JPH07110946B2 - Phosphor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a phosphor, and more particularly to a rare earth phosphate phosphor containing terbium as an activator.

[Prior Art] Conventionally, as a green light emitting phosphor using a rare earth element as an activator, a terbium activated yttrium silicate phosphor (Y ₂ Si
O ₅ : Tb) and terbium-activated lanthanum phosphate phosphor (LaP
O ₄ : Tb) or the like using terbium as an activator, or cerium and terbium activated yttrium silicate phosphor (Y ₂ Si
O ₅ : Ce, Tb), cerium and terbium activated lanthanum phosphate phosphors (LaPO ₄ : Ce, Tb) and the like having cerium and terbium as activators are known. Since these phosphors have a very narrow half-width of emission spectrum, they have a special product suitable for a three-wavelength lamp having a high color rendering property. In particular, cerium- and terbium-activated lanthanum phosphate phosphors are widely used as green light-emitting phosphors for three-wavelength lamps because of their high efficiency and low manufacturing cost.

Further, in order to improve the characteristics of the rare earth phosphate phosphor using cerium and terbium as an activator, it has been proposed to add various components. For example, JP-A-57-
In 133182 publication, adding an alkali metal element,
Addition of hafnium and / or zirconium to JP-A-57-187383, addition of magnesium to JP-A-59-129287, and JP-A-62-89.
Japanese Patent No. 790 describes that antimony is added.

An object of the present invention is to improve the characteristics of a rare earth phosphate phosphor having terbium as an activator, and particularly by using a novel additive, the brightness is improved and a fluorescent lamp using the phosphor is used. Is to improve the luminous flux of the lamp and the luminous flux maintenance factor.

[Summary of the Invention] According to the present invention, in order to achieve the above object, a rare earth phosphate phosphor containing terbium as an activator (here, the rare earth includes cerium, yttrium, lanthanum, gadolinium and lutetium). A phosphor, which is at least one element selected from the group, cerium is essential, and the same shall apply hereinafter), and contains at least one element of lead and soot, Provided.

The phosphor according to the present invention, for example, can be represented by the following composition _{formula, Ln 1-xy Ce x Tb} y PO 4: aPb, bSn ( wherein, Ln is yttrium, lanthanum, gadolinium,
And at least one rare earth element selected from the group consisting of lutetium, and a, b, x and y are numbers satisfying the relations of 0 <a + b ≦ 0.1 and 0 <x + y ≦ 1), that is, Ln _1-xy the ce _x Tb _y PO ₄ as the base, it is this as an essential condition that the addition of Pb and / or Sn.

INDUSTRIAL APPLICABILITY The phosphor of the present invention emits green light with high brightness under the excitation of ultraviolet rays having a wavelength of 253.7 nm, has a high initial brightness, and can supply a fluorescent lamp having a good luminous flux and luminous flux maintenance rate.

From the viewpoint of such effects, in the phosphor according to the present invention, the total of Pb content and Sn content per mol of the phosphor base is 10 or less.
^-6 to 10 ^-1 gram atom is preferred, 10 ^-5 to 10 ^-2
More preferably, it is a gram atom.

The phosphor according to the present invention may further contain a trace amount of other components, which are optionally or inevitably mixed. For example, the phosphor of the present invention may contain antimony (Sb), which can further improve the luminance and the luminous flux maintenance factor. The Sb content is 10 per mol of the phosphor matrix.
^-6 to 10 ^-3 gram atom is recommended.

Hereinafter, the present invention will be described in more detail.

The phosphor of the present invention is manufactured, for example, by the following manufacturing method.

First, as the phosphor material, (a) yttrium oxide (Y ₂ O ₃ ), lanthanum oxide (La ₂ O 3
₃ ), gadolinium oxide (Gd ₂ O ₃ ), and lutetium oxide (Lu ₂ O ₃ ), as well as Y ₂ O ₃ , La ₂ O ₃ , Gd ₂ O ₃ , and Lu easily at high temperature. _At least one compound selected from the group consisting of yttrium compounds, lanthanum compounds, gadolinium compounds, and lutetium compounds that can be converted to ₂ O ₃ , (b) cerium oxide (CeO ₂ ) and high temperature At least one compound selected from the group consisting of cerium compounds that can be easily converted to CeO ₂ , (c) terbium oxide (Tb ₄ O ₇ ) and Tb ₄ O ₇ easily at high temperature.
At least one compound selected from the group of compounds consisting of terbium compounds that can be changed to (d) ammonium dihydrogen phosphate ((NH ₄ ) H ₂ PO ₄ ) and ammonium dihydrogen phosphate ((NH ₄ ) ₂ HPO ₄ ) At least one compound selected from the group consisting of a first compound group consisting of), and a second compound group consisting of a second compound group that can easily become a phosphoric acid source at high temperature, (e) lead oxide (PbO), and easy at high temperature. At least one compound selected from the group consisting of lead compounds that can be converted to PbO, and (f) a compound selected from the group consisting of tin oxide (SnO ₂ ) and a tin compound that can be easily converted to SnO ₂ at high temperature Or (b) at least one of yttrium, lanthanum, gadolinium, and lutetium and a coprecipitated oxide of terbium and cerium, (b) Ammonium phosphate _{((NH 4) H 2 PO} 4) and a second ammonium phosphate _{((NH 4) 2 HPO 4} ) first group of compounds consisting of, and a second compound which can easily be phosphate source at high temperatures At least one compound selected from the group consisting of: (3) lead oxide (PbO), and at least one compound selected from the group consisting of lead compounds that can be easily converted to PbO at high temperature; ) At least one compound selected from the group consisting of tin oxide (SnO ₂ ) and a tin compound that can be easily converted to SnO ₂ at high temperature can be used.

Above, each phosphor material, for example, _{Ln 1-xy Ce x Tb y} PO 4: aPb, bSn ( wherein, Ln is yttrium, lanthanum, gadolinium,
And at least one kind of rare earth element selected from the group consisting of lutetium, and a, b, x and y are numbers satisfying the relations of 0 <a + b ≦ 0.1 and 0 <x + y ≦ 1) Similarly, weigh the required amount and mix well. The mixing may be performed by a dry method using a ball mill, a mixer mill, a mortar or the like, or may be performed by a wet method in a paste state using water as a medium.

Next, the phosphor raw material mixture is filled in a heat-resistant container such as an alumina crucible or a quartz crucible, and baked. Firing is performed at about 700 ° 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 containing a small amount of hydrogen gas or a carbon gas atmosphere.
Repeat once or twice at a temperature of 1300 ℃ to 1300 ℃. In the case of performing firing twice, after returning the phosphor mixture to room temperature after the first firing, the mixture is loosened if necessary, and then firing is performed again.

In calcination, in order to ensure that the valences of terbium and cerium are trivalent, at least the final calcination (when the calcination is once, the first calcination) is performed in a neutral atmosphere or a reducing atmosphere. Is preferable. Although the firing time varies depending on the weight of the phosphor raw material mixture filled in the heat resistant container and the like, it is generally 2 in the above firing temperature range.
~ 5 hours is appropriate. If a compound of an alkali metal element, a boron compound, or the like is used as a flux that promotes a reaction during firing, it becomes possible to perform firing at a lower temperature and a shorter time.

After firing, the obtained fired product is treated by pulverization, washing, drying, sieving, and other operations generally employed in phosphor production to obtain the phosphor of the present invention.

Since the phosphor of the present invention emits green light with high brightness under the excitation of ultraviolet rays as described above, it is versatile for various lamps mainly having a green light emitting component.

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

Incidentally, in the examples, the relative brightness is measured by measuring the powder brightness of the obtained phosphor under UV light having a wavelength of 253.7 nm, and the measurement of the lamp luminous flux and the luminous flux maintenance factor is the obtained fluorescence. A 40 W fluorescent lamp was manufactured using the body, and the luminous flux 100 hours after the lamp was turned on was defined as the initial luminous flux, and the ratio of the luminous flux 1000 hours after the initial luminous flux was measured as the luminous flux maintenance factor.

Examples 1 to 4: La source, Ce source, coprecipitated oxide of La, Ce, Tb as Tb source, (NH ₄ ) ₂ HPO ₄ as phosphoric acid source, and PbO as Pb source were stoichiometrically determined. Weigh it out so that it has a mixed composition formula, and after mixing it well, put the mixed powder in an alumina crucible and add 70
It was calcined at 0 ° C. for 2 hours. After cooling to room temperature, the calcined product was crushed, put again in a quartz crucible, calcined at 1200 ° C. for 2 hours in a reducing atmosphere, and subjected to a predetermined treatment to give a product as shown in Examples 1 to 4 in Table 1. A phosphor was produced. At the same time, for comparison, phosphors different only in not containing Pb were manufactured by the same method (Comparative Example).

The relative brightness, the luminous flux of the lamp, and the luminous flux maintenance factor of the obtained phosphor were measured. The results are shown in Table 1.

As shown in Table 1, the characteristics of the Pb-containing phosphor are totally improved as compared with the comparative example.

Examples 5 to 8: La source, Ce source, coprecipitated oxide of La, Ce, Tb as Tb source, (NH ₄ ) ₂ HPO ₄ as phosphoric acid source, SnO ₂ as Sn source were stoichiometrically determined. Were weighed so as to obtain the mixed compositional formula, and the phosphors as shown in Examples 5 to 8 in Table 1 were manufactured in the same manner as in Examples 1 to 4 above, and the characteristics were measured.

As shown in Table 1, the characteristics of the Sn-containing phosphor are totally improved as compared with the comparative example.

Examples 9 to 11: La source, Ce source, Coprecipitated oxide of La, Ce, Tb as Tb source, (NH ₄ ) ₂ HPO ₄ as phosphoric acid source, Y ₂ O ₃ as Y source, and Gd source
_{Gd 2 O 3, Lu 2 O} 3, and PbO were weighed out so as a stoichiometrically predetermined mixing composition formula as Pb source as Lu source, Table 1 in the same manner as in Example 1-4 below Phosphors as shown in Examples 9 to 11 were manufactured and their characteristics were measured.

As shown in Table 1, the characteristics of the phosphor obtained by substituting a part of La with Y, Gd or Lu are also improved as compared with the comparative example.

Examples 12, 13: La source, Ce source, coprecipitated oxide of La, Ce, Tb as Tb source, (NH ₄ ) ₂ HPO ₄ as phosphoric acid source, PbO as Pb source, S as Sn source
nO ₂ was stoichiometrically weighed so as to give a predetermined mixed composition formula, and the same procedure as in Examples 1 to 4 below was carried out.
Phosphors as shown in 12, 13 were manufactured and their characteristics were measured.

As shown in Table 1, the characteristics of the phosphor containing Pb and Sn are totally improved as compared with the comparative example.

[Effects of the Invention] As described above, the phosphor of the present invention contains at least one of lead and tin in the green light emitting rare earth phosphate phosphor having terbium as an activator. The overall light emitting characteristics including the brightness, the luminous flux of the lamp and the luminous flux maintenance factor are remarkably improved.

Claims (2)

[Claims] 1. A rare earth phosphate phosphor containing terbium as an activator (wherein rare earth is at least one element selected from the group consisting of cerium, yttrium, lanthanum, gadolinium and lutetium, and cerium is A phosphor containing at least one element selected from lead and tin. 2. The phosphor according to claim 1, wherein the total content of lead and tin with respect to 1 mol of the phosphor base is 0.1 gram atom or less.