Thermally processed bovine bone serves as a precursor for producing sodium-substituted nanocrystalline carbonate hydroxyapatite

Thermally treated bovine bone via calcination at 900°C with varying holding times of 4, 6, and 8 h was examined for its crystalline structure, functional groups, elemental composition, particle morphology, and thermal stability of the calcined product using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy equipped with energy-dispersive X-ray (SEM-EDX) analysis, and thermal analysis. Calcination of as-received powdered samples at 900°C for 4–6 h effectively removed organic components, yielding B-type sodium-carbonate hydroxyapatite (Na-CHA) as the major calcium phosphate (>99 wt%), with minor calcite (0.20 wt%), whilst following 8 h of calcination time promoted coexistence of Na-CHA (67.62 wt%) with AB-type and hydroxyapatite (HA) (30.20 wt%) with minor phases of dolomite (0.91 wt%), calcite (0.43 wt%), and α-tricalcium phosphate (α-TCP) (0.84 wt%). The average crystallite size of Na-CHA derived from bovine bone is from 82.51 to 83 nm. Additionally, SEM/EDX examination showed that trace elements, such as Mg²⁺ and Na⁺, substituted in the Na-CHA structure with a Ca/P ratio of 1.97–2.04, suggesting that carbonate ions replaced some phosphate groups. Thermal analysis (DTA/DTG/TG) of the calcined product of 8 h revealed three primary mass-loss and decomposition stages: dehydration up to 200°C, followed by the structural release of carbonate groups in the range of 400°C to 700°C, ending with phase transformations to α-TCP and CHA. The high purity of nanocrystalline Na-CHA containing trace elements of Mg²⁺ could benefit numerous applications, particularly in biomaterials, tissue engineering, and sustainable materials.