New sol-gel synthesis of a (CaO)(0.3)( Na2O)(0.2)(P2O5)(0.5) bioresorbable glass and its structural characterisation

An improved sol-gel synthesis of (CaO)(0.3)(Na2O)(0.2)(P2O5)(0.5) bioresorbable glass has been developed. The structures of both the dried gel and the stabilised sol-gel glass have been characterised using high-energy XRD, P-31 MAS NMR and FT-IR spectroscopy. The structure of the analogous melt-quench prepared glass has also been studied for comparison. The results show that the dried gel has a structure consisting of mainly Q(0) and Q(1) phosphate units, whereas that of the stabilised sol-gel glass comprises predominantly Q(1) and Q(2) units. Furthermore, it is demonstrated that the structure of the sol-gel glass is similar to that of its melt-quenched counterpart except for the presence of hydroxyl groups which terminate the phosphate chains, reducing the connectivity of the network.