Abstract: A glass composition which contains Ce ions as a component substantially comprises, in terms of oxides, SiO2: 55 to 75 wt %, B2O3: 6 to 25 wt %, CeO2: 0.01 to 5 wt %, SnO: 0.01 to 5 wt %, Al2O3: 0 to 10 wt %, Li2O: 0 to 10 wt %, Na2O: 0 to 10 wt %, K2O: 0 to 10 wt %, MgO: 0 to 5 wt %, CaO: 0 to 10 wt %, SrO: 0 to 10 wt %, BaO 0 to 10 wt %, TiO2: 0 to 1.0 wt %, Fe2O3: 0.01 to 0.2 wt %, Sb2O3: 0 to 5 wt %, ZrO2: 0.01 to 5 wt %. By having such constituents, the glass composition is capable of suppressing transmission of ultraviolet light and solarization, and thus the glass composition hardly suffers from initial coloring or coloring during lamp production.

Abstract: <br></br> A glass composition contains the following constituents expressed in terms of oxides: 65 wt % to 75 wt % of SiO2; 1 wt % to 5 wt % of Al2O3; 0.5 wt % to 5 wt % of Li2O; 5 wt % to 12 wt % of Na2O; 3 wt % to 7 wt % of K2O; 12 wt % to 18 wt % of Li2O+Na2O+K2O; 2.1 wt % to 7 wt % of MgO; 2 wt % to 7 wt % of CaO; 0 wt % to 0.9 wt % of SrO; 7.1 wt % to 12 wt % of BaO; and substantially no PbO. The glass composition for a lamp is substantially lead-free, has an electrical insulation suitable for an illumination purpose, and further reduces the risk of devitrification.

Abstract: A glass composition which contains Ce ions as a component substantially comprises, in terms of oxides, SiO2: 55 to 75 wt %, B2O3: 6 to 25 wt %, CeO2: 0.01 to 5 wt %, SnO: 0.01 to 5 wt %, Al2O3: 0 to 10 wt %, Li2O: 0 to 10 wt %, Na2O: 0 to 10 wt %, K2O: 0 to 10 wt %, MgO: 0 to 5 wt %, CaO: 0 to 10 wt %, SrO: 0 to 10 wt %, BaO 0 to 10 wt %, TiO2: 0 to 1.0 wt %, Fe2O3: 0.01 to 0.2 wt %, Sb2O3: 0 to 5 wt %, ZrO2: 0.01 to 5 wt %. By having such constituents, the glass composition is capable of suppressing transmission of ultraviolet light and solarization, and thus the glass composition hardly suffers from initial coloring or coloring during lamp production.

Abstract: Disclosed is a glass composition for lamps which contains Mo ions as a component, substantially comprising the following that are expressed in terms of oxides: SiO2: 55 to 75 wt %, B2O3: 11 to 25 wt %, MoO3: 0.3 to 1.4 wt %, Al2O3: 1 to 10 wt %, Li2O: 0 to 10 wt %, Na2O: 0 to 10 wt %, K2O: 0 to 10 wt %, Li2O+Na2O+K2O: 1 to 10 wt %, MgO: 0 to 5 wt %, CaO: 0 to 10 wt %, SrO: 0 to 10 wt %, BaO: 0 to 10 wt %, MgO+CaO+SrO+BaO: 1 to 10 wt %. By having such a constitution, the glass composition has a high ultra violet shielding effect and hardly suffers from coloring.