Phototropic glass with a refractive index greater than or equal to 1.59, an abbe number greater than or equal to 44 and a density less than or equal to 3.0 g/cm.sup.3

US4686196A · kind A · utility

Assignee

• Schott Glaswerke · DE

Inventors

• Georg Gliemeroth · Eltville am Rhein, DE
• Ludwig Ross · Klein-Winternheim, DE
• Uwe Eichhorn · Großerkmannsdorf, DE
• Eva Hoelzel · Ingelheim am Rhein, DE
• Burkhard Speit · Mainz, DE

Key dates

• Filing date: Feb 13, 1986
• Grant date: Aug 11, 1987
• Expiry date: Feb 13, 2006

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S501/903
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

A phototropic glass with the optical characteristics of n.sub.d greater than to or equal to 1.59 and v.sub.d greater than or equal to 44, and with a density less than or equal to 3.0 g/cm.sup.-3 is provided having a composition comprising: ______________________________________ SiO.sub.2 42-56 B.sub.2 O.sub.3 11-18 Al.sub.2 O.sub.3 0-5 sum of SiO.sub.2, B.sub.2 O.sub.3, and Al.sub.2 O.sub.3 55-75 Li.sub.2 O 3-9 Na.sub.2 O 0-7.98 K.sub.2 O 0-8.22 sum of alkaki metal oxides 7-15 MgO 3-12 CaO 0-3 SrO 0-3 BaO 0-6 ZnO 0-2 sum of alkali earth metal 3-12 oxides amd ZnO TiO.sub.2 3.06-6.74 ZrO.sub.2 2-11 Nb.sub.2 O.sub.5 2.28-8 La.sub.2 O.sub.3 0-3 Er.sub.2 O.sub.3 0-1 ______________________________________