JP2851006B2 - Phosphor - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a novel phosphor, and more particularly, to a phosphor of a trivalent metal phosphate capable of obtaining high-luminance light of each color by using a specific activator. About the body.

[Prior Art] Conventionally, as a trivalent metal phosphate-based phosphor using a rare earth as an activator, (Ln _1-x Ln ′ _x ) PO ₄ (where Ln is yttrium,
Gadolinium or lanthanum, Ln 'is europium, terbium, samarium, dysprosium, praseodymium, neodymium, ytterbium, holmium and erbium) [RCRoop, J. Electrochem. Soc. 115, 8, 841 (19
68)], (Ln, Ce) PO ₄ (where Ln is yttrium, gadolinium or lanthanum) [RCRoop, J. Electrochem. Soc. 1
15,5,531 (1968)], (La, Ce, Tb) PO ₄ [JCBourcet e
t.al., Rare Eearth Reseach Conf. 441 (1971)], (La
_1-x Gd _x ) P ₃ O ₉ : Ce, Tb [HSKiliaan et.al., J. Solid Sta.
te Chem. 74, 1, 39 (1988)].

Among these known phosphors, the LnPO ₄ system is a rare earth orthophosphate and is a crystalline base having a monazite structure (Ln ′: for example, lanthanum, gadolinium) or a xenotime structure (Ln ′: for example, yttrium), and an Ln′P ₃ O ₉ system. Is a rare earth metaphosphate.

[Problems to be Solved by the Invention] Each of the above-mentioned known rare-earth activated phosphors includes ultraviolet rays, electron beams, X rays,
It is known that each activated rare earth emits light under various excitations such as radiation and vacuum ultraviolet rays, and some of them have already been put into practical use for specific applications. However, from the viewpoint of practicality, a phosphor having higher emission luminance than these phosphors is desired.

Accordingly, an object of the present invention is to provide a novel phosphate phosphor that emits light with higher luminance than the conventional rare earth phosphate-based phosphor.

Means for Solving the Problems In order to achieve the above object, the present inventors have searched for a rare earth phosphate-based host suitable for activating various rare earth elements. As a result, conventionally known LnPO ₄ (Ln: described above)
Rare earth orthophosphate or LnP ₃ O ₉ ((Ln: as described above) Ln ₃ PO ₇ different from the rare earth metaphosphate host
When an appropriate amount of rare earth is activated in this matrix, it emits light with high brightness under excitation of ultraviolet rays, electron beams, X-rays, vacuum ultraviolet rays, etc. The inventors have found that a phosphor that emits light according to the active rare earth can be obtained, and have completed the present invention.

That is, the present invention provides a composition formula (Ln _1-x Ln ′ _x ) ₃ PO ₇ (where Ln is at least one selected from yttrium, lanthanum and gadolinium, and Ln ′ is terbium, europium, praseodymium, samarium, dysprosium) And at least one activator selected from thulium, and x is a number satisfying 0.0001 ≦ x ≦ 0.5.) The phosphor of trivalent metal phosphate represented by the following formula:

It should be noted that it is difficult for the rare earth-activated orthophosphate phosphor and metaphosphate phosphor to exhibit efficient light emission under ultraviolet (eg, 254 nm) excitation when, for example, only terbium (Tb) is used as the activator. Was. Therefore, it was necessary to increase the efficiency by co-activating cerium (Ce). The phosphor of the present invention is a novel phosphor that emits light at least equal to or more than LnPO ₄ : Ce, Tb currently in practical use, for example, LaPO ₄ : Ce, Tb alone, and even Tb alone.

 Hereinafter, the present invention will be described in detail.

The phosphor of the present invention represented by the above composition formula is manufactured by the following manufacturing method.

First, as a phosphor material, (a-1) a first compound group consisting of yttrium oxide (Y ₂ O ₃ ), lanthanum oxide (La ₂ O ₃ ), and gadolinium oxide (Gd ₂ O ₃ ); At least one compound selected from a compound group consisting of a yttrium compound, a lanthanum compound, and a gadolinium compound, which can be converted to Y ₂ O ₃ , La ₂ O ₃ , and Gd ₂ O ₃ (a-2 ) Terbium oxide (Tb ₄ O ₇ ), europium oxide (Eu ₂ O ₃ ), praseodymium oxide (Pr ₆ O ₁₁ ), samarium oxide (Sm ₂ O ₃ ), dysprosium oxide (Dy ₂ O ₃ ), thulium oxide A first compound group consisting of (Tm ₂ O ₃ ), and Tb ₄ O ₇ , Eu ₂ O ₃ , Pr ₆ O ₁₁ , Sm ₂ O ₃ , Dy ₂ O ₃ ,
(B) at least one compound selected from the group consisting of a terbium compound, a europium compound, a praseodymium compound, a samarium compound, a dysprosium compound and a thulium compound, which can be converted to Tm ₂ O _3; A first group of compounds consisting of monoammonium phosphate ((NH ₄ ) H ₂ PO ₄ ) and diammonium phosphate ((NH ₄ ) ₂ HPO ₄ ), and a second group of compounds which can easily become a phosphate source at high temperatures. Or at least one compound selected from the compound group consisting of: or (a) at least one of yttrium, lanthanum, gadolinium and terbium, europium, praseodymium, samarium, dysprosium, thulium at least one and a coprecipitated oxide, (b) first ammonium phosphate _{((NH 4) H 2 PO} 4) Beauty second ammonium phosphate _{((NH 4) 2 HPO 4} ) first group of compounds consisting of, and at least one second compound group, compound a compound selected from the group consisting of obtaining easily be phosphate source at high temperatures And are used.

(C) When magnesium is added as required, for example, magnesium chloride (MgCl ₂ .6H ₂ O), magnesium hydroxide [Mg (OH) ₂ ], magnesium nitrate [Mg
(NO ₃ ) ₂ · 6H ₂ O] and at least one selected from the group consisting of magnesium carbonate (MgCO ₃ ) and a second compound group which can be easily converted to MgO at a high temperature. .

In addition, for the purpose of improving the brightness or life of the real sphere, the above-mentioned raw materials, and the resulting phosphors, include antimony, tin, lead and zinc; monovalent metals such as lithium, sodium and potassium; and calcium, barium and strontium. Valence metals: Bismuth, silicon, hafnium, zirconium, indium and the like may be contained in a trace amount of about 10 to 1000 ppm.

Each of the above phosphor materials is, for example, (Ln _1-x Ln ′ _x ) ₃ PO ₇ (where Ln and Ln ′ are the same as above, and x is the same as the above 0.00).
It is a number satisfying 01 ≦ x ≦ 0.5. When magnesium is contained, the composition formula is (Ln _1-x Ln ′ _x ) ₃ PO ₇ · aMg ₃ (PO ₄ ) ₂ (where Ln, Ln ′ and x are the same as above, and a is It is a number that satisfies 0 ≦ a ≦ 1.) The required amounts are weighed and mixed sufficiently so as to satisfy the mixed composition formula. Mixing may be performed dry using a ball mill, mixer mill, mortar, or the like, or may be performed wet using water or the like as a medium in a paste state.

Next, the phosphor material mixture is filled in a heat-resistant container such as an alumina crucible or a quartz crucible and fired. Calcination is performed at about 500 ° C in air, in a neutral atmosphere such as an argon gas atmosphere or a nitrogen gas atmosphere, or in a reducing atmosphere such as a nitrogen gas atmosphere or a carbon gas atmosphere containing a small amount of hydrogen gas.
Or once or twice at a temperature of 1700 ° C. When firing is performed twice, the phosphor mixture is returned to room temperature after the first firing, the mixture is loosened if necessary, and firing is performed again.

In firing, at least the final firing (first firing in the case of one firing) must be performed in a neutral atmosphere or in a reducing atmosphere in order to ensure that the valence of the rare earth activator such as terbium is trivalent. It is preferably performed in an atmosphere. The firing time varies depending on the weight of the phosphor raw material mixture filled in the heat-resistant container, but generally, 2 to 5 hours is appropriate in the above firing temperature range. When a compound of an alkali metal element, a boron compound, or the like is used as a flux for accelerating the reaction at the time of firing, firing at a lower temperature and in a shorter time can be performed, thereby improving the light emission characteristics.

After calcination, the phosphor of the present invention can be obtained by treating the resulting calcined product by various operations generally employed in phosphor production such as grinding, washing, drying and sieving.

Since the phosphor of the present invention emits high-intensity blue to red light under excitation of ultraviolet rays, electron beams, X-rays, vacuum ultraviolet rays, etc., it can be used in fluorescent lamps, cathode ray tubes, X-ray image converters, plasma display devices, Can be used. In particular, the phosphor of the present invention emits light with higher luminance under excitation of ultraviolet light and vacuum ultraviolet light than conventionally known cerium and terbium-activated LaPO ₄ -based phosphors. Therefore, for example, it is also useful as a green component of a three or four wavelength high color rendering lamp.

As shown in the examples, in the phosphor of the present invention, in terms of luminance, Ln is most preferably Y, followed by Gd and La. Therefore, it is recommended that the base of the phosphor of the present invention be composed of Y or Y as a main part, and the remainder composed of at least one solid solution of Gd and La. In such a case, the molar ratio of Y is preferably selected in the range of 0.7 to 1 mol, and the remaining
0.3 mol or less is preferably selected in the order of Gd and La.

When the phosphor of the present invention is used as various coloring phosphors used for a phosphor film of a high color rendering fluorescent lamp, the following properties are satisfied.

1) 400 to 460 nm, preferably around 450 nm for blue light emitting phosphors, and 510 to 560 nm for green light emitting phosphors
m preferably around 540 nm, 60 for red emitting phosphors
Main emission wavelengths in the range of 0 to 640 nm, preferably in the vicinity of 610 nm. Further, the blue-green light emitting phosphor should have a main emission wavelength in the range of 460 to 490 nm, preferably in the vicinity of 480 nm.

2) High emission luminance.

3) The emission luminance decreases with time, that is, the deterioration is small.

In addition, the phosphor of the present invention can be used for a phosphor film of a high color rendering lamp by applying the phosphor to specific several colors and using the phosphor in combination with the following conventional phosphors. As the conventional blue-colored phosphor, a barium / magnesium aluminate phosphor activated with divalent europium (hereinafter abbreviated as BAM: Eu ²⁺ phosphor) and an alkaline earth halophosphate phosphor are used. ing. As the green light emitting phosphor, a lanthanum phosphate phosphor and a magnesium aluminate phosphor activated with cerium / terbium are used. A yttrium oxide phosphor activated with trivalent europium is used as a red-coloring phosphor. As the blue-green light-emitting phosphor, an alkaline earth aluminate phosphor, an alkaline earth halophosphate phosphor, and an alkaline earth haloborophosphate phosphor activated by divalent europium are used. .

[Examples] Hereinafter, the present invention will be described with reference to examples.

In the examples, the relative luminance was measured by measuring the powder luminance of the obtained phosphor under ultraviolet light having a wavelength of 253.7 nm.

Examples 1-3 Co-precipitated oxide of Y or Gd, Tb as Y or Gd source and Tb source,
(NH ₄ ) ₂ HPO ₄ was weighed stoichiometrically as a phosphoric acid source so as to have a predetermined composition formula, and 10 wt% of ammonium chloride was added as a flux. The mixed powder was placed in an alumina crucible and calcined in air at 500 ° C. for 2 hours. After cooling to room temperature, the fired product was pulverized, put again in an alumina crucible, fired at 1400 ° C. for 2 hours in a reducing atmosphere, and subjected to a predetermined treatment, whereby Examples 1 to 3 in Table 1 were added.
The following phosphor was produced. LaPO for comparison at the same time
₄ : Ce, Tb phosphors were produced in the same manner (Comparative Example).

The relative luminance of the obtained phosphor was measured. Table 1 shows the results.

As shown in Table 1, the overall characteristics are improved as compared with the LaPO ₄ : Ce, Tb phosphor. Fig. 1 shows (Y _0.9 T
showing an emission spectrum of b _{0.1) 3} PO _7.

Examples 4 to 8 Y source and Eu, Sm, Tm, Dy or Pr source as Y and Eu, Sm, Tm,
(NH ₄ ) ₂ HPO ₄ was weighed stoichiometrically to obtain a predetermined mixed composition formula as a coprecipitated oxide of Dy and Pr, and a phosphoric acid source. Phosphors such as those shown in Examples 4 to 8 in Table 1 were produced, and their characteristics were measured.

As shown in FIGS. 2 to 5, good bright light emission peculiar to each rare earth is obtained.

Examples 9 to 11 Except that MgCl ₂ .6H ₂ O was stoichiometrically weighed as a Mg source so as to have a predetermined mixed composition formula, and this was added.
In the same manner as in Example 3, the phosphors shown in Examples 9 to 11 in Table 1 were produced, and their characteristics were measured. As a result, the same good emission spectrum as that shown in FIG. 1 was obtained.

[Effects of the Invention] The phosphor of the trivalent metal phosphate of the present invention is a novel Ln ₃ PO ₇ type phosphor, and can obtain remarkably high luminance as compared with conventional phosphors.

[Brief description of the drawings]

Figure 1 is the present invention (Y _0.9 Tb _0.1) an emission spectrum of ₃ PO ₇ phosphor (Example 1), the phosphor matrix and Y ₃ PO ₇ in FIG. 2-FIG. 5 are each present invention FIG. 7 is an emission spectrum diagram of a phosphor (Examples 4, 5, 6, and 7 respectively) using europium, samarium, thulium, or dysprosium as an activator.

Claims (4)

(57) [Claims] 1. Composition formula (Ln _1-x Ln ′ _x ) ₃ PO ₇ (where Ln is at least one selected from yttrium, lanthanum and gadolinium, Ln ′ is terbium, europium, praseodymium, samarium, dysprosium and At least one activator selected from thulium, and x is a number satisfying 0.0001 ≦ x ≦ 0.5.) A phosphor of a trivalent metal phosphate represented by the following formula: 2. The phosphor according to claim 1, wherein x is a number satisfying 0.005 ≦ x ≦ 0.3. 3. The phosphor according to claim 1, wherein the content of yttrium is 0.7 to 1.0 mol in a molar ratio with respect to all Ln, and Ln ′ is terbium. 4. The phosphor according to claim 1, wherein said composition further contains magnesium.