A thermally tempered aluminosilicate glass-ceramic composition includes a crystalline phase and a residual glass phase, wherein the two phases form a system wherein the thermal expansion curve of the system has two distinct sections diverging from an inflection point temperature in the range of about 450° C. to about 600° C., and wherein the difference between coefficient of thermal expansion of the glass-ceramic below and above the inflection point is greater than about 4 ppm/° C.

Provided is a silica glass member which exhibits high optical transparency to vacuum ultraviolet light and has a low thermal expansion coefficient of 4.0−10.sup.−7/K or less at near room temperature, particularly a silica glass member which is suitable as a photomask substrate to be used in a double patterning exposure process using an ArF excimer laser (193 nm) as a light source. The silica glass member is used in a photolithography process using a vacuum ultraviolet light source, in which the fluorine concentration is 1 wt % or more and 5 wt % or less, and the thermal expansion coefficient at from 20° C. to 50° C. is 4.0×10.sup.−7/K or less.

Provided is a silica glass member which exhibits high optical transparency to vacuum ultraviolet light and has a low thermal expansion coefficient of 4.0−10.sup.−7/K or less at near room temperature, particularly a silica glass member which is suitable as a photomask substrate to be used in a double patterning exposure process using an ArF excimer laser (193 nm) as a light source. The silica glass member is used in a photolithography process using a vacuum ultraviolet light source, in which the fluorine concentration is 1 wt % or more and 5 wt % or less, and the thermal expansion coefficient at from 20° C. to 50° C. is 4.0×10.sup.−7/K or less.

The present invention relates to a method for manufacturing tempered glass and, more specifically, to a method for manufacturing alkali-free glass which has the thickness of 2.0 mm or less into tempered glass by means of heat treatment and surface treatment using fluosilicic acid. To this end, the present invention provides a method for manufacturing tempered glass, the method comprising: a preparation step for preparing alkali-free glass; a surface treatment step for surface-treating the alkali-free glass by means of a surface treatment solution comprising fluosilicic acid and thereby generating on the surface of the alkali-free glass a porous SiO.sub.2-rich layer of which the coefficient of thermal expansion (CTE) is smaller than the CTE of the inner part of the alkali-free glass; and a heat treatment step for heat-treating the alkali-free glass that has been surface-treated and thereby generating compressive stress on the surface of the alkali-free glass.

The present invention relates to a method for manufacturing tempered glass and, more specifically, to a method for manufacturing alkali-free glass which has the thickness of 2.0 mm or less into tempered glass by means of heat treatment and surface treatment using fluosilicic acid. To this end, the present invention provides a method for manufacturing tempered glass, the method comprising: a preparation step for preparing alkali-free glass; a surface treatment step for surface-treating the alkali-free glass by means of a surface treatment solution comprising fluosilicic acid and thereby generating on the surface of the alkali-free glass a porous SiO.sub.2-rich layer of which the coefficient of thermal expansion (CTE) is smaller than the CTE of the inner part of the alkali-free glass; and a heat treatment step for heat-treating the alkali-free glass that has been surface-treated and thereby generating compressive stress on the surface of the alkali-free glass.

The present invention provides for synthesizing high optical quality multicomponent chalcogenide glasses without refractive index perturbations due to striae, phase separation or crystal formation using a two-zone furnace and multiple fining steps. The top and bottom zones are initially heated to the same temperature, and then a temperature gradient is created between the top zone and the bottom zone. The fining and cooling phase is divided into multiple steps with multiple temperature holds.

The invention relates to methods of increasing the strength, especially the flexural strength, of a glass article produced from a glass material. The method includes the step of heating the glass article to a first temperature above the transformation temperature of the glass material, the step of shock cooling the glass article to a second temperature below the transformation temperature of the glass material, and the step of performing an ion exchange process at the second temperature.

The invention relates to methods of increasing the strength, especially the flexural strength, of a glass article produced from a glass material. The method includes the step of heating the glass article to a first temperature above the transformation temperature of the glass material, the step of shock cooling the glass article to a second temperature below the transformation temperature of the glass material, and the step of performing an ion exchange process at the second temperature.

The invention relates to a method for producing a glass article. The method includes the step of producing a glass body from a glass material and the further step of bringing the glass body, at a primary temperature which is at most 50 Kelvin below and at most 30 Kelvin above the Littleton softening point of the glass material, into contact with a liquid cooling agent which has a cooling agent temperature which is at least 200 Kelvin and at most 550 Kelvin below the primary temperature.

Methods of forming a foldable substrate comprise providing a glass-based substrate comprising a first compressive stress region extending to an existing first depth of compression from an existing first major surface. Methods comprise contacting the existing first major surface with a solution to remove an outer compressive layer of the first compressive stress region to form a new first major surface. The outer compressive layer ranges from about 0.05 micrometers to about 5 micrometers. The solution can comprise a first temperature in a range from about 60° C. to about 120° C. The solution can comprise an alkaline solution comprising about 10 wt % or more of a hydroxide-containing base. In aspects, the method can comprise one or more of: attaching an adhesive layer to the new first major surface, attaching a display device to the new first major surface, or disposing a coating over the new first major surface.