Patent ID: 7341965

Claim:
A process for producing a bismuth-containing glass, in which a glass melt is formed under oxidizing conditions and said glass melt has a composition in mol % comprising: Bi 2 O 3 20-60 GeO 2 3-40 La 2 O 3 0-20 SiO 2 1-19.10 Ga 2 O 3 0-10.10 B 2 O 3 15-40 Al 2 O 3 0.5-30 WO 3 0-30 Nb 2 O 5 0-30 Ta 2 O 5 0-15 TiO 2 0-30 ZrO 2 0-30 SnO 2 0-30 Li 2 O at least 1 M I 2 O 0-40 M II O 0-30 F and/or Cl 0-10 Bi 2 O 3 + GeO 2 + B 2 O 3 + Al 2 O 3 5-85, where M 1 is at least one of Li, Na, K, Rb and Cs and M 11 is at least one of Be, Mg, Ca, Sr and Ba; and which is substantially free of tellurium.