Abstract: Provided is an optical glass containing glass-forming cations, the optical glass satisfying, expressed in cation percent, 10 cat %?B3+?50 cat %, 15 cat %?La3+?35 cat %, 20 cat %?Nb5+?50 cat %, and 15 cat %?Ti4+?25 cat %.

Abstract: Provided is a glass which contains, by mass %, the following components: 20 to 35% of SiO2 and B2O3 in total, 50 to 70% of La2O3, Gd2O3, Y2O3 and Yb2O3 in total, 37 to 69% of La2O3, 0 to 3% of Gd2O3, 3 to 30% of Y2O3, 0% or more but less than 2% of Yb2O3, 2 to 15% of ZrO2, 1 to 6% of TiO2, Nb2O5 and Ta2O5 in total, 0 to 4% of ZnO, and 0 to 2% of WO3, wherein a mass ratio ZnO/Nb2O5 is in a range of 0 to 1.0 but Nb2O5 is contained as an essential component, a refractive index nd is in a range of 1.790 to 1.830, and an Abbe's number vd is in a range of 45 to 48.

Abstract: An optical Glass characterized by comprising, denoted as molar percentages: B2O5—5 to 45 percent; SiO2—0 to 6 percent (excluding 6 percent); Li2O, Na2O, K2O in total—0 to 3 percent; ZnO—10 to 40 percent; La2O3. 5 to 30 percent; Gd2O3—1 to 20 percent; and ZrO2, TaO2, TiO2, Nb2O5, WO3, and Bi2O3 in total—2.5 to 20 percent. The cation ratio of the Ti4+ content relative to the total content of Zr4+, Ta5+, Ti4+, Nb5+, W6+, and Bi3+ is 0.30 or lower; in that the temperature Tp at which a viscosity of 107.2 dPa·s is exhibited is 706° C. or lower. The refractive index nd and the Abbé number v(nu)d satisfy all of the following relations (I) to (IV): 34.0?vd<40 (I); nd?1.87 (II); nd?2.245?0.01×vd (III) and nd?2.28?0.01×vd (IV).

Abstract: The invention provides an optical glass for press molding which can satisfy all of the following requirements: (1) it contains no environmentally undesirable components; (2) it can easily achieve a low glass transition point; (3) it has a high refractive index and high dispersion; (4) it can easily provide a glass having an excellent visible light transmittance; and (5) it has excellent resistance to devitrification during preparation of a preform. The optical glass for press molding has a refractive index nd of 1.925 or more, an Abbe's number ?d of 10 to 30, and a glass composition, in % by mass, of 20 to 80% Bi2O3, 10 to 30% B2O3, and 0 to 5.5% GeO2 and is substantially free of lead component, arsenic component, and F component.

Abstract: The present invention relates to an optical glass including, in terms of mass % on the basis of oxides, B2O3: 10% to 20%, SiO2: 0.5% to 12%, ZnO: 5% to 19%, Ta2O5: 3% to 17%, Li2O: 0.2% to 3%, ZrO2: 0.6% to 4.9%, WO3: 6.1% to 20%, La2O3: 32.5% to 50%, and Y2O3: 0.2% or more and less than 1.5%, in which a mass fraction (La2O3/Y2O3) of a content of La2O3 to a content of Y2O3 in terms of mass % is 40 or higher, and the optical glass has optical constants of a refractive index nd of 1.83 to 1.88 and an Abbe's number ?d of 39 to 42.

Abstract: An aspect of the present invention relates to optical glass, which is oxide glass comprising various cationic components in prescribed amounts without Pb, with a refractive index nd of 1.750 to 1.850, an Abbé number ?d of 29.0 to 40.0, and a glass transition temperature of less than 630° C.

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: Provided is an optical glass which can satisfy all of the following requirements: (1) it contains no environmentally undesirable components; (2) it can easily achieve a low glass transition point; (3) it has a high refractive index and high dispersion; (4) it can easily provide a glass having a superior visible light transmittance; and (5) it has superior resistance to devitrification during preparation of a preform. The optical glass has a refractive index nd of 2.0 or more, an Abbe's number ?d of 20 or less, a glass transition point of 450° C. or below, and a glass composition, in % by mass, of 70 to 90% Bi2O2, 4 to 29.9% B2O2, 0.1 to 10% Li2O+Na2O+K2O, and 0 to 2.5% SiO2+Al2O2 and is substantially free of lead component, arsenic component, F component, TeO2, and GeO2.

Abstract: An optical glass including B3+, La3+ and Nb5+ as cationic components constituting the glass, wherein the optical glass satisfies the following expressions represented in cation percentages: 10 cat. %?B3+?50 cat. %; 40 cat. %?La3+?65 cat. %; 0 cat. %?Nb5+?40 cat. %; 80 cat. %?(total amount of B3++La3++Nb5+)?100 cat. %; and 0 cat. %?Si4+?10 cat. %; 0 cat. %?Ge4+?5 cat. %; 0 cat. %?Mg2+?5 cat. %; 0 cat. %?Ba2+?10 cat. %; 0 cat. %?Ca2+?10 cat. %; 0 cat. %?Sr2+?10 cat. %; 0 cat. %?Zn2+?20 cat. %; 0 cat. %?W6+?5 cat. %; 0 cat. %?Zr4+?5 cat. %; 0 cat. %?Ti4+?5 cat. %; 0 cat. %?Bi3+?5 cat. %; 0 cat. %?Ta5+?10 cat. %; 0 cat. %?(total amount of Y3++Gd3+)?20 cat. %; and 0 cat. %?(total amount of Yb3++Lu3+)?10 cat. %.

Abstract: An optical glass having a refractive index nd of 1.70 or greater and an Abbé number of 50 or greater. Given as mole percentages, it comprises: B2O3 (20 to 80 percent), SiO2 (0 to 30 percent), Li2O (1 to 25 percent), ZnO (0 to 20 percent), La2O3 (4 to 30 percent), Gd2O3 (1 to 25 percent), Y2O3 (0 to 20 percent), ZrO2 (0 to 5 percent), MgO (0 to 25 percent), CaO (0 to 15 percent), and SrO (0 to 10 percent), with the combined quantity of the above components being 97 percent or greater. The molar ratio of {ZnO/(La2O3+Gd2O3+Y2O3)} is 0.8 or less and the molar ratio of {(CaO+SrO+BaO)/(La2O3+Gd2O3+Y2O3)} is 0.8 or less. Ta2O5 may be incorporated as an optional component, with the molar ratio {(ZrO2+Ta2O5)/(La2O3+Gd2O3+Y2O3)} being 0.4 or less.

Abstract: A high-refractivity low-dispersion optical glass that can be stably supplied and has excellent glass stability and that has coloring reduced, composed of in mass %, 5 to 32% of total of SiO2 and B2O2, 45 to 65% of total of La2O2, Gd2O2 and Y2O2, 0.5 to 10% of ZnO, 1 to 20% of total of TiO2 and Nb2O5, and optionally other components. The optical glass has a refractive index nd of 1.89 to 2.0, an Abbe's number ?d of 32 to 38 and a coloring degree ?70 of 430 nm or less.

Abstract: An optical glass having high-refractivity and low-dispersion properties and containing, by mol %, 0.1 to 40% of SiO2, 10 to 50% of B2O3, wherein the mass ratio of the content of SiO2 to the content of B2O3, SiO2/B2O3, is 1 or less, 0.5 to 22% of ZnO, 5 to 50% of La2O3, and optionally other ingredients. The optical glass has a refractive index nd of 1.86 to 1.95 and an Abbe's number ?d of (2.36?nd)/0.014 or more but less than 38, and a glass transition temperature of equal to or greater than 640° C.

Abstract: An optical glass that is an oxide glass having a very high refractive index in spite of its low-dispersion property, having excellent glass stability and having less susceptibility to coloring.

Abstract: The invention provides an optical glass for press molding which can satisfy all of the following requirements: (1) it contains no environmentally undesirable components; (2) it can easily achieve a low glass transition point; (3) it has a high refractive index and high dispersion; (4) it can easily provide a glass having an excellent visible light transmittance; and (5) it has excellent resistance to devitrification during preparation of a preform. The optical glass for press molding has a refractive index nd of 1.925 or more, an Abbe's number ?d of 10 to 30, and a glass composition, in % by mass, of 20 to 80% Bi2O3, 10 to 30% B2O3, and 0 to 5.5% GeO2 and is substantially free of lead component, arsenic component, and F component.

Abstract: The present invention relates to an optical glass having a refractive index nd of 1.86 or higher and an Abbé number v(nu)d of 28 to 36; a preform for precision press molding and an optical element that are comprised of this glass; and a method for manufacturing the optical element.

Abstract: The present invention relates to an optical glass with a refractive index nd of 1.89 or higher and an Abbé number v(nu)d of 28 to 36; a preform for precision press molding and an optical element that are comprised of this glass; and a method for manufacturing the optical element.

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 invention provides a novel optical glass which has a refractive index (nd) of 1.78 to 2.2 and an Abbe value (?d) of 16 to less than 40 and is suitable for precision mold press molding by virtue of its having a low glass transition temperature, namely, an optical glass which contains by mole in terms of oxides 25 to 60% B2O3, 2 to 45% (in total) TiO2 and Nb2O5 and 1 to 25% WO3 and has a refractive index (nd) of 1.78 to 2.2 and an Abbe value (?d) of 16 to less than 40. Further, the glass contains 5 to 35% La2O3 and 1 to 40% ZnO and has a glass transition temperature (Tg) of 700° C. or below. The optical glass is excellent in meltability, stability and devitrification resistance and has a high refractive index, high light-dispersive power and excellent precision press moldability.

Abstract: There is provided a glass composition having a devitrification temperature of 1000° C. or below, a glass transformation temperature (Tg) of 535° C. or below and a specific gravity within a range from 3 to 4. The glass composition has a refractive index (nd) within a range from 1.60 to 1.75 and an Abbe number (?d) within a range from 50 to 60.

Abstract: A high-refractivity low-dispersion optical glass that can be stably supplied and has excellent glass stability and that has coloring reduced, composed of in mass %, 5 to 32% of total of SiO2 and B2O3, 45 to 65% of total of La2O3, Gd2O3 and Y2O3, 0.5 to 10% of ZnO, 1 to 20% of total of TiO2 and Nb2O5, and optionally other components. The optical glass has a refractive index nd of 1.89 to 2.0, an Abbe's number ?d of 32 to 38 and a coloring degree ?70 of 430 nm or less.

Abstract: Provided is an optical glass having homogeneous optical characteristics such that striae and devitrification hardly occur at the time of producing a gob. The optical glass includes cationic components having the following composition, provided that a total of the cationic components is 95 cat %, and has a refractive index (nd) of 1.6 or more and less than 1.7 and an Abbe number (vd) of 50 or more and 56 or less, Si4+ 3 cat % or more and 13 cat % or less B3+ 40 cat % or more and 55 cat % or less La3+ 4 cat % or more and 9 cat % or less Ca2+ 6 cat % or more and 12 cat % or less Li+ 11 cat % or more and 18 cat % or less Zn2+ 6 cat % or more and 12 cat % or less Zr4+ 1 cat % or more and 4 cat % or less provided that Si4+/B3+ is 0.05 or more and 0.3 or less, and Li+/Zn2+ is 1.3 or more and 2.0 or less.

Abstract: An optical glass that is an oxide glass having a very high refractive index in spite of its low-dispersion property, having excellent glass stability and having less susceptibility to coloring.

Abstract: The optical glass has a refractive index nd of 1.945?nd?1.97, an Abbe number ?d of 33??d?36, and a composition with the following components in amounts expressed in % of their cations, with respect to the total number of cations in the composition: B3+, 35-46; La3+, 25-35; Ta5+, 6-14; W6+, 6-13; Zr4+, 1-7; Gd3+, 0-5; Nb5+, 0-4; Y+3, 0-4; Ba2+, 0-2; ? alkaline earth metal cations, 0-2, ? La3++Ta3++W6++Zr4++Gd3++Nb5++Y3+?50; and at least one fining agent, 0-0.3. Also a ratio of B3+ to La+3 is 1.1 to 1.6 and a ratio of B3+ to ? Si+4+B3+ is ?0.5. The glass is free of lead, arsenic, Ti4+, Th4+, Zn2+, F?, and Hf+4.

Abstract: An optical glass comprising, by mol %, 0.1 to 40% of SiO2, 10 to 50% of B2O3, 0 to 10% of total of Li2O, Na2O and K2O, 0 to 10% of total of MgO, CaO, SrO and BaO, 0.5 to 22% of ZnO, 5 to 50% of La2O3, 0.1 to 25% of Gd2O3, 0.1 to 20% of Y2O3, 0 to 20% of Yb2O3, 0 to 25% of ZrO2, 0 to 25% of TiO2, 0 to 20% of Nb2O5, 0 to 10% of Ta2O5, over 0.1% but not more than 20% of WO3, 0 to less than 3% of GeO2, 0 to 10% of Bi2O3, and 0 to 10% of Al2O3, the mass ratio of the content of SiO2 to the content of B2O3, SiO2/B2O3, being 1 or less, the optical glass having a refractive index nd of 1.86 to 1.95 and an Abbe's number ?d of (2.36?nd)/0.014 or more but less than 38.

Abstract: Provided is an optical glass which can satisfy all of the following requirements: (1) it contains no environmentally undesirable components; (2) it can easily achieve a low glass transition point; (3) it has a high refractive index and high dispersion; (4) it can easily provide a glass having a superior visible light transmittance; and (5) it has superior resistance to devitrification during preparation of a preform. The optical glass has a refractive index nd of 2.0 or more, an Abbe's number vd of 20 or less, a glass transition point of 450° C. or below, and a glass composition, in % by mass, of 70 to 90% Bi2O2, 4 to 29.9% B2O2, 0.1 to 10% Li2O+Na2O+K2O, and 0 to 2.5% SiO2+Al2O2 and is substantially free of lead component, arsenic component, F component, TeO2, and GeO2.

Abstract: An optical glass that is an oxide glass having a very high refractive index in spite of its low-dispersion property, having excellent glass stability and having less susceptibility to coloring.

Abstract: An optical Glass characterized by comprising, denoted as molar percentages: B2O5—5 to 45 percent; SiO2—0 to 6 percent (excluding 6 percent); Li2O, Na2O, K2O in total—0 to 3 percent; ZnO—10 to 40 percent; La2O3. 5 to 30 percent; Gd2O3—1 to 20 percent; and ZrO2, TaO2, TiO2, Nb2O5, WO3, and Bi2O3 in total—2.5 to 20 percent. The cation ratio of the Ti4+ content relative to the total content of Zr4+, Ta5+, Ti4+, Nb5+, W6+, and Bi3+ is 0.30 or lower; in that the temperature Tp at which a viscosity of 107.2 dPa·s is exhibited is 706° C. or lower. The refractive index nd and the Abbé number v(nu)d satisfy all of the following relations (I) to (IV): 34.0?vd<40 (I); nd?1.87 (II); nd?2.245?0.01×vd (III) and nd?2.28?0.01×vd (IV).

Abstract: The lead-free and arsenic-free optical glasses have a refractive index of 1.83?nd?1.95 and an Abbé number of 24??d?35, good chemical resistance, excellent crystallization stability and a composition, in wt. % based on oxide content, of SiO2, 2-8; B2O3, 15-22; La2O3, 35-42; ZnO, 10-18; TiO2, 9-15; ZrO2, 3-10; Nb2O5, 4-10; and WO3, >0.5-3. Besides containing at most 5 wt. % of each of GeO2, Ag2O and BaO and conventional fining agents, they may also contain at most in total 5 wt. % of Al2O3, MgO, CaO, SrO, P2O5 and up to at most in total 5 wt. % of the components F, Ta2O5. The glasses are preferably free of alkali metal oxides, Bi2O3, Y2O3, Gd2O3 and/or Yb2O3. Optical elements made from the optical glass are also described.

Abstract: An object of the present invention is to provide optical glass having improved glass-devitrification resistance and moldability without causing reduction in refractive index, and also provide an optical element using the optical glass as a raw material. Specifically, the present invention provides an optical glass containing components of, by mol %: B2O3: over 60% through 75%; Bi2O3: 24% to 39%; La2O3: 7% or lower; Gd2O3: 7% or lower; and ZrO2: 7% or lower.

Abstract: The present invention relates to an optical glass containing, in terms of mass % on the basis of oxides, B2O3: 10 to 20%, SiO2: 0.5 to 12%, ZnO: 5 to 19%, Ta2O5: 2.5 to 17%, Li2O: 0.2 to 3%, ZrO2: 0.6 to 4.9%, WO3: 1 to 20%, La2O3: 25 to 50%, Gd2O3: 0 to 13%, and Y2O3: 0.2 to 20%, provided that La2O3+Gd2O3+Y2O3 is 35 to 60%, in which the optical glass does not substantially contain Nb2O5, and has a refractive index (nd) of 1.82 to 1.86, an Abbe's number (?d) of 37 to 44 and a glass transition point (Tg) of 630° C. or lower.

Abstract: An optical glass having a refractive index nd of 1.70 or greater and an Abbé number of 50 or greater. Given as mole percentages, it comprises: B2O3 (20 to 80 percent), SiO2 (0 to 30 percent), Li2O (1 to 25 percent), ZnO (0 to 20 percent), La2O3 (4 to 30 percent), Gd2O3 (1 to 25 percent), Y2O3 (0 to 20 percent), ZrO2 (0 to 5 percent), MgO (0 to 25 percent), CaO (0 to 15 percent), and SrO (0 to 10 percent), with the combined quantity of the above components being 97 percent or greater. The molar ratio of {ZnO/(La2O3+Gd2O3+Y2O3)} is 0.8 or less and the molar ratio of {(CaO+SrO+BaO)/(La2O3+Gd2O3+Y2O3)} is 0.8 or less. Ta2O5 may be incorporated as an optional component, with the molar ratio {(ZrO2+Ta2O5)/(La2O3+Gd2O3+Y2O3)} being 0.4 or less.

Abstract: An object of the invention is to provide an optical glass for precision press having optical properties of a high refractive index and a low dispersion property and having a low molding temperature, a high devitrification resistance, an excellent molding property, and a small specific gravity. The optical glass of the invention contains, in terms of % by mass on the basis of oxides, respective components of B2O3: 10 to 20%, SiO2: 0.5 to 12%, La2O3: 25 to 50%, Gd2O3: 0 to 20%, Y2O3: 0 to 20%, provided that La2O3+Gd2O3+Y2O3: 35 to 60%, ZnO: 5 to 20%, Li2O: 0.2 to 3%, ZrO2: 0 to 0.5%, Ta2O5: 3 to 18% and WO3: 3 to 20%, and has optical constants of a refractive index nd of 1.84 to 1.86 and an Abbe number vd of 37 to 42 and a glass transition point (Tg) of 630° C. or lower.

Abstract: An optical glass having a refractive index nd of 1.70 or greater and an Abbé number of 50 or greater. Given as mole percentages, it comprises: B2O3 (20 to 80 percent), SiO2 (0 to 30 percent), Li2O (1 to 25 percent), ZnO (0 to 20 percent), La2O3 (4 to 30 percent), Gd2O3 (1 to 25 percent), Y2O3 (0 to 20 percent), ZrO2 (0 to 5 percent), MgO (0 to 25 percent), CaO (0 to 15 percent), and SrO (0 to 10 percent), with the combined quantity of the above components being 97 percent or greater. The molar ratio of {ZnO/(La2O3+Gd2O3+Y2O3)} is 0.8 or less and the molar ratio of {(CaO+SrO+BaO)/(La2O3+Gd2O3+Y2O3)} is 0.8 or less. Ta2O5 may be incorporated as an optional component, with the molar ratio {(ZrO2+Ta2O5)/(La2O3+Gd2O3+Y2O3)} being 0.4 or less.

Abstract: An optical Glass characterized by comprising, denoted as molar percentages: B2O5—5 to 45 percent; SiO2—0 to 6 percent (excluding 6 percent); Li2O, Na2O, K2O in total—0 to 3 percent; ZnO—10 to 40 percent; La2O3—5 to 30 percent; Gd2O3—1 to 20 percent; and ZrO2, TaO2, TiO2, Nb2O5, WO3, and Bi2O3 in total—2.5 to 20 percent. The cation ratio of the Ti4+ content relative to the total content of Zr4+, Ta5+, Ti4+, Nb5+, W6+, and Bi3+ is 0.30 or lower; in that the temperature Tp at which a viscosity of 107.2 dPa·s is exhibited is 706° C. or lower. The refractive index nd and the Abbé number v(nu)d satisfy all of the following relations (I) to (IV): 34.0?vd<40 (I); nd?1.87 (II); nd?2.245?0.01×vd (III) and nd?2.28?0.01×vd (IV).

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 glass having a refractive index nd of 1.70 or greater and an Abbé number of 50 or greater. Given as mole percentages, it comprises: B2O3 (20 to 80 percent), SiO2 (0 to 30 percent), Li2O (1 to 25 percent), ZnO (0 to 20 percent), La2O3 (4 to 30 percent), Gd2O3 (1 to 25 percent), Y2O3 (0 to 20 percent), ZrO2 (0 to 5 percent), MgO (0 to 25 percent), CaO (0 to 15 percent), and SrO (0 to 10 percent), with the combined quantity of the above components being 97 percent or greater. The molar ratio of {ZnO/(La2O3+Gd2O3+Y2O3)} is 0.8 or less and the molar ratio of {(CaO+SrO+BaO)/(La2O3+Gd2O3+Y2O3)} is 0.8 or less. Ta2O5 may be incorporated as an optional component, with the molar ratio {(ZrO2+Ta2O5)/(La2O3+Gd2O3+Y2O3)} being 0.4 or less.

Abstract: An aspect of the present invention relates to optical glass, which is oxide glass comprising various cationic components in prescribed amounts without Pb, with a refractive index nd of 1.750 to 1.850, an Abbé number ?d of 29.0 to 40.0, and a glass transition temperature of less than 630° C.

Abstract: Zirconium-containing BaO- and PbO-free X-ray opaque glasses having a refractive index nd of about 1.57 to about 1.61 and a high X-ray opacity with an aluminum equivalent thickness of at least about 400% are provided. Such glasses are based on a SiO2—Al2O3—La2O3—ZrO2—Cs2O system with additions of Li2O, Na2O, ZnO and/or Ta2O5. Such glasses may be used, in particular, as dental glasses or as optical glasses.

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 optical glass composition contains, in % by mole, 0% or more and 25.0% or less of SiO2, 20.0% or more and 40.0% or less of B2O3, 0% or more and 5.0% or less of Li2O, 3.0% or more and 15.0% or less of ZnO, 0% or more and 10.0% or less of ZrO2, 2.0% or more and 7.0% or less of Ta2O5, 6.0% or more and 25.0% or less of La2O3, 5.0% or more and 22.0% or less of Gd2O3, 66.5% or less of La2O3+Gd2O3+B2O3 and 26.0% or more of La2O3+Gd2O3, and has nd of 1.83 or higher and 1.86 or lower, vd of 43 or higher and 46 or lower and a liquidus temperature of 1300° C. or lower, and a preform and an optical element are formed from the optical glass composition.

Abstract: Provided is an optical glass having optical constants, a refractive index (nd) of more than 1.9 and an Abbe number (?d) of not more than 38, having a small partial dispersion ratio and capable of being produced from inexpensive materials. The optical glass has a partial dispersion ratio (?g, F) of at most 0.615, and contains, as indispensable ingredients, B2O3, La2O3, TiO2, Nb2O5 and Ta2O5, wherein the ratio, as % by mass, of TiO2/Nb2O5 is at most 0.26 and GeO2/Nb2O5 is at most 0.38. The optical glass contains, in terms of % by mass, the following ingredients: B2O3 ??5 to 22%, La2O3 ??15 to 50%, TiO2 0.01 to 15%, Nb2O5 ??5 to 40%, and Ta2O5 ?0.1 to 25%, and SiO2 0 to 10% and/or GeO2 0 to 10% and/or Al2O3 0 to 10% and/or Gd2O3 0 to 16% and/or ZrO2 0 to 15% and/or WO3 0 to 22% and/or Sb2O3 0 to 1%.

Abstract: A high-refractive index, low-dispersion optical glass which is small in a change of imaging properties due to a change in temperature of the use environment, specifically one capable of realizing an absolute value of multiplication (?×?) of an average coefficient of linear expansion (?) at from ?30 to +70° C. and a photoelastic constant (?) at a wavelength of 546.1 nm of not more than 130×10?12° C.?1×nm×cm?1×Pa?1, is manufactured without using large qualities of components which are high in an environmental load and scarce mineral resources. The optical glass of the invention has an absolute value of multiplication (?×?) of an average coefficient of linear expansion (?) at from ?30 to +70° C. and a photoelastic constant (?) at a wavelength of 546.1 nm of not more than 130×10?12° C.?1×nm×cm?1×Pa?1; and contains more than 0% of SiO2, B2O3 and La2O3, more than 13% and less than 20% of (ZrO2+Nb2O5) and less than 2.0% of ZnO in terms of % by mass on the oxide basis.

Abstract: The invention provides a novel optical glass which has a refractive index (nd) of 1.78 to 2.2 and an Abbe value (?d) of 16 to less than 40 and is suitable for precision mold press molding by virtue of its having a low glass transition temperature, namely, an optical glass which contains by mole in terms of oxides 25 to 60% B2O3, 2 to 45% (in total) TiO2 and Nb2O5 and 1 to 25% WO3 and has a refractive index (nd) of 1.78 to 2.2 and an Abbe value (?d) of 16 to less than 40. Further, the glass contains 5 to 35% La2O3 and 1 to 40% ZnO and has a glass transition temperature (Tg) of 700° C. or below. The optical glass is excellent in meltability, stability and devitrification resistance and has a high refractive index, high light-dispersive power and excellent precision press moldability.

Abstract: An optical glass that is an oxide glass having a very high refractive index in spite of its low-dispersion property, having excellent glass stability and having less susceptibility to coloring.

Abstract: An optical glass having refractive index (nd) exceeding 1.85, Abbe number (?d) of 36 or over, comprising SiO2, B2O3, La2O3, Gd2O3, Ta2O5 and Li2O as essential components, being free of Pb and As components, and having glass transition temperature (Tg) of 630° C. or below.

Abstract: An optical glass of the present invention has optical constants of a refractive index (nd) within a range from 1.75 to 1.85 and an Abbe number (?d) within a range from 35 to 45, comprises SiO2 and B2O3 as essential components and one or more components selected from the group consisting of ZrO2, Nb2O5, Ta2O5 and WO3, has a glass transition temperature (Tg) of 580° C. or below and has weathering resistance (surface method) of Class 1 or Class 2.

Abstract: The invention provides an optical glass for press molding which can satisfy all of the following requirements: (1) it contains no environmentally undesirable components; (2) it can easily achieve a low glass transition point; (3) it has a high refractive index and high dispersion; (4) it can easily provide a glass having an excellent visible light transmittance; and (5) it has excellent resistance to devitrification during preparation of a preform. The optical glass for press molding has a refractive index nd of 1.925 or more, an Abbe's number ?d of 10 to 30, and a glass composition, in % by mass, of 20 to 80% Bi2O3, 10 to 30% B2O3, and 0 to 5.5% GeO2 and is substantially free of lead component, arsenic component, and F component.

Abstract: A high-refractivity low-dispersion optical glass that can be stably supplied and has excellent glass stability and that has coloring reduced, comprises, by mass %, 5 to 32% of total of SiO2 and B2O3, 45 to 65% of total of La2O3, Gd2O3 and Y2O3, 0.5 to 10% of ZnO, 1 to 20% of total of TiO2 and Nb2O5, 0 to 15% of ZrO2, 0 to 2% of WO3, 0 to 20% of Yb2O3, 0 to 10% of total of Li2O, Na2O and K2O, 0 to 10% of total of MgO, CaO, SrO and BaO, 0 to 12% of Ta2O5, 0 to 5% of GeO2, 0 to 10% of Bi2O3, and 0 to 10% of Al2O3, wherein the mass ratio of the content of SiO2 to the content of B2O3, (SiO2/B2O3), is from 0.3 to 1.0, and the mass ratio of the total content of Gd2O3 and Y2O3 to the total content of La2O3, Gd2O3 and Y2O3, (Gd2O3+Y2O3)/(La2O3+Gd2O3+Y2O3), is from 0.05 to 0.6, the optical glass having a refractive index nd of 1.89 to 2.0 and an Abbe's number ?d of 32 to 38 and having a coloring degree ?70 of 430 nm or less.

Abstract: The lead-free and fluorine-free optical glass has a refractive index of 1.60?nd?1.64 and an Abbe number of from 56?vd?64, a transformation temperature less than or equal to 590° C., can be precise pressed and is stable to cystallization. The glass has the following, composition (in weight-% based on oxide content. P2O5, 26-35; B2O3, 10-15; Al2O3, 5.5-10; BaO, 25-37; SrO, 0-6; CaO, 8-15; ZnO, 3-10; Bi2O3, 0-8; Na2O, 0-2; K2O, 0-2; WO3, 0-10; La2O3, 0-2; Nb2O5, 0-1; TiO2,0-<1; ? alkaline earth metal oxides ?40; ? alkali metal oxides, 0-2 and at least one fining agent, 0-0.5.

Abstract: An optical glass that is an oxide glass having a very high refractive index in spite of its low-dispersion property, having excellent glass stability and having less susceptibility to coloring.