Effects of Iron Doping on the Physical Properties of Quaternary Ferromagnetic Sulfide: Ba 2 Fe 0.6 V 1.4 S 6 .

The mixed-metal sulfide compound with the formula Ba2 Fe0.6 V1.4 S6 was successfully synthesized via solid-state reaction. Ba2 Fe0.6 V1.4 S6 has a quasi-one-dimensional structure and crystallizes in the hexagonal space group P63 /mmc. The structure is composed of face-sharing anion octahedron [MS6 ]8- (M = V or Fe) units to construct infinite chains along the c axis, in which the Fe atoms randomly occupy the V sites. The Ba2+ ions reside between adjacent chains. Magnetic susceptibility measurements reveal a transition between paramagnetism and ferromagnetism around 25 K. The small polaron hopping (SPH) conduction behavior has been observed in the higher temperature region (75-300 K), while in the lower temperature region (25-74 K), the resistivity features a variable range hopping mechanism (VRH). The analysis of density of states indicates that Fe-3dz2 and S-3p states mainly dominate the valence band maximum, while Fe-3dz2 states contribute significantly to the magnetic susceptibility.