Devitrification Behavior of Glasses In the Lead Tetragermanate-Lithium Tetragermanate Composition Range

The effect of replacing PbO by Li2O on the glass structure, on the glass transition temperature and on devitrification behaviour in a series of glasses in the lead tetragermanare-lithium tetragermanate composition range has been studied by differential thermal analysis, X-ray diffraction and Fourier-transform infrared spectra. The anion network of all glasses contains GeO4 and GeO6 groups in the same molar ratio. The glass transition temperature is increased by the progressive replacement of Pb2+ by Li+ ions. All glasses, except the lead tetragermanate glass, exhibit internal crystal nucleation without any addition of nucleating agent. The crystallizing phases have been identified and related to devitrification mechanisms