PREPARATION AND CHARACTERIZATION OF PHOSPHATE GLASSES CONTAINING TITANIUM

A b s t r a c t Clear bubble-free phosphate glasses, having composition 40Na 2 O-10Al 2 O 3 -xTiO 2 -(50-x)P 2 O 5 , (x = 0-20 mol %), were prepared by conventional melt quench method. Density, molar volume, glass transition temperature (Tg), MicroHardness (MH), and Thermal Expansion Coefficient (TEC) were measured as a function of TiO 2 content. Structural investigation was done using Raman and FTIR spectroscopy. Substitution of TiO 2 for P 2 O 5 up to 10 mol %, in the ternary 40Na 2 O-10Al 2 O 3 -50P 2 O 5 glass increases the density, Tg and MH. Above the 10 mol % TiO 2 content, all these properties show a reverse trend. Spectroscopic investigations reveal the depolymerization of the phosphate glass network by systematic conversion of Q 2 structural units into Q 1 and finally into Q 0 structural units. Even though Q 2 to Q 1 conversion is taking place due to breaking of P-O-P linkages, formation of P-O-Ti and P-O-Al linkages provide cross linking between short P-structural units, which make the glass network more rigid. Above 10 mol % TiO 2 content, network is highly depolymerized due to the formation of Q 0 structural