Crystal glass free of lead and barium exhibiting high transmission of light

摘要

Pb- and Ba-free crystal glass (I) has a light transmission of at least 85%, a refraction index (nd) of more than 1.52, a density of at least 2.45g/cm3, and a K2O+ZnO amt. of more than 10 wt.%. (I) contains 50-75 (wt.%) SiO2, 2-15 Na2O, 2-15 K2O, 3-12 CaO, 0-10 B2O3, 0-5 Al2O3, 0-5 LisO, 0-5 MgO, 0-7 SrO, 0-7 ZnO, 0-8 TiO2, 0-5 ZrO2, 0.1-5 Nb2O5, 0-5 Ta2O5 and 0-2F. The sum of TiO2 + ZrO2 + Nb2O5 + Ta2O5 is 0.3-12 wt.% and of the alkalis is more than 15 wt.%. (I) may also contain 50-75 (wt.%) SiO2, 6-12 Na2O, 10-15 K2O, 3-12 CaO, 0-10 B2O3, 0.4-3 Al2O3, 0-5 Li2O, 0-5 MgO, 0-7 SrO, 0-7 ZnO, 0.3-8 TiO2, 0-5 ZrO2, 0-5 Nb2O5, 0-5 Ta2O5 and 0-2F. The sum of TiO2 + ZrO2 + Nb2O5 + Ta2O5 is 0.3-12 wt.% or 0.4-12 wt.%. (I) pref. contains 10-15 (wt.%) K2O, 6-12 Na2O and 7-12 CaO.