GLASS, GLASS MATERIAL FOR PRESS MOLDING, OPTICAL ELEMENT BLANK AND OPTICAL ELEMENT

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PROBLEM TO BE SOLVED : To provide a high refractive low dispersion glass that is a glass including a rare earth oxide and is excellent in thermal stability. SOLUTION : A glass has, in a glass composition in terms of oxides, a mass ratio of the content of SiO2 to the total content of B2O3, SiO2 and P2O5 of 0.050 to 0.250, a mass ratio of the content of Gd2O3 to the total content of La2O3, Gd2O3, Y2O3, Yb2O3 and Lu2O3 of less than 0.360, a mass ratio of the total content of B2O3, SiO2 and P2O5 to the total content of La2O3, Gd2O3, Y2O3, Yb2O3, Lu2O3 and ZrO2 of not less than 0.405 to less than 0.460, a mass ratio of Ta2O5 to the total content of La2O3, Gd2O3, Y2O3, Yb2O3, Lu2O3 and ZrO2 of less than 0.030, a mass ratio of the total content of Nb2O5, TiO2, WO3 and Bi2O3 to the total content of La2O3, Gd2O3, Y2O3, Yb2O3, Lu2O3 and ZrO2 of less than 0.013, a content of Gd2O3 of more than 8.0 mass%, a content of La2O3 of 38 to 48 mass% and a content of Nb2O5 of less than 1.0 mass%, and has a refractive index nd in the range of 1.78 to 1.80 and an Abbe number νd in the range of 47 to 50. SELECTED DRAWING : None COPYRIGHT : (C)2016, JPO&INPIT