Niobium pentoxide-containing borosilicate glasses

Claim 1

A NIOBIUM PENTOXIDE-CONTAINING BOROSILICATE GLASS COMPOSITION HAVING AN INDEX OF REFRACTION (NE) BETWEEN 1.5410 AND 1.7942, AN ABBE VALUE (VE) OF BETWEEN 23.5 AND 49.9 AND BEING CHARACTERIZED BY A HIGH DEGREE OF CHEMICAL RESISTANCE, CONSISTING ESSENTIALLY OF A. FROM ABOUT 30% TO ABOUT 42% BY WEIGHT OF LTHE COMBINED GLASS-FORMING OXIDES SIO2 AND B2O3, WHEREIN THE SIO2 CONTENT OF SAID COMBINED AMOUNT COMPRISES BETWEEN 22% AND ABOUT 30% BY WEIGHT AND THE B2O3 CONTENT OF SAID COMBINED AMOUNT COMPRISES BETWEEN ABOUT 8% AND ABOUT 14% BY WEIGHT; B. BETWEEN ABOUT 9% AND ABOUT 22% BY WEIGHT OF K2O, C. AND A COMPONENT SELECTED FROM THE GROUP CONSISTING OF I.) BETWEEN ABOUT 37% AND ABOUT 53% BY WEIGHT OF NB2O5 AND II.) FROM ABOUT 37% TO ABOUT 58% BY WEIGHT OF A COMBINATION OF NB2O5 AND A FURTHER COMPONENT, WHEREIN THE NB2O5 CONTENT IN SAID COMBINED AMOUNT COMPRISES BETWEEN ABOUT 2% AND ABOUT 48% BY WEIGHT AND SAID ADDITIONAL COMPONENT IN COMBINATION WITH THE NB2O5 IS SELECTED FROM THE GROUP CONSISTING OF A. AN AMOUNT OF AN OXIDE OF THE ELEMENT LI, MG, AL OR BI, SAID AMOUNT NOT SUBSTANTIALLY EXCEEDING ABOUT 10% BY WEIGHT. B. AN AMOUNT OF AN OXIDE OF THE ELEMENT NA OR TE, SAID AMOUNT NOT SUBSTANTIALLY EXCEEDING ABOUT 20% BY WEIGHT; C. AN AMOUNT OF AN OXIDE OF THE ELEMENT CA, SR, BA, ZN, CD, PB, IN, LA OR SB, SAID AMOUNT NOT SUBSTANTIALLY EXCEEDING ABOUT 30% BY WEIGHT; D. AN AMOUNT OF TIO2, SAID AMOUNT NOT SUBSTANTIALLY EXCEEDING ABOUT 35% BY WEIGHT; E. AN AMOUNT OF TA2O5, SAID AMOUNT NOT SUBSTANTIALLY EXCEEDING ABOUT 38% BY WEIGHT; F. AN AMOUNT OF A FLOURIDE OF THE ELEMENT LI, NA, CA OR AL, SAID AMOUNT NOT SUBSTANTIALLY EXCEEDING ABOUT 10% BY WEIGHT; G. AN AMOUNT OF A FLUORIDE OF THE ELEMENT MG OR SR, SAID AMOUNT NOT SUBSTANTIALLY EXCEEDING ABOUT 20% BY WEIGHT; H. AN AMOUNT OF A FLUORIDE OF LTHE ELEMENT BA OR PB, SAID AMOUNT NOT SUBSTANTIALLY EXCEEDING ABOUT 30% BY WEIGHT; I. AN AMOUNT OF KHF2, SAID AMOUNT NOT SUBSTANTIALLY EXCEEDING ABOUT 30% BY WEIGHT; AND J. AN AMOUNT OF K2TIF6, SAID AMOUNT NOT SUBSTANTIALLY EXCEEDING ABOUT 30% BY WEIGHT.