Glass

Abstract

To provide a glass with high Young's modulus and excellent resistance to devitrification, while having a low coefficient of expansion.SOLUTION: A glass 10 contains, in terms of mol% on an oxide basis, 20% or more of SiO2, has a total content of trivalent oxides Rx2O3 of 30% or more, has a ratio of the content of Al2O3 to the total content of the trivalent oxides Rx2O3 that is higher than 50%, and includes Ta2O5.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to glass.

Background Art

[0002] There are times when high Young's modulus glass is required. Patent Document 1 describes optical glass with a Young's modulus of 130 GPa or more.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, high Young's modulus glass may have high devitrification tendency or high coefficient of thermal expansion.

[0005] An object of the present invention is to provide a glass having a high Young's modulus, high devitrification resistance, and low coefficient of thermal expansion.

Means for Solving the Problems

[0006] The glass according to the present disclosure has, in terms of mol% based on oxides, a SiO2 content of 20% or more, a total content of trivalent oxide Rx2O3 of 30% or more, a ratio of the content of Al2O3 to the total content of trivalent oxide Rx2O3 higher than 50%, and contains Ta2O5.

Effects of the Invention

[0007] According to the present invention, a high Young's modulus, high devitrification resistance, and low coefficient of thermal expansion can be achieved.

Brief Description of the Drawings

[0008]

Figure 1

Embodiments for Carrying Out the Invention

[0009] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the present invention is not limited by this embodiment, and when there are a plurality of embodiments, those configured by combining each embodiment are also included. Also, numerical values include the range of rounding. Also, the numerical range represented by "~" means a numerical range including the numerical values before and after ~ as the lower limit value and the upper limit value, and the same meaning is referred to when using "~" hereinafter.

[0010] (Glass) FIG. 1 is a schematic diagram of the glass according to the present embodiment. As shown in FIG. 1, the glass 10 according to the present embodiment may be used for any purpose, but is preferably used as an optical glass used in an optical device or a glass substrate for supporting a member. When used as a glass substrate, the glass 10 may be used as a glass substrate for manufacturing a semiconductor package, and more specifically, may be used as a support glass substrate for manufacturing such as FOWLP. Note that FOWLP, etc. include Fan Out Wafer Level Package (FOWLP) and Fan Out Panel Level Package (FOPLP).

[0011] In FIG. 1, the glass 10 is flat, but the shape and thickness of the glass 10 may be arbitrary.

[0012] (Composition of Glass) Next, the preferred composition of the glass 10 will be described. In the following description, that a component is not contained or the content of a component is 0% may allow that the component is contained as an unavoidable impurity.

[0013] (SiO2) Glass 10 contains SiO2. In terms of the molar percentage based on oxides, the content of SiO2 in Glass 10 is 20% or more, preferably 25% or more, and more preferably 30% or more. Also, in terms of the molar percentage based on oxides, the content of SiO2 in Glass 10 is preferably 20% or more and 50% or less, more preferably 25% or more and 45% or less, and even more preferably 30% or more and 40% or less. When the content of SiO2 is 20% or more, the devitrification resistance and low expansion rate can be appropriately achieved, and when it is 50% or less, the Young's modulus can be increased.

[0014] (ZrO2) ZrO2 can increase the Young's modulus without significantly reducing the linear thermal expansion coefficient. Therefore, Glass 10 preferably does not contain ZrO2, but in terms of the molar percentage based on oxides, the content of ZrO2 may be 0.1% or more and 5% or less, may be 0.5% or more and 3% or less, and may be 1% or more and 2% or less. When the content of ZrO2 is within this range, high Young's modulus and high refractive index can be appropriately achieved while appropriately achieving devitrification resistance and low expansion rate.

[0015] (TiO2) TiO2 can increase the Young's modulus without significantly reducing the linear thermal expansion coefficient. Therefore, Glass 10 preferably does not contain TiO2, but in terms of the molar percentage based on oxides, the content of TiO2 may be 0.1% or more and 5% or less, may be 0.5% or more and 3% or less, and may be 1% or more and 2% or less. When the content of TiO2 is within this range, high Young's modulus and high refractive index can be appropriately achieved while appropriately achieving devitrification resistance and low expansion rate.

[0016] (Rx2O3) Here, let Rx be a trivalent metal and Rx2O3 be the oxide of the trivalent metal Rx. For example, Rx is at least one of B, Al, Y, Gd, La, In, Ga, and Nd. In this case, Rx2O3 has the effect of increasing the Young's modulus. Therefore, in the glass 10, it is preferable that the total content of Rx2O3 is 30% or more in terms of mol% based on the oxide. Further, since Rx2O3 is a component that increases the linear thermal expansion coefficient, it is preferable that the total content of Rx2O3 is 33% or more and 70% or less, preferably 35% or more and 65% or less, preferably 38% or more and 60% or less, and more preferably 40% or more and 55% or less. The total content of Rx2O3 refers to the total content of the trivalent oxide. When multiple types of trivalent oxides are included, it refers to the total content of those trivalent oxides. When one type of trivalent oxide is included, it refers to the content of that trivalent oxide. When the total content of Rx2O3 is 30% or more, a high Young's modulus and a high refractive index can be appropriately achieved. When it is 70% or less, devitrification resistance and a low expansion rate can be appropriately achieved.

[0017] (Al2O3 / Rx2O3) Here, the ratio of the content of Al₂O₃ in terms of mol% based on oxides to the total content of Rx₂O₃ in terms of mol% based on oxides in the glass 10 is defined as the ratio (Al₂O₃ / Rx₂O₃). Rx₂O₃ is a component that effectively increases the Young's modulus of the glass, and it is preferable that the content of Rx₂O₃ is higher. However, if the content of Rx₂O₃ is too high, the devitrification resistance will decrease, making it difficult to obtain the glass. As a result of intensive studies, it was found that the effects of Al₂O₃ and the other Rx₂O₃ on the devitrification of the glass are different. Therefore, in order to increase the Young's modulus while maintaining the devitrification resistance of the glass, it is preferable that the contents of Al₂O₃ and the other Rx₂O₃ are close to equal, that is, the ratio (Al₂O₃ / Rx₂O₃) is close to 50%. Also, among Rx₂O₃, Al₂O₃ has the effect of reducing the linear thermal expansion coefficient, so it is preferable that the ratio (Al₂O₃ / Rx₂O₃) is higher. In addition to the above, in order to control the refractive index, for the glass 10, it is preferable that the ratio (Al₂O₃ / Rx₂O₃) is higher than 50%, and is preferably 53% or more and 95% or less, more preferably 55% or more and 90% or less, still more preferably 58% or more and 80% or less, and even more preferably 60% or more and 75% or less. When the ratio (Al₂O₃ / Rx₂O₃) is within this range, a high Young's modulus and a high refractive index can be appropriately achieved.

[0018] (Al₂O₃) Al₂O₃ has the effect of increasing the Young's modulus and lowering the linear thermal expansion coefficient. Also, by setting the content of Al₂O₃ to 50% or less, it is possible to suppress the decrease in devitrification resistance. Therefore, for the glass 10, in terms of mol% based on oxides, it is preferable that the content of Al₂O₃ is 15% or more and 50% or less, more preferably 20% or more and 40% or less, still more preferably 23% or more and 35% or less, and even more preferably 25% or more and 33% or less. When the content of Al₂O₃ is within this range, a high Young's modulus and a high refractive index can be appropriately achieved while appropriately achieving devitrification resistance and a low expansion rate.

[0019] (B₂O₃) B2O3 suppresses devitrification due to the crystallization of glass, facilitating production and having the effect of controlling the Young's modulus. Therefore, in the glass 10, in terms of mol% based on oxides, the content of B2O3 is preferably 0% or more and 30% or less, more preferably 1% or more and 25% or less, still more preferably 2% or more and 20% or less, even more preferably 3% or more and 15% or less, and still even more preferably 4% or more and 10% or less. By making the content of B2O3 within this range, high Young's modulus and high refractive index can be appropriately achieved while appropriately achieving devitrification resistance and low expansion coefficient.

[0020] (Y2O3) Y2O3 has the effect of increasing the Young's modulus, suppressing deflection, and increasing the refractive index. Therefore, the glass 10 may not contain Y2O3 (the content of Y2O3 is 0 mol%), or may contain Y2O3. Also, by making the content of Y2O3 30% or less, the linear thermal expansion coefficient can be controlled and the decrease in devitrification resistance can be suppressed. Therefore, in the glass 10, in terms of mol% based on oxides, the content of Y2O3 is preferably 0% or more and 30% or less, more preferably 3% or more and 25% or less, still more preferably 5% or more and 23% or less, and even more preferably 7% or more and 18% or less. By making the content of Y2O3 within this range, high Young's modulus and high refractive index can be appropriately achieved while appropriately achieving devitrification resistance and low expansion coefficient.

[0021] (Gd2O3) Gd2O3 has the effect of increasing the Young's modulus to suppress deflection and increasing the refractive index. Therefore, the glass 10 may not contain Gd2O3 (the content of Gd2O3 is 0 mol%), but may also contain Gd2O3. Further, by setting the content of Gd2O3 to 30% or less, the linear thermal expansion coefficient can be controlled and the deterioration of devitrification resistance can be suppressed. Therefore, for the glass 10, in terms of mol% based on oxides, the content of Gd2O3 is preferably 0% or more and 30% or less, more preferably 3% or more and 25% or less, still more preferably 5% or more and 23% or less, and even more preferably 7% or more and 18% or less. By setting the content of Gd2O3 within this range, high Young's modulus and high refractive index can be appropriately achieved while appropriately achieving devitrification resistance and low expansion rate.

[0022] (La2O3) La2O3 has the effect of increasing the Young's modulus to suppress deflection and increasing the refractive index. Therefore, the glass 10 may not contain La2O3 (the content of La2O3 is 0 mol%), but may also contain La2O3. Further, by setting the content of La2O3 to 30% or less, the linear thermal expansion coefficient can be controlled and the deterioration of devitrification resistance can be suppressed. Therefore, for the glass 10, in terms of mol% based on oxides, the content of La2O3 is preferably 0% or more and 30% or less, more preferably 3% or more and 25% or less, still more preferably 5% or more and 23% or less, and even more preferably 7% or more and 18% or less. By setting the content of La2O3 within this range, high Young's modulus and high refractive index can be appropriately achieved while appropriately achieving devitrification resistance and low expansion rate.

[0023] (In2O3) In2O3 may affect the living body and its price is very high. Therefore, it is preferable that the glass 10 does not contain In2O3. However, when use is necessary, in terms of mol% based on oxides, the content of In2O3 is preferably 0.01% or more and 5% or less, more preferably 0.1% or more and 3% or less, and even more preferably 0.5% or more and 1% or less.

[0024] (RyO) Here, Ry is a divalent metal, and RyO is an oxide of the divalent metal Ry. For example, Ry is at least one of Mg, Ca, Sr, Ba, and Zn. RyO is an important component for controlling manufacturing characteristics such as the solubility of the glass and the devitrification resistance. Therefore, in the glass 10, the total content of RyO is preferably 5% or more, more preferably 7% or more and 30% or less, still more preferably 9% or more and 25% or less, and even more preferably 11% or more and 22% or less, in terms of mol% based on oxides. The total content of RyO refers to the total content of divalent oxides. When there are multiple types of divalent oxides, it refers to the total content of those divalent oxides. When there is one type of divalent oxide, it refers to the content of that divalent oxide. By the total content of RyO being within this range, high Young's modulus and high refractive index can be appropriately achieved while appropriately achieving devitrification resistance and low expansion coefficient.

[0025] (MgO / RyO) Here, the ratio of the content of MgO in terms of mol% based on oxides to the total content of RyO in terms of mol% based on oxides in the glass 10 is defined as the ratio (MgO / RyO). The higher the ratio (MgO / RyO), the more effective it is to increase the Young's modulus of the glass and decrease the linear expansion coefficient. Also, in order to maintain the refractive index, the ratio (MgO / RyO) is preferably 95% or less. Therefore, in the glass 10, the ratio (MgO / RyO) is preferably 45% or more, more preferably 45% or more and 95% or less, still more preferably 50% or more and 90% or less, even more preferably 55% or more and 85% or less, and even more preferably 60% or more and 80% or less. By the ratio (MgO / RyO) being within this range, high Young's modulus and high refractive index can be appropriately achieved while appropriately achieving devitrification resistance and low expansion coefficient.

[0026] (MgO) MgO has the effect of increasing the Young's modulus while enhancing solubility. It also has the effect of reducing the linear thermal expansion coefficient. On the other hand, by setting the MgO content to 30% or less, devitrification resistance can be controlled. In glass 10, in terms of mol% based on oxides, the MgO content is preferably 1% or more and 30% or less, more preferably 3% or more and 28% or less, still more preferably 5% or more and 25% or less, even more preferably 8% or more and 23% or less, and still more preferably 10% or more and 20% or less. When the MgO content is within this range, high Young's modulus and high refractive index can be appropriately achieved while appropriately achieving devitrification resistance and low expansion rate.

[0027] (CaO) CaO is an oxide of Group 2 elements. It has the characteristics of increasing the Young's modulus after MgO and not excessively reducing the linear thermal expansion coefficient. Furthermore, it also has the characteristic of being less likely to increase the liquidus temperature compared to MgO. In glass 10, in terms of mol% based on oxides, the CaO content is preferably 30% or less, more preferably 0.1% or more and 25% or less, still more preferably 0.5% or more and 20% or less, even more preferably 1% or more and 15% or less, still more preferably 2% or more and 10% or less, and still more preferably 3% or more and 7% or less. When the CaO content is within this range, high Young's modulus and high refractive index can be appropriately achieved while appropriately achieving devitrification resistance and low expansion rate.

[0028] (ZnO) ZnO has the effect of improving the solubility of the glass and increasing the Young's modulus. Therefore, in glass 10, in terms of mol% based on oxides, the ZnO content is preferably 30% or less, more preferably 0.1% or more and 25% or less, still more preferably 0.5% or more and 20% or less, even more preferably 1% or more and 15% or less, still more preferably 2% or more and 10% or less, and still more preferably 3% or more and 7% or less. When the ZnO content is within this range, high Young's modulus and high refractive index can be appropriately achieved while appropriately achieving devitrification resistance and low expansion rate.

[0029] (Ta2O5) Among the oxide components that make up the glass, Ta2O5 is one of the most effective components for increasing the Young's modulus. It also has a large effect of increasing the refractive index and a large effect of lowering the linear thermal expansion coefficient. Therefore, it is preferable to contain Ta2O5 as much as possible. On the other hand, Ta2O5 is an expensive oxide and also reduces the devitrification resistance of the glass. Therefore, in the glass 10, it is preferable that the content of Ta2O5 is 30% or less in terms of mol% based on oxides. Also, in the glass 10, the content of Ta2O5 is preferably 5% or more, more preferably 7% or more and 30% or less, more preferably 9% or more and 28% or less, more preferably 11% or more and 25% or less, more preferably 13% or more and 23% or less, and even more preferably 15% or more and 21% or less. By setting the content of Ta2O5 within this range, it is possible to appropriately achieve a high Young's modulus and a high refractive index while appropriately achieving devitrification resistance and a low expansion rate.

[0030] (Content ratio of each component) Next, the preferable relationship of the content of each oxide in the glass 10 will be described.

[0031] (SiO2 / Al2O3) Let the ratio of the content of SiO2 in terms of mol% based on oxides to the content of Al2O3 in terms of mol% based on oxides in the glass 10 be the ratio (SiO2 / Al2O3). In this case, in the glass 10, the ratio (SiO2 / Al2O3) is preferably 80% or more, more preferably 90% or more and 150% or less, even more preferably 95% or more and 145% or less, more preferably 100% or more and 140% or less, more preferably 110% or more and 135% or less, and even more preferably 120% or more and 130% or less. By setting the ratio (SiO2 / Al2O3) within this range, it is possible to appropriately achieve a high Young's modulus and a high refractive index while appropriately achieving devitrification resistance and a low expansion rate.

[0032] (Al2O3 + Y2O3) The glass 10 preferably has a total content of Al₂O₃ and Y₂O₃ of 20% or more, more preferably 25% or more and 70% or less, still more preferably 28% or more and 65% or less, still more preferably 30% or more and 60% or less, still more preferably 35% or more and 55% or less, and even more preferably 40% or more and 50% or less, in terms of mol% based on oxides. By the total content of Al₂O₃ and Y₂O₃ being within this range, high Young's modulus and high refractive index can be appropriately achieved while appropriately achieving devitrification resistance and low expansion rate.

[0033] (Y₂O₃ / Al₂O₃) The ratio of the content of Y₂O₃ in terms of mol% based on oxides to the content of Al₂O₃ in terms of mol% based on oxides in the glass 10 is defined as the ratio (Y₂O₃ / Al₂O₃). In this case, the glass 10 preferably has a ratio (Y₂O₃ / Al₂O₃) of 0% or more and 100% or less, more preferably 10% or more and 80% or less, still more preferably 20% or more and 70% or less, and even more preferably 30% or more and 60% or less. By the ratio (Y₂O₃ / Al₂O₃) being within this range, high Young's modulus and high refractive index can be appropriately achieved while appropriately achieving devitrification resistance and low expansion rate.

[0034] (Al₂O₃ + Ta₂O₅) The glass 10 preferably has a total content of Al₂O₃ and Ta₂O₅ of 25% or more and 60% or less, more preferably 30% or more and 58% or less, still more preferably 35% or more and 56% or less, still more preferably 40% or more and 54% or less, still more preferably 43% or more and 52% or less, and even more preferably 45% or more and 50% or less, in terms of mol% based on oxides. By the total content of Al₂O₃ and Ta₂O₅ being within this range, high Young's modulus and high refractive index can be appropriately achieved while appropriately achieving devitrification resistance and low expansion rate.

[0035] (Ta₂O₅ / Al₂O₃) Let the ratio of the content of Ta2O5 in terms of mol% based on oxides to the content of Al2O3 in terms of mol% based on oxides in glass 10 be the ratio (Ta2O5 / Al2O3). In this case, for glass 10, the ratio (Ta2O5 / Al2O3) is preferably 0% or more and 200% or less, more preferably 10% or more and 150% or less, still more preferably 20% or more and 100% or less, even more preferably 30% or more and 85% or less, even more preferably 33% or more and 80% or less, even more preferably 40% or more and 75% or less, even more preferably 45% or more and 73% or less, even more preferably 50% or more and 70% or less, and still more preferably 55% or more and 67% or less. When the ratio (Ta2O5 / Al2O3) is within this range, high Young's modulus and high refractive index can be appropriately achieved, while devitrification resistance and low expansion rate can also be appropriately achieved.

[0036] (Properties of the glass) Next, the properties of glass 10 will be described.

[0037] (Young's modulus) The Young's modulus of glass 10 is preferably 130 GPa or more, more preferably 135 GPa or more and 180 GPa or less, still more preferably 140 GPa or more and 170 GPa or less, and even more preferably 147 GPa or more and 165 GPa or less. By making the Young's modulus this high, glass 10 can be made highly rigid. Such glass 10 with a high Young's modulus is suitable for applications such as optical glass and support substrates. If the Young's modulus is too high, cutting, grinding, and polishing processes will become difficult. Note that the Young's modulus can be measured based on the propagation of ultrasonic waves using a 38DL PLUS manufactured by OLYMPUS.

[0038] (Refractive index n d ) The refractive index n of glass 10 d is preferably 1.70 or more, more preferably 1.73 or more and 2.5 or less, and still more preferably 1.75 or more and 2.2 or less. The refractive index n dBy being within this range, it has a high refractive index with respect to visible light, and appropriate optical properties can be imparted to the glass 10. Note that the refractive index n d refers to the refractive index at the d-line of helium (wavelength 587.6 nm). The refractive index n d can be measured by the V-block method.

[0039] (Linear thermal expansion coefficient) The linear thermal expansion coefficient of the glass 10 is preferably 6.0 ppm / °C or less, more preferably 3.0 ppm / °C or more and 5.8 ppm / °C or less, still more preferably 3.5 ppm / °C or more and 5.6 ppm / °C or less, still more preferably 3.7 ppm / °C or more and 5.3 ppm / °C or less, and still more preferably 4.0 ppm / °C or more and 5.0 ppm / °C or less. By having such a low linear thermal expansion coefficient, deformation due to heat can be appropriately suppressed, and displacement in position and change in chromatic aberration due to temperature change can also be suppressed in optical glass applications. Such glass 10 with a low linear thermal expansion coefficient is suitable for uses such as optical glass and support substrates. The linear thermal expansion coefficient α is the average thermal expansion coefficient in the range of 50°C to 200°C, and is a value measured in accordance with DIN-51045-1 as the standard for thermal expansion measurement. For example, using a thermomechanical analyzer DIL 402 Expedis Supreme manufactured by NETZSCH as the measuring device, measure in the range of 30°C to 300°C, and the average thermal expansion coefficient in the range of 50°C to 200°C may be used as the linear thermal expansion coefficient.

[0040] (Specific gravity) The specific gravity of the glass 10 is preferably 3.0 g / cm 3 or more and 6.0 g / cm 3 or less, more preferably 3.5 g / cm 3 or more and 5.5 g / cm 3 or less, still more preferably 4.0 g / cm 3 or more and 5.1 g / cm 3 or less, still more preferably 4.5 g / cm 3 or more and 4.9 g / cm 3It is more preferable that the following holds. Since the specific gravity is thus low, the handling of the glass 10 becomes easy. Note that the specific gravity d can be measured by the Archimedes method.

[0041] (Method for manufacturing glass) The glass 10 may be manufactured by any method. For example, it is manufactured by the following method. First, raw materials such as silica sand and soda ash, which are raw materials of the compounds contained in the glass 10, are heated and melted at a predetermined temperature (for example, 1500°C to 1600°C). Then, after clarifying the molten raw material (glass), a forming step of forming it into a plate shape is executed. The formed glass has the composition range of the glass 10 described above on an oxide basis. Then, the glass 10 is manufactured by performing a slow cooling step on the glass formed in the forming step. Note that the manufacturing method of the glass 10 is not limited to the above and may be arbitrary. For example, the slow cooling step is not essential. Also, various methods can be adopted for the forming step when manufacturing the glass 10. Examples include the fusion casting method, the down-draw method (for example, the overflow down-draw method, the slot down method, and the redraw method), the float method, the roll-out method, and the press method. Note that since the glass 10 of the present embodiment has sufficient devitrification resistance, it can be manufactured by a method other than the so-called containerless method.

[0042] (Effects of the present disclosure) In the glass 10 according to the first aspect of the present disclosure, in terms of mol% representation on an oxide basis, the content of SiO2 is 20% or more, the total content of the trivalent oxide Rx2O3 is 30% or more, the ratio of the content of Al2O3 to the total content of the trivalent oxide Rx2O3 is higher than 50%, and it contains Ta2O5. Since the glass 10 of the present disclosure has such a composition, it has a high Young's modulus and devitrification resistance, and can have a low thermal expansion rate. Furthermore, the glass 10 of the present disclosure can also have a high refractive index by having such a composition.

[0043] The glass 10 according to the second aspect of the present disclosure is the glass 10 according to the first aspect, and preferably has a SiO2 content of 25% or more and a Ta2O5 content of 5% or more in terms of mol% based on oxides. Since the glass 10 of the present disclosure has such a composition, it can have a high Young's modulus, devitrification resistance, and refractive index, and a low coefficient of thermal expansion.

[0044] The glass 10 according to the third aspect of the present disclosure is the glass 10 according to the first aspect or the second aspect, and preferably has a total content of divalent oxide RyO of 5% or more, and the ratio of the content of MgO to the total content of divalent oxide RyO is preferably 45% or more and 95% or less. Since the glass 10 of the present disclosure has such a composition, it can have a high Young's modulus, devitrification resistance, and refractive index, and a low coefficient of thermal expansion.

[0045] The glass 10 according to the fourth aspect of the present disclosure is the glass 10 according to any one of the first aspect to the third aspect, and preferably has a Young's modulus of 130 GPa or more and a linear coefficient of thermal expansion of 6.0 ppm / °C or less. The glass 10 of the present disclosure can achieve a high Young's modulus and a low coefficient of thermal expansion.

[0046] The glass 10 according to the fifth aspect of the present disclosure is the glass 10 according to any one of the first aspect to the fourth aspect, and the refractive index n d is preferably 1.70 or more. The glass 10 of the present disclosure can achieve a high refractive index.

[0047] (Examples) Next, examples will be described. The table shows the glasses of each example. Note that the embodiments may be changed as long as the effects of the invention are achieved.

[0048]

Table 1

[0049] (Example 1) In Example 1, glass having the composition shown in Table 1 was produced. In Example 1, using the melt casting method, a green sheet with a diameter of 30 mm and a thickness of 10 mm was manufactured. Next, a plurality of sheets with a diameter of 20 mm and a thickness of 1 mm were cut out from the center of the green sheet. Both sides of these sheets were polished using cerium oxide as an abrasive to obtain glass.

[0050] Regarding the glass of Example 1, specific gravity, Young's modulus, coefficient of linear thermal expansion (CTE), and refractive index n d were measured. The measurement method used was the method described in this embodiment. The density ρ (g / cm 3 ) was measured. The density was measured by the Archimedes method. The measurement results of each are shown in Table 1.

[0051] (Examples 2 to 23) In Examples 2 to 23, glass was produced in the same manner as in Example 1, except that the composition of the glass was as shown in Table 1. However, in Examples 22 to 23, since the devitrification property was high, glass with a diameter of 3 mm was produced by the containerless method. The measurement results of each example are shown in Table 1.

[0052] (Evaluation) Regarding the glass of each example, evaluation of Young's modulus, thermal expansion rate, and devitrification resistance was performed.

[0053] In the evaluation of Young's modulus, a Young's modulus of 130 GPa or more was considered a pass, and a Young's modulus of less than 130 GPa was considered a fail. In the evaluation of the thermal expansion rate, a coefficient of linear thermal expansion of 6 ppm / °C or less was considered a pass, and a case where the coefficient of linear thermal expansion was higher than 6 ppm / °C was considered a fail. In the evaluation of devitrification resistance, the glass was evaluated by visual and microscopic observation. When the entire obtained glass had transparency, it was considered good and passed, and when a cloudy part or crystal derived from a crystal was observed in the glass, it was considered no and failed.

[0054] As shown in Table 1, in Examples 1 to 15 which are the examples of the present invention, the evaluations of Young's modulus, coefficient of thermal expansion, and devitrification resistance are all qualified, and it can be seen that the Young's modulus and devitrification resistance are high and the coefficient of thermal expansion is low. On the other hand, in Comparative Examples 16 to 23, at least one of the evaluations of Young's modulus, coefficient of thermal expansion, and devitrification resistance is unqualified, and it can be seen that the Young's modulus and devitrification resistance cannot be high and the coefficient of thermal expansion cannot be low.

[0055] As described above, the embodiments of the present invention have been described, but the embodiments are not limited by the content of these embodiments. In addition, the above-described components include those that can be easily assumed by those skilled in the art, substantially the same ones, and those within the so-called equivalent range. Furthermore, the above-described components can be combined as appropriate. Furthermore, various omissions, substitutions, or changes of the components can be made without departing from the gist of the above-described embodiments.

Explanation of Reference Signs

[0056] 10 glass

Claims

**Claim 1** In terms of molar% based on oxides, SiO ２ has a content of 20% or more, Trivalent oxide Rx ２ O ３ has a total content of 30% or more, Trivalent oxide Rx ２ O ３ The ratio of the content of Al to the total content of ２ O ３ is higher than 50%, Ta ２ O ５ containing glass. **Claim 2** In terms of molar% based on oxides, SiO ２ The content of which is 25% or more, Ta ２ O ５ with a content of 5% or more the glass according to Claim 1. **Claim 3** In terms of molar% based on oxides, the total content of divalent oxide RyO is 5% or more, and the ratio of the content of MgO to the total content of divalent oxide RyO is 45% or more and 95% or less, the glass according to Claim 1 or Claim 2. **Claim 4** The Young's modulus is 130 GPa or more and the linear thermal expansion coefficient is 6.0 ppm / °C or less, the glass according to Claim 1 or Claim 2. **Claim 5** Refractive index n ｄ is 1.70 or more, the glass according to Claim 1 or Claim 2.

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