JP2003105334A - Phosphor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chemically stable new phosphor which emits yellow light having high luminance under various excitation conditions, especially UV light excitation condition. SOLUTION: This phosphor comprises an aluminosilicate compound of the following composition formula having a nephelite type crystal structure activated with divalent europium. a(Na1-x-2y , Kx , Euy )2 O.bAl2 O3 .2SiO2 [(a), (b), (x) and (y) are the numbers of 0<=(x)<=0.8, 0.005<=(y)<=0.1, 0<(x)+2(y)<=0.8, 0.8<=(a)<=1.2, 0.8<=(b)<=1.2].

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a europium-activated oxide phosphor that emits yellow light with high brightness when excited by ultraviolet rays, vacuum ultraviolet rays, electron beams, and X-rays, and particularly ultraviolet rays, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, fluorescent materials are fluorescent lamps, CRTs and Ps.
It has been widely put to practical use for displays such as DPs, radiographic intensifying screens, and indoor and outdoor decorations. These phosphors emit near-ultraviolet light to visible light when excited by ultraviolet rays, vacuum ultraviolet rays, electron beams, and X-rays. The structure of these phosphors is such that a small amount of light emitting ions such as Eu and Mn are added to a base material crystal such as a metal oxide, a sulfide, an oxysulfide and a halide. Generally, phosphors are required to have various characteristics such as emission color, emission intensity, compatibility with excitation wavelength, stability, etc., but all of them are satisfied in the yellow light-emitting phosphor targeted by the present invention. There is nothing to do.

[0003]

DISCLOSURE OF THE INVENTION The present invention, under various excitations,
In particular, the present invention provides a novel chemically stable phosphor that emits yellow light with high brightness when excited by ultraviolet rays.

[0004]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have found that an oxide composed of sodium or sodium and potassium, aluminum or silicon and having a nepheline type crystal structure. It was found that a compound in which divalent europium was activated exhibited yellow emission, and the present invention was completed.

The present invention will be described in detail below.

The phosphor of the present invention is a phosphor composed of an aluminosilicate compound having a nepheline-type crystal structure activated by divalent europium, and is essentially composed of a compound having a nepheline structure. is there. Nepheline is a naturally occurring hexagonal compound with a typical composition of Na.
It is known that K replaces a part of the Na seat of AlSiO _{4 to form} a solid solution.

The phosphor of the present invention is represented by the following composition formula. a (Na _1-x-2y , K _x , Eu _y ) ₂ O ・ bAl ₂ O ₃・ 2S
iO ₂ (where a, b, x and y are respectively 0 ≦ x ≦ 0.
8, 0.005 ≦ y ≦ 0.1, 0 <x + 2y ≦ 0.8,
It is a number in the range of 0.8 ≦ a ≦ 1.2 and 0.8 ≦ b ≦ 1.2. ) The content of K in the phosphor of the present invention is preferably 0 ≦ x ≦ 0.8. Within this range, the predominant nepheline structure (Na _1-m ,
K _m ) AlSiO ₄ is produced, and yellow emission having a peak at 510 to 540 nm is exhibited by excitation with ultraviolet rays, electron beams, X-rays and the like. The emission peak wavelength shifts to the short wavelength side as the K amount increases.

When x exceeds 0.8, the nepheline structure (Na
_1-m , K _m ) AlSiO ₄ is hardly generated, and yellow luminescence is not observed, which is not preferable.

Further, even if 0 ≦ x ≦ 0.8, KA having a crystal structure different from nepheline in a region having a large K content.
lSiO ₄ is produced as a by-product, and a blue emission component of about 415 nm derived from this compound is mixed in the emission spectrum.

That is, brighter yellow emission is desired.
The range of x is 0 ≦ x ≦ 0.25,
preferable. In this range, K is a completely solid-solved compound,
(Na _1-m, K_m) AlSiO_FourIs obtained in almost a single phase,
High light efficiency and maximum emission wavelength of 510 to 540 nm
A yellow illuminant is obtained.

The preferable amount of Eu in this phosphor is 0.00.
5 ≦ y ≦ 0.1 and 0 <x + 2y ≦ 0.8.

If the Eu amount y is less than 0.005, sufficient light emission cannot be obtained due to insufficient Eu amount, which is not preferable.
On the other hand, when y exceeds 0.1, concentration quenching occurs, so that the luminous efficiency decreases, which is not preferable.

Also, x + 2y, which is the sum of the K amount and the Eu amount.
When the value exceeds 0.8, nepheline structure (Na _1-m , K _m ) AlS
It is not preferable because iO ₄ cannot be obtained.

The amount of alkali metal in this phosphor is 0.8 ≦
It is within the range of a ≦ 1.2. Within this range, (Na
_1-m , K _m ) AlSiO ₄ is mainly produced, and a yellow phosphor having high luminous efficiency is obtained.

If the amount of alkali metal a is less than 0.8, the amount of by-products produced increases and the luminous efficiency decreases, which is not preferable. Further, even if a exceeds 1.2, the amount of by-products generated increases and the luminous efficiency decreases, which is not preferable.

More preferably, the amount of alkali metal is 0.
9 ≦ a ≦ 1.1. Within this range, the nepheline structure (N
a _1-a , K _a ) AlSiO ₄ is produced in a substantially single phase, and a yellow phosphor having high luminous efficiency is obtained.

The amount of Al in this phosphor is 0.8 ≦ b ≦ 1.
It is within the range of 2. Within this range, (Na _1-m , K _m )
AlSiO ₄ is mainly produced, and a yellow phosphor with high luminous efficiency is obtained.

If the Al amount b is less than 0.8, the amount of by-products such as feldspars increases and the luminous efficiency decreases, which is not preferable. When b exceeds 1.2, free Al ₂ O ₃
Is increased, and the luminous efficiency is reduced, which is not preferable.

More preferably, the Al content is 0.9 ≦ b ≦
1.1. Within this range, the nepheline structure (Na _1-a ,
K _a ) AlSiO ₄ is produced in a substantially single phase, and a yellow phosphor having high luminous efficiency is obtained.

Next, an example of the method for producing the phosphor of the present invention will be described.

As the raw material of the phosphor of the present invention, an oxide, or a carbonate, a nitrate, a sulfate, a halide, a hydroxide or the like which easily becomes an oxide during the firing treatment can be used.

As the sodium raw material, for example, sodium carbonate, sodium hydrogen carbonate, sodium nitrate, and sodium alkoxide can be used.

As the potassium raw material, for example, potassium carbonate, potassium nitrate, potassium sulfate, and an alkoxide of potassium can be used.

As the aluminum raw material, for example, α-
Alumina, β-alumina, γ-alumina, aluminum hydroxide, aluminum nitrate, aluminum fluoride, and aluminum alkoxide can be used.

As the silicon raw material, for example, quartz, silicon dioxide such as cristobalite, and silicon alkoxide can be used.

As the europium raw material, for example, europium oxide, europium chloride or europium fluoride can be used.

A predetermined amount of these raw materials are weighed and mixed.
The mixing method may be either wet mixing or dry mixing.

Further, the raw materials can be prepared by utilizing a chemical reaction such as a sol-gel method and a coprecipitation method.

In order to promote the crystal growth and improve the emission brightness, 0.1 to 10% by weight of a phosphor material is used to melt a relatively low melting point compound such as an alkali metal halide or a boron compound. You may add and mix as an agent.

After the raw material mixture is dried, it is put in a heat-resistant container such as an alumina crucible and placed in an inert gas or a reducing atmosphere such as hydrogen gas at 1000 to 1500 ° C. for 1 to 5 ° C.
Bake for 0 hours. In particular, it is preferable to use an inert gas containing 1 to 5% by volume of hydrogen, because the activator Eu is favorably held in a divalent state and a phosphor having a high emission intensity is obtained. It is also effective to pulverize the obtained fired product and repeat the re-firing to obtain a uniform phosphor powder. In that case, a reducing atmosphere may be used in the final firing.

In the composition range of the present invention, it is known that high-temperature type Carnegieite is stable at about 1255 ° C. or higher, but most of them are reversibly converted to nepheline during the cooling process after firing. Since the phase transition occurs, no particular problem occurs if the firing temperature is selected within the above range.

Next, the phosphor of the present invention can be obtained by crushing, washing with water, drying, and sieving, if necessary, to adjust the purity and particle size of the fired product.

[0033]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. (1) Crystal structure The crystal structure of the powder was identified by a powder X-ray diffractometer (MPX3 manufactured by Mac Science Co.). Cu as an X-ray source
-Kα radiation was used. (2) Fluorescence evaluation Fluorescence evaluation was measured by a fluorescence spectroscopy evaluation device manufactured by JASCO Corporation. Excitation wavelength is 254 nm, 300 to 780 nm
The emission spectrum up to was measured. Also, the excitation wavelength is 2
The excitation spectrum from 20 to 400 nm was measured.

(Example 1) NaHCO ₃ 5.75 g Al ₂ O ₃ 3.56 g SiO ₂ 4.20 g Eu ₂ O ₃ 0.12 g The above raw materials were weighed and mixed as phosphor raw materials. This mixture was placed in an alumina container, introduced into an electric furnace,
12 in an atmosphere of nitrogen gas containing ol% hydrogen gas
It was baked at 00 ° C. for 6 hours.

The fired product was crushed to have a composition of Na _0.98 Eu.
A phosphor of _0.01 AlSiO ₄ was obtained. The result of powder X-ray diffraction of the obtained phosphor is shown in FIG. 1 (the pattern marked with 1 in the lower part of FIG. 1). It was confirmed that the obtained phosphor had a hexagonal nepheline structure.

The emission spectrum of 254 nm ultraviolet excitation is shown in FIG. 2 (the curve labeled 1 in FIG. 2). 53
Yellow emission having an emission peak at 8 nm was exhibited.

FIG. 3 shows an excitation spectrum at an emission wavelength of 538 nm. Excitation is efficiently performed by ultraviolet rays in a wide wavelength range from 220 to 400 nm.

(Example 2) NaHCO ₃ 4.02 g K ₂ CO ₃ 1.21 g Al ₂ O ₃ 3.44 g SiO ₂ 4.07 g Eu ₂ O ₃ 0.24 g The above raw materials were weighed as phosphor raw materials, Mixed. This mixture was placed in an alumina container, introduced into an electric furnace,
13 in an atmosphere of nitrogen gas containing ol% hydrogen gas
It was baked at 00 ° C. for 6 hours.

The fired product was crushed to have a composition of Na _0.71 K.
A phosphor of _0.25 Eu _0.02 AlSiO ₄ was obtained.

The powder X-ray diffraction result of the obtained phosphor is shown in FIG.
(The pattern marked with 2 in the upper part of FIG. 1). It was confirmed that the obtained phosphor had a hexagonal nepheline structure.

The emission spectrum of 254 nm ultraviolet excitation is shown in FIG. 2 (curve marked with 2 in FIG. 2). 53
Yellow emission having an emission peak at 5 nm was exhibited.

Further, in the excitation spectrum measurement at the emission wavelength of 535 nm, it was found that the excitation was efficiently performed by the ultraviolet light having a wide wavelength range from 220 to 400 nm.

[0043] (Example 3) as _{NaHCO 3 2.45g K 2 CO 3 2.08g} Al 2 O 3 2.97g SiO 2 3.90g Eu 2 O 3 0.57g phosphor materials were weighed each raw material, Mixed. This mixture was placed in an alumina container, introduced into an electric furnace,
13 in an atmosphere of nitrogen gas containing ol% hydrogen gas
It was baked at 00 ° C. for 6 hours.

The calcined product was crushed to have a composition of Na _0.45 K.
A phosphor of _0.45 Eu _0.05 Al _0.9 SiO _3.85 was obtained.

It was confirmed by powder X-ray diffraction that the obtained phosphor had a hexagonal nepheline structure.

The emission spectrum of 254 nm ultraviolet ray excitation is shown in FIG. 2 (the curve labeled 3 in FIG. 2). 52
It exhibited yellow emission having an emission peak at 0 nm.

Also, in the excitation spectrum measurement at the emission wavelength of 535 nm, it was found that the excitation was efficiently performed by the ultraviolet light having a wide wavelength range from 220 to 400 nm.

(Example 4) NaHCO ₃ 1.08 g K ₂ CO ₃ 3.58 g Al ₂ O ₃ 3.60 g SiO ₂ 4.26 g Eu ₂ O ₃ 0.11 g H ₃ BO ₃ 0.20 g As a phosphor raw material The above raw materials were weighed and mixed. This mixture was placed in an alumina container, introduced into an electric furnace,
14 in an atmosphere of nitrogen gas containing ol% hydrogen gas
It was baked at 00 ° C. for 2 hours.

The fired product was crushed to have a composition of Na _0.2 K.
A phosphor of _0.78 Eu _0.01 Al _1.1 Si _1.1 O _4.35 was obtained.

It was confirmed by powder X-ray diffraction that the resulting phosphor had a hexagonal nepheline structure.

The emission spectrum of 254 nm ultraviolet light excitation is shown in FIG. 2 (curve labeled 4 in FIG. 2). 51
Yellow emission having an emission peak at 5 nm was exhibited.

Further, in the excitation spectrum measurement at the emission wavelength of 535 nm, it was found that the excitation was efficiently performed by the ultraviolet light having a wide wavelength range from 220 to 400 nm.

(Example 5) Thermal stability test The phosphors of Examples 1 to 4 were placed in an alumina container and introduced into a box-type electric furnace. It was kept at 600 ° C. for 2 hours in the air atmosphere. The emission characteristics of the phosphor after this heat treatment were evaluated. 25
It was confirmed that the emission intensity due to 4 nm ultraviolet excitation did not change from that before the heat treatment and was stable to the heat treatment.

[0054]

According to the present invention, it is possible to provide a novel yellow light-emitting oxide phosphor having high efficiency and excellent chemical stability.

[Brief description of drawings]

FIG. 1 shows X of phosphor powders obtained in Examples 1 and 2.
It is a figure which shows a line diffraction.

FIG. 2 shows 254 of the phosphor powder obtained in Examples 1 to 4.
It is a figure which shows the emission spectrum by ultraviolet excitation of nm.

FIG. 3 is a diagram showing an excitation spectrum of 535 nm emission of the phosphor powder obtained in Example 1.

Claims (3)

[Claims] 1. A phosphor comprising an aluminosilicate compound having a nepheline-type crystal structure activated by divalent europium. 2. The phosphor according to claim 1, which is represented by the following composition formula. a (Na _1-x-2y , K _x , Eu _y ) ₂ O ・ bAl ₂ O ₃・ 2S
iO ₂ (where a, b, x and y are respectively 0 ≦ x ≦ 0.
8, 0.005 ≦ y ≦ 0.1, 0 <x + 2y ≦ 0.8,
It is a number in the range of 0.8 ≦ a ≦ 1.2 and 0.8 ≦ b ≦ 1.2. ) 3. The phosphor according to claim 2, wherein the range of x is 0 ≦ x ≦ 0.25.