Effect of zinc substitution for calcium on the structure, dissolution behavior and apatite formation of CaO-ZnO-SiO2-P2O5 bioceramics

A series of 5, 10 and 20 mol% zinc substituted for calcium bioceramics with composition of CaO-ZnO-SiO2-P2O5 were successfully prepared by sintering the sol-gel-derived powders. The effects of zinc on samples structure, dissolution behavior and apatite-forming ability were comprehensively investigated by means of X-ray diffraction (XRD), scanning electron microscopy/energy-dispersive X-ray technique (SEM/EDX) and in vitro tests. The results indicated that with more zinc substitution, calcium silicate phases of Ca3(Si3O9) and β-Ca(SiO3) gradually disappeared, whereas new phases of Ca2ZnSi2O7, SiO2 and ZnSiO4 were induced. Moreover, the samples dissolution rate decreased and the apatite-forming ability was delayed, suggesting that a controlled rate of dissolution and apatite formation of CaSiO3-Ca2ZnSi2O7-based bioceramics can be achieved.