Papers by Keyword: Carbonate Substitution

Abstract: In-vitro experiment method was used to study biomineralization properties of carbonate apatite bulk and electrophoresis coating with different carbonate contents. The mineralization processes in SBF solution were investigated by means of XRD, SEM and so on. Research results show that the apatite with poor crystallization and small grain size induced by the carbonate substitution is beneficial to the sintering of the bulk and the formation of the bone-like hydroxyl-carbonate apatite (HCA) layer on the surface after soaking in the SBF. However, the carbonate substitution greatly reduces the pore size and porosity of coating, which is not conducive to the deposition and growth of the mineralized layer, thus weakens the biomineralization properties of the coating.

Abstract: Carbonated apatite, the basic mineral component in human hard tissues and an important bioceramic material, has been extensively studied. However, its atomic arrangements in apatite crystal structure and its experimental characterization are still not lack of debating. We analyzed infrared (IR) vibrational spectroscopy for carbonated apatite determinations, by comparatively studying the IR spectra of hydroxyapatite and of surface carbonate absorption, biological apatites (human enamel, human cortical bone, and two animal bones) and carbonated apatite. The carbonated apatite samples were sythesized by various methods, including precipitation method, hydrothermal reaction and solid-gas reaction at high temperature. The comparative study indicates that the bands at ~880 cm^-1, ~1413 cm^-1, and ~1450 cm^-1 should not be used to identify carbonated apatite since they may result from carbonate absorption on surfaces of apatite crystals or separated carbonate phase present with apatite crystals. The IR characteristic bands of carbonate substitution in apatites should be: ν₃ at ~1465 cm^-1 for type-B (CO₃ substituting for PO₄) and ν₃ band at ~1546 cm^-1 for type A (CO₃ substituting for OH). These signature IR bands are further confirmed by the ab initio simulations.