Raman spectra and density of Li2O–B2O3–GeO2 glasses with high Li2O content

One series of glass having the molar formula y[42.5Li2O·57.5GeO2]·(1−y)[42.5Li2O·57.5B2O3] where y ranged between 0 and 0.55 has been prepared and measured for density, molar volume and Raman spectra. No density anomaly was observed throughout the composition range of the studied glasses. The large difference in molecular mass between that of B2O3 and GeO2 is the reason for the density change. The linear change in density reveals that each oxide in the glass would contribute to the density by a specific factor. Alkali oxide is incorporated into the borate as well as the germanate networks. There are three essential Raman broad bands at ∼525, ∼775 and ∼835 cm−1. With increasing GeO2 content, the number of NBOs associated with Q2 decreases in the germanate network while three-membered rings of GeO4 tetrahedra are formed. The number of borate groups containing four coordinated boron decreases with increasing GeO2 content at the expense of B2O3.