Effects of preparation parameters on oxygen stoichiometry in Bi4V2O11−δ

Abstract

The effects of various preparation parameters on vanadium reduction in Bi 4V 2 O 11−d have been investigated using EPR, 51V MAS solid state NMR and UV diffuse-reflectance spectroscopies and also SQUID magnetometry and powder neutron diffraction. The results confirm that a greater amount of vanadium reduction is observed in rapidly quenched samples and that significant oxidation occurs when samples are slow cooled. Evidence for spin-spin dipolar coupling is seen in the EPR patterns while uncoupled V4+ spins contribute to weak paramagnetic behaviour. Band gaps of around 2 eV from the UV data suggest there may be a significant electronic component to low temperature conductivities. The 51V NMR data are not inconsistent with the presence of mainly distorted octahedral and tetrahedral coordinations for vanadium.The relationship of the three major polymorphs in Bi 4 V 2 O 11

On structure and methylene blue degradation activity of an Aurivillius-type photocatalyst of Bi4V2O11 nanoparticles

“…More recently, Chen et al [32] reported Bi 4 V 2 O 11 hollow microspheres with hierarchical superstructures. It has been reported that the optical behavior of Bi 4 V 2 O 11 is highly sensitive to the synthetic conditions [31,33]. The synthesis method, the morphology and the size of crystals play a crucial role in determining the photocatalytic performance [32].…”

A new anion conductive bismuth–vanadium oxyfluoride

“…This does not come as a surprise, since V(IV) was also observed in Bi 2 VO 5.5 synthesized in evacuated containers. 13 From the results of microprobe analysis and EPR we can give the formula Bi 2 V V 0.7 V IV 0.3 O 5 F 0.7 (with the precision shown above), the oxygen content is only derived from the electrical neutrality assumption.…”

Structural and optical properties of melt quenched barium doped bismuth vanadate

“…The stabilization of γ-phase not only depends upon the chemical nature of dopants but also on the processing conditions [7]. Buyanova et al [8] synthesized the bismuth vanadate solid solutions with the doping of divalent metal cations such as Zn, Pb, Cu, Co and Ni by solid state reaction method.…”

“…All the three polymorphs are temperature dependent and reversible. The transitions from α2β and β2γ take place at about 400 and 600 1C, respectively [3][4][5][6][7][8]. Out of all three phases, the high temperature γ-phase is highly disordered having an inherent oxygen deficiency with higher ionic conductivity [9].…”