To provide a crystallized glass substrate including a surface with a compressive stress layer, where a stress depth DOL.sub.zero of the compressive stress layer, at which the compressive stress is 0 MPa, is 45 to 200 μm, 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.

A process for the manufacture of a glass-ceramic article exhibiting properties of resistance to scratches, greasy marks, adhesion of dirt and light scattering. The glass-ceramic article includes a surface, the surface arithmetic roughness of which is between 2 μm and 7 μm and the roughness being obtained using a chemical surface treatment. The glass-ceramic article is particularly suitable for use as a cooking surface and/or as surface for the preparation of foodstuffs.

A process for the manufacture of a glass-ceramic article exhibiting properties of resistance to scratches, greasy marks, adhesion of dirt and light scattering. The glass-ceramic article includes a surface, the surface arithmetic roughness of which is between 2 μm and 7 μm and the roughness being obtained using a chemical surface treatment. The glass-ceramic article is particularly suitable for use as a cooking surface and/or as surface for the preparation of foodstuffs.

Embodiments of a glass-based article including a first surface and a second surface opposing the first surface defining a thickness (t) of about 3 millimeters or less (e.g., about 1 millimeter or less), and a stress profile, wherein all points of the stress profile between a thickness range from about 0.Math.t up to 0.3.Math.t and from greater than 0.7.Math.t, comprise a tangent that is less than about −0.1 MPa/micrometers or greater than about 0.1 MPa/micrometers, are disclosed. In some embodiments, the glass-based article includes a non-zero metal oxide concentration that varies along at least a portion of the thickness (e.g., 0.Math.t to about 0.3.Math.t). In some embodiments, the concentration of metal oxide or alkali metal oxide decreases from the first surface to a point between the first surface and the second surface and increases from the point to the second surface. The concentration of the metal oxide may be about 0.05 mol % or greater or about 0.5 mol % or greater throughout the thickness. Methods for forming such glass-based articles are also disclosed.

Embodiments of a glass-based article including a first surface and a second surface opposing the first surface defining a thickness (t) of about 3 millimeters or less (e.g., about 1 millimeter or less), and a stress profile, wherein all points of the stress profile between a thickness range from about 0.Math.t up to 0.3.Math.t and from greater than 0.7.Math.t, comprise a tangent that is less than about −0.1 MPa/micrometers or greater than about 0.1 MPa/micrometers, are disclosed. In some embodiments, the glass-based article includes a non-zero metal oxide concentration that varies along at least a portion of the thickness (e.g., 0.Math.t to about 0.3.Math.t). In some embodiments, the concentration of metal oxide or alkali metal oxide decreases from the first surface to a point between the first surface and the second surface and increases from the point to the second surface. The concentration of the metal oxide may be about 0.05 mol % or greater or about 0.5 mol % or greater throughout the thickness. Methods for forming such glass-based articles are also disclosed.

Lithium silicate-diopside glass ceramics are described which are characterized by a controllable translucence and can be satisfactorily processed mechanically and therefore can be used in particular as restoration material in dentistry.

A transparent glass-ceramic composition including: of the formula Ta.sub.2-xAl.sub.xO.sub.5-x where x is less than 1; of the formula AlTaO.sub.4; of the formula AlPO.sub.4; a mixture of AlTaO.sub.4 and AlPO.sub.4; or a mixture of the formula Ta.sub.2-xAl.sub.xO.sub.5-x, AlTaO.sub.4, and AlPO.sub.4. Also disclosed are transparent glass-ceramic compositions including, for example, a dopant as defined herein, or a supplemental metal oxide or metalloid oxide of M.sub.xO.sub.y, M.sub.xM′.sub.xO.sub.y, or a mixture thereof such as oxides of Nb, Ti, W, B, or Ga, as defined herein. Also disclosed are methods of making the disclosed transparent glass-ceramic compositions, and optical articles, optical components, and optical apparatus thereof.

The present invention relates to a 3D printer printhead, a 3D printer using the same, a method for manufacturing a molded product by using the 3D printer, a method for manufacturing an artificial tooth by using the 3D printer, and a method for manufacturing a machinable glass ceramic molded product by using the 3D printer, the 3D printer printhead comprising: an inlet through which glass wire, which is a raw material, is introduced; a heating means for heating the glass wire introduced through the inlet; a melting furnace for providing a space in which the glass wire is fused; and a nozzle connected to the lower part of the melting furnace so as to temporarily store the fused glass or discharge a targeted amount of the fused glass, wherein the melting furnace includes an exterior frame made from a heat resistant material and an interior frame having a crucible shape, and the interior frame is made from platinum (Pt), a Pt alloy or graphite, which have a low contact angle, or a material having a surface coated with Pt or a diamond-like carbon (DLC) so as to prevent the fused glass from sticking thereto. According to the present invention, the molded product, the artificial tooth, and the machinable glass ceramic molded product can be manufactured with excellent mechanical properties, thermal durability, chemical durability and oxidation resistance and outstanding texture by using the glass wire as a raw material.

A method of processing a glass material includes guiding and/or focusing light from a light source to glass material in a hot stage of a processing system, where the light source provides light at a wavelength λ that interacts with crystals that may be formed in the glass material. The method includes collecting and/or guiding light directed from the glass material in the hot stage to a wavelength separator, and separating the light directed from the glass material to provide a spectrum δ having wavelengths that are within about twenty nanometers of the wavelength λ. The method includes observing with a detector light of the spectrum δ to identify nano-scale shifts in the wavelength λ caused by interaction with crystals, if present, within the glass material in the hot stage of the processing system.

A transparent β-quartz glass ceramic is provided. The glass ceramic includes a primary crystal phase including a β-quartz solid solution, a secondary crystal phase including tetragonal ZrO.sub.2, and a lithium aluminosilicate amorphous phase. The glass ceramic may be ion exchanged utilizing molten nitrate salt baths. Methods for producing the glass ceramic are also provided.