Yttria-containing glass substrate

Abstract

A glass substrate comprises: about 45 mol% to about 70 mol% SiO2, about 15 mol% to about 30 mol% Al2O3, about 7 mol% to about 20 mol% Y2O3, and, depending on the circumstances, about 0 mol% to about 9 mol% La2O3. The glass substrate has a high modulus and fracture toughness.

Description

Technical Field

[0001] This application claims priority to U.S. Provisional Patent Application No. 62 / 863,550, filed June 19, 2019, which is based on which application is incorporated herein by reference in its entirety.

[0002] In general, this disclosure relates to glass compositions. More specifically, the subject matter of this disclosure pertains to glass substrates with high modulus and fracture toughness. Prior Technology

[0003] Flat or curved substrates made of optically transparent materials such as glass are used in flat panel displays, photovoltaic devices, and other suitable applications. Thin-film transistors (TFTs) can be fabricated on glass substrates for display applications. To meet processing and performance requirements, the glass composition used in display applications needs to have optical clarity, good thermal and mechanical properties, and dimensional stability. Furthermore, the diffusion of metal ions into the thin-film transistor can damage it and must be avoided.

[0004] Hard glass is also used in data recording discs, such as magnetic disks, optical disks, and memory disks in hard disk drives (HDDs). The demand for higher data storage capacity and performance in memory disks has also driven the demand for glass compositions with improved performance.

[0005] Glass is a brittle material and sometimes breaks during use. The breaking toughness of commercially available glass is typically close to or below 0.8 MPa*m0.5. There is still a need for glass with high breaking toughness to improve damage resistance and / or drop performance. Summary of the Invention

[0006] This disclosure provides glass compositions, glass substrates, methods of manufacturing the same, and methods of using the same. This disclosure also provides articles comprising such glass compositions or glass substrates, and apparatus comprising such glass substrates (having such glass compositions).

[0007] According to some embodiments, the glass substrate comprises: SiO2 of approximately 45 mol% to approximately 70 mol%; Al₂O₃: approximately 15 mol% to approximately 30 mol% Y₂O₃ of approximately 7 mol% to approximately 20 mol%; and La2O3, from 0 mol% to approximately 9 mol%, depending on the situation.

[0008] In some embodiments, the glass substrate comprises about 27 mol% to about 43 mol% of R2O3, wherein the R2O3 comprises Al2O3, Y2O3, and La2O3 in total. Examples of suitable ranges for the R2O3 content include, but are not limited to: about 28 mol% to about 40 mol%, about 30 mol% to about 40 mol%, or about 32 mol% to about 38 mol%. In some embodiments, the [(Y2O3 + La2O3) / Al2O3] molar ratio of the glass substrate is in the range of about 0.3 to about 1.7, for example, from about 0.5 to about 1.7, or from about 1 to about 1.5.

[0009] The glass substrate contains any suitable range of SiO2. Examples of suitable ranges include, but are not limited to: about 50 mol% to about 70 mol%, about 52 mol% to about 70 mol%, about 52 mol% to about 66 mol%, about 54 mol% to about 66 mol%, or about 60 mol% to about 66 mol%.

[0010] In some embodiments, the Al2O3 content is equal to or greater than 15 mol%. Examples of suitable ranges of Al2O3 include, but are not limited to: about 16 mol% to about 30 mol%, about 17 mol% to about 30 mol%, about 18 mol% to about 30 mol%, about 18 mol% to about 28 mol%, or about 18 mol% to about 25 mol%.

[0011] In some embodiments, the content of Y₂O₃ is equal to or greater than 7 mol%. Examples of suitable ranges of Y₂O₃ include, but are not limited to: about 8 mol% to about 20 mol%, about 9 mol% to about 20 mol%, about 7 mol% to about 16 mol%, about 7 mol% to about 15 mol%, about 8 mol% to about 16 mol%, or about 10 mol% to about 16 mol.

[0012] La₂O₃ may be present, depending on the situation. Examples of suitable ranges for La₂O₃ include, but are not limited to: about 0.1 mol% to about 9 mol%, about 1 mol% to about 9 mol%, about 2 mol% to about 9 mol%, or about 3 mol% to about 9 mol%. When the glass substrate contains La₂O₃, such glass substrate does not contain B₂O₃.

[0013] In some other embodiments, the glass substrate further comprises 0 mol% to about 6 mol% of B₂O₃, for example, 0.1 mol% to about 6 mol% of B₂O₃, or 0.1 mol% to about 1 mol% of B₂O₃. When B₂O₃ is added, the glass substrate is substantially free of La₂O₃.

[0014] The glass substrate may further contain 0 mol% to about 6 mol% of MgO, for example, 0 to about 5 mol%, 0 to about 4 mol%, 0 to about 3 mol%, about 0.1% to about 5 mol%, about 0.1% to about 4 mol%, about 0.1% to about 3 mol%.

[0015] The glass substrate may further contain 0 mol% to about 12 mol% of alkali metal oxides, such as Li₂O, Na₂O, K₂O, or combinations thereof.

[0016] In some embodiments, the molar percentage difference of (Al₂O₃–R₂O–RO) is in the range of about 7 to about 22, for example, about 7.1 to about 21.6, about 10 to about 20, or about 15 to about 20. R₂O comprises an alkali metal oxide selected from the group consisting of Na₂O, K₂O, and any combination thereof. RO comprises an alkaline earth metal oxide selected from the group consisting of MgO, SrO, BaO, and any combination thereof. The glass substrate is substantially free of CaO.

[0017] In some embodiments, the glass substrate is substantially free of CaO, Eu2O3, Nb2O3, Si3N4, WO3, ZrO4 and TiO2, except for CaO.

[0018] According to some embodiments, this disclosure provides a glass substrate that is substantially composed of the following components: SiO2 of approximately 45 mol% to approximately 70 mol%; Al₂O₃: approximately 15 mol% to approximately 30 mol% Y₂O₃: approximately 7 mol% to approximately 20 mol% 0 mol% to approximately 9 mol% of La2O3; 0 mol% to about 6 mol% of MgO; and Alkali metal oxides of 0 mol% to about 12 mol%, selected from the group consisting of Li₂O, Na₂O, K₂O and combinations thereof.

[0019] The glass substrate contains about 27 moles to about 43 moles of R₂O₃, wherein the R₂O₃ comprises Al₂O₃, Y₂O₃, and La₂O₃. The glass substrate has a mole ratio of [(Y₂O₃ + La₂O₃) / Al₂O₃] in the range of about 0.3 to about 1.7. As described herein, La₂O₃, B₂O₃, MgO, and alkali metal oxides (such as Na₂O and K₂O) are present as appropriate. In some embodiments, when the composition contains La₂O₃, such a composition is substantially free of B₂O₃.

[0020] The glass substrates provided in this disclosure have favorable properties such as ease of handling and excellent mechanical properties including high modulus and high breaking toughness. In some embodiments, the breaking toughness (KIC) of the glass substrate is in the range of about 0.87 to about 2.0 MPa·m⁻¹⁰.⁵. The glass substrate also has a Young's modulus in the range of about 100 GPa to about 140 GPa, and a shear modulus in the range of about 30 GPa to about 60 GPa.

[0021] The glass substrate provided in this disclosure has an amorphous structure that provides such fracture toughness and high modulus. However, in some other embodiments, the glass substrate may be made into a crystalline structure to have further improved modulus and fracture toughness.

[0022] In other embodiments, this disclosure also provides methods for manufacturing and using the glass substrates described herein, glass articles (or components) comprising such glass substrates, and apparatus comprising glass substrates or glass articles.

[0023] Examples of glass articles include, but are not limited to: panels, substrates, information recording discs or memory discs, covers, backplates, and any other components used in electronic devices. For example, in some embodiments, a glass composition or glass substrate may be used as a substrate for a memory disc or as a substrate for a cover or backplate in a display device. Simple Explanation of the Diagram

[0024] The present disclosure is best understood from the following detailed description when read in conjunction with the accompanying drawings. It should be emphasized that, by convention, these drawings are used only to illustrate some embodiments.

[0025] Figure 1 graphically depicts the relationship between the softening point and the difference between the softening point and the strain point of an exemplary glass composition according to some embodiments. Implementation

[0026] This description of exemplary embodiments is to be read in conjunction with the accompanying drawings, which are considered an integral part of the entire written description. For the purposes described below, it should be understood that alternative variations and embodiments may be taken of the embodiments described below. It should also be understood that the specific articles, components, and / or methods described herein are exemplary and should not be considered limiting. All documents referenced in this disclosure are incorporated herein by reference.

[0027] Open-ended terms such as "include" or "containing" mean "comprising." These open-ended transitional phrases are used to introduce an open list of elements, method steps, etc., which do not exclude additional, undescribed elements or method steps. It should be understood that regardless of whether any embodiment is described using the language "comprising," similar embodiments described as "consisting of" and / or "consisting essentially of" are also provided.

[0028] The transitional phrase "composed of" and its variations exclude any undocumented elements, steps, or components, except for impurities that are usually associated with them.

[0029] The transitional phrase "consists essentially of" or variations such as "consist essentially of" or "consisting essentially of" excludes any undescribed elements, steps, or components, except those that do not substantially alter the basic or novel characteristics of the method, structure, or composition referred to.

[0030] In this disclosure, the singular forms "a" and "the" include plural references, and reference to a particular numerical value includes at least that particular numerical value, unless the context clearly indicates otherwise. When a value is expressed as an approximation by using the antecedent "about," it will be understood that the particular value forms another embodiment. As used herein, "about X" (where X is a numerical value) preferably refers to ±10% (inclusive) of the listed value. For example, the phrase "about 8" preferably refers to a value of 7.2 to 8.8 (inclusive of the endpoint). Where present, all ranges are inclusive and combinable. For example, when the range "1 to 5" is stated, the stated range should be interpreted as including ranges "1 to 4," "1 to 3," "1 to 2," "1 to 2 and 4 to 5," "1 to 3 and 5," "2 to 5," and so on. Furthermore, when a list of alternatives is provided positively, such a list can be interpreted as indicating that any alternatives can be excluded, for example, by the negative limitations in the claims. For example, when the range "1 to 5" is described, the described range can be interpreted as including the negative exclusion of any one of 1, 2, 3, 4 or 5; therefore, the description of "1 to 5" can be interpreted as "1 and 3 to 5" but excluding "2", or simplified to "excluding 2". In other words, any component, element, property or step that is expressly stated herein can be expressly excluded in the claims, whether such component, element, property or step is listed as an alternative or described independently.

[0031] As used herein, the terms "substantially," "substantially," and variations thereof are intended to indicate that the described feature is equal to or approximately equal to a value or description. Furthermore, "substantially similar" is intended to mean that two values ​​are equal or approximately equal. In some embodiments, "substantially similar" may mean values ​​that are within approximately 10% of each other, such as within approximately 5% or approximately 2%.

[0032] This disclosure provides glass compositions, methods of manufacturing them, and methods of using them. This disclosure also provides glass substrates or articles comprising such glass compositions, and devices comprising such glass compositions or glass substrates having such glass compositions. These glass compositions contain the components described herein, including high contents of Al₂O₃ and Y₂O₃. As described herein, it has been surprisingly found that such glass compositions, in addition to possessing the other desirable properties described herein, also provide high modulus and high fracture toughness.

[0033] In some embodiments, the substrate is optically transparent. Examples of substrates include, but are not limited to, flat or curved glass panels.

[0034] Unless otherwise expressly stated, the terms “glass articles” or “glass” as used herein shall be understood to include objects which are wholly or partially made of glass. Glass articles include monolithic substrates, or stacks of glass and glass, glass and non-glass materials, glass and crystalline materials, and glass and glass ceramics (including amorphous and crystalline phases).

[0035] Glass articles, such as glass panels, can be flat or curved, and are transparent or substantially transparent. As used herein, the term "transparent" is intended to mean that an article with a thickness of approximately 1 mm has a transmittance greater than about 85% in the visible light region of the spectrum (400 to 700 nm). For example, exemplary transparent glass panels may have a transmittance greater than about 85% in the visible light range, such as greater than about 90%, greater than about 95%, or greater than about 99%, including all ranges and subranges therebetween. According to various embodiments, glass articles may have a transmittance less than about 50% in the visible region, such as less than about 45%, less than about 40%, less than about 35%, less than about 30%, less than about 25%, or less than about 20%, including all ranges and subranges therebetween. In some embodiments, the exemplary glass panel may have a transmittance greater than about 50% in the ultraviolet (UV) region (100 to 400 nm), such as greater than about 55%, greater than about 60%, greater than about 65%, greater than about 70%, greater than about 75%, greater than about 80%, greater than about 85%, greater than about 90%, greater than about 95%, or greater than about 99%, including all ranges and subranges therebetween.

[0036] Exemplary glasses may include, but are not limited to: aluminosilicates, alkali metal aluminosilicates, borosilicates, alkali metal borosilicates, aluminoborosilicates, alkali metal aluminoborosilicates, and other suitable glasses. In some embodiments, glass articles may be mechanically strengthened by utilizing the mismatch in the coefficients of thermal expansion between different parts of the article to create regions of compressive stress and a central region exhibiting tensile stress. In some embodiments, glass articles may be thermally strengthened by heating the glass to a temperature above the glass transition point and then rapidly quenching it. In some other embodiments, glass articles may be chemically strengthened by ion exchange.

[0037] As used herein, the term "softening point" refers to the temperature at which the viscosity of a glass composition is 1 × 10⁷.6 poise.

[0038] As used herein, the term "annealing point" refers to the temperature at which the viscosity of a glass composition is 1 × 10¹³.18 poise.

[0039] As used herein, the terms “strain point” and “Tstrain” refer to the temperature at which the viscosity of the glass composition is 3 × 10¹⁴.68 poise.

[0040] The liquidus temperature (Tliq) of glass refers to the temperature (°C) above which no crystalline phase coexists with the glass in equilibrium. Liquidus viscosity is the viscosity of the glass at its liquidus temperature.

[0041] As used herein, the term "CTE" refers to the coefficient of thermal expansion of a glass composition over a temperature range from approximately room temperature (RT) to approximately 300°C.

[0042] Fracture toughness can be measured using methods known in the technical field to which this case pertains, such as using a chevron notch, short bar, notched beam, etc., according to ASTM C1421-10, "Standard Test Method for Determining Fracture Toughness of Advanced Ceramics at Ambient Temperature". The fracture toughness value (K1C) described in this disclosure refers to the value measured by the chevron-notched short bar (CNSB) method, which is disclosed in Reddy, KP R et al., “Fracture Toughness Measurement of Glass and Ceramic Materials Using Chevron-Notched Specimens”, J. Am. Ceram. Soc., 71 [6], C-310-C-313 (1988). The difference is that it uses the closed-form expressions for crack-mouth displacement and stress intensity factors for chevron-notched short bar and short rod specimens based on experimental compliance measurements” by Bubsey, RT et al., NASA Technical Memorandum 83796, pp. Use Formula 5 from 1-30 (October 1992) to calculate Y*m.

[0043] The Young's modulus, shear modulus, and Passon's ratio described in this disclosure refer to values ​​(converted to GPa) measured using a general type of resonant ultrasound spectroscopy technique as described in ASTM E2001-13, entitled "Standard Guide for Resonant Ultrasound Spectroscopy for Defect Detection in Both Metallic and Non-metallic Parts".

[0044] The stress optical coefficient (SOC) value can be measured using Procedure C (glass disk method) as described in ASTM standard C770-16, entitled "Standard Test Method for Measurement of Glass Stress-Optical Coefficient".

[0045] In the embodiments of the glass composition described herein, unless otherwise specified, the concentration of the constituent components (e.g., SiO2, Al2O3, etc.) is specified in mole percentage (moles %) of oxides.

[0046] When used to describe the concentration and / or absence of a particular constituent component in a glass composition, the terms "free" and "substantially free" mean that the constituent component was not intentionally added to the glass composition. However, as a contaminant or impurity, a glass composition may contain trace amounts of the constituent component in amounts less than 0.01 mol%.

[0047] U.S. Patent Application No. 2014 / 0141226 discloses an ion-exchangeable glass with high hardness and high elastic modulus, and describes a sodium aluminosilicate glass containing a wide range of yttrium oxide exhibiting phase separation or devitrification. For example, according to the ternary phase diagram shown in Figure 1 of U.S. Patent Application No. 2014 / 0141226, phase separation occurs when the Al₂O₃ content is in the range of about 15 mol% to about 22 mol% and the yttrium oxide content is above about 7 mol%; devitrification occurs when the yttrium oxide content is above about 22.5 mol%. U.S. Patent Application No. 2014 / 0141226 provides a glass composition containing up to 7 mol% Y₂O₃, thus avoiding such devitrification.

[0048] U.S. Patent Application No. 2018 / 0022635 discloses glass compositions and glass articles having high breaking toughness, comprising one or more metal oxides selected from the group consisting of La₂O₃, BaO, Ta₂O₅, Y₂O₃, and HfO₂, particularly two or more metal oxides. In such glass articles, the Al₂O₃ content ranges from about 1 mol% to about 15 mol%.

[0049] This disclosure provides glass compositions or glass substrates containing the components described herein, including high contents of Al₂O₃ and Y₂O₃. Surprisingly, such glass compositions provide glass articles with good quality and desirable properties, including high modulus and high breaking toughness.

[0050] According to some embodiments, the glass substrate comprises: SiO2 of approximately 45 mol% to approximately 70 mol%; Al₂O₃: approximately 15 mol% to approximately 30 mol% Y₂O₃ of approximately 7 mol% to approximately 20 mol%; and La2O3, from 0 mol% to approximately 9 mol%, depending on the situation.

[0051] In some embodiments, the glass substrate comprises about 27 mol% to about 43 mol% of R2O3, wherein the R2O3 comprises Al2O3, Y2O3, and La2O3 in total. Examples of suitable ranges include, but are not limited to, about 28 mol% to about 40 mol%, about 30 mol% to about 40 mol%, or about 32 mol% to about 38 mol%. In some embodiments, the glass substrate has a molar ratio of [(Y2O3 + La2O3) / Al2O3] in the range of about 0.3 to about 1.7, for example, from about 0.5 to about 1.7 or from about 1 to about 1.5.

[0052] In the glass substrate embodiments described herein, SiO2 is the largest component of the composition and, therefore, the main component of the glass network. SiO2 can be used to obtain the desired liquid phase viscosity while offsetting the amount of Al2O3 added to the composition.

[0053] The glass substrate contains any suitable range of SiO2. Examples of suitable ranges include, but are not limited to: about 50 mol% to about 70 mol%, about 52 mol% to about 70 mol%, about 52 mol% to about 66 mol%, about 54 mol% to about 66 mol%, or about 60 mol% to about 66 mol%.

[0054] The glass substrate described herein further comprises a relatively high content of Al2O3. In some embodiments, the Al2O3 content is equal to or greater than 15 mol%. Examples of suitable ranges of Al2O3 include, but are not limited to: about 16 mol% to about 30 mol%, about 17 mol% to about 30 mol%, about 18 mol% to about 30 mol%, about 18 mol% to about 28 mol%, or about 18 mol% to about 25 mol%.

[0055] To achieve high modulus and high fracture toughness, the glass substrate in the embodiments described herein also contains Y2O3, La2O3, or a combination thereof.

[0056] In some embodiments, the content of Y₂O₃ is equal to or greater than 7 mol%. Examples of suitable ranges for Y₂O₃ include, but are not limited to: about 8 mol% to about 20 mol%, about 9 mol% to about 20 mol%, about 7 mol% to about 16 mol%, about 7 mol% to about 15 mol%, about 8 mol% to about 16 mol%, or about 10 mol% to about 16 mol.

[0057] La₂O₃ may be present, depending on the situation. Examples of suitable ranges for La₂O₃ include, but are not limited to: about 0.1 mol% to about 9 mol%, about 1 mol% to about 9 mol%, about 2 mol% to about 9 mol%, or about 3 mol% to about 9 mol%. When the glass substrate contains La₂O₃, such glass substrate does not contain B₂O₃.

[0058] In some other embodiments, the glass substrate further comprises 0 mol% to about 6 mol% of B₂O₃, for example, 0.1 mol% to about 6 mol% of B₂O₃ or 0.1 mol% to about 1 mol% of B₂O₃. When B₂O₃ is added, the glass substrate is substantially free of La₂O₃. B₂O₃ and La₂O₃ are not added together to the same formulation.

[0059] The glass substrate may further contain 0 mol% to about 6 mol% of MgO, for example, 0 to about 5 mol%, 0 to about 4 mol%, 0 to about 3 mol%, about 0.1% to about 5 mol%, about 0.1% to about 4 mol%, about 0.1% to about 3 mol%.

[0060] The glass substrate may further comprise 0 mol% to about 12 mol% of alkali metal oxides, such as Li₂O, Na₂O, K₂O, or combinations thereof. Examples of suitable ranges for Li₂O, Na₂O, K₂O, or combinations thereof include, but are not limited to: 0.1 mol% to about 12 mol%, 0.1 mol% to about 10 mol%, 0.1 mol% to about 8 mol%, and 0.1 mol% to about 5 mol%. In some embodiments, the total content of Li₂O, Na₂O, and K₂O is less than 13%. In some embodiments, the glass substrate is substantially free of alkali metal oxides.

[0061] In some embodiments, the molar percentage difference of (Al₂O₃–R₂O–RO) is in the range of about 7 to about 22, for example, about 7.1 to about 21.6, about 10 to about 20, or about 15 to about 20. R₂O comprises an alkali metal oxide selected from the group consisting of Na₂O, K₂O, and any combination thereof. RO comprises an alkaline earth metal oxide selected from the group consisting of MgO, SrO, BaO, and any combination thereof. The glass substrate is substantially free of CaO.

[0062] In some embodiments, the glass substrate is substantially free of CaO, Eu2O3, Nb2O3, Si3N4, WO3, ZrO4 and TiO2, except for CaO.

[0063] According to some embodiments, this disclosure provides a glass substrate that is substantially composed of the following components: SiO2 of approximately 45 mol% to approximately 70 mol%; Al₂O₃: approximately 15 mol% to approximately 30 mol% Y₂O₃: approximately 7 mol% to approximately 20 mol% 0 mol% to approximately 9 mol% of La2O3; 0 mol% to about 6 mol% of MgO; and Alkali metal oxides of 0 mol% to about 12 mol%, selected from the group consisting of Li₂O, Na₂O, K₂O and combinations thereof.

[0064] The glass substrate contains approximately 27 moles to approximately 43 moles of R₂O₃, wherein the R₂O₃ comprises Al₂O₃, Y₂O₃, and La₂O₃. The glass substrate has a molar ratio of [(Y₂O₃ + La₂O₃) / Al₂O₃] ranging from approximately 0.3 to approximately 1.7. As described herein, La₂O₃, B₂O₃, MgO, and alkali metal oxides (such as Na₂O and K₂O) are present as appropriate. La₂O₃ and B₂O₃ do not coexist in the glass substrate.

[0065] According to some embodiments, this disclosure provides a glass substrate that is substantially composed of the following components: SiO2 of approximately 45 mol% to approximately 70 mol%; Al₂O₃ of approximately 15 mol% to approximately 30 mol%; and Y₂O₃: approximately 7 mol% to approximately 20 mol%.

[0066] The glass substrates provided in this disclosure have favorable properties such as ease of handling and excellent mechanical properties including high modulus and high breaking toughness. In some embodiments, the breaking toughness (KIC) of the glass substrate is in the range of about 0.87 MPa.m0.5 to about 2 MPa.m0.5, for example, about 0.87 MPa.m0.5 to about 1.5 MPa.m0.5, about 0.87 MPa.m0.5 to about 1.2 MPa.m0.5, or 0.87 to about 1.07 MPa.m0.5.

[0067] In some embodiments, glass articles may have the following breaking toughness values: about 0.87 MPa*m0.5, about 0.9 MPa*m0.5, about 1 MPa*m0.5, about 1.1 MPa*m0.5, about 1.2 MPa*m0.5, about 1.3 MPa*m0.5, about 1.4 MPa*m0.5, about 1.5 MPa*m0.5, about 1.6 MPa*m0.5, about 1.8 MPa*m0.5, about 2 MPa*m0.5, or any range between the specified values.

[0068] The glass substrate also provides Young's modulus in the range of about 100 GPa to about 140 GPa, for example, about 100 GPa to about 130 GPa, about 100 GPa to about 120 GPa, about 105 GPa to about 120 GPa, and about 110 GPa to about 120 GPa.

[0069] The glass substrate is also provided with shear modulus in the following ranges: about 30 GPa to about 60 GPa, about 35 GPa to about 50 GPa, about 39 GPa to about 50 GPa, or about 40 GPa to about 50 GPa.

[0070] In another embodiment, this disclosure also provides methods for manufacturing and using the glass substrate described herein. Glass articles can be prepared by methods involving melting and mixing individual oxides. However, in some embodiments, the "confusion principle" can be used to maximize mixing entropy, for example, to suppress crystallization.

[0071] The glass substrate provided in this disclosure has an amorphous structure that provides such fracture toughness and high modulus. However, in some other embodiments, the glass substrate may be made into a crystalline structure to have further improved modulus and fracture toughness.

[0072] This disclosure also provides glass articles (or components) that include such glass substrates, and devices that include or have glass substrates.

[0073] Examples of glass articles include, but are not limited to: panels, substrates, information recording discs or memory discs, covers, backplates, and any other components used in electronic devices. For example, in some embodiments, a glass composition or glass substrate may be used as a substrate for a memory disc or as a substrate for a cover or backplate in a display device.

[0074] In addition to high Young's modulus and high fracture toughness, the glass substrate disclosed herein also exhibits high hardness and a relatively low softening point at the corresponding high strain / annealing point. The Vickers hardness (VHN, 200 g load) ranges from 700 to 850, for example, 750 to 850, or 767 to 818. At the softening point of 890 to 1050°C, the corresponding strain / annealing point (Δsoftening-strain Pt) ranges from 190 to 300, for example, 190 to 270. A relatively low softening point is observed at the corresponding high strain / annealing point.

[0075] Glasses with these mechanical properties are needed in a wide range of applications, from memory discs requiring high Young's modulus (stiffness) to display applications. For displays, a high Young's modulus minimizes the effects of thin-film stress, while high strain and annealing point minimize stress and low-temperature relaxation—both critical when the glass undergoes subsequent processing during thin-film transistor deposition. For both applications, high breaking toughness of the glass leads to increased strength for a given flaw size population. The challenges of these components are long-standing and have been addressed in the past using advantageous mechanical properties. This disclosure provides unique glass substrates designed to achieve the high modulus, high breaking toughness, and high hardness described herein by utilizing the high cationic field strength of a network modifier.

[0076] The glass substrate has a relatively high density, for example, in the range of 2.8 g / cm³ to 3.9 g / cm³. The glass substrate also has a relatively high refractive index (up to 1.708).

[0077] The glass substrate disclosed herein has a low stress optical coefficient (SOC) below about 4 brewsters, for example, in the range of about 1 brewster to about 4 brewsters. As will be understood by those skilled in the art to which this application pertains, SOC is related to the birefringence of the glass. The glass substrate may have an SOC of about 1 brewster to about 3 brewsters or about 1.5 brewsters to about 2.5 brewsters. In some embodiments, the SOC may be as low as about 1.7.

[0078] In some embodiments, the glass substrate has a coefficient of thermal expansion (CTE) (22 to 300°C) in the following ranges: about 10 x 10⁻⁷ / ºC to about 60 x 10⁻⁷ / ºC, for example, in the range of about 30 x 10⁻⁷ / ºC to about 56 x 10⁻⁷ / ºC, or in the range of about 35 x 10⁻⁷ / ºC to about 55 x 10⁻⁷ / ºC.

[0079] Example

[0080] The following examples illustrate the methods and results based on the disclosed subject matter. These examples are not intended to include all embodiments of the subject matter disclosed herein, but are used to illustrate representative methods and results. These examples are not intended to exclude equivalents and variations of the disclosure that would be obvious to those skilled in the art to which this application pertains.

[0081] Efforts have been made to ensure the accuracy of figures (e.g., content, temperature, etc.), but some errors and biases should still be considered. Unless otherwise specified, temperatures are in °C or ambient temperature, and pressures are at or near atmospheric pressure. The components themselves are given as molar percentages based on oxides and have been normalized to 100%. Reaction conditions can vary and be combined in many ways, such as component concentrations, temperatures, pressures, and other ranges and conditions that can be used to optimize the purity and yield of the products obtained from the method. Such process conditions can be optimized with only reasonable and routine experiments.

[0082] The glass properties listed in Tables 1 through 7 were determined using standard techniques in the glass industry. Therefore, the coefficient of linear thermal expansion (CTE) over the temperature range of 25°C to 300°C is expressed as x 10⁻⁷ / ºC, and the annealing point is expressed in ºC. The CTE was determined according to ASTM E228. Unless otherwise specified, the annealing point was determined using the fiber elongation technique according to ASTM C336. The density was measured in grams per cubic centimeter using the Archimedes method (ASTM C693). The melting temperature (defined as the temperature at which the glass melt exhibits a viscosity of 200 poise) was calculated using the Fulcher equation, which agrees with the high-temperature viscosity data measured by the rotating cylinders viscometry method (ASTM C965-81).

[0083] The standard gradient boat liquidus method (ASTM C829-81) is used to measure the liquidus temperature of glass, expressed in °C. This involves placing glass shards in a platinum boat, placing the boat in a furnace with a gradient temperature zone, heating the boat for 24 hours within a suitable temperature range, and determining the highest temperature at which crystals appear inside the glass using microscopic examination. More specifically, the glass sample is removed entirely from the Pt boat and examined using polarized light microscopy to determine the location and nature of crystals forming against the platinum-air interface and within the sample. Since the furnace gradient is well-known, the temperature-to-location comparison can be easily estimated with an error within 5 to 10 °C. The temperature at which crystals are observed within the sample is taken as the liquidus (for the corresponding test period). Sometimes, the test is performed for a longer time (e.g., 72 hours) to observe slower-growing phases. The liquidus viscosity, expressed in poises, is determined from the liquidus temperature and the coefficients of the Fulcher equation.

[0084] The Young's modulus, expressed in GPa, was determined using the general type of resonance ultrasonic spectroscopy technique described in ASTM E1875-00e1.

[0085] Example glasses are shown in Tables 1 through 7. Commercial sand was used as the silica source to prepare the example glasses, which were ground to ensure that 90% by weight of the commercial sand passed through a standard US 100-mesh sieve. Alumina was used as the alumina source, and periclase was used as the MgO source. Depending on the formulation, Y₂O₃, La₂O₃, and B₂O₃ may also be used. The raw materials were thoroughly mixed and double-melted, and stirred at 1600 to 1650°C for several hours to ensure homogeneity. The resulting glass cake was annealed at or near its annealing point, and then subjected to various experimental methods to determine its physical, viscous, and liquidus properties.

[0086] These methods are not unique, and standard methods well known to those skilled in the art to which this case pertains can be used to prepare the glasses listed in Tables 1 to 7. Such methods include continuous melting processes, such as those performed in continuous melting processes, wherein the melter used in the continuous melting process is heated by gas, electricity, or a combination thereof.

[0087] Raw materials suitable for producing exemplary glass include commercially available sand as a source of SiO2; alumina, aluminum hydroxide, hydrated forms of alumina, and various aluminosilicates, nitrates, and halides as sources of Al2O3; boric acid, anhydrous boric acid, and boron oxide as sources of B2O3; and periclase, magnesium oxide, magnesium carbonate, magnesium hydroxide, and various forms of magnesium silicate, aluminosilicates, nitrates, and halides as sources of MgO. If chemical clarifying agents are required, tin may be added in the form of SnO2, in the form of a mixed oxide with another major glass component (e.g., CaSnO3), or under oxidizing conditions in the form of SnO, tin oxalate, tin halides, or other tin compounds known to those skilled in the art to which this application pertains.

[0088] The glass may also contain SnO2 as a clarifying agent. Other chemical clarifying agents can also be used to obtain glass of sufficient quality for TFT substrate applications. For example, the exemplary glass may use any or a combination of As2O3, Sb2O3, CeO2, Fe2O3, and halides as appropriate additives to promote clarification, and any of these substances may be used in combination with the SnO2 chemical clarifying agent shown in the examples. As2O3 and Sb2O3 are generally considered hazardous substances, and waste streams, such as those that may be generated during glass manufacturing or TFT panel processing, need to be controlled. Therefore, whether alone or in combination, it is desirable to limit the concentration of As2O3 and Sb2O3 to no more than 0.005 moles.

[0089] Besides incorporating elements into the example glass in appropriate amounts, the properties of the final glass can be finely adjusted by introducing low-level contaminants from the raw materials, by the high-temperature corrosion of refractory materials and precious metals during the manufacturing process, or by introducing them in small amounts to ensure that almost all stable elements in the periodic table are present in the glass at some level. For example, zirconium can be introduced as a contaminant through interaction with zirconium-rich refractory materials. As another example, platinum and rhodium can be introduced through interaction with precious metals. As yet another example, iron can be introduced into the raw materials as an impurity, or added in appropriate amounts to enhance control over gaseous inclusions. As a further example, manganese can be introduced to control color or enhance control over gaseous inclusions.

[0090] As a further example, alkali metals can exist as impurity components at a combined concentration of Li₂O, Na₂O, and K₂O at a level of up to about 0.1 mol%.

[0091] Hydrogen inevitably exists in the form of hydroxide anions, OH⁻, which can be determined using standard infrared spectroscopy. Dissolved hydroxide ions significantly and non-linearly affect the annealing point of the exemplary glass, and therefore, to obtain the desired annealing point, it may be necessary to adjust the concentration of the main oxide component to compensate. The concentration of hydroxide ions can be controlled to some extent by selecting the raw materials or the melting system. For example, boric acid is a major source of hydroxide, and replacing boric acid with boron oxide is a useful means of controlling the hydroxide concentration in the final glass. The same reasoning applies to other potential raw materials containing hydroxide ions, hydrates, or compounds containing physically or chemically adsorbed water molecules. If a burner is used in the melting process, hydroxide ions can also be introduced through combustion products from the combustion of natural gas and related hydrocarbons, and therefore it may be necessary to transfer the energy used in melting from the burner to the electrodes to compensate. Alternatively, an iterative process of adjusting the main oxide component can be used to compensate for the detrimental effects of dissolved hydroxide ions.

[0092] Sulfur is commonly found in natural gas and is also an impurity component in many carbonate, nitrate, halide, and oxide feedstocks. Sulfur can be a troublesome source of gaseous inclusions in the form of SO2. The tendency to form SO2-rich defects can be significantly controlled by managing the sulfur content in the feedstock and by incorporating low amounts of relatively reduced polyvalent cations into the glass matrix. While not wishing to be bound by theory, SO2-rich gaseous inclusions appear to be primarily generated through the reduction of sulfates (SO4) dissolved in the glass.

[0093] The increased barium concentration in the example glass appears to increase sulfur retention in the glass during the early stages of melting; however, as mentioned above, barium is required to achieve a low liquidus temperature and thus a high T35k-Tliq and high liquidus viscosity. Controlling the sulfur content in the feedstock to a low level is a useful method to reduce dissolved sulfur (potentially sulfate) in the glass. Specifically, the sulfur content in the batch is preferably less than 200 ppm (by weight), and more preferably less than 100 ppm (by weight).

[0094] Reduced multivalent ions can also be used to control the tendency of exemplary glasses to form SO2 bubbles (blister). While not wishing to be bound by theory, these elements act as potential electron donors, suppressing the electromotive force of sulfate reduction. Sulfate reduction can be represented by a half-reaction, such as... SO4 = SO2 + O2 + 2e- Where e- represents an electron. The equilibrium constant for this half-reaction is: Keq = [SO2 ][O2 ][e- ]2 / [SO4 = ] The parentheses indicate chemical reactivity. Ideally, the reaction should be forced to produce sulfate from SO2, O2, and 2e-. Adding nitrates, peroxides, or other oxygen-rich feedstocks may be helpful, but they may also prevent sulfate reduction in the early stages of melting, potentially negating any initial benefits. SO2 has very low solubility in most glasses, making its addition to the glass melting process impractical. Electrons can be "added" through the reduction of polyvalent ions. For example, a suitable electron-donating half-reaction for ferrous iron (Fe2+) can be represented as: 2Fe²⁺ → 2Fe³⁺ + 2e⁻

[0095] This "activity" of electrons can force the sulfate reduction reaction to shift to the left, thereby stabilizing SO42- in the glass. Suitable reducing polyvalent ions include, but are not limited to: Fe2+, Mn2+, Sn2+, Sb3+, As3+, V3+, Ti3+, and others familiar to those skilled in the art to which this application pertains. In each case, minimizing the concentration of these components may be important to avoid adverse effects on the glass color, or, in the case of As and Sb, to avoid adding such components at sufficiently high levels that would complicate waste management in end-user processes.

[0096] In addition to the primary oxide components and the aforementioned minor components or impurities of the exemplary glass, various amounts of halides may be present. These halides can be introduced as contaminants through the selection of raw materials or added as appropriate components to eliminate gaseous inclusions in the glass. As a clarifying agent, about 0.4 moles or less of halides may be incorporated, although it is generally desirable to use even lower amounts if possible to avoid corrosion of exhaust gas treatment equipment. In some embodiments, the concentration of each individual halide element is less than about 200 ppm (by weight), or less than about 800 ppm (by weight) for the sum of all halide elements.

[0097] Table 1 shows the composition of Experimental Examples 1 to 5 (“Experimental Examples 1 to 5”). Table 2 shows the composition of Experimental Examples 6 to 10 (“Experimental Examples 6 to 10”). Table 3 shows the composition of Experimental Examples 11 to 16 (“Experimental Examples 11 to 16”). Table 4 shows the composition of Experimental Examples 17 to 22 (“Experimental Examples 17 to 22”). Table 5 shows the composition of Experimental Examples 23 to 28 (“Experimental Examples 23 to 28”). Table 6 shows the composition of Experimental Examples 29 to 34 (“Experimental Examples 29 to 34”). Table 7 shows the composition of Experimental Examples 35 to 42 (“Experimental Examples 35 to 42”).

[0098] The property data (including softening point, annealing point, Young's modulus, shear modulus, Pascal's ratio, breaking toughness, and hardness) of Examples 1 to 42 are listed in Tables 1 to 7. As can be seen in Tables 1 to 7, the example glasses have good properties such as high modulus and high breaking toughness, which makes them suitable for a variety of applications, including, but not limited to, memory discs and display applications (such as AMLCD substrate applications).

[0099] Please refer to Figure 1. The temperature difference between the softening point and strain point of these glasses is relatively small relative to their softening point. Data for these glass substrates are also compared with those for ordinary borosilicate glass, fused silica, and soda lime compositions. The glass compositions provided in this disclosure also offer processing advantages compared to ordinary glass.

[0100] Table 1 Experimental Example 1 Experimental Example 2 Experimental Example 3 Experiment Example 4 Experimental Example 5 Analysis of mole% SiO2 65.2 65.5 64.9 63.7 65.0 Al2 O3 20.0 19.6 20.0 19.7 17.0 B2 O3 Li2 O Na2 O MgO Y2 O3 13.7 11.8 10.1 15.5 14.8 La2 O3 1.0 3.0 4.9 1.0 3.1 Total 99.9 99.9 99.9 99.9 99.9 Al2 O3 - R2 O - RO 20.0 19.6 20.0 19.7 17.0 R2 O3 34.7 34.5 35.0 36.2 34.9 Density (g / cm3) 3.265 3.331 3.384 3.303 3.468 Mole volume (cm3 / mole) 28.73 28.80 29.06 29.30 28.84 Strain point (°C), by BBV 841 836 830 845 839 Annealing point (°C), by BBV 883 877 871 884 879 Softening point (°C), by PPV 1051 1043 1037 1047 1041 Δ(Softening Pt - Strain Pt) 209 207 206 202 202 Liquidus (°C): Test duration (hours) 72 72 72 72 72 Liquidus (°C) - Air 1355 1320 1295 1400 1430 Liquidus (°C) - Internal 1355 1315 1290 1400 1430 Liquidus (°C) - Platinum 1360 1315 1290 1400 1430 Liquid Phase unknown unknown unknown unknown unknown Stress optical coefficient (nm / MPa / cm) 2.264 2.212 2.156 2.209 2.066 Refractive index at 589.3 1.644 1.644 1.649 1.648 1.654 E (Young's Modulus, Mpsi) - RUS 15.9 15.7 15.2 16.1 16.0 G (shear modulus, Mpsi) - RUS 6.28 6.21 6.05 6.35 6.30 Passon's Value - RUS 0.268 0.262 0.267 0.267 0.271 E (Young's Modulus, GPa) - RUS 110 108 105 111 110 G (shear modulus, GPa) - RUS 43.3 42.8 41.7 43.8 43.4

[0101] Table 2 Experimental Example 6 Experimental Example 7 Experimental Example 8 Experimental Example 9 Experimental Example 10 Analysis of mole% SiO2 63.6 63.2 63.5 63.6 63.6 Al2O3 19.7 18.1 15.8 13.6 11.9 B2O3 Li2O 1.0 2.0 3.0 4.0 4.8 Na2O MgO Y2O3 14.6 14.6 14.6 14.8 14.6 La2O3 1.0 2.0 3.1 3.9 5.0 Total 99.9 99.9 99.9 99.9 99.9 Al2O3 - R2O - RO 18.7 16.1 12.8 9.7 7.1 R2O3 35.3 34.7 33.5 32.3 31.4 Density (g / cm3) 3.304 3.390 3.460 3.535 3.621 Mole volume (cm3 / mole) 28.71 28.49 28.38 28.14 27.91 Strain point (°C), by BBV 817 796 778 759 746 Annealing point (°C), by BBV 858 837 820 800 787 Softening point (°C), by PPV 1032 1010 982 964 949 Δ(Softening Pt - Strain Pt) 215 214 203 205 203 Liquidus (°C): Test duration (hours) 72 72 72 72 72 Liquidus (°C) - Air 1395 1430 >1375 >1345 >1330 Liquidus (°C) - Internal 1395 1430 >1375 >1345 >1330 Liquidus (°C) - Platinum 1405 1430 >1375 >1345 >1330 Liquid Phase unknown unknown unknown unknown Stress optical coefficient (nm / MPa / cm) 2.170 2.114 2.060 1.987 1.896 Refractive index at 589.3 1.644 1.653 1.660 1.669 1.678 E (Young's Modulus, Mpsi) - RUS 16.2 16.3 16.1 16.2 16.3 G (shear modulus, Mpsi) - RUS 6.41 6.43 6.38 6.40 6.38 Passon's Value - RUS 0.264 0.266 0.262 0.267 0.275 E (Young's Modulus, GPa) - RUS 112 112 111 112 112 G (shear modulus, GPa) - RUS 44.2 44.3 44.0 44.1 44.0 Failure toughness (MPa * sqrt(m)) 0.95 0.95 Standard deviation 0.02 0.02

[0102] Table 3 Experimental Example 11 Experimental Example 12 Experimental Example 13 Experimental Example 14 Experimental Example 15 Experimental Example 16 Analysis of mole% SiO2 63.75 61.41 59.68 57.84 55.86 53.94 Al2 O3 19.69 19.7 19.69 19.8 19.69 19.7 B2 O3 Li2 O 1.94 4.02 5.8 7.89 9.88 11.85 Na2 O MgO Y2 O3 14.43 14.68 14.64 14.27 14.39 14.33 La2 O3 Total 99.81 99.81 99.81 99.8 99.82 99.82 Al2O3 - R2O - RO 17.8 15.7 13.9 11.9 9.8 7.9 R2 O3 34.1 34.4 34.3 34.1 34.1 34.0 Density (g / cm3) 3.258 3.265 3.231 3.232 3.231 3.233 Mole volume (cm3 / mole) 28.14 28.01 28.12 27.74 27.61 27.38 Expansion (10⁻⁷ / °C) 48 50 45 Strain point (°C), by BBV 801 773 751 730 710 695 Annealing point (°C), by BBV 842 815 792 769 749 733 Softening point (°C), by PPV 1011 983 953 935 911 892 Δ(Softening Pt - Strain Pt) 210 210 202 205 201 197 Liquidus (°C): Test duration (hours) 72 72 72 72 72 72 Liquidus (°C) - Air 1335 1405 1405 1410 1415 1415 Liquidus (°C) - Internal 1335 1410 1405 1410 1415 1420 Liquidus (°C) - Platinum 1335 1420 1405 1410 1415 1425 Liquid Phase unknown unknown unknown unknown lithium yttrium silicate Yttrium aluminum oxide Stress optical coefficient (nm / MPa / cm) 2.225 2.202 2.168 2.138 2.113 Refractive index at 589.3 1.633 1.637 1.639 1.641 1.643 1.644 E (Young's Modulus, Mpsi) - RUS 16.1 16.3 16.3 16.4 16.3 16.4 G (shear modulus, Mpsi) - RUS 6.39 6.45 6.42 6.47 6.45 6.46 Passon's Value - RUS 0.262 0.262 0.271 0.270 0.263 0.265 E (Young's Modulus, GPa) - RUS 111 112 113 113 112 113 G (shear modulus, GPa) - RUS 44.1 44.5 44.3 44.6 44.5 44.5 Failure toughness (MPa * sqrt(m)) 1.04 0.94 0.96 0.97 0.94 0.91 Standard deviation 0.08 0.02 0.02 0.02 0.03 0.02 Hardness - Vickers 200 g load 807 818 Hardness - Standard Deviation 15 twenty two

[0103] Table 4 Experimental Example 17 Experimental Example 18 Experimental Example 19 Experimental Example 20 Experimental Example 21 Experiment Example 22 Analysis of mole% SiO2 61.49 57.49 54.39 59.4 58.6 57.7 Al2O3 21.8 23.65 25.18 19.0 18.7 18.8 B2 O3 Li2 O 1.92 3.92 5.79 5.9 6.9 7.9 Na2 O MgO Y2 O3 14.57 14.73 14.42 15.4 15.6 15.4 La2 O3 Total 99.78 99.​​​​​​​​​​​​​​​​​13.1 11.8 10.9 R2 O3 36.4 38.4 39.6 34.5 34.3 34.2 Density (g / cm3) 3.239 3.237 3.246 3.284 3.289 3.28 Mole volume (cm3 / mole) 28.64 28.80 28.59 27.97 27.87 27.76 Expansion (10⁻⁷ / °C) 48 51 45 Strain point (°C), by BBV 802 773 753 749 739 731 Annealing point (°C), by BBV 843 814 793 789 779 770 Softening point (°C), by PPV 1010 978 955 956 938 932 Δ(Softening Pt - Strain Pt) 209 205 202 206 200 202 Liquidus (°C): Test duration (hours) 72 72 72 72 72 72 Liquidus (°C) - Air 1410 1400 1380 1440 1430 1430 Liquidus (°C) - Internal 1410 1400 1380 1440 1430 1435 Liquidus (°C) - Platinum 1410 1400 1375 1440 1430 1440 liquid phase unknown unknown unknown unknown unknown unknown Stress optical coefficient (nm / MPa / cm) 2.231 2.174 2.147 2.160 2.145 2.131 Refractive index at 589.3 1.640 1.642 1.645 1.646 1.647 1.649 E (Young's Modulus, Mpsi) - RUS 16.6 16.8 16.7 16.4 16.4 16.5 G (shear modulus, Mpsi) - RUS 6.55 6.60 6.62 6.49 6.47 6.48 Passon's Value - RUS 0.264 0.269 0.261 0.265 0.267 0.274 E (Young's Modulus, GPa) - RUS 114 115 115 113 113 114 G (shear modulus, GPa) - RUS 45.2 45.5 45.6 44.7 44.6 44.7 Failure toughness (MPa * sqrt(m)) 0.97 0.95 0.96 0.94 0.95 0.95 Standard deviation 0.02 0.03 0.03 0.02 0.02 0.03 Hardness - Vickers 200 g load 803 Hardness - Standard Deviation twenty one

[0104] Table 5 Experimental Example 23 Experimental Example 24 Experimental Example 25 Experimental Example 26 Experimental Example 27 Experimental Example 28 Analysis of mole% SiO2 61.0 64.7 65.0 62.08 60.58 59.68 Al2O3 19.9 20.1 20.0 20.38 20.2 19.7 B2O3 2.01 4 5.94 Li2O 2.0 4.0 2.01 2 1.98 Na2O MgO 4.0 2.0 4.0 2.06 2.01 1.91 Y2O3 14.9 11.1 6.9 11.3 11.06 10.64 La2O3 Total 99.8 99.8 99.9 99.84 99.85 99.85 Al2O3 - R2O - RO 16.0 16.0 12.0 16.3 16.2 15.8 R2O3 34.8 31.1 26.9 31.7 31.3 30.3 Density (g / cm3) 3.28 3.033 2.837 3.042 3.039 3.008 Mole volume (cm3 / mole) 28.16 28.30 27.44 28.45 28.39 28.45 Expansion (10⁻⁷ / °C) 45 38 41 41 42 Strain point (°C), by fiber elongation 788 745 770 828 786 Annealing point (°C), by fiber elongation 831 790 813 869 828 Softening point (°C), determined by fiber elongation 1006 976 1021 1034 996 Strain point (°C), by BBV 822 787 745 814 828 786 Annealing point (°C), by BBV 864 831 789 856 869 828 Softening point (°C), by PPV 1036 981 1010 1021 1034 996 Δ(Softening Pt - Strain Pt) 214 195 266 207 206 210 Liquidus (°C): Test duration (hours) 72 72 72 72 72 72 Liquidus (°C) - Air 1375 1340 1400 1365 1325 1360 Liquidus (°C) - Internal 1375 1345 1390 1350 1320 1330 Liquidus (°C) - Platinum 1375 1335 1390 1355 1325 1330 Liquid Phase unknown Primal pyroxene Primal pyroxene Andalusite Andalusite Andalusite Stress optical coefficient (nm / MPa / cm) Refractive index at 589.3 2.173 2.399 2.559 2.251 2.282 2.277 E (Young's Modulus, Mpsi) - RUS 1.645 1.608 1.580 1.641 1.633 1.632 G (shear modulus, Mpsi) - RUS 16.6 17.4 15.0 16.1 15.8 15.8 Passon's Value - RUS 6.52 6.78 5.99 6.38 6.25 6.30 E (Young's Modulus, GPa) - RUS 0.271 0.281 0.250 0.261 0.264 0.255 G (shear modulus, GPa) - RUS 114 120 103 111 109 109 Failure toughness (MPa * sqrt(m)) 45.0 46.7 41.3 44.0 43.1 43.4 Standard deviation 1.02 0.97 0.95 0.95 0.90 0.96 Hardness - Vickers 200 g load 0.03 0.03 0.03 0.02 0.03 0.03 Hardness - Standard Deviation 767 34

[0105] Table 6 Experimental Example 29 Experimental Example 30 Experimental Example 31 Experimental Example 32 Experimental Example 33 Experimental Example 34 Analysis of mole% SiO2 64.68 61.76 59.24 59.7 57.7 54.0 Al2 O3 19.31 19.9 19.98 19.9 20.0 20.0 B2 O3 1.97 3.96 5.98 Li2 O Na2 O 1.7 1.71 1.77 5.6 7.5 11.2 MgO 1.85 1.89 1.97 Y2 O3 10.36 10.65 10.94 14.7 14.7 14.7 La2 O3 Total 99.87 99.87 99.88 99.9 99.9 99.8 Al2O3 - R2O - RO 15.8 16.3 16.2 14.4 12.5 8.8 R2 O3 29.7 30.6 30.9 34.6 34.6 34.6 Density (g / cm3) 3.057 3.008 3.012 3.216 3.219 3.195 Mole volume (cm3 / mole) 27.88 28.63 28.82 28.90 28.87 29.11 Expansion (10⁻⁷ / °C) 43 42 42 Strain point (°C), by fiber elongation 816 768 801 Annealing point (°C), by fiber elongation 858 808 842 Softening point (°C), determined by fiber elongation 1023 971 1003 Strain point (°C), by BBV 816 768 801 802 793 784 Annealing point (°C), by BBV 858 808 842 843 836 826 Softening point (°C), by PPV 1023 971 1003 1022 1013 990 Δ(Softening Pt - Strain Pt) 207 203 202 220 220 206 Liquidus (°C): Test duration (hours) 72 72 72 72 72 72 Liquidus (°C) - Air 1350 1350 1330 1465 1470 1560 Liquidus (°C) - Internal 1345 1345 1330 1470 1470 1570 Liquidus (°C) - Platinum 1350 1350 1330 1470 1470 1570 Liquid Phase Andalusite Andalusite Andalusite unknown unknown unknown Stress optical coefficient (nm / MPa / cm) 2.306 2.216 2.240 2.316 2.294 2.221 Refractive index at 589.3 1.628 1.642 1.631 1.622 1.619 1.624 E (Young's Modulus, Mpsi) - RUS 15.4 16.4 15.7 15.2 15.0 14.5 G (shear modulus, Mpsi) - RUS 6.10 6.49 6.21 6.01 5.92 5.76 Passon's Value - RUS 0.260 0.263 0.263 0.264 0.264 0.258 E (Young's Modulus, GPa) - RUS 106 113 108 105 103 100 G (shear modulus, GPa) - RUS 42.1 44.7 42.8 41.4 40.8 39.7 Failure toughness (MPa * sqrt(m)) 0.95 0.94 0.93 0.89 0.87 0.87 Standard deviation 0.03 0.06 0.01 0.03 0.03 0.03 Hardness - Vickers 200 g load Hardness - Standard Deviation

[0106] Table 7 Experimental Example 35 Experimental Example 36 Experimental Example 37 Experimental Example 38 Experimental Example 39 Experimental Example 40 Experimental Example 41 Experimental Example 42 Analysis of mole% SiO2 63.4 64.1 64.1 62.3 53.2 63.95 61.42 54.27 Al2O3 19.9 15.6 19.6 19.6 26.8 19.59 20.11 25.51 B2O3 Li2O 0.95 1.89 2.86 Na2O 0.8 2.6 1.7 3.6 5.2 0.82 1.8 2.72 MgO Y2 O3 14.7 14.6 14.5 14.4 14.6 14.5 14.6 14.46 La2 O3 1.1 2.9 Sowa 99.9 99.9 99.8 99.8 99.8 99.81 99.82 99.82 Al2O3 - R2O - RO 19.1 13.0 17.9 16.0 21.6 17.8 16.4 19.9 R2 O3 35.7 33.1 34.0 34.0 41.4 34.1 34.7 40.0 Density (g / cm3) 3.301 3.435 3.211 3.218 3.241 3.224 3.235 3.243 Mole volume (cm3 / mole) 28.95 28.72 28.76 28.66 29.51 28.56 28.50 28.96 Expansion (10⁻⁷ / °C) 46 53 46 51 53 46 50 52 Strain point (°C), by BBV 833 817 751 787 754 767 736 769 Annealing point (°C), by BBV 874 859 796 833 800 811 780 815 Softening point (°C), by PPV 1035 1014 977 1024 989 993 960 998 Δ(Softening Pt - Strain Pt) 202 197 226 236 235 227 224 229 Liquidus (°C): Test duration (hours) 72 72 72 72 72 72 72 72 Liquidus (°C) - Air >1330 >1330 1440 >1465 >1445 1420 1445 1425 Liquidus (°C) - Internal >1330 >1330 1445 1465 1445 1430 1445 1430 Liquidus (°C) - Platinum >1330 >1370 >1445 >1465 >1445 1440 1445 >1450 liquid phase unknown unknown unknown unknown unknown unknown unknown unknown Stress optical coefficient (nm / MPa / cm) 2.197 2.114 2.453 2.495 2.539 2.442 2.492 2.484 Refractive index at 589.3 1.645 1.655 1.606 1.605 1.601 1.607 1.606 1.604 E (Young's Modulus, Mpsi) - RUS 16.1 15.5 15.4 15.1 14.8 15.5 15.3 15.0 G (shear modulus, Mpsi) - RUS 6.33 6.13 6.10 6.00 5.88 6.15 6.07 5.96 Passon's Value - RUS 0.270 0.266 0.259 0.258 0.259 0.257 0.258 0.258 E (Young's Modulus, GPa) - RUS 111 107 106 104 102 107 105 103 G (shear modulus, GPa) - RUS 43.6 42.3 42.1 41.4 40.5 42.4 41.9 41.1 Failure toughness (MPa * sqrt(m)) 0.97 0.95 0.92 0.95 0.96 0.94 1.07 1.03 Standard deviation 0.02 0.05 0.03 0.01 0.02 0.06 0.00

[0107] Although the claimed subject matter has been described with reference to general embodiments, the claimed subject matter is not limited thereto. Rather, the appended claims should be interpreted broadly to include other variations and embodiments that can be performed by one of ordinary skill in the art to which this application pertains.

[0108] none

[0109] Domestic storage information (please note in order of storage institution, date, and number) none Overseas storage information (please note in the order of storage country, institution, date, and number) none

Claims

1. A glass substrate comprising: about 50 mol% to about 70 mol% of SiO2; about 15 mol% to about 30 mol% of Al2O3; less than 6 mol% of MgO; about 7 mol% to about 20 mol% of Y2O3; and, depending on the case, 0 mol% to about 9 mol% of La2O3, wherein the glass substrate comprises about 31.1 mol% to about 41.4 mol% of R2O3, and wherein the R2O3 comprises a total of Al2O3, Y2O3 and La2O3.

2. The glass substrate as claimed in claim 1, wherein the R2O3 is in the range of about 32 mol% to about 38 mol%.

3. The glass substrate as claimed in claim 1, wherein the molar ratio of [(Y2O3+La2O3) / Al2O3] of the glass substrate is in the range of about 0.3 to about 1.

7.

4. The glass substrate as claimed in claim 1, wherein the SiO2 content is in the range of about 52 mol% to about 70 mol%.

5. The glass substrate as claimed in claim 4, wherein the SiO2 content is in the range of about 52 mol% to about 66 mol%.

6. The glass substrate as claimed in claim 5, wherein the SiO2 content is in the range of about 54 moles to about 66 moles.

7. The glass substrate as claimed in claim 6, wherein the SiO2 content is in the range of about 60 mol% to about 66 mol%.

8. The glass substrate as claimed in claim 1, wherein the Al2O3 is in the range of about 16 mol% to about 30 mol%.

9. The glass substrate as claimed in claim 8, wherein the Al2O3 is in the range of about 17 mol% to about 30 mol%.

10. The glass substrate as claimed in claim 9, wherein the Al2O3 is in the range of about 18 mol% to about 30 mol%.

11. The glass substrate as claimed in claim 10, wherein the Al2O3 is in the range of about 18 mol% to about 28 mol%.

12. The glass substrate as claimed in claim 11, wherein the Al2O3 is in the range of about 18 mol% to about 25 mol%.

13. The glass substrate as claimed in claim 1, wherein the Y2O3 is in the range of about 8 mol% to about 20 mol%.

14. The glass substrate as claimed in claim 13, wherein the Y2O3 is in the range of about 9 mol% to about 20 mol%.

15. The glass substrate as claimed in claim 1, wherein the Y2O3 is in the range of about 7 mol% to about 16 mol%.

16. The glass substrate as claimed in claim 15, wherein the Y2O3 is in the range of about 7 mol% to about 15 mol%.

17. The glass substrate as claimed in claim 15, wherein the Y2O3 is in the range of about 8 mol% to about 16 mol%.

18. The glass substrate as claimed in claim 17, wherein the Y2O3 is in the range of about 10 mol% to about 16 mol%.

19. The glass substrate as claimed in claim 1, wherein the La2O3 is in the range of about 0.1 mol% to about 9 mol%.

20. The glass substrate as claimed in claim 19, wherein the La2O3 is in the range of about 1 mol% to about 9 mol%.

21. The glass substrate as claimed in claim 20, wherein the La2O3 is in the range of about 2 mol% to about 9 mol%.

22. The glass substrate as claimed in claim 21, wherein the La2O3 is in the range of about 3 mol% to about 9 mol%.

23. The glass substrate as claimed in claim 1, further comprising: 0 mol% to about 6 mol% of B2O3, wherein the glass substrate is substantially free of La2O3.

24. The glass substrate as claimed in claim 1 further comprises: 0 mol% to about 12 mol% of Li2O, Na2O, K2O or a combination thereof.

25. The glass substrate as claimed in claim 1, wherein the mole percentage difference of (Al2O3–R2O–RO) is in the range of about 7 to about 22, wherein R2O comprises an alkali metal oxide selected from the group consisting of Li2O, Na2O, K2O and any combination thereof, and RO comprises an alkaline earth metal oxide selected from the group consisting of MgO, SrO, BaO and any combination thereof.

26. The glass substrate as claimed in claim 1, wherein the glass substrate is substantially free of CaO, Eu2O3, Nb2O3, Si3N4, WO3, ZrO4 and TiO2.

27. The glass substrate as claimed in claim 1, wherein the glass substrate has a breaking toughness (KIC) in the range of about 0.87 to about 2.0 MPa.m0.

5.

28. The glass substrate as claimed in claim 1, wherein the glass substrate has a Young's modulus in the range of about 100 GPa to about 140 GPa and a shear modulus in the range of about 30 GPa to about 60 GPa.

29. A glass substrate comprising essentially the following components: about 50 mol% to about 70 mol% of SiO2; about 15 mol% to about 30 mol% of Al2O3; about 7 mol% to about 20 mol% of Y2O3; 0 mol% to about 9 mol% of La2O3; less than about 6 mol% of MgO; and 0 mol% to about 12 mol% of an alkali metal oxide selected from the group consisting of Li2O, Na2O, K2O, and combinations thereof, wherein the glass substrate comprises about 31.1 mol% to about 41.4 mol% of R2O3, wherein the R2O3 comprises a total of Al2O3, Y2O3, and La2O3.

30. The glass substrate as claimed in claim 29, wherein the molar ratio of [(Y2O3+La2O3) / Al2O3] of the glass substrate is in the range of about 0.3 to about 1.

7.

31. A glass article comprising a glass substrate as described in claim 1 or 29.

32. An electronic device comprising a glass substrate as described in claim 1 or 29.

33. The electronic device as described in claim 32, wherein the electronic device is used for display applications.

34. The electronic device as described in claim 32, wherein the electronic device is an information recording disc.

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