Covers glasses in the range (wt%): 10-20 B2O3, 11-35 La2O3, 15-50 ThO2, 5-25 Ta2O5. 0-5 TiO2. 0-5 CdO, 0-15 Al2O3 with (Nb2O5 + WO3 + PbO) = 6.7 (at least 2 Nb2O5 with TiO2 + CdO = about 0-5) whilst La2O3 could be replaced by up to 5 alkaline earth metal oxide. A second claim was for 10-15 B2O3, 11-29 La2O3, 24-50 ThO2, 15-25 Ta2O5, 9-13 Nb2O5 with RI>1.962.
Origin
Unknown
Journal Title
Usp 3 150 990, 29/9/64
Sector
Refractive Indexes
Class
RI 17