Browsing by Subject "Rietveld refinements"

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Arsenate substitution in lead hydroxyl apatites: Rietveld refinements and Raman spectroscopic study
(Data obrony: 2014-09-24) Giera, Alicja
Wydział Geologii, Geofizyki i Ochrony Środowiska
This paper focuses on hydroxyl analogues of pyromorphite-mimetite solid solutions, the phases belonging to the apatite supergroup. The aim of the study was their detailed structural analysis and examination of spectroscopic features in regard to the arsenate substitution in lead hydroxyl apatites. Seven synthetic powders were analyzed with the use of synchrotron-based X-ray diffraction, Raman spectroscopy and scanning electron microscopy (SEM-EDS). The structure Rietveld refinements revealed systematic changes of the unit-cell parameters with the isomorphic substitution of phosphates by arsenates. The lowering of hexagonal crystal symmetry to the symmetry of monoclinic crystal system was detected in phases from the OH-analogues of pyromorphite-mimetite series for the first time. The position and intensity of bands on Raman spectra as well as their assignment to the vibrational modes were determined. The linear correlation of the positions of selected bands with the arsenic content was established.