First stages of crystallization in a silicate glass: study by high-resolution electron microscopy.
The first stages of crystallization have been investigated for a glass in the system SiO2-Al2O3-Li2O with small amounts of titanium and zirconium as nucleating elements. The studies were performed by electron diffraction and electron microscopy in high-resolution mode. It has been found that the two phases forming the final glass ceramic crystallize successively. The first one gives small crystallites (less than 5 nm) randomly dispersed. The lattice plane images in several orientations are in good agreement with TiZrO4 crystal lattice. At 780 degrees C the average crystal size increases with increasing time of the heat treatments from 2.5 nm at 0.5 h to 4.5 nm at 2 h and then remains nearly constant. The crystallization of the second phase, a silicate solid solution with beta-quartz structure, occurs after complete crystallization of TiZrO4.
Ramos
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A
Laboratoire de Minéralogie-Cristallographie, associé au CNRS, Universités P. et M. Curie, Paris, France.
Gandais
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M
D002516:Ceramics / Q000032:analysis; D003460:Crystallization; D005898:Glass / Q000032:analysis; D008854:Microscopy, Electron / Q000379:methods*; D012822:Silicon Dioxide / Q000032:analysis*
D012822:Silicon Dioxide