JPH08217489A - Wavelength conversion glass material - Google Patents

Abstract

(57) [Summary] [Structure] Chloride glass base material containing gadolinium chloride as a glass forming agent and alkaline earth chloride as a glass forming aid, containing thulium chloride as a luminescent center source and ytterbium chloride as a sensitizer. Wavelength conversion glass material. [Effect] The light conversion efficiency in the blue region is remarkably superior to that of the conventional fluoride-based wavelength conversion glass material, and moreover, it is easier to manufacture than the crystalline wavelength conversion material.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention is infrared light (960 to 1100 nm).
The present invention relates to a wavelength conversion material that converts visible light into a shorter wavelength visible light. More specifically, the present invention relates to a wavelength conversion glass material which is excellent in conversion efficiency and handleability, is easy to manufacture, and can be widely applied to materials for display phosphors, infrared light detectors, up-conversion lasers and the like.

[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 of a shorter wavelength than the excitation light by up-conversion. Some exhibit fluorescence.
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,
In addition to being used as a material for identifying the optical path of infrared light that is invisible to the naked eye, it is also used for display phosphors, or
It is expected to be used as a compact visible light laser light source in combination with a semiconductor laser in the infrared or red region.

In particular, recently, an up-conversion material that emits light of a shorter wavelength has been sought in response to higher density of optical storage, and a phosphor that emits blue light by using infrared light or red light as excitation light has been demanded. Consideration is in progress. For example,
Blue light emission due to up-conversion has been observed with a substance containing Yb ³⁺ and Tm ³⁺ in aluminum fluoride glass (J. Appl. Phys., 74 , No. 7, 4703f, 199).
3). However, it is difficult to mold a crystal into an arbitrary shape such as a fiber, and it is often difficult to manufacture a large single crystal. In addition, the crystal has a high symmetry of the ligand field, so the luminescence transition probability is low, and the absorption width is narrow. Therefore, when excited by a laser such as a semiconductor laser in which the wavelength of the excitation light is likely to change, absorption occurs. There is a problem that the fluctuation of efficiency is large.

Therefore, in recent years, amorphous, that is, glassy phosphors have been proposed. Phosphors made of transparent glass material, (i) easy to produce a material with less loss and scattering during visible light generation than crystals, (ii) can be molded into any shape such as fiber, and (iii) Since the fluctuation of the absorption efficiency due to the fluctuation of the wavelength of the excitation light is small, there is an advantage that a relatively stable output can be obtained even when a semiconductor laser whose output wavelength is easily changed due to the influence of temperature or current is used as the excitation light. is there. As this type of glass phosphor, a phosphor in which zirconium fluoride glass is doped with Ho ³⁺ is known, and there is a reported example of green laser oscillation at room temperature (Electron. Lett., 26 , 261-263). , 1990), or a phosphor obtained by doping a fluoride glass with Tm ³⁺ and further adding Yb ³⁺ as a sensitizer (JP-A-5-319855). In addition, ZBLAN (glass containing zirconium fluoride as a main component from each fluoride of Zr, Ba, La, Al and Na) is doped with Tm ³⁺ , or Eu ³⁺ is further added as a sensitizer. Phosphors have been proposed (for example, S.
G. Grubb et al., Electron. Lett., 28, 1243, 1992).

However, in consideration of application to visible light laser oscillation, the above glass material is insufficient in wavelength conversion efficiency from excitation light to upconversion fluorescence. That is, in the fluoride glass, the maximum energy of lattice vibration is as large as 400 to 500 cm ⁻¹ even in the above ZBLAN, but generally, when the lattice vibration energy is large, there is a problem that the multiphonon relaxation time becomes short (JP van der Ziel et.
al. J. Appln. Phys. 60, (1986) 4262-67). That is,
The electrons of the light-emitting source ion are excited by receiving excitation energy directly or through the sensitizer, but when the lattice vibration energy is large, the average residence time at the excitation level is short, and therefore the excitation is further increased. A two-step excitation process in which energy is absorbed and excited to a higher energy level is less likely to occur, and up-conversion efficiency decreases.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves the above problems in up-conversion glass useful as a wavelength conversion material, is easy to vitrify, and has a strong emission intensity.
An object of the present invention is to provide a wavelength conversion glass material that emits blue light with intensity and stability that can be practically used even when infrared laser light of nm is used as excitation light.

[0007]

According to the present invention, gadolinium chloride (GdCl ₃ : G chloride) which uses chloride glass as a base material in place of conventionally known fluoride glass and does not vitrify alone is used.
d) is used as a glass base material, and by incorporating therein thulium (Tm) ions as a luminescence center and ytterbium (Yb) ions as a sensitizer, a wavelength conversion glass material having a strong blue emission intensity is achieved. is there. Gd chloride
Since it does not vitrify alone, conventionally, a chloride glass having Gd chloride as a base material has not been known, but the present inventors have found that the use of an alkaline earth chloride as a glass-forming auxiliary causes We found that we can obtain (Patent application
6-95477). According to the present invention, based on the above-mentioned findings, the emission intensity in the blue wavelength region is high by containing Tm ion of the emission center and ytterbium (Yb) ion of the sensitizer in this Gd-alkaline earth chloride glass. It has been found that a glass material can be obtained. The present invention provides a wavelength conversion glass material that solves the conventional problems based on the above findings.

That is, according to the present invention, the following wavelength conversion glass material is provided. (1) Wavelength conversion glass obtained by adding thulium chloride as a luminescence center source and ytterbium chloride as a sensitizer to a chloride glass base material using gadolinium chloride as a glass forming agent and alkaline earth chloride as a glass forming aid Material. (2) The content of thulium chloride is 0.01 to 5 mol%, the content of ytterbium chloride is 1 mol% or more, and the concentration of ytterbium chloride is 6 times or more that of thulium chloride. (1) Wavelength conversion glass material. (3) The wavelength conversion glass material according to the above (1), wherein the glass forming aid is one kind or a combination of two or more kinds of barium chloride, strontium chloride and calcium chloride. (4) The wavelength conversion glass material according to (2) above, which comprises 40 to 88 mol% of gadolinium chloride, 10 to 45 mol% of barium chloride, and 30 mol% or less of the total amount of thulium chloride and ytterbium chloride. (5) The above (2), which comprises 50 to 78 mol% of gadolinium chloride, 20 to 40 mol% of strontium chloride, and a total amount of thulium chloride and ytterbium chloride of 19 mol% or less.
Wavelength conversion glass material. (6) The wavelength conversion glass material according to the above (2), which comprises 50 to 78 mol% of gadolinium chloride, 20 to 40 mol% of calcium chloride, and 17 mol% or less in total of thulium chloride and ytterbium chloride. (7) The wavelength conversion glass material according to the above (2), which comprises 40 to 88 mol% of gadolinium chloride, 10 to 45 mol% of the total amount of barium chloride and strontium chloride, and 30 mol% or less of the total amount of thulium chloride and ytterbium chloride. (8) Gadolinium chloride 40 to 88 mol%, total amount of barium chloride and calcium chloride 10 to 45 mol%, and total amount of thulium chloride and ytterbium chloride 30 mol%
The wavelength conversion glass material of (2) above, consisting of: (9) Gadolinium chloride 50 to 78 mol%, the total amount of strontium chloride and calcium chloride 20 to 40 mol%,
And the total amount of thulium chloride and ytterbium chloride 19
The wavelength conversion glass material according to the above (2), which comprises less than or equal to mol%. (10) Gadolinium chloride 40 to 88 mol%, total amount of barium chloride, strontium chloride and calcium chloride 1
The wavelength conversion glass material according to the above (2), which comprises 0 to 45 mol% and a total amount of thulium chloride and ytterbium chloride of 30 mol% or less.

[0009]

[Detailed Description] In the glass material of the present invention, Gd chloride is used as a glass forming agent. Gd chloride is required in an amount as the main component of the glass base material, and accounts for at least about 35 mol% and usually 50 mol% or more of the total composition of the glass material. 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 a conventionally known chloride glass uses zinc chloride (ZnCl ₂ ) as a glass base material, but zinc chloride has a practical difficulty in that it has a remarkable deliquescent property. The glass material of the present invention containing Gd chloride as a base material does not have such a defect.

As described above, Gd chloride does not vitrify by itself, but as the present inventors have clarified in Japanese Patent Application No. 6-95477, a certain amount of alkaline earth chloride is added together with Gd chloride to glass. Gd chloride can be vitrified by using it together as a 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 zinc chloride type glass and the like, but Ba chloride itself does not vitrify, and a combined use thereof with Gd chloride has not heretofore been known. A glass material composed of Gd chloride and Ba chloride was first proposed by the present inventors (the above-mentioned Japanese Patent Application No. 6-95477).
issue). 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. Among these glass forming aids, Ba chloride is most preferable because it provides a stable glass material having the highest glass transition point.

The glass material contains Tm ions as the emission center and Yb ions as the blue sensitizer.
The Tm ion becomes an emission center that produces blue light (about 450 nm to 490 nm). Since Yb ions have a large ability to capture incident light and transfer energy to Tm ions, the glass material of the present invention realizes blue light emission by using infrared light of 960 to 1100 nm as excitation light. Tm ion content is 0.01 in terms of Tm chloride
It is preferably from 5 mol% to 5 mol%. If it is less than 0.01 mol%, the concentration is too low to obtain sufficient emission intensity.
If it exceeds 5 mol%, concentration quenching is accompanied. Usually, it is preferably 0.05 mol% or more and 1 mol% or less. On the other hand, if the content of Yb chloride is large, a sufficient sensitizing effect can be obtained, and at least 1 mol% or more in terms of Yb chloride is preferable. If it is less than 1 mol%, a sufficient sensitizing effect cannot be obtained. Usually, 6 mol% or more is preferable. The total amount of Tm chloride and Yb chloride is 3
It is preferably 0 mol% or less. If it exceeds 30 mol%, the crystallization rate will rapidly increase, and it will be difficult to obtain a glass transparent body. The amount ratio of Yb chloride to Tm chloride is preferably 6 times or more. If the amount is less than 6 times, the blue sensitizing effect due to Yb chloride is not exerted sufficiently. It is more preferable that the amount is 10 times or more.

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 system graph showing the vitrification range in the system composed of (Tm, Yb) Cl ₃ , and the glass material of the present invention is obtained in the composition range of the shaded portion in FIG. 1. As is clear from the figure, the Tm ion and the Yb ion are emission centers or sensitizers. When this content is increased, vitrification of Gd chloride and Ba chloride is hindered. Since there is no great difference between the Tm ion and the Yb ion in the influence on the glass form performance, the total amount of these is shown in FIG. Although there is some variation depending on the content ratio of Tm ions and Yb ions, if it deviates from the composition range of the shaded area, the crystallization rate becomes very high, and vitrification becomes difficult even if the raw material is rapidly cooled after heating and melting. Transparent (crystallize). G in the shaded area
dCl _3: 40~88 mol%, BaCl _2: 10~45
The total amount of mol%, TmCl ₃ and YbCl _3: 1.01~
30 mol% or less is suitable. Especially, Gd40 ~
73.95 mol%, Ba chloride 20-35 mol% and T chloride
When the total amount of m and Yb is 6.05 to 30 mol%, the emission intensity of blue light is high, and this composition range is most suitable.

In the present specification and the accompanying drawings, the glass composition is represented by chlorides such as GdCl ₃ , BaCl ₂ and TmCl ₃ , which are cations (Gd ion and Ba ion etc. and Tm in the glass). (Ion and Yb ion) and anion (chloride ion) content ratios are shown in terms of chloride, and the glass-forming components form a network structure in which they are mutually bonded in the same manner as a normal glass structure.

With respect to the glass material of the present invention, the preferable composition range when Sr chloride and Ca chloride are used as glass forming aids instead of Ba chloride is shown below. _{(1) GdCl 3 -SrCl 2 -TmCl} 3 -YbCl 3 chloride Gd: 50 to 78 mol%, preferably 51 to 70 mol% chloride Sr: 20 to 40 mol%, preferably 20 to 30 mol% chloride Tm + chloride Yb : 1.01 to 19 mol%, preferably 6.05
~ 19 mol%

(2) GdCl ₃ -CaCl ₂ -TmCl ₃ -YbCl ₃ Gd chloride: 50 to 78 mol%, preferably 53 to 70 mol% Ca chloride: 20 to 40 mol%, preferably 20 to 30 mol% Tm + Yb chloride: 1.01 to 17 mol%, preferably 6.05
~ 17 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-Yb, G
d-Ba-Ca-Tm-Yb or Gd-Sr-Ca
Examples include a quaternary glass made of each chloride of -Tm-Yb and a quaternary glass made of each chloride of Gd-Ba-Sr-Ca-Tm-Yb.

With respect to the glass material of the present invention, a suitable composition range in the case of containing two or more kinds of these glass forming aids is shown below. _{(3) GdCl 3 -BaCl 2 -SrCl} 2 -TmCl 3 -YbCl 3 chloride Gd: 40 to 88 mol%, preferably from 40 to 73.95
Mol% Tm chloride + Yb chloride: 1.01 to 31 mol%, preferably 6.05
~ 30 mol% Ba chloride + Sr chloride: 10 to 45 mol%, preferably 2
0-35 mol%

[0018] _{(4) GdCl 3 -BaCl 2 -CaCl} 2 -TmCl 3 -YbCl 3 chloride Gd: 40 to 88 mol%, preferably from 40 to 73.95
Mol% Tm chloride + Yb chloride: 1.01 to 30 mol%, preferably 6.05
~ 30 mol% Ba chloride + Ca chloride: 10 to 45 mol%, preferably 2
0-35 mol%

[0019] _{(5) GdCl 3 -SrCl 2 -CaCl} 2 -TmCl 3 -YbCl 3 chloride Gd: 50 to 78 mol%, preferably 51 to 70 mol% chloride Tm + chloride Yb: from 1.01 to 19 mol%, preferably from 6.05
-19 mol% Sr chloride + Ca chloride: 20-40 mol%, preferably 2
0-30 mol%

[0020] _{(6) GdCl 3 -BaCl 2 -SrCl} 2 -CaCl 2 -TmCl 3 -YbCl 3 chloride Gd: 40 to 88 mol%, preferably from 40 to 73.95
Mol% Tm chloride + Yb chloride: 1.01 to 30 mol%, preferably 6.05
~ 30 mol% Ba chloride, Sr chloride, Ca chloride total amount: 10-45 mol%, preferably 20-35 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. The addition amount of these is about 40 mol% or less. In addition, the glass forming aid (Ba
Cl ₂ , SrCl ₂ , CaCl ₂ ) together with these LiCl and NaC
l, KCl, RbCl, CsCl, PbCl ₂ and T
The introduction of lCl into the glass composition 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 chloride powder as a raw material under a chlorine gas atmosphere or under vacuum and then rapidly cooling it to a temperature below the glass transition point. The cooling rate is 60 K / s or more. If the cooling rate is less than the above value, devitrification may occur due to some crystal formation. As shown in FIG. 2, the X-ray diffraction curve of the obtained quenched body does not show a specific peak as seen in the crystalline body, which shows that it is vitreous. Further, no peaks corresponding to the composition of each raw material salt were observed, and it can be confirmed that these are not simply mixtures of these. Further, a glass transition point is recognized as illustrated in the differential thermal analysis curve of FIG. 3, and it can be seen that it is also glassy. The glass of the present invention can be produced by a known amorphous forming method such as a vapor phase growth method in addition to the above-described melt cooling process.

[0023]

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 and TmCl ₃ powders of glass base material and YbC
As the l ₃ powder, those obtained by synthesizing commercially available Gd ₂ O ₃ , Tm ₂ O ₃ or Yb ₂ O ₃ by a conventional method, followed by heating and melting and blowing chlorine gas to completely dehydrate and purify were used. As the glass forming aid BaCl ₂ , 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 40.5 mol% and BaCl
₂ 44.5 mol%, TmCl ₃ 0.1 mol%, YbCl
_{3 The} mixed powder prepared in the ratio of 14.9 mol% was vacuum sealed in a transparent quartz glass tube (inner diameter 1.5 mm, wall thickness 0.6 mm, length 200 mm) to make an ampoule, which was heated to 600 ° C in a heating furnace. Melted for 15 minutes. The obtained melt together with the ampoule was immediately cooled to 240 ° C. (cooling rate 80 K / s), annealed for 2 hours, and then gradually cooled at 1 K / min to obtain a colorless transparent body. When the obtained transparent body was visually inspected, no precipitation of crystals was found inside or on the surface.
Further, when the 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. . Furthermore, the differential thermal analysis curve of this transparent material shows that the glass transition point (Tg) at around 250 ° C. as shown in FIG.
Was confirmed, and it was confirmed from this measurement that it was vitreous.

Examples 2-37 The same GdCl ₃ , BaCl ₂ , and TmCl _{3 as in} Example 1
And YbCl ₃ powder, SrCl ₂ and CaCl ₂ powder treated in the same manner as in Example 1 were blended in the molar ratio shown in Table 1, and the mixed powder was treated in the same manner as in Example 1 to prepare the following glass material. Got _{GdCl 3 -BaCl 2 -TmCl 3 -YbCl 3} GdCl 3 -SrCl 2 -TmCl 3 -YbCl 3 GdCl 3 -CaCl 2 -TmCl 3 -YbCl 3 GdCl 3 -BaCl 2 -SrCl 2 -TmCl 3 -Y
_{bCl 3 GdCl 3 -SrCl 2 -CaCl 2} -TmCl 3 -Y
_{bCl 3 GdCl 3 -CaCl 2 -BaCl 2} -TmCl 3 -Y
bCl _{3 The} obtained glass material was transparent, and when 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.

[0026]

[Table 1]

Measurement of Emission Spectra The glass material obtained in Example 5 was taken out from a quartz ampoule, cut into a cylinder having a length of about 5 mm, and the cut portion was surface-polished. A sample having a wavelength of 980 nm and a semiconductor laser (20 mW) was polished. Upon irradiation, it was confirmed that blue light was emitted inside the glass material.
This emission spectrum is shown by the solid line in FIG. The fluoride glass produced by a conventional method _{(22.0AlF 3 · 11.0 ZrF 4 ·} 1
0.0 YF ₃・ 12.0 CaF ₂・ 2.2 MgF ₂・ 11.1 SrF ₂・ 9.6 B
aF ₂ · 3.0NaF · 19.0 YbF ₃ · 0.1TmF ₃ ) was prepared in the same shape, cut and surface-polished. The results are as shown in FIG. 4 (broken line), and the glass material of this example exhibits strong blue light emission near the wavelength of 480 nm, and this intensity is about 10 times higher than that of the conventional fluoride glass. When the samples of the other Examples were also measured in the same manner, the blue light intensity near the wavelength of 480 nm was about 3 to 10 times that of the above-mentioned fluoride glass as in Example 1. The results are summarized in Table 1.

[0028]

Since the wavelength conversion material of the present invention is a glass material, it is easier to manufacture than a crystalline wavelength conversion material, and can be processed into various shaped products such as fibers. Further, since the absorption width is broad, the fluctuation of the absorption efficiency is small even if the wavelength of the excitation light fluctuates, 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 Gd chloride and a chloride of an alkaline earth metal are used as the glass base material, and the glass transition point is 200 ° C. or higher, the conventional chloride glass (glass transition point is about 175 ° C.) Glass transition point is much higher than that of, and it is stable. Furthermore, the wavelength conversion glass material of the present invention has, as its greatest feature, a markedly higher light conversion efficiency in the blue region than conventional fluoride wavelength conversion glass materials. 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 shows Gd ₂ -chloride-Ba-chloride (T) according to the present invention.
The graph which shows the vitrification range of m, Yb).

FIG. 2 is an X-ray diffraction chart of the glass material of Example 1.

FIG. 3 is a graph showing a differential thermal analysis curve of the glass material of Example 1.

FIG. 4 is a spectrum diagram showing the emission intensity of the glass material of Example 5 and a conventional fluoride glass.

Claims (10)

[Claims] 1. A wavelength obtained by containing thulium chloride as a luminescence center source and ytterbium chloride as a sensitizer in a chloride glass base material using gadolinium chloride as a glass forming agent and alkaline earth chloride as a glass forming auxiliary agent. Converted glass material. 2. The thulium chloride content is 0.01 to 5 mol%, and the ytterbium chloride content is 1 mol%.
The wavelength conversion glass material according to claim 1, wherein the ytterbium chloride concentration is at least 6 times that of thulium chloride. 3. The wavelength conversion glass material according to claim 1, wherein the glass forming aid is one or a combination of two or more of barium chloride, strontium chloride and calcium chloride. 4. Gadolinium chloride in an amount of 40 to 88 mol%, barium chloride in an amount of 10 to 45 mol%, and a total amount of thulium chloride and ytterbium chloride in an amount of 30 mol% or less.
Wavelength conversion glass material. 5. The wavelength conversion glass material according to claim 2, wherein gadolinium chloride is 50 to 78 mol%, strontium chloride is 20 to 40 mol%, and the total amount of thulium chloride and ytterbium chloride is 19 mol% or less. 6. The wavelength conversion glass material according to claim 2, wherein gadolinium chloride is 50 to 78 mol%, calcium chloride is 20 to 40 mol%, and the total amount of thulium chloride and ytterbium chloride is 17 mol% or less. 7. The wavelength conversion glass material according to claim 2, comprising 40 to 88 mol% of gadolinium chloride, 10 to 45 mol% of the total amount of barium chloride and strontium chloride, and 30 mol% or less of the total amount of thulium chloride and ytterbium chloride. . 8. Gadolinium chloride 40 to 88 mol%, total amount of barium chloride and calcium chloride 10 to 45 mol%,
And the total amount of thulium chloride and ytterbium chloride 30
3. The wavelength conversion glass material according to claim 2, which comprises less than or equal to mol%. 9. The wavelength conversion glass material according to claim 2, comprising 50 to 78 mol% of gadolinium chloride, 20 to 40 mol% of the total amount of strontium chloride and calcium chloride, and 19 mol% or less of the total amount of thulium chloride and ytterbium chloride. . 10. The wavelength according to claim 2, which comprises 40 to 88 mol% of gadolinium chloride, 10 to 45 mol% of total amount of barium chloride, strontium chloride and calcium chloride, and 30 mol% or less of total amount of thulium chloride and ytterbium chloride. Converted glass material.