Addition of Alumina to Nanoporous Calcium Titanium Phosphate Glass-Ceramics and its Effects on Crystallization Behavior

Microporous Calcium Titanium Phosphate glass-ceramics have many uses in high-tech industries. For example, they have applications in catalysts industry. In this study, different molar percentages of alumina were added to a glass with P2O5 30, CaO 45, TiO2 25 (mol%) composition. The samples were melted at 1350°C and crystallization heat treatment was performed on the glasses after cooling to make glass-ceramics. The Differential Thermal Analysis (DTA) was used to determine nucleation and crystallization temperature. The DTA curve of the sample had 4 molar% and alumina had the sharpest crystallization peak. The CP and CTP phases were the most crystalline phases in all samples. The soluble CP phase disappeared and the porous structure of the CPT crystals remained through the acid washing of the samples. The results showed that the addition of alumina decreased the crystallization temperature, time and temperature of crystallization, and also increased the average size of porosities (from 12 to 16 nm).