NEW FAMILIES OF GLASSES BASED ON BI2O3

New families of glasses based on Bi2O3 were found in the systems Bi2O3-Li2O, Bi2O3-ZnO-Li2O (Na2O, K2O) and Bi2O3-ZnO-CaO (SrO, BaO) and their glass forming regions were determined by melting 6 g batches. Glass formation in the Bi2O3-ZnO-BaO-Li2O quaternary system was also explored. Large amounts of glass with the optimised composition 45Bi(2)O(3)-15BaO-10CaO-10ZnO-20Li(2)O could be prepared from a 200 g batch. The thermal and optical properties of these glasses were investigated. Their glass transition temperature ranges from 280 to 350 degrees C, they have expansion coefficients of about 150x10(-7)degrees C-1, high densities of up to 8 . 3 gl cm(3) and high refractive index up to 2.5. They are transparent in visible region and transmit 70% of light in the infrared range 3.5-6.8 mu m with cutoff wavelength at about 9 mu m (0.8 mm).