| 摘要 |
A lead- and barium-free crystal glass having a refractive index of at least 1.55, with in % by weight, more than 50% and less than 60% SiO<SUB>2</SUB>, more than 0.6% and less than 4% B<SUB>2</SUB>O<SUB>3</SUB>, less than 3% K<SUB>2</SUB>O, more than 12% and less than 15% Na<SUB>2</SUB>O, more than 4% and less than 11% CaO, more than 0.25% and less than 5% Al<SUB>2</SUB>O<SUB>3</SUB>, less than 2% MgO, and between 8 and 16% ZnO, with the proviso that the total content of the oxides of Pb, Ba and As is below 0.1%, the total content of the oxides of Ti and La is below 5% and the total content of the oxides of Nb, Ta, Yb, Y, W, Bi and Zr is below 5%, wherein at most 1% oxides of Nb, Ta and Yb respectively and 3% of the oxides of Y, W, Bi and Zr respectively are included.
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