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Browsing by Subject "substitutions"

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    Item type:Thesis, Access status: Restricted ,
    Wpływ obecności jonów węglanowych na powstawanie, strukturę i właściwości hydroksylmimetytu $Pb_{5}(AsO_{4})_{3}OH$
    (Data obrony: 2012-07-16) Lempart, Małgorzata
    Wydział Geologii, Geofizyki i Ochrony Środowiska
    Hydroxylmimetite $Pb_{5}(AsO_{4})_{3}OH$ is a mineral isostructural with hydroxylapatite $Ca_{5}(PO_{4})_{3}OH$. Carbonate $CO_{3}{^{2-}}$ substitutions, well known from hydroxylapatites, have never been studied in hydroksylmimetite. Carbonated hydroxylmimetite was synthesized from aqueous solutions in the presence of $NH_{4}HCO_{3}$. The solids were characterized using X-ray powder diffraction (XRD), wet chemical analysis, CHNS analysis, scanning electron microscopy (SEM/EDS), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy and thermal analysis (TG/DTA) with EGA - evolved gas analysis. The results suggest that, similarly to hydroxylapatite, carbonate ion can be incorporated into hydroxylmimetite structure as type B substitution (substitution for arsenate tetrahedron as type A substitution (for hydroxyl group in apatite channel position). The presence of atmospheric $CO_{2}$ in contact with aqueous solution is sufficient to provide a source of substituting carbonate in hydroxylmimetite precipitating from the solution.