Browsing by Author "Merz, D"

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    Structural, magnetic, and optical properties of A3V4(PO4)6 (A = Mg, Mn, Fe, Co, Ni)
    (American Chemical Society, 2016-05-26) Porter, SH; Xiong, J; Avdeev, M; Merz, D; Woodward, PM; Huang, Z
    Combined synchrotron and neutron powder diffraction indicates that A3V4(PO4)6 (A = Mg, Mn, Fe, Co, Ni) compounds crystallize with triclinic P1̅ symmetry. Lattice parameters expand as expected with successive increases in the ionic radius of the A2+ ion. Cation disorder on the octahedral sites increases as the ionic radii of A2+ ion decreases. Direct-current magnetic susceptibility measurements indicate that all compounds with magnetic A2+ ions order anti-ferromagnetically with transition temperatures ranging from 12 to 15 K. Effective magnetic moments for A3V4(PO4)6 (A = Mg, Mn, Fe, Co, Ni) are 5.16, 11.04, 10.08, 9.76, and 7.96 μB per formula unit, respectively, in line with calculated values for high-spin transition metal ions. With the exception of Co3V4(PO4)6 the ultraviolet–visible spectra are dominated by d–d transitions of the V3+ ions. The striking emerald green color of Co3V4(PO4)6 arises from the combined effects of d–d transitions involving both V3+ and Co2+. © 2016 American Chemical Society