STRUCTURAL BEHAVIOUR OF NIOBIUM PHOSPHATE VITROCERAMICS IN SIMULATED BODY FLUID

The changes induced on the local structure of calcium-posphate vitroceramics with LiNbO3 crystallites by increasing of Nb2O5·Li2O content in the precursor glass sample as well as by soaking in simulated body fluid (SBF) were investigated by 31P nuclear magnetic resonance. The 31P magic-angle-spinning nuclear magnetic resonance (MAS NMR) spectra of these samples consist in two groups of lines occurring between –7 and –10 ppm respectively –23 and –34 ppm. The preponderance of the 31P resonant lines recorded between –7 and –10 ppm increases with Nb2O5·Li2O content. On the other hand, the MAS NMR data evidence that the atomic environment of phosphorus atoms in the second configuration sphere, particularly when calcium is the main neighbour, is modified after immersion in SBF