Abstract: Provided is a crystallized glass substrate including a surface with a compressive stress layer, in which a gradient A of a surface compressive stress from an outermost surface to a depth of 6 ?m in the compressive stress layer is 50.0 to 110.0 MPa/?m, a gradient B of a surface compressive stress from a depth of (a stress depth DOLzero—10 ?m) to the stress depth DOLzero is 2.5 to 15.0 MPa/?m, where the stress depth DOLzero is a depth of the compressive stress layer at a surface compressive stress of 0 MPa, and a hardness of the outermost surface at an indentation depth of 20 nm is 7.50 to 9.50 GPa.

Abstract: To provide a crystallized glass substrate including a surface with a compressive stress layer, in which a stress depth DOLzero of the compressive stress layer, at which the compressive stress is 0 MPa, is 45 to 200 ?m, a compressive stress CS on an outermost surface of the compressive stress layer is 400 to 1400 MPa, and CS×DOLzero, which is a product of the compressive stress CS on the outermost surface and the stress depth DOLzero(?m), is 4.8×104 or more.

Abstract: To provide a crystallized glass substrate that is hard and resistant to fracture and that is also resistant to shattering upon breakage. A crystallized glass substrate includes a crystallized glass serving as a base material and a compressive stress layer forming a surface thereof. The crystallized glass contains, in % by weight on an oxide basis, 40.0% to 70.0% of a SiO2 component, 11.0% to 25.0% of an Al2O3 component, 5.0% to 19.0% of a Na2O component, 0% to 9.0% of a K2O component, 1.0% to 18.0% of one or more selected from a MgO component and a ZnO component, 0% to 3.0% of a CaO component, and 0.5% to 12.0% of a TiO2 component. The SiO2 component, the Al2O3 component, the Na2O component, the one or more selected from the MgO component and the ZnO component, and the TiO2 component are present in a total amount of 90% or more. The compressive stress layer has a depth of layer of 40 ?m or more. The compressive stress layer has a surface compressive stress of 750 MPa or more.

Abstract: A crystallized glass includes a crystallized glass mother material, and, in a surface, a compressive stress layer, wherein the crystallized glass has, for a thickness of 10 mm, a light transmittance of, including reflection loss, 80% at a wavelength in 400 to 669 nm, and has a Vickers hardness [Hv] of 835 to 1300. In the crystallized glass, the crystallized glass mother material contains, in % by weight on an oxide basis, 40.0% to 70.0% of a SiO2 component, 11.0% to 25.0% of an Al2O3 component, 5.0% to 19.0% of a Na2O component, 0% to 9.0% of a K2O component, 1.0% to 18.0% of a MgO component, 0% to 3.0% of a CaO component, and 0.5% to 12.0% of a TiO2 component, and a total content of the SiO2 component, the Al2O3 component, the Na2O component, the K2O component, the MgO component, and the TiO2 component is 90% or more.

Abstract: To provide a crystallized glass substrate including a surface with a compressive stress layer, where a stress depth DOLzero of the compressive stress layer, at which the compressive stress is 0 MPa, is 45 to 200 ?m, a compressive stress CS on an outermost surface of the compressive stress layer is 400 to 1400 MPa, and a central stress CT determined by using curve analysis is 55 to 300 MPa.

Abstract: A method for manufacturing a crystallized glass member having a curved shape includes a deforming step of deforming at least a portion of a glass plate into a curved shape by an external force that acts on the glass plate while maintaining the temperature of the glass plate within a first temperature range and precipitating crystals from the glass plate. In the method for manufacturing a crystallized glass member having a curved shape according to Claim 1, the first temperature range is from [At ?40]° C. to [At +40]° C., wherein At (° C.) is a yield point of the glass plate.

Abstract: To provide a crystallized glass substrate including a surface with a compressive stress layer, in which, CS is 400 to 1400 MPa and CT×(T?2×DOLzero)/CS×DOLzero is 0.60 or more, where CS (MPa) denotes a compressive stress on an outermost surface of the compressive stress layer, DOLzero (?m) denotes a stress depth of the compressive stress layer at which the compressive stress is 0 MPa, CT (MPa) denotes a central stress determined by curve analysis, and T (?m) denotes a thickness of the substrate.

Abstract: To provide a crystallized glass substrate including a surface with a compressive stress layer, in which a compressive stress CS (MPa) on an outermost surface of the compressive stress layer is 400 to 1400 MPa, and DOL50%/DOLzero is 0.30 or more, where DOL50% (?m) is a depth at which the value of the compressive stress is 50% of the CS and DOLzero (?m) is a depth at which the value of the compressive stress is 0 MPa.

Abstract: To obtain a crystallized glass member having a curved shape and provide a method for producing the same. A method for producing a crystallized glass member having a curved shape, including a deformation step for adjusting the temperature of a plate glass to a first temperature zone from higher than [At+40]° C. to [At+146]° C. or lower, where At is the yield point (° C.) of the plate glass and deforming at least part of the plate glass into a curved shape by external force acting on the plate glass while precipitating crystals from the plate glass.

Abstract: A crystallized glass substrate includes a crystallized glass serving as a base material and a compressive stress layer forming a surface thereof. The crystallized glass contains, in % by weight on an oxide basis, 40.0% to 70.0% of a SiO2 component, 11.0% to 25.0% of an Al2O3 component, 5.0% to 19.0% of a Na2O component, 0% to 9.0% of a K2O component, 1.0% to 18.0% of one or more selected from a MgO component and a ZnO component, 0% to 3.0% of a CaO component, and 0.5% to 12.0% of a TiO2 component. The SiO2 component, the Al2O3 component, the Na2O component, the one or more selected from the MgO component and the ZnO component, and the TiO2 component are present in a total amount of 90% or more.

Abstract: A crystallized glass includes a crystallized glass mother material, and, in a surface, a compressive stress layer, wherein the crystallized glass has, for a thickness of 10 mm, a light transmittance of, including reflection loss, 80% at a wavelength in 400 to 669 nm, and has a Vickers hardness [Hv] of 835 to 1300. In the crystallized glass, the crystallized glass mother material contains, in % by weight on an oxide basis, 40.0% to 70.0% of a SiO2 component, 11.0% to 25.0% of an Al2O3 component, 5.0% to 19.0% of a Na2O component, 0% to 9.0% of a K2O component, 1.0% to 18.0% of a MgO component, 0% to 3.0% of a CaO component, and 0.5% to 12.0% of a TiO2 component, and a total content of the SiO2 component, the Al2O3 component, the Na2O component, the K2O component, the MgO component, and the TiO2 component is 90% or more.

Abstract: It is an object of the present invention to provide a crystallized glass which has various properties required for employing the substrate for information recording medium of the next generation, and also has significantly low specific gravity; and a crystallized glass substrate for information recording medium. A crystallized glass containing, as a crystal phase, one or more selected from RAl2O4 and R2TiO4 (wherein R is one or more selected from Mg and Fe), the crystallized glass comprising the components of SiO2 of 50% to 70%, Al2O3 of 10% to 26%, TiO2 of 1 to 15%, MgO of 2.5% to 25%, FeO of 0% to 8%, and ZnO of 0% to less than 2%, expressed in terms of mass percentage on an oxide basis, wherein the value of (Al2O3+MgO)/SiO2 is 0.30 or more and 0.65 or less, and a specific gravity is less than 2.63.

Abstract: To provide a substrate for information recording medium having various properties, in particular higher fracture toughness, required for application of the substrate for information recording medium of the next generation such as perpendicular magnetic recording system, etc. and a material with excellent workability for such purpose. A crystallized glass substrate for information recording medium, consisting of a crystallized glass which comprises one or more selected from RAl2O4 and R2TiO4 as a main crystal phase, in which R is one or more selected from Zn, Mg and Fe, and in which the main crystal phase has a crystal grain size in a range of from 0.5 nm to 20 nm, a degree of crystallinity of 15% or less, and a specific gravity of 3.00 or less.

Abstract: It is an object of the present invention to provide a crystallized glass which has various properties required for employing the substrate for information recording medium of the next generation, and also has significantly low specific gravity; and a crystallized glass substrate for information recording medium. A crystallized glass containing, as a crystal phase, one or more selected from RAl2O4 and R2TiO4 (wherein R is one or more selected from Mg and Fe), the crystallized glass comprising the components of SiO2 of 50% to 70%, Al2O3 of 10% to 26%, TiO2 of 1 to 15%, MgO of 2.5% to 25%, FeO of 0% to 8%, and ZnO of 0% to less than 2%, expressed in terms of mass percentage on an oxide basis, wherein the value of (Al2O3+MgO)/SiO2 is 0.30 or more and 0.65 or less, and a specific gravity is less than 2.63.

Abstract: A manufacturing method is provided for manufacturing a substrate for information storage media having various properties that are demanded for a next generation of information storage media substrate purposes exemplified by perpendicular magnetic recording systems, etc., and above all, having high fracture toughness and a smooth surface at low cost. The method of manufacturing a substrate for information storage media includes a step of preparing glass material of a plate shape containing SiO2 component, Al2O3 component, and R?2O component, R? being at least one selected from Li, Na, and K, and the step of lapping includes at least one sub-step of lapping the glass material with a diamond pad.

Abstract: There is provided a glass substrate which has the properties required in the use as a substrate for an information recording medium of the next generation such as a perpendicular magnetic recording system, and can be applied as a substrate for an information recording medium of the next generation particularly on the premise of using the glass substrate in a dynamic environment. More particularly, there is provided a glass substrate for an information recording medium which has sufficiently high surface hardness, has a good balance between specific gravity and mechanical strength, and has high strength to withstand high speed rotation or drop impact, and which can be produced with a high productivity adequate for a direct press method, without the occurrence of bubbles in the glass blank or reboil upon pressing even if arsenic components or antimony components are not substantially used.

Abstract: To provide a substrate for information recording medium having various properties, in particular higher fracture toughness, required for application of the substrate for information recording medium of the next generation such as perpendicular magnetic recording system, etc. and a material with excellent workability for such purpose. A crystallized glass substrate for information recording medium, consisting of a crystallized glass which comprises one or more selected from RAl2O4 and R2TiO4 as a main crystal phase, in which R is one or more selected from Zn, Mg and Fe, and in which the main crystal phase has a crystal grain size in a range of from 0.5 nm to 20 nm, a degree of crystallinity of 15% or less, and a specific gravity of 3.00 or less.

Abstract: To provide a substrate for information recording medium having various properties, in particular higher fracture toughness, required for application of the substrate for information recording medium of the next generation such as perpendicular magnetic recording system, etc. and a material with excellent workability for such purpose. A crystallized glass substrate for information recording medium, consisting of a crystallized glass which comprises one or more selected from RAl2O4 and R2TiO4 as a main crystal phase, in which R is one or more selected from Zn, Mg and Fe, and in which the main crystal phase has a crystal grain size in a range of from 0.5 nm to 20 nm, a degree of crystallinity of 15% or less, and a specific gravity of 3.00 or less.

Abstract: Glass-ceramics include SiO2, Al2O3 and Li2O on oxide basis. In the glass-ceramics, total amount in mass % of SiO2 and Al2O3 is less than 77% and Li2O/(SiO2+Al2O3) which is the ratio in mass % of the amount of Li2O to the total amount of SiO2 and Al2O3 is 0.064 or over. The glass-ceramics include at least one crystal phase selected from the group consisting of ?-quartz, ?-quartz solid solution, ?-eucryptite, ?-eucryptite solid solution, ?-spodumene and ?-spodumene solid solution.

Abstract: For providing glass-ceramics having properties suitable for use as a substrate of an information storage medium of next generation such as one for the perpendicular magnetic recording system without employing arsenic and antimony components which adversely affect human beings and the environment, there are provided glass-ceramics comprising SiO2, Li2O and Al2O3 on oxide basis, comprising lithium disilicate as a crystal phase, and comprising one or more elements selected from the group consisting of Sn, Ce, Mn, W, Ta, Bi, Nb, S, Cl and F.