Physiochemical stability of chemically-modified nanoapatites sintered at different temperatures

Nanostructured apatite has been widely used as a bone substitute material due to its biological similarity to the natural bone mineral. To enhance further the biomineralisation and introduce bactericidal properly into HA, co-substitution of Ag and Si has been investigated. A co-substituted nanosized apatite (Ag/Si-HA) containing Ag (0.3 wt %) and Si (0.8 wt %) was synthesized by an aqueous precipitation technique. Bone-apatite mimicking morphology of dimensions ~50 nm in length and ~10 nm in width was observed for the Ag/Si-HA nano powder. XRF detected the presence of Ag and Si in phase-pure Ag/Si-HA. The Ag/Si-HA nano powders were then compacted and sintered at various temperatures (900-1300 °C) and found to achieve a maximum densification of 93 % at 1300 °C, with a gram size of approximately 1 μm. Phase-purity was maintained up to a temperature of 1300 °C, as observed from the XRD pattern. This study thus demonstrated that a phase-pure Ag/Si-HA was synthesized via an aqueous precipitation technique.