Structural studies of bioactive sol-gel phosphate based glasses

Phosphate based glasses have attracted great interest because of their application as bioresorbable materials. Because of their solubility in body fluid they can be used as degradable temporary implants for hard and soft tissue replacement and augmentation. In the present work, glasses with a composition of 45% P2O5, 35% CaO, 25Yo Na2O have been synthesised using the sol-gel method. Gels were obtained using OP(OR)(x)(OH)(3-x) (x = 1, 2) as phosphorus precursor and alcoxides of calcium and sodium in ethylene glycol. Gels remained amorphous up to a calcination temperature of 400 degrees C At higher temperature, crystalline gamma-Ca2P2O7 was identified A comparison between the structure of the synthesised sol-gel glass and the structure of an analogue glass generated via the conventional melt quenching method has been performed A broad based characterisation approach combining many techniques (X-ray diffraction, thermal analysis, infrared spectroscopy, P-31 solid state NMR spectroscopy, P L-edge XANES) has been used. The structure of sol-gel, and its melt quenched analogue, is mainly formed by chains of (PO4)(3-) tetrahedral sharing two bridging oxygen (i.e. methaphosphate units).