Synthesis and characterization of fluorine-containing hydroxyapatite by a pH-cycling method

Area of Science:

• Materials Science
• Biomaterials Engineering
• Inorganic Chemistry

Background:

• Hydroxyapatite (HA) is a key biomaterial, but its properties can be enhanced through modifications.
• Fluorine incorporation into HA can improve its stability and bioactivity.
• Developing efficient synthesis methods for fluorine-containing hydroxyapatite (FHA) is crucial for advanced applications.

Purpose of the Study:

• To synthesize fluorine-containing hydroxyapatite (FHA) powders using a pH-cycling method.
• To investigate the effect of sodium fluoride (NaF) concentration and pH cycles on fluorine incorporation.
• To characterize the structural and compositional changes in FHA before and after calcination.

Main Methods:

• Synthesis of FHA powders via a pH-cycling method with varying NaF concentrations.
• Calcination of synthesized powders at 1200°C for 1 hour.
• Characterization using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and F-electrode measurements.

Main Results:

• Fluorine incorporation efficiency increased with initial NaF concentration and the number of pH cycles.
• An approximate 60% fluorine incorporation efficiency was achieved, remaining stable after calcination.
• Uncalcined FHA particles were inhomogeneous (mixture of HA and F-rich apatite), while calcined FHA became single-phased.

Conclusions:

• The pH-cycling method is effective for synthesizing FHA, with controllable fluorine content.
• Calcination at 1200°C homogenizes FHA particles into a single-phase material.
• The synthesized FHA shows potential for applications requiring enhanced hydroxyapatite properties.