Crystallization of the glasses within the SiO2-Li2O-TiO2 system

Glasses from the ternary system SiO2-Li2O-TiO2 with increasing titania content replacing silica were prepared by melting-annealing technique. Structural FTIR, thermal and differential thermal analysis (DTA) properties of the glasses were measured and evaluated. X-ray diffraction and scanning electron microscope investigations were done to identify the crystalline phases formed together with revealing their morphological features. The coefficient of thermal expansion (CTE) data of glass-ceramic samples are identified to be between 80.83 x 10(-7) degrees C-1 and 120.04 x 10(-7) degrees C-1 (23-500 degrees C). The increase of the CTE is assumed to be concomitant with the increase of the crystallization of lithium metasilicate (Li2SiO3) phase or quartz (SiO2). Titania is assumed to behave primarily partly as a modifier oxide and at high titania content; it is assumed to act as former (TiO4) groups. X-ray diffraction patterns indicate that the pure lithium silicate glass produces lithium disilicate (LS2) and quartz (SiO2) as crystalline phases and with increasing TiO2, first it acts as a nucleating agent initiating the formation of different crystalline silica phases beside (LS2) then titania is separated at 15 %TiO2 and 30%TiO2 as lithium titanate. The microhardness and densities values are calculated. The studied samples show promising thermal and mechanical properties especially for both CTE and microhardness values, beside their chemical stability which could be applied for commercial uses.

Automated summary

The glasses from the ternary system SiO2-Li2O-TiO2 with increasing titania content replacing silica were prepared by melting-annealing technique. The thermal and structural properties of the glasses were evaluated, showing an increase in coefficient of thermal expansion with titania content. X-ray diffraction and SEM investigations revealed the formation of different crystalline phases with increasing TiO2 content, impacting the mechanical properties of the glass.