JP2001214162A - Phosphor comprising oxynitride glass as matrix material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a phosphor suitable for a visible illuminant, including a white LED phosphor which uses blue LED as an illuminant, and conventionally, an oxide series phosphor has generally over 400 nm and greatly decreases excitation spectrum intensity, and in white LED coated an InGaN series blue LED(light emission diode) ship with a YAG series fluophor, an excitation peak of the fluophor does not effectively lap on a light emission peak of the blue LED and locates in a short wavelength side, resultingly, in a white LED manufacture with high luminance, the phosphor has not good excitation efficiency. SOLUTION: The phosphor comprising an oxynitride glass matrix comprises CaCO3 of 20-50 mol% (in terms of CaO), Al2O3 of 0-30 mol%, SiO of 25-60 mol%, AlN of 5-50 mol%, and a rare earth oxide or a transition metallic oxide of 0.1-20 mol% (the sum of the five components is 100 mol%). A content of nitrogen is <=15%. Another rare earth element ion of 0.1-10 mol% (in terms of an oxide) may be contained on fluorescent glass as a coactivating agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phosphor, particularly a phosphor useful as a phosphor of a white light emitting diode (white LED) using a blue light emitting diode (blue LED) as a light source.

[0002]

2. Description of the Related Art Oxide light emitters in the form of powders and thin films using rare earth elements have been widely known, but on the other hand, there have been few studies on light emitters in which a non-oxide is activated with a rare earth element. For nitrides and oxynitrides, Si-ON-based oxynitride crystals having a β-sialon structure or the like (JP-A-60-206889, JWHvan Krevel)
etal `` Long wavelength Ce ³⁺ emission in Y-Si-0-Nma
terials '', Journal of Alloys and Compounds 268 (199
8) 272-277) are merely disclosed.

[0003] Further, as a luminous body in a glassy state, not a crystalline powder or a thin film, Eu ₂ O ₃ which is a luminescent center is used.
Fluorescent glass (Japanese Patent Application Laid-Open No. 8-133780) and oxide fluorescent glass (Japanese Patent Application Laid-Open No. H10-167755) containing a relatively large amount of Tb ₂ O ₃ or Tb ₂ O ₃ are known.

Conventionally, fields requiring reliability such as disaster prevention lighting in the lighting equipment industry and display industry, fields where small size and light weight are preferred such as in-vehicle lighting and liquid crystal backlight, and visibility guides such as destination guide boards at stations are required. White LE in the field
D is used. The emission color of the white LED is obtained based on the principle of light color mixing, and the blue light absorbed by the phosphor also functions as an excitation source and emits yellow fluorescence. The yellow light and the blue light are mixed and appear to human eyes as white.

[0005] As a phosphor suitable for a white LED,
(Y, Gd)_Three(Al, Ga)_FiveO ₁₂Represented by the composition formula
Phosphor doped with Ce in YAG-based oxide matrix
It has been known. This phosphor has been conventionally used as a light-emitting source InG.
For thin coating on the aN blue LED chip surface
It has been.

However, the emission peak of an lnGaN blue LED used as a light source for a white LED shows 465 to 465.
At 520 nm, it is located on the longer wavelength side than the wavelength range in which the YAG-based phosphor can be excited.

[0007]

Generally, conventional oxide-based phosphors have a remarkable decrease in excitation spectrum intensity when the wavelength exceeds 400 nm. Therefore, InGa
In a white LED (white light emitting diode) made by applying a YAG-based phosphor to an N-based blue LED chip, the excitation peak of the phosphor does not efficiently overlap the emission peak of the blue LED and is located on the shorter wavelength side. Therefore, the high brightness white L
It was not necessarily a phosphor with high excitation efficiency for producing ED.

[0008]

Means for Solving the Problems Accordingly, the present inventor has proposed an acid
Part of element (2) is replaced with nitrogen (3)
If the ratio of ionicity or covalentness changes, the excitation / emission wavelength
The idea was that it would change freely, and the overall charge was neutralized.
Alkaline earth (+ divalent) in lanced glass system
And the emission center ion were added to complete the present invention. like this
The new idea is a new one, with a wide wavelength range of visible and ultraviolet light.
Oxynitride with an excitation spectrum around (≤550 nm)
There is no example of producing a fluoride glass. That is, the fluorescence of the present invention
The body uses oxynitride glass as the base material,
Material Ca²⁺Eu that makes a part of ions a luminescence center²⁺, E
u³⁺, Ce³⁺, Tb ³⁺Rare earth ion such as C or C
r³⁺, Mn²⁺Synthesized by replacing with transition metal ions such as
Things.

According to the present invention, CaCO ₃ is converted to C
in terms of aO-: 20 to 50 mol%, Al ₂ O _3: 0~
30 mol%, SiO: 25-60 mol%, AlN: 5-
50 mol%, rare earth oxide or transition metal oxide: 0.
It is a phosphor whose base material is oxynitride glass in which the total of the five components is 1 to 20 mol% and the total of the five components is 100 mol%.

Further, according to the present invention, the nitrogen content is 15 wt%.
A phosphor using the above oxynitride glass as a base material, characterized in that:

Further, the present invention provides a fluorescent glass having a rare earth oxide ion as a rare earth oxide in addition to the rare earth oxide ion in a content of 0.1 to 10 mol% in the fluorescent glass. A phosphor using the above oxynitride glass as a base material, characterized in that the phosphor is contained as a co-activator.

Further, the present invention provides an InGaN-based blue LE
It is a white LED using the above-mentioned phosphor using D as a light source.

The CaCO ₃ component of the phosphor of the present invention is C
It is a raw material of aO and not only expands vitrification range,
A large amount of rare earth ions or transition metal ions serving as luminescent centers can be stably contained in the fluorescent glass. The range of 20 to 30 mol% is more preferable. In addition,
As described above, the content of the rare earth oxide or transition metal oxide serving as the luminescence center ion by easily replacing the Ca ²⁺ ion at the Ca ²⁺ site with Sr ²⁺ or Ba ²⁺ ion is as described above. It is possible to control freely within the range of mol%.

AlN and Al ₂ O ₃ are used to change the nitrogen content. AlN 40 to 10 mol%, Al
More preferably, ₂ O ₃ is in the range of 0 to 20 mol%. SiO
₂ is one of the glass forming components, and CaO In combination, the melting temperature of the glass melt is lowered.
A range of 30 to 40 mol% is more preferable.

The rare earth oxide or transition metal oxide is E
Raw material for doping rare earth ions such as u ²⁺ , Eu ³⁺ , Ce ³⁺ , Tb ³⁺ or transition metal ions such as Cr ³⁺ , Mn ²⁺ into glass. The glass composition limit of 20 mol%
It is activated in the following range, and has a strong luminescence intensity at an activation amount of 0.5 to 10 mol% where no concentration quenching of the luminescence center is observed.

The oxynitride glass is obtained by substituting a part of oxygen with nitrogen. By introducing nitrogen, the chemical bond of the glass network structure is strengthened, and in addition to thermal properties such as glass transition temperature and softening temperature, Mechanical properties and chemical properties are significantly improved (for example, Japanese Patent Publication No. 7-33733).
It is known.

In the phosphor of the present invention, the nitrogen content in the glass can be controlled to shift the peak position of the emission spectrum in the glass composition range of 15 wt% or less. The peak wavelength in the excitation spectrum of the phosphor can be adjusted in a range from ultraviolet to green. Since the shift of the emission peak wavelength gradually changes from yellow to red, by changing the nitrogen content, multicoloring of the phosphor can be easily achieved. A more preferred nitrogen content is 4-7 wt%.

There are two typical methods for producing oxynitride glass. One is a method using a nitride as a nitrogen source and the other is a sol-gel method. There is a method of nitriding the produced porous glass with ammonia gas.

In the former method, the nitride is decomposed at a high temperature during melting, so that it is very difficult to increase the nitrogen content to 10% by weight or more. For example, these glasses are synthesized under a nitrogen pressure of 10 atm. As a result, an oxynitride glass containing a relatively large amount of nitrogen can be obtained. Such oxynitride glasses are more excellent in mechanical strength and chemical stability

The fluorescent glass basically contains only one kind of emission center. However, it is possible that two kinds of rare earth elements are contained in the fluorescent glass. The two effects of doping the fluorescent glass at the same time can be cited as two effects. One is a sensitizing effect, and the other is to newly form a trap level of a carrier and to develop and improve long afterglow and to improve thermoluminescence. In general, combinations in which a sensitizing effect is observed include Tb ³⁺ ions for Eu ³⁺ ions and Ce ³⁺ ions for Tb ³⁺ ions.

In order to use other rare earth element ions (such as Gd ³⁺ , Tb ³⁺ , Dy ³⁺ , or Sm ³⁺ ) as sensitizers in addition to Eu ²⁺ (or Ce ³⁺ ) ions, These rare earth oxides can be contained as a coactivator in the fluorescent glass at a content of 0.1 to 10 mol%.

As the oxynitride glass, Si—O—
N, Mg-Si-ON, Al-Si-ON, Nd-
Al-Si-ON, Y-Al-Si-ON, Ca-
Al-Si-ON, Mg-Al-Si-ON, Na
--- Si-ON, Na-Ca-Si-ON, Li-
Ca-Al-Si-ON, Na-B-Si-ON,
Na-Ba-B-Al-Si-ON, Ba-Al-S
i-ON, Na-B-ON, Li-PON, N
Systems such as a-P-O-N are known

Among these systems, the base material of the present invention is a Ca-Al-Si-ON-based oxynitride glass (manufactured by Sakuhana et al. In 1983. "Journal of No.
n-Crystalline Solids 56 (1983) 147-152).

It is reported that the Ca-Al-Si-ON-based oxynitride glass has a nitrogen content of about 5.5 wt%, and this oxynitride glass is used as a base glass for the phosphor of the present invention. Can be used.

The method of producing the Ca-Al-Si-ON-based oxynitride glass phosphor of the present invention can use the above-mentioned conventionally known method. In this case, a rare earth oxide is used as a raw material. The raw material is mixed with other raw materials, and heated and melted in a nitrogen atmosphere as a starting raw material to synthesize fluorescent glass.

For example, rare earth oxides and metal oxides CaO
(← CaCO ₃ , Al ₂ O ₃ , SiO ₂ ) can be synthesized by adding AlN and melting at a high temperature, for example, about 1700 ° C. At this time, the nitrogen content in the glass can be changed by changing the ratio between Al ₂ O ₃ and AlN.

The following is a description of Ca − doped with Eu ²⁺ ions.
The relationship between the nitrogen content and the excitation / fluorescence spectrum of the Al-Si-ON-based oxynitride glass will be described in detail. The sample was prepared using the following raw material composition. The raw material powder was mixed with the following compositions of Samples A, B and C, and the mixed sample powder was wrapped in molybdenum foil in order to avoid a reaction with the furnace material.
For 2 hours, and then rapidly cooled to obtain a fluorescent glass.

(Sample A) CaCO ₃ : Al ₂ O ₃ : SiO ₂ : AlN: Eu ₂ O
₃ = 24.0: 3.3: 33.4: 33.3: 6.0
(N: 5 wt%) (Sample B) CaCO ₃ : Al ₂ O ₃ : SiO ₂ : AlN: Eu ₂ O
₃ = 26.2: 9.1: 36.4: 21.8: 6.5
(N: 3 wt%) (Sample C) CaCO ₃ : Al ₂ O ₃ : SiO ₂ : AlN: Eu ₂ O
₃ = 27.7: 15.4: 38.5: 11.5: 6.9
(N: 2 wt%)

FIG. 1 shows a graph of Ca− doped with Eu ²⁺ ions.
1 shows an excitation / fluorescence spectrum of an Al-Si-ON-based oxynitride glass. The nitrogen content of the fluorescent glass
From sample No. to sample C. The excitation spectrum intensity of these phosphors increases sharply from 400 nm,
It has a maximum value around 500 nm. On the other hand, the peak of the emission spectrum was around 600 nm (red). The position of the emission spectrum shifted to the shorter wavelength side as the nitrogen content in the glass decreased. Thus, by controlling the nitrogen content, it is possible to make the phosphor polychromatic. Sample A has a nitrogen content of about 5 wt% and sample B
Has a nitrogen content of about 3 wt% and sample C contains about 2 w
It has a nitrogen content of t%.

The excitation spectrum of FIG. 1 has two peaks. The peak at 250 to 350 nm is in the charge transfer absorption band of Eu—O, while the peak at 450 to 550 nm is
It is assigned to the u-N charge transfer absorption band. Therefore, if the nitrogen content in the fluorescent glass decreases, 450-
The peak of the charge transfer absorption band of Eu-O at 550 nm decreases.

The oxynitride glass phosphor of the present invention comprises
Excitation light (450-550nm) for nGaN blue LED
In this case, it can be said that the larger the nitrogen content, the better. Comparing Sample A and Sample B, it can be seen that the peak of the Eu-N charge transfer absorption band shifts to the longer wavelength side as the nitrogen content increases. Therefore, by slightly changing the nitrogen content, it is possible to match the wavelength of the excitation light of various blue LEDs.

When the nitrogen content is reduced from sample A to sample C, the emission peak continuously moves from 680 nm to 580 nm. If the peak position of the excitation spectrum is not taken into the material design, a fluorescent glass having emission from 580 to 680 nm can be obtained by controlling the nitrogen content.

From the above results, the nitrogen content is 4 to 7 watts.
t% is good, and by changing the nitrogen content in this range, a fluorescent glass having an excitation / emission spectrum as required can be synthesized.

[0034]

Example 1 Example doped with Eu ²⁺ ions Raw material powder was mixed with the following composition, this mixed sample powder was wrapped in molybdenum foil, and was heated at 1700 ° C. in a nitrogen atmosphere using a high-frequency heating furnace. The mixture was heated and melted for 2 hours, and then rapidly cooled to obtain a fluorescent glass.

(Sample A) CaCO ₃ : Al ₂ O ₃ : SiO ₂ : AlN: Eu ₂ O
₃ = 28.2: 3.1: 31.4: 31.3: 6.0
(N: 5 wt%) (Eu: 12.0%) (Sample B) CaCO ₃ : Al ₂ O ₃ : SiO ₂ : AlN: Eu ₂ O
₃ = 28.6: 3.1: 31.9: 31.8: 4.6
(N: 5 wt%) (Eu: 9.2%) (Sample C) CaCO ₃ : Al ₂ O ₃ : SiO ₂ : AlN: Eu ₂ O
₃ = 29.1: 3.2: 32.3: 32.3: 3.1
(N: 5 wt%) (Eu: 6.2%) (Sample D) CaCO ₃ : Al ₂ O ₃ : SiO ₂ : AlN: Eu ₂ O
_{3 2} = 29.4: 3.2: 32.7: 32.6: 2.1
(N: 5 wt%) (Eu: 4.2%)

FIG. 2 shows excitation / emission spectra of Ca-Al-Si-ON-based oxynitride glasses having different doping amounts of Eu ²⁺ ions. The shape of the excitation / emission spectrum is the same regardless of the doping amount of Eu ²⁺ ions. However, the excitation / emission peak shifts from D to A and moves to the longer wavelength side as the amount of Eu ²⁺ ions in the fluorescent glass increases.

Example 2 Example in which Ce ³⁺ ions were doped Raw material powders were mixed with the following composition, and the mixed sample powder was wrapped in molybdenum foil.
The mixture was heated and melted at 1700 ° C. for 2 hours, and then rapidly cooled to obtain a fluorescent glass.

(Sample A) CaCO ₃ : Al ₂ O ₃ : SiO ₂ : AlN: CeO ₂
= 28.3: 3.3: 33.8: 33.6: 1.0
(N: 5 wt%) (Ce: 1.0%) (Sample B) CaCO ₃ : Al ₂ O ₃ : SiO ₂ : AlN: CeO ₂
= 29.5: 3.3: 33.4: 33.3: 0.5
(N: 5 wt%) (Ce: 0.5%)

FIG. 3 shows that Ca − doped with Ce ³⁺ ions.
1 shows an excitation / emission spectrum of an Al-Si-ON-based oxynitride. Although the shape of the excitation spectrum greatly changed with the change of the doping amount of Ce ³⁺ ions, the emission spectrum did not change much and showed a broad peak having a maximum value in the range of 400 to 450 nm. Ce
The excitation spectrum of Sample B having a small doping amount of ³⁺ ions has two peaks, and the peak at 200 to 330 nm is Ce ³⁺ − O, the peak at 330 to 400 nm is Ce ³⁺
-N is assigned to the charge transfer absorption band. Each of these fluorescent glasses has a long afterglow that continues to emit light even after the irradiation of the ultraviolet light as the excitation light is stopped.

Example 3 Example in which Cr ³⁺ was doped Raw material powders were mixed with the following composition, and the mixed sample powder was wrapped in molybdenum foil.
The mixture was heated and melted at 1700 ° C. for 2 hours, and then rapidly cooled to obtain a fluorescent glass. Two types of fluorescent glasses activated with Cr ³⁺ were prepared in order to examine the uniformity of the obtained samples.

(Sample A) CaCO ₃ : Al ₂ O ₃ : SiO ₂ : AlN: Cr ₂ O
₃ = 28.3: 3.3: 33.8: 33.6: 1.0
(N: 5 wt%) (Cr: 2.0%) (Sample B) CaCO ₃ : Al ₂ O ₃ : SiO ₂ : AlN: Cr ₂ O
₃ = 28.3: 3.3: 33.8: 33.6: 1.0
(N: 5 wt%) (Cr: 2.0%)

FIG. 4 shows that Ca− doped with Cr ³⁺ ions.
1 shows an excitation / emission spectrum of an Al-Si-ON-based oxynitride glass. In FIG. 4, two types of samples (A and B) were confirmed as Cr ³⁺ -doped oxynitride glasses collected from the same batch. The excitation spectrum of Sample A is the result of measurement while monitoring emission at 470 nm. The emission spectrum was measured using 270 nm as excitation light.

On the other hand, the excitation spectrum 1 of sample B is 44
It was measured while monitoring the emission at 0 nm.
The emission spectrum 1 of B was measured using 255 nm as excitation light, and the emission spectrum 2 of B was
It was measured using 335 nm as excitation light.

Although the excitation and emission spectra of sample A are different from those of sample B, a close observation shows that each excitation spectrum has two peaks. Also,
Broad peak of emission spectrum is 350-600n
Both samples are similar, considering that they are also present in m. Note that the peak at 255 nm of the excitation spectrum is
The absorption of the base material of the fluorescent glass and the peak at 335 nm are respectively attributed to the absorption of Cr ³⁺ ions themselves.

Example 4 Example doped with Mn ^{2+ The} raw material powder was mixed with the following composition, the mixed sample powder was wrapped in molybdenum foil, and was heated at 1700 ° C. for 2 hours in a nitrogen atmosphere using a high-frequency heating furnace. The mixture was heated and melted, and then rapidly cooled to obtain a fluorescent glass. In addition, two types of fluorescent glasses in which Mn ²⁺ was activated were prepared in order to examine the uniformity of the obtained samples.

(Sample A) CaCO ₃ : Al ₂ O ₃ : SiO ₂ : AlN: MnCO
₃ = 29.9: 2.8: 33.2: 33.1: 1.0
(N: 5 wt%) (Mn: 1.0%) (Sample B) CaCO ₃ : Al ₂ O ₃ : SiO ₂ : AlN: MnCO
₃ = 29.9: 2.8: 33.2: 33.1: 1.0
(N: 5 wt%) (Mn: 1.0%)

FIG. 5 shows an excitation / emission spectrum of a Ca-Al-Si-ON-based oxynitride glass doped with Mn ²⁺ ions. From the comparison of the excitation and emission spectra of Sample A and Sample B in FIG. 5, the oxynitride glass doped with Mn ²⁺ is uniform.

[0048]

According to the phosphor of the present invention, the position of the excitation spectrum remarkably shifts to the longer wavelength side as compared with the oxide glass,
The absorption peak is around the emission peak of the blue LED (450 to 5
20 nm), and the peak width also increases. Therefore, when an InGaN-based blue LED is used as an excitation light source, it is efficiently excited when combined with this phosphor, and a brighter white LED can be realized. Also, unlike crystals like oxynitride, glass has a loose structure,
As long as the reaction conditions can be satisfied, the ratio of O to N in the oxynitride glass can be freely changed, and the multicoloring of the phosphor can be easily achieved by changing the N content.

[Brief description of the drawings]

FIG. 1 is a graph of an excitation / fluorescence spectrum showing the N content dependency of the Eu-doped oxynitride glass of the present invention.

FIG. 2 is a graph of an excitation / fluorescence spectrum showing the Eu content dependence of the Eu-doped oxynitride glass of the present invention.

FIG. 3 is a graph of an excitation / fluorescence spectrum of the Ce-doped oxynitride glass of the present invention.

FIG. 4 is a graph of an excitation / fluorescence spectrum of the Cr-doped oxynitride glass of the present invention.

FIG. 5 is a graph of an excitation / fluorescence spectrum of the Mn-doped oxynitride glass of the present invention.

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Claims (4)

[Claims] 1. In terms of mol%, CaCO ₃ is converted to CaO: 20 to 50 mol%, Al ₂ O ₃ : 0 to 30 mol%, SiO: 25 to 60 mol%, AlN: 5 to 50 mol. %, Rare earth oxide or transition metal oxide: 0.1 to 20
A phosphor whose base material is oxynitride glass whose mol% is 100 mol% in total of five components. 2. The phosphor according to claim 1, wherein the nitrogen content is 15 wt% or less. 3. A co-activator having a content of 0.1 to 10 mol% in the fluorescent glass as a rare earth oxide other rare earth element ions serving as a sensitizer in addition to the rare earth oxide ion according to claim 1. A phosphor comprising the oxynitride glass according to claim 1 as a base material. 4. A white light-emitting diode using an InGaN-based blue light-emitting diode as a light source and using the phosphor according to any one of claims 1 to 3.