EFFECT OF TIO2 ADDITION ON THE PROPERTIES OF COMPLEX ALUMINOSILICATE GLASSES AND GLASS-CERAMICS

The nucleating effect of titania during glass crystallization has been studied in a complex glassy system where some particular oxides, such as ZnO and MgO, which present chemical and thermodynamic affinity for titanium have been added. Such additions tend to produce phase separa tion in the glass and leads to titanate phases formation in the glass- ceramic. Moreover, the presence of lithia has a promoting effect on bo th mechanisms because the lowered viscosity increases cation diffusion . Various thermal, microscopic, and diffractometric techniques have be en used to investigate the amorphous and the crystalline phase. (C) 19 97 Elsevier Science Ltd.