Synthesis of lithium aluminosilicate glass and glass-ceramics from spodumene material

The synthesis of lithium alummosilicate glasses and glass-ceramics from spodumene material was investigated. Basing on the general formula Li2-2(x+y)MgxZnyAl2-mBmSizO2z+4, 40 mol% of the Li2O was replaced with 20 mol% of MgO and 20 mol% of ZnO, and 40 mot% of Al2O3 with Ba2O3. BaO was also introduced for improving glass melting behaviour. 2 and 5 wt.% TiO2 was used as nucleation agent. In the TiO2-containing glasses, virgilite was primarily crystallized. The degree of crystallinity was considerably improved at 900 degreesC. Virgilite was transformed into crystals of spodumene solid solutions embedded in a glass matrix, while Zn-gahnite formed a second crystalline phase. Rutile was crystallized in the glasses containing 5 wt.% TiO2. The thermal expansion coefficient for the 2% and the 5 wt.% TiO2-containing glass-ceramics was 6.39 x 10(-7) and 17.1 X 10(-7) K-1, respectively (70-300degreesC). (C) 2004 Elsevier Ltd and Techna Group S.r.l. All rights reserved.