Molten Salt Synthesis and Structural Characterization of Novel Salt-Inclusion Vanadium Bronze Cs5FeV5O13Cl6

Single crystals of a new reduced vanadate phase, Cs5FeV5O13Cl6, have been grown from the reaction of metal oxides V2O5 and Fe2O3 in the presence of a metal reducing agent in e eutectic CsCl/NaCl flux. This compound adopts a tetragonal structure (P4/nmm, a = 10.943(3) angstrom, c = 10.535(4) angstrom, Z = 2) that consists of reduced vanadate layers separated by ionic layers comprised of [FeCl6](3-) anions and Cs+ cations. There are two distinct vanadium sites in the structure of this compound; V4+ is in square pyramidal configuration, and V5+ has a tetrahedral coordination environment. The V-51 NMR Knight shift and the magnetic susceptibility data indicate the delocalization of the unpaired electron of vanadium. Ferrimagnetic ordering is observed at 5 K.