JP3051638B2 - Method for producing glass containing Sm ions - Google Patents

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 Sm ²⁺ ion-containing glass. Sm obtained by the method of the present invention
²⁺ ion-containing glass is used as a glass material used in the optical information field such as hole burning and laser.

[0002]

2. Description of the Related Art Glass containing rare earth elements such as Nd and Er is used as a material for lasers and the like. The valence of the rare earth element is hardly affected by the surrounding matrix, and most of them exist in a trivalent state.

Recently, a permanent photochemical hole burning (hereinafter, referred to as PHB) phenomenon has been found in a halide crystal containing divalent ions such as Sm ²⁺ ions. Its development is drawing attention.

[0004] If a glass having such a PHB phenomenon is obtained, various applications can be made by utilizing the excellent properties of the glass, such as transparency, moldability, and mass productivity.

[0005] Glass is usually produced by melting a raw material and then solidifying it by cooling. However, the valence state of the rare earth element in the glass melt is hardly affected by the matrix, and generally, trivalent in glass. Exists in the state of.

However, Sm ²⁺ ions are SrF ₂ , BaF ₂
It is known that it exists in some fluorides such as Sm ²⁺ ion-containing glass using fluoride glass as a matrix. And in "Functional Materials", Volume 13, No. 5 published in May 1993, pages 12-18,
It is described that Sm ²⁺ ion-containing fluoride glass exhibits PHB phenomenon.

[0007] Further, there has been reported an example of producing a limited borate glass containing Sm ²⁺ ions.

When producing such Sm ²⁺ ion-containing fluoride glass or Sm ²⁺ ion-containing borate glass,
Adjustment of manufacturing conditions is important, and melting in a particularly strong reducing atmosphere is indispensable.

[0009] Among the above two types of glasses, in the case of borate glass, since it is an oxide, Sm ²⁺ ions are easily oxidized, and it is not easy to select the manufacturing conditions.

[0010] Expression of PHB phenomenon of Sm ²⁺ ions, ⁷ F _i → ⁵ D _j transition 3f ⁶ (680~750nm
Is performed using light absorption and emission in the wavelength region of
3f ⁵ 4d level of sm ²⁺ ions less, may be seen also f-d transition in order not large, in particular fluorides and borate glasses obtained by the matrix, the f
Since the -d transition is in the visible light range, the efficiency of the ff transition is lowered, which is not preferable. Further, such glass has poor weather resistance (chemical durability), and has many problems as a practical glass.

In order to obtain a glass having excellent weather resistance (chemical durability), instead of fluoride or borate glass, S
Desirably, it is a silicate glass containing iO ₂ as a main component.

JP-A-2-145453 discloses that Sm
It is described that ₂ ⁺ -containing quartz (SiO ₂ ) glass exhibits PHB phenomenon.

[0013]

However, Sm ²⁺ ions are unstable in a quartz matrix glass, and the Sm ²⁺ ion-containing quartz glass has a weak PHB phenomenon and no reproducibility of the PHB phenomenon. There was a disadvantage.

Accordingly, the object of the present invention is to provide
No. 45453, which solves the shortcomings of the Sm ²⁺ ion-containing quartz glass, has excellent weather resistance (chemical durability), and has an ff
It is an object of the present invention to provide a method for producing a Sm ²⁺ ion-containing silicate glass capable of expressing a strong PHB phenomenon with good reproducibility by improving transition efficiency.

[0015]

Means for Solving the Problems In order to achieve the above object, the present inventors have conducted intensive studies. As a result, a heat treatment of an aluminosilicate glass precursor containing Sm ³⁺ ions in a reducing atmosphere is carried out. Vitrify the precursor,
Sm ²⁺ and obtained by reduction of the Sm ³⁺ ion in Sm ²⁺ ion
The ion-containing aluminosilicate glass is (i) particularly excellent in weather resistance (chemical durability) among silicate glasses, (ii) excellent in Sm ²⁺ ion stability, and f−
It has been found that a strong PHB phenomenon can be expressed with good reproducibility by improving the efficiency of f transition.

Accordingly, the present invention provides a method of vitrifying a glass precursor by heat-treating an Sm ³⁺ ion-containing aluminosilicate glass precursor in a reducing atmosphere.
S the Sm ³⁺ ions are reduced to Sm ²⁺ ions, characterized in that to obtain a Sm ²⁺ ion-containing aluminosilicate glass
The gist is a method for producing a glass containing m ²⁺ ions.

Hereinafter, the present invention will be described in detail. In the present invention, an aluminosilicate glass precursor is used as a raw material of the matrix glass. Here, the aluminosilicate glass precursor means a substance before it becomes an aluminosilicate glass by heat treatment. The aluminosilicate glass precursor is not limited to this, but is preferably a solidified gel produced by a sol-gel method using an alkoxide of silicon and an alkoxide of aluminum.

Examples of silicon alkoxides include silicon tetraalkoxides such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane and tetrabutoxysilane, and methyltrimethoxysilane, vinyltriethoxysilane, γ-glycidoxypropyltrisilane. Silicon alkoxide derivatives such as methoxysilane are used.

Examples of aluminum alkoxides include aluminum trialkoxides such as trimethoxyaluminum, triethoxyaluminum, tripropoxyaluminum, tributoxyaluminum, and triamiroxyaluminum; aluminum diisopropoxide ethyl acetate chelate; Aluminum alkoxide derivatives such as secondary butoxide ethyl acetoacetate chelate.

Next, a method for producing an aluminosilicate glass precursor (solidified gel) by a sol-gel method using the above silicon alkoxide and aluminum alkoxide will be described.

In the above two types of alkoxides, aluminum alkoxides have a significantly higher hydrolysis rate than silicon alkoxides. Therefore, if they are simply mixed and hydrolyzed, aluminum alkoxides are selectively hydrolyzed to obtain a homogeneous alkoxide. Sol or gel solidified body cannot be obtained.

There are two methods for preventing the selective hydrolysis of the aluminum alkoxide to obtain a homogeneous sol or gel. One method utilizes the fact that the hydrolysis rate of an alkoxide is affected by the number of carbon atoms of an alkyl group, and generally the hydrolysis rate decreases as the number of carbon atoms increases (conversely, the hydrolysis rate increases as the number of carbon atoms decreases). I do. For example, as alkoxides of aluminum, amiloxide and butoxide,
And as a silicon alkoxide, using methoxide and ethoxide, by careful hydrolysis,
A homogeneous sol or gel solid can be prepared. Another method is a method in which a silicon alkoxide having a low hydrolysis rate is partially hydrolyzed in advance and then reacted with an aluminum alkoxide. According to this method,
Since the alkoxide of silicon and the alkoxide of aluminum have reacted before the subsequent hydrolysis, a uniform sol or gel solidified body can be obtained without causing selective hydrolysis.

It is particularly preferable to use the above two methods in combination, and an example of the combination of the two methods will be described below.

First, an alkoxide of silicon such as tetraethoxysilane is added to a mixed solution of an aqueous solution of an acid catalyst such as hydrochloric acid, nitric acid, and acetic acid and an alcohol such as ethanol.
Stir to obtain a partial hydrolyzate of the silicon alkoxide.

Next, an aluminum alkoxide such as aluminum tributoxide is added to the partially hydrolyzed solution, and the mixture is heated with stirring to react the aluminum alkoxide with the partially hydrolyzed silicon alkoxide.

Next, if necessary, an aqueous solution of an acid catalyst such as hydrochloric acid, nitric acid or acetic acid or an aqueous solution of a base catalyst such as ammonia or choline and an alcohol such as ethanol are further added, and the mixture is stirred and made of polypropylene or polymethylpentene. Transfer to a container made of plastic and leave at room temperature. By this standing, hydrolysis proceeds further and gelation occurs.

Next, by drying the gel, excess water and organic solvent are volatilized to obtain a solidified gel. In the present invention, the solidified gel obtained above can be used as an aluminosilicate glass precursor.

In this aluminosilicate glass precursor, the composition ratio of Al ₂ O ₃ and SiO ₂ is Al ₂ O ₃
Is preferably 1 to 40 mol%, and SiO ₂ is 99 to 60 mol%. The reason is as follows. That is, if Al ₂ O ₃ is less than 1 mol%, Sm ³⁺ ions contained in this aluminosilicate matrix glass are hardly reduced to Sm ²⁺ ions by the reduction treatment described later, and even if they are temporarily reduced. occurs agglomeration of Sm ²⁺ ions, of Sm ²⁺ ions ⁷ F- ⁵ D emission by transition hardly expressed. Also, when Al ₂ O ₃ exceeds 40 mol%, SiO 2
If the content of ₂ is less than 60 mol%, crystallization occurs during heating and it is difficult to obtain a transparent glass, and cracks or the like are apt to occur in the solidified gel during production. It is particularly preferred that Al ₂ O ₃ is 5 to ₃₀ mol% and SiO ₂ is 95 to 70 mol%.

The aluminosilicate glass precursor used in the present invention may be any of alkali metal oxides, alkaline earth metal oxides, boron oxides, titanium oxides, zirconium oxides and the like as long as the object of the present invention is not impaired. The oxide can be included up to 30 mol% on an outer basis with respect to 100 mol% of the total amount of Al ₂ O ₃ and SiO ₂ .

In the present invention, an Sm ³⁺ ion is contained in the aluminosilicate glass precursor.
An aluminosilicate glass precursor containing m ³⁺ ions is used as a starting material.
^As a method for containing ³⁺ ions, there are, but not limited to, the following two methods.

(1) An Sm ³⁺ ion source is added at an arbitrary stage in the production of a solidified gel (glass precursor) by the sol-gel method.

[0032] (2) a sol solidified by sol-gel method (glass precursor) after production, by immersing the sol solidified body Sm ³⁺ ion source containing solution, immersing the Sm ³⁺ ions in the sol solidified body.

As the Sm ³⁺ ion source, inorganic samarium compounds such as samarium chloride, samarium nitrate, samarium sulfate, samarium oxalate and samarium acetate, and organic samarium compounds such as samarium alkoxide can be used. Method (1) and (2)
In the above, an inorganic samarium compound and an organic samarium compound can be used.

The amount of the Sm ³⁺ ions contained in the aluminosilicate glass precursor is S
The amount is preferably 0.1 to 20% by weight as m ₂ O ₃ . The reason is that if it is less than 0.1 wt%, strong P
It becomes difficult to obtain HB phenomenon, whereas, if it exceeds 20 wt%, (a) occur agglomeration of Sm ²⁺ ions, uniform glass becomes difficult to obtain, also ⁷ F- ⁵ D transition Sm ²⁺ ions (B) crystallization is likely to occur during heating, making it difficult to obtain a transparent glass. The amount of Sm ³⁺ ions is particularly preferably 0.5 to 10% by weight as Sm ₂ O ₃ .

In the present invention, an essential step is to heat-treat the above-mentioned Sm ³⁺ ion-containing aluminosilicate glass precursor as a starting material in a reducing atmosphere.

As the reducing atmosphere, a reducing gas atmosphere such as hydrogen or a reducing gas such as hydrogen and nitrogen, helium,
A mixed gas atmosphere with an inert gas such as argon is used.

By subjecting the Sm ³⁺ ion-containing aluminosilicate glass precursor to a heat treatment in the reducing atmosphere, the glass precursor is vitrified, and the Sm ³⁺ ions are reduced to Sm ²⁺ ions. Aluminosilicate glass containing Sm ²⁺ ions is obtained.

This heat treatment is preferably performed at a temperature of 400 to 1200 ° C. The reason is as follows.

When the heat treatment is carried out at a temperature lower than 400 ° C., (i) water and organic substances are not sufficiently removed, and vitrification becomes incomplete because they remain, and (ii) Sm ³⁺ ions (in the gel) The Sm element is present as Sm ³⁺ ions) is not sufficiently reduced to Sm ²⁺ ions, so that it becomes difficult to produce the glass intended for the present invention.

On the other hand, when heat treatment is performed at a temperature exceeding 1200 ° C., crystallization of the glass matrix occurs, and the glass tends to be opaque.

The ratio of Sm ²⁺ ions in the glass obtained by the above method depends on the heating temperature, time and gas flow during vitrification. That is, by increasing the temperature and lengthening the time, the proportion of Sm ²⁺ ions present can be increased. The same effect can be obtained even if the amount of the atmosphere gas is increased.

A reducing gas such as H ₂ is necessary for the reduction reaction of Sm ³⁺ ions. As the flow rate is increased, the conversion to Sm ²⁺ ions is completed at a lower temperature in a shorter time.

However, if the reducing gas is used at a flow rate (depending on the furnace volume and the amount of glass to be heat-treated),
Oxidation of the organic matter remaining in the gel that becomes the glass matrix is prevented, so that finally free carbon remains in the glass, making it difficult to obtain transparent glass.

Therefore, in order to produce a transparent glass containing Sm ²⁺ ions in a short time, the solidified gel is heated in an oxidizing atmosphere (including air) in advance so that no residual carbon remains. And then heat-treated in a reducing gas. The pre-heat treatment in an oxidizing atmosphere is 400 to 1
It is desirable to carry out at a temperature of 000 ° C.

When the pre-heat treatment temperature is lower than 400 ° C., no decomposition or volatilization occurs even if organic substances remain. Also, at temperatures higher than 1000 ° C., the gel solidified porous pore volume becomes extremely small by sintering, or for non-Anaka, be heat-treated in the subsequent reduction in gas Sm ³⁺
The ions cannot be changed to Sm ²⁺ ions.

According to the present invention, the Sm ²⁺ ion-containing aluminosilicate glass obtained by subjecting the Sm ³⁺ ion-containing aluminosilicate glass precursor to a heat treatment in a reducing atmosphere has SiO ₂ containing Al ₂ O ₃ . Thus, (i) excellent weather resistance (chemical durability) among silicate glasses, (ii) excellent stability of Sm ²⁺ ions generated by reduction of Sm ³⁺ ions, and f− It has the advantage that the f-transition efficiency can be improved and a strong PHB phenomenon can be expressed with good reproducibility, and it is preferably used in the field of optical information such as PHB materials.

[0047]

The present invention will be further described with reference to the following examples.

Example 1 Tetraethoxysilane (Si
(OC ₂ H ₅ ) ₄ ) 149.0 g was added to 0.15 M hydrochloric acid (H
Cl) aqueous solution (12.9 g) and ethanol (C ₂ H ₅ OH)
It was added dropwise to the mixed solution with 33.0 g while stirring. After adding all the Si (OC ₂ H ₅ ) ₄ , the mixture was further stirred for 1 hour to obtain a partially hydrolyzed liquid of Si (OC ₂ H ₅ ) ₄ .
Aluminum tributoxide (A
1 (OC ₄ H ₉ ) ₃ ) was added and heated at 60 ° C. for 1 hour with stirring. Then, samarium chloride 6
Tetrahydrate and _{(SmCl 3 · 6H 2 O)} 5.2g C 2 H 5 OH
The solution dissolved in 25.0 g was added to the above solution, and 1
Stirring was continued for hours. 33.0 g of C ₂ H ₅ OH and 0.1
After adding a mixture with 51.6 g of 5M HCl aqueous solution,
The mixture was stirred for 1 hour, transferred to a plastic container such as polypropylene or polymethylpentene, and left indoors. Further, as the hydrolysis progressed, it gelled and dried, whereby excess water and organic solvent were volatilized to obtain a solidified gel.

The solidified gel was heated from room temperature to 800
After heating to 50 ° C. at a rate of 50 ° C./hr and holding at that temperature for 2 hours for pre-heat treatment, the electric furnace was turned off and cooled to room temperature to obtain a glass body.

The charged composition of this glass body was aluminosilicate glass (10 Al) containing 5.0 wt% of Sm ₂ O _3.
2 O ₃ · 90 SiO ₂ mol%). S in glass
m exists in a trivalent state, and the color of the glass is colorless and transparent.

This glass was placed in an electric annular furnace, and a mixed gas of 20% hydrogen (H ₂ ) / 80% nitrogen (N ₂ ) was added at 25 ml / mi.
By raising the temperature to 700 ° C. at 150 ° C./hr while flowing at n, and maintaining the temperature for 2 hours, Sm ³⁺ was reduced to Sm ²⁺ to produce a transparent Sm ²⁺ ion-containing glass.

The discrimination between Sm ³⁺ and Sm ²⁺ can be made from the emission spectrum of glass. That is, in the state of Sm ³⁺ , a spectrum having emission peaks at 562, 596 and 645 nm is given, and in the state of Sm ²⁺ , the spectrum has 68
The emission peaks are given at 3,700 and 725 nm, and these emission peaks do not overlap each other.

The spectrum of the glass preheat-treated by heating at 800 ° C. in the air as described above has a spectrum as shown in FIG.
whereas was spectra m ³⁺ only, the spectrum of the glass after heating in a reducing gas atmosphere as shown in FIG. 2, the light emitting from the Sm ³⁺ was not observed at all, Sm ²⁺ only The spectrum had changed.

As described above, the glass obtained after the reduction treatment is colorless and transparent, and it can be seen that all Sm in the glass exists in the state of Sm ²⁺ .

After irradiating the glass with a laser having a wavelength of 685 nm, the excitation spectrum for emission at 725 nm was measured in the range of 670 to 700 nm.
In the excitation spectrum having a peak at nm, a depression occurred at 685 nm, and the PHB phenomenon was confirmed.

The durability was evaluated as follows. That is, the aluminosilicate glass of Example 1 and the fluoride glass and the borate glass of the comparative sample were immersed in pure water at 50 ° C., respectively. After 48 hours, when the glass was taken out and examined, the fluoride glass and the borate glass were melted and the surface was altered, whereas the aluminosilicate glass of Example 1 was not altered at all, and the durability was high. It became clear that it was excellent.

Examples 2 to 8 Glasses as shown in Table 1 were prepared in the same manner as in Example 1 except that the content of Sm, the composition of the glass and / or the heating conditions were changed as shown in Table 1. Was prepared. All of the emission spectra of the obtained glasses only show emission from Sm ²⁺ , and all the glasses contain only Sm ²⁺ . Moreover, the obtained glass was able to confirm the PHB phenomenon as in Example 1. Also, as in Example 1, the durability was excellent.

Comparative Example 1 A gel prepared in the same manner as in Example 1 except that Al (OC ₄ H ₉ ) ₃ was not added was prepared at 800 ° C. in air.
For 2 hours to produce a glass having only SiO ₂ as a matrix. The glass was then heated in a 20% H ₂ /80% N ₂ gas mixture as in Example 1,
This emission spectrum is only from Sm ³⁺ , and Sm ²⁺
No luminescence peak derived from No. was found, and no PHB was confirmed.

[0059]

[Table 1]

[0060]

As described in detail above, according to the present invention, a strong PHB phenomenon due to an improvement in the weather resistance (chemical durability) and an improvement in the efficiency of the ff transition can be exhibited with good reproducibility. A method for making a Sm ²⁺ -containing silicate glass has been provided.

[Brief description of the drawings]

FIG. 1. Aluminosilicate gel in air at 800 ° C.
FIG. 7 is an emission spectrum diagram after heating for a time.

FIG. 2 shows aluminosilicate gel in air at 800 ° C.
After heating for a time, reducing gas (20% H ₂ -80% N ₂ )
FIG. 4 is an emission spectrum diagram of the Sm ²⁺ -containing aluminosilicate glass after being heated at 700 ° C. for 2 hours.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C03C 1/00-14/00 CA (STN) JICST file (JOIS)

Claims (6)

(57) [Claims] 1. A heat treatment of an Sm ³⁺ ion-containing aluminosilicate glass precursor in a reducing atmosphere,
A method for producing Sm ²⁺ ion-containing glass, which comprises vitrifying a glass precursor and reducing Sm ³⁺ ions to Sm ²⁺ ions to obtain Sm ²⁺ ion-containing aluminosilicate glass. 2. The method according to claim 1, wherein the aluminosilicate glass precursor is a solidified gel obtained by a sol-gel method. 3. The Sm ³⁺ ion reacts with S
It exists 0.1-20 weight% as m ₂ O _3, The method of claim 1. 4. The method according to claim 1, wherein the reducing atmosphere is a reducing gas atmosphere or a mixed gas atmosphere of a reducing gas and an inert gas. 5. The method according to claim 1, wherein the heat treatment temperature is 400 to 1200 ° C. 6. The method according to claim 1, wherein prior to the reduction, a pre-heat treatment is performed in an oxidizing atmosphere.