Structural and spectroscopic study of arsenate and vanadate incorporation into apatite group: Implications for semi-quantitative estimation of As and V contents in apatite.

The solid solutions of mimetite-vanadinite series were synthesized at room temperature through aqueous precipitation method and were characterized with Scanning Electron Microscope-Energy Dispersive Spectrometer (SEM-EDS), X-ray diffraction (XRD), infrared and Raman spectroscopy. Based on the XRD analyses, it showed that all the samples crystallize with the same structure. A and c parameters vary smoothly with substitution of AsO4 3- for VO4 3- . In the FT-IR spectra of mimetite-vanadinite solid solutions series, the bands corresponding to stretching (v3 ) vibrations of AsO4 3- and VO4 3- ions were observed in the range 700-900cm-1 , and the bending (v4 ) vibrations of OAsO and OVO were observed in the range 310-400cm-1 . In the Raman spectra, the bands attributed to vibrations in the VO4 3- appeared at 830-700cm-1 , 420-290cm-1 . The bands attributed to vibrations in the AsO4 3- appeared in the ranges 740-820cm-1 , 410-310cm-1 . In addition, the peak positions of the dominant antisymmetric stretching (v3 ) of VO bond around 706cm-1 of IR spectra for the prepared solids also varies with the different As/(As+V) ratio, and the relationship is linear, which can be an implication for semi-quantitative estimation of As and V contents in lead apatites.