Glass material manufacturing method

Abstract

The present invention provides a method for manufacturing glass materials with high light transmittance. [Solution] A method for manufacturing a glass material, wherein the glass material is a paramagnetic glass material, and the method comprises a vacuum sealing step of vacuum sealing a glass raw material in a container, and a melting step of melting the glass raw material.

Description

[Technical Field]

[0001] This invention relates to a method for manufacturing glass materials. [Background technology]

[0002] Paramagnetic glass materials are known to exhibit the Faraday effect, a magneto-optical effect. The Faraday effect is the rotation of linearly polarized light passing through a material placed in a magnetic field. Magneto-optical elements that utilize this effect (e.g., Faraday rotators) are used in magneto-optical devices such as optical isolators.

[0003] Examples of paramagnetic glass materials include the SiO2-B2O3-Al2O3-Tb2O3 system (Patent Document 1) and the P2O5-B2O3-Tb2O3 system (Patent Document 2). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Special Publication No. 51-46524 [Patent Document 2] Special Publication No. 52-32881 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] In recent years, the laser light irradiated onto magneto-optical devices has been increasing in power. As the laser light output increases, the temperature of the magneto-optical element rises, making it more susceptible to beam diameter changes due to the thermal lensing effect. Therefore, from the perspective of reducing the thermal lensing effect, there is a need to improve the light transmittance of the glass material used in magneto-optical elements.

[0006] In view of the above, the present invention aims to provide a method for manufacturing a glass material with high light transmittance. [Means for solving the problem]

[0007] A method for manufacturing glass materials that solves the above problems will be described below.

[0008] The method for manufacturing a glass material according to Embodiment 1 is a method for manufacturing a glass material, wherein the glass material is a paramagnetic glass material, and comprises a vacuum sealing step of vacuum sealing the glass raw material into a container, and a melting step of melting the glass raw material.

[0009] In the method for manufacturing the glass material of Embodiment 2, it is preferable that the glass raw material contains a reducing agent in Embodiment 1.

[0010] In the manufacturing method of the glass material according to Embodiment 3, it is preferable that the melting temperature is 1200°C to 1450°C in Embodiment 1 or Embodiment 2.

[0011] In the method for manufacturing the glass material of Embodiment 4, it is preferable that the paramagnetic glass material is a Tb2O3-based glass material in any one embodiment from Embodiments 1 to 3.

[0012] In the method for manufacturing the glass material of Embodiment 5, it is preferable that in any one embodiment from Embodiments 1 to 4, the Tb2O3-based glass material contains, in mol% terms, 10% to 90% Tb2O3 and 51% to 89% B2O3 + Al2O3 + SiO2 + P2O.

[0013] In the method for manufacturing the glass material of Embodiment 6, it is preferable that the container is a quartz glass container in any one embodiment from Embodiments 1 to 5.

[0014] In the method for manufacturing the glass material of Embodiment 7, it is preferable that the reducing agent is metallic aluminum in any one embodiment from Embodiments 1 to 6.

[0015] In the method for manufacturing the glass material of Embodiment 8, in any one embodiment from Embodiments 1 to 7, it is preferable that the glass material has a thickness of 1 mm and a light transmittance of 70% or more at a wavelength of 532 nm. [Effects of the Invention]

[0016] According to the present invention, a method for manufacturing a glass material with high light transmittance can be provided.

Embodiments for Carrying Out the Invention

[0017] Hereinafter, preferred embodiments will be described. However, the following embodiments are merely illustrative, and the present invention is not limited to the following embodiments.

[0018] <Vacuum Encapsulation Step> First, a glass raw material mixed to have a desired glass composition is vacuum-encapsulated in a container. The container is preferably a quartz glass container. In the following description, it is assumed that the container is a quartz glass container. First, the glass raw material is mixed to have a desired glass composition to obtain a raw material batch. Next, after evacuating the quartz glass container while heating it, the raw material batch is put in, and the glass raw material is encapsulated in the quartz glass container using an oxygen burner.

[0019] From the viewpoint of suppressing oxidation of the glass material, the glass raw material preferably contains a reducing agent. The reducing agent is preferably at least one selected from, for example, carbon, wood powder, metallic aluminum, metallic silicon, aluminum fluoride, and ammonium salts. From the viewpoint of suppressing the mixing of impurities into the glass material, metallic silicon or metallic aluminum is preferable, and particularly metallic aluminum is preferable. Also, the reducing agent is preferably used in powder form. Thereby, the reducing agent can be uniformly distributed in the glass raw material.

[0020] The content of the reducing agent is preferably 1 ppm or more, particularly preferably 10 ppm or more, and preferably 1000 ppm or less, 500 ppm or less, particularly preferably 300 ppm or less. If the reducing agent is too much, the molten glass may be excessively reduced, and conversely, the glass material may be colored.

[0021] <Melting Step> Next, the vacuum-sealed glass raw material is melted. Melting the glass raw material under a vacuum atmosphere suppresses changes in the valence of the constituent components, making it easier to suppress the decrease in the light transmittance of the glass material. For example, if the glass material is a Tb2O3-based glass material, Tb 3+ Tb 4+ This suppresses oxidation and prevents a decrease in the light transmittance of the glass material.

[0022] The melting time is preferably 30 minutes or more, and more preferably 1 hour or more. It is also preferable that it be 20 hours or less, 15 hours or less, 10 hours or less, and more preferably 9 hours or less. If the melting time is too short, incomplete dissolution of the glass raw material is likely to occur. If the melting time is too long, the components of the melting container are more likely to dissolve into the molten glass. For example, when melting glass raw materials using a quartz glass container, SiO2 dissolution occurs into the molten glass, making it difficult to obtain a glass material with the desired composition. In addition, components due to dissolution are likely to cause striations.

[0023] The melting temperature is preferably 1200°C or higher, particularly 1300°C or higher, and preferably 1450°C or lower, particularly 1400°C or lower. If the melting temperature is too low, undissolved glass raw materials are likely to occur. If the melting temperature is too high, the components of the molten container are more likely to dissolve into the molten glass. For example, when melting glass raw materials using a quartz glass container, SiO2 dissolution occurs into the molten glass, making it difficult to obtain a glass material with the desired composition. In addition, components dissolved in the glass are likely to cause striations.

[0024] During melting, the molten material may be stirred by shaking or rotating the quartz glass container as needed.

[0025] Finally, the quartz glass container is removed from the melting furnace and rapidly cooled to room temperature to obtain the glass material.

[0026] <Glass composition> The glass material manufacturing method of the present invention can be used for the manufacture of paramagnetic glass materials. When paramagnetic glass materials are oxidized during their manufacture, the valence of their constituent components changes, and their properties (e.g., light transmittance) tend to change. Therefore, by using the manufacturing method of the present invention, oxidation of the paramagnetic glass material can be suppressed, and changes in its properties can be easily suppressed. The paramagnetic glass material is preferably, for example, a Tb2O3-based glass material, a Pr2O3-based glass material, or an EuO-based glass material, and is particularly preferably a Tb2O3-based glass material.

[0027] The Tb2O3-based glass material preferably contains 10% to 90% Tb2O3 and 51% to 89% B2O3 + Al2O3 + SiO2 + P2O in molar percentages. The reasons for specifying the glass composition in this way and the content of each component are explained below. In the following explanation, unless otherwise specified, "%" means "molar percentage".

[0028] Tb2O3 is a component that increases the absolute value of Verde's constant, thereby enhancing the Faraday effect. The Tb2O3 content is preferably 10% to 90%, 10% to 70%, 10% to 50%, 10% to 40%, and especially preferably 20% to 40%. If the Tb2O3 content is too low, the above effect will be difficult to obtain. If the Tb2O3 content is too high, vitrification will be difficult. Note that Tb exists in the glass in trivalent and tetravalent states, but in this invention, all of these are represented as Tb2O3.

[0029] Tb for all Tb 3+ The proportion is preferably 55% or more, 60% or more, 70% or more, 80% or more, and especially 90% or more in mol%. This is because Tb, which is the cause of discoloration of the glass material, is suppressed. 4+ The proportion of Tb decreases, making it easier to suppress the decrease in light transmittance of the glass material. 4+ It has absorption at wavelengths of 300-1100 nm. Tb relative to total Tb 3+If the ratio is too small, the glass material will be colored, the light transmittance in the above wavelength range will decrease, and the glass material will tend to generate heat. This heat generation causes a thermal lens effect, so when the glass material is irradiated with laser light, the beam profile of the laser light is likely to be deformed.

[0030] As described above, in the present invention, the glass raw material is vacuum-sealed in a container to produce a glass material. Therefore, according to the manufacturing method of the present invention, Tb 3+ is less likely to be oxidized to Tb 4+ , and it becomes easier to increase the ratio of Tb 3+ to the total Tb.

[0031] The content of B2O3 + Al2O3 + SiO2 + P2O5 (the total amount of B2O3, Al2O3, SiO2, and P2O5) is preferably 1% to 89%, 20% to 80%, 40% to 80%, 50% to 80%, particularly 60% to 80%. If the content of B2O3 + Al2O3 + SiO2 + P2O5 is too small, it becomes difficult to vitrify. If the content of B2O3 + Al2O3 + SiO2 + P2O5 is too large, it becomes difficult to obtain a sufficient Faraday effect.

[0032] B2O3 is a component that expands the vitrification range and stabilizes vitrification. The content of B2O3 is preferably 0% to 89%, 1% to 50%, 5% to 40%, particularly 5% to 30%. If the content of B2O3 is too small, it becomes difficult to vitrify. If the content of B2O3 is too large, it becomes difficult to obtain a sufficient Faraday effect. Also, the thermal stability and the hardness of the glass tend to decrease.

[0033] Al2O3 is a component that forms the glass skeleton and expands the vitrification range. The content of Al2O3 is preferably 0% to 89%, 1% to 50%, 5% to 40%, particularly 5% to 30%. If the content of Al2O3 is too small, it is difficult to obtain the above effects. If the content of Al2O3 is too large, it becomes difficult to obtain a sufficient Faraday effect.

[0034] SiO2 forms the glass skeleton and is a component that expands the vitrification range. The SiO2 content is preferably 0% to 89%, 1% to 50%, 5% to 40%, and especially 5% to 30%. If the SiO2 content is too low, the above effects will be difficult to obtain. If the SiO2 content is too high, it will be difficult to obtain a sufficient Faraday effect.

[0035] P2O5 forms the glass skeleton and is a component that expands the vitrification range. The P2O5 content is preferably 0% to 20%, 0% to less than 10%, 0% to 5%, and especially 0.1% to 5%. If the P2O5 content is too high, it becomes difficult to obtain a sufficient Faraday effect. In addition, thermal stability and hardness tend to decrease.

[0036] In addition to the above components, Tb2O3-based glass materials may also contain the following components.

[0037] La2O3, Gd2O3, Y2O3, and Yb2O3 are components that stabilize vitrification. The preferred content of La2O3, Gd2O3, Y2O3, and Yb2O3 is 10% or less, 7% or less, 5% or less, 4% or less, 2% or less, and especially 1% or less, respectively. If the content of these components is too high, vitrification becomes more difficult.

[0038] Dy2O3, Eu2O3, and Ce2O3 are components that also contribute to improving the Verde constant. The content of Dy2O3, Eu2O3, and Ce2O3 is preferably 1% or less, 0.5% or less, 0.1% or less, and particularly preferably 0.01% or less, respectively. If the content of these components is too high, the light transmittance at wavelengths of 300-1100 nm decreases, and the glass material becomes more prone to overheating. This overheating can cause deformation of the laser beam profile due to the thermal lensing effect. Note that Dy, Eu, and Ce present in the glass exist in trivalent and tetravalent states, but in this invention, all of these are represented as Dy2O3, Eu2O3, and Ce2O3, respectively.

[0039] Pr2O3 is a component that contributes to improving the Verde constant. The Pr2O3 content is preferably 5% or less, 3% or less, less than 1%, and especially 0.5% or less. Too much Pr2O3 content makes vitrification difficult.

[0040] MgO, CaO, SrO, and BaO are components that stabilize vitrification and enhance chemical durability. The preferred content of MgO, CaO, SrO, and BaO is 0% to 10%, particularly 0% to 5%. If the content of these components is too high, it becomes difficult to obtain a sufficient Faraday effect.

[0041] GeO2 is an ingredient that enhances glass-forming ability. The GeO2 content is preferably 0% to 15%, 0% to 10%, 0% to 9%, 0% to 7%, 0% to 5%, and especially preferably 0% to 4%. If the GeO2 content is too high, it becomes difficult to obtain a sufficient Faraday effect.

[0042] Ga2O3 is a component that enhances glass-forming ability and broadens the vitrification range. The Ga2O3 content is preferably 0% to 6%, 0% to 5%, 0% to 4%, and especially 0% to 2%. Too much Ga2O3 can actually lead to devitrification, and it can also make it difficult to obtain a sufficient Faraday effect.

[0043] Fluorine enhances glass-forming ability and broadens the vitrification range. The fluorine content (F2 equivalent) is preferably 0% to 10%, 0% to 7%, 0% to 5%, 0% to 3%, 0% to 2%, and particularly preferably 0% to 1%. If the fluorine content is too high, components may volatilize during melting, potentially negatively impacting vitrification. Furthermore, striations may easily form.

[0044] The glass material preferably contains FeO and Fe2O3 at concentrations of 10 ppm or less, 7 ppm or less, 5 ppm or less, 4 ppm or less, 2 ppm or less, 1 ppm or less, and especially 0.8 ppm or less, respectively. FeO has a peak at a wavelength of around 1200 nm. 2+Due to the broad absorption caused by this, the light transmittance in the 800-1200 nm wavelength range decreases, making the glass material more prone to heating. This heating can cause a thermal lensing effect, which can lead to deformation of the laser beam profile. In addition, Fe2O3 is reduced to FeO during the melting process, and similarly Fe 2+ This may cause broad absorption. Therefore, if the FeO+Fe2O3 content is too high, a thermal lensing effect will occur, making it easier for the laser beam profile to deform. There is no particular lower limit to the FeO+Fe2O3 content, but for example, it is 0.01 ppm or more. Furthermore, the content of FeO and Fe2O3 respectively is preferably 10 ppm or less, 7 ppm or less, 5 ppm or less, 4 ppm or less, 2 ppm or less, 1 ppm or less, and especially 0.8 ppm or less.

[0045] It is preferable that the glass material is substantially free of Sb2O3 and As2O3. The presence of these components makes it easier for air bubbles to remain in the glass material, which tends to reduce its light transmittance. Note that "substantially free" means intentionally excluding these components from the glass raw materials, and does not mean eliminating even impurity levels. Objectively, this refers to a content of less than 1000 ppm of each component.

[0046] The glass material preferably has a light transmittance of 70% or more, 72% or more, 75% or more, and especially 80% or more at a wavelength of 532 nm. Note that the above light transmittance values ​​are for a glass material thickness of 1 mm.

[0047] Thus, in the glass material manufacturing method of the present invention, by sealing the glass raw material of the paramagnetic glass material in a container under vacuum and melting it, it becomes easier to suppress the decrease in the light transmittance of the glass material due to oxidation of the raw material. For example, if the glass material is a Tb2O3-based glass material, Tb 3+ Tb 4+ This suppresses oxidation and prevents a decrease in the light transmittance of the glass material. [Examples]

[0048] The present invention will be described below based on examples, but the present invention is not limited to these examples.

[0049] First, glass raw materials were prepared so that the molar percentages were Tb2O3 25%, SiO2 23%, B2O3 22%, Al2O3 23%, and P2O 57%, and 100 ppm of metallic aluminum was added as a reducing agent. The prepared glass raw materials were placed in a quartz tube, vacuum sealed, and melted at 1400°C for 1 hour. Next, the mixture was transferred to an electric furnace maintained at 700°C for 1 hour, and then cooled to room temperature to obtain the glass material. For the obtained glass material, the light transmittance at a thickness of 1 mm and a wavelength of 532 nm, and the Tb ratio of the total Tb of the glass material were measured. 3+ The proportion was measured.

[0050] Light transmittance was measured using a spectrophotometer (V-670, JASCO Corporation). Specifically, the obtained glass material was polished to a thickness of 1 mm, and the light transmittance at a wavelength of 532 nm was read from the light transmittance curve. Note that the light transmittance is the external transmittance, including reflection.

[0051] Tb for all Tb 3+ The proportion was measured using X-ray absorption fine structure analysis (XAFS). Specifically, the spectrum of the X-ray absorption edge structure region (XANES) was obtained, and the proportion of Tb relative to total Tb was calculated from the shift amount of the peak position of each Tb ion. 3+ The percentage was calculated.

[0052] Tb of the obtained glass material relative to the total Tb 3+ The percentage was 98%. Furthermore, the light transmittance at a thickness of 1 mm and a wavelength of 532 nm was 87.1%. [Industrial applicability]

[0053] Glass materials produced by the manufacturing method of the present invention can be suitably used as magneto-optical elements (e.g., Faraday elements) that constitute magnetic devices such as optical isolators, optical circulators, and magnetic sensors.

Claims

1. A method for manufacturing glass materials, The aforementioned glass material is a paramagnetic glass material. The vacuum sealing process involves vacuum sealing glass raw materials into a container. A method for manufacturing a glass material, comprising a melting step of melting the aforementioned glass raw material.

2. The method for producing a glass material according to claim 1, wherein the glass raw material contains a reducing agent.

3. A method for manufacturing a glass material according to claim 1 or 2, wherein the melting temperature is 1200°C to 1450°C.

4. The paramagnetic glass material is Tb ２ O ３ A method for manufacturing a glass material according to claim 1 or 2, wherein the glass material is a glass-based material.

5. The above-mentioned Tb ２ O ３ -system glass material contains, in mol%, Tb ２ O ３ 10% to 90%, B ２ O ３ + Al ２ O ３ + SiO ２ + P ２ O ５ 1% to 89%, and the method for manufacturing the glass material according to claim 4.

6. The method for manufacturing a glass material according to claim 1 or 2, wherein the container is a quartz glass container.

7. The method for producing a glass material according to claim 2, wherein the reducing agent is metallic aluminum.

8. The method for manufacturing a glass material according to claim 1 or 2, wherein the glass material has a thickness of 1 mm and a light transmittance of 70% or more at a wavelength of 532 nm.