Structural characterization of TiO2-P2O5-CaO glasses by spectroscopy

The structure of glasses with composition x TiO2 center dot(65 - x) P2O5 center dot 35 CaO (x = 0-30 mol%) has been studied and their glass transition temperature, Raman and NMR spectra have been analysed. For TiO2-free glass two phosphate species have been identified as Q(2) and Q(3). Increasing TiO2 content in glass compositions results in the disappearance of the Q3 and Q2 species and in the formation of, mainly, pyrophosphate structure, Q(1). In calcium titanophosphate glass with higher TiO2 content the structure consists of a distorted Ti octahedral linked to pyrophosphate unit through P-O-Ti bonds. In these glass series the structural cohesion increases with TiO2, although a depolymerization in the original P-O-P network occurs. The study of these glasses and the understanding of their structural characteristics can give a valuable contribution for the clarification of their degradation behaviour namely in biological environments. (C) 2009 Elsevier Ltd. All fights reserved.