JPH0790268A - Production of rare earth element-containing halide transparent material - Google Patents

Abstract

PURPOSE:To obtain the transparent material excellent in luminous efficiency, durability and handleability and useful as a parent material for visible light laser-generating elements, etc., by melting a raw material, charging the melted raw material in a fine tube, and subsequently remelting the charged raw material into the transparent material. CONSTITUTION:A raw material such as anhydrous erbium chloride is melted, bubbled with a halogen gas to remove impurities, and subsequently suck-charged into the fine tube of quartz glass. The charged raw material is remelted and clarified by a band-melting method to obtain the transparent material of the formula (R1, R2 are rare earth elements; x is 0.01-1; z is 1-4).

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a rare earth-containing halide transparent body. The transparent body produced by the present invention is useful as a base material for a light wavelength up-conversion material (up-conversion), particularly a visible light laser oscillation element.

[0002]

2. Description of the Related Art Generally, in fluorescence emission, the wavelength of emitted light is longer than the wavelength of absorbed light. However, some rare earth ions exhibit fluorescence called upconversion, which emits light having a shorter wavelength than the excitation light. Although such a phenomenon has been conventionally considered to be applied as a light-emitting body of a display, a detector of infrared light, etc., recently, a visible light laser realized by converting infrared semiconductor laser light into visible light. Especially, as a base material of a blue / green light laser oscillating device, investigations are being made, and therefore, a transparent light-emitting body is required.

Various glass materials have been proposed as transparent materials exhibiting up-conversion fluorescence. For example, Japanese Patent Application Laid-Open No. 3-295828 describes an oxide glass containing a heavy metal oxide or a rare earth element oxide. Further, in JP-A-4-12035, a rare earth-containing fluoride glass containing fluorides of zirconium and barium as main components and containing lanthanum, aluminum, sodium, indium and fluorides of erbium and ytterbium is further provided. JP 4-32
In the 8191 publication, an alkali metal, each of fluorides of lithium and zirconium as a main component, erbium, any of thulium and holmium, and a rare earth-containing fluoride glass containing a fluoride of ytterbium,
Each has been proposed.

However, these materials are the light emitting source E
Since it is essentially difficult to increase the concentration of rare earth ions such as r ³⁺ , a compact light emitting device with a short optical path length cannot be obtained. Further, it is known that even if a rare earth ion is contained at a high concentration, the luminous efficiency is lowered due to a phenomenon called concentration quenching. Further, since all of them are glass materials and are produced by quenching a molten raw material, there is a big problem that it is difficult to obtain a homogeneous composition as a problem common to multi-component glasses. Further, all of the above glass materials are fluorides or oxides, but it is known that chloride or bromide is more preferable as a rare earth salt (Tabe et al., "Ceramics", 26 (1991)). ) 144). Nevertheless, fluorides and the like have been proposed because chlorides and bromides are considered to be unsuitable as practical materials because they have extremely high hygroscopicity and are difficult to synthesize and use.

It is also conceivable to use a crystalline material as a transparent material other than glass. In this case, since it is difficult to increase the transmittance of the polycrystalline body, it is practically limited to a single crystal, but the rare earth halide is a single salt (containing only a rare earth element as a cation) in the crucible. Although a single crystal of sufficient size for crystal structure analysis was obtained by melting the raw material and then slowly cooling it, most of the complex salts are of a size that can be put to practical use as a laser wavelength conversion element ( A single crystal reaching several mm square) has not been obtained. In addition, basic data such as phase diagrams and crystal structures necessary for growing single crystals have not been obtained.

[0006]

DISCLOSURE OF THE INVENTION In order to solve the above problems in the prior art, the present invention has a high rare earth ion concentration, a high luminous efficiency and a high visible light transmittance, and has a practical size and is easy to handle. Another object of the present invention is to provide a method for producing a halide transparent body containing a rare earth element.

[0007]

According to the present invention, the following method for producing a rare earth-containing halide transparent body is provided. (1) In the production of a halide containing a rare earth, after melting a raw material, filling the melt into a thin tube made of a substance inert thereto, remelting by a zone melting method to make it transparent. A method for producing a transparent halide containing a rare earth characterized. (2) After melting the raw material, a halogen gas is introduced into the melt to remove impurities, and then the melt is sucked and filled in a thin tube of quartz glass and remelted by a zone melting method to be transparent. The manufacturing method of (1). (3) The composition formula of the obtained transparent body is R1 _x R2 _(1-x) Ba _z Cl
_{3 + 2z} (where R1 and R2 are the same or different rare earth elements,
The production method according to (1) above, wherein 01 <x ≦ 1 and 1 <z <4). (4) The composition formula of the obtained transparent body is ErBa _z Cl _{3 + 2z} or Tm.
The manufacturing method of (3) above, which is Ba _z Cl _{3 + 2z} (z is the same as defined above).

The present invention provides a manufacturing method for obtaining a rare earth-containing halide as a transparent body. The method of the present invention is basically a method of applying a zone melting method to a halide material. The zone melting method itself is a method generally used for growing a single crystal of a compound having an anharmonic melting composition.
It is characterized in that it holds the melt and the resulting crystal. That is, the present invention is characterized in that the raw material is filled in a thin tube which is inactive to the raw material, and the zone melting method is applied, and at this time, the raw material is melted and filled as a melt. By adopting such a method, a transparent crystal having a size that fills the thin tube can be obtained.

The fact that the thin tube is inactive with respect to the raw material means that it does not substantially react with the raw material and the gas generated therefrom, and a dense material impermeable to moisture and oxygen is used. . It is also preferably transparent as described later. Quartz glass is an example of a material that satisfies such conditions. The inner diameter of the thin tube is preferably 6 mm or less. If a tube having a diameter larger than this is used, the crystals may crack or the quartz tube may crack due to the stress caused by the difference in thermal expansion. Further, in the filling method by siphoning described later, if the tube diameter is too large, the packing density is likely to decrease, and it becomes difficult to manufacture a transparent body having high transmittance. The pipe length is appropriately determined according to the required transparent body and the size of the heating furnace.

In the present invention, the raw material is melted and then filled in the thin tube. In the method of filling the lump or powder sample, the packing density is insufficient and stable crystal growth is difficult, and there is a possibility that the atmosphere is contaminated during the powder filling operation. There is no such problem because it is filled. In order to avoid damage to the thin tube during remelting, contamination from the atmosphere, or damage to the device due to halogen generated from the raw material, the thin tube may be vacuum-sealed in a quartz tube larger than this.

The filling of the thin tube can be carried out by various methods, but the siphoning method is particularly advantageous since the melt is used as the raw material. Specifically, suction means such as a dropper is connected to one end of the pipe to suck up the molten raw material.
It is preferable to melt the raw material and fill the tube in an inert gas atmosphere such as argon, and blow a corresponding halogen gas into the melted raw material to remove other anionic components such as impurities such as carbonate ion. It is preferable to remove by volatilization.

The zone melting method itself may be performed according to a known method. According to the present invention, the thin tube filled with the molten raw material is cooled or allowed to cool to solidify the raw material, and then a part of the side end is heated to remelt the internal raw material into a band. Then, the heated portion is moved in the longitudinal direction to gradually move the remelted portion. In the band melting method, ineffective portions are formed at both ends of the sample, so it is desirable to make the sample into a rod shape as long as possible.

It is desirable that the growth speed of the transparent body, that is, the moving speed of the raw material melting portion is 20 mm or less per hour. A growth rate higher than this tends to cause a decrease in transmittance. The temperature of the raw material melting portion depends on the target composition, but is usually about 300 to 800 ° C. in the case of a rare earth chloride system.

The transparent body obtained in the present invention is considered to be a single crystal. Although the details of the reason why the present invention can obtain a transparent crystal having a size that was difficult to produce in the related art are not clear, (i) the packing density in the capillary is high because the raw material is melted and packed, (ii) ) The use of a thin tube limits the crystal growth direction so that no axis deviation occurs. (Iii) Since the container is inert to the raw material, the collapse of the crystal due to moisture in the atmosphere is avoided. The reason is considered to be that (iv) there is a refining effect at the same time as crystal growth, and (v) some deviation from optimum values of crystal growth conditions such as temperature and composition of starting materials is allowed due to zone melting.

The composition of the rare earth-containing halide transparent body produced according to the present invention has a wide range, and it is difficult to produce a high-purity raw material, and it is also applicable to a rare earth-containing halide having poor basic data such as a phase diagram. . As an example, a rare earth-barium halide which has been difficult to produce in the past: R1 _x R2 _(1-x) Ba _z Cl _{3 + 2z} (where R1 and R2 are the same or different rare earth elements, 0.01 <x ≦ 1 , 1 <z <
The transparent crystal of 4) can be obtained. In particular, ErBa _z Cl _{3 + 2z} and TmBa which have excellent luminous efficiency for infrared light.
_z Cl _{3 + 2z} of (1 <z <4) rare earth - can be obtained transparent body barium complex chlorides.

The above rare earth-containing halide transparent body has a relatively low strength, and is easily broken when stress is applied, and the transmittance is lowered even if the stress for breaking is not applied. Further, there is a problem that it is easily decomposed by moisture and oxygen in the atmosphere. However, the transparent body produced by the present invention is already crystallized in the thin tube at the time of production because it is crystallized in the thin tube, and therefore, the thin tube is dense and has no harmful components such as moisture and oxygen. By using a transparent material, a transparent body having excellent durability and strength can be obtained.

[0017]

EXAMPLES Examples of the present invention will be shown below. It should be noted that the present embodiment is an example and does not limit the scope of the invention.

Example 1 40 g of anhydrous erbium chloride (ErCl ₃ ) and 60 g of anhydrous barium chloride (BaCl ₂ ) were filled in a glassy carbon crucible, and vacuum-argon substitution was performed in a quartz glass container. It was heated to 800 ° C in an argon atmosphere and melted. Chlorine gas was blown into this melt at a rate of about 100 ml / min for 1 hour using a quartz tube for purification. When the melt was sucked up by a quartz tube with an inner diameter of 2.5 mm after standing still for about 30 minutes, a sample of about 300 mm was sucked into the quartz tube and solidified. After vacuum-sealing this tube in a quartz tube with a large diameter, install it in a heating furnace,
The heated part was raised from the lower end at a speed of 7 mm per hour to grow a transparent body. The inside of the furnace is about 10 mm at the center of the furnace, 700 ° C,
The temperature distribution was such that the temperature dropped about 5 ° C every 1 mm from the center. Further, the lowermost end of the sample was not completely sealed, and remelting was started from a portion about 40 mm above the lower end of the thin tube. The sample obtained in this way had a total length of about 300 mm, and 120 mm near the center was transparent. A quartz tube was cut out over a length of 12 mm, the cut surface was polished, and this was further incorporated into a transparent resin, and the transmittance in the axial direction was measured. The measured value was 75% at a measurement wavelength of 700 nm. The transmittance of the transparent crystal itself is estimated to exceed 90% after subtracting the effects of scattering by the end faces and absorption by the resin. It was also observed that when this transparent body was irradiated with infrared laser light having a wavelength of 810 nm and an output of 5 mW, strong green light emission occurred inside. Further, the transparent body was taken out, pulverized, and measured by powder X-ray diffraction. As a result, as shown at the bottom of FIG. 1, ErCl ₃ and
No diffraction peak of BaCl ₂ was found, thus confirming that this crystal is not a mixture thereof but a single compound having a composition of ErBa ₂ Cl ₇ .

Example 2 Thulium oxide (Tm ₂ O ₃ ) (28 g) and graphite powder (3 g) were mixed and pelletized, and anhydrous barium chloride (BaCl 2
₂ ) 60 g was charged into a glassy carbon crucible, vacuum-argon substitution was performed in a quartz glass container, and then the temperature was raised to 1000 ° C. Chlorine gas was blown into this at 300 ml / min for 3 hours to obtain about 100 g of a thulium chloride-barium chloride mixture. Since unreacted graphite remained on the surface of this, it was scraped off after cooling, put again in a glassy carbon crucible, heated to 800 ° C in a quartz glass container to form a melt, and chlorine was added for purification. The gas was blown at 100 ml / min for 1 hour, allowed to stand for 30 minutes, and then sucked up by a transparent quartz tube having an inner diameter of 2.5 mm. In this quartz tube, as in Example 1, about 3
When a sample of 00 mm was sucked up and the same treatment as in Example 1 was performed, a transparent body of about 120 mm was obtained as in Example 1. The axial transmittance was the same as in Example 1. It was also observed that when this transparent body was irradiated with infrared laser light having a wavelength of 780 nm and an output of 5 mW, blue-green light emission occurred inside. Furthermore, when the transparent body was taken out and pulverized and measured by powder X-ray diffraction, as shown in the bottom of FIG. 2, no diffraction peaks of TmCl ₃ and BaCl ₂ were found,
It was confirmed that this crystal was not a mixture thereof but a single compound having a composition of TmBa ₂ Cl ₇ .

Examples 3 to 6 Transparent crystals having the compositions shown in Table 1 were produced in the same manner as in Examples 1 and 2, and light having a wavelength shown in Table 1 was made to enter these crystals, and their light emitting states were observed. . The results are summarized in Table 1. In the table, the results of Examples 1 and 2 are also shown as sample numbers 1 and 2.

[0021]

[Table 1] Sample composition Transmittance (%) Excitation wavelength Emission color Emission intensity 1 ErBa ₂ Cl ₇ 90 or more 810 nm Green strongest 2 TmBa ₂ Cl ₇ 90 or more 780 nm Blue green Slightly weak 3 HoBa ₂ Cl ₇ 90 or more 650 nm Green strong 4 Tm _0.2 Gd _0.8 Ba ₂ Cl ₇ 85 or more 780 nm Blue-green Normal 5 Tm _0.1 Yb _0.9 Ba ₂ Cl ₇ 85 or more 980 nm Blue-green Normal 6 Tm _0.8 Er _0.2 Ba ₂ Cl ₇ 85 or more 780 nm Green Strong

[0022]

According to the present invention, it is possible to stably produce a transparent rare earth element-containing halide having a high luminous efficiency in up-conversion. In particular, according to the production method of the present invention, a transparent crystal can be obtained in the form of being enclosed in a transparent tube, so that it can be cut out to an appropriate length and used as it is, and is required as an oscillation element for infrared laser light. A transparent body of various sizes can be easily obtained, and a highly practical semiconductor visible light laser oscillation element base material can be provided. Further, since the transparent body obtained by the production method of the present invention is covered with the transparent tube, it is easy to handle after production.

[Brief description of drawings]

1 is a powder X-ray diffraction chart of the compound of Example 1 shown in contrast to the X-ray diffraction charts of ErCl ₃ and BaCl ₂ .

FIG. 2 is a powder X-ray diffraction graph of the compound of Example 2 shown in contrast to TmCl ₃ and BaCl ₂ X-ray diffraction graphs.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuhiro Hanagami 1-297 Kitabukuro-cho, Omiya-shi, Saitama Mitsubishi Materials Corporation Central Research Laboratory

Claims (4)

[Claims] 1. In the production of a halide containing a rare earth, a raw material is melted, the melt is filled in a narrow tube made of a substance inert thereto, and then remelted by a zone melting method to be transparent. A method for producing a rare earth-containing halide transparent body, comprising: 2. After melting the raw material, a halogen gas is introduced into the melt to remove impurities, and then the melt is sucked and filled in a silica glass thin tube and remelted by a zone melting method. The manufacturing method according to claim 1, which is transparent. 3. The composition formula of the obtained transparent body is R1 _x R2 _(1-x)
Ba _z Cl _{3 + 2z} (R1 and R2 are the same or different rare earth elements, 0.01 <x
The manufacturing method according to claim 1, wherein ≦ 1, 1 <z <4). 4. The method according to claim 3, wherein the composition formula of the obtained transparent body is ErBa _z Cl _{3 + 2z} or TmBa _z Cl _{3 + 2z} (z is the same as the above definition).