Abstract: To provide: an optical glass having a high refractive index and a relatively low specific gravity; and a corresponding optical element. An optical glass which has a refractive index nd of 1.80 to 2.00 and an Abbe number vd of 17 to 22, contains 25 to 40 mass % of P2O5, 15 to 40 mass % of Nb2O5, 10 to 35 mass % of TiO2, 3 to 12 mass % of B2O3, 0 to 15 mass % of BaO, greater than 0 mass % and 10 mass % or less of Li2O, greater than 0 mass % and 15 mass % or less of a total of Li2O, Na2O, K2O, and Cs2O [Li2O+Na2O+K2O+Cs2O], has a mass ratio [TiO2/(Nb2O5+TiO2+WO3+Bi2O3+Ta2O5)] of TiO2 to the total of Nb2O5, TiO2, WO3, Bi2O3, and Ta2O5 of 0.33 to 0.60, and does not substantially contain F.

Abstract: An aspect of the present invention relates to optical glass, wherein, in a glass composition based on oxides, a content of P2O5 is in the range of 20˜34 weight %; a content of B2O3 is over 0 weight % but 10 weight % or less; a weight ratio (B2O3/P2O5) is over 0 but less than 0.39; a weight ratio [TiO2/(TiO2+Nb2O5+WO3+Bi2O3+Ta2O5)] is in the range of 0.059˜0.180; and a weight ratio [(P2O5+B2O3+SiO2)/(Na2O+K2O+Li2O)] is in the range of 1.39˜1.80, the optical glass having a refractive index nd of 1.78˜1.83, and an Abbe's number vd of 20˜25.

Abstract: The formation of cracks is suppressed in a drying process for a water-containing wet gel without modifying the gel and without using a reagent. A water-containing wet gel is dried by removing water and then removing the remaining solvent. For example, a wet-gel container storing water-containing wet gel, containing a wet gel and a solvent, is heated. The solvent is vaporized into an upper space of the wet-gel container. The solvent-containing gas diffuses into a dehydrating agent container, and water is removed by a dehydrating agent. This state is maintained for one to two days to remove almost all amount of water from the solvent. Thereafter, the dehydrating agent container is detached and the wet gel, from which water has been removed, is heated to almost completely remove the solvent, and further heated at a higher temperature to completely remove the solvent to obtain a crack-free dry gel.

Abstract: An aspect of the present invention relates to optical glass, wherein, in a glass composition based on oxides, a content of P2O5 is in the range of 20˜34 weight %; a content of B2O3 is over 0 weight % but 10 weight % or less; a weight ratio (B2O3/P2O5) is over 0 but less than 0.39; a weight ratio [TiO2/(TiO2+Nb2O5+WO3+Bi2O3+Ta2O5)] is in the range of 0.059˜0.180; and a weight ratio [(P2O5+B2O3+SiO2)/(Na2O+K2O+Li2O)] is in the range of 1.39˜1.80, the optical glass having a refractive index nd of 1.78˜1.83, and an Abbe's number vd of 20˜25.

Abstract: The formation of cracks is suppressed in a drying process for a water-containing wet gel without modifying the gel and without using a reagent. A water-containing wet gel is dried by removing water and then removing the remaining solvent. For example, a wet-gel container storing water-containing wet gel, containing a wet gel and a solvent, is heated. The solvent is vaporized into an upper space of the wet-gel container. The solvent-containing gas diffuses into a dehydrating agent container, and water is removed by a dehydrating agent. This state is maintained for one to two days to remove almost all amount of water from the solvent. Thereafter, the dehydrating agent container is detached and the wet gel, from which water has been removed, is heated to almost completely remove the solvent, and further heated at a higher temperature to completely remove the solvent to obtain a crack-free dry gel.