A method for homogenizing glass includes the method: providing a cylindrical blank composed of the glass having a cylindrical outer surface that extends along a longitudinal axis of the blank between a first end face and a second end face, forming a shear zone in the blank by softening a longitudinal section of the blank and subjecting it to a thermal-mechanical intermixing treatment, and displacing the shear zone along the longitudinal axis of the blank. The displacement of the shear zone along the longitudinal axis of the blank is superimposed by a simultaneous oscillating motion of the shear zone along the longitudinal axis of the blank. The first end of the blank is rotated at a first rotational speed and the second end of the blank is rotated at a second rotational speed. An oscillating motion of the shear zone is generated by periodically varying the first and/or second rotational speed.

A method for homogenizing glass includes the method: providing a cylindrical blank composed of the glass having a cylindrical outer surface that extends along a longitudinal axis of the blank between a first end face and a second end face, forming a shear zone in the blank by softening a longitudinal section of the blank and subjecting it to a thermal-mechanical intermixing treatment, and displacing the shear zone along the longitudinal axis of the blank. The displacement of the shear zone along the longitudinal axis of the blank is superimposed by a simultaneous oscillating motion of the shear zone along the longitudinal axis of the blank. The first end of the blank is rotated at a first rotational speed and the second end of the blank is rotated at a second rotational speed. An oscillating motion of the shear zone is generated by periodically varying the first and/or second rotational speed.

The present invention relates to a chemically strengthened glass ceramic including a crystalline phase, having two main surfaces opposed to each other, and including an amorphized region in a surface layer of at least one of the main surfaces and a crystallized region inside the glass, in which the amorphized region has a crystallinity of 10 vol % or less at a depth of 100 nm from an outermost surface of the glass.

Provided is a method for producing a porous glass member whereby cracking during production is less likely to occur and a porous glass member having excellent alkali resistance can be produced. A method for producing a porous glass member includes the steps of: subjecting a glass base material containing, in terms of % by mole, 40 to 80% SiO.sub.2, over 0 to 40% B.sub.2O.sub.3, 0 to 20% Li.sub.2O, 0 to 20% Na.sub.2O, 0 to 20% K.sub.2O, over 0 to 2% P.sub.2O.sub.5, over 0 to 20% ZrO.sub.2, 0 to 10% Al.sub.2O.sub.3, and 0 to 20% RO (where R represents at least one selected from among Mg, Ca, Sr, and Ba) to thermal treatment to separate the glass base material into two phases; and removing one of the two phases with an acid.

Provided is a method for producing a porous glass member whereby cracking during production is less likely to occur and a porous glass member having excellent alkali resistance can be produced. A method for producing a porous glass member includes the steps of: subjecting a glass base material containing, in terms of % by mole, 40 to 80% SiO.sub.2, over 0 to 40% B.sub.2O.sub.3, 0 to 20% Li.sub.2O, 0 to 20% Na.sub.2O, 0 to 20% K.sub.2O, over 0 to 2% P.sub.2O.sub.5, over 0 to 20% ZrO.sub.2, 0 to 10% Al.sub.2O.sub.3, and 0 to 20% RO (where R represents at least one selected from among Mg, Ca, Sr, and Ba) to thermal treatment to separate the glass base material into two phases; and removing one of the two phases with an acid.

A method for producing an intermediate glass plate includes a defect formation step, a separation step, and a polishing step. In the defect formation step, a defect is formed on main surfaces of glass blanks by irradiating a laminate of the glass blanks with a laser beam from one side in a lamination direction in which the glass blanks are laminated, along the lamination direction, and moving the laser beam relative to the laminate such that a circle is drawn in a view from the main surfaces of the glass blanks. In the separation step, a cylindrical laminate is formed by separating a removal target portion along the defect while maintaining the laminate. In the polishing step, a side wall surface of the laminate is polished while maintaining the cylindrical laminate so as to obtain a disk-shaped intermediate glass plate that has been subjected to edge surface polishing.

A method for producing an intermediate glass plate includes a defect formation step, a separation step, and a polishing step. In the defect formation step, a defect is formed on main surfaces of glass blanks by irradiating a laminate of the glass blanks with a laser beam from one side in a lamination direction in which the glass blanks are laminated, along the lamination direction, and moving the laser beam relative to the laminate such that a circle is drawn in a view from the main surfaces of the glass blanks. In the separation step, a cylindrical laminate is formed by separating a removal target portion along the defect while maintaining the laminate. In the polishing step, a side wall surface of the laminate is polished while maintaining the cylindrical laminate so as to obtain a disk-shaped intermediate glass plate that has been subjected to edge surface polishing.

An environment-friendly glass material, including components like SiO.sub.2, ZnO, alkali metal oxide and S, but does not contain Cd, wherein when the thickness of the environment-friendly glass material is 3 mm, the cutoff wavelength is above 550 nm, the transmittance at 800-850 nm is above 75%, the transmittance at 850-900 nm is above 80%, the transmittance at 900-1000 nm is above 83%, and the transmittance at 1000-2000 nm is above 85%. Through rational component design, the glass material of the present invention realizes environmental protection, UV and visible light cutoff, and high near-infrared transmittance at the same time.

A method for producing rare earth metal-doped quartz glass includes the steps of (a) providing a blank of the rare earth metal-doped quartz glass, and (b) homogenizing the blank by softening the blank zone by zone in a heating zone and by twisting the softened zone along a rotation axis. Some rare earth metals, however, show a discoloration of the quartz glass, which hints at an unforeseeable and undesired change in the chemical composition or possibly at an inhomogeneous distribution of the dopants. To avoid this drawback and to provide a modified method which ensures the production of rare earth metal-doped quartz glass with reproducible properties, during homogenization according to method step (b), the blank is softened under the action of an oxidizingly acting or a neutral plasma.

A strengthened glass article (100), such as a substrate for a p-Si based transistors, includes first and second glass cladding layers (104, 106) and a glass core layer (102) disposed therebetween. A coefficient of thermal expansion [CTE] of each cladding layer (104, 106), which can be made of the same glass, is at least 1×10.sup.−7° C..sup.−1 less than that of the core layer (102). Each of the core and cladding layers has a strain point less than 700° C. A compaction of the glass article (100) is at most about 20 ppm [see FIG. 1]. A method includes forming a glass article and/or heating a glass article to a first temperature of at least about 400° C. The glass article has a glass core layer (102) and a glass cladding layer (104, 106) adjacent to the core layer. The glass article is maintained at a temperature within a range of from 400° C. to 600° C. for a holding period from 30 to 90 minutes and subsequently cooled to a temperature of at most 50° C. over a cooling period from 30 seconds to 5 minutes. The glass article (100) for heat strengthening may have been produced by the fusion overflow down draw process, e.g. as depicted in FIG. 3.