Synthesis of Niobium Doped Zinc Borosilicate Glass-ceramics

The niobium doped oxide glass system, Nb2O5-ZnO-B2O3-SiO2, has relevantdielectric and photoluminescence properties. Glasses with the composition ZnOB2O3-SiO2 (ZBS), with small additions of Nb2O5 (N), N=0, 2.5, 5, 7.5 and 10mol%, were prepared using melt-quenching method. Two series of glasscompositions (S1 and S2) were considered. Series S1, where the contents of ZnO,B2O3 and SiO2 were fixed at 60, 30 and 10 (mol %), respectively, and a secondseries S2, where ZnO, B2O3 and SiO2 were fixed at 60, 20 and 20 (mol %). Thermalproperties such as glass transition and glass crystallization temperatures weredetermined by DSC. Increased amounts of Nb2O5 decreased the glass transitiontemperature in both series of glasses. However, the effect of Nb2O5 addition on theonset crystallization temperature depended on the composition of the base glass.Controlled heat-treatments were performed in order to study the phase formation inthe glasses and the crystalline phases were identified by X-ray diffraction. Themorphology of the precipitated phases was evaluated through SEM imaging.