A new anion conductive bismuth–vanadium oxyfluoride

Abstract

A new anion conductive oxyfluoride Bi 2 VO 5 F 0.7 has been obtained. Its crystal structure, related to the wellknown Aurivillius phases, has been determined from powder X-ray and neutron diffraction data combined with a piezo test and magnetic measurements (I4mm, a~3.869(3) Å , c~15.648(6) Å , R p~4 .41, R wp~9 .50%). The transport properties of this compound have been studied as a function of temperature by impedance spectroscopy. The relation of the Bi 2 VO 5 F 0.7 crystal structure and anion conductivity with different modifications of Bi 2 VO 5.5 oxide is discussed.

Synthesis and Characterization of the Aurivillius Phase CoBi2O2F4

“…There are three previously reported oxo-fluoride Aurivillius phases: NbBi 2 O 5 F, TiBi 2 O 4 F 2 , and VBi 2 O 5 F . In these phases, the octahedrally coordinated cation has an oxidation state of 4+ or 5+.…”

“…Most Aurivillius phases are oxides and their crystal structure consists of alternating [Bi 2 O 2 ] 2+ layers and n perovskite layers ( n ≤ 5), as found, for example, for Bi 2 MoO 6 and Bi 4 Ti 3 O 12 with n = 1 and 2, respectively. , In the present study, a new oxofluoride, CoBi 2 O 2 F 4 , belonging to the Aurivillius family of compounds, has been synthesized and characterized. So far, there are only three such oxofluorides described in the literature: TiBi 2 O 4 F 2 , NbBi 2 O 5 F, and VBi 2 O 5 F. , CoBi 2 O 2 F 4 , to the best of our knowledge, is the first compound in the Co 2+ –Bi 3+ –O–F system constituting the first oxo-fluoride Aurivillius phase with Co 2+ . The crystal structure determination is based on single-crystal X-ray diffraction (XRD) data.…”

Synthetic strategies for new vanadium oxyfluorides containing novel building blocks: structures of V(iv) and V(v) containing Sr4V3O5F13, Pb7V4O8F18, Pb2VO2F5, and Pb2VOF6

“…The 0-D structures include isolated VO x F y polyhedra, dimeric and tetrameric BBs, whereas the 1-D structures include linear, zigzag, ladder-like, or even more complex chains. 2-D structures, although very rare, occur in VOF 3 19 or Bi 2 VO 5 F. 20 where, however, the SbF 6 polyhedra are corner-sharing through exclusively F atoms. 70 A unique 1-D feature is found in 2, consisting of V atoms linked together via alternating O and F atoms in a -V-O-V-F-Vfashion, creating zigzag type chains.…”

S = 1/2 Chain in BiVO3F: Spin Dimers versus Photoanodic Properties

“…Such oxyfluoride chains have provided excellent models for low-dimensional magnetism, due to the minimization of electronic delocalization through electronegative F − bridges. 9 To date, the concerned Bi−V−O−F chemical system is almost empty, since only 3D F − -doped BiVO 4 10 and Bi 2 VO 5 F 11 have been reported so far. In the former, the F − doping enables enhanced photoelectrochemical performances, while the latter corresponds to F − doping in the perovskite slabs of the well-known 2D Bi 4 V 2 O 11 , the best high-temperature ionic conductor ever, and, thus, induces a minor amount of V 4+ .…”