Abstract: The invention relates to lead-free optical glasses which have refractive indices nd of between 1.65 and 1.80 and Abbe numbers &ngr;d of between 21 and 33 and possess the following composition (in % by weight, based on oxide) SiO2 27-40; B2O3 0-<0.5; Al2O3 0-6; Na2O 7-18; K2O 1-10; BaO 1-10; SrO 0-3; CaO 0.5-5; MgO 0-3; with BaO+SrO+CaO+MgO<15; TiO2 21-37; ZrO2 0-7; Nb2O5 5-17; WO3 0.1-7.

Abstract: The lead-free optical light flint glass material has a refractive index nd between 1.54 and 1.61 and an Abbe number &ngr;d of between 38 and 45. It has a composition, based on oxide content, of SiO2 from 52 to 62% by weight, Al2O3 from 3 to 8% by weight, Na2O from 7 to 14% by weight, K2O from 8 to 14% by weight, TiO2 from 13 to 18% by weight, ZrO2 from 0 to 5% by weight, with at least one refining agent, if needed, in an amount suitable for the purposes of refining; and with the proviso that a sum total of Na2O and K2O present is greater than 18% by weight.

Abstract: The lead-free optical glasses have an index of refraction (nd) between 1.49 and 1.55 and an Abbé number (&ngr;d) between 47 and 59. They contain (in percent by weight on an oxide basis) 60 to 70, SiO2; 0.3 to 5, Al2O3; 16 to 25, Na2O; 0 to 9, TiO2; 0 to 7, advantageously 0.1 to 2, ZrO2; 0 to <0.5, Nb2O5; 0 to 7, Ta2O5 and 0 to 3, F. The lead-free optical glass is advantageously free of arsenic oxide, except for impurities, and contains antimony oxide as a fining agent.

Abstract: The invention relates to a meltdown device for the production of high-UV transmittive glass types, comprising

Abstract: The glass or glass-ceramic has the following composition (in % by weight based on oxide content): SiO2, 25 to 50; B2O3, >5 to 16; Al2O3, 10 to 17; P2O5, 0 to 8; Li2O,5 to 15; Na2O, 0 to 10; K2O, 0 to 10; MgO, 10 to 30; CaO, 0 to 10; SrO, 0 to 8; ZnO, 0 to 8; TiO2, 0.1 to 10; ZrO2, 0 to 8; and at least one refining agent, in an amount as needed according to its purpose. The sum total amount of divalent metal oxides (RO) present is less or equal to than 45% by weight based on oxide content and the sum total amount of alkali metal oxides (R2O) present is less than or equal to 30% by weight based on oxide content. The glass or glass-ceramic material generally has elasticity modulus values (E)>90×103 N/mm2 and <125×103 N/mm2, specific elasticity modulus values (E/&rgr;)>30×105 N cm/g and <45×105 N cm/g and thermal expansion coefficient values (&agr;20/300)>7.0×10−6/K and <11.0×10−6/K.

Abstract: The invention can relate to essentially lead-free optical glasses having a refractive index nd of from about 1.65 to about 1.87 and an Abbe number &ngr;d of from about 27 to about 43 and a composition (in % by weight, based on oxide) of SiO2 about 10-about 25, B2O3>about 10-about 25, Na2O about 2.5-about 10, K2O 0-about 3, CaO about 0.5-about 5, BaO about 15-about 30, ZnO about 5-about 15, TiO2 about 6-about 15, ZrO2 about 0.5-about 8, Y2O3 about 0.1-about 2, La2O3 about 0.5-about 8, Nb2O5 about 6-about 12, with La2O3+Nb2O5≦about 17,Ta2O5 0-about 1, and Gd2O3 0-about 1.

Abstract: The lead-free optical light flint glass material has a refractive index nd between 1.54 and 1.61 and an Abbe number &ngr;d of between 38 and 45. It has a composition, based on oxide content, of SiO2 from 52 to 62% by weight, Al2O3 from 3 to 8% by weight, Na2O from 7 to 14% by weight, K2O from 8 to 14% by weight, TiO2 from 13 to 18% by weight, ZrO2 from 0 to 5% by weight, with at least one refining agent, if needed, in an amount suitable for the purposes of refining; and with the proviso that a sum total of Na2O and K2O present is greater than 18% by weight.

Abstract: Magnetic disks comprising a substrate and glass materials which are used in the manufacture of hard disc substrates. The glasses can have the following compositions (in per cent by weight on an oxide basis): SiO2 10-30, Al2O3 0-5, B2O3 0-8, Li2O 0-8, Na2O 1-10, with Li2O+Na2O 5-10, K2O 0-3, MgO 5-16, CaO 0-15, with MgO+CaO>15-25, SrO+BaO 0-8, ZrO2 0-8, TiO2 7-25, La2O3 0-10, Nb2O5 5-20, V2O5 0-10, CeO2 0-1, As2O3+Sb2O3+F 0.1-1. These glasses can have high dimensional stability as a result of their high specific modulus of elasticity, to be especially suited for hard disk substrates.

Abstract: High E-moduli glasses and glass-ceramics are disclosed based on the SiO2—B2O3—RO—R2O—ZrO2—TiO2—Nb2O5—La2O3 system. The chemically pre-stressable glasses are lithium-poor or lithium-free. The glass-ceramics contain from 2 to 9 percent by weight lithium and the predominant crystalline phase is lithium titanate. These glasses and glass-ceramics particularly have a high specific E-modulus.