Browsing by Author "Page, SJ"

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    Crystal chemistry of vanadium-bearing ellestadite waste forms
    (American Chemical Society, 2018-07-16) Fang, Y; Page, SJ; Rees, GJ; Avdeev, M; Hanna, JV; White, TJ
    Vanadate ellestadites Ca10(SiO4)x(VO4)6–2x(SO4)xCl2, serving as prototype crystalline matrices for the fixation of pentavalent toxic metals (V, Cr, As), were synthesized and characterized by powder X-ray and neutron diffraction (PXRD and PND), electron probe microanalysis (EPMA), Fourier transform infrared spectroscopy (FTIR), and solid-state nuclear magnetic resonance (SS-NMR). The ellestadites 0.19 < x < 3 adopt the P63/m structure, while the vanadate endmember Ca10(VO4)6Cl2 is triclinic with space group P1̅. A miscibility gap exists for 0.77 < x < 2.44. The deficiency of Cl in the structure leads to short-range disorder in the tunnel. Toxicity characteristic leaching testing (TCLP) showed the incorporation of vanadium increases ellestadite solubility, and defined a waste loading limit that should not exceed 25 atom % V to ensure small release levels. © 2018 American Chemical Society