O3 .δEu (wherein 0.25<=α<=0.45, 0.15<=β<=0.6, 0.2<=γ<=0.4, and 0.04<=δ<=0.1).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phosphor which emits red light when excited by ultraviolet rays. More specifically, the present invention relates to a red phosphor which can be used as a red light source in PDP panels, fluorescent display tubes, fluorescent lamps and the like. Related to phosphors.

[0002]

2. Description of the Related Art PDP panels that excite phosphors by using vacuum ultraviolet rays emitted by rare gas discharge to emit light have been actively developed. The PDP panel is formed by a large number of display cells arranged in a matrix, each display cell is provided with a discharge electrode, a phosphor is applied inside the discharge electrode, and a rare gas (He-Xe, Ne- Xe). When a voltage is applied to the discharge electrode, vacuum ultraviolet rays are radiated, whereby the phosphor is excited and emits visible light. Recently, (Y, Gd)
BO ₃ : Eu, Zn ₂ SiO ₄ : M as a green light emitting phosphor
n, a full-color PDP panel using BaMgAl ₁₄ O ₂₃ : Eu or the like as a blue light emitting phosphor has been put to practical use.

[0003]

A PDP panel has a lower screen brightness than a cathode ray tube (CRT). Therefore, a high brightness phosphor is required. Conventionally, as a red light-emitting phosphor containing europium (Eu ³⁺ ) as a light-emitting component, a material obtained by blending europium with yttrium oxide or its composite oxide (Y ₂ O ₃ : Eu
_{^{3+, YVO 4: Eu 3+,}} Y (P, V) O 4: Eu 3+, Y 2 O 3 S: Eu 3+) are known. However, these are all oxide luminous bodies based on yttrium oxide, and have a problem that the luminous brightness is low. SUMMARY OF THE INVENTION The present invention provides a red phosphor having high emission luminance, which is a fluoride phosphor containing europium as a light emitting component.

[0004]

The fluoride phosphor of the present invention that emits red light contains boric acid together with trivalent europium.
Preferably, a rare earth element, particularly gadolinium, is blended together with an alkaline earth metal as a cation component so that high-luminance red light emission can be obtained.

That is, the present invention provides (1) a fluoride containing boric acid as a host, trivalent europium (Eu ³⁺ ) as a light-emitting component, and at least Gd as another cation component; The present invention relates to an ultraviolet-excited red phosphor, which generates red light when excited by ultraviolet light.

The ultraviolet-excited phosphor of the present invention specifically includes the following embodiments. (2) The content of europium is 1 mol% in terms of fluoride.
An ultraviolet-excited red phosphor having a content of not less than 10 mol% and not more than 10 mol%. (3) An ultraviolet-excited red phosphor having a boric acid content of 20 mol% to 40 mol%. (4) The content of Gd is at least 10 mol% in terms of fluoride.
An ultraviolet-excited red phosphor that is not more than 60 mol%. (5) A UV-excited red phosphor containing a rare earth element other than Gd together with Gd, and having a content of Gd and a rare earth element other than Gd of 10 mol% to 60 mol% in terms of fluoride. (6) An ultraviolet-excited red phosphor containing an alkaline earth metal element together with Gd or a rare earth element other than Gd as a cation component. (7) The alkaline earth metal element is one or more of Ca, Sr, and Ba, and the content thereof is 2 in terms of fluoride.
An ultraviolet-excited red phosphor having 0 mol% to 45 mol%. (8) The composition of the phosphor is αBaF ₂ βGdF ₃ γB
₂ O ₃ : δEu (0.25 ≦ α ≦ 0.45, 0.15 ≦ β ≦
0.6, 0.2 ≦ γ ≦ 0.4, 0.04 ≦ δ ≦ 0.1).

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to examples. The ultraviolet-excited phosphor of the present invention is a fluoride phosphor containing trivalent europium (Eu ³⁺ ) as a light-emitting component. Normal oxide-based phosphors are fired in the temperature range of 1000 to 1400 ° C. However, with this phosphor containing fluoride as the main component, the firing temperature is at most 1100 ° C, making it easy to manufacture. It is. Some phosphors using divalent europium as a light-emitting component have been conventionally known (Sr ₂ P ₂ O ₇ : Eu ²⁺ , Sr
₂ MgP ₂ O _7: Eu ^2+, etc.), and any of these emission colors blue to blue-green, does not produce a red emission. Also,
These phosphors are oxides, not fluorides. The phosphor of the present invention is a fluoride, and is a phosphor that emits red light when excited by ultraviolet light.

[0008] The content of europium is suitably 1 mol% to 10 mol% in terms of fluoride, and 4 mol%.
It is preferably at least 8 mol%. If the content of europium is less than 1 mol%, the emission luminance is not sufficient. Also, 1
If it exceeds 0 mol%, the concentration is too high and the emission luminance decreases.

When trivalent europium is used as the light emitting element, the emission wavelength is determined by the energy order of trivalent europium and is almost constant. However, the luminance of the phosphor greatly differs depending on the elements constituting the phosphor and the ratio thereof. In the present invention, Gd is contained as a cation component together with europium, so that red fluorescence having high emission luminance can be generated. Gd can be used in combination with other rare earth elements. Specifically, G
d alone, Gd and Y, Gd and La, etc. can be contained. By including a predetermined amount of Gd, the emission luminance of red light can be significantly increased.

The content of Gd is 10 mol% in terms of fluoride.
~ 60 mol% is suitable. When a rare earth element other than Gd is contained together with Gd, the total amount of Gd and the rare earth element other than Gd is 10 mol% to 60 mol% in terms of fluoride.
And the content of Gd is preferably from 20 mol% to 40 mol%. When the content of Gd is less than 10 mol% or more than 60 mol%, the emission luminance decreases.

The host of the red phosphor of the present invention may contain, as a cation component, Gd or an alkaline earth metal element together with two or more rare earth elements containing Gd.
By replacing a part of GdF ₃ with an alkaline earth metal element, higher luminance can be obtained. Alkaline earth metal element is C
One, two or more of a, Sr, and Ba are suitable, and the content thereof is suitably from 20 mol% to 45 mol in terms of fluoride. This content is less than 20 mol%,
Alternatively, when the content exceeds 45 mol%, the emission luminance decreases.

[0012] The fluoride phosphor of the present invention contains boric acid. The phosphor absorbs the irradiated ultraviolet light inside the mother,
Light emission as fluorescent color according to the energy order of light emitting elements
(Energy conversion) to emit light. Therefore, as the base material of the phosphor, a compound that easily absorbs ultraviolet rays is preferable, and a compound having a large number of oxygen is usually suitably used. The phosphor of the present invention uses the above-mentioned fluoride containing boric acid as its base. The content of boric acid is suitably from 20 mol% to 40 mol%. When the content of boric acid is out of the above range, the emission luminance is low.

From the above, the phosphor according to the present invention is:
αBaF ₂ .βGdF ₃ γB ₂ O ₃ : δEu (0.25 ≦ α ≦
0.45, 0.15 ≦ β ≦ 0.6, 0.2 ≦ γ ≦ 0.4, 0.4
A composition having a composition represented by the general formula of 04 ≦ δ ≦ 0.1) is preferable.

[0014]

EXAMPLES The present invention will be specifically described below with reference to examples. EXAMPLES AND COMPARATIVE EXAMPLES Raw material powders were blended so as to have a blending ratio (mol%) shown in Table 1 and charged in a crucible.
Bake by heating to 0 ° C for 12 hours including heating time,
This was pulverized and sieved to obtain a phosphor powder. This phosphor powder was printed on a substrate together with a binder to form a phosphor layer. About this phosphor layer, ultraviolet rays (wavelength 245 nm,
Irradiation with an ultraviolet intensity of 1.25 mW / cm ² ) was performed, and the emission luminance was measured. The emission luminance was evaluated based on the relative luminance with respect to the luminance of the reference phosphor (83 cd / m ² ). The results are shown in Table 1.

[0015]

[Table 1]

As shown in Table 1, a predetermined amount of europium
The phosphor of the present invention containing Gd and boric acid together with (Eu ³⁺ ) can emit red light with high luminance. Those containing an alkaline earth metal element together with Gd have high emission luminance (Sample Nos. 1, 3, 6, 7, 10, 11, 13, 14). On the other hand, europium
With a content of (Eu ³⁺ ) exceeding 10 mol% (Sample No. 2)
Has decreased luminance. In addition, those having an alkaline earth metal content of more than 45 mol% (Sample No. 4), those having a boric acid content of about 10 mol% (Sample No. 5), Y instead of Gd
(Sample No. 8), those using La instead of Gd (Sample No. 9), and those having a Gd content of less than 10 mol% (Sample No. 12) all have low emission luminance. .

[0017]

As described above, the phosphor of the present invention emits red light when excited by ultraviolet light, and has a high emission luminance. Therefore, it can be suitably used as a red light source such as a PDP panel, a fluorescent display tube, and a fluorescent lamp.

Claims (8)

[Claims] Claims: 1. A fluoride containing boric acid as a base,
Contains trivalent europium (Eu ³⁺ ) as a light emitting component,
An ultraviolet-excited red phosphor comprising at least Gd as another cation component and generating red light by excitation of ultraviolet light. 2. The ultraviolet-excited red phosphor according to claim 1, wherein the content of europium is from 1 mol% to 10 mol% in terms of fluoride. 3. A boric acid content of not less than 20 mol% to 40 mol%.
The ultraviolet-excited red phosphor according to claim 1 or 2 in an amount of not more than mol%. 4. The ultraviolet-excited red phosphor according to claim 1, wherein the content of Gd is from 10 mol% to 60 mol% in terms of fluoride. 5. The method according to claim 1, further comprising a rare earth element other than Gd together with Gd, wherein the content of Gd and the rare earth element other than Gd is from 10 mol% to 60 mol% in terms of fluoride.
5. The ultraviolet-excited red phosphor according to any one of 4. 6. The ultraviolet-excited red phosphor according to claim 1, which contains an alkaline earth metal element together with Gd or a rare earth element other than Gd as a cation component. 7. The method according to claim 1, wherein the alkaline earth metal element is Ca, Sr, B
7. One or more kinds of a, and the content thereof is 20 mol% or more and 45 mol% or less in terms of fluoride.
3. The ultraviolet-excited red phosphor described in 1. above. 8. The composition of the phosphor is αBaF ₂ .βGdF ₃
ΓB ₂ O ₃ : δEu (0.25 ≦ α ≦ 0.45, 0.15 ≦
β ≦ 0.6, 0.2 ≦ γ ≦ 0.4, 0.04 ≦ δ ≦ 0.1)
The ultraviolet-excited red phosphor according to any one of claims 1 to 6, which is represented by: