IR AND RAMAN STUDIES AND EFFECT OF GAMMA-RADIATION ON CRYSTALLIZATION OF SOME LEAD BORATE GLASSES CONTAINING AL2O3

IR and Raman spectra of glass-ceramics based on PbO-Cr2O3-B2O3 glass composition system have been studied. The bands characteristic of BO3, and BO4functional groups are present in all the samples. An incorporation of Al2O3 (up to ca. 5 mol%) in the initial glass composition considerably changes the glass network structure and relative concentrations of BO3 and BO4 groups. The composition 50 PbO-20 Cr2O3-25 B2O3-5 Al2O3 (in mol%) reveals a maximum fraction of boron in the BO4group. A sample of this compositoin heat treated at 850°C for 25h shows a maximum crystallization fraction with Pb2O&middotCrO4 as a prominent crystalline phase. The glasses irradiated with γ rays inhibit the crystallization into the Pb2O&middotCrO4 phase. They also show relatively smaller thermal conductivity.