JPH0790266A - Infrared fluorescent emitter - Google Patents

Abstract

(57) [Summary] [Purpose] To provide an infrared-emitting phosphor in the form of ultrafine particles with high emission intensity. [Configuration] formula, in _{M 1-xy Nd x Yb y} PO 4 ( wherein, M is Al, Bi, B, In, Ga, Sc, be one kind of element selected from the group consisting of Gd and Ce ;
0 ≦ x ≦ 0.5; 0 ≦ y ≦ 0.5 and 0 <x + y <1
Is. _{); D 1-xy Nd x} Yb y PO 4 ( wherein, D is Al, Bi, B, In, Ga, Y, Lu, Sc, Gd,
At least 2 selected from the group consisting of La and Ce
More than one element, provided that Y-Lu, Y-La, La-
Excluding the combination of elements Lu and Y-La-Lu; 0
≦ x ≦ 0.5; 0 ≦ y ≦ 0.5 and 0 <x + y <1. ); Or, in _{AB 1-xy Nd x Yb y} PO 4 ( wherein, A is at least one element selected from the group consisting of alkali metals and alkaline earth metals; B
Is Al, Bi, B, In, Ga, Y, Lu, Sc, G
at least one element selected from the group consisting of d, La and Ce; 0 ≦ x ≦ 0.5; 0 ≦ y ≦
0.5; and 0 <x + y <1. ) Infrared emitting phosphor represented by.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an infrared emitting phosphor. More specifically, the present invention relates to microparticulation of an infrared-emitting phosphor having an emission spectrum in the infrared wavelength region, which is excited by infrared rays, and modification of its structure and composition.

[0002]

2. Description of the Related Art In recent years, mainly in the distribution industry, product management by bar codes has been actively performed in each industry.
Bar codes are also printed on various prebate cards or pass cards, and the bar codes are read using an optical reading device such as a scanner. In addition to these cards, for credit cards and the like, various methods have been proposed in which these cards are provided with anti-counterfeiting means, or whether or not the cards are forged. As one of them,
Marks such as barcodes are printed with phosphor-containing ink to form latent image marks, and the latent image marks are irradiated with a semiconductor laser to excite the phosphors, and the light emitted from the phosphors is received to provide barcode information. An optical reader for reading is proposed.

According to this method, since the fluorescence signal is detected only when there is a recorded mark, a forged or altered card can be surely found. Also, since the content of the latent image mark is only known to the authentic card manufacturer, it is possible to falsify or alter the card itself.
It's extremely difficult.

As such a phosphor, for example, the general formula, in _{QD 1-xy Nd x Yb y} P 4 O 12 ( wherein, Q is selected from the group consisting of Li, Na, K, Rb and Cs At least one element, and D is S
at least one element selected from the group consisting of c, Y, La, Ce, Gd, Lu, Ga and In,
0.05 ≦ x ≦ 0.999, 0.001 ≦ x ≦ 0.95
0, x + y ≦ 1.0. ) Is used as the phosphoric acid-based phosphor (see, for example, JP-B-53-40594).
(See Japanese Patent Publication).

[0005]

However, this type of phosphor has a large particle size of 7 μm or more, and it is necessary to pulverize it when it is used for offset printing or an ink ribbon. This crushing causes a problem that the crystallinity and composition of the phosphor are impaired and the emission intensity is significantly reduced.

Therefore, an object of the present invention is to solve the problem of particle size, which the above-mentioned conventional products have, and to provide an ultrafine particle-shaped infrared-emitting phosphor having a high emission intensity.

[0007]

To SUMMARY OF THE INVENTION To achieve the above object, the present invention, (1) the general formula, in _{M 1-xy Nd x Yb y} PO 4 ( wherein, M is Al, Bi, B , In, Ga, Sc, Gd
1 element selected from the group consisting of and Ce; 0 ≦ x ≦ 0.5; 0 ≦ y ≦ 0.5 and 0 <x + y
<1. ); (2) the general formula, D in _{1-xy Nd x Yb y PO} 4 ( wherein, D is Al, Bi, B, In, Ga, Y, Lu,
It is at least two elements selected from the group consisting of Sc, Gd, La and Ce, provided that Y-Lu and Y-
The combination of elements of La, La-Lu and Y-La-Lu is excluded; 0 ≦ x ≦ 0.5; 0 ≦ y ≦ 0.5 and 0 <
x + y <1. ); Or, (3) the general _{formula, AB 1-xy Nd x Yb} y PO 4 ( in the formula, A is at least one element selected from the group consisting of alkali metals and alkaline earth metals B is Al, Bi, B, In, Ga, Y, Lu, S
at least one element selected from the group consisting of c, Gd, La and Ce; 0 ≦ x ≦ 0.5; 0 ≦
y ≦ 0.5; and 0 <x + y <1. ); The infrared-emitting phosphor represented by These phosphors are
At least one element selected from the group consisting of r and Tb can be further contained as a luminescence sensitizer. The particle size of these phosphors is in the range of 0.1 μm to 3 μm.

[0008]

It has been found that the novel infrared-emitting phosphor of the present invention exhibits high emission intensity with respect to infrared excitation light even though it is ultrafine particles.

When the infrared-emitting phosphor of the present invention is manufactured,
As raw materials, ammonium phosphate have been used in general conventionally _{[(NH 4) a H b} PO 4, where a + b = 3]
In place of orthophosphoric acid (H ₃ P0 ₄ ) or phosphate (A _3-x H _x PO ₄ , where A is at least one element of an alkali metal or alkaline earth metal) By using it, it is possible to prevent the generation of ammonia gas during firing, simplify the entire manufacturing process by eliminating the need for the detoxification process of this gas, and improve the productivity as well as the particles of the resulting phosphor. The diameter can be further reduced.

Conventional ammonium phosphate [(NH ₄ ) _a
The particle size of the phosphor obtained by the method using H _b PO ₄ , but a + b = 3] can be reduced to about 7 μm at most, but according to the method of the present invention, ammonium phosphate [ (NH ₄ ) _a H _b PO ₄ , where a + b
= 3], the particle diameter can be reduced to 1/10 or less of the particle diameter of the phosphor using. Particularly, according to the method using the above phosphate, the particle size of the phosphor is 3 μm or less, for example,
The average particle size can be reduced to 0.8 μm or less. Further, according to this method, it is possible to obtain a phosphor having a particle size of 0.1 μm.

Therefore, the phosphor obtained by the method of the present invention can be directly used in use without secondary processing such as pulverization. When the phosphor obtained by the conventional method using ammonium phosphate is finely pulverized, the emission intensity is lowered, but the infrared emission phosphor of the present invention has a very high emission intensity in the state of ultrafine particles. Since the infrared-emitting phosphor of the present invention is ultrafine particles, when it is used for offset printing or an ink ribbon, not only the coating preparation becomes very easy but also microencapsulation becomes possible.

According to the method of the present invention, orthophosphoric acid or phosphate can be used alone or in combination. In order to obtain high emission intensity, among phosphates (A _3-x H _x PO ₄ , where A is at least one element selected from alkali metals and alkaline earth metals), , X are preferably large.

The infrared-emitting phosphor of the present invention emits light due to the forbidden transition of 4f electrons of Nd and Yb. The reason why the emission intensity is high in spite of the ultrafine particles is that the crystallinity of the orthophosphate as a base material is high. Is good, and a lot of Nd and Yb
It is thought that this is due to the fact that Further, it is considered that the crystallinity is further improved and the emission intensity is improved by adding a small amount of alkali metal or alkaline earth metal.

[0014] (i) general _{formula, M 1-xy Nd x Yb} y PO 4
(In the formula, M is Al, Bi, B, In, Ga, Sc, Gd.
1 element selected from the group consisting of and Ce; 0 ≦ x ≦ 0.5; 0 ≦ y ≦ 0.5 and 0 <x + y
When producing an infrared-emitting phosphor represented by <1),
At least one of neodymium and ytterbium
Seed compound and Al, Bi, B, In, Ga, Sc, G
Compound of one element selected from the group consisting of d and Ce and; (ii) general formula, D in _{1-xy Nd x Yb y PO} 4 ( wherein, D is Al, Bi, B, In, Ga, Y, Lu, Sc, Gd,
At least 2 selected from the group consisting of La and Ce
More than one element, provided that Y-Lu, Y-La, La-
Excluding the combination of elements Lu and Y-La-Lu; 0
≦ x ≦ 0.5; 0 ≦ y ≦ 0.5 and 0 <x + y <1), and at least one compound of neodymium and ytterbium; Al, Bi, B, In, Ga, Y, Lu, S
at least two elements selected from the group consisting of c, Gd, La and Ce (provided that Y-Lu, Y-La,
The combination of elements La-Lu and Y-La-Lu with a compound of excluded); or, (iii) in the general _{formula, AB 1-xy Nd x Yb} y PO 4 ( wherein,
A is at least one element selected from the group consisting of alkali metals and alkaline earth metals; B is A
l, Bi, B, In, Ga, Y, Lu, Sc, Gd, L
at least one element selected from the group consisting of a and Ce; 0 ≦ x ≦ 0.5; 0 ≦ y ≦ 0.5;
And 0 <x + y <1), at least one compound selected from neodymium and ytterbium and Al, Bi, B, I
n, Ga, Y, Lu, Sc, Gd, La and a compound of at least one element selected from the group consisting of Ce; and a raw material powder consisting of orthophosphoric acid (H ₃ PO
₄ ) or A _3-x H _x PO ₄ (wherein A is at least one element of an alkali metal or an alkaline earth metal), and 400 to 15 is added.
The excess phosphate and other impurities are removed by baking at a temperature within the range of 00 ° C., followed by air cooling, and subsequent hydrothermal treatment at 50 ° C. or higher.

In the infrared emitting phosphor of the present invention, as the compounds of neodymium and ytterbium, for example, oxides, chlorides, carbonates, nitrates, acetates and the like of these can be preferably used. Similarly, Al, Bi,
B, In, Ga, Y, Lu, Sc, Gd, La and C
As the compound of the element e, for example, these oxides, chlorides, carbonates, nitrates, acetates and the like can be preferably used. These compounds can also be used by dissolving them in a dilute mineral acid (eg dilute sulfuric acid, dilute hydrochloric acid, dilute nitric acid, etc.) before firing.

For firing, the raw materials are put in a crucible, and in the air,
400-1500 ° C, preferably 650 ° C-1000
It is carried out by heating at a temperature of about 2 hours to 24 hours.

Hereinafter, the production of the infrared-emitting phosphor of the present invention will be specifically illustrated with reference to examples.

Example 1 Nd ₂ O ₃ : 3.5 g, Yb ₂ O ₃ : 4.0 g, Gd ₂
O _3: 29.0 g and H ₃ PO _4: raw material were mixed thoroughly made of 60.0 g, was filled in a covered crucible made of alumina, placed in an electric furnace, to 700 ° C. position from room constant Atsushi Nobori The temperature was increased at a speed of 2 hours, and then, firing was performed at 700 ° C. for 6 hours. Immediately after the firing was completed, it was taken out of the electric furnace and allowed to cool in air. Next, boiling water of 100 ° C. was put into the crucible, boiled, the phosphor was taken out from the crucible, washed with 1N nitric acid, washed with water, and dried to obtain a desired phosphor. The composition of the obtained phosphor is Nd _0.1 Yb
_{It was 0.1} Gd _0.8 PO ₄ .

Example 2 The raw material composition of Example 1 was changed to Nd ₂ O ₃ : 3.5 g,
Yb ₂ O ₃ : 4.0 g, Gd ₂ O ₃ : 10.9 g, Y ₂
A phosphor was obtained by the same method as that described in Example 1 except that O ₃ : 11.3 g and H ₃ PO ₄ : 60.0 g were used. The composition of the obtained phosphor is Nd _0.1 Y
b was _0.1 Gd _0.3 Y _0.5 PO _4.

Example 3 The raw material composition in Example 1 was changed to Nd ₂ O ₃ : 3.5 g,
Yb ₂ O ₃ : 4.0 g, Gd ₂ O ₃ : 3.6 g, Y ₂ O
_A phosphor was obtained by the same method as described in Example 1 except that the amounts were changed to ₃ : 15.3 g and LiH ₂ PO ₄ : 65.0 g. The composition of the obtained phosphor is Nd _0.1.
It was _{Yb 0.1 Gd 0.1 Y 0.7 PO 4} .

Example 4 A phosphor was obtained in the same manner as in Example 3, except that the firing temperature was changed to 900 ° C. The composition of the obtained phosphor is Nd _0.1 Yb _0.1 G
It was d _0.1 Y _0.7 PO ₄ .

[0022] The raw material composition in Example 5 Example _{1, Nd 2 (CO 3)} 3 · 8
H ₂ O: 6.1 g, Yb ₂ (CO ₃ ) ₃ : 5.2 g, G
_{d 2 (CO 3) 3 ·} 2H 2 O: 5.3g, Y 2 (CO
_{3) 3 · 2H 2 O:} 27.6g and LiH ₂ PO _4:
A phosphor was obtained by the same method as that described in Example 1 except that the amount was changed to 65.0 g. The composition of the obtained phosphor was Nd _0.1 Yb _0.1 Gd _0.1 Y _0.7 PO ₄ .

Example 6 The raw material composition of Example 1 was changed to Nd ₂ O ₃ : 3.5 g,
Yb ₂ O ₃ : 4.0 g, In ₂ O ₃ : 2.8 g, Lu ₂
A phosphor was obtained by the same method as that described in Example 1 except that O ₃ : 27.9 g and LiH ₂ PO ₄ : 65.0 g were changed. The composition of the obtained phosphor is Nd.
_{It was 0.1} Yb _0.1 In _0.1 Lu _0.7 PO ₄ .

Example 7 The raw material composition in Example 1 was changed to Nd ₂ O ₃ : 3.5 g,
Gd ₂ O ₃ : 3.6 g, Y ₂ O ₃ : 18.0 g and L
A phosphor was obtained by the same method as that described in Example 1, except that iH ₂ PO ₄ was changed to 65.0 g. The composition of the obtained phosphor was Nd _0.1 Gd _0.1 Y _0.8 PO ₄ .

Example 8 The raw material composition in Example 1 was changed to Nd ₂ O ₃ : 3.5 g,
A phosphor was obtained by the same method as described in Example 1 except that In ₂ O _{3 was} 2.8 g, Lu ₂ O _{3 was} 31.8 g, and LiH ₂ PO _{4 was} 65.0 g. The composition of the obtained phosphor is Nd _0.1 In _0.1 Lu _0.8 PO
_{Was 4} .

Example 9 The raw material composition in Example 1 was changed to Yb ₂ O ₃ : 4.0 g,
Gd ₂ O ₃ : 3.6 g, Y ₂ O ₃ : 18.0 g and L
A phosphor was obtained by the same method as that described in Example 1, except that iH ₂ PO ₄ was changed to 65.0 g. The composition of the obtained phosphor was Yb _0.1 Gd _0.1 Y _0.8 PO ₄ .

Example 10 The raw material composition in Example 1 was changed to Yb ₂ O ₃ : 4.0 g,
A phosphor was obtained by the same method as described in Example 1 except that In ₂ O _{3 was} 2.8 g, Lu ₂ O _{3 was} 31.8 g, and LiH ₂ PO _{4 was} 65.0 g. The composition of the obtained phosphor is Yb _0.1 In _0.1 Lu _0.8 PO
_{Was 4} .

Comparative Example 1 The raw material composition in Example 1 was changed to Nd ₂ O ₃ : 30 g, Y
b ₂ O ₃ : 4.0 g, Li ₂ CO ₃ : 11.0 g and (NH ₄ ) H ₂ PO ₄ : 140 g were changed to obtain a phosphor by the same method as described in Example 1. It was The composition of the obtained phosphor is LiNd _0.9 Yb _0.1 P
It was ₄ O ₁₂ .

Comparative Example 2 The phosphor obtained in Comparative Example 1 was placed in a zirconia ball mill and wet-ground using water as a medium. The composition of the obtained phosphor remained as in Comparative Example 1.

Comparative Example 3 The raw material composition of Example 1 was changed to Yb ₂ O ₃ : 4.0 g,
A phosphor was obtained by the same method as described in Example 1 except that Y ₂ O ₃ : 20.0 g, Li ₂ CO ₃ : 11.0 g and (NH ₄ ) H ₂ PO ₄ : 140 g were used. It was The composition of the obtained phosphor is LiY _0.9 Yb _0.1 P ₄
It was O ₁₂ .

Comparative Example 4 The phosphor obtained in Comparative Example 3 was placed in a ball mill made of zirconia and wet-milled with water as a medium. The composition of the obtained phosphor remained as in Comparative Example 3.

The above Examples 1 to 10 and Comparative Examples 1 to 4
The average particle size and emission characteristics of each phosphor obtained in step 1 are shown in Table 1 below.
Shown in. The average particle size of the phosphor was measured using a centrifugal sedimentation particle size distribution meter. The emission characteristics were measured by exciting with a light source having a wavelength of 810 nm and receiving the emitted light at 980 nm with a silicon photodetector to measure the emission intensity (measurement A). Also, Yb
A single phosphor is excited by a light source with a wavelength of 950 nm and then turned off.
After 00 μs, the emission intensity was measured by receiving afterglow with a silicon photodetector having a peak sensitivity of 980 nm (measurement B). The luminescence intensity was displayed with the value of the sample of Comparative Example 1 being 100.

[0033]

[Table 1] Table 1 Average particle size Emission characteristic Sample (μm) Measurement A Measurement B Example 1 0.6 90 90 2 0.8 88 3 0.6 95 95 4 2.9 123 5 0.9 100 6 0.8 92 7 0.6 0.6 67 8 0.7 70 9 0.7 0.7 115 10 0.5 106 Comparative Example 1 7.5 100 2 0.6 20 3 8.0 8.0 100 4 0.6 10

As is clear from the results shown in Table 1 above, according to the present invention, an infrared-emitting phosphor having an average particle size of 3 μm or less and a high emission intensity can be obtained.

The emission spectra of the phosphor obtained in Example 3 and the phosphor obtained in Comparative Example 1 are shown in FIG. Figure 1
1A is an emission spectrum of the phosphor obtained in Example 3, and FIG. 1B is an emission spectrum of the phosphor obtained in Comparative Example 1. As is clear from a comparison of the emission spectra shown in FIGS. 1 (a) and 1 (b), the infrared light emitting phosphor of the present invention has characteristics which are completely different from those of the infrared light emitting phosphor of Comparative Example 1. It can be understood that it is an infrared-emitting phosphor having the same.

A scanning electron micrograph showing the particle structures of the phosphor obtained in Example 3 and the phosphor obtained in Comparative Example 1 is shown in FIG. FIG. 2A is a scanning electron micrograph showing the particle structure of the phosphor obtained in Example 3, and FIG.
(B) is a scanning electron micrograph showing the particle structure of the phosphor obtained in Comparative Example 1. 2 (a) and 2
As is clear from comparison of the photographs of (b), it can be understood that the phosphor of the present invention is ultrafine particles having a completely different particle shape and a significantly smaller particle size than the phosphor of Comparative Example 1.

[0037]

As described above, according to the present invention, it is possible to obtain a novel infrared-emitting phosphor having ultrafine particles and high emission intensity.

[Brief description of drawings]

1A is a waveform diagram showing an emission spectrum of a phosphor obtained in Example 3, and FIG. 1B is a waveform diagram showing an emission spectrum of a phosphor obtained in Comparative Example 1.

2 (a) is a scanning electron microscope photograph showing the particle structure of the phosphor obtained in Example 3, and FIG. 2 (b) shows the particle structure of the phosphor obtained in Comparative Example 1. FIG. It is a photograph figure by a scanning electron microscope.

Claims (9)

[Claims] 1. A general _{formula, M 1-xy Nd x Yb} y PO 4 ( wherein, M is Al, Bi, B, In, Ga, Sc, Gd
1 element selected from the group consisting of and Ce; 0 ≦ x ≦ 0.5; 0 ≦ y ≦ 0.5 and 0 <x + y
<1. ) Infrared emitting phosphor represented by. 2. The infrared-emitting phosphor according to claim 1, further containing at least one element selected from the group consisting of Pr and Tb as a luminescence sensitizer. 3. The infrared-emitting phosphor according to claim 1, having a particle size in the range of 0.1 μm to 3 μm. Wherein the general formula, in _{D 1-xy Nd x Yb y} PO 4 ( wherein, D is Al, Bi, B, In, Ga, Y, Lu,
It is at least two elements selected from the group consisting of Sc, Gd, La and Ce, provided that Y-Lu and Y-
The combination of elements of La, La-Lu and Y-La-Lu is excluded; 0 ≦ x ≦ 0.5; 0 ≦ y ≦ 0.5 and 0 <
x + y <1. ) Infrared emitting phosphor represented by. 5. The infrared-emitting phosphor according to claim 4, which further contains at least one element selected from the group consisting of Pr and Tb as a luminescence sensitizer. 6. The infrared-emitting phosphor according to claim 4, which has a particle size in the range of 0.1 μm to 3 μm. 7. A general _{formula, AB 1-xy Nd x Yb} y PO 4 ( in the formula, A is at least one element selected from the group consisting of alkali metals and alkaline earth metals; B Is Al, Bi, B, In, Ga, Y, Lu, S
at least one element selected from the group consisting of c, Gd, La and Ce; 0 ≦ x ≦ 0.5; 0 ≦
y ≦ 0.5; and 0 <x + y <1. ) Infrared emitting phosphor represented by. 8. The infrared-emitting phosphor according to claim 7, further containing at least one element selected from the group consisting of Pr and Tb as a luminescence sensitizer. 9. The infrared-emitting phosphor according to claim 7, which has a particle size in the range of 0.1 μm to 3 μm.