Structural, Magnetic, and Optical Properties of A3V4(PO4)6 (A = Mg, Mn, Fe, Co, Ni)

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• 作者：Spencer H. Porter ; Jie Xiong ; Maxim Avdeev ; David Merz ; Patrick M. Woodward ; Zhenguo Huang
• 刊名：Inorganic Chemistry
• 出版年：2016
• 出版时间：June 20, 2016
• 年：2016
• 卷：55
• 期：12
• 页码：5772-5779
• 全文大小：413K
• 年卷期：0
• ISSN：1520-510X

文摘

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 μ_B 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⁺.