Non-isothermal Kinetic Analysis of Synthesis of Medical Applicable Fluorapatite in Solid-state Reaction

This paper presents the synthesis of Fluorapatite particles (FA; Ca₁₀ (PO₄)₆F₂) as biomaterials for bone regeneration and dentistry. The particles were synthesized by mechanically activating CaHPO₄, Ca(OH)₂ and CaF₂, which served as the precursor materials. Subsequently, the precursors were heated under a non-isothermal condition using simultaneous thermo-gravimetry (TG) and differential thermal analysis (DTA). The heating rates employed were 7, 10, and 15 °C min⁻¹, and the process was conducted up to 1100 °C in an Ar atmosphere. The X-ray diffraction (XRD) was utilized to analyze the phase composition. To determine the activation energy variation with the degree of conversion (α), four isoconversional methods: starink, KAS, FWO, and Friedman were employed for the kinetic study of synthesizing Fluorapatite particles under non-isothermal conditions. The results indicate that the activation energy does not change with α. The empirical kinetic triplets (E, A, and g(a)) were calculated using a fitting model and the invariant kinetic parameters (IKP) method. By combining the isoconversional methods, IKP, and the fitting model, the obtained kinetic model was identified as Diffusion-controlled of third order (D3) with \(g\left(\alpha \right)={[1-{\left(1-a\right)}^\frac{1}{3}]}^{2}\) $g\left(\alpha \right)={[1-{\left(1,-,a\right)}^{\frac{1}{3}}]}^2$ .