Formation of Fluorapatite in the Equilibrium System CaO–P2O5–HF–H2O at 298 K in a Nitrogen Atmosphere

The process of biomineralization apatite in nature has been studied by scientists from various fields science for more than a century. Unlike the volcanogenic, hydrothermal, and other types igneous apatites, genesis which is entirely clear, formation phosphate ores marine sedimentary origin still debatable. Since concentrations water bodies are too low spontaneous precipitation solid phosphates, study different ways their concentration particular interest. In this work, phase equilibria system CaO–P2O5–HF–H2O at 298 K, involving fluorapatite formation, have studied. Fluorapatite known to be most common mineral main source phosphorus on Earth, playing an important role mineralization dental tissues vertebrates. equilibrium defined above was mass fraction liquid components, i.e., conditions close natural. It shown that compounds variable composition with structure containing HPO42− ions were formed acid region system. These pH ≤ 7.0 invariant points monetite, CaHPO4, fluorite, CaF2. Stoichiometric lowest components neutral weakly alkaline medium had point Ca(OH)2. resulting phases found dependent Ca/P ratio initial phase. Fluorite CaF2 present each sample obtained study.