WO2016121655A1 - Glass material and method for manufacturing same - Google Patents

Abstract

Provided is a glass composition which exhibits a greater Faraday effect than before. This glass composition is characterized by comprising, in mol%, over 48% (excluding 48%) of Tb₂O₃.

Description

Glass material and manufacturing method thereof

The present invention relates to a glass material suitable for a magneto-optical element constituting a magnetic device such as an optical isolator, an optical circulator, and a magnetic sensor, and a manufacturing method thereof.

It is known that a glass material containing terbium oxide, which is a paramagnetic compound, exhibits a Faraday effect which is one of magneto-optical effects. The Faraday effect is an effect of rotating the polarization plane of linearly polarized light passing through a material placed in a magnetic field. Such effects are used in optical isolators, magnetic field sensors, and the like.

The optical rotation (rotation angle of the polarization plane) θ due to the Faraday effect is expressed by the following equation, where H is the strength of the magnetic field and L is the length of the substance through which the polarized light passes. In the formula, V is a constant depending on the type of substance, and is called Verde's constant. The Verde constant is a positive value for a diamagnetic material and a negative value for a paramagnetic material. The greater the absolute value of the Verde constant, the greater the absolute value of the optical rotation, resulting in a large Faraday effect.

Θ = VHL

Conventionally, as a glass material exhibiting the Faraday effect, SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —Tb ₂ O ₃ glass material (see Patent Document 1), P ₂ O ₅ —B ₂ O ₃ —Tb ₂ An O ₃ glass material (see Patent Document 2), a P ₂ O ₅ —TbF ₃ —RF ₂ (R is an alkaline earth metal) glass material (see Patent Document 3), or the like is known.

Japanese Patent Publication No. 51-46524 Japanese Patent Publication No.52-32881 Japanese Patent Publication No. 55-42942

Although the above glass materials show a certain Faraday effect, in recent years, since the miniaturization of magnetic devices has been further advanced, further improvement of the Faraday effect is required so that even a small member can exhibit a sufficient optical rotation. .

In view of the above, an object of the present invention is to provide a glass material that exhibits a Faraday effect greater than that of the conventional art.

The glass material of the present invention is characterized by containing 48% or more (but not including 48%) of Tb ₂ O ₃ in mol%. The glass material of the present invention has a large Verde constant due to containing a large amount of Tb ₂ O ₃ as described above. As a result, the Faraday effect which is larger than the conventional one is shown. As described above, glass materials containing a large amount of Tb ₂ O ₃ are generally difficult to crow. However, according to the containerless floating method described later, it is possible to easily vitrify even such a composition that is difficult to vitrify.

In the glass material of the present invention, the content of Tb ₂ O ₃ is preferably 80% or less in terms of mol%. If the content of Tb ₂ O ₃ is in the above range, vitrification can be performed relatively easily.

The glass material of the present invention further contains, in mol%, SiO ₂ 0-50%, B ₂ O ₃ 0-50%, Al ₂ O ₃ 0-50%, P ₂ O ₅ 0-50%. Is preferred. Since SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ , and P ₂ O ₅ are components constituting a glass skeleton, vitrification can be performed relatively easily by containing these components.

The glass material of the present invention can be used as a magneto-optical element. For example, the glass material of the present invention can be used as a Faraday rotation element which is a kind of magneto-optical element. By using it for the above application, the effects of the present invention can be enjoyed.

The method for producing a glass material according to the present invention is a method for producing the above glass material, and after the glass material lump is suspended and held, the glass material lump is heated and melted to obtain a molten glass. And a step of cooling the molten glass.

Generally, a glass material is produced by melting a raw material in a melting container such as a crucible and cooling (melting method). However, the glass material of the present invention has a composition containing a large amount of Tb ₂ O ₃ that does not basically constitute a glass skeleton as described above, and is a material that is difficult to vitrify. There is a problem that crystallization proceeds from the contact interface with the substrate.

Even if the composition is difficult to vitrify, it can be vitrified by eliminating contact at the interface with the melting vessel. As such a method, a containerless floating method in which a raw material is melted and cooled in a suspended state is known. When this method is used, since the molten glass hardly comes into contact with the melting vessel, crystallization starting from the interface with the melting vessel can be prevented, and vitrification becomes possible.

According to the present invention, it is possible to provide a glass material that exhibits a Faraday effect that is greater than the conventional one.

It is typical sectional drawing which shows one Embodiment of the apparatus for manufacturing the glass material of this invention.

The glass material of the present invention contains 48% or more (but not 48%) of Tb ₂ O ₃ in mol%, preferably 49% or more, particularly preferably 50% or more. When the content of Tb ₂ O ₃ is too small, the absolute value of the Verdet constant is reduced, a sufficient Faraday effect is difficult to obtain. On the other hand, if the content of Tb ₂ O ₃ is too large, vitrification tends to be difficult, and therefore it is preferably 80% or less, 75% or less, and particularly preferably 70% or less.

In addition, although the content of trivalent oxide is prescribed | regulated about Tb, about the oxide other than trivalent, it is preferable that content when converted into a trivalent oxide is in the said range. .

The magnetic moment that causes the Verde constant for Tb is greater for Tb ³⁺ than for Tb ⁴⁺ . Therefore, the larger the ratio of Tb ^{3+ in} the glass material, the greater the Faraday effect, which is preferable. Specifically, the ratio of Tb ^{3+ in} the total Tb is preferably 50% or more, 60% or more, 70% or more, 80% or more, and particularly 90% or more in mol%.

In addition to Tb ₂ O ₃ , the glass material of the present invention can contain various components shown below. In the following description regarding the content of each component, “%” means “mol%” unless otherwise specified.

SiO ₂ , B ₂ O ₃ and P ₂ O ₅ are components that become a glass skeleton and widen the vitrification range. However, since these components do not contribute to the improvement of the Verde constant, if the content is too large, it is difficult to obtain a sufficient Faraday effect. Accordingly, the contents of SiO ₂ , B ₂ O ₃ and P ₂ O ₅ are preferably 0 to 50%, 1 to 45%, particularly 2 to 40%, respectively. The total amount of SiO ₂ and B ₂ O ₃ is preferably 0 to 52%, 15 to 51%, particularly 20 to 50%. The total amount of B ₂ O ₃ and P ₂ O ₅ is preferably 0 to 52%, 15 to 51%, particularly preferably 20 to 50%. The total amount of SiO ₂ , B ₂ O ₃ and P ₂ O ₅ is preferably 0 to 52%, 15 to 51%, particularly preferably 20 to 50%.

Al ₂ O ₃ is a component that forms a glass skeleton as an intermediate oxide and widens the vitrification range. However, since Al ₂ O ₃ does not contribute to the improvement of the Verde constant, if the content is too large, it becomes difficult to obtain a sufficient Faraday effect. Therefore, the content of Al ₂ O ₃ is preferably 0 to 50%, 0.1 to 40%, 1 to 30%, 1 to 20%, particularly 1 to 10%.

La ₂ O ₃ , Gd ₂ O ₃ , Yb ₂ O ₃ , and Y ₂ O ₃ have the effect of stabilizing the glass, but if the content is too large, it becomes difficult to vitrify. Therefore, the contents of La ₂ O ₃ , Gd ₂ O ₃ , Yb ₂ O ₃ and Y ₂ O ₃ are each preferably 10% or less, particularly preferably 5% or less.

Dy ₂ O ₃ , Eu ₂ O ₃ , and Ce ₂ O ₃ stabilize the glass and contribute to the improvement of the Verde constant. However, when the content is too large, it becomes difficult to vitrify. Therefore, the contents of Dy ₂ O ₃ , Eu ₂ O ₃ and Ce ₂ O ₃ are each preferably 15% or less, particularly preferably 10% or less. In addition, about Dy, Eu, and Ce, the content of the trivalent oxide is specified, but for oxides other than trivalent (for example, CeO ₂ etc.), the content when converted to the trivalent oxide The amount is preferably within the above range.

MgO, CaO, SrO and BaO have the effect of increasing the stability and chemical durability of the glass. However, since it does not contribute to the improvement of the Verde constant, if the content is too large, it becomes difficult to obtain a sufficient Faraday effect. Accordingly, the content of these components is preferably 0 to 10%, particularly 0 to 5%.

Ga ₂ O ₃ has the effect of increasing the glass forming ability and expanding the vitrification range. However, when there is too much the content, it will become easy to devitrify. Further, since the Ga ₂ O ₃ it does not contribute to the improvement of the Verdet constant, when the content is too large, a sufficient Faraday effect difficult to obtain. Therefore, the Ga ₂ O ₃ content is preferably 0 to 6%, particularly preferably 0 to 5%.

Fluorine has the effect of increasing the glass forming ability and expanding the vitrification range. However, if the content is too large, the composition volatilizes during melting and the composition may change, or the stability of the glass may be affected. Therefore, the fluorine content (F ₂ conversion) is preferably 0 to 10%, more preferably 0 to 7%, and still more preferably 0 to 5%.

Sb ₂ O ₃ can be added as a reducing agent. However, the content of Sb ₂ O ₃ is preferably 0.1% or less in order to avoid coloring or in consideration of environmental load.

The glass material of the present invention preferably has a light transmission loss as small as possible particularly when used as a magneto-optical element such as an isolator. Therefore, the light transmittance of the glass material of the present invention is preferably 50% or more, 60%, particularly 70% or more at a wavelength of 633 nm.

The glass material of the present invention can be produced by, for example, a containerless floating method. FIG. 1 is a schematic cross-sectional view showing an example of a manufacturing apparatus for producing a glass material by a containerless floating method. Hereinafter, the manufacturing method of the glass material of this invention is demonstrated, referring FIG.

The glass material manufacturing apparatus 1 has a mold 10. The mold 10 also serves as a melting container. The molding die 10 has a molding surface 10a and a plurality of gas ejection holes 10b opened in the molding surface 10a. The gas ejection hole 10b is connected to a gas supply mechanism 11 such as a gas cylinder. Gas is supplied from the gas supply mechanism 11 to the molding surface 10a via the gas ejection hole 10b. The type of gas is not particularly limited, and may be, for example, air or oxygen, or a reducing gas containing nitrogen gas, argon gas, helium gas, carbon monoxide gas, carbon dioxide gas, or hydrogen. Good.

When manufacturing a glass material using the manufacturing apparatus 1, the glass raw material lump 12 is first arrange | positioned on the molding surface 10a. As the glass raw material block 12, for example, a raw material powder integrated by press molding or the like, a sintered body obtained by integrating raw material powder by press molding or the like, and a composition equivalent to the target glass composition are used. For example, an aggregate of crystals.

Next, the glass raw material block 12 is floated on the molding surface 10a by ejecting gas from the gas ejection holes 10b. That is, the glass raw material block 12 is held in a state where it is not in contact with the molding surface 10a. In this state, the glass material block 12 is irradiated with laser light from the laser light irradiation device 13. Thereby, the glass raw material lump 12 is heated and melted to be vitrified to obtain molten glass. Thereafter, the glass material can be obtained by cooling the molten glass. In the step of heating and melting the glass raw material lump 12 and the step of cooling until the temperature of the molten glass and further the glass material is at least the softening point or less, at least gas ejection is continued, and the glass raw material lump 12, molten glass, Furthermore, it is preferable to suppress contact between the glass material and the molding surface 10a. In addition, you may float the glass raw material lump 12 on the molding surface 10a using the magnetic force which generate | occur | produces by applying a magnetic field. In addition to the method of irradiating laser light, the method of heating and melting may be radiant heating.

Hereinafter, the present invention will be described based on examples, but the present invention is not limited to these examples.

Table 1 shows examples and comparative examples of the present invention.

Each sample was prepared as follows. First, raw materials prepared so as to have the glass composition shown in the table were press-molded, and sintered at 1100 to 1400 ° C. for 12 hours to produce a glass raw material lump.

Next, the glass raw material lump was roughly pulverized in a mortar to obtain small pieces of 0.05 to 0.5 g. A glass material (about 1 to 8 mm in diameter) was produced by the containerless floating method using the apparatus according to FIG. A 100 W CO ₂ laser oscillator was used as the heat source. In addition, nitrogen gas was used as a gas for floating the raw material lump, and was supplied at a flow rate of 1 to 30 L / min.

The Verde constant of the obtained glass material was measured using a Kerr effect measuring device (manufactured by JASCO Corporation, product number: K-250). Specifically, the obtained glass material was polished to a thickness of about 1 mm, the Faraday rotation angle at a wavelength of 400 to 850 nm was measured in a magnetic field of 15 kOe, and the Verde constant at wavelengths of 633 nm and 850 nm was calculated. . The wavelength sweep rate was 6 nm / min. The results are shown in Table 1.

As is apparent from Table 1, the glass materials of Examples 1 to 7 exhibited Verde constants of −0.69 to −1.04 at a wavelength of 633 nm and −0.34 to −0.52 at a wavelength of 850 nm. On the other hand, the Verde constant of the glass material of Comparative Example 1 was −0.37 at a wavelength of 633 nm and −0.18 at a wavelength of 850 nm, and the absolute value was small.

The glass material of the present invention is suitable as a magneto-optical element constituting a magnetic device such as an optical isolator, an optical circulator, or a magnetic sensor.

1: Glass material manufacturing apparatus 10: Mold 10a: Molding surface 10b: Gas ejection hole 11: Gas supply mechanism 12: Glass raw material block 13: Laser beam irradiation apparatus

Claims (6)

1. A glass material characterized by containing, in mol%, 48% or more (but not including 48%) of Tb ₂ O ₃ .
2. The glass material according to claim 1, wherein the content of Tb ₂ O ₃ is 80% or less in terms of mol%.
3. Furthermore, it contains SiO ₂ 0 to 50%, B ₂ O ₃ 0 to 50%, Al ₂ O ₃ 0 to 50%, and P ₂ O ₅ 0 to 50% in mol%. Or the glass material of 2.
4. The glass material according to any one of claims 1 to 3, wherein the glass material is used as a magneto-optical element.
5. The glass material according to claim 4, wherein the glass material is used as a Faraday rotation element.
6. A method for producing the glass material according to any one of claims 1 to 5, wherein the glass raw material lump is heated and melted in a state where the glass raw material lump is suspended and held to obtain a molten glass. After that, the manufacturing method of the glass material characterized by including the process of cooling the said molten glass.

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