Glass, glass material for press molding, optical element blank, and optical element
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.
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