Synthesis and Characterization of the Crystal Structure and Magnetic Properties of the New Fluorophosphate LiNaCo[PO4]F

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• 作者：Hamdi Ben Yahia ; Masahiro Shikano ; Shinji Koike ; Kuniaki Tatsumi ; Hironori Kobayashi ; Hitoshi Kawaji ; Maxim Avdeev ; Wojciech Miiller ; Chris D. Ling ; Jia Liu ; Myung-Hwan Whangbo
• 刊名：Inorganic Chemistry
• 出版年：2012
• 出版时间：August 20, 2012
• 年：2012
• 卷：51
• 期：16
• 页码：8729-8738
• 全文大小：588K
• 年卷期：v.51,no.16(August 20, 2012)
• ISSN：1520-510X

文摘

The new compound LiNaCo[PO₄]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[PO₄]F were characterized by magnetic susceptibility, specific heat, and neutron powder diffraction measurements and also by density functional calculations. LiNaCo[PO₄]F crystallizes with orthorhombic symmetry, space group Pnma, with a = 10.9334(6), b = 6.2934(11), c = 11.3556(10) 脜, and Z = 8. The structure consists of edge-sharing CoO₄F₂ octahedra forming CoFO₃ chains running along the b axis. These chains are interlinked by PO₄ 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鈥揥eiss behavior above 60 K with 胃 = 鈭?1 K. The specific heat and magnetization measurements show that LiNaCo[PO₄]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 CoFO₃ 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.