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      https://www.ias.ac.in/article/fulltext/jess/127/08/0110

    • Keywords

       

      Uranium; photoluminescence; X-ray absorption spectroscopy; X-ray diffraction.

    • Abstract

       

      The structural and spectroscopic characteristics of phosphatic ferruginous shale samples from the Bijawar Group rocks from Sagar District of Madhya Pradesh (India) have been probed for identification of uranium species. Fluorapatite (Ca$_{5}$(PO$_{4}$)$_{3}$F, FAP) and haematite ($\alpha$-Fe$_{2}$O$_{3}$) were identified as the main phases in the separated mineral concentrates. The photoluminescence (PL) and X-ray absorption near edge spectroscopy (XANES) studies pointed to a strong experimental evidence of both U(IV) and U(VI) oxidation states in the mineral concentrate portion obtained from the same parent host rock. The PL spectrum has confirmed the charge transfer (f–d) transition bands in UV and near-UV regions with emission peaks at ca. 290, 313, 336, 399 and 416 nm, which has been attributed to the substitution of Ca$^{2+}$ ions by U(IV) in FAP and broad structureless emission due to stabilisation of U(VI) as UO$_6^{6-}$ in haematite. Time-resolved spectroscopy studies have revealed biexponential decay components lasting 2–5 ns for U(IV) species and 10 $\mu$s for U(VI) species. These characterisations revealed the fundamental information about the oxidation state and form of uranium in this region. Remediation measures for the Bijawar region are also suggested.

    • Author Affiliations

       

      Pragya Pandit1 Shailendra Kumar1 Pargin Bangotra2 Rohit Mehra2 Manoj Mohapatra3 Madhuparna Roy1 Singh A K4

      1. Atomic Minerals Directorate for Exploration and Research, New Delhi 110 066, India.
      2. Dr. B.R. Ambedkar National Institute of Technology, Jalandhar 144 011, India.
      3. Radiochemistry Division, Bhabha Atomic Research Center, Mumbai 400 085, India.
      4. Maharaja Surajmal Institute of Technology, USICT, GGSIPU, New Delhi 110 058, India.
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  • Journal of Earth System Science | News

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