Abstract: Glass comprises essentially 20-70% SiO2, 10-50% TiO2+Nb2O5+SnO2+Ta2O5+WO3+CeO2, 0-50% MgO+CaO+SrO+BaO+ZnO, and 0-30% B2O3+Al2O3, in molar percentage terms based on the oxides; and has a resistivity of at most 1015 ?·cm at 20° C. A method for production of glass is to produce the glass under such a condition that a redox represented by [Fe2+]/([Fe2+]+[Fe3+]) where Fe is present in the glass, is at least 0.6.

Abstract: Glass comprises essentially 20-70% SiO2, 10-50% TiO2+Nb2O5+SnO2+Ta2O5+WO3+CeO2, 0-50% MgO+CaO+SrO+BaO+ZnO, and 0-30% B2O3+Al2O3, in molar percentage terms based on the oxides; and has a resistivity of at most 1015 &OHgr;·cm at 20° C. A method for production of glass is to produce the glass under such a condition that a redox represented by [Fe2+]/([Fe2+]+[Fe3+]) where Fe is present in the glass, is at least 0.6.

Abstract: A crystallized glass for an optical filter substrate, which has an average linear expansion coefficient &agr;L of from 95×10−7/° C. to 130×10−7/° C. at from −30° C. to 70° C. and which has a crystal or the like of Na4-xKxAl4Si4O16 (1<x≦4) precipitated therein. Further, a crystallized glass for an optical filter substrate, which comprises from 35 to 60% of SiO2, from 10 to 30% of Al2O3, from 1 to 15% of TiO2+ZrO2, from 4 to 20% of Na2O, from 4 to 20% of K20, from 0.1 to 10% of CaO+SrO+Bao, from 0 to 10% of MgO, etc., and which has &agr;L of from 95×10−7/° C. to 130×10−7/° C. and which has a crystal or solid solution precipitated therein.

Abstract: A glass substrate for a display, which has a strain point of at least 550° C., an average linear expansion coefficient of from 65×10−7 to 100×10−7/°C. within a range of from 50 to 350° C. and a ratio KIC/d of at least 280 Pa·kg·m7/2 where KIC is the fracture toughness and d is the density.

Abstract: A glass for a substrate, having an average thermal expansion coefficient in the range of from 60×10−7 to 75×10−7/° C. at 50 to 350° C., which consists essentially of the following composition expressed by wt %: wt % SiO2 more than 62 to 74, Al2O3  1 to 15, MgO  0 to 9, CaO  0 to 14, Na2O  0 to 12, K2O  0 to 13, SiO2 + Al2O3 72 to 82, MgO + CaO  5 to 24, Na2O + K2O  1 to 15, MgO + CaO + Na2O + K2O 18 to 28.

Abstract: A glass for a substrate consisting essentially of: SiO2 45 to 65 wt %, Al2O3 6 to 20 wt %, B2O3 0.5 to 6 wt %, MgO 2 to 5 wt %, CaO 1 to 10 wt %, SrO 0 to 6.5 wt %, BaO 0 to 2 wt %, MgO + CaO + SrO + BaO 10 to 17 wt %, ZrO2 0 to 7 wt %, and Na2O + K2O 7 to 15 wt %.

Abstract: A plate glass containing B2O3, having a total content of Li2O, Na2O and K2O of from 0 to 13 mol %, a content of BaO of from 0 to 0.8 mol % and a content of SiO2 of from 50 to 75 mol %, and having an average linear thermal expansion coefficient of from 75×10−7 to 120×10−7/° C. in a range of from 50 to 350° C., a strain point of at least 550° C., a density of at most 2.65 g/cm3 at 20° C. and an oxygen atom density of from 7.2×10−2 to 9.0×10−2 mol/cm3 at 20° C.

Abstract: A glass composition for a substrate consisting essentially of from 56 to 72 wt % of SiO.sub.2, from 1 to less than 14 wt % of Al.sub.2 O.sub.3, from 0 to 9 wt % of MgO, from 0.5 to 11 wt % of CaO, from 0 to 4 wt % of SrO, from 0 to 3 wt % of BaO, from 6 to less than 14 wt % of MgO+CaO+SrO+BaO, from 0 to 9 wt % of Na.sub.2 O, from 6 to 20 wt % of K.sub.2 O, and from 6 to 20 wt % of Na.sub.2 O+K.sub.2 O.

Abstract: A glass substrate for magnetic disks, obtained by chemical strengthening treatment of a glass consisting essentially of from 50 to 65 wt % of SiO.sub.2, from 5 to 15 wt % of Al.sub.2 O.sub.3, from 2 to 7 wt % of Na.sub.2 O, from 4 to 9 wt % of K.sub.2 O, from 7 to 14 wt % of Na.sub.2 O+K.sub.2 O, from 12 to 25 wt % of MgO+CaO+SrO+BaO, and from 1 to 6 wt % of ZrO.sub.2.

Abstract: In each of the second and subsequent heat treatments, in a case where a glass substrate shrinks by heat treatment at the same average cooling rate as the average cooling rate in the immediately preceding heat treatment, the average cooling rate is set to be larger than that in the immediately preceding heat treatment, and inversely, in a case where the glass substrate extends, the average cooling rate is set to be smaller than that in the immediately preceding heat treatment.

Abstract: A glass composition for a substrate consisting essentially of from 59 to 72 wt % of SiO.sub.2, from 1 to 15 wt % of Al.sub.2 O.sub.3, from 0.5 to 9 wt % of MgO, from 0.5 to 11 wt % of CaO, from 0 to 6 wt % of SrO, from 0 to 5 wt % of BaO, from 4 to 19 wt % of MgO+CaO+SrO+BaO, from 0 to 9 wt % of Na.sub.2 O , from 4 to 21 wt % of K.sub.2 O, from 10 to 22 wt % of Na.sub.2 O+K.sub.2 O, and from 0.5 to 10.5 wt % of ZrO.sub.2, wherein the difference between the SiO.sub.2 content and the Al.sub.2 O.sub.3 content is from 50 to 71 wt %, and the specific gravity of the composition is less than 2.6.

Abstract: A glass composition for a substrate consisting essentially of from 52 to 62 wt % of SiO.sub.2, from 5 to 12 wt % of Al.sub.2 O.sub.3, from 0 to 4 wt % of MgO, from 3 to 5.5 wt % of CaO, from 6 to 9 wt % of SrO, from 0 to 13 wt % of BaO, from 17 to 27 wt % of MgO+CaO+SrO+BaO, from 7 to 14 wt % of Li.sub.2 O+Na.sub.2 O+K.sub.2 O, from 0.2 to 6 wt % of ZrO.sub.2, and from 0 to 0.6 wt % of SO.sub.3.

Abstract: A method for producing a glass-ceramic article, which comprises crystallizing a glass article consisting essentially of from 40 to 60% by weight of SiO.sub.2, from 13 to 19% by weight of Al.sub.2 O.sub.3, from 0 to 6% by weight of B.sub.2 O.sub.3, from 8 to 16% by weight of MgO, from 2 to 6% by weight of CaO, from 3 to 9% by weight of ZnO, from 5 to 12% by weight of TiO.sub.2, from 0 to 3% by weight of Li.sub.2 O+Na.sub.2 O+K.sub.2 O, from 0 to 3% by weight of P.sub.2 O.sub.5 and from 0 to 2% by weight of ZrO.sub.2.