Effect of Li2O excess on the crystallization sequence of LAS glass powders
Gundula Helsch  1, *@  , Raschid Al-Mukadam  1@  , Joachim Deubener  1@  , Alessio Zandona  2@  
1 : Clausthal University of Technology, Institute of Non-Metallic Materials, Germany
2 : Friedrich-Alexander Universität Erlangen-Nürnberg, Department of Materials Science, Germany
* : Corresponding author

The surface crystallization of melt-quenched lithium aluminosilicate (LAS) glasses with SiO2-contents between 77 and 79 mol% was investigated by high-temperature X-ray diffractometry. Glasses possessing a ratio Li/Al > 1 underwent far earlier crystallization (starting from 750 °C) than their stoichiometric counterparts, developing solely quartz solid solution (Qss) and keatite solid solution (Kss) crystals during a heat treatment up to 1200 °C. In turn, samples with Li/Al = 1 devitrified only above 900 °C and exhibited the transient formation of cristobalite, whose lattice constants hint at a slight Li+Al stuffing. The composition, structural parameters and critical inversion temperature Tc of the obtained Qss crystals were analyzed and compared with the available literature sources, reaffirming the established mutually linear dependence between these properties.


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