FTIR, Raman and NMR investigation of CaO-SiO2-P2O5 and CaO-SiO2-TiO2-P2O5 glasses

The role of P2O5 on the structure of CaO-SiO2-P2O5 and CaO-SiO2-TiO2-P2O5 glasses was identified using Fourier transformation infrared (FTIR), Raman and Magic Angular Spinning Nuclear Magnetic Resonance (MAS NMR) spectra in this study to provide some fundamental clues for titanium and phosphorus extraction. In both systems, the vibration signals of Q(0)(Si), Q(1)(Si), Q(2)(%), and Q(3)(Si) were detected and the dominant structural units associated with P-0 groups were isolated Q (P) and terminal Q1(P) (Q(Si,P), i represents the number of bridging oxygen per Si or P). The added P2O5 resulted in an increase of Q3(Si) at the cost of Q(0)(Si), Q(1)(Si), and Q(2)(Si) and the degree of polymerization (DOP) of the glasses was therefore increased; additionally, the mole ratio of Q(0)(P) to Q(1)(P) decreased with increasing P2O5 content, indicating an equilibrium reaction between Q(0)(P) and Q(1)(P). Furthermore, the presence of TiO2 resulted in a more complicated structure in the CaO-SiO2-TiO2-P2O5 glasses and the structural units related to Q(0)(P), O-Ti-O deformation and TiO44- monomers were clearly clarified. (C) 2015 Elsevier B.V. All rights reserved.