Solution combustion synthesis of strontium-doped hydroxyapatite: Effect of sintering and low compaction pressure on the mechanical properties and physiological stability

The solution combustion route was used to fabricate strontium (Sr) doped hydroxyapatite (HAp). A low compaction pressure method was adopted for pelletizing the powders (Sr-HAp) prior to physical and mechanical properties measurement. Physiological stability of the pellets was conducted by immersing in Phosphate Buffer Saline (PBS) solution for 24 h. The Sr-HAp produced a comparatively higher hardness and fracture toughness of 0.38 GPa and 0.82 MPa·m^1/2 compared with 0.20 GPa and 0.67 MPa·m^1/2 for undoped HAp. The SEM images suggested that strontium co-existed with the calcium ion in hydroxyapatite due to the presence of irregular bead-like structures on a micro-scale. The Sr-HAp pellets were stable in Phosphate Buffer Saline solution.