JP6686386B2 - Glass material and manufacturing method thereof - Google Patents

Description

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

  It is known that a Faraday effect is exhibited by applying a magnetic field to a magnetic material. The Faraday effect is an effect of rotating the plane of polarization of linearly polarized light passing through a material placed in a magnetic field. Such effects are used in optical isolators and magnetic field sensors.

  The optical rotation (rotation angle of the plane of polarization) θ due to the Faraday effect is represented by the following formula, 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 that depends on the type of substance and is called Verdet constant. The Verdet constant has a positive value for diamagnetic materials and a negative value for paramagnetic materials. The larger the absolute value of the Verdet constant, the larger the absolute value of the optical rotation, resulting in a large Faraday effect.

    θ = VHL

Conventionally, as a glass material showing the Faraday _{effect, SiO 2 -B 2 O 3 -Al} 2 O 3 -Tb 2 O 3 based glass material showing a paramagnetic (see Patent Document _{1), P 2 O 5 -B} 2 O _{A 3-} Tb ₂ O ₃ -based glass material (see Patent Document 2) or a P ₂ O ₅ -TbF ₃ -RF ₂ (R is an alkaline earth metal) -based glass material (see Patent Document 3) and the like are known. ing. A PbO—SiO ₂ glass material is known as a glass material exhibiting diamagnetism (see Non-Patent Document 1).

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

Properties of Glass, Volume 1, (1954), p.545

  The paramagnetic glass material containing terbium as described above has a problem that the Faraday rotation angle fluctuates because the magnetic susceptibility changes with temperature. On the other hand, it is known that the magnetic susceptibility of a diamagnetic glass material has little temperature dependence. Therefore, by using the Faraday rotation glass made of a diamagnetic glass material, it is possible to provide a magneto-optical element in which the Faraday rotation angle changes little with temperature changes.

  However, the conventional diamagnetic glass material has a problem that the absolute value of the Verdet constant is smaller than that of the paramagnetic glass material. In recent years, as magnetic devices have been downsized, further improvement of the Faraday effect is required so that a small member can exhibit sufficient optical rotation.

  In view of the above, it is an object of the present invention to provide a diamagnetic glass material that exhibits a faraday effect greater than conventional ones.

The glass material of the present invention is characterized by containing 73% or more of Yb ₂ O ₃ in mass%.
As described above, the glass material of the present invention has a large Verdet constant due to the large content of Yb ₂ O ₃ and exhibits diamagnetism. As a result, it exhibits a faraday effect larger than that of the conventional diamagnetic glass material. Further, since Yb ₂ O ₃ has almost no light absorption in the wavelength range of 300 to 900 nm, it has a feature that it tends to exhibit a high transmittance even if it is contained in a large amount as described above. Note that glass materials containing a large amount of Yb ₂ O ₃ as described above are generally difficult to vitrify. However, according to the below-mentioned containerless floating method, it becomes possible to easily vitrify such a composition that is difficult to vitrify.

Glass material of the present invention further contains, by _{mass%, B 2 O 3 0~27%} , P 2 O 5 0~27%, SiO 2 0~27%, by containing _Al 2 O 3 _0~27% Is preferred. Since _{B 2 O 3, P 2 O} 5, SiO 2, Al 2 O 3 is a component constituting the glass network, by containing these components, it can be relatively easily perform vitrification.

The glass material of the present invention preferably contains B ₂ O ₃ + P ₂ O ₅ + SiO ₂ 0 to 27% by mass%. In addition, in this specification, "○ + ○ + ..." means the total amount of each applicable component.

  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. The effect of the present invention can be enjoyed by using it for the above purposes.

  The method for producing a glass material of the present invention is a method for producing the above glass material, in a state where the glass raw material lump is suspended and held, and after melting the glass raw material lump by heating 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 vessel such as a crucible and cooling it (melting method). However, the glass material of the present invention basically has a composition containing a large amount of Yb ₂ O ₃ that does not form 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

  Even if the composition is difficult to vitrify, vitrification is possible 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, the molten glass hardly contacts the melting vessel, so that 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 diamagnetic glass material exhibiting a faraday effect larger than ever before.

It is a typical sectional view showing one embodiment of the device for manufacturing the glass material of the present invention.

The glass material of the present invention is characterized by containing 73% or more of Yb ₂ O ₃ by mass%. If the content of Yb ₂ O ₃ is too small, the absolute value of the Verdet constant becomes small, and it becomes difficult to obtain a sufficient Faraday effect. The content of Yb ₂ O ₃ is preferably 75% or more, particularly preferably 77% or more. On the other hand, if the content of Yb ₂ O ₃ is too large, vitrification tends to be difficult, so 95% or less, 94% or less, and particularly 92% or less is preferable.

In addition to Yb 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 “mass%” unless otherwise specified.

B ₂ O ₃ is a component that forms the main glass skeleton and expands the vitrification range. However, since B ₂ O ₃ does not contribute to the improvement of the Verdet constant, if the content is too large, it becomes difficult to obtain a sufficient Faraday effect. Therefore, the content of B ₂ O ₃ is preferably 0 to 27%, 1 to 25%, and particularly preferably 2 to 20%.

P ₂ O ₅ is a component that forms a glass skeleton and expands the vitrification range. However, since P ₂ O ₅ does not contribute to the Verdet constant, if the content is too large, it becomes difficult to obtain a sufficient Faraday effect. Therefore, the content of P ₂ O ₅ is preferably 0 to 27%, 0 to 25%, 0 to 20%, 0 to 10%, and particularly 0 to 10% (excluding 0%).

Al ₂ O ₃ is a component that forms a glass skeleton as an intermediate oxide and expands the vitrification range. However, since Al ₂ O ₃ does not contribute to the improvement of the Verdet 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 27%, 0 to 25%, 0 to 20%, 0 to 10%, and particularly 0 to 10% (excluding 0%).

SiO ₂ is a component that forms a glass skeleton and expands the vitrification range. However, since SiO ₂ does not contribute to the Verdet constant, if the content is too large, it becomes difficult to obtain a sufficient Faraday effect. Therefore, the content of SiO ₂ is 0 to 27%, 0 to 27% (excluding 27%), 0 to 25%, 0 to 20%, 0 to 10%, and particularly 0 to 10% (including 0). No)) is preferred.

The content of SiO ₂ + B ₂ O ₃ is preferably 0 to 27%, 1 to 25%, and particularly 2 to 20%. The content of B ₂ O ₃ + P ₂ O ₅ is preferably 0 to 27%, 1 to 25%, and particularly 2 to 20%. The content of SiO ₂ + B ₂ O ₃ + P ₂ O ₅ is preferably 0 to 27%, 1 to 25%, and particularly 2 to 20%.

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

Y ₂ O ₃ and La ₂ O ₃ have the effect of enhancing the stability of vitrification, but if the content thereof is too large, vitrification becomes rather difficult. Therefore, the content of each of these components is preferably 0 to 10%, particularly preferably 0 to 5%.

Ga ₂ O ₃ has the effect of enhancing the glass forming ability and expanding the vitrification range. However, if its content is too large, devitrification tends to occur. Further, since Ga ₂ O ₃ does not contribute to the improvement of the Verdet constant, if the content is too large, it becomes difficult to obtain a sufficient Faraday effect. Therefore, the content of Ga ₂ O ₃ is preferably 0 to 6%, particularly 0 to 5%.

Fluorine has the effect of enhancing the glass forming ability and expanding the vitrification range. However, if the content is too large, it may volatilize during melting to change the composition or affect the vitrification stability. Therefore, the content of fluorine (converted to F ₂ ) is preferably 0 to 10%, 0 to 7%, particularly 0 to 5%.

  Since the glass material of the present invention has the above composition, it has good Verdet constant and visible light transmittance. Specifically, the Verdet constant of the glass material of the present invention has a wavelength of 400 nm of 0.25 min / Oe · cm or more, 0.28 min / Oe · cm or more, 0.30 min / Oe · cm or more, and particularly 0.32 min / Oe · cm or more is preferable, and 0.08 min / Oe · cm or more, 0.085 min / Oe · cm or more, 0.090 min / Oe · cm or more, 0.095 min / Oe · cm or more, especially at a wavelength of 600 nm. It is preferably 0.100 min / Oe · cm or more. Further, the visible light transmittance of the glass material of the present invention is preferably 50% or more, particularly 60% or more at a wavelength of 400 nm, and 60% or more, 70% or more, particularly 80% or more at a wavelength of 600 nm. preferable.

  The glass material of the present invention can be produced, for example, by a containerless floating method. FIG. 1 is a schematic cross-sectional view showing an example of a manufacturing apparatus for manufacturing a glass material by a containerless floating method. Hereinafter, the method for manufacturing a glass material of the present invention will be described with reference to FIG.

  The glass material manufacturing apparatus 1 has a molding die 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 opening 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 holes 10b. The type of gas is not particularly limited, and may be, for example, air or oxygen, or nitrogen gas, argon gas, helium gas, carbon monoxide gas, carbon dioxide gas, or reducing gas containing hydrogen. Good.

  When manufacturing a glass material using the manufacturing apparatus 1, first, the glass raw material block 12 is placed on the molding surface 10a. Examples of the glass raw material ingot 12 include a raw material powder integrated by press molding or the like, a sintered body obtained by integrating the raw material powder by press molding or the like, or a composition equivalent to the target glass composition. Examples thereof include aggregates of crystals.

  Next, the glass raw material lump 12 is floated on the molding surface 10a by ejecting gas from the gas ejection holes 10b. That is, the glass raw material lump 12 is held in a state where it is not in contact with the molding surface 10a. In this state, the laser light irradiation device 13 irradiates the glass raw material block 12 with laser light. Thereby, the glass raw material lump 12 is heated and melted to be vitrified to obtain molten glass. After that, 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 in the step of cooling the molten glass, and further cooling the glass material until the temperature of the glass material becomes at least the softening point or less, at least gas ejection is continued, and the glass raw material lump 12, the molten glass, Furthermore, it is preferable to suppress contact between the glass material and the molding surface 10a. The glass raw material mass 12 may be floated on the molding surface 10a by utilizing the magnetic force generated by applying a magnetic field. The method of heating and melting may be radiation heating, instead of the method of irradiating with laser light.

  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, a raw material prepared to have a glass composition shown in the table was press-molded and sintered at 800 to 1400 ° C. for 12 hours to prepare a glass raw material lump.

Next, the glass raw material lump was roughly crushed in a mortar to give 0.05 to 0.5 g of small pieces. Using a small piece of the obtained glass raw material lump, a glass material (having a diameter of about 1 to 15 mm) was produced by a containerless floating method using an apparatus according to FIG. A 100 W CO ₂ laser oscillator was used as the heat source. Further, O ₂ gas was used as a gas for suspending the raw material block, and was supplied at a flow rate of 1 to 30 L / min.

  The Verdet constant and the transmittance of the obtained glass material were measured as follows.

  The Verdet constant was measured using the rotating analyzer method. Specifically, the obtained glass material was polished to have a thickness of 1 mm, the Faraday rotation angle at a wavelength of 400 to 1100 nm was measured in a magnetic field of 15 kOe, and the Verdet constant was calculated. The wavelength sweep rate was 6 nm / min.

  The light transmittance was measured using a spectrophotometer (UV-3100 manufactured by Shimadzu Corporation). Specifically, the obtained glass material is polished to have a thickness of 1 mm, and the wavelengths of 400 nm, 500 nm, 600 nm and 800 nm are obtained from the light transmittance curve obtained by measuring the transmittance at wavelengths of 300 to 1400 nm. The light transmittance was read. The light transmittance is the external transmittance including reflection.

  As is clear from Table 1, the Verdet constants of the glass materials of Examples 1 to 5 were 0.326 to 0.494 min / Oe · cm at 400 nm and 0.105 to 0.159 min / Oe · cm at 600 nm. It is understood that the glass materials of Examples 1 to 5 are diamagnetic because the Verdet constant has a positive value. In addition, the light transmittances were all over 60% at a wavelength of 400 nm, and over 80% at a wavelength of 500 to 800 nm, showing good visible light transmittance.

  On the other hand, the Verdet constant of the glass material of Comparative Example 1 was as small as 0.241 min / Oe · cm at 400 nm and 0.079 min / Oe · cm at 600 nm.

  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 and 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 mass 13: Laser light irradiation device

Claims (6)

A glass material containing 73% or more of Yb ₂ O ₃ and 0 to 27% (not including 0%) of Al ₂ O _{3 in} mass% . The glass material according to claim 1, further comprising B ₂ O _{3 0 to} 27%, P ₂ O _{5 0 to} 27%, and SiO ₂ 0 to 27 % in mass % . By _{mass%, B 2 O 3 + P} 2 O 5 + glass material according to claim 1 or 2, characterized in that it contains SiO 2 0 to 27%.   The glass material according to claim 1, which is used as a magneto-optical element.   The glass material according to claim 4, which is used as a Faraday rotation element.   It is a method for manufacturing the glass material as described in any one of Claims 1-5, Comprising: In the state which floated and hold | maintained the glass raw material block, the said glass raw material block was heat-melted and molten glass was obtained. And then cooling the molten glass.