Nucleation behavior of Li2O-Na2O-SiO2 glass doped with platinum

Nucleation behavior of 0.5L(2)O.0.5Na(2)O.2SiO(2) glass doped with 0.005 mass% platinum as a nucleating agent was studied. Differential thermal analysis (DTA) showed that no exothermic peak due to crystallization appeared in the as-quenched bulk glass with Pt addition, but that a crystallization peak appeared in the glass with Pt addition, which was heat-treated at lower temperature previously. A number of crystal particles were observed in the interior of the glass with Pt addition after two stage heat-treatments. The crystal particles had a needle-like shape. General needle-like crystals and abnormal ones were observed, the latter of which is dendrite of fiber-like shape. The crystalline phase, precipitated in the glass, was identified as Li2O.SiO2 by X-ray diffraction (XRD) measurement. The growth rate of the Li2O.SiO2 Crystals was determined with an optical microscope, and was found to increase steadily with rising temperature in the range 580-680degreesC.