Synthesis and Magnetic Properties of the Ternary Oxofluoride Fe3Sb4O6F6

• The new compound Fe(3)Sb(4)O(6)F(6)was prepared by hydrothermal synthesis and its crystal structure was determined from single-crystal X-ray diffraction data. The synthesis was made under slightly basic conditions to prevent oxidation of Fe(2+)to Fe3+. The compound crystallizes in the cubic space groupI-43mwith separate crystallographic sites for Fe(2+)and Sb3+. Fe(3)Sb(4)O(6)F(6)is isostructural with M3Sb4O6F6(M = Co, Ni, Zn). The crystal structure is comprising distorted [FeO2F4] octahedra connected via corner sharing at F-atoms and [SbO3] trigonal pyramids that form [Sb4O6] units that connect via O-atoms to the Fe-atoms. Mossbauer spectroscopy measurements on the hydrothermal synthesis products prove the majority phase contains Fe in the oxidation state +2. Powder X-ray diffraction suggests that an additional phase of the Mossbauer sample containing Fe(3+)can be attributed to FeSbO(2)F(2)as secondary phase. Fe(3)Sb(4)O(6)F(6)exhibits antiferromagnetic order below ca. 72 K succeeded by a second magnetic phase transition at ca. 30 K. Strong antiferromagnetic spin-exchange interaction is attributed to 180 degrees Fe-F-Fe superexchange pathways identified in the crystal structure.

Ämnesord

NATURVETENSKAP  -- Kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences (hsv//eng)

Nyckelord

Hydrothermal techniques

Oxyfluorides

Structure elucidation

Magnetic properties

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