Nanocrystalline glass-ceramics formation

The atomic scale mechanism of the transition of the glass structure into the structure of a compound crystallizing in it has been studied. It has been demonstrated that near the glass transformation temperature Tg the crystallization by direct ordering of the amorphous glass structure through local displacements of its elements can take place. TiO2 nucleated crystallization of SiO2-Al2O3-MgO glass-ceramics is the example. Up to now, it has been thought that amorphous phase separation is an indispensable step in the glass-ceramization. Crystallization with the direct ordering mechanism creates the compounds whose chemical composition and structure are close to those of glass network or to the domains and clusters in it. The (Mg, Al)-titanate, and high quartz structure solid solutions appearence are here the example.