Tarasenko S. Synthesis in saline melts and properties of apatites of the composition (M,M')10(PO4)6X2, (M - Ca, Sr, Ba, Eu, Pb; M' - Eu, Cu; X - OH, F)

The dissertation is devoted to the development of synthesis of calcium fluor- and hydroxyapatites (CaFap and CaHap), strontium and europium-substituted strontium, barium and lead fluorapatites, and to the study of their physical-chemical properties and possible application. The mechanism of synthesis of apatites in the melt NaCl-KCl of equimolar composition is studied, as well as a new way of their synthesis in the melt Li2CO3-Na2CO3-K2CO3 of eutectic composition is developed. The general mechanism of synthesis consists of dissolution of components in saline melt, their interaction in the soluble state and sedimentation of products. The thermodynamic estimation of solubility in the melts is carried out and general regularities of its changes at cationic and anionic substitutions are established. It is shown that solubility decreases at the transfer from the carbonate melt to chloride one. Solubility should increase in the series of Ca-Sr-Ba-Pb compounds, as well as decrease in the series of fluoride-carbonate-hydroxide-oxide of metal. The experimental results completely confirm calculation data. It has been shown by X-ray phase analysis that lattice parameters of synthesised calcium apatites increase in comparison with standard due to substitution for F- on OH-, CO32- or for OH- on CO32-, Cl-. IR spectroscopy completely confirmed the fact of substitution. X-ray phase analysis, diffuse reflection spectroscopy and luminescent analysis showed an exchange reactions of Eu2+ ions in chloride melt with calcium, strontium and barium fluorapatites and fluorides of metals. General regularities and mechanism of sorption of Pb2+ and Cu2+ ions from aqueous solutions by CaFap and CaHap were established. Keywords: synthesis, fluorapatite, hydroxyapatite, structure, saline melt, batch components, dissolution, exchange reactions, sorption.