Synthesis, Structural, and Mechanical Behavior of β -Ca 3 (PO 4 ) 2 -ZrO 2 Composites Induced by Elevated Thermal Treatments.

Biocompatible β -Ca 3 (PO 4 ) 2 and mechanically stable t- ZrO 2 composites are currently being combined to overcome the demerits of the individual components. A series of five composites were synthesized using an aqueous precipitation technique. Their structural and mechanical stability was examined through X-ray diffraction, Rietveld refinement, FTIR, Raman spectroscopy, high-resolution scanning electron microscopy, and nanoindentation. The characterization results confirmed the formation of β -Ca 3 (PO 4 ) 2 - t -ZrO 2 composites at 1100 °C. Heat treatment above 900 °C resulted in the degradation of the composites because of cationic interdiffusion between Ca 2+ ions and O -2 vacancy in Zr 4+ ions. Sequential thermal treatments correspond to four different fractional phases: calcium-deficient apatite, β -Ca 3 (PO 4 ) 2 , t -ZrO 2 , and m -ZrO 2 . The morphological features confirm in situ synthesis, which reveals abnormal grain growth with voids caused by the upsurge in ZrO 2 content. The mechanical stability data indicate significant variation in Young's modulus and hardness throughout the composite.