Patent ID: 7605100

Claim:
A lead-free and arsenic-free glass with good chemical durability and stability against crystallization, which has a refractive index of 1.57≦n d ≦1.61, an Abbe number of 56≦υ d ≦63, and a transformation temperature Tg≦520° C., said lead-free and arsenic-free glass consisting, in wt % based on oxide content, of: SiO 2 37 — 46 B 2 O 3 12 — 18 Al 2 O 3 1 — 7 Li 2 O 5.5 — <7 Na 2 O 1 — 5 K 2 O < 4 MgO < 5 CaO < 7 BaO 21 — 29 SrO 0.1 — 1.5 ZnO 1 — 4.5 TiO 2 0.1 — 0.5 ZrO 2 < 0.7 Σ TiO 2 + ZrO 2 < 0.9 Sb 2 O 3 0 — 1 SnO 0 — 1 NaCl 0 — 1 SO 4 2− 0 — 1 F − 0 — 1.