JP2003342564A - Bivalent metal silicate fluorescent material, fluorescent paste composition and light-emitting element excited by vacuum ultraviolet ray - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bivalent silicate fluorescent material emitting blue light and resistant to the deterioration with vacuum ultraviolet rays, a fluorescent paste composition and a VUV-excited light-emitting element causing little lowering of luminance with time in excited state and having prolonged life. <P>SOLUTION: The bivalent silicate fluorescent material is produced by using a silicate containing Ca, Mg and Si as constitution metal elements and doping with Eu. The material is further incorporated with at least one element selected from Ba, Sr, Zn, Y, Ce, In and Bi. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a divalent metal silicate phosphor which emits blue light when excited by vacuum ultraviolet rays (VUV) having a wavelength of 200 nm or less and exhibits little deterioration in luminance over time, and fluorescence containing this phosphor. The present invention relates to a body paste composition and a VUV-excited light-emitting device (VUV-excited light-emitting device) that exhibits little deterioration with time during driving.

[0002]

2. Description of the Related Art In recent years, Ar, Xe, He, as represented by rare gas lamps and plasma display panels (PDP) used as light sources for reading in scanners, etc.
A rare gas such as Ne or Xe-Ne is enclosed in an envelope made of glass or the like, and the VUV emitted by the discharge of the rare gas excites the fluorescent film made of the VUV phosphor inside the envelope. A VUV-excited light-emitting device having a structure for emitting light is actively developed.

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, a PDP, which is another typical example of a VUV-excited light-emitting device, has the VUV-excited rare gas lamp further reduced in size, and the rare gas lamps of three different colors are arranged in stripes or in a matrix. It can be thought of as being arranged in. 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 V
A fluorescent film made of a fluorescent substance for UV 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. For full color PDP,
Full-color display can be performed by arranging the cells, each of which has a phosphor film of a phosphor that emits red, blue, and green when excited by VUV, 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 electronic material magazine December 1997 issue, industrial research companies, etc.). 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.
An aluminate phosphor having a composition of ₁₀ O ₁₇ : Eu, which is commonly referred to as BAM, has a high emission brightness when excited by irradiation with VUV, and has a blue color. Although the color purity is good, the luminance deterioration (baking deterioration) in the baking process during the formation of the fluorescent film of the VUV-excited light-emitting element using this phosphor is large, and the VUV-excited light-emitting element is driven to increase the VUV. It has a drawback that the emission luminance decreases (VUV deterioration) over time when exposed to time, and development of a blue-emitting VUV excitation phosphor with less baking deterioration and VUV deterioration is desired. There is.

By the way, one of the blue light emitting phosphors having relatively little deterioration in baking and VUV is Eu, which is an activator and has a composition formula of CaMgSi ₂ O ₆ : Eu. Phosphors have been reported (Proce
edings of the8th Internet
Ional Display Worksshops20
01 pp. 1115). However, in the case of this phosphor, although the degree of baking deterioration and VUV deterioration is relatively small, in particular, VUV deterioration is not always practically sufficient, and further improvement has been desired.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above situation, and has a VUV more than the conventional one.
It is an object of the present invention to provide a blue-emitting divalent silicate phosphor having improved deterioration, a phosphor paste composition, and a VUV-excited light-emitting device having less deterioration in luminance over time during driving and an improved life. .

[0008]

Means for Solving the Problems The present inventors have found that the composition formula C
Various studies have been conducted on a silicate phosphor represented by aMgSi ₂ O ₆ : Eu, which uses Eu as an activator.
VUV deterioration is particularly reduced only when a specific amount of a specific metal element is contained in a matrix of an activated divalent metal silicate phosphor, and a phosphor film is formed by a phosphor paste composition containing this phosphor. The VUV-excited light-emitting device has been found to reduce the deterioration of luminance with time during driving, and has reached the present invention. That is, the above object of the present invention is achieved by adopting the following configuration.

(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. In the composition of the phosphor, at least one of barium (Ba), strontium (Sr), zinc (Zn), yttrium (Y), cerium (Ce), indium (In) and bismuth (Bi) is contained. A divalent metal silicate phosphor characterized by:

(2) The phosphor has the general formula (Ca
^{_{1-x-u Eu x M}} II u) O · a (Mg 1-v Z
n _v ) O · bSiO ₂ · wM ^III . The divalent metal silicate phosphor according to (1) above.
{However, in the above formula, M ^II represents at least one metal element selected from barium (Ba) and strontium (Sr), and M ^III represents yttrium (Y) and cerium (C).
e), at least one metal element selected from indium (In) and bismuth (Bi), and a, b, x, u,
v and w are 0.9 ≦ a ≦ 1.1 and 1.9 ≦ b, respectively.
≦ 2.2, 5 × 10 ⁻³ ≦ x ≦ 10 ⁻¹ and 0 <u + v
It represents a number that satisfies the condition of + w ≦ 4 × 10 ⁻¹ . }

(3) u, v and w are 0 respectively
≦ u ≦ 2 × 10 ⁻¹ , 0 ≦ v ≦ 10 ⁻¹ and 0 ≦ w ≦
The divalent metal silicate phosphor according to (2) above, which is a number satisfying the condition of 10 ⁻¹ . (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 silicate phosphor according to any one of (1) to (3) above. A phosphor paste composition characterized by being.

(5) In the ultraviolet-excited light-emitting device that excites the fluorescent film by vacuum ultraviolet rays emitted by the discharge of the rare gas enclosed in the envelope in which the fluorescent film is formed to emit light, Is formed by the phosphor according to any one of the above (1) to (3), and a VUV-excited light-emitting device is characterized.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
To manufacture the phosphor of the present invention, stoichiometrically (Ca
^{_{1-x-u Eu x M}} II u) O · a (Mg 1-v Z
n _v ) O · bSiO ₂ · wM ^III (however, in the above formula,
M ^II represents at least one metal element among Ba and Sr, M ^III represents at least one metal element among Y, Ce, In and Bi, and a, b, w, x, u
And v are 0.9 ≦ a ≦ 1.1 and 1.9 ≦ b ≦, respectively.
2.2, 5 × 10 ⁻³ ≦ x ≦ 10 ⁻¹ and 0 <u + v +
It represents a number satisfying the condition of w ≦ 4 × 10 ⁻¹ . The same applies hereinafter. }, Ca and M that constitute the phosphor at a ratio of
g, Si, Eu, Zn, an oxide of each metal element of M ^II and M ^III , or a compound of each metal such as a carbonate, a sulfate or a halide which can be converted into an oxide of the above metal at high temperature The phosphor raw material mixture was filled in a heat-resistant container such as an alumina crucible, and the mixture was heated to 1000 to 1400 in a reducing atmosphere.
It can be produced by calcining at least once at a temperature of ° C for 2 to 40 hours, and subjecting the calcined product to post-treatments of dispersion, washing with water, drying and sieving. A flux such as a fluoride may be further added to the phosphor raw material mixture before firing.

Thus, the general formula is (Ca _1-x-u
Eu _x M ^II _u ) O · a (Mg _1-v Zn _v ) O · bS
The Eu-activated divalent metal silicate phosphor represented by iO ₂ · wM ^III of the present invention is obtained. In the phosphor of the present invention, when the M ^III metal element is Ce, Ce is C
It is considered that it exists in the phosphor matrix in the form of eO ₂ or Ce ₂ O ₃ , and when the M ^III metal element is In, it is In
Is in the form of In ₂ O or In ₂ O ₃ , and also M ^III
When the metal element is Bi, Bi is BiO, Bi ₂ O ₃ ,
Bi ₂ O ₄ , Bi ₂ O ₅ , Bi ₄ O _{7 and the} like, which are each considered to be present in the phosphor matrix, for example, M ^II
It is possible that the element or the Eu element does not completely replace the lattice point of the Ca element, or the Zn element does not completely replace the lattice point of the Mg element in the crystal.
In the present invention, the general formula including the phosphor having such a crystal composition is (Ca _1-x-u Eu _x M ^II _u ) Oa (Mg).
_The phosphor represented by _1-v Zn _v ) O.bSiO ₂ .wM ^III is Ca, Mg, Si, M ^II contained in the phosphor produced by firing the phosphor raw material mixture. M
A phosphor in which the composition ratio of each metal element of ^III and Eu satisfies the composition ratio (molar ratio) represented by the above general formula.

The Eu-activated divalent metal silicate phosphor of the present invention is a metal element M ^II , Zn and a metal element M.
By containing ^III , VUV deterioration of the conventional Eu-activated divalent metal silicate phosphor not containing these is improved, but M ^II and Z for suppressing VUV deterioration are improved.
The total amount of n and M ^III (u + v + w) is 4 ×
When it is more than 10 ^-1 , it is not preferable because the emission luminance is lower than that of the phosphor containing no M ^II , Zn and M ^III . Therefore, in order to obtain a phosphor that suppresses VUV deterioration and maintains a practical brightness, M ^II , Zn and M
The total content (u + v + w) of the metal elements of ^III is 0.
It is more preferable that it is in the range of 4 × 10 ⁻¹ or less. ^{Incidentally, M} II, of Zn and ^{M III,} large ^{effect towards} Zn, and ^{M III reduces} emission luminance compared with ^{M II,} considering the extent of light emission luminance drop ^{M II,}
The respective contents (u, v and w) of Zn and M ^III are 0 ≦ u ≦ 2 × 10 ⁻¹ and 0 ≦ v ≦ 10, respectively.
⁻¹ and 0 ≦ w ≦ 10 ⁻¹ (where u + v + w ≠ 0)
It is more preferable to set the range to.

The divalent metal silicate phosphor of the present invention is
The a value and the b value representing the composition of the host crystal are 1.
As it deviates from 0 and 2.0, the probability that an incompletely crystalline phosphor or a different phase is formed and the emission brightness gradually decreases. Therefore, in view of the emission brightness of the obtained phosphor,
Value and b value are 0.9 ≦ a ≦ 1.1 and 1.9 ≦, respectively.
It is preferably a number that satisfies the range of b ≦ 2.2, and it is particularly preferable that the a value and the b value are a = 1.0 and b = 2.0, respectively. Further, when the above x value representing the activation amount of Eu exceeds 0.1, a different phase from the above composition is formed to reduce the brightness of the phosphor, and the x value is 5 × 10 ^−3.
If it is smaller than this, the amount of luminescent centers becomes insufficient and the emission intensity of the obtained phosphor becomes low, which is not preferable. Therefore, the activation amount (x value) of Eu is preferably a number satisfying the range of 5 × 10 ⁻³ ≦ x ≦ 1 × 10 ⁻¹ in terms of the emission brightness of the obtained phosphor.

The phosphor paste composition of the present invention is prepared by adding the above divalent metal silicate phosphor of the present invention to a solvent in which a binder resin is dissolved and thoroughly kneading to adjust the amount of the solvent. It can be produced by forming a paste having an appropriate viscosity according to its application. As a binder resin for producing a phosphor paste composition containing the phosphor of the present invention, ethyl cellulose, nitrocellulose, polyethylene oxide, acrylic resin or the like is used, and is also used for adjusting the viscosity of the paste. As the solvent, water, butyl acetate, butyl carbitol, terpineol or the like 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, in the VUV-excited light-emitting device of the present invention, the phosphor paste composition of the present invention is applied to a predetermined place in an envelope made of glass or the like, dried and then baked to form a phosphor film. As a result, the conventional V film is formed except that the phosphor film made of the divalent metal silicate phosphor of the present invention is formed.
It is manufactured in the same manner as the UV excitation light emitting device.

The divalent metal silicate phosphor of the present invention thus obtained is a conventional divalent metal silicate phosphor which does not contain any of the metal elements M ^II and M ^{III in} the composition. Compared with this, VUV deterioration is less, and 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 shows less decrease in luminance with time during device operation.

[0020]

[Example 1]

CaCO ₃ 0.97 mol MgCO ₃ 1.0 mol BaCO ₃ 0.01 mol SiO ₂ 2.0 mol Eu ₂ O ₃ 0.01 mol NH ₄ F · HF 0.05 mol

After the above phosphor raw materials are sufficiently mixed, they are filled in an alumina crucible and the maximum temperature is 115 in a reducing atmosphere.
Firing was carried out at 0 ° C. for 14 hours including the temperature rising / falling time. The calcined product is lightly crushed, dispersed, washed with water, dried, and passed through a sieve again to have a uniform particle size.
_0.97 Eu _0.02 Ba _0.01 ) O.MgO.2S
An Eu-activated divalent metal silicate phosphor of Example 1, which is iO ₂ , was obtained.

Next, 30% by weight of the obtained phosphor and 70% by weight of a mixture of a binder resin and a solvent were kneaded to produce a phosphor paste composition of Example 1, and this paste composition was used as a glass composition. Instead of applying to the inner wall of the thin tube, the paste composition is separately applied to a glass plate, dried, and subjected to baking treatment to form a fluorescent film on the glass plate, which is inserted into the glass thin tube to insert the thin film. After the both ends were sealed and the tube was once evacuated, a mixed gas of Ne (95%) + Xe (5%) was sealed and electrodes were provided at both ends of the tube to manufacture the rare gas lamp of Example 1.

Next, when the electrode of the rare gas lamp of Example 1 was energized and continuously lit for 96 hours to cause the fluorescent film in the lamp to emit light, the stimulation sum maintenance rate (M ₉₆ ) at that time was obtained.
Was 103.2%, which was higher than the conventional Eu-activated divalent metal silicate phosphor of the following Comparative Example which did not contain Ba, and had a higher stimulation sum maintenance ratio, and was higher than the luminance immediately after lighting.

The brightness of the blue phosphor depends on its emission color (C
The y-value changes greatly in proportion to the y value of the chromaticity coordinate according to the IE color system. Therefore, as a simple method for comparing the light-emission efficiencies between the blue-emitting phosphors having different y-values of the light-emission color, Generally, comparison is performed by (luminance / y) value (hereinafter referred to as “stimulation sum”) obtained by dividing luminance by y value when represented by coordinates (x, y). Therefore, the rare gas lamp of Example 1 is continuously lit, and the value of the sum of stimulations (I ₉₆ ) defined above and the value of the sum of stimulations immediately after lighting (I ₀ ) after 96 hours
Respectively, and the relative percentage of the value of the sum of stimuli after 96 hours [(I
₉₆ ) / (I ₀ )] × 100 (%)] was calculated and this value was used as the above stimulation sum maintenance rate (M ₉₆ ).

Examples 2 to 9 Example 2 was carried out in the same manner as the phosphor of Example 1 except that each phosphor raw material shown in Table 1 and the compound having the compounding ratio (in mol) were used as the phosphor raw material. ˜9 Eu-activated divalent metal silicate phosphors were obtained.

Next, Examples 2 to 9 were carried out in the same manner as the phosphor paste composition of Example 1 except that the phosphors of Examples 2 to 9 were used as the phosphors instead of the phosphors of Example 1.
The phosphor paste composition of Example 1 was manufactured, and the rare gas lamps of Examples 2 to 9 were manufactured in the same manner as the rare gas lamp of Example 1 using this paste composition.

Next, the stimulation sum maintenance rate (M ₉₆ ) after the rare gas lamps of Examples 2 to 9 were lit for 96 hours was measured in the same manner as in Example 1 and used for the fluorescent film of the rare gas lamps. Table 2 shows the composition of the phosphors. The stimulation sum maintenance rates of the phosphors of Examples 2 to 9 are
The brightness was higher than that of the conventional Eu-activated divalent metal silicate phosphor of the comparative example below, and the brightness after 96 hours of lighting was higher than the brightness immediately after lighting.

Comparative Example CaCO ₃ 0.98 mol MgCO ₃ 1.0 mol SiO ₂ 2.0 mol Eu ₂ O ₃ 0.01 mol NH ₄ F · HF 0.05 mol Each of the above compounds was used as a phosphor raw material. Example 1 except that it was used
And the composition formula is (Ca _0.98 Eu _0.02 ) O
A Eu activated silicate phosphor of Comparative Example, which is MgO.2SiO ₂ , was obtained.

A phosphor paste composition of the comparative example was produced in the same manner as the phosphor paste composition of the example 1 except that the phosphor of the comparative example was used in place of the phosphor of the example 1. Using this paste composition, a rare gas lamp of Comparative Example 1 was manufactured in the same manner as the rare gas lamp of Example 1. Then, the stimulation sum maintenance rate (M ₉₆ ) after the rare gas lamp of Comparative Example was lit for 96 hours was measured in the same manner as in Example 1, and it was 99.8%.

[0030]

[Table 1]

[0031]

[Table 2]

[0032]

EFFECTS OF THE INVENTION The present invention, by adopting the above-mentioned constitution, is more resistant to V than the conventional Eu-activated divalent metal silicate phosphor.
It is possible to provide a phosphor and a phosphor paste having improved UV property and less VUV deterioration. By using this phosphor as a phosphor film, there is little deterioration in luminance over time during driving of a VUV-excited light emitting device, and the life is improved. It has become possible to provide a VUV excitation light emitting device.

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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
In a valent metal silicate phosphor, barium (Ba), strontium (Sr), zinc (Z
n), yttrium (Y), cerium (Ce), indium (In) and bismuth (Bi), at least one kind of divalent metal silicate phosphor characterized by the above-mentioned. 2. The phosphor of the general formula (Ca _1-x-u
Eu _x M ^II _u ) O · a (Mg _1-v Zn _v ) O · bS
The divalent metal silicate phosphor according to claim 1, which is represented by iO ₂ · wM ^III . {However, in the above formula,
M ^II is barium (Ba) and strontium (S
It represents at least one kind of metal element in the ^{r), M III}
Represents at least one metal element among yttrium (Y), cerium (Ce), indium (In) and bismuth (Bi), and a, b, x, u, v and w are each 0.9 ≦ a. ≦ 1.1, 1.9 ≦ b ≦ 2.2, 5 × 1
0 ⁻³ ≦ x ≦ 10 ⁻¹ and 0 <u + v + w ≦ 4 × 10
Represents a number that satisfies the condition ^-1 . } 3. The above u, v and w are each 0 ≦ u ≦
2 × 10 ⁻¹ , 0 ≦ v ≦ 10 ⁻¹ and 0 ≦ w ≦ 10
3. The divalent metal silicate phosphor according to claim 2, which is a number satisfying the condition ^-1 . 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 silicate phosphor according to any one of claims 1 to 3. A phosphor paste composition characterized by being. 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 comprising the phosphor according to any one of claims 1 to 3.