title: Structural, Magnetic, and Optical Properties of A3V4(PO4)6 (A = Mg, Mn, Fe, Co, Ni).
abstract: 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 A(2+) ion. Cation disorder on the octahedral sites increases as the ionic radii of A(2+) ion decreases. Direct-current magnetic susceptibility measurements indicate that all compounds with magnetic A(2+) 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 V(3+) ions. The striking emerald green color of Co3V4(PO4)6 arises from the combined effects of d-d transitions involving both V(3+) and Co(2+).
authors.affiliation: Institute for Superconducting and Electronic Materials, University of Wollongong , Wollongong, NSW 2522, Australia.
authors.forename: Spencer H
authors.initials: SH
authors.lastname: Porter
authors.affiliation: Department of Chemistry & Biochemistry, The Ohio State University , 100 W. 18th Avenue, Columbus, Ohio 43210, United States.
authors.forename: Jie
authors.initials: J
authors.lastname: Xiong
authors.affiliation: Bragg Institute, Australian Nuclear Science and Technology Organization , Menai, NSW 2234, Australia.
authors.forename: Maxim
authors.initials: M
authors.lastname: Avdeev
authors.affiliation: Institute for Superconducting and Electronic Materials, University of Wollongong , Wollongong, NSW 2522, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Merz
authors.affiliation: Department of Chemistry & Biochemistry, The Ohio State University , 100 W. 18th Avenue, Columbus, Ohio 43210, United States.
authors.forename: Patrick M
authors.initials: PM
authors.lastname: Woodward
authors.affiliation: Institute for Superconducting and Electronic Materials, University of Wollongong , Wollongong, NSW 2522, Australia.
authors.forename: Zhenguo
authors.initials: Z
authors.lastname: Huang