Abstract: A method for producing a glass ceramic includes: providing a batch of raw materials; heating the batch of raw materials until a melt is obtained, the batch of raw materials being heated at least in a plurality of sections to a temperature above T3 which corresponds to a viscosity of a molten glass of 103 dPa*s; refining the melt, the melt being heated at least in a plurality of sections to a temperature above T2.5 which corresponds to a viscosity of the molten glass of 102.5 dPa*s; obtaining a refined glass which is configured for being ceramized to form a glass ceramic material; and ceramizing a glass which is configured for being ceramized to form the glass ceramic material, at least one of the step of heating until the melt is obtained and the step of refining being performed with heating by way of H2 and O2 combustion.

Abstract: A method for melting and/or refining glass, glass ceramic or glass which can be ceramized to form glass ceramic includes: providing a batch of raw materials; heating the batch until a melt of molten glass is obtained, the batch being heated at least in sections to a temperature above T3 which corresponds to a viscosity of the molten glass of 103 dPa*s; refining the melt, the melt being heated at least in sections to a temperature above T2.5 which corresponds to a viscosity of the molten glass of 102.5 dPa*s, refining of the melt includes adjusting an oxygen partial pressure p(O2) which is reduced by at least 60% relative to an O2 saturation in the melt at temperature T3; and obtaining a re-fined glass, a refined glass ceramic or a refined glass which can be ceramized to form glass ceramic.

Abstract: A glass-ceramic component is provided that has a low average coefficient of thermal expansion (CTE) and a high CTE homogeneity. The use of such a component and a process for producing such a component are also provided.

Abstract: A glass-ceramic component is provided that has a low average coefficient of thermal expansion (CTE) and a high CTE homogeneity. The use of such a component and a process for producing such a component are also provided.

Abstract: The lead-free and arsenic-free optical glasses have a refractive index of 1.83?nd?1.95 and an Abbé number of 24??d?35, good chemical resistance, excellent crystallization stability and a composition, in wt. % based on oxide content, of SiO2, 2-8; B2O3, 15-22; La2O3, 35-42; ZnO, 10-18; TiO2, 9-15; ZrO2, 3-10; Nb2O5, 4-10; and WO3, >0.5-3. Besides containing at most 5 wt. % of each of GeO2, Ag2O and BaO and conventional fining agents, they may also contain at most in total 5 wt. % of Al2O3, MgO, CaO, SrO, P2O5 and up to at most in total 5 wt. % of the components F, Ta2O5. The glasses are preferably free of alkali metal oxides, Bi2O3, Y2O3, Gd2O3 and/or Yb2O3. Optical elements made from the optical glass are also described.

Abstract: The lead-free and arsenic-free optical glasses have a refractive index of 1.83?nd?1.95 and an Abbé number of 24??d?35, good chemical resistance, excellent crystallization stability and a composition, in wt. % based on oxide content, of SiO2, 2-8; B2O3, 15-22; La2O3, 35-42; ZnO, 10-18; TiO2, 9-15; ZrO2, 3-10; Nb2O5, 4-10; and WO3, >0.5-3. Besides containing at most 5 wt. % of each of GeO2, Ag2O and BaO and conventional fining agents, they may also contain at most in total 5 wt. % of Al2O3, MgO, CaO, SrO, P2O5 and up to at most in total 5 wt. % of the components F, Ta2O5. The glasses are preferably free of alkali metal oxides, Bi2O3, Y2O3, Gd2O3 and/or Yb2O3. Optical elements made from the optical glass are also described.