JPH01165689A - Phosphor - Google Patents

Abstract

PURPOSE:To prepare a Tb-activated rare earth phosphate phosphor capable providing a fluorescent lamp excellent in the brightness, the lamp beam and lamp maintenance, by adding Pb and/or Sn to a particular matrix. CONSTITUTION:At least one compd. (i) selected from among Y2O3, La2O3, Gd2O3 and Lu2O3 is mixed with CeO2 (ii), Tb4O7 (iii) and at least one compd. (iv) selected from (NH4)H2PO4 and (NH4)2HPO4, PbO (v) and SnO2 (vi). The mixture is baked once or twice in a neutral or reducing atmosphere at 700-1300 deg.C for 2-5hr to prepare a baking product. The baking product is pulverized, washed, dried, and sieved io prepare a phosphor of formula II (wherein 0<a+b<=0.1) wherein the total content of Pb and Sn is 10<-6>-10<-1> gram atom based on 1mol of a phosphor matrix of formula I (wherein Ln is a rare earth element selected from among Y, La, Gd, and Lu; and 0 (x+y<=1).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a phosphor, and more particularly to a rare earth phosphate phosphor containing terbium as an activator.

[Prior Art] Terbium-activated yttrium silicate phosphor (Y25i) has conventionally been used as a green-emitting phosphor using a rare earth element as an activator.
ns:Tb) and terbium-activated lanthanum phosphate phosphors (LaPOs:Tb), cerium and terbium-activated yttrium silicate phosphors (Y2SiO5:Cc, 'rb), and cerium and terbium-activated lanthanum phosphate phosphor (L ; x P
04:Cc, Tb) which use cerium and terbium as activators are known. Since these phosphors have a very narrow lower range of emission spectrum, they have characteristics suitable for a three-wavelength lamp with high color rendering properties. In particular, cerium- and terbium-activated lanthanum phosphate phosphors are widely used as green-emitting phosphors for three-wavelength lamps because of their high efficiency and low manufacturing costs.

Further, in order to improve the characteristics of rare earth phosphate phosphors using cerium and terbium as activators, it has been proposed to add various other components.

For example, Japanese Patent Application Laid-Open No. 57-133182 discloses that an alkali metal element is added.
No. 3 discloses the addition of hafnium and/or zirconium, JP-A No. 59-129287 discloses the addition of magnesium, and JP-A No. 62-897 discloses the addition of magnesium.
Publication No. 90 describes the addition of Amp-Mon.

The purpose of the present invention is to improve the characteristics of a rare earth phosphate phosphor using terbium as an activator, and in particular to improve the brightness by using a new additive, and to improve the brightness of a fluorescent lamp using the phosphor. The objective is to improve the luminous flux of the lamp and improve the luminous flux maintenance rate.

[Summary of the Invention] According to the present invention, the above object is achieved by using a rare earth phosphate phosphor containing terbium as an activator (
Here, the rare earth is at least one element selected from the group consisting of cerium, yttrium, lanthanum, gadolinium, and lutetium, and cerium is essential,
(the same shall apply hereinafter), characterized in that it contains at least one element of lead and tin,
is provided.

The phosphor according to the present invention can be expressed, for example, by the following compositional formula: Ln Ce Tb PO・aPh, bSnl-x-
Y
+b≦0.1 and O<x+y≦1) In other words, LnCeTbPO is used as a matrix, and Pb and l-4-y x y 4 and/or Sn are added thereto. is an essential requirement.

The phosphor of the present invention emits high-intensity green light when excited by ultraviolet light with a wavelength of 253.7 nm, and can provide a fluorescent lamp with high initial brightness and good lamp luminous flux and luminous flux maintenance rate.

In view of such effects, in the phosphor according to the present invention, the total of the PB content and Sn content per mole of the phosphor matrix is preferably 10-6 to 10-1 gram atoms, and 1O-5 to 10-1 gram atoms. More preferably, it is 2 gram atoms.

The phosphor according to the present invention may further contain a small amount of other components, if necessary or unavoidably mixed. For example, antimony (sb
) may be included, thereby making it possible to modify the luminance and luminous flux maintenance factor.

The content of sb is 10-6 to 10 per mole of phosphor matrix.
″″3 gram atoms are recommended.

The present invention will be explained in more detail below.

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

First, as a raw material for phosphor, (a) Il[! Yttrium dioxide (Y203), oxidation rank: / (1, a203), gadolinium oxide (G
d203), and lutetium oxide (Lu203)
The first group of compounds consisting of
3,1,a203, Gci203, L, u203
a second compound group consisting of yttrium compounds, lanthanum compounds, gadolinium compounds, and lutetium compounds that can be converted into cerium oxide (Ce203); At least one compound selected from the group of compounds consisting of convertible cerium compounds; (c) At least one compound selected from the group consisting of terbium oxide ('b407) and terbium compounds that can easily convert to Tb4O7 at high temperatures. .

(d) Ammonium monophosphate ((NH4)02PO4
) and diammonium phosphate ((NH4)28PO4
) and a second compound group that can easily become a phosphoric acid source at high temperatures; (e) lead oxide (PbO); At least one compound selected from the group of compounds consisting of lead compounds that can be converted into PbO, and (to) tin oxide (SnO2) and Sn that easily converts into PbO at high temperatures.
or (i) yttrium, lanthanum, or gadolinium.

Co-precipitated oxide of at least one kind of lutetium and terbium and cerium, (b) monoammonium phosphate ((NH4)H2PO4
) and diammonium phosphate ((NH4)28PO4
) and a second compound group that can easily become a phosphoric acid source at high temperatures; (c) lead oxide (pbo) and At least one compound selected from the group of compounds consisting of lead compounds that can be converted into PbO, and (d)tin oxide (SnO2) and 5n02 that can be easily converted to PbO at high temperatures.
At least one compound selected from the group of compounds consisting of tin compounds that can be used can be used.

The above-mentioned phosphor raw materials are, for example, Ln Ce Tb PO・aPb, bSnl-x-
y x y 4゜ (wherein Ln is at least one selected from the group consisting of yttrium, lanthanum, gadolinium, and lutetium)
It is a rare hepta element of species, a, b, x and y are O<a+b
≦0.1 and O<x+y≦1) Required amounts of each are weighed out and mixed in seven parts so as to satisfy the mixing composition formula: The mixing may be carried out dry using a ball mill, mixer mill, mortar, etc., or may be carried out wet by forming a paste using water or the like as a medium.

Next, the phosphor raw material mixture is filled into a heat-resistant container such as an alumina crucible or a quartz crucible, and fired. Firing is performed at approximately 700°C in a neutral atmosphere such as air, argon gas atmosphere, nitrogen gas atmosphere, or a reducing atmosphere such as nitrogen gas atmosphere containing a small amount of hydrogen gas or carbon gas atmosphere.
This is carried out once or twice at a temperature of 1300°C to 1300°C. 2
When performing multiple firings, after the first firing is completed, the phosphor mixture is returned to room temperature, and if necessary, the mixture is loosened and then fired again.

During firing, in order to ensure that the valence of terbium and cerium is trivalent, at least the final firing (or the first firing in the case of one firing) is performed in a neutral or reducing atmosphere. It is preferable to do so. The firing time varies depending on the weight of the phosphor raw material mixture filled in the heat-resistant container, but generally within the above firing temperature range
5 hours is appropriate. Incidentally, if a compound of an alkali metal element, a boron compound, or the like is used as a flux to accelerate the reaction during firing, firing at a lower temperature and for a shorter time becomes possible.

After firing, the phosphor of the present invention can be obtained by processing the obtained fired product through various operations generally employed in the production of phosphors, such as crushing, washing, drying, and sieving.

As described above, the phosphor of the present invention emits high-intensity green light when excited by ultraviolet rays or the like, and therefore has versatility in various lamps mainly having a green light-emitting component.

[Example] The present invention will be explained below with reference to Examples.

In the examples, the relative brightness was measured by measuring the powder brightness of the obtained phosphor under ultraviolet light with a wavelength of 253.7 nm, and measurements of lamp luminous flux and luminous flux maintenance rate were not previously obtained. A 40 W fluorescent lamp was prepared using the phosphor, and the luminous flux 100 hours after the lamp was turned on was taken as the initial luminous flux, and the ratio of the luminous flux after 1000 hours to the initial luminous flux was measured as the luminous flux maintenance rate.

Examples 1-4: La%Ce as La source, Ce source, and Tb source.

Co-precipitated oxide of Tb, (NH4)28PO as phosphate source
4. Weigh out PBO as a Pb source so that it has a stoichiometrically predetermined mixed composition formula, mix thoroughly, then put the mixed powder into an aluminium crucible and heat it in air at 700°C for 2 hours. Calcined. After cooling to room temperature, the fired product was pulverized, put into a quartz crucible again, fired at 1200°C for 2 hours in a reducing atmosphere, and subjected to prescribed treatments to obtain Examples 1 to 4 in Table 1.
A phosphor as shown in was manufactured. At the same time, for comparison, a phosphor was also produced in the same manner, except that it did not contain PB (comparative example).

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

As shown in Table 1, the Pb-containing phosphor has better overall characteristics than the comparative example.

Examples 5 to 8: Co-precipitated oxide of La, Ce, and Tb as a La source, Ce source, and Tb source, (Nf+4)zIll'''04 as a phosphoric acid source
．． 5n02 was chemically weighed out as a Sn source so that it would have a predetermined mixed composition formula, and then phosphors as shown in Examples 5 to 8 in Table 1 were prepared in the same manner as Examples 1 to 4 above. manufacture,
Characteristics were measured.

As shown in Table 1, the Sn-containing phosphor has better overall characteristics than the comparative example.

Examples 9 to 11: 1-5a source, Ce source, Tb source: 1. ,a,ce,′
Co-precipitated oxide of “b, (NH4)211P as a phosphoric acid source
O4, Y2 o3 as Y source, Gd20 as Gd source
3, Lu203 as a Lu source, Pb as a Pb source
O was weighed out so as to have a stoichiometrically predetermined mixed composition formula, and the following procedure was carried out in the same manner as in Examples 1 to 4 above to prepare Example 9 in Table 1.
Phosphors as shown in ~11 were manufactured and their characteristics were measured.

As shown in Table 1, the phosphors in which part of %La was replaced with f6 by Y, Gd, or [-u also had overall improved characteristics compared to the comparative example.

Example 12.13: La%Ce as La source, Ce source, and Tb source.

Co-precipitated oxide of Tb, (NH4)28PO as phosphate source
4. PbO as a Pb source and 5n02 as a Sn source were weighed out so as to stoichiometrically give a predetermined mixed composition formula, and the following was carried out in the same manner as Examples 1 to 4 above to prepare Example 12.13 in Table 1. A phosphor as shown in the figure was manufactured and its characteristics were measured.

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

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

Procedural amendment February 24, 1988 Kunio Ogawa, Director-General of the Fraud Office 1 Indication of the case Patent application No. 1983-323673 2 Name of the invention Phosphor 3 Relationship with the weakness of the person making the amendment Name of patent applicant Kasei Opto Nix Co., Ltd. 4 Agent address: 40 Toranomon, 5-13-1 Toranomon, Minato-ku, Tokyo
Detailed description of the invention column 6 in the Mori Building specification Contents of amendment (1) rce20 on page 6 lines 12 and 13 of the specification
Correct all 3J to rce02J.

(2) “Single hour” in the first line of page 10 of the specification is “short time”
I am corrected.

Claims (2)

[Claims] (1) Rare earth phosphate phosphor containing terbium as an activator (here, rare earth is at least one element selected from the group consisting of cerium, yttrium, lanthanum, gadolinium, and lutetium, and cerium is essential) A phosphor comprising at least one element selected from lead and tin. (2) Claim 1, wherein the total content of lead and tin per mole of the phosphor matrix is 0.1 gram atom or less.
Phosphor described in section.