Lead-free and preferably arsenic-free lanthanum heavy flint glass

Lead-free optical glass with a refractive index nd of 1.85≦nd≦1.95 and an Abbé number νd of 28≦νd≦35, and having a composition, in percent by weight based on oxide content, comprising:

• 7 SiO2 3 to 7.5, B2O3 15 to 19.5, La2O3 37 to 47, MgO 0 to 4, CaO 0 to 4, BaO 0 to 4, ZnO 0 to 7, TiO2 6 to 13, ZrO2 1 to 9, Nb2O5 8 to 14,
• wherein a sum total amount of MgO+CaO+BaO+ZnO is from 2 to 10.

Lead-free optical glass with a refractive index nd of 1.86≦nd≦1.94 and an Abbé number νd of 28≦νd≦34, and having a composition, in percent by weight based on oxide content, comprising:

• 8 SiO2 4 to 7, B2O3 16 to 19.5, La2O3 39 to 45, MgO 0 to 4, CaO 0 to 4, BaO 1 to 4, ZnO 2 to 9, TiO2 7 to 12, ZrO2 2 to 9, Nb2O5 9 to 13,
• wherein a sum total amount of MgO+CaO+BaO+ZnO is from 2 to 9.

Lead-free optical glass with a refractive index nd of 1.88≦nd≦1.93 and an Abbé number νd of 29≦νd≦33, and having a composition, in percent by weight based on oxide content, comprising:

• 9 SiO2 4 to 6, B2O3 17 to 19, La2O3 40 to 44, BaO 1 to 3, ZnO 1 to 6, TiO2 7 to 11, ZrO2 3 to 8, Nb2O5 10 to 13.

Lead-free optical glass with a refractive index nd of 1.84≦nd≦1.96 and an Abbé number νd of 27≦νd≦36, and having a composition, in percent by weight based on oxide content, comprising:

• 10 SiO2 1 to 8, B2O3 13 to 19.5, La2O3 34 to 50, MgO 0 to 6, CaO 0 to 6, BaO 0 to 6, ZnO 0 to 9, TiO2 4 to 15, ZrO2 0 to 11, Nb2O5 6 to 14.5,
• wherein a sum total amount of MgO+CaO+BaO+ZnO is from 1 to 10.