Abstract: A glass for a magnetic recording medium substrate permitting the realization of a magnetic recording medium substrate affording good chemical durability and having an extremely flat surface, a magnetic recording medium substrate comprised of this glass, a magnetic recording medium equipped with this substrate, and methods of manufacturing the same. The glass compositions disclosed comprise oxides of at least Si, Al, Li, Na, K, Sn and Ce, optionally Sb, but not comprising As or F. Additional oxides of Mg, Cs, Sr and Ba may be present. The oxides are presented as molar percentages, mass percentages and ratios thereof.

Abstract: According to one aspect of the present invention, provided is glass for use in substrate for information recording medium, which comprises, denoted as molar percentages, a total of 70 to 85 percent of SiO2 and Al2O3, where SiO2 content is equal to or greater than 50 percent and Al2O3 content is equal to or greater than 3 percent; a total of equal to or greater than 10 percent of Li2O, Na2O and K2O; a total of 1 to 6 percent of CaO and MgO, where CaO content is greater than MgO content; a total of greater than 0 percent but equal to or lower than 4 percent of ZrO2, HfO2, Nb2O5, Ta2O5, La2O3 Y2O3 and TiO2; with the molar ratio of the total content of Li2O, Na2O and K2O to the total content of SiO2, Al2O3, ZrO2, HfO2, Nb2O5, Ta2O5, La2O3, Y2O3 and TiO2 ((Li2O+Na2O+K2O)/(SiO2+Al2O3+ZrO2+HfO2+Nb2O5+Ta2O5+La2O3+Y2O3+TiO2)) being equal to or less than 0.28.

Abstract: The provided are a glass for a magnetic recording medium substrate permitting the realization of a magnetic recording medium substrate affording good chemical durability and having an extremely flat surface, a magnetic recording medium substrate comprised of this glass, a magnetic recording medium equipped with this substrate, and methods of manufacturing the same. Glasses for a magnetic recording medium substrate are, glass I comprised of an oxide glass, comprising, denoted as mass percentages: Si 20 to 40 percent, Al 0.1 to 10 percent, Li 0.1 to 5 percent, Na 0.1 to 10 percent, K 0 to 5 percent (where the total content of Li, Na, and K is 15 percent or less), Sn 0.005 to 0.6 percent, and Ce 0 to 1.2 percent; the Sb content is 0 to 0.1 percent; and not comprising As or F; glass II comprised of oxide glass, comprising, as converted based on the oxide, denoted as molar percentages: SiO2 60 to 75 percent, Al2O3 1 to 15 percent, Li2O 0.1 to 20 percent, Na2O 0.

Abstract: A glass for a magnetic recording medium substrate permitting the realization of a magnetic recording medium substrate affording good chemical durability and having an extremely flat surface, a magnetic recording medium substrate comprised of this glass, a magnetic recording medium equipped with this substrate, and methods of manufacturing the same. The glass is an oxide glass not including As or F.

Abstract: A high-refractivity low-dispersion optical glass of which the Ta2O5 content is suppressed is provided, the optical glass comprising, by mass %, 1 to 30% of B2O3, 0.1 to 20% of SiO2, 55 to 75% of a total of La2O3, Gd2O3, Y2O3 and Yb2O3, the content of La2O3 being 15 to 55%, the mass ratio of the content of Gd2O3 to the total content of La2O3, Gd2O3, Y2O3 and Yb2O3, Gd2O3/La2O3+Gd2O3+Y2O3+Yb2O3), being 0.17 to 0.65, 0 to 13% of Ta2O5 (exclusive of 13%), and 0 to 25% of a total of Nb2O5, TiO2, WO3 and ZrO2, the content of Nb2O5 being less than 10%, and having a refractive index nd of 1.83 to 1.92 and an Abbe's number ?d of 36 to 45.

Abstract: According to one aspect of the present invention, provided is glass for use in substrate for information recording medium, which comprises, denoted as molar percentages, a total of 70 to 85 percent of SiO2 and Al2O3, where SiO2 content is equal to or greater than 50 percent and Al2O3 content is equal to or greater than 3 percent; a total of equal to or greater than 10 percent of Li2O, Na2O and K2O; a total of 1 to 6 percent of CaO and MgO, where CaO content is greater than MgO content; a total of greater than 0 percent but equal to or lower than 4 percent of ZrO2, HfO2, Nb2O5, Ta2O5, La2O3 Y2O3 and TiO2; with the molar ratio of the total content of Li2O, Na2O and K2O to the total content of SiO2, Al2O3, ZrO2, HfO2, Nb2O5, Ta2O5, La2O3, Y2O3 and TiO2 ((Li2O+Na2O+K2O)/(SiO2+Al2O3+ZrO2+HfO2+Nb2O5+Ta2O5+La2O3+Y2O3+TiO2)) being equal to or less than 0.28.

Abstract: According to one aspect of the present invention, provided is glass for use in substrate for information recording medium, which comprises, denoted as molar percentages, a total of 70 to 85 percent of SiO2 and Al2O3, where SiO2 content is equal to or greater than 50 percent and Al2O3 content is equal to or greater than 3 percent; a total of equal to or greater than 10 percent of Li2O, Na2O and K2O; a total of 1 to 6 percent of CaO and MgO, where CaO content is greater than MgO content; a total of greater than 0 percent but equal to or lower than 4 percent of ZrO2, HfO2, Nb2O5, Ta2O5, La2O3 Y2O3 and TiO2; with the molar ratio of the total content of Li2O, Na2O and K2O to the total content of SiO2, Al2O3, ZrO2, HfO2, Nb2O5, Ta2O5, La2O3, Y2O3 and TiO2 ((Li2O+Na2O+K2O)/(SiO2+Al2O3+ZrO2+HfO2+Nb2O5+Ta2O5+La2O3+Y2O3+TiO2)) being equal to or less than 0.28.

Abstract: A glass substrate for a display, which is formed of a glass having a light weight and having high refinability with decreasing environmental burdens, the glass comprising, by mass %, 50 to 70% of SiO2, 5 to 18% of B2O3, 10 to 25% of Al2O3, 0 to 10% of MgO, 0 to 20% of CaO, 0 to 20% of SrO, 0 to 10% of BaO, 5 to 20% of RO (in which R is at least one member selected from the group consisting of Mg, Ca, Sr and Ba), and over 0.20% but not more than 2.0% of R?2O (in which R? is at least one member selected from the group consisting of Li, Na and K), and containing, by mass %, 0.05 to 1.5% of oxide of metal that changes in valence number in a molten glass, and substantially containing none of As2O3, Sb2O3 and PbO.

Abstract: A method for manufacturing a disklike glass material comprising the successive molding of multiple pieces of disklike glass material from glass melt. Being suppressed variation over time in the concentration of infrared radiation-absorbing ions contained in the glass melt being molded into the pieces of disklike glass material so that the variation in the sheet thickness of the multiple pieces of disklike glass material falls within a range of ±15 percent of a reference value. The reference value being the median between the maximum value and the minimum value of the sheet thickness of 1,000 pieces of the glass material. In the course of molding multiple pieces of disklike glass material comprised of glass containing 0.1 to 100 ppm of infrared radiation-absorbing ions, vaiiation over time in the concentration of the infrared radiation-absorbing contained in the glass melt is suppressed to suppress variation in the sheet thickness of the multiple pieces of sheet like glass material.

Abstract: A glass substrate for a display, which is formed of a glass having a light weight and having high refinability with decreasing environmental burdens, the glass comprising, by mass %, 50 to 70% of SiO2, 5 to 18% of B2O3, 10 to 25% of Al2O3, 0 to 10% of MgO, 0 to 20% of CaO, 0 to 20% of SrO, 0 to 10% of BaO, 5 to 20% of RO (in which R is at least one member selected from the group consisting of Mg, Ca, Sr and Ba), and over 0.20% but not more than 2.0% of R?2O (in which R? is at least one member selected from the group consisting of Li, Na and K), and containing, by mass %, 0.05 to 1.5% of oxide of metal that changes in valence number in a molten glass, and substantially containing none of As2O3, Sb2O3 and PbO.

Abstract: An aspect of the present invention relates to glass for a magnetic recording medium substrate, which comprises, denoted as molar percentages, 50 to 75 percent of SiO2, 0 to 5 percent of Al2O3, 0 to 3 percent of Li2O, 0 to 5 percent of ZnO, a total of Na2O and K2O of 3 to 15 percent, a total of MgO, CaO, SrO, and BaO of 14 to 35 percent, a total of ZrO2, TiO2, La2O3, Y2O3, Yb2O3, Ta2O5, Nb2O5, and HfO2 of 2 to 9 percent, with a molar ratio of {(MgO+CaO)/(MgO+CaO+SrO+BaO)} falling within a range of 0.85 to 1, and a molar ratio of {Al2O3/(MgO+CaO)} falling within a range of 0 to 0.30.

Abstract: An optical glass comprising, by mass %, 12 to 30% of total of B2O3 and SiO2, 55 to 80% of total of La2O3, Gd2O3, Y2O3, Yb2O3, ZrO2, Nb2O5 and WO3, 2 to 10% of ZrO2, 0 to 15% of Nb2O5, 0 to 15% of ZnO and 0% or more but less than 13% of Ta2O5, wherein the ratio of the content of Ta2O5 to the total content of La2O3, Gd2O3, Y2O3, Yb2O3, ZrO2, Nb2O5 and WO3 is 0.23 or less, the ratio of the total content of La2O3, Gd2O3, Y2O3 and Yb2O3 to the total content of B2O3 and SiO2 is from 2 to 4, the optical glass having a refractive index nd of 1.86 or more and an Abbe's number ?d of 38 or more, and a rod-shaped glass shaped material and an optical element formed of the above optical glass each.

Abstract: The present invention relates to recording glass substrates molar percentages: 56-75 SiO2, 1-11 Al2O2, more than 0-4 Li2O, 1-15 Na2O. more than 0 less than 3 K2O, no BaO. total Li2O, Na2O and K2O 6-15, (Li2O Na2O) less than 0.50, {K2O/(Li2O, Na2O and K2O)} equal or less than 0.13, total MgO, CaO and SrO 10-30, MgO and CaO 10-30, {(MgO+CaO)/(MgO+CaO+SrO)} equal or more than 0.86, alkali oxides to alkaline earth oxides equal to or more than 0.50. total ZrO2, TiO2, Y2O3, La2O3, Gd2O3, Nb2O5, and Ta2O5 more than 0 equal to or less than 10, molar ratio {(ZrO2, TiO2, Y2O3, La2O3, Gd2O3, Nb2O5, and Ta2O5)/Al2O2 equal or more than 0.40, Tg equal to or higher than 600° C., average coefficient linear expansion equal or higher than 70×10?7/°C. at 100-300° C. and Young's modulus equal to or higher than 80 GPa.

Abstract: A glass substrate for a display, which is formed of a glass having a light weight and having high refinability with decreasing environmental burdens, the glass comprising, by mass %, 50 to 70% of SiO2, 5 to 18% of B2O3, 10 to 25% of Al2O3, 0 to 10% of MgO, 0 to 20% of CaO, 0 to 20% of SrO, 0 to 10% of BaO, 5 to 20% of RO (in which R is at least one member selected from the group consisting of Mg, Ca, Sr and Ba), and over 0.20% but not more than 2.0% of R?2O (in which R? is at least one member selected from the group consisting of Li, Na and K), and containing, by mass %, 0.05 to 1.5% of oxide of metal that changes in valence number in a molten glass, and substantially containing none of As2O3, Sb2O3 and PbO.

Abstract: According to one aspect of the present invention, provided is glass for use in substrate for information recording medium, which comprises, denoted as molar percentages, a total of 70 to 85 percent of SiO2 and Al2O3, where SiO2 content is equal to or greater than 50 percent and Al2O3 content is equal to or greater than 3 percent; a total of equal to or greater than 10 percent of Li2O, Na2O and K2O; a total of 1 to 6 percent of CaO and MgO, where CaO content is greater than MgO content; a total of greater than 0 percent but equal to or lower than 4 percent of ZrO2, HfO2, Nb2O5, Ta2O5, La2O3Y2O3 and TiO2; with the molar ratio of the total content of Li2O, Na2O and K2O to the total content of SiO2, Al2O3, ZrO2, HfO2, Nb2O5, Ta2O5, La2O3, Y2O3 and TiO2((Li2O+Na2O+K2O)/(SiO2+Al2O3+ZrO2+HfO2+Nb2O5+Ta2O5+La2O3+Y2O3+TiO2)) being equal to or less than 0.28.

Abstract: According to one aspect of the present invention, provided is glass for use in substrate for information recording medium, which comprises, denoted as molar percentages, a total of 70 to 85 percent of SiO2 and Al2O3, where SiO2 content is equal to or greater than 50 percent and Al2O3 content is equal to or greater than 3 percent; a total of equal to or greater than 10 percent of Li2O, Na2O and K2O; a total of 1 to 6 percent of CaO and MgO, where CaO content is greater than MgO content; a total of greater than 0 percent but equal to or lower than 4 percent of ZrO2, HfO2, Nb2O5, Ta2O5, La2O3 Y2O3 and TiO2; with the molar ratio of the total content of Li2O, Na2O and K2O to the total content of SiO2, Al2O3, ZrO2, HfO2, Nb2O5, Ta2O5, La2O3, Y2O3 and TiO2 ((Li2O+Na2O+K2O)/(SiO2+Al2O3+ZrO2+HfO2+Nb2O5+Ta2O5+La2O3+Y2O3+TiO2)) being equal to or less than 0.28.

Abstract: An optical glass comprising, by mass %, 12 to 30% of total of B2O3 and SiO2, 55 to 80% of total of La2O3, Gd2O3, Y2O3, Yb2O3, ZrO2, Nb2O5 and WO3, 2 to 10% of ZrO2, 0 to 15% of Nb2O5, 0 to 15% of ZnO and 0% or more but less than 13% of Ta2O5, wherein the ratio of the content of Ta2O5 to the total content of La2O3, Gd2O3, Y2O3, Yb2O3, ZrO2, Nb2O5 and WO3 is 0.23 or less, the ratio of the total content of La2O3, Gd2O3, Y2O3 and Yb2O3 to the total content of B2O3 and SiO2 is from 2 to 4, the optical glass having a refractive index nd of 1.86 or more and an Abbe's number ?d of 38 or more, and a rod-shaped glass shaped material and an optical element formed of the above optical glass each.

Abstract: An optical class comprising, by mass %, 12 to 30% of total of B2O3 and SiO2, 55 to 80% of total of La2O3, Gd2O3, Y2O3, ZrO2, Nb2O5 and WO3, 2 to 10% of ZrO2, 0 to 15% of Nb2O5, 0 to 15% of ZnO and 0% or more but less than 13% of Ta2O5, wherein the ratio of the content of Ta2O5 to the total content of La2O3, Gd2O3, Y2O3, Yb2O3, ZrO2, Nb2O5 and WO3 is 0.23 or less, the ratio of the total content of La2O3, Gd2O3, Y2O3 and Yb2O3 to the total content of B2O3 and SiO2 is from 2 to 4, the optical glass having a refractive index nd of 1.86 or more and an Abbe's number ?d of 38 or more, and a rod shaped glass shaped material and an optical element formed of the above optical glass each.

Abstract: An aspect of the present invention relates to a glass substrate for a magnetic recording medium, which is comprised of glass comprising, denoted as molar percentages, 56 to 75 percent of SiO2, 1 to 11 percent of Al2O3, more than 0 percent but equal to or less than 4 percent of Li2O, equal to or more than 1 percent but less than 15 percent of Na2O, equal to or more than 0 percent but less than 3 percent of K2O, and substantially no BaO, with a total content of Li2O, Na2O, and K2O falling within a range of 6 to 15 percent, with a molar ratio (Li2O/Na2O) being less than 0.50, with a molar ratio {K2O/(Li2O+Na2O+K2O)} being equal to or less than 0.13, with a total content of MgO, CaO, and SrO falling within a range of 10 to 30 percent, with a total content of MgO and CaO falling within a range of 10 to 30 percent, with a molar ratio {(MgO+CaO)/(MgO+CaO+SrO)} being equal to or more than 0.

Abstract: According to one aspect of the present invention, provided is glass for use in substrate for information recording medium, which comprises, denoted as molar percentages, a total of 70 to 85 percent of SiO2 and Al2O3, where SiO2 content is equal to or greater than 50 percent and Al2O3 content is equal to or greater than 3 percent; a total of equal to or greater than 10 percent of Li2O, Na2O and K2O; a total of 1 to 6 percent of CaO and MgO, where CaO content is greater than MgO content; a total of greater than 0 percent but equal to or lower than 4 percent of ZrO2, HfO2, Nb2O5, Ta2O5, La2O3 Y2O3 and TiO2; with the molar ratio of the total content of Li2O, Na2O and K2O to the total content of SiO2, Al2O3, ZrO2, HfO2, Nb2O5, Ta2O5, La2O3, Y2O3 and TiO2 ((Li2O+Na2O+K2O)/(SiO2+Al2O3+ZrO2+HfO2+Nb2O5+Ta2O5+La2O3+Y2O3+TiO2)) being equal to or less than 0.28.