JP2003277749A - Divalent metal silicate phosphor, phosphor paste composition and vacuum ultraviolet-excited light- emitting element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a blue light-emitting silicate phosphor improved in emission luminance, a phosphor paste and a vacuum ultraviolet-excited light-emitting element improved in luminance. <P>SOLUTION: The silicate phosphor comprises Ca, Eu, Mg, Si and La, and is represented by the formula: (Ca<SB>1-x</SB>Eu<SB>x</SB>)O aMgO bSiO<SB>2</SB>cLa<SB>2</SB>O<SB>3</SB>(wherein a, b, c and x satisfy 0.9≤a<1.1, 1.9≤b≤2.2, 0<c≤2.5×10<SP>-2</SP>, and 5×10<SP>-3</SP>≤x≤0.1, respectively). The phosphor paste composition comprises the phosphor. The vacuum ultraviolet-excited light-emitting element is provided with a phosphor film comprised of the phosphor. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention has a wavelength of 200 nm.
The following divalent metal silicate phosphor that emits blue light when excited by vacuum ultraviolet (VUV), a phosphor paste composition containing this phosphor, and a vacuum ultraviolet excited light emitting device equipped with a phosphor film using the same ( VUV excitation light emitting device)
Regarding

[0002]

2. Description of the Related Art In recent years, Ar, Xe, and H are typified by, for example, rare gas lamps and plasma display panels (PDPs) used as light sources for reading in scanners.
A rare gas such as e, Ne or Xe-Ne is enclosed in an envelope formed of glass or the like, and the VUV emitted by the discharge of the rare gas is a fluorescent film made of a VUV phosphor inside the envelope. Development of a VUV-excited light-emitting device having a structure that excites and emits light has been actively conducted.

A rare gas lamp, which is a typical example of a VUV-excited light-emitting device, has a glass narrow tube filled with a rare gas such as Xe or Xe-Ne, and the inner wall surface of the tube is excited by VUV. A fluorescent film made of a VUV fluorescent substance that emits light is formed. When electrical energy is applied between the electrodes of the rare gas lamp, a rare gas discharge occurs in the glass thin tube, and the VUV emitted at that time excites the fluorescent film formed on the inner wall surface of the tube to emit visible light. .

In principle, the PDP, which is another typical example of the VUV-excited light-emitting device, has the above-mentioned VUV-excited rare gas lamp further reduced in size, and a plurality of rare gas lamps are arranged in a stripe pattern or a matrix pattern. You can think of it as something. That is, the narrow discharge spaces (cells) are arranged in a stripe shape or a matrix shape.
An electrode is provided in each cell, and a VU is provided inside each cell.
A fluorescent film made of a V phosphor is formed. Noble gases such as Xe and Xe-Ne are enclosed in each cell, and when electric energy is applied from the electrodes in the cells, noble gas discharge occurs in the cells and VUV is radiated. The fluorescent film is excited to emit visible light, and the light emission causes an image to be displayed. V for full color PDP
Full-color display can be performed by arranging the cells made of phosphors that emit red, blue, and green by UV excitation in a stripe shape or a matrix shape.

As a phosphor for forming a phosphor film of these VUV-excited light-emitting devices, (Y, Gd) BO _{3 is} :
Red light-emitting phosphor such as Eu, LaPO ₄ : Ce, Tb,
(Ba, Sr) MgAl ₁₀ O ₁₇ : Eu, Mn, Zn
₂ SiO ₄ : green light emitting phosphor such as Mn, BaMgAl
A blue light emitting phosphor such as ₁₀ O ₁₇ : Eu is used alone or in combination depending on the desired emission color. (Refer to the December 1997 issue of Electronic Materials Magazine Industrial Research Companies). Among these practical phosphors for VUV which are practically used as the fluorescent film of the VUV-excited light emitting device, the phosphor mainly practically used as the blue component is BaMgAl ₁₀
It is an aluminate phosphor having a composition of O ₁₇ : Eu, which is commonly referred to as BAM. The BAM phosphor has high emission brightness when excited by irradiation with VUV and has a color as blue. Although the purity is good, the luminance deterioration (baking deterioration) in the baking process during the production of the fluorescent film of the VUV-excited light-emitting device is large, and when the VUV-excited light-emitting device is driven, it is exposed to VUV for a long time. It has a drawback that the deterioration of luminance with time (VUV deterioration) is large.

On the other hand, as a blue phosphor with little baking deterioration in the manufacturing process and less VUV deterioration, Eu is used as an activator and its composition formula is CaMgS.
A divalent metal silicate phosphor represented by i ₂ O ₆ : Eu has been reported (Proceedings of The).
8th International Display
y Worksshops 2001 pp. 1115
However, this phosphor is BAM which is a conventional blue phosphor.
The problem is that the brightness is lower than that of (BaMgAl ₁₀ O ₁₇ : Eu).

[0007]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above situation, and is a divalent metal silicate phosphor and a fluorescent material which have less VUV deterioration and have improved emission brightness as compared with conventional ones. An object of the present invention is to provide a body paste composition and a VUV excitation light emitting device.

[0008]

The present inventors have known that VUV deterioration is relatively small, and the composition formula CaMg is known.
Si ₂ O ₆ : EU was added to the host crystal of the divalent metal silicate phosphor, in addition to Eu as an activator, and various metal elements were added, and the emission brightness under VUV excitation was examined. As a result of detailed examination of the effect of the additional element on the composition of the divalent metal silicate whose composition formula is CaMgSi ₂ O ₆ : Eu,
When a specific amount of a is added and it is included in the composition, V
The inventors have found that the emission brightness under UV excitation is enhanced, and when a phosphor film is formed from a phosphor paste composition using this phosphor, a VUV-excited light-emitting device with improved blue component brightness is obtained, and the present invention has been completed. . The above object of the present invention can be achieved by the following configurations.

(1) In a divalent metal silicate phosphor activated by europium (Eu) using a silicate containing calcium (Ca), magnesium (Mg) and silicon (Si) as constituent metal elements as a base crystal. A divalent metal silicate phosphor characterized by containing lanthanum (La) in the composition of the phosphor (the invention of claim 1). (2) The silicate phosphor has a general formula (Ca _1-x Eu)
divalent metal silicate phosphor according to the above (1), characterized by being represented by _{x) O · aMgO · bSiO 2} · cLa 2 O 3 ( the invention of claim 2). (However, in the above formula, a, b, c and x are 0.9 ≦ a ≦ 1.1, 1.9 ≦ b ≦ 2.2 and 0 <c ≦, respectively.
It represents a number satisfying the conditions of 2.5 × 10 ⁻² and 5 × 10 ⁻³ ≦ x ≦ 0.1. )

(3) The above a, b and c are respectively a
= 1, b = 2 and 2.5 × 10 ⁻⁴ ≦ c ≦ 1.5 × 1
The divalent metal silicate phosphor according to (2) above, which is a number satisfying the condition of 0 ⁻² (invention of claim 3). (4) In a phosphor paste composition obtained by dispersing a phosphor in a solvent in which a binder is dissolved, the phosphor is the divalent metal phosphor according to any one of (1) to (3) above. A phosphor paste composition characterized by the above (claim 4). (5) In an ultraviolet-excited light-emitting element that excites the fluorescent film by vacuum ultraviolet light emitted by discharge of a rare gas enclosed in an envelope in which the fluorescent film is formed to emit light, the fluorescent film is A VUV-excited light-emitting device (invention of claim 5), which is formed of the divalent metal silicate phosphor according to any one of (1) to (3).

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
In order to manufacture the phosphor of the present invention, Ca, which constitutes the phosphor, like the conventionally known divalent metal silicate phosphor,
An oxide of each metal of Mg, Si, La, and Eu or a phosphor raw material mixture containing a compound of each metal such as carbonate, sulfate, and halide which can be converted into an oxide at high temperature is stoichiometrically The composition formula is (Ca _1-x Eu _x ) O · aM
gO · bSiO ₂ · cLa ₂ O ₃ (however, in the above formula, x
Is a condition of 5 × 10 ⁻³ ≦ x ≦ 0.1, a, b and c
Are 0.9 ≦ a ≦ 1.1, 1.9 ≦ b ≦ 2.2, and
And a number satisfying the condition of 0 <c ≦ 2.5 × 10 ⁻² . The same applies hereinafter), and mixed in a proportion such that the heat-resistant container such as an alumina crucible is filled with a reducing atmosphere,
It can be produced by baking at least once at a temperature of 1000 to 1400 ° C. for 2 to 40 hours, and subjecting the baked product to post-treatments that are usually performed at the time of manufacturing a phosphor such as dispersion, washing with water, drying and sieving. I can. A flux such as a fluoride may be further added to the phosphor raw material mixture before firing.

FIG. 1 shows a, b and x in the above composition formula.
Values of 1.0, 2.0 and 2 × 10 ⁻² , respectively, and the amount of La added (c value) is different from that of the divalent metal silicate phosphor {(Ca _0.98 Eu _0.02 ). O ・ MgO ・ 2S
iO ₂ · cLa ₂ O ₃ } is produced, and the obtained phosphor is 1
It is the graph which showed the emission brightness of each fluorescent substance when irradiating VUV of 46 nm and making it light-emit with the relative value with respect to the fluorescent substance which La was not added (when c value = 0). Since the brightness of the blue phosphor changes greatly in proportion to the emission color (y value of the chromaticity point in the CIE color system chromaticity coordinates),
As a simple method for comparing the luminous efficiencies of phosphors having different y-values of the luminescent color, it is common to compare the luminescent brightness by the (luminance / y) value (stimulation sum) divided by the y-value. Therefore, also in the present invention, the luminous efficiency (luminance) between the phosphors is compared with each other by the sum of stimulation. In the present specification, the term “luminance of luminance” or “luminance” means “stimulation sum” as defined above. The “relative luminance” on the vertical axis in FIG. 1 is also a relative value of the sum of stimulations obtained for each phosphor.

As can be seen from FIG. 1, a conventional divalent metal silicate phosphor {(Ca _0.98 Eu _0.02 ) O.MgO
The emission brightness is improved by adding a small amount of La to 2SiO ₂ }. However, when the amount of La added is increased above a certain amount, the emission brightness is gradually increased as compared with the phosphor to which La is not added. It can be seen that it will decrease. In addition,
Although not shown, in this silicate phosphor, the ratio (a value) of MgO in the composition was 1.0, and
The ratio of ₂ (b value) is 2.0, and the concentration of Eu (x value)
In the case of a phosphor having a composition other than that having a composition of 2 × 10 ⁻² , when the composition range is such that a predetermined emission brightness can be obtained, the La content (c value) and the VUV excitation of this phosphor are It was confirmed that there is a correlation similar to that of FIG.

Therefore, in the divalent metal silicate of the present invention, when the La content (c value) in the phosphor composition in the above composition formula satisfies the condition of 0 <c ≦ 2.5 × 10 ⁻² , VU
The emission luminance under V excitation is higher than that of a conventional divalent metal silicate phosphor that does not contain La in its composition, and the c value is about 2.5 × 10 ⁻⁴ to 1. 5 x 1
0 and more preferably in the range of ^-2. On the other hand, when the c value is larger than 2.5 × 10 ⁻² , the effect of decreasing the brightness due to the generation of a different phase becomes larger than the effect of increasing the brightness due to the addition of La, which is not preferable.

The values a and b are 0.9 ≦ a ≦ 1.
1 and preferably in the range of 1.9 ≦ b ≦ 2.2,
From the viewpoint of crystallinity of the phosphor, it is particularly preferable that a = 1 and b = 2. If the deviations of the a value and the b value from the above ranges are large, a phosphor having imperfect crystallinity or a different phase is produced as a by-product, which causes a decrease in emission luminance, which is not preferable.

Also, the composition of the Eu concentration (x value) is preferably in the range of 5 × 10 ⁻³ ≦ x ≦ 0.1 in terms of emission brightness, and particularly 5 × 10 ⁻³ ≦ x ≦ 5 × 10. The range of ⁻² is more preferable. When this x value exceeds 0.1, a different phase from the above composition is formed to reduce the brightness of the phosphor, and when it is lower than 5 × 10 ⁻³ , the amount of emission centers is insufficient and the phosphor is obtained. The emission brightness of will be low.

The phosphor paste composition of the present invention is suitable for use by adding the divalent metal silicate phosphor of the present invention to a solvent in which a binder resin is dissolved and thoroughly kneading the mixture to adjust the amount of the solvent. Accordingly, it can be produced by forming a paste having an appropriate viscosity.

As the binder resin for producing the phosphor paste composition of the present invention, ethyl cellulose, nitrocellulose, polyethylene oxide, acrylic resin, etc. are used, and as a solvent used for adjusting the viscosity of the paste. A solvent such as water, butyl acetate, butyl carbitol, or terpineol is used. Further, as the phosphor in the phosphor paste composition of the present invention, a mixed phosphor of the divalent metal silicate phosphor of the present invention and a phosphor having a composition other than this may be used depending on its purpose and application. Not to mention good things.

Further, the VUV-excited light-emitting device of the present invention is coated with the phosphor paste composition of the present invention at a predetermined place in an envelope made of glass or the like, dried and then baked. The VUV-excited light-emitting device is manufactured in the same manner as the conventional VUV-excited light-emitting device, except that the phosphor film made of the divalent metal silicate phosphor of the present invention is formed by forming the phosphor film.

The divalent metal silicate phosphor of the present invention obtained as described above has a higher emission luminance than the conventional divalent metal silicate phosphor containing no La in the composition, The emission brightness of the VUV-excited light-emitting device of the present invention having a phosphor film formed of the phosphor paste composition of the present invention containing this phosphor is increased.

[0021]

[Example 1]

CaCO ₃ 0.98 mol MgCO ₃ 1.0 mol Eu ₂ O ₃ 0.01 mol SiO ₂ 2.0 mol La ₂ O ₃ 0.0005 mol NH ₄ F · HF 0.05 mol

The above compounds were sufficiently mixed to prepare a phosphor raw material, which was filled in an alumina crucible and heated in a reducing atmosphere at a maximum temperature of 1150 ° C. including a temperature raising / lowering time.
Bake over time. The calcined product was subjected to a dispersion, washing with water, drying and sieving treatment which is usually performed as a post-treatment method for the phosphor, and the composition formula was (Ca _0.98 Eu _0.02 ) O.
· _MgO · 2SiO is ₂ · 0.0005La 2 O _3, to obtain a Eu-activated silicate phosphor containing La elements of Example 1.

The thus obtained phosphor powder of Example 1 was filled into a cell having a cylindrical recess having a diameter of 12 mm and a depth of 1 mm, which was pressed with a glass plate to flatten it. Fluorescent surface of different powder is created, and 146 nm is applied to this fluorescent surface.
VUV of the composition was irradiated to excite it to emit light, and the emission brightness and emission color at that time were measured, and the stimulus sum (emission brightness / y value) was measured.
The value was 104% of the stimulated sum of the phosphor of the following Comparative Example 1 represented by _0.98 Eu _0.02 ) O.MgO.2SiO ₂ .

Example 2 CaCO ₃ 0.98 mol MgCO ₃ 1.0 mol Eu ₂ O ₃ 0.01 mol SiO ₂ 2.0 mol La ₂ O ₃ 0.005 mol NH ₄ F · HF 0.05 Mole

The composition formula (C) was obtained in the same manner as the phosphor of Example 1 except that the above compounds were sufficiently mixed to prepare a phosphor raw material.
a _0.98 Eu _0.02 ) O · MgO · 2SiO ₂ ·
The Eu-activated silicate phosphor of Example 2 containing La element, which is 0.005 La ₂ O ₃ , was obtained. In the same manner as in Example 1, the phosphor of Example 2 was excited by vacuum ultraviolet rays of 146 nm to emit light, and the emission brightness and the chromaticity point of the emission color were measured, and the sum of the stimulations (emission brightness / y The value) was determined to be 104% of the stimulated sum of the phosphor of Comparative Example 1 below.

Example 3 CaCO ₃ 0.98 mol MgCO ₃ 1.0 mol Eu ₂ O ₃ 0.01 mol SiO ₂ 2.0 mol La ₂ O ₃ 0.025 mol NH ₄ F · HF 0.05 Mole

The composition formula (C) is the same as that of the phosphor of Example 1 except that the above compounds are sufficiently mixed to prepare a phosphor raw material.
a _0.98 Eu _0.02 ) O · MgO · 2SiO ₂ ·
The Eu-activated silicate phosphor of Example 3 containing La element, which is 0.025 La ₂ O ₃ , was obtained.

In the same manner as in Example 1, the phosphor of Example 3 was excited by vacuum ultraviolet rays of 146 nm to emit light, and the emission luminance and the chromaticity point of the emission color were measured.
When the sum of stimuli (luminance / y value) was determined, it was 94% of the sum of stimuli of the phosphor of Comparative Example 1 below.

Comparative Example 1 CaCO ₃ 0.98 mol MgCO ₃ 1.0 mol Eu ₂ O ₃ 0.01 mol SiO ₂ 2.0 mol NH ₄ F · HF 0.05 mol

The composition formula (C) was obtained in the same manner as the phosphor of Example 1 except that the above compounds were sufficiently mixed to prepare a phosphor raw material.
The Eu-activated silicate phosphor of Comparative Example 1 having a _0.98 Eu _0.02 ) O.MgO.2SiO ₂ was obtained.

In the same manner as in Example 1, the phosphor of Comparative Example 1 was excited by vacuum ultraviolet rays of 146 nm to emit light, and the emission brightness and the chromaticity point of the emission color were measured. The sum (emission brightness / y value) was determined and used as the reference value for the emission brightness of the phosphors of the above-mentioned examples.

[0032]

[Brief description of drawings]

FIG. 1 shows the La in the divalent metal silicate phosphor of the present invention.
It is a graph which illustrates the correlation of content (c) and the stimulus sum (luminance / y) of luminescence of fluorescent substance.

[0033]

EFFECTS OF THE INVENTION The present invention can provide a divalent metal silicate phosphor and a phosphor paste composition having a higher emission brightness than conventional ones, especially under VUV excitation, by adopting the above constitution. By applying this to the fluorescent film of the VUV-excited light-emitting device, it is possible to provide a VUV-excited light-emitting device with improved blue component emission efficiency.

Claims (5)

[Claims] 1. Calcium (Ca), magnesium (M
g) and silicate containing silicon (Si) as a constituent metal element as a base crystal and activated with europium (Eu) 2
A divalent metal silicate phosphor, wherein lanthanum (La) is contained in the composition of the valent metal silicate phosphor. 2. The phosphor of the general formula (Ca _1-x Eu)
silicate phosphor according to claim 1, characterized by being represented by _{x) O · aMgO · bSiO 2} · cLa 2 O 3.
(However, in the above formula, a, b, c and x are 0.9 ≦ a ≦ 1.1, 1.9 ≦ b ≦ 2.2 and 0 <c ≦, respectively.
It represents a number satisfying the conditions of 2.5 × 10 ⁻² and 5 × 10 ⁻³ ≦ x ≦ 0.1. ) 3. The above a, b and c are respectively a = 1,
b = 2 and 2.5 × 10 ⁻⁴ ≦ c ≦ 1.5 × 10 ⁻²
The divalent metal silicate phosphor according to claim 2, which is a number satisfying the following condition. 4. A phosphor paste composition obtained by dispersing a phosphor in a solvent in which a binder is dissolved, wherein the phosphor is the divalent metal phosphor according to any one of claims 1 to 3. A phosphor paste composition comprising: 5. An ultraviolet-excited light-emitting device that excites the fluorescent film by vacuum ultraviolet rays emitted by the discharge of a rare gas enclosed in an envelope in which the fluorescent film is formed to emit light. A VUV-excited light-emitting device, which is formed of the divalent metal silicate phosphor according to any one of claims 1 to 3.