Synthesis, crystal structure and thermal decomposition of potassium-doped carbonated hydroxyapatite
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Tatjana I. Ivanova
Abstract
The well-crystallised polycrystalline sample of the potassium-doped waterless apatite Ca8.40K0.34 · [(PO4)3.15(HPO4)1.30(CO3)]1.55(OH)2 (a = 9.4015(3), c = 6.8985(2) Å, sp.gr. P63/m, Z = 1) with very high carbonate content (7.7 wt% of CO2) has been prepared by the reaction of calcite with KH2PO4 solution under hydrothermal conditions. The Rietveld refinement (Rwp = 0.052) of its crystal structure allowed to find the new orientation of a carbonate triangle. It crosses a PO4 tetrahedron just in its centre so that the positions of a carbon atom coincides with that of a phosphorous atom, and the triangle plane is parallel to the z-axis. The charge disbalance is compensated mainly by the vacancies in the cation sites. The absence of lattice water in the channels is the consequence of the extremely high concentrations of the divalent anions replacing PO4 tetrahedra in the structure.
© 2004 Oldenbourg Wissenschaftsverlag GmbH
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Artikel in diesem Heft
- Shadowing and absorption corrections of single-crystal high-pressure data
- Orthotetrahedral crystal structures My(TO4)z (T = Si, Ge, P, As, S, Se, Cl, Br, I): geometrical-topological analysis, quasi-binary representation, and comparison with the AyXz compounds by the method of coordination sequences
- Synthesis, crystal structure and thermal decomposition of potassium-doped carbonated hydroxyapatite
- Solid state miscibility in the pseudo-binary TiO2—(FeSb)O4 system at 1373 K
- Multiple twinning of diamond synthesized by acetylene flame
- Variable temperature (100–360 K) single-crystal X-ray diffraction study of the orthorhombic polymorph of paracetamol (p-hydroxyacetanilide)
- Crystal and molecular structures of two triorganophosphinegold(I) 2-amino-cyclopent-1-ene-1-carbodithioates
