Thermochimica Acta, Vol.259, No.2, 269-275, 1995
Bulk and Surface Crystallization of Lead Tetragermanate Glass - A DTA Study
The surface and bulk crystallisation of lead tetragermanate glass has been studied by differential thermal analysis. The influence of the specific surface area of the sample and the nucleation heat-treatment on the crystallisation is pointed out. Infrared spectroscopy measurements suggest that the addition of PbO to germanium oxide leads to a change in the coordination number of germanium atoms from 4 to 6. The phases which crystallise during the DTA runs were identified by X-ray diffraction as hexagonal and monoclinic PbGeO4O9. The activation energy of crystal growth was also evaluated from DTA curves. A value of about 300 kJ mol(-1) was calculated from surface and bulk crystallisation.