title: Synthesis and characterization of the crystal structure and magnetic properties of the new fluorophosphate LiNaCo[PO4]F.
abstract: The new compound LiNaCo[PO(4)]F was synthesized by a solid state reaction route, and its crystal structure was determined by single-crystal X-ray diffraction measurements. The magnetic properties of LiNaCo[PO(4)]F were characterized by magnetic susceptibility, specific heat, and neutron powder diffraction measurements and also by density functional calculations. LiNaCo[PO(4)]F crystallizes with orthorhombic symmetry, space group Pnma, with a = 10.9334(6), b = 6.2934(11), c = 11.3556(10) Å, and Z = 8. The structure consists of edge-sharing CoO(4)F(2) octahedra forming CoFO(3) chains running along the b axis. These chains are interlinked by PO(4) tetrahedra forming a three-dimensional framework with the tunnels and the cavities filled by the well-ordered sodium and lithium atoms, respectively. The magnetic susceptibility follows the Curie-Weiss behavior above 60 K with θ = -21 K. The specific heat and magnetization measurements show that LiNaCo[PO(4)]F undergoes a three-dimensional magnetic ordering at T(mag) = 10.2(5) K. The neutron powder diffraction measurements at 3 K show that the spins in each CoFO(3) chain along the b-direction are ferromagnetically coupled, while these FM chains are antiferromagnetically coupled along the a-direction but have a noncollinear arrangement along the c-direction. The noncollinear spin arrangement implies the presence of spin conflict along the c-direction. The observed magnetic structures are well explained by the spin exchange constants determined from density functional calculations.
authors.affiliation: Research Institute for Ubiquitous Energy Devices, National Institute of Advanced Industrial Science and Technology, Midorigaoka 1-8-31, Ikeda, Osaka 563-8577, Japan. benyahia.hamdi@aist.go.jp
authors.forename: Hamdi
authors.initials: H
authors.lastname: Ben Yahia
authors.forename: Masahiro
authors.initials: M
authors.lastname: Shikano
authors.forename: Shinji
authors.initials: S
authors.lastname: Koike
authors.forename: Kuniaki
authors.initials: K
authors.lastname: Tatsumi
authors.forename: Hironori
authors.initials: H
authors.lastname: Kobayashi
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Kawaji
authors.forename: Maxim
authors.initials: M
authors.lastname: Avdeev
authors.forename: Wojciech
authors.initials: W
authors.lastname: Miiller
authors.forename: Chris D
authors.initials: CD
authors.lastname: Ling
authors.forename: Jia
authors.initials: J
authors.lastname: Liu
authors.forename: Myung-Hwan
authors.initials: MH
authors.lastname: Whangbo