Molten salt synthesis and structural characterization of novel salt-inclusion vanadium bronze Cs_5FeV_5O _(13)Cl_6

摘要

Single crystals of a new reduced vanadate phase, Cs_5FeV _5O_(13)Cl_6, have been grown from the reaction of metal oxides V_2O_5 and Fe_2O_3 in the presence of a metal reducing agent in a eutectic CsCl/NaCl flux. This compound adopts a tetragonal structure (P4mm, a = 10.943(3) ?, c = 10.535(4) ?, Z = 2) that consists of reduced vanadate layers separated by ionic layers comprised of [FeCl_6]~(3-) anions and Cs~+ cations. There are two distinct vanadium sites in the structure of this compound; V~(4+) is in square pyramidal configuration, and V ~(5+) has a tetrahedral coordination environment. The ~(51)V NMR Knight shift and the magnetic susceptibility data indicate the delocalization of the unpaired electron of vanadium. Ferrimagnetic ordering is observed at 5 K.