JPH0543256A - Production of fluoride glass - Google Patents

Abstract

PURPOSE:To stably produce a large-sized fluoride glass of uniform composition by using a specified complex of Ba and beta-diketone and the gaseous compd. of metallic element as the starting material, mixing the material with a fluorine- contg. gas and subjecting the mixture to a reaction. CONSTITUTION:A specified complex consisting of Ba and beta-diketone is used as a first starting material and the gaseous and/or vaporizable compds. of the metallic elements such as Zr organometallic compd. as a second starting material. A fluorine-contg. gas such as the gaseous mixture of HF and F2 is used as the fluorinating agent. The starting materials are mixed with the fluorinating agent, and the mixture is introduced into a reaction system contg. a substrate. The components are allowed to react with one another in the vapor phase or on the substrate. In this case, a compd. shown by the structural formula is used as the complex. The compd. has a high vapor pressure at low temp. and is thermally stable. Consequently, the volatile raw material of Ba is stably supplied, and an optically homogeneous fluoride glass of uniform composition is formed on the substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a fluoride glass, and more particularly to a method for producing a highly optically homogeneous fluoride glass used for optical fibers, laser glasses, lenses and the like.

[0002]

2. Description of the Related Art Fluoride glass has excellent transmission characteristics in the infrared wavelength region, and is attracting attention as a material having a high possibility of realizing an extremely low loss optical fiber in the infrared wavelength region. In the case of producing such a fluoride glass, a melting method of a solid phase raw material batch has been conventionally used. In this method, the solid phase raw material is weighed, crushed and mixed,
Fluoride glass is produced by melting raw materials in batches and quenching in the batches. For this reason,
When weighing each raw material, crushing it, and mixing, mixing transition metal impurities such as Fe, Ni, Cu, Cr, and Co that have absorption in the infrared wavelength region and mixing of water that causes oxide scatterers. Adsorption occurs. Further, there is a defect that impurities are mixed due to corrosion of the batch wall when the glass is melted.

On the other hand, the vapor phase synthesis method is a synthesis method suitable for the synthesis of high-purity homogeneous glass, as is known for silica optical fibers. The vapor phase synthesis method of fluoride glass is described in Japanese Patent Application No.
As described in No. 49277, it can be prepared by a method using a β-diketone complex of Ba as a Ba source.
-Depending on the kind of the substituent of the diketone, there were drawbacks such as poor thermal stability and low vapor pressure, and stable supply could not be achieved.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a method for producing a large-sized fluoride glass having a uniform composition, which enables stable supply of a Ba source during vapor phase synthesis of fluoride glass. Especially.

[0005]

In order to solve the above problems, the present invention provides the following structural formula among the β-diketone complexes of Ba.

[Chemical 2] The compound represented by is used as the first starting material.

The β-diketone compound of Ba used in the present invention has a high vapor pressure at low temperature and is thermally stable. Can be stably supplied, and as a result, a large-sized fluoride glass having a uniform composition can be produced.

[0007]

EXAMPLES Examples of the present invention will now be described in detail, but the present invention is not limited thereto.

Example 1 FIG. 1 is a conceptual diagram showing the constitution of the apparatus used in the example as an example of the apparatus used in the method for producing a fluoride glass of the present invention, in which 1 is made of Al as a reaction system. The chamber is maintained by a rotary pump at a pressure of 10 mmHg. The entire chamber is kept at 190 ° C. by the heater 2. A substrate 3 made of CaF ₂ is installed in the chamber 1. Into this chamber 1, a gas flow of an organometallic compound and a fluorine-containing gas are introduced from inlets 1a and 1b, respectively.

In this example, Zr and CF _3- were used as starting materials.
A compound with COCH ₂ CO-CF ₃ (hereinafter abbreviated as Zr (hfa) ₄ ),
Compound of Ba and C ₂ F ₅ -COCH ₂ CO-C (CH ₃ ) ₃ (hereinafter, Ba (ppm) ₂
Abbreviated) was used.

The gases of Zr (hfa) ₄ and Ba (ppm) ₂ are vaporized by keeping the temperature at 60 ° C. and 220 ° C., respectively, and Ar is supplied as a carrier gas. That is, the inlet 1a is connected via the supply pipes 7a, 7b to the evaporators 8a, 8b filled with Zr (hfa) ₄ and Ba (ppm) ₂ , respectively.
While heating, while introducing Ar into Zr (hfa) ₄ and Ba (ppm) ₂ ,
It is supplied into the chamber 1. In addition, Zr (hfa) ₄ mentioned above
And Ba (ppm) ₂ can be adjusted by adjusting the flow rate of Ar carrier gas.

HF and F ₂ selected as fluorine-containing gas
The mixed gas of is supplied from the inlet 1b via the supply pipe 4, and the supply amounts of HF and F ₂ can be adjusted by a mass flow controller. In addition, the supply pipes 7a, 7b, and 4 are heated to 65 ° C., 195 ° C., and 30 ° C. by the heat insulation heaters 6a, 6b, and 5 in order to suppress gas condensation.
It is kept warm at ℃.

In this embodiment, Zr (hfa) ₄ is 2 cc / min.
Ba (ppm) ₂ is 1 cc / min., HF is 15 cc / min., F ₂ is 15 cc / mi.
As a result of conducting the reaction for 2 hours under the condition of n., 65 ZrF ₄ -35 BaF ₂
A 5 mm-thick glass film having the above composition could be prepared. The composition analysis in the depth direction in the glass produced in this way,
The result measured by X-ray microanalyzer (XMA) is shown in FIG. For comparison, the following structural formula is used as the Ba source.

[Chemical 3] and

[Chemical 4] The results using the metal complex represented by are also shown.

That is, in FIG. 2, A shows the composition analysis result in the film thickness direction of the glass produced in the example, and B shows the chemical formula 3.
When the compound represented by the formula (4) is used, C represents the composition analysis result in the case of the formula (4).

As is clear from FIG. 2, when Ba (ppm) ₂ was used, a glass having a uniform composition in the film thickness direction was obtained, whereas the compounds represented by Chemical formulas 3 and 4 were obtained. When used, BaF ₂ decreases in the film thickness direction. This is Ba
It is shown that (ppm) ₂ is more stably vaporized over a longer period of time than other compounds and can be continuously supplied to the reaction system.

The vaporizability and thermal decomposition stability of the β-diketone complex of Ba are determined by the two substituents contained in the β-diketone. One of the substituents - If you (CH _{3) 3,} the higher volatile as other substituents rich in fluorine. This is because the interaction between molecules can be reduced by containing a large amount of fluorine having a large ionic radius and a high electronegativity. However, on the other hand, when the content of fluorine is high, the electron density of this substituent is high, so that the electron density involved in the bond with the metal is lowered, and the decomposition by the bond dissociation of the metal and β-diketone is caused by heating. Occurs. Therefore - (CH _{3) 3} when the one of the substituents, if other substituents are not sufficient vapor pressure to obtain the is -CF _3, also is -C ₃ F ₇ heat Decomposition is likely to occur. Here, when -C ₂ F ₅ is used, a β-diketone complex of Ba which is stable even against thermal decomposition and has a high vapor pressure can be obtained.

Example 2 Example 2 is the same as Example 1 except that as shown in FIG. 1, three new evaporators similar to 8a and 8b, that is, evaporators 8c, 8d and 8e are installed. Fluoride glass was produced using the same apparatus as in 1. In the newly installed evaporator, La (ppm) ₃ ,
Al (fod) ₃ (fod: C ₃ F ₇ -COCH ₂ CO-C (CH ₃ ) ₃ and Na (ppm) are filled and heated to 180 ℃, 90 ℃ and 150 ℃ respectively, and Ar is used as carrier gas. Example 1 except that it was introduced into the reaction system
Fluoride glass was synthesized under the same conditions as above.

The synthesis time is 2 hours and is about 5.5 mm on the CaF ₂ substrate.
Of glass deposited. The composition of the obtained fluoride glass is
It was 53ZrF ₄ -20BaF ₂ -4LaF ₃ -3AlF ₃ -20NaF. As a result of measuring the Ba distribution in the film thickness direction using XMA for this glass, the variation was 0.1 atomic% or less, and it was found that the Ba source was stably supplied.

[0018]

Industrial Applicability As described above, the method for producing a fluoride glass of the present invention enables stable supply of a Ba source during vapor phase synthesis of a fluoride glass, which has been impossible in the past. Fluoride glass having a uniform composition can be manufactured as compared with the manufacturing method using a Ba source.

[Brief description of drawings]

FIG. 1 is an explanatory view conceptually showing an apparatus for producing a fluoride glass used in Example 1 of the present invention.

FIG. 2 is a composition analysis result in the film thickness direction of the glass produced in Example 1 of the present invention, and shows the results in the film thickness direction when the compound represented by Chemical formula 3 is used and when the compound represented by Chemical formula 4 is used. It is a figure which shows a composition analysis result.

[Explanation of symbols]

1 Chamber 1a Raw Material Inlet 1b Fluorine Containing Gas Inlet 2 Heater 3 CaF ₂ Substrate 4 Fluorine Containing Gas Supply Pipe 5, 6 Supply Pipe Heat Keeping Heater 7 Raw Material Supply Pipe 8 Evaporator 9 Raw Material Heating Heater 10 Raw Material β-diketone Complex

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical display location G02B 6/00 356 A 7036-2K // H01S 3/08 (72) Inventor Sugo Sugawa Tokyo Metropolitan Government 1-16 Uchisaiwaicho, Chiyoda-ku Nihon Telegraph and Telephone Corporation

Claims (1)

[Claims] 1. A complex consisting of Ba and β-diketone is used as a first starting material, a gaseous and / or evaporable compound of a metal element is used as a second starting material, and these first starting material and The second starting material and a fluorine gas used as a fluorinating agent are mixed and introduced into a reaction system provided with a substrate, and these components are reacted in a gas phase or on the substrate to give the substrate. In the above method for producing a fluoride glass, the complex consisting of Ba and β-diketone is represented by the following structural formula: A method for producing a fluoride glass, which is a compound represented by: