Glass and low-frequency light transmissive material

Abstract

To provide glass that is suitable for use as a low-frequency light transmissive material, and also to provide a low-frequency light transmissive material.SOLUTION: Glass containing, as a glass composition, SiO2+B2O3+Al2O3 in an amount of more than 0 mol% to 99 mol%, SiO2 in an amount of more than 0 mol% to less than 99 mol%, Li2O+Na2O+K2O in an amount of more than 0 mol ppm to 1000 mol ppm, and MgO+CaO+SrO+BaO in an amount of more than 0 mol ppm to 1000 mol ppm, and having an absorption coefficient of 50 cm-1 or less in a frequency range of 0.1 THz to 3 THz.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to glass and low frequency light transmitting materials. [Background technology]

[0002] Low-frequency light is an electromagnetic wave with a frequency (0.1 THz to 10 THz) that is intermediate between that of light and radio waves. Low-frequency light is transparent to various materials and has higher resolution than millimeter waves, so it is expected to be applied in many fields, such as imaging and non-destructive testing.

[0003] As a specific application example, for example, a terahertz wave camera and detection module have been disclosed (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-105622 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-317573 Summary of the Invention [Problem to be solved by the invention]

[0005] As mentioned above, low-frequency light is transparent to various materials. For example, optical elements made of silicon or resin are used in such optical systems (Patent Documents 1 and 2). However, silicon is a crystalline material and has poor moldability, and resin materials have poor weather resistance.

[0006] Glass is an example of a material that has excellent formability and weather resistance. However, glass has not been sufficiently investigated as a low-frequency light transmitting material, and there is room for further study.

[0007] In view of the above, an object of the present invention is to provide a glass and a low-frequency light transmitting material that are suitable as a low-frequency light transmitting material. [Means for solving the problem]

[0008] Various aspects of the low-frequency light transmitting material that solves the above problems will be described.

[0009] The glass of embodiment 1 has a glass composition of SiO2 + B2O3 + Al2O3, more than 0 mol% to 99 mol%, more than 0 mol% to less than 99 mol%, Li2O + Na2O + K2O, more than 0 mol ppm to 1000 mol ppm, and MgO + CaO + SrO + BaO, and has an absorption coefficient of 50 cm at a frequency of 0.1 THz to 3 THz. -1 It is characterized by the following: Here, "SiO2 + B2O3 + Al2O3" refers to the total amount of SiO2, B2O3, and Al2O3. In the following description, unless otherwise specified, low-frequency light refers to electromagnetic waves having a frequency of 0.1 THz to 10 THz, and particularly refers to electromagnetic waves having a frequency of 0.1 THz to 3 THz.

[0010] In the glass of embodiment 2, in embodiment 1, it is preferable that SO3 + SnO2 is contained in an amount of more than 0.5 mol %.

[0011] In the glass of embodiment 3, in embodiment 1 or 2, it is preferable that Fe2O3+Cr2O3+TiO2+ZrO2+MoO3 be contained in an amount of more than 0 to 2000 ppm by mole.

[0012] In the glass of embodiment 4, in any one of embodiments 1 to 3, it is preferable that the glass contains 30 mol % to 80 mol % of B2O and 30 mol % to 80 mol % of Al2O.

[0013] The glass of Aspect 5 preferably contains more than 0 mol % and up to 80 mol % of B2O3 + Al2O3 in any one of Aspects 1 to 4. Here, "B2O3 + Al2O3" refers to the total amount of B2O3 and Al2O3.

[0014] In the glass of embodiment 6, in any one of embodiments 1 to 5, the absorption coefficient at a frequency of 1 THz is 30 cm -1 It is preferable that:

[0015] In the glass of embodiment 7, in any one of embodiments 1 to 6, the absorption coefficient at a frequency of 0.3 THz is 5.0 cm -1 It is preferable that:

[0016] In the glass of embodiment 8, in any one of embodiments 1 to 7, the glass transition temperature (Tg) is preferably 1000° C. or less.

[0017] The glass of the ninth embodiment is preferably used as a low-frequency light transmitting material in any one of the first to eighth embodiments.

[0018] The glass of embodiment 10 is preferably used as an optical element in any one of embodiments 1 to 9.

[0019] The low-frequency light transmitting material of embodiment 11 has a glass composition containing SiO2 + B2O3 + Al2O3, more than 0 mol% to 99 mol%, SiO2, more than 0 mol% to less than 99 mol%, Li2O + Na2O + K2O, more than 0 mol ppm to 1000 mol ppm, and MgO + CaO + SrO + BaO, more than 0 mol ppm to 1000 mol ppm, and has an absorption coefficient of 50 cm at a frequency of 0.1 THz to 3 THz. -1 The glass is characterized in that it contains the following glass: [Effects of the Invention]

[0020] According to the present invention, it is possible to provide glass and low-frequency light transmitting materials that are suitable as low-frequency light transmitting materials. DETAILED DESCRIPTION OF THE INVENTION

[0021] The glass of the present invention has a glass composition of SiO2 + B2O3 + Al2O3, more than 0 mol% to less than 99 mol%, SiO2, more than 0 mol% to less than 99 mol%, Li2O + Na2O + K2O, more than 0 mol ppm to 1000 mol ppm, and MgO + CaO + SrO + BaO, and has an absorption coefficient of 50 cm at a frequency of 0.1 THz to 3 THz. -1 The low-frequency light transmitting material of the present invention is characterized by having a glass composition of SiO2 + B2O3 + Al2O3 from more than 0 mol% to 99 mol%, SiO2 from more than 0 mol% to less than 99 mol%, and Li2O + Na2O + K2O from more than 0 mol ppm to 1000 mol ppm, and an absorption coefficient of 50 cm at a frequency of 0.1 THz to 3 THz. -1 The glass composition is characterized by including the following glass: The reasons for specifying the glass composition as above and the content of each component will be explained below.

[0022] SiO2, B2O3, and Al2O3 are glass framework components that enhance the stability of the glass. The content of SiO2 + B2O3 + Al2O3 is greater than 0 mol% and up to 99 mol%, preferably 1 mol% to 98 mol%, 1 mol% to 97 mol%, 5 mol% to 96 mol%, 10 mol% to 95 mol%, 20 mol% to 94 mol%, 30 mol% to 93 mol%, 40 mol% to 92 mol%, 50 mol% to 91 mol%, and particularly preferably 60 mol% to 90 mol%. If the content of SiO2 + B2O3 + Al2O3 is too low, it becomes difficult to achieve the above-mentioned effects. If the content of SiO2 + B2O3 + Al2O3 is too high, the softening temperature of the glass increases too much, making it prone to poor formability. From the viewpoint of reducing the absorption coefficient particularly in the frequency range of 0.1 THz to 3 THz, the lower limit of the content of SiO2 + B2O3 + Al2O3 is preferably 30 mol% or more, 40 mol% or more, 50 mol% or more, 60 mol% or more, 70 mol% or more, 80 mol% or more, 90 mol% or more, 95 mol% or more, 99 mol% or more, 99.5 mol% or more, or 99.9 mol% or more. When other components are incorporated as optional components, the upper limit of the content of SiO2 + B2O3 + Al2O3 may be less than 100 mol%, 99.9 mol% or less, 99 mol% or less, 98 mol% or less, 95 mol% or less, 90 mol% or less, 85 mol% or less, and particularly 80 mol% or less.

[0023] The preferred ranges of the respective components SiO2, B2O3 and Al2O3 are as follows:

[0024] SiO2 is a component that increases the stability of glass and tends to reduce the absorption coefficient at frequencies from 0.1 THz to 3 THz. The SiO2 content is greater than 0 mol% and less than 99 mol%, preferably 1 mol% to 99 mol%, 5 mol% to 98 mol%, 10 mol% to 96 mol%, 20 mol% to 95 mol%, 30 mol% to 94 mol%, 40 mol% to 93 mol%, 50 mol% to 92 mol%, 60 mol% to 87 mol%, and particularly preferably 70 mol% to 83 mol%. If the SiO2 content is too low, the absorption coefficient at frequencies from 0.1 THz to 3 THz tends to increase. Also, weather resistance tends to decrease. If the SiO2 content is too high, the softening temperature tends to rise significantly, which tends to decrease formability. In particular, from the viewpoint of reducing the absorption coefficient at frequencies of 0.1 THz to 3 THz, the lower limit of the SiO2 content is preferably 60 mol % or more, more preferably 70 mol % or more, 80 mol % or more, 85 mol % or more, and particularly preferably 90 mol % or more.

[0025] B2O3 is a component that improves the meltability and devitrification resistance of glass. The B2O3 content is preferably 0 mol% to 80 mol%, more preferably 1 mol% to 75 mol%, 2 mol% to 70 mol%, 3 mol% to 60 mol%, 5 mol% to 50 mol%, 7 mol% to 40 mol%, 10 mol% to 35 mol%, 15 mol% to 30 mol%, and particularly preferably 15 mol% to 25 mol%. If the B2O3 content is too high, weather resistance is likely to decrease and phase separation is likely to occur during molding. When weather resistance is particularly prioritized, the upper limit of the B2O3 content is preferably 30 mol% or less, more preferably 20 mol% or less, and particularly preferably 10 mol% or less. If the B2O3 content is too low, the glass transition temperature increases and the moldability of the glass is likely to decrease.

[0026] Al2O3 is a component that improves the weather resistance of glass. The Al2O3 content is preferably 0 mol% to 80 mol%, more preferably 0.1 mol% to 75 mol%, 0.5 mol% to 70 mol%, or 0.8 mol% to 60 mol%, and particularly preferably 1 mol% to 50 mol%. If the Al2O3 content is too high, the transmittance of low-frequency light is likely to decrease and meltability is likely to decrease. If meltability is prioritized, the upper limit of the Al2O3 content is preferably 40 mol% or less, and more preferably 30 mol% or less, 20 mol% or less, 10 mol% or less, 5 mol% or less, 3 mol% or less, and particularly preferably 2 mol% or less.

[0027] The inclusion of B2O3 and / or Al2O3 can effectively improve the formability of glass. Therefore, the B2O3 + Al2O3 content (total amount of B2O3 and Al2O3) is preferably greater than 0 mol% to 80 mol%, more preferably greater than 0 mol% to 70 mol%, greater than 0 mol% to 60 mol%, greater than 0 mol% to 50 mol%, greater than 0 mol% to 40 mol%, 1 mol% to 40 mol%, 3 mol% to 40 mol%, 5 mol% to 40 mol%, 10 mol% to 40 mol%, 10 mol% to 30 mol%, 15 mol% to 25 mol%, and particularly preferably 19 mol% to 23 mol%. If the B2O3 + Al2O3 content is too low, the formability of the glass tends to decrease. If the B2O3 + Al2O3 content is too high, the absorption coefficient at frequencies from 0.1 THz to 3 THz tends to increase.

[0028] From the viewpoint of reducing the thermal expansion coefficient and glass transition temperature to improve moldability, (B2O3 + Al2O3) / SiO2 is preferably 0.09 or greater, more preferably 0.1 or greater, more preferably greater than 0.13, more preferably 0.15 or greater, more preferably 0.17 or greater, more preferably 0.20 or greater, more preferably 0.23 or greater, and particularly preferably 0.24 or greater. The upper limit of (B2O3 + Al2O3) / SiO2 is preferably 0.6 or less, more preferably 0.5 or less, more preferably 0.4 or less, and particularly preferably 0.3 or less. If the value of (B2O3 + Al2O3) / SiO2 is too large, the absorption coefficient at frequencies from 0.1 THz to 3 THz tends to increase. Furthermore, weather resistance tends to decrease. Note that (B2O3 + Al2O3) / SiO2 refers to the value obtained by dividing the total content of B2O3 and Al2O3 by the total content of SiO2.

[0029] The total amount of Li2O+Na2O+K2O is greater than 0 mol ppm and less than 1000 mol ppm. By keeping the total amount of Li2O+Na2O+K2O within this range, it is possible to adjust the thermal expansion coefficient without increasing the absorption coefficient at frequencies from 0.1 THz to 3 THz. The upper limit is preferably 1000 mol ppm or less, more preferably 800 mol ppm or less, 600 mol ppm or less, 500 mol ppm or less, and particularly preferably 350 mol ppm or less. The lower limit is preferably greater than 0 mol ppm, more preferably 50 mol ppm or more, 100 mol ppm or more, and particularly preferably 150 mol ppm or more. If the total amount of Li2O+Na2O+K2O is too small, the meltability decreases, making it difficult to prepare the glass. Furthermore, bubbles tend to remain in the glass, reducing the linear transmittance of low-frequency light. If the total amount of Li2O+Na2O+K2O is too large, the absorption coefficient at frequencies from 0.1 THz to 3 THz tends to increase significantly. Furthermore, weather resistance is likely to decrease.

[0030] The preferred ranges of each of the components Li2O, Na2O, and K2O are as follows:

[0031] The upper limit of the Li2O content is preferably 1000 mol ppm or less, more preferably 800 mol ppm or less, 600 mol ppm or less, 400 mol ppm or less, particularly preferably 200 mol ppm or less, and the lower limit is preferably more than 0 mol ppm, more preferably 50 mol ppm or more, particularly preferably 100 mol ppm or more. If the Li2O content is too high, devitrification is likely to occur. On the other hand, if the content is too low, meltability is reduced, making it difficult to produce glass. In addition, bubbles are likely to remain in the glass, reducing the linear transmittance of low-frequency light.

[0032] The upper limit of the Na2O content is preferably 1000 mol ppm or less, and more preferably 800 mol ppm or less, 600 mol ppm or less, 400 mol ppm or less, and particularly preferably 200 mol ppm or less, and the lower limit is preferably more than 0 mol ppm, and more preferably 50 mol ppm or more, and particularly preferably 100 mol ppm or more. If the Na2O content is too high, devitrification is likely to occur. Furthermore, the absorption coefficient in the frequency range of 0.1 THz to 3 THz is particularly likely to increase. Furthermore, if the content is too low, the meltability decreases, making it difficult to produce the glass. Furthermore, bubbles are likely to remain in the glass, and the in-line transmittance of low-frequency light decreases.

[0033] The upper limit of the K2O content is preferably 1000 mol ppm or less, more preferably 800 mol ppm or less, 600 mol ppm or less, 400 mol ppm or less, 200 mol ppm or less, particularly preferably 100 mol ppm or less, and the lower limit is preferably more than 0 mol ppm, more preferably 10 mol ppm or more, particularly preferably 20 mol ppm or more. If the K2O content is too high, devitrification is likely to occur. On the other hand, if the content is too low, meltability is reduced, making it difficult to produce glass. Bubbles are likely to remain in the glass, reducing the linear transmittance of low-frequency light.

[0034] The total amount of MgO+CaO+SrO+BaO is greater than 0 mol ppm and less than 1000 mol ppm. By keeping the total amount of MgO+CaO+SrO+BaO within this range, it is possible to adjust the thermal expansion coefficient without increasing the absorption coefficient in the frequency range of 0.1 THz to 3 THz. The upper limit is preferably 1000 mol ppm or less, more preferably 800 mol ppm or less, 600 mol ppm or less, 500 mol ppm or less, and particularly preferably 350 mol ppm or less. The lower limit is preferably greater than 0 mol ppm, more preferably 100 mol ppm or more, 150 mol ppm or more, 200 mol ppm or more, and particularly preferably 250 mol ppm or more. If the total amount of MgO+CaO+SrO+BaO is too small, the meltability and devitrification resistance decrease, making it difficult to produce the glass. Furthermore, bubbles tend to remain in the glass, reducing the linear transmittance of low-frequency light. If the total amount of MgO+CaO+SrO+BaO is too large, the absorption coefficient in the frequency range of 0.1 THz to 3 THz tends to increase significantly.

[0035] The preferred ranges of the respective components MgO, CaO, SrO and BaO are as follows:

[0036] MgO is a component that reduces high-temperature viscosity and improves meltability. The upper limit of the MgO content is preferably 1000 mol ppm or less, more preferably 800 mol ppm or less, 600 mol ppm or less, 400 mol ppm or less, and particularly preferably 200 mol ppm or less, and the lower limit is preferably more than 0 mol ppm, more preferably 50 mol ppm or more, and particularly preferably 100 mol ppm or more. If the MgO content is too high, devitrification resistance tends to decrease. If the MgO content is too low, meltability and devitrification resistance decrease, making it difficult to produce glass. In addition, bubbles tend to remain in the glass, reducing the linear transmittance of low-frequency light.

[0037] CaO is a component that reduces high-temperature viscosity and improves meltability without lowering the strain point. The upper limit of the CaO content is preferably 1000 mol ppm or less, more preferably 800 mol ppm or less, 600 mol ppm or less, 400 mol ppm or less, 200 mol ppm or less, and particularly preferably 150 mol ppm or less, and the lower limit is preferably more than 0 mol ppm, more preferably 50 mol ppm or more, and particularly preferably 100 mol ppm or more. If the CaO content is too high, devitrification resistance tends to decrease. If the CaO content is too low, meltability and devitrification resistance decrease, making it difficult to produce glass. In addition, bubbles tend to remain in the glass, reducing the linear transmittance of low-frequency light.

[0038] SrO is a component that reduces high-temperature viscosity and improves devitrification resistance. The upper limit of the SrO content is preferably 1000 mol ppm or less, and more preferably 800 mol ppm or less, 600 mol ppm or less, 400 mol ppm or less, or 200 mol ppm or less, particularly preferably 100 mol ppm or less. The lower limit is preferably more than 0 mol ppm, and more preferably 10 mol ppm or more, 20 mol ppm or more, particularly preferably 30 mol ppm or more. If the SrO content is too high, devitrification resistance tends to decrease. If the SrO content is too low, meltability and devitrification resistance decrease, making it difficult to produce the glass. In addition, bubbles tend to remain in the glass, reducing the linear transmittance of low-frequency light.

[0039] BaO is a component that reduces high-temperature viscosity and particularly improves the formability of glass. The upper limit of the BaO content is preferably 1000 mol ppm or less, more preferably 800 mol ppm or less, 600 mol ppm or less, 400 mol ppm or less, or 200 mol ppm or less, particularly preferably 100 mol ppm or less, and the lower limit is preferably more than 0 mol ppm, more preferably 10 mol ppm or more, 20 mol ppm or more, particularly preferably 30 mol ppm or more. If the BaO content is too high, devitrification resistance tends to decrease. If the BaO content is too low, the formability, meltability, and devitrification resistance tend to decrease, making it difficult to produce glass. In addition, bubbles tend to remain in the glass, reducing the linear transmittance of low-frequency light.

[0040] From the viewpoint of enhancing the formability of the glass, the upper limit of the total amount of Li2O+Na2O+K2O+MgO+CaO+SrO+BaO is preferably 2000 mol ppm or less, more preferably 1500 mol ppm or less, 1000 mol ppm or less, 800 mol ppm or less, 650 mol ppm or less, and particularly preferably 500 mol ppm or less. The lower limit is preferably greater than 0 mol ppm, more preferably 100 mol ppm or more, 200 mol ppm or more, 300 mol ppm or more, 400 mol ppm or more, and particularly preferably 450 mol ppm or more. When the content of Li2O+Na2O+K2O+MgO+CaO+SrO+BaO satisfies the above range, the glass transition temperature (Tg) is likely to be lowered. When the content of Li2O+Na2O+K2O+MgO+CaO+SrO+BaO is too high, the absorption coefficient at frequencies from 0.1 THz to 3 THz is likely to increase. If the content is too low, the melting properties and devitrification resistance of the raw materials decrease, making it difficult to produce glass. Also, bubbles tend to remain in the glass, reducing the linear transmittance of low-frequency light.

[0041] In addition to the above components, other components may be incorporated as optional components into the glass of the present invention. From the viewpoint of accurately enjoying the effects of the present invention, the total content of components other than SiO2, B2O3, and Al2O3 is preferably 20 mol% or less, more preferably 19 mol% or less, 15 mol% or less, 10 mol% or less, and particularly preferably 5 mol% or less.

[0042] The upper limit of the total amount of SO3 + SnO2 is preferably 0.5 mol% or less, and more preferably 0.4 mol% or less, 0.3 mol% or less, 0.2 mol% or less, 0.15 mol% or less, and particularly preferably 0.1 mol% or less. The lower limit is preferably greater than 0 mol%, and more preferably 0.001 mol% or more, 0.01 mol% or more, 0.03 mol% or more, and particularly preferably 0.05 mol% or more. If the amount of SO3 + SnO2 is too high, bubble defects due to reboiling of SO2 gas are likely to occur. Coloring in the visible light range is also likely to occur. The absorption coefficient in the frequency range of 0.1 THz to 3 THz is also likely to increase. If the amount of SO3 + SnO2 is too low, it is difficult to obtain glass with good bubble quality. Furthermore, bubbles are likely to remain in the glass, reducing the in-line transmittance of low-frequency light.

[0043] SO3 is a component that exhibits a clarifying effect, improving bubble removal during melting. The upper limit of the SO3 content is preferably 0.5 mol% or less, more preferably 0.4 mol% or less, 0.3 mol% or less, 0.2 mol% or less, or 0.15 mol% or less, and particularly preferably 0.1 mol% or less. The lower limit is preferably greater than 0 mol%, more preferably 0.001 mol% or more, 0.01 mol% or more, 0.03 mol% or more, and particularly preferably 0.05 mol% or more. If the SO3 content is too high, bubble defects due to reboiling of SO2 gas are likely to occur. If the SnO2 content is too low, it is difficult to obtain glass with good bubble quality. In addition, bubbles are likely to remain in the glass, reducing the in-line transmittance of low-frequency light.

[0044] SnO2 is a component that exhibits a clarifying effect, improving bubble removal during melting. The upper limit of the SnO2 content is preferably 0.5 mol% or less, and more preferably 0.4 mol% or less, 0.3 mol% or less, 0.2 mol% or less, or 0.15 mol% or less, and particularly preferably 0.1 mol% or less. The lower limit is preferably greater than 0 mol%, and more preferably 0.001 mol% or more, 0.01 mol% or more, 0.03 mol% or more, and particularly preferably 0.05 mol% or more. If the SnO2 content is too high, coloration in the visible light range is likely to occur. Furthermore, the absorption coefficient in the frequency range of 0.1 THz to 3 THz is likely to increase. If the SnO2 content is too low, it becomes difficult to obtain glass with good bubble quality. Furthermore, bubbles are more likely to remain in the glass, reducing the in-line transmittance of low-frequency light.

[0045] The upper limit of the Fe2O3+Cr2O3+TiO2+ZrO2+MoO3 content is preferably 2000 mol ppm or less, more preferably 1500 mol ppm or less, 1000 mol ppm or less, 500 mol ppm or less, 100 mol ppm or less, and particularly preferably 50 mol ppm or less. The lower limit is preferably greater than 0 mol ppm, more preferably 10 mol ppm or more, and particularly preferably 20 mol ppm or more. If the Fe2O3+Cr2O3+TiO2+ZrO2+MoO3 content is too low, the meltability of the raw materials decreases, making it difficult to obtain glass. In addition, bubbles tend to remain in the glass, reducing the linear transmittance of low-frequency light. If the Fe2O3+Cr2O3+TiO2+ZrO2+MoO3 content is too high, the glass will exhibit coloration, making it unsuitable for use as an optical element capable of visible light alignment.

[0046] Fe2O3 is a component that reduces the viscosity of glass and improves the meltability and formability of glass. The upper limit of the Fe2O3 content is preferably 2000 mol ppm or less, more preferably 1500 mol ppm or less, 1000 mol ppm or less, 500 mol ppm or less, 100 mol ppm or less, particularly 50 mol ppm or less. The lower limit is preferably more than 0 mol ppm, more preferably 10 mol ppm or more, particularly 20 mol ppm or more. If the Fe2O3 content is too high, the glass will exhibit coloration and will not be suitable for use as an optical element capable of visible light alignment. If the Fe2O3 content is too low, the meltability of the glass will decrease, the viscosity of the glass melt will increase, making it difficult to clarify, and glass molding will be difficult, resulting in reduced productivity. In addition, bubbles will be more likely to remain in the glass, reducing the linear transmittance of low-frequency light.

[0047] Cr2O3 is a component that reduces the viscosity of glass and improves the meltability and formability of the glass. The upper limit of the Cr2O3 content is preferably 2000 mol ppm or less, more preferably 1500 mol ppm or less, 1000 mol ppm or less, 500 mol ppm or less, 100 mol ppm or less, particularly preferably 50 mol ppm or less. The lower limit is preferably more than 0 mol ppm, more preferably 10 mol ppm or more, particularly preferably 20 mol ppm or more. If the Cr2O3 content is too high, the glass will exhibit coloration and will not be suitable for use as an optical element capable of visible light alignment. If the Cr2O3 content is too low, the meltability of the glass will decrease, the viscosity of the glass melt will increase, making it difficult to clarify, and glass molding will be difficult, resulting in reduced productivity. In addition, bubbles will be more likely to remain in the glass, reducing the linear transmittance of low-frequency light.

[0048] TiO2 is a component that reduces the viscosity of glass and improves the meltability and formability of glass. The upper limit of the TiO2 content is preferably 2000 mol ppm or less, more preferably 1500 mol ppm or less, 1000 mol ppm or less, 500 mol ppm or less, 100 mol ppm or less, particularly preferably 50 mol ppm or less. The lower limit is preferably more than 0 mol ppm, more preferably 10 mol ppm or more, particularly preferably 20 mol ppm or more. If the TiO2 content is too high, the glass will exhibit coloration and will not be suitable for use as an optical element capable of visible light alignment. If the TiO2 content is too low, the meltability of the glass will decrease, the viscosity of the glass melt will increase, making it difficult to clarify, and glass molding will be difficult, resulting in reduced productivity. In addition, bubbles will be more likely to remain in the glass, reducing the linear transmittance of low-frequency light.

[0049] ZrO2 is a component that improves the Young's modulus and rigidity modulus of glass. The upper limit of the ZrO2 content is preferably 2000 mol ppm or less, more preferably 1500 mol ppm or less, 1000 mol ppm or less, 500 mol ppm or less, 100 mol ppm or less, particularly preferably 50 mol ppm or less, and the lower limit is preferably more than 0 mol ppm, more preferably 10 mol ppm or more, particularly preferably 20 mol ppm or more. If the ZrO2 content is too low, mullite crystals tend to precipitate and the glass tends to devitrify. In addition, the meltability of the glass decreases, the viscosity of the glass melt increases, making it difficult to refine, and glass molding becomes difficult, which tends to reduce productivity. On the other hand, if the ZrO2 content is too high, the meltability of the glass decreases, the viscosity of the glass melt increases, making it difficult to refine, glass molding becomes difficult, and productivity tends to reduce.

[0050] MoO3 is a component that reduces the water content in glass. In particular, by melting the raw material batch by electrical melting and adding MoO3, the water content in glass can be further reduced. Reducing the water content in glass increases the liquidus viscosity and strain point, thereby improving the devitrification resistance and heat resistance of the glass and increasing the transmittance of low-frequency light. The upper limit of the MoO3 content is preferably 2000 mol ppm or less, more preferably 1500 mol ppm or less, 1000 mol ppm or less, 500 mol ppm or less, 100 mol ppm or less, and particularly preferably 50 mol ppm or less. The lower limit is preferably greater than 0 mol ppm, more preferably 10 mol ppm or more, and particularly preferably 20 mol ppm or more. If the MoO3 content is too high, the glass will exhibit coloration and will not be suitable for use as an optical element capable of visible light alignment. If the MoO3 content is too low, the water content in the glass will not be sufficiently reduced, increasing the liquidus viscosity and strain point, and the devitrification resistance and heat resistance of the glass will tend to be reduced.

[0051] Water in glass is a component that increases the meltability of glass. The upper limit of the water content in glass is preferably 2 / mm or less, and is preferably 1.5 / mm or less, 1.2 / mm or less, 1 / mm or less, 0.9 / mm or less, 0.85 / mm or less, 0.8 / mm or less, 0.75 / mm or less, 0.7 / mm or less, 0.65 / mm or less, 0.6 / mm or less, 0.55 / mm or less, 0.54 / mm or less, 0.53 / mm or less, 0.52 / mm or less, 0.51 / mm or less, and particularly preferably 0.50 / mm or less. The lower limit is preferably 0.001 / mm or more, and is preferably 0.01 / mm or more, 0.02 / mm or more, 0.03 / mm or more, 0.04 / mm or more, 0.05 / mm or more, 0.06 / mm or more, 0.07 / mm or more, and particularly preferably 0.08 / mm or more. If the water content in the glass is too low, the meltability of the glass will decrease and the viscosity of the glass melt will increase, making it difficult to mold the glass and reducing productivity.If the water content in the glass is too high, the absorption coefficient at frequencies from 0.1 THz to 3 THz will tend to increase.

[0052] The β-OH value can be determined by measuring the transmittance of glass using an FT-IR Frontier (manufactured by Perkin Elmer) and using the following formula: The scan speed is 100 μm / min and the sampling pitch is 1 cm. -1 The number of scans is 10 per measurement.

[0053] β-OH value = (1 / X)log10(T1 / T2) X: Glass thickness (mm) T1: Reference wavelength 3846cm -1 Transmittance (%) T2: Hydroxyl group absorption wavelength 3600cm -1 Minimum transmittance (%) in the vicinity

[0054] Since low-frequency light is invisible, visible light lasers are sometimes used for optical system alignment. Therefore, the glass of the present invention preferably contains components that exhibit coloration in the visible wavelength range in a total amount of 1 mol % or less, preferably 0.5 mol % or less, and particularly preferably 0.1 mol % or less. This allows the glass of the present invention to be used as an optical element capable of visible light alignment. Examples of components that exhibit coloration in the visible wavelength range include, in addition to the aforementioned Fe2O3, Cr2O3, and TiO2, V2O5, CoO3, and NiO. In the present invention, the visible wavelength range refers to 400 nm to 800 nm.

[0055] In consideration of the environmental impact, the contents of As2O3, Sb2O3, PbO, Bi2O3 and F are each preferably less than 0.05 mol %.

[0056] The glass of the present invention preferably has the following properties:

[0057] The glass of the present invention exhibits high transmittance for low frequency light by having the above composition. In other words, the glass of the present invention can reduce the absorption coefficient for low frequency light by having the above composition. Specifically, the absorption coefficient at frequencies of 0.1 THz to 3 THz is 50 cm -1Less than or equal to 45cm -1 Preferably less than 40cm -1 Below, 35cm -1 Below, especially 30cm -1 If the absorption coefficient in the frequency range of 0.1 THz to 3 THz is too large, it becomes difficult to use it as a low-frequency light transmitting material. More specifically, if the absorption coefficient in the frequency range of 0.3 THz to 2.5 THz is 50 cm or less, -1 Preferably less than 45cm -1 Below, 40cm -1 Below, 35cm -1 Below, 30cm -1 Below, 25cm -1 Below, especially 22cm -1 It is preferable that:

[0058] In the above frequency range, more specifically, the absorption coefficient at a frequency of 2.5 THz is 50 cm -1 Preferably less than 40cm -1 Below, 30cm -1 Below, 25cm -1 Below, 20cm -1 Below, 15cm -1 Below, especially 13cm -1 It is preferable that the absorption coefficient at a frequency of 2 THz is 50 cm or less. -1 Preferably less than 40cm -1 Below, 30cm -1 Below, 25cm -1 Below, 20cm -1 Below, 15cm -1 Below, especially 10cm -1 It is preferable that the absorption coefficient at a frequency of 1.5 THz is 50 cm or less. -1 Preferably less than 40cm -1 Below, 30cm -1 Below, 20cm -1 Below, 16cm -1 Below, 13cm -1 Below, 10cm -1 Below, especially 7cm -1 It is preferable that the absorption coefficient at a frequency of 1 THz is 50 cm or less.-1 Preferably less than 40cm -1 Below, 30cm -1 Below, 20cm -1 Below, 10cm -1 Below, 5cm -1 Below, especially 3cm -1 It is preferable that the absorption coefficient at a frequency of 0.5 THz is 5 cm or less. -1 Preferably less than 3cm -1 Less than 2cm -1 Below, 1cm -1 Below, especially 0.8cm -1 It is preferable that the absorption coefficient at a frequency of 0.3 THz is 5 cm or less. -1 Preferably less than 3cm -1 Below, 2.5cm -1 Below, 2.0cm -1 Below, 1.5cm -1 Below, 1cm -1 Below, especially 0.5cm -1 It is preferable that:

[0059] The glass of the present invention has excellent formability due to its composition. As an index of formability, for example, the glass transition temperature (Tg) is preferably 1000°C or lower, more preferably 950°C or lower, 900°C or lower, 850°C or lower, 830°C or lower, and particularly preferably 800°C or lower. When the glass transition temperature (Tg) is within the above range, softening and deformation can be easily achieved at a relatively low temperature, thereby improving the formability of the glass. The lower limit of the glass transition temperature (Tg) is not particularly limited, but can be, for example, 400°C or higher, 500°C or higher, particularly 600°C or higher.

[0060] The glass of the present invention, having the above composition, can suppress thermal expansion and reduce deformation even in an environment with temperature changes. Therefore, the thermal expansion coefficient is 30×10 -7 / °C or less, and -7 / ℃ or less, 27×10 -7 / ℃ or less, 25×10 -7 / ℃ or less, especially 23.5×10 -7The lower limit of the thermal expansion coefficient is preferably 5×10 / °C or less. -7 / ℃ or more, 6×10 -7 / ℃ or more, especially 7×10 -7 / °C or more.

[0061] The glass of the present invention is suitable as a low-frequency light-transmitting material. For example, it is suitable as a terahertz wave-transmitting material. The glass of the present invention is also suitable as an optical element usable in low-frequency optical systems. For example, it is suitable as an optical element such as a lens, prism, filter, diffraction grating, optical fiber, cover glass, waveguide, or glass antenna substrate. Furthermore, the glass of the present invention is capable of receiving highly linear radio waves from any direction, and is therefore suitable for use as a cover glass for mobile communication devices, a TFT substrate for mobile communication devices, or a light source cover glass. Furthermore, because the glass of the present invention has a low thermal expansion coefficient, it is also suitable as a heat-resistant material. For example, the glass is also suitable for use in front windows of kerosene stoves, wood stoves, and the like, substrates for high-tech products such as color filters and image sensor substrates, support glass for circuit boards, interposer substrates, glass antenna substrates, setters for firing electronic components, light diffusers, furnace tubes for semiconductor manufacturing, masks for semiconductor manufacturing, optical lenses, components for dimension measurement, communication components, construction components, chemical reaction vessels, top plates for induction cooktops, heat-resistant tableware, heat-resistant covers, window glass for fire doors, components for astronomical telescopes, and space optics components. Furthermore, if strength is required for the above applications, tempering treatment may be performed. Specific examples include chemical tempering and air-cooling tempering. Because the content of Na2O, KO, and LiO2 is low, tempering by air-cooling tempering is preferred.

[0062] When used in the form of a plate, a thickness of 0.005 to 1 mm makes it suitable for use as a circuit board support glass, an interposer glass, or a glass antenna substrate. Furthermore, a thickness of 0.01 to 1 mm makes it suitable for use as a cover glass for mobile communication devices, a TFT substrate for mobile communication devices, or a light source cover glass. Furthermore, a thickness of 0.1 to 10 mm makes it suitable for use as an architectural window material, and in this case, it may be laminated with a resin to form a multi-layer structure.

[0063] When used in a fibrous form, the fiber can be suitably used to reinforce high-frequency circuit boards with a diameter of 0.001 to 0.1 mm. The fiber may be used in any form, including yarn, chopped, mat, or nonwoven fabric. It can also be suitably used as an optical fiber. In particular, when used as a waveguide for an optical fiber, it may be doped with rare earth elements or transition metals to form a laser medium.

[0064] When used in powder form, the average particle size (D 50 ) is 0.1 to 100 μm, it can be suitably used as a sealing glass paste or a reinforcing material for a resin-made terahertz transmitting component.

[0065] In this specification, the term "average particle size" refers to D50 (volume-based average particle size) and refers to a value measured using a laser diffraction scattering particle size distribution analyzer (SALD-2000J, manufactured by Shimadzu Corporation). [Example]

[0066] The present invention will be described below based on examples. Note that the following examples are merely illustrative and are not intended to limit the present invention in any way.

[0067] Table 1 shows Examples 1 and 2 of the present invention.

[0068] [Table 1] First, glass raw materials were mixed to prepare a glass batch having the glass composition shown in Table 1. The glass batch was placed in a crucible and melted. The melt was then poured out, formed into a plate, and slowly cooled to room temperature. The absorption coefficient (α) and glass transition temperature (Tg) of each sample were measured. The results are shown in Table 1.

[0069] The glass transition temperature (Tg) was measured using a macro-type differential thermal analyzer.

[0070] The absorption coefficients (α) at ​​frequencies of 0.3 THz, 0.5 THz, 1.0 THz, 1.5 THz, 2.0 THz, and 2.5 THz were measured by terahertz time-domain spectroscopy.

[0071] The thermal expansion coefficient (30 to 380° C.) was measured using a thermal expansion measuring device (dilato meter).

[0072] As shown in Table 1, in Example 1, the absorption coefficient in the range of 0.3 THz to 2.5 THz was 0.52 cm -1 ~21.90cm -1 The Tg is 713°C, and the thermal expansion coefficient is 15.0×10 -7 / °C. In Example 2, the absorption coefficient in the range of 0.3 THz to 2.5 THz was 0.50 cm -1 ~12.23cm -1 The Tg is 582°C, and the thermal expansion coefficient is 23.1×10 -7 / ℃. [Industrial Applicability]

[0073] The glass of the present invention is suitable as a low-frequency light transmitting material. The glass of the present invention is also suitable as an optical element that can be used in a low-frequency optical system, such as a lens, a prism, a filter, a diffraction grating, or an optical fiber.

Claims

1. The glass composition is SiO ２ +B ２ O ３ +Al ２ O ３ More than 0 mol% to 99 mol%, SiO ２ More than 0 mol% to less than 99 mol%, Li ２ O + Na ２ O+K ２ O 0 mol ppm to 1000 mol ppm, MgO + CaO + SrO + BaO 0 mol ppm to 1000 mol ppm, and an absorption coefficient at a frequency of 0.1 THz to 3 THz of 50 cm －１ Below is the glass.

2. SO ３ + SnO ２ The glass of claim 1 containing from greater than 0 mol % to 0.5 mol %.

3. Fe ２ O ３ +Cr ２ O ３ + TiO ２ + ZrO ２ +MoO ３ The glass of claim 1 containing from greater than 0 to 2000 molar ppm.

4. B ２ O ３ 0 mol% to 80 mol% Al ２ O ３ The glass according to any one of claims 1 to 3, containing 0 mol % to 80 mol %.

5. B ２ O ３ +Al ２ O ３ The glass according to any one of claims 1 to 3, containing more than 0 mol% to 80 mol%.

6. The absorption coefficient at a frequency of 1 THz is 30 cm －１ 4. The glass according to claim 1, wherein:

7. The absorption coefficient at a frequency of 0.3 THz is 5.0 cm －１ 4. The glass according to claim 1, wherein:

8. 4. The glass according to claim 1, having a glass transition temperature (Tg) of 1000° C. or lower.

9. The glass according to any one of claims 1 to 3, which is used as a low-frequency light transmitting material.

10. The glass according to any one of claims 1 to 3, which is used as an optical element.

11. The glass composition is SiO ２ +B ２ O ３ +Al ２ O ３ More than 0 mol% to 99 mol%, SiO ２ More than 0 mol% to less than 99 mol%, Li ２ O + Na ２ O+K ２ O 0 mol ppm to 1000 mol ppm, MgO + CaO + SrO + BaO 0 mol ppm to 1000 mol ppm, and an absorption coefficient at a frequency of 0.1 THz to 3 THz of 50 cm －１ Low frequency light transmitting materials, including glass, that are:

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