JPH0859286A - Blue light emitting glass material - Google Patents

Abstract

PURPOSE: To obtain the subject glass maternal easy in vitrification large in luminous strength, and releasing blue light having strength and stability durable for practical uses by the irradiation of infrared semiconductor laser light as excitation light by adding thulium chloride to a chloride glass preform material comprising gadolinium chloride as a vitrifying agent and an alkaline earth metal chloride as a vitrifying auxiliary. CONSTITUTION: The blue light-emitting glass material comprises 35-93mol.% of gadolinium chloride, 6-49mol.% of barium chloride, and 0.05-33mol.% of thulium chloride. A Tm ion used as a luminous center emits green light by the irradiation of red excitation light. The figure shows a three-dimensional vitrification range expressing a glass material composition range comprising GdCl2 -BaCl2 -TmCl2 , and the glass material of this invention is obtained in the oblique line composition range of the figure. The chloride glass material of this invention is obtained by compounding the purified and dried chloride powder of these raw materials each in a prescribed amount with each other, heating and melting the mixture powder in a chlorine gas atmosphere or under vacuum, and subsequently quenching the melt product. The glass transition point of the vitrified material is >=200 deg.C which is higher than those of conventional chloride vitrified materials.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wavelength conversion material for converting infrared light or red light into visible light having a shorter wavelength. More specifically, it has excellent conversion efficiency and handleability, is easy to manufacture, and can be widely applied to materials for display phosphors, infrared light detectors, up-conversion lasers, etc. The present invention relates to a glass material that efficiently converts light into blue light.

[0002]

2. Description of the Related Art Generally, in fluorescence emission, the emitted light has a longer wavelength than the incident light (excitation light), but some rare earth ion-containing substances emit light having a shorter wavelength than the excitation light. There is one that shows fluorescence called. This is because the electrons of the rare earth ions are excited by two-step absorption of photons or the like. For example, a phosphor that emits visible light using infrared light as excitation light is known, and it is used as a material for identifying the optical path of infrared light that is invisible to the naked eye. It is expected to be used as a light source of a visible light laser in combination with a laser. In particular, a phosphor made of a transparent glass material has (i) little loss or scattering when visible light is generated because it is transparent, (ii) can be molded into any shape such as fiber, (iii) wavelength of excitation light Since the fluctuation of the absorption efficiency due to the fluctuation is small, there is an advantage that a relatively stable output can be obtained even when a semiconductor laser whose output wavelength is apt to change due to the influence of temperature and current is used as the excitation light.

In particular, recently, there has been a demand for an up-conversion material which emits light of a shorter wavelength corresponding to a higher density of optical storage, and a phosphor which emits blue light by using infrared light and red light as excitation light. Is under consideration. Conventionally, YLiF has been used as an up-conversion phosphor of this type.
_A blue laser oscillation was observed at 75 K due to a crystal in which ₄ crystals were doped with Tm ³⁺ (Applied Optics, 28, 1
7, 3553-3555, 1989).

However, in the case of a crystal, it is difficult to mold it into an arbitrary form such as a fiber, and it is often difficult to manufacture a large single crystal. In addition, while a crystal is easy to miniaturize when combined with a semiconductor laser, the luminescence transition probability is low due to the high symmetry of the ligand field, and since the absorption width is narrow, the wavelength of the excitation light is similar to that of a semiconductor laser. When excited by a laser that has a large fluctuation, there is a problem that the fluctuation of absorption efficiency is large. As this type of glass phosphor, a phosphor obtained by doping aluminum fluoride glass with Tm ³⁺ (J. Non-crystalline Solids, 135, 90-93, 199)
1) or a phosphor obtained by doping fluoride glass with Tm ³⁺ and further adding Yb ³⁺ as a sensitizer (Japanese Patent Laid-Open No. 5-319855).
No.) is known. In addition, fluorozirconate (ZBL
A phosphor in which Tm ³⁺ is doped to (AN) or Eu ³⁺ is further added as a sensitizer has been proposed (for example, S.
G. Grubb et al., Electron. Lett., 28, 1243, 1992).

However, the above-mentioned glass materials also have insufficient wavelength conversion efficiency at present. For example, in the above ZBLAN, the maximum energy of lattice vibration is as large as 400 to 500 cm ^-1 , but generally, when the lattice vibration energy is large, the multiphonon relaxation time becomes short (JP van der Ziel et al. J.
Appln. Phys. 60, (1986) 4262-67), wavelength conversion efficiency decreases.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems in conventional glass materials, is easy to vitrify, has a high emission intensity, and has strength and stability that can be practically used as red light semiconductor laser light as excitation light. An object is to provide a blue light emitting glass material that emits blue light.

[0007]

[Means for Solving the Problems] The present applicant has previously proposed that erbium (E
We proposed a phosphor comprising a halide containing r) ions as a luminescent source substance and gadolinium (Gd) ions as a luminescence assisting substance (Japanese Patent Application No. 5-237190). This phosphor has a characteristic that pre-excitation is unnecessary and conversion efficiency is high. As a result of further studies based on such research results, the present inventors have found that by using gadolinium chloride (Gd chloride) as a luminescence auxiliary substance together with an alkaline earth chloride as a glass forming aid, We have found a chloride glass containing Gd chloride as a glass forming agent and have proposed this as a glass material for light transmission (Japanese Patent Application No. 6-95477). The present invention provides excellent upconversion by incorporating thulium (Tm) ions as a luminescent center in a chloride glass containing Gd chloride as a main component of a glass base material and an alkaline earth chloride as a glass forming aid. A blue light-emitting glass body having characteristics was obtained.

That is, according to the present invention, there is provided a blue light emitting glass material having the following constitution. (1) A blue light emitting glass material obtained by containing thulium chloride (Tm chloride) in a chloride glass base material using Gd chloride as a glass forming agent and alkaline earth chloride as a glass forming aid. (2) The glass forming aid is Ba chloride, Sr chloride,
The above is Ca chloride or a combination of two or more thereof.
(1) blue light emitting glass material. (3) Gd 35 to 93 mol% chloride, Ba 6 to 49 chloride
The blue light-emitting glass material according to the above (2), which comprises mol% and Tm chloride of 0.05 to 33 mol%. (4) Gd chloride 48 to 83 mol%, Sr chloride 15 to 4
The blue light-emitting glass material according to (2) above, which comprises 7 mol% and Tm chloride of 0.05 to 20 mol%. (5) Gd 51-82 mol% chloride, Ca 16-4 chloride
7 mol% and Tm chloride 0.05 to 18 mol%
(2) Blue emitting glass material. (6) Gd 35 to 90 mol% chloride, Ba 1 to 48 chloride
Mol% and Sr 1 to 46 mol% chloride and Ba chloride
And the total amount of Sr chloride are 6 to 49 mol%, Tm chloride is 0.0
The blue light-emitting glass material according to (2) above, which comprises 5 to 28 mol%. (7) Gd chloride 40 to 90 mol%, Ba chloride 1 to 48
Mol% and Ca chloride of 1 to 46 mol% and Ba chloride
And the total amount of Ca chloride is 6 to 49 mol%, Tm chloride is 0.0
The blue light-emitting glass material according to (2) above, which comprises 5 to 28 mol%. (8) Gd chloride 50-83 mol%, Sr chloride 1-46
Mol% and Ca1-46 mol% Sr chloride
And Ca chloride in the total amount of 15 to 47 mol%, TmO.
The blue light-emitting glass material according to the above (2), which comprises 05 to 20 mol%. (9) Gd 35 to 91 mol% chloride, Ba 1 to 47 chloride
Mol%, Sr 1 to 46 mol% chloride and Ca 1 to 4 chloride
The blue light-emitting glass material according to the above (2), which is 6 mol% and the total amount of salt Ba, Sr chloride and Ca chloride is 7 to 49 mol% and Tm chloride is 0.05 to 30 mol%.

[0009]

DETAILED DESCRIPTION OF THE INVENTION In the glass material of the present invention, gadolinium chloride (GdCl ₃ ) is used as the glass forming agent. Since chloride glass has a lower multiphonon relaxation rate than fluoride glass, high conversion efficiency is realized in visible light conversion. Incidentally, a typical example of conventionally known chloride glass uses zinc chloride (ZnCl ₂ ) as a glass base material, but ZnCl ₂ has a remarkable deliquescent property. Gd chloride does not have such drawbacks. In the present invention, Gd chloride
Is required as the main component of the glass base material, and is at least about 40 mol%, usually 50%, in the total composition of the glass material.
It is necessary to contain more than mol%.

Since Gd chloride alone does not vitrify, a chloride glass containing Gd chloride as a glass base material has not been heretofore known. Vitrification is possible by using a certain amount of alkaline earth chloride together with Gd chloride as a glass forming aid. As the alkaline earth chloride used in combination,
Ba chloride, Sr chloride, and Ca chloride are preferable. You may use these 2 or more types together. If two or more of these are used, a more stable glass material can be obtained. Ba chloride
Is commonly used as a glass forming aid in ZnCl ₂ type glass and the like, but Ba chloride itself does not vitrify, and no example of combined use with Gd chloride has hitherto been known. A glass material composed of Gd chloride and Ba chloride was first proposed by the present inventors (Japanese Patent Application No. 6-95477). On the other hand, Sr chloride is conventionally used as a glass forming aid, but an example of using it together with Gd chloride is not known. The same applies to Ca chloride. Note that among these glass forming aids, BaCl that gives a stable glass material having the highest glass transition point.
₂ is most preferred.

Tm ions are contained in the above glass material as a luminescent center. Tm ions generate blue (about 450 to 490 nm) emission by red excitation light (excitation wavelength 677 nm). If the content of Tm ions is too small, the emission intensity becomes weak. Therefore, the amount of Tm chloride added is preferably 0.05 mol% or more, more preferably 0.1 mol% or more. On the other hand, when the amount of Tm chloride is excessive, energy transfer between ions becomes dominant, concentration quenching lowers the emission efficiency, and vitrification is hindered.
It is 0 mol%, preferably 10 mol% or less.

An example of the composition range of the blue light emitting glass material according to the present invention is shown in FIG. Figure 1 is GdCl ₃ -BaCl ₂ -
It is a ternary vitrification range showing the composition range of the glass material made of TmCl _3, and the glass material of the present invention can be obtained in the composition range of the shaded area in FIG. 1. If the composition is out of the composition range of the shaded area, the crystallization rate becomes extremely high, so that vitrification becomes difficult even with rapid cooling and devitrification (crystallization) occurs. The upper and lower limits of each component in the shaded area are GdCl ₃ 35-93.
Mol%, BaCl ₂ 6 to 49 mol%, TmCl ₃ 0.0
It is 5 to 33 mol%. In particular, Gd 52-89 mol% chloride, Ba 10-40 mol% chloride and Tm 0.1 chloride.
The emission intensity of blue light is high in the range of up to 8 mol%, and this composition range is most suitable.

In the case of GdCl ₃ --SrCl ₂ --TmCl ₃ , the following composition range is preferable. Gd chloride: 48-8
3 mol%, preferably 52 to 79 mol%, Sr chloride: 1
5 to 47 mol%, preferably 20 to 40 mol%, T chloride
m: 0.05 to 20 mol%, preferably 0.1 to 8 mol%.

In the case of GdCl ₃ --CaCl ₂ --TmCl ₃ , the following composition range is preferable. Gd chloride: 51-8
2 mol%, preferably 52-79 mol%, Ca chloride: 1
6 to 47 mol%, preferably 20 to 40 mol%, T chloride
m: 0.05 to 18 mol%, preferably 0.1 to 8 mol%.

By using two or more glass forming aids, a more stable glass material can be obtained. However, the total amount of glass forming aids is less than 50 mol%. Examples of such glass materials include Gd-Ba-Sr-Tm Gd.
-Ba-Ca-Tm or Gd-Sr-Ca-Tm quaternary system consisting of chlorides, or Gd-Ba-Sr-
A five-element system composed of each chloride of Ca-Tm can be mentioned.

GdCl ₃ --BaCl ₂ --SrCl ₂ --T
In the case of mCl ₃ , the following composition range is preferable. G chloride
d: 35 to 90 mol%, preferably 52 to 89 mol%,
Ba chloride: 1 to 48 mol%, preferably 1 to 40 mol%, Sr chloride: 1 to 46 mol%, preferably 1 to
40 mol%, Tm chloride: 0.05 to 28 mol%, preferably 0.1 to 8 mol%, and the total amount of Ba chloride and Sr chloride is 6 to 49 mol%.

GdCl ₃ --BaCl ₂ --CaCl ₂ --T
In the case of mCl ₃ , the following composition range is preferable. G chloride
d: 40 to 90 mol%, preferably 52 to 89 mol%,
Ba chloride: 1 to 48 mol%, preferably 1 to 40 mol%, Ca chloride: 1 to 46 mol%, preferably 1 to
40 mol%, Tm chloride: 0.05 to 28 mol%, preferably 0.1 to 8 mol%, and the total amount of Ba chloride and Ca chloride is 6 to 49 mol%.

GdCl ₃ --SrCl ₂ --CaCl ₂ --T
In the case of mCl ₃ , the following composition range is preferable. G chloride
d: 50 to 83 mol%, preferably 52 to 79 mol%,
Sr chloride: 1 to 46 mol%, preferably 1 to 40 mol%, Ca chloride: 1 to 46 mol%, preferably 1 to
40 mol%, Tm chloride: 0.05 to 20 mol%, preferably 0.1 to 8 mol%, and the total amount of Sr chloride and Ca chloride is 15 to 47 mol%.

GdCl ₃ --BaCl ₂ --SrCl ₂ --C
In the case of aCl ₂ -TmCl _3, the following composition range is preferable. Gd chloride: 35 to 91 mol%, preferably 52 to 8
9 mol%, Ba chloride: about 1 to 47 mol%, preferably
1 to 40 mol%, Sr chloride: about 1 to 46 mol%, preferably 1 to 40 mol%, Ca chloride: about 1 to 46 mol%,
Preferably 1-40 mol%, Tm chloride: 0.005-
30 mol%, preferably 0.1 to 8 mol%, Ba chloride,
The total amount of Sr chloride and Ca chloride is 7 to 49 mol%.

The above glass forming aids (BaCl ₂ , SrCl ₂ , Ca
Cl ₂ ) together with LiCl, NaCl, KCl, RbCl,
A more stable glass material can be obtained by using CsCl, PbCl ₂ and TlCl in combination. These additions are less than about 30 mol%. Incidentally, in addition to these glass forming aids (BaCl ₂ , SrCl ₂ , CaCl ₂ ) of the present invention, these Li
Cl, NaCl, KCl, RbCl, CsCl, PbC
The use of l ₂ and TlCl with GdCl ₃ lowers the glass transition point.

The chloride glass material of the present invention is obtained by heating and melting a mixed powder prepared by mixing a predetermined amount of purified and dried raw material chloride powder in a chlorine gas atmosphere or in a vacuum and then rapidly cooling it.
As shown in FIG. 2, the X-ray diffraction curve of the obtained quenched body does not show a sharp peak as seen in the crystalline body,
It can be confirmed that it is glassy. This is also shown in FIG.
As shown in the differential thermal analysis curve of 1., a glass transition point is recognized, which also shows that the glass is vitreous.

[0022]

EXAMPLES AND COMPARATIVE EXAMPLES Examples of the present invention are shown below together with comparative examples. It should be noted that the present embodiment is merely an example and does not limit the scope of the present invention.

Example 1 GdCl _{3 as a} glass base material and TmCl as a luminescent substance
₃ powders are commercially available Gd ₂ O _{3 with} a purity of 99.95% or more.
Alternatively, a product obtained by synthesizing Tm ₂ O ₃ by a conventional method, followed by heating and melting, blowing chlorine gas, and completely dehydrating and refining was used. Further, as the glass forming aid BaCl ₂ powder, high-purity anhydrous crystals dried in a drying container at 320 ° C. for 2 days were used. These raw material powders were mixed with GdCl ₃ 92.1 mol%, B
An ampoule was prepared by vacuum-packing a mixed powder prepared by mixing aCl ₂ 7.2 mol% and TmCl ₃ 0.7 mol% into a transparent quartz glass tube (internal diameter 1.5 mm, wall thickness 0.6 mm, length 200 mm). This was melted in a heating furnace at 600 ° C. for 15 minutes.
The obtained melt together with the ampoule was immediately cooled to 250 ° C. and gradually cooled to obtain a colorless transparent body. When this transparent body was measured by X-ray diffraction, the curve of the scattering intensity thereof was not glassy, as shown in FIG. 2, and it was confirmed that it was vitreous. Further, in the differential thermal analysis curve of this transparent body, as shown in FIG. 3, a glass transition point (Tg) was observed at around 260 ° C.,
From this measurement, it was confirmed that it was glassy.

Examples 2 to 7 The same raw materials as in Example 1 were used, and the GdCl ₃ --BaCl ₂ --TmCl ₃ mixed powder prepared in the molar ratio shown in Table 1 was treated in the same manner as in Example 1. A transparent glass material was obtained. When the obtained glass material was observed with the naked eye, no precipitation of crystals was observed inside or on the surface. Example 1
It was confirmed that the transparent body was a glass body in the same manner as in.

[0025]Examples 8-14 BaCl₂Instead of SrCl₂And the moles shown in Table 1
GdCl formulated to ratio ₃-SrCl₂-TmCl₃mixture
The powder was treated exactly as in Example 1 to form a transparent glass material.
Obtained. The raw material SrCl₂In a drying container at 320 ° C
High-purity anhydrous crystals dried for 2 days were used. Got
When observing the glass material with the naked eye, it binds both inside and on the surface.
No precipitation of crystals was observed. As in Example 1, the transparency is
It was confirmed that the bright body was a glass body.

Examples 15 to 21 GdCl ₃ -CaCl ₂ -TmCl ₃ mixed powder prepared by using CaCl _{2 in place} of BaCl ₂ and having a molar ratio shown in Table 1 was treated in exactly the same manner as in Example 1 to give a transparent glass. I got the material. As the raw material CaCl ₂ , high-purity anhydrous crystals dried in a drying container at 320 ° C. for 2 days were used. When the obtained glass material was observed with the naked eye, no precipitation of crystals was observed inside or on the surface. It was confirmed that the transparent body was a glass body in the same manner as in Example 1.

Examples 22 to 40 Using GdCl ₃ , TmCl ₃ , BaCl ₂ , SrCl ₂ and CaCl ₂ , mixed powders prepared in the molar ratios shown in Table 1 were treated in exactly the same manner as in Example 1 to give a transparent glass. I got the material. When the obtained glass material was observed with the naked eye, no precipitation of crystals was observed inside or on the surface. Example 1
It was confirmed that the transparent body was a glass body in the same manner as in.

Comparative Examples 1 to 7 Mixed powders obtained by mixing the same raw materials as those used in Examples in the molar ratios shown in Table 2 were melted by heating under the same conditions as in Example 1 and quenched. The melt was immediately devitrified and a transparent glass material could not be obtained.

[0029]

[Table 1]

[0030]

[Table 2]

Measurement of emission spectrum The glass material obtained in the example was taken out from a quartz ampoule, cut into a cylindrical shape having a length of about 5 mm, the cut portion was surface-polished to have a length of 5 mm, and then a semiconductor having a wavelength of 677 nm. The blue emission spectrum was measured by exciting with a laser (28 mW). Fluoride glass (40 AlF ₃・ 22 CaF ₂・ 22 BaF)
Samples obtained by prepared surface polishing the same shape using _{2 · 15YF 3 · 1TmF 3)} , using a tunable laser emission intensity at a wavelength 655 nm (28 mW), was measured in the same manner. The result is as shown in FIG. 4, and the glass material of the example (solid line) has a blue intensity near the wavelength of 450 nm which is about 10 times higher than that of the conventional fluoride glass (wavy line).

For the glass materials of Examples 7, 14, 21, 40 and Comparative Examples 8 to 10 (all have the same sample shape and the like as above), the blue emission intensity was measured by using the excitation light of the above wavelength. did. Fluoride glass (40 AlF ₃ · 22 C
Table 3 shows the summary values (ratio) compared with the emission intensity of aF ₂ · 22 BaF ₂ · 15YF ₃ · 1TmF ₃ ). Comparative Example 8
Glass materials Nos. 10 to 10 were prepared in the same manner as in Example 1 except that TmCl ₃ was 0.04 mol% or less.

[0033]

[Table 3]

[0034]

EFFECTS OF THE INVENTION Since the blue luminescent material of the present invention is a glass material, it is easier to manufacture as compared with a crystalline wavelength conversion material, and it is possible to make products of various shapes such as fibers. Further, since the absorption of rare earth ions is broader than that of crystals, the fluctuation of the absorption efficiency is small even if there is wavelength fluctuation of the excitation light, and thus the fluctuation of the emission efficiency is small.
Therefore, a relatively stable output can be obtained even when a semiconductor laser whose output wavelength is apt to change due to the influence of temperature or current is used as the excitation light. Further, in the present invention, since chloride of gadolinium chloride and alkaline earth metal is used as the glass base material, and the glass transition point is 200 ° C. or higher, the conventional chloride glass (glass transition point is 175 ° C.).
The glass transition point is much higher than that of

Further, the wavelength conversion glass material of the present invention has the advantage that the light conversion efficiency is far superior to the conventional fluoride wavelength conversion glass material. Therefore, it can be applied to a wide range of fields such as displays and blue lasers using the up-conversion method.

[Brief description of drawings]

FIG. 1 Gd ₂ chloride-Ba chloride-Tm chloride according to the present invention
3 is a graph showing the ternary vitrification range.

FIG. 2 is an X-ray diffraction chart of the glass material of Example--.

FIG. 3 is a graph showing a differential thermal analysis curve of the glass material of Example.

FIG. 4 is a spectrum diagram showing the emission intensity of the glass material of Example--and the conventional fluoride glass.

Claims (9)

[Claims] 1. A blue light-emitting glass material obtained by containing thulium chloride in a chloride glass base material using gadolinium chloride as a glass forming agent and alkaline earth chloride as a glass forming aid. 2. The blue light-emitting glass material according to claim 1, wherein the glass forming aid is barium chloride, strontium chloride, calcium chloride or a combination of two or more thereof. 3. Gadolinium chloride 35-93 mol%, barium chloride 6-49 mol%, and thulium chloride 0.05-
The blue light-emitting glass material according to claim 2, comprising 33 mol%. 4. The blue light-emitting glass material according to claim 2, comprising 48 to 83 mol% of gadolinium chloride, 15 to 47 mol% of strontium chloride and 0.05 to 20 mol% of thulium chloride. 5. Gadolinium chloride 51-82 mol%, calcium chloride 16-47 mol% and thulium chloride 0.0.
The blue light-emitting glass material according to claim 2, comprising 5 to 18 mol%. 6. Gadolinium chloride 35 to 90 mol%, barium chloride 1 to 48 mol%, and strontium chloride 1 to
46 mol%, the total amount of barium chloride and strontium chloride is 6 to 49 mol%, thulium chloride 0.05 to 2
The blue light-emitting glass material according to claim 2, which comprises 8 mol%. 7. Gadolinium chloride 40-90 mol%, barium chloride 1-48 mol% and calcium chloride 1-46.
Mol%, the total amount of barium chloride and calcium chloride is 6 to 49 mol%, thulium chloride 0.05 to 28 mol%
The blue light emitting glass material according to claim 2. 8. Gadolinium chloride 50 to 83 mol%, strontium chloride 1 to 46 mol%, and calcium chloride 1
-46 mol%, the total amount of strontium chloride and calcium chloride is 15-47 mol%, thulium chloride 0.0
The blue light-emitting glass material according to claim 2, which comprises 5 to 20 mol%. 9. Gadolinium chloride 35-91 mol%, barium chloride 1-47 mol%, strontium chloride 1-46.
3. The blue light-emitting glass material according to claim 2, wherein the total amount of barium chloride, strontium chloride, and calcium chloride is 7 to 49 mol% and thulium chloride is 0.05 to 30 mol%. .