Vitrification, crystallization behavior and structure of zinc aluminosilicate glasses
Laurent Cormier, Ludovic Delbes, Benoı̂t Baptiste, Valérie Montouillout
Abstract
The glass formation, crystallization behavior and structure were investigated in the ZnO-Al 2 O 3 -SiO 2 system. The boundaries of the glass forming region are defined, indicating the absence of glasses along the ZnO-SiO 2 binary and the role of Al to improve glass formation. The crystallization behavior has been clarified for representative glass compositions showing first crystallization of willemite near the ZnO-SiO 2 binary and a metastable zinc aluminosilicate solid solution for higher Al 2 O 3 /SiO 2 content. Gahnite appears as a second phase and is mainly present near the center of the tectosilicate join. Glass structure was studied using 27 Al NMR spectroscopy, neutron and X-ray diffraction and molecular dynamics simulation. Both Al and Zn are shown to be distributed between four-fold and five-fold sites. The proportion of [4] Al is more important near the ZnAl 2 O 4 -SiO 2 join. A remarkable similar behavior is revealed for the glass forming ability and structural properties between MgO and ZnO aluminosilicate systems.