TY - JOUR A1 - Aguiar, H. A1 - Solla, E.L. A1 - Serra, J. A1 - González, P. A1 - León, B. A1 - Malz, Frank A1 - Jäger, Christian T1 - Raman and NMR study of bioactive Na2O-MgO-CaO-P2O5-SiO2 glasses JF - Journal of non-crystalline solids N2 - The results of a structural study combining NMR and Raman spectroscopy of several melt-derived glasses in the system Na2O–MgO–CaO–P2O5–SiO2 are presented. The Raman spectra show clear changes in the Si–O–Si vibrational modes (related to the bridging oxygen atoms, BO) and also verify the presence of non-bridging oxygen atoms (NBO), also named terminal oxygens. The intensity of the Si–O–NBO stretching mode depends on the cation concentration. It can be concluded from the NMR studies that the MgO-containing samples have orthophosphate units charge-compensated by Ca2+ and Mg2+. The silicate matrix also contains both types of two-valent cations and consists of Q2 and Q1 units. Similarly, the Na2O-containing samples contain isolated orthophosphate units in a silicate matrix (Q2 and Q3 units), both charge-compensated by mixed cations Ca2+ and Na+. These experimental data were compared with theoretical parameters given by the Stevels model, which is a suitable tool for understanding bioactive behavior of these glasses. Furthermore, results of the in vitro tests carried out in simulated body fluids are presented and compared with both Raman and NMR structural data. KW - Raman KW - NMR KW - Solid state KW - Bioactive glasses KW - Glass ceramics PY - 2008 DO - https://doi.org/10.1016/j.jnoncrysol.2008.07.033 SN - 0022-3093 VL - 354 IS - 45-46 SP - 5004 EP - 5008 PB - North-Holland Publ. Co. CY - Amsterdam AN - OPUS4-18364 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -