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: The present invention provide a fluorophosphate glass comprising 3 to 25 cation % of P5+, more than 30 cation % and 40 cation % or less of Al3+, 0.5 to 20 cation % of Li+ and 65 anion % or more of F? as glass ingredients, and having a liquid phase temperature of 700° C. or less. The fluorophosphate glass of the present invention has ultra low dispersibility and stability, and is preferably used for glass materials for press molding, optical element blanks and optical elements.

Abstract: An information recording medium is prepared by forming a multi-layered film, including an information recording layer, on a substrate by transferring the substrate heated at an average heating rate of at least 10° C./second in a heating zone, along consecutive film-forming zones, and consecutively forming layers forming the multi-layered film in the film-forming zones.

Abstract: A glass for use in chemical reinforcement for use in a substrate of an information recording medium, having a composition comprising, denoted as mol %: SiO2 47 to 70%? Al2O3 1 to 10% (where the total of SiO2 and Al2O3 is 57 to 80%) CaO 2 to 25% BaO 1 to 15% Na2O 1 to 10% K2O 0 to 15% (where the total of Na2O and K2O is 3 to 16%) ZrO2 1 to 12% MgO 0 to 10% SrO 0 to 15% (where the ratio of the content of CaO to the total of MgO, CaO, SrO, and BaO is greater than or equal to 0.5) ZnO 0 to 10% (where the total of MgO, CaO, SrO, BaO, and ZnO is 3 to 30%) TiO2 0 to 10% and the total content of the above-stated components is greater than or equal to 95%. A glass for use in chemical reinforcement for use in the substrate of an information recording medium employed in a perpendicular magnetic recording system, in which the glass exhibits the glass transition temperature is greater than or equal to 600° C.

Abstract: A glass for use in chemical reinforcement for use in a substrate of an information recording medium, having a composition comprising, denoted as mol %: SiO2 47 to 70%? Al2O3 1 to 10% (where the total of SiO2 and Al2O3 is 57 to 80%) CaO 2 to 25% BaO 1 to 15% Na2O 1 to 10% K2O 0 to 15% (where the total of Na2O and K2O is 3 to 16%) ZrO2 1 to 12% MgO 0 to 10% SrO 0 to 15% (where the ratio of the content of CaO to the total of MgO, CaO, SrO, and BaO is greater than or equal to 0.5) ZnO 0 to 10% (where the total of MgO, CaO, SrO, BaO, and ZnO is 3 to 30%) TiO2 0 to 10% and the total content of the above-stated components is greater than or equal to 95%.

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: Disclosed are a glass substrate for an information recording medium, having excellent scratch resistance and a light weight and having high fracture toughness, the glass substrate having a fragility index value, measured in water, of 12 ?m?1/2 or less or having a fragility index value, measured in an atmosphere having a dew point of ?5° C. or lower, of 7 ?m?1/2 or less, or the glass substrate comprising, by mol %, 40 to 75% of SiO2, 2 to 45% of B2O3 and/or Al2O3 and 0 to 40% of R?2O in which R? is at least one member selected from the group consisting of Li, Na and K), wherein the total content of SiO2, B2O3, Al2O3 and R?2O is at least 90 mol %, and a magnetic information recording medium comprising a magnetic recording layer formed on the glass substrate.

Abstract: Provided is a low-dispersion optical glass that is formed of a fluorophosphate glass in which the molar ratio of the content of O2? to the content of P5+, O2?/P5+, is 3.5 or more and that has an Abbe's number (?d) of over 70 or has an F? content of 65 anionic % or more, and the optical glass enables the suppression of the volatilization of a glass component when an optical glass formed of a fluorophosphate glass is produced or when an obtained glass in a molten state is caused to flow out to shape it into a glass shaped material, so that the variation of properties such as a refractive index, etc., involved in the fluctuations of a glass composition and the variation of quality such as the occurrence of striae can be suppressed.

Abstract: The optical glass has a refractive index of equal to or greater than 1.65 and an Abbé number ranging from 50 to 60. In the optical glass, as molar basis, a ratio of SiO2 content to B2O3 content is greater than 0.5 and equal to or less than 0.90; a total content of SiO2 and B2O3 ranges from 50 to 70 percent; Li2O content ranges from 5 to 20 percent; La2O3 content ranges from 0.5 to 22 percent; a ratio of ZnO content to RO (MgO, CaO, SrO and BaO) is equal to or greater than 0.5; a total content of Gd2O3, Y2O3 and Yb2O3 ranges from 1 to 15 percent; Sb2O3 content ranges from 0 to 1 percent; and no BaO is comprised, or a ratio of the total content of La2O3, Gd2O3, Y2O3 and Yb2O3 to the content of BaO is equal to or greater than 10.

Abstract: A fluorophosphate glass having a fluorine content of 25% or more by anionic %, which is produced from a glass raw material containing 0.1 to 0.5%, by anionic %, of a halide containing a halogen element selected from chlorine, bromine or iodine, and a phosphate glass having a fluorine content of less than 25% by anionic %, which is produced from a glass raw material containing 0.1 to 5% by anionic %, of a halide containing a halogen element selected from chlorine, bromine or iodine.

Abstract: A fluorophosphate glass containing: P5+ in an amount of 20 to 45 cationic %; Al3+ in an amount of 15 to 35 cationic %; Ba2+ in an amount of 20 to 50 cationic %; F? in an amount of 20 to 50 anionic %; and O2? in an amount of 50 to 80 anionic %. A molar ratio of O2?/P5+ is larger than or equal to 3.5. In addition, a molar ratio of Al3+/P5+ is larger than or equal to 0.45. Furthermore, the Abbe number (?d) of the glass is larger than or equal to 66. Finally a refractive index (nd) of the glass satisfies an expression (1): nd?2.0614?0.0071×?d.

Abstract: A substrate for an information recording medium, which has high heat resistance and high acid resistance and is formed of a glass having a glass transition temperature (Tg) of 600° C. or higher and having an etching rate of 0.1 ?m/minute or less with regard to a hydrosilicofluoric acid aqueous solution that is maintained at a temperature of 45° C. and has a hydrosilicofluoric acid concentration of 1.72% by weight, and an information recording medium having an information recording layer formed on the above substrate.

Abstract: The present invention provides a fluorophosphate glass containing more than 3 cationic % and 30 cationic % or less of a phosphorus ingredient in terms of P5+, the glass having a ratio I(1)/I(0) of equal to or less than 0.08 in which I(0) is a strength of a resonance peak generated near a reference frequency of 31P in a nuclear magnetic resonance spectrum and I(1) is a strength of a first-order side band peak of the resonance peak. The glass of the invention is reduced in volatility and erosiveness.

Abstract: The present invention provides a fluorophosphate glass containing phosphorus, oxygen and fluorine as glass ingredients, in which, provided that a refractive index nd of the glass is nd(1) and a refractive index nd after re-melting the glass at 900° C. for 1 hour in a nitrogen atmosphere, cooling the glass to a glass transition temperature and then cooling the glass down to 25° C. at a temperature decrease rate of 30° C. per hour is nd(2), an absolute value of a difference between nd(1) and nd(2) (nd(2)-nd(1)) is equal to or less than 0.00300, and a molar ratio (O2?/P5+) of a content of O2? to a content of P5+ is equal to or more than 3.5. The glass of the invention is reduced in volatility and erosiveness.

Abstract: The present invention provides a fluorophosphate glass containing 30 to 50 cationic % of a phosphorus ingredient in terms of P5+, the glass having, in a nuclear magnetic resonance spectrum, a resonance spectrum which is generated near a reference frequency of 31P and has a shape of Gaussian function. The glass of the invention is reduced in volatility and erosiveness.

Abstract: A glass substrate for an information recording medium, which has high heat resistance, has such high thermal shock resistance that it does not break when exposed to a sharp change in temperature and has high strength against scratching, and which is formed of a glass comprising SiO2, Al2O3, ZrO2, CaO, BaO, Li2O and Na2O as essential components and comprises, by mole %, 50 to 70% of SiO2, 1 to 10% of Al2O3, over 0% but not more than 12% of ZrO2, 2 to 24% of CaO, over 0% but not more than 15% of BaO, 0 to 10% of MgO, 0 to 15% of SrO, provided that the content of CaO+BaO+MgO+SrO is over 10% but less than 25%, over 0% but not more than 6% of Li2O, over 0% but not more than 10% of Na2O, 0 to 5% of K2O, and 0 to 10% of TiO2.

Abstract: A low-dispersion optical glass suitable for producing a quality preform from a molten glass and suitable for precision press-molding, which is a fluorophosphate glass containing, as essential cationic components, P5+, Al3+, at least two members selected from Mg2+, Ca2+, Sr2+ and Ba2+ as divalent cationic components (R2+) and Li+ and containing, by cationic %, 10 to 45% of P5+, 5 to 30% of Al3+, 0 to 20% of Mg2+, 0 to 25% of Ca2+, 0 to 30% of Sr2+, 0 to 33% of Ba2+, 1 to 30% of Li+, 0 to 10% of Na+, 0 to 10% of K+, 0 to 5% of Y3+, and 0 to 15% of B3+, the molar ratio of the content of F? to the total content of F? and O2?, F?/(F?+O2?), being 0.25 to 0.85, the optical glass having a refractive index (Nd) of 1.40 to 1.58 and an Abbe's number (?d) of 67 to 90.

Abstract: Disclosed are a glass substrate for an information recording medium, having excellent scratch resistance and a light weight and having high fracture toughness, the glass substrate having a fragility index value, measured in water, of 12 ?m?1/2 or less or having a fragility index value, measured in an atmosphere having a dew point of ?5° C. or lower, of 7 ?m?1/2 or less, or the glass substrate comprising, by mol %, 40 to 75% of SiO2, 2 to 45% of B2O3 and/or Al2O3 and 0 to 40% of R?2O in which R? is at least one member selected from the group consisting of Li, Na and K), wherein the total content of SiO2, B2O3, Al2O3 and R?2O is at least 90 mol %, and a magnetic information recording medium comprising a magnetic recording layer formed on the glass substrate.

Abstract: A substrate for an information recording medium, which substrate is made of a highly heat-resistant and low-alkali-elution glass and is suitable as a substrate for forming a perpendicular-magnetic-recording-mode layers thereon at a high temperature with a sputtering machine, the substrate being made of an alkali-metal-oxide-containing glass having a glass transition temperature (Tg) of 620° C. or higher and satisfying a requirement that the alkali ion elution amount per a unit area when the glass is immersed in water having a temperature of 80° C. for 24 hours is 0.2 ?mol/cm2 or less, an information recording medium having an information recording layer formed on the substrate, and a process for producing the information recording medium.