Light flint glass composition used in optical applications

摘要

Lead-free optical light flint and double-light flint glasses having a refractive index n d of between 1.52 and 1.57 and an Abbe coefficient * small Greek nu *d of between 43 and 52 are described, which have the following composition (in % by weight based on oxides): SiO 2 48-55, B 2 O 3 7-9, K 2 O 18-20, Al 2 O 3 7-9, La 2 O 3 0.1-2, ZrO 2 0-1, * capital Greek sigma * La 2 O 3 +ZrO 2 0.5-2, TiO 2 5.5-12, F - 1.5-6, (Al 2 O 3 +La 2 O 3 )/(TiO 2 +ZrO 2 ) = 0.73-1.15. The glasses show outstanding crystallization stability and very good chemical resistance. Fining agents Sb 2 O 3 and/or Cl - may be present in amount up to 0.5wt%.