The invention relates to glass articles, such as for example glass tubes or flat glasses, where the material at the surface by a targeted process control has gradient material properties which in turn result in a compressive prestress of the surface. The invention also relates to a method for the production of the glass articles as well as their use.

The invention relates to glass articles, such as for example glass tubes or flat glasses, where the material at the surface by a targeted process control has gradient material properties which in turn result in a compressive prestress of the surface. The invention also relates to a method for the production of the glass articles as well as their use.

A composition comprising (i) a matrix comprising a metal oxide, metal sulphide and/or metal selenide as the matrix material, the metal oxide, metal sulphide and/or metal selenide comprising at least two metals M1 and M2, and (ii) a metal M3 which is mobile in the matrix. The atomic ratio of M1 to M2 is within the range of 75:25 to 99.99:0.01; the valence states of M1, M2 and M3 are all positive; the valence state of M1 is larger than the valence state of M2; the valence state of M2 is equal to or larger than the valence state of M3; and the metals M1, M2 and M3 are different.

A composition comprising (i) a matrix comprising a metal oxide, metal sulphide and/or metal selenide as the matrix material, the metal oxide, metal sulphide and/or metal selenide comprising at least two metals M1 and M2, and (ii) a metal M3 which is mobile in the matrix. The atomic ratio of M1 to M2 is within the range of 75:25 to 99.99:0.01; the valence states of M1, M2 and M3 are all positive; the valence state of M1 is larger than the valence state of M2; the valence state of M2 is equal to or larger than the valence state of M3; and the metals M1, M2 and M3 are different.

A pelletized expanded glass material is provided, which is particularly suitable as a growth support for microorganisms, especially for use in a biogas plant or an anaerobic sewage treatment plant. The production process of the invention for the pelletized expanded glass material contains the steps of: mixing a ground glass, an expanding agent and a binder to give a starting mixture. The starting mixture is pelletized to give ground glass pellet green bodies. The ground glass pellet green bodies are foamed to give expanded glass pellet particles at temperatures of 600 to 950 C. Accordingly, especially in the production of the starting mixture, minerals and or trace elements are added, which serve especially for the nutrient supply of microorganisms used in the biogas plant or the anaerobic sewage treatment plant.

Ultralow expansion titania-silica glass. The glass has high hydroxyl content and optionally include one or more dopants. Representative optional dopants include boron, alkali elements, alkaline earth elements or metals such as Nb, Ta, Al, Mn, Sn Cu and Sn. The glass is prepared by a process that includes steam consolidation to increase the hydroxyl content. The high hydroxyl content or combination of dopant(s) and high hydroxyl content lowers the fictive temperature of the glass to provide a glass having a very low coefficient of thermal expansion (CTE), low fictive temperature (T.sub.f), and low expansivity slope.

An optical glass having the following oxides in mass percentage relative to a total mass of the optical glass: 10.0%-30.0% SiO.sub.2, 10.0%-30.0% P.sub.2O.sub.5, 0.1%-5.0% B.sub.2O.sub.3, 0.1%-10.0% Al.sub.2O.sub.3, 0.1%-10.0% Rn oxides, 1.0%-20.0% R oxides, 0.1%-5.0% ZrO.sub.2, 10.0%-30.0% TiO.sub.2, 15.0%-50.0% Nb.sub.2O.sub.5, 0.1%-10.0% Ln oxides, and 0.1%-10.0% WO.sub.3, wherein TiO.sub.2+Nb.sub.2O.sub.5+P.sub.2O.sub.5+the R oxides accounts for 60.01% or above.