JP2995976B2 - Method for producing green light emitting phosphor for lamp - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a process for producing a green-emitting rare earth phosphate phosphor co-activated with lanthanum and terbium .
Construction method .

[0002]

2. Description of the Related Art Cerium and terbium co-activated phosphate phosphors are widely used as green light-emitting phosphors for three-wavelength fluorescent lamps. It is also used as a fluorescent lamp for a light source of a copying machine. When this phosphor is used for these applications, it is important to reduce the decrease in the luminous flux maintenance factor in addition to increasing the initial luminous flux. When a green light-emitting phosphor having a low luminous flux maintenance ratio is used for a three-wavelength fluorescent lamp,
The emission color of the fluorescent lamp changes gradually. The reason is that the three-wavelength fluorescent lamp initially emits white light with the color balance of the red, blue, and green light-emitting phosphors. There is a problem that the luminous color shifts due to a high luminous luminance. For this reason, when a plurality of three-wavelength fluorescent lamps are used in close proximity, the new fluorescent lamp and the old fluorescent lamp emit different colors, so it is necessary to replace all the fluorescent lamps at the same time.

Further, in the three-wavelength fluorescent lamp, the ratio of the green light-emitting phosphor to the total luminous flux is very high. Therefore, if a green light-emitting phosphor having excellent characteristics is developed, the characteristics of a three-wavelength fluorescent lamp can be significantly improved.

Further, when the brightness of a fluorescent lamp used as a light source of a copying machine decreases, the amount of exposure changes, so that it is necessary to adjust the density as it is used. There is also a disadvantage that copying with excellent contrast cannot be performed.

Conventionally used cerium and terbium co-activated phosphate phosphors do not have satisfactory emission characteristics when used in these applications. In particular, this phosphor shows a metal material in the composition formula (Re
And _{1-x-y Ce x Tb} y), 1 molar ratio of phosphate PO ₄ precisely: it is difficult to manufacture as 1. When a mixture of a metal material and a raw material to be phosphoric acid is mixed at a molar ratio of 1: 1 and fired, a phosphor having extremely low emission luminance may be obtained. In order to avoid this disadvantage, phosphors are fired by adding a phosphoric acid raw material in a somewhat larger amount than a metal material.

[0006] The phosphor thus manufactured has a drawback that the luminous flux maintenance factor is low when used in a fluorescent lamp. It is considered that phosphoric acid added in a richer manner than the metal component reacts with Hg vapor inside the fluorescent lamp and sodium in the glass tube to form amalgam, which lowers light emission luminance.

Phosphors which improve these conventional cerium and terbium co-activated phosphate phosphors are disclosed in JP-B-60-95.
No. 43 is described. This publication describes a phosphor represented by the following composition formula. _{(Re 1-a-b Ce} b Tb a) 2 O 3 · xSiO 2 ·
yP ₂ O ₅ .zAl ₂ O ₃ This phosphor is obtained by adding silica and alumina to a cerium / terbium co-activated phosphate phosphor.

Further, JP-A-3-167289 describes a cerium / terbium co-activated phosphate phosphor represented by the following composition formula. _{(Re 1-a-b-} c Ce b Tb a Tm c) 2 O 3 · x
SiO ₂ .yP ₂ O ₅ .zAl ₂ O ₃ The phosphor represented by this composition formula is obtained by further adding Tm to the aforementioned phosphor.

[0009]

The cerium and terbium co-activated phosphate phosphors described in these publications realize excellent light emission characteristics as compared with conventional phosphors.
However, the phosphors described in these publications cannot be used in three-wavelength fluorescent lamps or copiers to exhibit sufficiently satisfactory emission characteristics.

The present invention has been developed with the aim of realizing a more excellent green light-emitting phosphor. An important object of the present invention is to improve the initial light emission output in addition to the excellent luminous flux maintenance factor. It is an object of the present invention to provide a method of manufacturing a green light emitting phosphor for a lamp.

[0011]

Means for Solving the Problems] In the method of the present invention are prepared
The green light-emitting phosphor is represented by the following composition formula, and x, y,
z is specified in the following range. (Re _1-xy Ce
However _{x Tb y) PO 4 · zR} 2 O 3, In this composition formula, Re is chosen Y, Gd, at least one member selected from among La, R is Y, Gd, La, Ce, from among Tb At least one type.

That is, the cerium and terbium co-activated phosphate phosphor of this composition is a conventional (ReCeTb) P
An oxide of any of the rare earth elements Y, Gd, La, Ce, and Tb represented by R in the composition formula is added to the O ₄ phosphor.
It is fired . The phosphor of the present invention comprises (ReC
against ETB) PO _4, 0.06 moles of rare earth oxide added, a metal material quantity, by greater than PO ₄ weight PO ₄ in lamps, reacts with Hg and Na amalgam It is intended to prevent from becoming. The amount of the rare earth oxide represented by R is limited to 0.06 mol or less. This is because the addition of more than this lowers the emission luminance of the phosphor.

The cerium and terbium co-activated phosphate phosphors produced by the method of the present invention also have a high emission luminance by limiting the amount of cerium and terbium added to a specific range. doing.

[0014]

Embodiments of the present invention will be described below. However,
The examples described below illustrate phosphors embodying the technical idea of the present invention, and the phosphors of the present invention do not specify the manufacturing method, raw materials, and the like as follows. The present invention can have various modifications within the scope of the claims.

Example 1 A cerium and terbium co-activated phosphate green light-emitting phosphor is manufactured as follows. The following materials are sufficiently pulverized and mixed by a ball mill or the like. CeO ₂ = 0.27 mol La ₂ O ₃ = 0.30 mol Tb ₄ O ₇ = 0.0325 mol (NH ₄ ) ₂ HPO ₄ = 1.0 mol The obtained mixture was packed in a crucible and heated at 1200 ° C. Bake for 3 hours in a reducing atmosphere. Thus, a conventional cerium / terbium co-activated phosphate phosphor represented by the following composition formula is obtained. (La _0.60 Ce _0.27 Tb _0.13 ) PO ₄

[0016] La ₂ O ₃ was added to the obtained fired product in an amount of 0.
Add 02 mol and pulverize and mix well with a ball mill etc.
Baking is performed for 3 hours in a reducing atmosphere at 1250 ° C. Thus, a cerium / terbium co-activated phosphate green light-emitting phosphor represented by the following composition formula can be obtained. (La _0.60 Ce _0.27 Tb _0.13 ) PO _4.
0.02La ₂ O ₃

The thus-produced rare earth green light-emitting phosphor in which cerium and terbium are co-activated emits strong green light having an emission peak wavelength near 545 nm when excited by ultraviolet light.

Using this phosphor, a 40-watt fluorescent lamp FL40SS was manufactured, and the light emission output (total luminous flux) was measured. The measurement time was evaluated immediately after fabrication and after lighting for 1000 hours. The luminous flux of the phosphor of the present invention immediately after the production of the fluorescent lamp is
102.8%, and the luminous flux maintenance factor after lighting for 1000 hours was 96.8%.

However, the emission luminance is the same as that of the conventional (La
_0.60 Ce _0.27 Tb _0.13 ) The initial emission output of the fluorescent lamp using the PO ₄ phosphor is shown as 100%. Fluorescent lamps using conventional phosphors are:
The luminous flux maintenance ratio after lighting for 000 hours was 92.3%.

As described above, the fluorescent lamp using the phosphor obtained in Example 1 has an excellent luminous flux maintenance ratio and a high initial luminous output, exhibits excellent luminous characteristics, and emits light remarkably as compared with conventional products. The characteristics have improved.

[Examples 2 to 4] In Example 1, a green light-emitting phosphor having the following composition formula was produced by changing the second amount of La ₂ O ₃ introduced. (La _0.60 Ce _0.27 Tb _0.13 ) PO ₄ .Z
La ₂ O _{3 In} this composition formula, the raw materials to be added are adjusted so that Z = 0.01 in Example 2, z = 0.03 in Example 3, and z = 0.04 in Example 4. I do. The manufacturing process is the same as in the first embodiment. Table 1 shows the characteristics of the fluorescent lamp thus manufactured.

[0022]

[Table 1]

Example 5 A cerium / terbium co-activated phosphate green light-emitting phosphor is manufactured as follows. The following materials are sufficiently pulverized and mixed by a ball mill or the like. CeO ₂ = 0.27 mol Y ₂ O ₃ = 0.30 mol Tb ₄ O ₇ = 0.0325 mol (NH ₄ ) ₂ HPO ₄ = 1.0 mol The obtained mixture was packed in a crucible and heated at 1200 ° C. Bake for 3 hours in a reducing atmosphere. In this way, a conventional cerium and terbium co-activated phosphate phosphor was obtained, and
Then, Y ₂ O ₃ was used in place of La ₂ O ₃ in the above embodiment.
Cerium, terbium represented by the following composition formula
To obtain a phosphor co-activated phosphor green light emitting phosphor. (Y _0.60
Ce _0.27 Tb _0.13 ) PO ₄ 0.02 Y ₂ O ₃ Table 2 shows the characteristics of the fluorescent lamp using the phosphor thus manufactured.

Example 6 A cerium / terbium co-activated phosphate green light-emitting phosphor is manufactured by the following method. The following materials are sufficiently pulverized and mixed by a ball mill or the like. CeO ₂ = 0.27 mol Gd ₂ O ₃ = 0.30 mol Tb ₄ O ₇ = 0.0325 mol (NH ₄ ) ₂ HPO ₄ = 1.0 mol The obtained mixture was packed in a crucible and heated at 1200 ° C. Bake for 3 hours in a reducing atmosphere. In this way, a conventional cerium and terbium co-activated phosphate phosphor was obtained, and
In the _Gd 2 _{O 3} in place of _La 2 _{O 3} in the illustrated embodiments
Cerium, terbium represented by the following composition formula
To obtain a phosphor co-activated phosphor green light emitting phosphor. (Gd
_{0.60 Ce 0.27 Tb 0.13) PO 4} · 0.02
Gd ₂ O ₃ Table 2 shows the emission characteristics of the fluorescent lamp using the cerium and terbium co-activated phosphate phosphor thus obtained.

[0025]

[Table 2]

In this table, the total luminous flux after the production of the lamp is illustrated as a conventional example in Example 1 (La
The initial luminous flux of a fluorescent lamp using _0.60 Ce _0.27 Tb _0.13 ) PO ₄ phosphor is set to 100%.
The total luminous flux after 1000 hours is 100% of the initial luminous flux.
And

Example 7 In the same manner as in Example 1, a terbium co-activated phosphate green light-emitting phosphor having the following composition formula is produced. (La _0.60 Ce _0.27 Tb _0.13 ) PO ₄ 0.02 mol of Y ₂ O ₃ was added to the obtained calcined product, and the mixture was sufficiently pulverized and mixed by a ball mill or the like. Bake for hours. Thus, a cerium / terbium co-activated phosphate green light-emitting phosphor represented by the following composition formula can be obtained. (La _0.60 Ce _0.27 Tb _0.13 ) PO _4.
The characteristics of the fluorescent lamp using 0.02Y ₂ O ₃ resulting phosphor is shown in Table 3.

Example 8 In the same manner as in Example 1, a terbium co-activated phosphate green light-emitting phosphor having the following composition formula is produced. (La _0.60 Ce _0.27 Tb _0.13 ) PO ₄ 0.02 mol of Gd ₂ O ₃ was added to the obtained calcined product, and the mixture was sufficiently pulverized and mixed by a ball mill or the like. Bake for 3 hours. Thus, a cerium / terbium co-activated phosphate green light-emitting phosphor represented by the following composition formula can be obtained. (La _0.60 Ce _0.27 Tb _0.13 ) PO _4.
Table 3 shows the characteristics of the fluorescent lamp using the obtained phosphor of 0.02 Gd ₂ O ₃ .

Example 9 In the same manner as in Example 1, a terbium co-activated phosphate green light-emitting phosphor having the following composition formula is produced. (La _0.60 Ce _0.27 Tb _0.13 ) PO _{4 To the} obtained fired product, 0.02 mol of Ce ₂ O ₃ was added, and the mixture was sufficiently pulverized and mixed by a ball mill or the like. Bake for 3 hours. Thus, a cerium / terbium co-activated phosphate green light-emitting phosphor represented by the following composition formula can be obtained. (La _0.60 Ce _0.27 Tb _0.13 ) PO _4.
The characteristics of the fluorescent lamp using 0.02Ce ₂ O ₃ resulting phosphor is shown in Table 3.

Example 10 In the same manner as in Example 1, a terbium co-activated phosphate green light-emitting phosphor having the following composition formula is produced. (La _0.60 Ce _0.27 Tb _0.13 ) PO ₄ 0.01 mol of Ce ₂ O ₃ and T
0.01 mol of b ₂ O ₃ is added, pulverized and mixed sufficiently by a ball mill or the like, and calcined in a reducing atmosphere at 1250 ° C. for 3 hours. Thus, a cerium / terbium co-activated phosphate green light-emitting phosphor represented by the following composition formula can be obtained. (La _0.60 Ce _0.27 Tb _0.13 ) PO _4.
Table 3 shows the characteristics of a fluorescent lamp using the phosphor obtained. 0.01 Ce ₂ O ₃ .0.01 Tb ₂ O ₃

Example 11 In the same manner as in Example 1, a terbium-co-activated phosphate green light-emitting phosphor having the following composition formula was produced. (La _0.60 Ce _0.27 Tb _0.13 ) PO ₄ 0.01 mol of La ₂ O ₃ was added to the obtained calcined product,
0.01 mol of e ₂ O ₃ and 0.01 mol of Tb ₂ O ₃ are added, pulverized and mixed sufficiently by a ball mill or the like, and calcined in a reducing atmosphere at 1250 ° C. for 3 hours. Thus, a cerium / terbium co-activated phosphate green light-emitting phosphor represented by the following composition formula can be obtained. _{(La 0.60 Ce 0.27 Tb 0.13)} PO 4 · 0.
01La ₂ O ₃ .0.01 Ce ₂ O ₃ .0.01 Tb ₂ O ₃ Table 3 shows the characteristics of the fluorescent lamp using the obtained phosphor.

[0032]

[Table 3]

[0033]

Green-emitting phosphor for a lamp made by the method of the present invention exhibits, conventional cerium initial light emission output, 1-5% compared to the terbium co-activated phosphate phosphor improved Further, the light emission output after 1000 hours from the initial light emission output can be set to an extremely excellent characteristic of 92.6% to 97.3%. <br/> green luminous body produced by the method of the present invention, exhibit such excellent luminous flux maintenance _factor, the phosphor represented by _{(Re 1-x-y Ce} x Tb y) PO 4 By adding a rare earth oxide, phosphoric acid-rich state can be eliminated, and the reaction of phosphoric acid with Hg or Na to form amalgam can be effectively prevented.

Continuation of the front page (72) Inventor Keiji Ichinomiya 491-1, Kaminakamachioka, Anan-shi, Tokushima Prefecture Inside Nichia Chemical Industry Co., Ltd. (56) References JP-A-59-179578 (JP, A) (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C09K 11/81 H01J 61/44

Claims (1)

(57) [Claims] 1. A composition formula _{(Re 1-x-y Ce} x Tb y)
PO ₄ .zR ₂ O ₃ (where Re is Y, Gd, La)
At least one kind selected from among them, R is Y, Gd, L
at least one selected from a, Ce, and Tb
X, y, z are respectively 0.01 ≦ x ≦ 0.71,
Values in the range of 0.01 ≦ y ≦ 0.30, 0 <z ≦ 0.06
Wherein the phosphor raw material is calcined to obtain a composition formula (Re _1-xy Ce).
relative to 1 mol of the phosphor represented by _x Tb _y) PO _4,
0.06 mol or less of rare earth oxide (R ₂ O ₃ )
For firing in a reducing atmosphere
A method for producing a green light emitting phosphor.